What's more, lauric acid is actually right on the border between medium- and long-chain fatty acids: Its chemical backbone is 12 carbons long, and medium-chain fatty acids range from 6 to 12 carbons long.
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And it might be the best hope also for climate change and sequestration of carbons.
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As the bacteria munch on organic carbons like glucose, they churn out CO2 as a waste byproduct.
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"Medium-chain triglycerides refers to saturated fatty acids that are six-to-12 carbons in length," he says.
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Orion, the engineered carbons firm, also fell about 3.7 percent after announcing a secondary common stock offering on Wednesday.
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The planet is full of complex carbons of its own—ones like vinyl cyanide that could potentially form "membrane-like" stuctures.
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"The vapor contains elevated levels of nicotine, particulate matter, glycerin propylene glycol, formaldehyde, polycyclic aromatic carbons and heavy metals," Tan said.
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Lenovo claims the problem was first noticed when three different users reported that the batteries in their Thinkpad X1 Carbons were overheating.
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This particular one, 11-cis-retinal, is a chain of carbons with a dogleg bend at one double-bond along its backbone.
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Different sites may use different minerals or carbons sourced from their environments: Hydrogen may come from friction, or radiolysis, instead of serpentinization.
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A little molecule like butane—four carbons long—is good for a cigarette lighter; a ship's engine may use something 10 times longer.
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A new experiment instead swapped some of the carbons for silicon atoms, creating silicon-vacancy diamonds that could make for potentially useful quantum systems.
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"There's relay failure, the pins wear out, the housing, the contacts wear out, the carbons wear out, the car switch — same thing," he said.
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The bacteria converts carbon-based organic waste into organic acids, according to chief executive Luna Yu. The two-step process is based on two groups of specialized bacteria used throughout the process: The first group digests food waste, producing short-chain carbons as volatile fatty acids, acting as the precursor feed stock for the second group, which eats these carbons and converts them into bioplastics.
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But if you swap one of the carbons with a nitrogen, you're left with vacant center where there should be, but is not, a carbon atom.
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He said France would also review its public export guarantees in line with Paris' commitment to stop financing projects that increase the growth of carbons emissions.
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Whereas the older chemicals had longer chains of fluorinated carbons, these newer ones have shorter chains, which the chemical companies claim makes them safer for health and the environment.
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Vattenfall, which produces energy from carbons, nuclear, hydropower and wind, said higher prices for coal, gas and CO2 emission allowances had squeezed margins in its power plants that use those fuels.
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The plant would deploy new technology to superheat coal, would remove most of its carbons and other harmful pollutants and was to be a showcase for local ingenuity and engineering savvy.
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Some of it is aliphatic carbons that leak from stars, and a new study from University of New South Wales (UNSW) and Ege University researchers has found there is an awful lot of it.
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"The chlorine grabs the electrons from the hydrocarbons, the oxygens and chlorides get bonded to the carbons, and this makes your food stains water soluble, but just enough to unstick them from the dishware," Dr. Nyman said.
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More specifically, Cabot's results were impacted by a downdraft in spot carbon black pricing in China, weak demand (including plastics industry channel destocking) and diminished margins in its Specialty Carbons business, and owing to some adverse feedstock differentials during the quarter.
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Specifically, they've been interested in how the carbons bond together—whether each carbon bonds to its neighbor with two electrons, or whether each bonds with a single electron to one neighbor and three electrons to its other neighbor in an alternating fashion.
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Distillation and cracking also produce plenty of small molecules containing just two or three carbons; these form the basis for the petrochemical industry, which uses them either for their own properties or as the building blocks for all manner of plastics, fibres and pharmaceuticals.
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According to Bloomberg, Fink told the New Jersey Pension Investment Council on Wednesday that "carbons are going to be cheaper for longer", echoing sentiment expressed last week in which he suggests that the crude price, despite the recent rebound, was still yet to hit its cyclical bottom.
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Physical properties of the two classes of carbons are quite different. Graphitizing carbons are soft and non-porous, while non-graphitizing carbons are hard, low density materials. Non-graphitizing carbons are otherwise known as chars, hard carbons or, more colloquially, charcoal. Glassy carbon is also an example of non-graphitizing carbon.
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For example, if the Cβ of leucine appears as a positive peak (2 aliphatic carbons attached), then the Cγ (3 aliphatic carbons attached) and Cα (1 aliphatic carbons attached) would appear negative.
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Two low-energy waste products, H2O and CO2, are created during this cycle. The citric acid cycle is an 8-step process involving 18 different enzymes and co-enzymes. During the cycle, acetyl-CoA (2 carbons) + oxaloacetate (4 carbons) yields citrate (6 carbons), which is rearranged to a more reactive form called isocitrate (6 carbons). Isocitrate is modified to become α-ketoglutarate (5 carbons), succinyl-CoA, succinate, fumarate, malate, and, finally, oxaloacetate.
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However, reducing the SAM from 6 carbons to 2 carbons decreases signal, and peak current is generated using a 6-carbon SAM.
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Both isoprenoid chains, geranylgeranyl pyrophosphate (GGpp) and farnesyl pyrophosphate are products of the HMG-CoA reductase pathway. The product of HMG CoA reductase is mevalonate. By combining precursors with 5 carbons, the pathway subsequently produces geranyl pyrophosphate (10 carbons), farnesyl pyrophosphate (15 carbons) and geranylgeranyl pyrophosphate (20 carbons). Two farnesyl pyrophosphate groups can also be combined to form squalene, the precursor for cholesterol.
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That part of the four-member ring, exclusive of the shared edge, has 2 carbons. The edge itself, exclusive of the two vertices that define it, has 0 carbons.
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Similar structures have been discovered in the brown alga Laminaria sinclairii, with 18 or 20 carbons and 4, 5 or 6 double bonds, and in the red alga Polyneura latissima, with 20 carbons and 5 double bonds.
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The accumulation of G6P will shunt carbons into the pentose phosphate pathway.
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Steroid nomenclature: Pregnanes have carbons 1 through 21. Pregnanes are steroid derivatives with carbons present at positions 1 through 21. Most biologically significant pregnane derivatives fall into one of two groups: pregnenes and pregnadienes. Another class is pregnatrienes.
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The alkene carbon-carbon double bond is made from two sp trigonally hybridized carbons.
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The potency of the NNRTIs changed when the triazine nitrogen atoms were substituted with carbons.
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Naphthenic acids (NAs) are a mixture of several cyclopentyl and cyclohexyl carboxylic acids with molecular weight of 120 to well over 700 atomic mass units. The main fraction are carboxylic acids with a carbon backbone of 9 to 20 carbons. McKee et al. claim that "naphthenic acids (NAs) are primarily cycloaliphatic carboxylic acids with 10 to 16 carbons"[1], although acids containing up to 50 carbons have been identified in heavy petroleum.
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Aucubin is a monoterpenoid based compound. Aucubin, like all iridoids, has a cyclopentan-[C]-pyran skeleton. Iridoids can consist of ten, nine, or rarely eight carbons in which C11 is more frequently missing than C10. Aucubin has 10 carbons with the C11 carbon missing.
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The shared carbons are labeled 4a (between 4 and 5) and 8a (between 8 and 1).
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Estrogen esters also occur naturally in the body, for instance estrogen conjugates like estrone sulfate and estrone glucuronide and the very long-lived lipoidal estradiol, which is constituted by ultra-long-chain esters like estradiol palmitate (ester of 16 carbons) and estradiol stearate (ester of 18 carbons).
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The remaining 75% have a trans 5:10 ring junction. The clerodane skeleton contains 20 carbons and a decalin core. There are four additional distinctions that refer to the stereochemistry of the decalin ring junction and the substituents on the C-8 and C-9 carbons.
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Phytane also has many stereoisomers because of its three stereo carbons, C-6, C-10 and C-14. Whereas pristane has two stereo carbons, C-6 and C-10. Direct measurement of these isomers has not been reported using gas chromatography. alt= Chemical structure of α-tocopherol.
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Although two transition states occur during a SN1 reaction (dissociation of the leaving group and then attack by the nucleophile), the dissociation of the leaving group is almost always the rate-determining step. Hence, the activation energy and therefore rate of the reaction will depend only upon the dissociation step. First, consider the reaction at secondary and tertiary carbons. As the BEP principle notes, experimentally SN1 reactions at tertiary carbons are faster than at secondary carbons.
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Although two transition states occur during a SN1 reaction (dissociation of the leaving group and then attack by the nucleophile), the dissociation of the leaving group is almost always the rate-determining step. Hence, the activation energy and therefore rate of the reaction will depend only upon the dissociation step. First, consider the reaction at secondary and tertiary carbons. As the BEP principle notes, experimentally SN1 reactions at tertiary carbons are faster than at secondary carbons.
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Long-chain fatty alcohol oxidases vary between species in their specificity; some species have multiple different alcohol oxidases. They generally have a broad range of substrates, ranging from short chain alcohols starting at 4 carbons to the longest long-chain alcohols at 22 carbons. Some can also oxidize select diols, secondary alcohols, hydroxy fatty acids, and even long-chain aldehydes. However, each enzyme is optimized to function for specific alcohol, often between 10 and 16 carbons.
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Ribose and deoxyribose (in RNA and DNA respectively) are pentose sugars. Examples of heptoses include the ketoses, mannoheptulose and sedoheptulose. Monosaccharides with eight or more carbons are rarely observed as they are quite unstable. In aqueous solutions monosaccharides exist as rings if they have more than four carbons.
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The oxygen atoms attached to carbons in positions that do not correspond to polyketides—carbons 8 and 13 (the ether bridge), carbon 2 (the methoxy substituent), and carbon 18 (on the hydroxyethyl chain attached to the lactone ring) are derived from molecular oxygen. Last steps of the biosynthesis of Nargenicin.
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These can be described by the condensed structural formulas –– and ––. The third isomer of is the ether methoxyethane (ethyl-methyl-ether). Unlike the other two, it has the oxygen atom connected to two carbons, and all eight hydrogens bonded directly to carbons. It can be described by the condensed formula –O––.
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Ryoo, R., et al. “Lanthanum-catalysed synthesis of microporous 3D graphene-like carbons in a zeolite template”, Nature, 2016.
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The atomic structure of atheneite is very similar to that of the hexagonal structure carbons that make up graphite.
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Ethyne, or acetylene, has the chemical formula CH 2 CH 2, with a triple bond between the two carbons.
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The capacitance of the anode is several orders of magnitude larger than that of the cathode. As a result, the change of the anode potential during charge and discharge is much smaller than the change in the cathode potential. Other candidate anode materials are being investigated as alternative to graphitic carbons, such as hard carbon, soft carbon, graphene-based carbons. The expected benefit compared to graphitic carbons is in increasing the doped electrode potential improving power capability as well as safety in regard to metal plating.
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The physiological behavior of morphinans (naturally occurring and semi-synthetic derivatives) is thought to be associated with the aromatic A ring, the nitrogen-containing D ring and the "bridge" between these two rings formed by carbons 9, 10 and 11 of the core, with the D ring "above" the core (levorotatory). Small groups are usually found on morphinan derivatives at carbons 3 and 6. Many such derivatives have an epoxy group between carbons 4 and 5 (i.e., 4,5α-epoxy), thereby forming an E ring.
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In general, gaseous ozone treatment or solution-phase nitric acid oxidation is utilized to remove sp2 carbons and metal impurities.
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In such an off-resonance decoupled spectrum, only 1H atoms bonded to a carbon atom will split its 13C signal. The coupling constant, indicating a small frequency difference between split signal peaks, would be smaller than in an undecoupled spectrum. Looking at a compound's off-resonance proton-decoupled 13C spectrum can show how many hydrogens are bonded to the carbon atoms to further help elucidate the chemical structure. For most organic compounds, carbons bonded to 3 hydrogens (methyls) would appear as quartets (4-peak signals), carbons bonded to 2 equivalent hydrogens would appear as triplets (3-peak signals), carbons bonded to 1 hydrogen would be doublets (2-peak signals), and carbons not bonded directly to any hydrogens would be singlets (1-peak signals).
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In 1H NMR spectroscopy, the hydrogen bonded to the carbon adjacent to double bonds will give a δH of 4.5–6.5 ppm.The double bond will also deshield the hydrogen attached to the carbons adjacent to sp2 carbons, and this generates δH=1.6–2. ppm peaks. Aromatic groups will have δH=6.5–8.5 ppm peaks.
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13C NMR SpectrumLike proton NMR, carbon-13 (13C) NMR spectroscopy is a method used in molecular structure determination. 13C NMR reveals the types of carbons present in a molecule based on chemical shifts that correspond to certain functional groups. N-Acetylglutamic acid exhibits carbonyl carbons most distinctly due to the three carbonyl-containing substituents.
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Graphitizing and non-graphitizing carbons (alternatively graphitizable and non-graphitizable carbon) are the two categories of carbon produced by pyrolysis of organic materials. Rosalind Franklin first identified them in a 1951 paper in Proceedings of the Royal Society.. In this paper, she defined graphitizing carbons as those that can transform into crystalline graphite by being heated to 3000°C, while non-graphitizing carbons don't transform into graphite at any temperature. Precursors that produce graphitizing carbon include polyvinyl chloride (PVC) and petroleum coke. Polyvinylidene chloride (PVDC) and sucrose produce non-graphitizing carbon.
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The naming of polycyclic alkanes is more complex, with the base name indicating the number of carbons in the ring system, a prefix indicating the number of rings (e.g., "bicyclo"), and a numeric prefix before that indicating the number of carbons in each part of each ring, exclusive of vertices. For instance, a bicyclooctane which consists of a six-member ring and a four-member ring, which share two adjacent carbon atoms which form a shared edge, is [4.2.0]-bicyclooctane. That part of the six-member ring, exclusive of the shared edge has 4 carbons.
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The number of open chain stereoisomers for an aldose monosaccharide is larger by one than that of a ketose monosaccharide of the same length. Every ketose will have 2(n−3) stereoisomers where n > 2 is the number of carbons. Every aldose will have 2(n−2) stereoisomers where n > 2 is the number of carbons. These are also referred to as epimers which have the different arrangement of −OH and −H groups at the asymmetric or chiral carbon atoms (this does not apply to those carbons having the carbonyl functional group).
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Omega-3 fatty acids, also called ω−3 fatty acids or n−3 fatty acids, are polyunsaturated fatty acids (PUFAs). Omega−3 fatty acids are important for normal metabolism. Mammals are unable to synthesize omega−3 fatty acids, but can obtain the shorter-chain omega−3 fatty acid ALA (18 carbons and 3 double bonds) through diet and use it to form the more important long-chain omega−3 fatty acids, EPA (20 carbons and 5 double bonds) and then from EPA, the most crucial, DHA (22 carbons and 6 double bonds).
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Mr Carbon's business trips by air contribute to the fastest growing source of CO2. The combined total of the Carbons' yearly air pollution is 45 tons. Also shown are Mr and Mrs Tan, a fictional couple who live in an average Chinese suburb. At present, their energy usage is one seventh of that of the Carbons.
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As of 2003, there were 126 GAs identified from plants, fungi, and bacteria. Gibberellins are tetracyclic diterpene acids. There are two classes based on the presence of either 19 or 20 carbons. The 19-carbon gibberellins, such as gibberellic acid, have lost carbon 20 and, in place, possess a five- member lactone bridge that links carbons 4 and 10.
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The occurrence of this kind of flaw is less common in diamonds compared to pinpoint inclusions. Carbons are usually seen in white or blue-white stones. Carbons are not commonly found in diamonds of poorer colors. Within the trade, these are called "carbon spots" and may be cleavage cracks which have developed through uneven heating or a blow.
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For the Calvin cycle to continue, RuBP (ribulose 1,5-bisphosphate) must be regenerated. So, 5 out of 6 carbons from the 2 G3P molecules are used for this purpose. Therefore, there is only 1 net carbon produced to play with for each turn. To create 1 surplus G3P requires 3 carbons, and therefore 3 turns of the Calvin cycle.
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Research is being done testing various activated carbons' ability to store natural gas and hydrogen gas. The porous material acts like a sponge for different types of gases. The gas is attracted to the carbon material via Van der Waals forces. Some carbons have been able to achieve bonding energies of 5–10 kJ per mol.
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The fungus genus Phanerochaete under anaerobic conditions has species with the ability to metabolize some polynuclear aromatic carbons utilizing a peroxidase enzyme.
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Schellman loop. Nitrogen atoms, blue; oxygens, red; carbons, grey. The purple and yellow lines are hydrogen bonds. Side chain and hydrogen atoms omitted.
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Figure 2: (a) Explicit resonance structures for the non-classical 2-norbornyl cation. (b) Common depiction of the 2-norbornyl cation, using dashed lines for partial bonds. Advocates of the non-classical nature of the stable 2-norbornyl cation typically depict the species using either resonance structures or a single structure with partial bonds (see Figure 2). This hypovalent interaction can be imagined as the net effect of i) a partial sigma bond between carbons 1 and 6, ii) a partial sigma bond between carbons 2 and 6, and iii) a partial pi bond between carbons 1 and 2.
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The precursors for graphitizing carbons pass through a fluid stage during pyrolysis (carbonization). This fluidity facilitates the molecular mobility of the aromatic molecules, resulting in intermolecular dehydrogenative polymerization reactions to create aromatic, lamellar (disc- like) molecules. These “associate” to create a new liquid crystal phase, the so-called mesophase. A fluid phase is the dominant requirement for production of graphitizable carbons.
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Commonly, an individual fluorotelomer alcohol molecule is named by the number of carbons that are fluorinated versus the number that are hydrocarbon-based. For example, 8:2 fluorotelomer alcohol would represent a molecule with 8 fluorinated carbons and a 2 carbon ethyl alcohol group. The structure of a fluorotelomer alcohol is most commonly F(CF2)nCH2CH2OH, where n is an even number.
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Ketosynthase, ketoreductase, dehydrates, enol reductases and cyclisases are shown as domains of the Monocerin PKS and methyl transferase is considered to be a tailoring enzyme. Figure 1. Biosyntheis of Monocerin # Formation of an enolate ion on the carbon three carbons away from sulfur allows aldol addition onto the carbonyl six carbons distant along the chain. This produces the secondary alcohol.
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The exact number of carbons varies by species and can be used as an identification aid. Most mycolic acids also contain various functional groups.
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In general, a primary or secondary aliphatic amine separated by 2 carbons from a substituted benzene ring is minimally required for high agonist activity.
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The rates and levels of removal of above cytokines (85–100% removed within 30 minutes) are higher than those observed for comparable activated carbons.
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Carbide-derived carbons can exhibit high surface area and tunable pore diameters (from micropores to mesopores) to maximize ion confinement, increasing pseudocapacitance by faradaic adsorption treatment. CDC electrodes with tailored pore design offer as much as 75% greater specific energy than conventional activated carbons. , a CDC supercapacitor offered a specific energy of 10.1 Wh/kg, 3,500 F capacitance and over one million charge- discharge cycles.
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These changes of ISP-1 resulted in continued improvements in the profile of the compound. To further improve the activity and safety the side chain was shortened from 28 carbons to 14 carbons marked orange on illustration 1. 300x300pxTo find the lead optimization a part of the fatty acid side chain was replaced with 1,4-disubstituted phenyl ring. This was done to decrease the bond rotation.
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4-Methylpentanoic acid is a carboxylic acid of five carbons with methyl substitution at fourth carbon. It is also called 4-methylvaleric acid or isocaproic acid.
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The cycle produces coenzymes NADH and FADH2 through the oxidation of carbons in two cycles. The oxidation of NADH and FADH2 produces GTP from succinyl-CoA synthetase.
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According to IUPAC, carbon atoms forming valine are numbered sequentially starting from 1 denoting the carboxyl carbon, whereas 4 and 4' denote the two terminal methyl carbons.
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Routes begin with phytic acid (Ins(1,2,3,4,6)P6) or its salt, calcium phytate. E.g. Ins(1,3,5)P3 has phosphate groups bound to carbons 1, 3 and 5.
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They found that as the number of carbons increased, so did the enthalpy of activation for the reaction. This indicates that strain within the cyclic transition states is higher if there are more carbons in the ring. Since transannular strain is the largest source of strain in rings this size, the larger enthalpies of activation result in much slower cyclizations due to transannular interactions in the cyclic ethers.
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Delta toxin is quite heat-stable, unlike S. aureus alpha and beta toxins. However, the addition of lecithin specifically prevents delta toxin from lysing cells. Delta toxin activity can also both enhanced and prevented with saturated, straight-chain fatty acids of varying lengths. Phospholipids 13 to 19 carbons in length enhanced the lytic activity of delta toxin, whereas those that were 21 to 23 carbons long were inhibitory.
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Sialoadhesin's variable immunoglobulin domain in complex with a sialylated glycan. Glycan carbons are in purple, protein carbons in green, oxygens in red, nitrogens in blue and hydrogens in white. Siglecs are Type I transmembrane proteins where the NH3+-terminus is in the extracellular space and the COO−-terminus is cytosolic. Each Siglec contains an N-terminal V-type immunoglobulin domain (Ig domain) which acts as the binding receptor for sialic acid.
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General structure of a cardo polymer Cardo polymers are a sub group of polymers where carbons in the backbone of the polymer chain are also incorporated into ring structures. These backbone carbons are quaternary centers. As such, the cyclic side group lies perpendicular to the plane of the polymer chain, creating a looping structure. These rings are bulky structures which sterically hinder the polymers and prevent them from packing tightly.
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Partly for these reasons, they have been the object of much research. In the literature, the bond shared by the three cycles is usually called the "bridge"; the shared carbon atoms are then the "bridgeheads". The notation [x.y.z]propellane means the member of the family whose rings have x, y, and z carbons, not counting the two bridgeheads; or x + 2, y + 2, and z + 2 carbons, counting them.
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Oxanorbornadiene (OND) is a bicyclic organic compound with an oxygen atom bridging the two opposing saturated carbons of 1,4-cyclohexadiene. OND is related to all-carbon bicycle norbornadiene.
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The unique methylation of theophylline corresponds to the following signals: 27.7δ and 29.9δ. The remaining signals correspond to carbons characteristic of the xanthine backbone.Pfleiderer, W. Pteridines. Part CXIX.
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1,1-Ethanedithiol reacts with hydrogen sulfide to form cis/trans-4,7-dimethyl-1,2,3,5,6-pentathiepane, a ring containing five sulfur atoms and two carbons. This has a meaty smell.
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The most popular aqueous phase carbons are the 12×40 and 8×30 sizes because they have a good balance of size, surface area, and head loss characteristics.
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The residual affinity of estrogen esters for the estrogen receptor in bioassays may actually be due to conversion into the parent estrogen, as attempts to prevent or limit this conversion have been found to abolish binding to the estrogen receptor and estrogenicity. In general, the longer the fatty acid ester chain of an estrogen ester, the greater its lipophilicity, and the longer the duration of the estrogen ester with intramuscular injection. It has been said that, via intramuscular injection, the duration of estradiol benzoate (with an ester of length 1 carbon plus a benzene ring) is 2 to 3 days, of estradiol dipropionate (with two esters each of length 2 carbons) is 1 to 2 weeks, of estradiol valerate (ester of 5 carbons) is 1 to 3 weeks, and of estradiol cypionate (ester of 3 carbons plus a cyclopentane ring) is 3 to 4 weeks. Estradiol enantate (ester of 7 carbons) has a duration of around 20 days.
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In organic compounds, the weight percent of hydrocarbon chain often determines the compound's miscibility with water. For example, among the alcohols, ethanol has two carbon atoms and is miscible with water, whereas 1-butanol with four carbons is not. Octanol, with eight carbons, is practically insoluble in water, and its immiscibility leads it to be used as a standard for partition equilibria. The straight-chain carboxylic acids up to butanoic acid (with four carbon atoms) are miscible with water, pentanoic acid (with five carbons) is partly soluble, and hexanoic acid (with six) is practically insoluble, as are longer fatty acids and other lipids; the very long carbon chains of lipids cause them almost always to be immiscible with water.
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Every year humans add 25 billion tons of carbon dioxide to the atmosphere, and over half of it comes from their domestic activity. Attenborough introduces the Carbons, a fictional family occupying an average Western suburban house near a city. Their electrical requirements are supplied via fossil fuels. As Attenborough points out, the Carbons are not bad people, but as Westerners, they have one of the most energy-hungry lifestyles on the planet.
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Trenbolone acetate is a modified form of nandrolone. The structure of trenbolone acetate is a 19-nor classification, which represents a structural change of the testosterone hormone. Trenbolone acetate lacks a carbon atom at the 19 position and carries a double bond at carbons 9 and 11. The position of these carbons slows its metabolism, which greatly increases its binding affinity to the AR, and inhibits it from undergoing aromatization into the corresponding estrogenic metabolite.
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Ecology & Society, 23(4), 42–65. Oceans alleviate the impact of climate change and absorb around 23% of the annual emissions of various forms of carbons, the most concerning being carbon dioxide. Because of the absorbed carbons, seawater becomes more acidic and its pH levels drops significantly. Ocean acidification puts coral reefs and other species in danger which impacts the marine food chain and ecosystem services including fisheries, transportation and even tourism.
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An oxazolidine is a five-membered ring compound consisting of three carbons, a nitrogen, and an oxygen. The oxygen and NH are the 1 and 3 positions, respectively. In oxazolidine derivatives, there is always a carbon between the oxygen and the nitrogen (or it would be an isoxazolidine).Dr Neil G Carter OXAZOLIDINE DILUENTS: REACTING FOR THE ENVIRONMENT Industrial Copolymers Limited All of the carbons in oxazolidines are reduced (compare to oxazole and oxazoline).
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Notice that the carbons at the fused rings are treated differently than regular benzene carbons. Not only can the BGIT be used to confirm experimental values, but can also to confirm theoretical values. Scheme showing a simple application of BGIT to rationalize relative thermodynamics between an alkene (top) and a ketone (bottom). BGIT also can be used for comparing the thermodynamics of simplified hydrogenation reactions for alkene (2-methyl-1-butene) and ketone(2-butanone).
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Later the company underwent several changes and expansions in the product range which include Powdered Activated Carbons and Impregnated Activated Carbons. Between the years 2001 and 2004 CarboTech Aktivkohlen GmbH had spin-off to Rütgers Chemicals AG, Rütgers CarboTech GmbH and finally in the year 2005, the company was taken over by International Chemical Investors Group.IC-Investors News, June 2005 Later in the year 2006, the name of the company changed to CarboTech AC GmbH.
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In cancer cells, the ratio between dimeric and tetrameric forms of PKM2 determines what happens to glucose carbons. If PKM2 is in the dimeric form, glucose is channeled into synthetic processes such as nucleic acid, amino acid, or phospholipid synthesis. If A-Raf is present, PKM2 is more likely to be in the tetrameric form. This causes more glucose carbons to be converted to pyruvate and lactate, producing energy for the cell.
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Substrate length for mDECR catalysis is thought to be limited at 20 carbons, at which this very long chain fatty acid is first partially oxidized by pDECR in the peroxisome.
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Some companies are also developing gasification technologies to utilize poultry litter as a fuel for electrical and heating applications, along with producing valuable by-products including activated carbons and fertilizers.
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Some of the world's main producers of electroconductive carbon black include UNIPETROL (Chezacarb), CABOT Corporation (Vulcan), DEGUSSA (Printex), AKZO-Nobel (Ketjenblack), TIMCAL (Ensaco), BIRLA CARBON (Conductex), ORION ENGINEERED CARBONS (XPB).
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Unlike benzene, Dewar benzene is not flat because the carbons where the rings join are bonded to four atoms rather than three. These carbons tend toward tetrahedral geometry, and the two cyclobutene rings make an angle where they are cis-fused to each other. The compound has nevertheless considerable strain energy and reverts to benzene with a chemical half-life of two days. This thermal conversion is relatively slow because it is symmetry forbidden based on orbital symmetry arguments.
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The deuterium content of the sugars from the above plant species are not distinctive. In C3 plants, Hydrogens attached to Carbons in 4 and 5 positions of the glucose typically come from NADPH in the photosynthetic pathway, and are found to be more D-enriched. Whereas in C4 plants, Hydrogens attached to Carbons 1 and 6 positions are more D-enriched. D-enrichment patterns in CAM species tend to be closer to that in C3 species.
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A micrograph of activated charcoal (GAC) under scanning electron microscope Granular activated carbon (GAC) has a relatively larger particle size compared to powdered activated carbon and consequently, presents a smaller external surface. Diffusion of the adsorbate is thus an important factor. These carbons are suitable for adsorption of gases and vapors, because they diffuse rapidly. Granulated carbons are used for water treatment, deodorization and separation of components of flow system and are also used in rapid mix basins.
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Carbide- derived carbons with a mesoporous structure remove large molecules from biofluids. As other carbons, CDCs possess good biocompatibility. CDCs have been demonstrated to remove cytokines such as TNF-alpha, IL-6, and IL-1beta from blood plasma. These are the most common receptor-binding agents released into the body during a bacterial infection that cause the primary inflammatory response during the attack and increase the potential lethality of sepsis, making their removal a very important concern.
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Polynuclear aromatic carbons susceptibility to degradation is related to the number of aromatic rings within the compound. Compounds with two or three rings are degraded at an effective rate, compounds possessing four or more rings can be more resilient to bioremediation efforts. Degradation of polynuclear aromatic carbons with less than four rings is accomplished by various aerobic microbes present in the soil. For larger compounds the only metabolic mode that has shown to be effective is cometabolism.
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The alkene carbon-carbon double bond is made from two sp trigonally hybridized carbons, where one of the carbon-carbon bonds is a sigma bond and the other is a pi bond.
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The reaction of furfural and aniline produces a bright pink color. Hexoses, which are sugars which contain six carbons, are not dehydrated to furfural, and so they do not produce a pink color.
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Fusicoccins contains three fused carbon rings and another ring which contains an oxygen atom and five carbons. Fusicoccin was and is extensively used in research regarding the plant hormone auxin and its mechanisms.
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Like tartaric acid, calcium tartrate has two asymmetric carbons, hence it has two chiral isomers and a non-chiral isomer (meso-form). Most calcium tartrate of biological origin is the chiral levorotatory (–) isomer.
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This method also produces a homological series of n-alkanes of up to 35 carbons and coke, as well. The assumption that diamandoid compounds can be synthesized through thermal cracking requires more verification.
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Because the phosphate group has two separate bonds to the ribose sugar, it forms a cyclic ring. The atom numbering convention is used to identify the carbons and nitrogens within a cyclic nucleotide.
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Brush Electric installed about eighty percent of the nation's arc-lighting systems during the early 1880s. Arc lights need carbon electrodes called carbon points (or simply "carbons") to work. Each carbon would only last on the order of several hours, and then needed to be replaced. In 1881, the use of carbons had become so widespread, and the profits had become so large, that it enticed W. H. Boulton, the foreman of the Brush Electric Company's carbon department, to leave Brush Electric.
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H. Marsh and M.A. Diez (1994) " Mesophase of Graphitizable Carbons" In: Shibaev V.P., Lam L. (eds) Liquid Crystalline and Mesomorphic Polymers. Springer, New York, NY Non-graphitizing carbons generally do not pass through a fluid stage during carbonization. Since the time of Rosalind Franklin, researchers have put forward a number of models for their structure . Oberlin and colleagues emphasised the role of basic structural units (BSU), made of planar aromatic structures consisting of less than 10-20 rings, with four layers or fewer.
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The preparation of glassy carbon involves subjecting the organic precursors to a series of heat treatments at temperatures up to 3000 °C. Unlike many non-graphitizing carbons, they are impermeable to gases and are chemically extremely inert, especially those prepared at very high temperatures. It has been demonstrated that the rates of oxidation of certain glassy carbons in oxygen, carbon dioxide or water vapor are lower than those of any other carbon. They are also highly resistant to attack by acids.
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Common sources of plant oils containing ALA include walnut, edible seeds, clary sage seed oil, algal oil, flaxseed oil, Sacha Inchi oil, Echium oil, and hemp oil, while sources of animal omega−3 fatty acids EPA and DHA include fish, fish oils, eggs from chickens fed EPA and DHA, squid oils and krill oil. Mammals are unable to synthesize the essential omega−3 fatty acid ALA and can only obtain it through diet. However, they can use ALA, when available, to form EPA and DHA, by creating additional double bonds along its carbon chain (desaturation) and extending it (elongation). Namely, ALA (18 carbons and 3 double bonds) is used to make EPA (20 carbons and 5 double bonds), which is then used to make DHA (22 carbons and 6 double bonds).
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A stationary phase of polar functionally bonded silicas with short carbons chains frequently makes up the solid phase. This stationary phase will adsorb polar molecules which can be collected with a more polar solvent.
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Namely, five of the carbons have one hydroxyl functional group (–OH) each, connected by a single bond, and one has an oxo group (=O), forming a carbonyl group (C=O). The remaining bonds of the carbon atoms are satisfied by seven hydrogen atoms. The carbons are commonly numbered 1 to 6 starting at the end closest to the carbonyl. Hexoses are extremely important in biochemistry, both as isolated molecules (such as glucose and fructose) and as building blocks of other compounds such as starch, cellulose, and glycosides.
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Carbon microballs made from glycose via hydrothermal carbonization, that have been processed with CO2 for 6 hours to change surface properties. SEM image from University of Tartu. Hydrothermal carbonization (HTC) (also referred to as "aqueous carbonization at elevated temperature and pressure") is a chemical process for the conversion of organic compounds to structured carbons. It can be used to make a wide variety of nanostructured carbons, simple production of brown coal substitute, synthesis gas, liquid petroleum precursors and humus from biomass with release of energy.
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One probe for testing whether or not the 2-norbornyl cation is non-classical is investigating the inherent symmetry of the cation. Many spectroscopic tools, such as nuclear magnetic resonance spectroscopy (NMR spectroscopy) and Raman spectroscopy, give hints about the reflectional and rotational symmetry present in a molecule or ion. Each of the three proposed structures of the 2-norbornyl cation illustrates a different molecular symmetry. The non-classical form contains a reflection plane through carbons 4, 5, 6, and the midpoint of carbons 1 and 2.
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Chemical structure of α-linolenic acid (ALA), a fatty acid with a chain of 18 carbons with three double bonds on carbons numbered 9, 12, and 15. Note that the omega (ω) end of the chain is at carbon 18, and the double bond closest to the omega carbon begins at carbon 15 = 18−3. Hence, ALA is a ω−3 fatty acid with ω = 18. The terms ω–3 ("omega–3") fatty acid and n–3 fatty acid are derived from organic nomenclature.
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Natural bilanes usually have side chains substituted on the two carbons in each pyrrole ring that are not adjacent to the nitrogens. Artificial bilanes may be substituted on the bridging carbons (called meso positions). The parent (unsubstituted) bilane is difficult to prepare and unstable,Claudia Ryppa, Mathias O. Senge, Sabine S. Hatscher, Erich Kleinpeter, Philipp Wacker, Uwe Schilde, and Arno Wiehe (2005): "Synthesis of Mono‐ and Disubstituted Porphyrins: A‐ and 5,10‐A2‐Type Systems". Chemistry, A European Journal, volume 11, issue 11, pages 3427-3442.
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1,1,1,3,3,3-Hexachloropropane is a compound of chlorine, hydrogen, and carbon, with chemical formula , specifically . Its molecule can be described as that of propane with chlorine atoms substituted for the six hydrogen atoms on the extremal carbons.
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Peptoids, or poly-N-substituted glycines, are a class of peptidomimetics whose side chains are appended to the nitrogen atom of the peptide backbone, rather than to the α-carbons (as they are in amino acids).
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Thus, the reactive ends are not available for polymerisation, thereby decreasing competition for the cyclisation process. Diesters possessing 10 or more carbons undergo cyclisation very easily.REACTIONS, REARRANGEMENTS, AND REAGENTS by S N Sanyal, Bharati Bhavan publishers, .
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ALOX15 and Alox15 enzymes are non- heme, iron-containing dioxygenases. They commonly catalyze the attachment of molecular oxygen as a peroxy residue to polyunsaturated fatty acids (PUFA) that contain two carbon-carbon double bonds that for the human ALOX15 are located between carbons 10 and 9 and 7 and 6 as numbered counting backward from the last or omega (i.e. ω) carbon at the methyl end of the PUFA (these carbons are also termed ω-10 and ω-9 and ω-7 and ω-6). In PUFAs that do not have a third carbon-carbon double bound between their ω-13 and ω-12 carbons, human ALOX15 forms ω-6 peroxy intermediates; in PUFAs that do have this third double bound, human ALOX15 makes the ω-6 peroxy intermediate but also small amounts of the ω-9 peroxy intermediate.
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Cambridge Structural Database The C–C bonds to the carbons adjacent to the sulfur are about 1.34 Å, the C–S bond length is around 1.70 Å, and the other C–C bond is about 1.41 Å.
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Nefopam is a cyclized analogue of orphenadrine, diphenhydramine, and tofenacin, with each of these compounds different from one another only by the presence of one or two carbons. The ring system of nefopam is a benzoxazocine system.
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Another classification considers the position of the double bonds relative to the end of the chain (opposite to the carboxyl group). The position is denoted by "ω−k" or "n−k", meaning that there is a double bond between carbons k and k+1 counted from 1 at that end. For example, alpha-Linolenic acid is a "ω−3" or "n−3" acid, meaning that there is a double bond between the third and fourth carbons, counted from that end; that is, its structural formula ends with –CH=CH––.
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Glucose can exist in both a straight-chain and ring form. In its fleeting open-chain form, the glucose molecule has an open (as opposed to cyclic) and unbranched backbone of six carbon atoms, C-1 through C-6; where C-1 is part of an aldehyde group H(C=O)−, and each of the other five carbons bears one hydroxyl group −OH. The remaining bonds of the backbone carbons are satisfied by hydrogen atoms −H. Therefore, glucose is both a hexose and an aldose, or an aldohexose.
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The modest acidity of carbons adjacent to the sulfonyl group has made sulfones useful for organic synthesis. Upon removal of the sulfonyl group with desulfonylation or reductive elimination, the net result is the formation of a carbon-carbon bond single or double bond between two unfunctionalized carbons, a ubiquitous motif in synthetic targets. In a synthesis of (–)-anthoplalone, Julia olefination was used to establish the (E)-alkene in the target. (12)File:DesulfSynth1.png Reductive desulfonylation is employed when the establishment of a carbon-carbon single bond is the goal.
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The stereoselectivity of 1,3-dipolar cycloaddition reactions between carbonyl ylide dipoles and alkenyl dipolarophiles has also been closely examined. For alkynyl dipolarophiles, stereoselectivity is not an issue as relatively planar sp2 carbons are formed, while regioselectivity must be considered (see image of the Products of the 1,3-Dipolar Cycloaddition Reaction Between Carbonyl Ylide Dipoles and Alkenyl or Alkynyl Dipolarophiles). However, for alkenyl dipolarophiles, both regioselectivity and stereoselectivity must be considered as sp3 carbons are generated in the product species. 1,3-dipolar cycloaddition reactions between carbonyl ylide dipoles and alkenyl dipolarophiles can generate diastereomeric products.
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One of the first historical QSAR applications was to predict boiling points. It is well known for instance that within a particular family of chemical compounds, especially of organic chemistry, that there are strong correlations between structure and observed properties. A simple example is the relationship between the number of carbons in alkanes and their boiling points. There is a clear trend in the increase of boiling point with an increase in the number carbons, and this serves as a means for predicting the boiling points of higher alkanes.
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A major strength of any eusocial insect is the ability to communicate amongst one another. Often, this method of communication comes in the form of chemical signals between members of the same colony. In particular, cuticular hydrocarbon levels are thought to be of great importance to S. quadripunctata communication and can vary greatly according to age, sex and caste. Hydrocarbons in the stingless bee can vary in length from nonadecane with nineteen carbons to tritriacontane with thirty- three carbons, as discovered in a study conducted by Nunes et al. (2009).
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The carbons of the double bond become pyramidal, which allows preserving some p orbital alignment—and hence pi bonding. The other two attached groups remain at a larger dihedral angle. This contradicts a common textbook assertion that the two carbons retain their planar nature when twisting, in which case the p orbitals would rotate enough away from each other to be unable to sustain a pi bond. In a 90°-twisted alkene, the p orbitals are only misaligned by 42° and the strain energy is only around 40 kcal/mol.
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In the pentose, the carbon closest to the carbonyl group is labeled C-1. When a pentose is connected to a nitrogenous base, carbon atom numbering is distinguished with a prime (') notation, which differentiates these carbons from the atom numbering of the nitrogenous base. Therefore, for cAMP, 3’5’-cyclic adenosine monophosphate indicates that a single phosphate group forms a cyclic structure with the ribose group at its 3’ and 5’ carbons, while the ribose group is also attached to adenosine (this bond is understood to be at the 1’ position of the ribose).
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Being polyketides, the okadaic acid family of molecules are synthesized by dinoflagellates via polyketide synthase (PKS). However unlike the majority of polyketides, the dinoflagellate group of polyketides undergo a variety of unusual modifications. Okadaic acid and its derivatives are some of the most well studied of these polyketides, and research on these molecules via isotopic labeling has helped to elucidate some of those modifications. Okadaic acid is formed from a starter unit of glycolate, found at carbons 37 and 38, and all subsequent carbons in the chain are derived from acetate.
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The number of distinct stereoisomers with the same diagram is bounded by 2c, where c is the total number of chiral carbons. The Fischer projection is a systematic way of drawing the skeletal formula of an acyclic monosaccharide so that the handedness of each chiral carbon is well specified. Each stereoisomer of a simple open-chain monosaccharide can be identified by the positions (right or left) in the Fischer diagram of the chiral hydroxyls (the hydroxyls attached to the chiral carbons). Most stereoisomers are themselves chiral (distinct from their mirror images).
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For example, dATP stands for deoxyribose adenine triphosphate. NTPs are the building blocks of RNA, and dNTPs are the building blocks of DNA. The carbons of the sugar in a nucleoside triphosphate are numbered around the carbon ring starting from the original carbonyl of the sugar. Conventionally, the carbon numbers in a sugar are followed by the prime symbol (‘) to distinguish them from the carbons of the nitrogenous base. The nitrogenous base is linked to the 1’ carbon through a glycosidic bond, and the phosphate groups are covalently linked to the 5’ carbon.
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Two websites are available for finding and examining β bulge loops in proteins, Motivated Proteins: and PDBeMotif: . Type 1 beta bulge loop. Main chain atoms only of hexapeptide; no hydrogen atoms. Carbons grey, oxygens red and nitrogens blue.
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1,2-Dihydro-1,2-azaborine is an aromatic chemical compound with properties intermediate between benzene and borazine. Its chemical formula is CBNH. It resembles a benzene ring, except that two adjacent carbons are replaced by nitrogen and boron, respectively.
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2-Chloropyridine reacts with nucleophiles to generate pyridine derivatives substituted at the second and fourth carbons on the heterocycle. Therefore, many reactions using 2-chloropyridine generate mixtures of products which require further workup to isolate the desired isomer.
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Octanols are alcohols with the formula C8H17OH. A simple and important member is 1-octanol, with an unbranched chain of carbons. Other commercially important octanols are 2-octanol and 2-ethylhexanol. There are 89 possible isomers of octanol.
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This atom is sp2 hybridized and has one lone pair in an sp2 orbital and a second lone pair in a p orbital, overlapping with the p orbitals of adjacent carbons. This results in a pi bond formation.
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Many derivatives of selenopyrylium are known with side chains attached to carbons 2,3 or 6. Examples include 4-(p-dimethylaminophenyl)selenopyridinium, 2,6-diphenylselenopyridinium, 4-methyl-2,6-diphenylselenopyrylium, 2,4,6-triphenylselenopyrylium, 2,6-diphenyl-4-(p-dimethylaminophenyl)selenopyrylium. 2,6-di-tert- butylselenopyrylium.
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In the typical porphyrin biosynthesis pathway, four molecules of porphobilinogen are concatenated by carbons 2 and 5 of the pyrrole ring (adjacent to the nitrogen atom) into hydroxymethyl bilane by the enzyme porphobilinogen deaminase, also known as hydroxymethylbilane synthase.
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The general formula is then where s= m+n+p+q. In particular, the basic compound has those carbons connected by four methylene bridges (m=n=p=q=1), and its name within that family is therefore [1.1.1.1]pagodane.
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Unlike the IMHR, radical cyclization does not require the coupling of two sp2-hybridized carbons. In some cases, the results of radical cyclization and IMHR are complementary.Ishibashi, H.; Ito, K.; Hirano, T.; Tabuchi, M.; Ikeda, M. Tetrahedron 1993, 49, 4173.
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The molecular weight of this compound is 271,48 g/mol and its molecular formula is C17H37NO, which means it has 17 carbons. In relation to its appearance, it has a powder form. Other physical and chemical properties are not certainly known.
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Oxazolidines are a five-membered ring compounds consisting of three carbons, a nitrogen, and an oxygen. The oxygen and NH are the 1 and 3 positions, respectively. In oxazolidine derivatives, there is always a carbon between the oxygen and the nitrogen.
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The vinyl cation has an intense IR peak at 1987 cm−1 for the C=C+ stretching. More importantly, the bond angles between the vinyl cation carbons and the first carbon of the alkyl substituted was measured to be approximately 180o.
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The value of its spectral slope suggests that the surface of this object can have pure methane ices (like in the case of Pluto) and highly processed carbons, including some amorphous silicates. Its spectral slope is similar to that of .
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Steroid skeleton. Carbons 18 and above can be absent. Hydroxycorticosteroids (OHCSs) are corticosteroids that have an additional hydroxy (-OH) group. There are two main positions where the hydroxy group may be added: at carbon atom 11, and at carbon atom 17.
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Sapienic acid has 16 carbons, is found in the skin, and is a cis6-mono-unsaturated fatty acid. C15H29CO2H, IUPAC organization name (Z)-6-Hexadecenoic acid, n-10, numerical expression 16: 1, molecular weight 254.41. CAS Registry Number 17004-51-2.
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Oxidative cleavage of the double bond of this intermediate would result in the loss of the terminal three carbons producing the C-17 tetracyclic enone acid unit. An N-acyltransferase reaction of tetracyclic enone and aminobenzoic acid would lead to platensimycin.
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The triazinanes have six- membered Cyclohexane-like ring but with three carbons replaced by nitrogens. The three isomers of triazinane are distinguished by the positions of their nitrogen atoms, and are referred to as 1,2,3-triazinane, 1,2,4-triazinane, and 1,3,5-triazinane.
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Zilpaterol has two chiral carbons and consequently four optical enantiomers. These enantiomers are: (6R,7R)-, (6R,7S)-, (6S,7R)- and (6S,7S)-. RU 42173 corresponds to racemic trans-zilpaterol hydrochloride, a mixture of the (6R,7R)-(−)- and (6S,7S)-(+)-enantiomers.
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CES1 oxidizes the tertiary amide carbonyl carbons of edoxabans to carboxylic acid groups. CYP3A4 and CYP3A5 oxidize edoxabans via hydroxylation or demethylation. In hydrolysis, 2-amino-5-chloropyridine moiety of edoxaban is removed. Glucuronidation occurs to a lesser extend via glucuronosyltransferases.
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Activated carbons are complex products which are difficult to classify on the basis of their behaviour, surface characteristics and other fundamental criteria. However, some broad classification is made for general purposes based on their size, preparation methods, and industrial applications.
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Tannins are a mixture of large and medium size molecules. Carbons with a combination of macropores and mesopores adsorb tannins. The ability of a carbon to adsorb tannins is reported in parts per million concentration (range 200 ppm–362 ppm).
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Some carbons have a mesopore (20 Å to 50 Å, or 2 to 5 nm) structure which adsorbs medium size molecules, such as the dye methylene blue. Methylene blue adsorption is reported in g/100g (range 11–28 g/100g).
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World's largest reactivation plant located in , Belgium. Activated carbon reactivation center in Roeselare, Belgium. The reactivation or the regeneration of activated carbons involves restoring the adsorptive capacity of saturated activated carbon by desorbing adsorbed contaminants on the activated carbon surface.
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Proline residues lack NH groups so are rare in nests. About one in 12 of amino acid residues in proteins, on average, belongs to a nest. RL nest bound to an egg oxygen. carbons grey, oxygens red and nitrogens blue.
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The long carbon chain contained in Butyrolactol A was determined to originate from the acetate pathway by carbon-14 labeling acetate, the two carbon precursor for polyketide synthase. The presence of PKS genes from the Streptomyces family further confirmed the mechanism of acetyl-group based chain elongation. Carbons 1-8 were confirmed to originate from glycolytic pathway intermediate hydroxymalonyl-ACP (Figure). This is supported by 13C labeling, where 13C-13C couplets were present for the aforementioned carbons, as well as gene sequencing, which found genes coding for enzymes involved in hydroxymalonyl- ACP formation in zwittermicin biosynthesis.
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The final partial structure consists of a thiazoline ring with a terminal alkene substituent, as determined by electron ionization mass spectrometry (EI-MS) and 13C NMR. The chemical shifts of ring carbons adjacent to the sulfur and nitrogen heteroatoms were compared to 13C NMR data from model compounds. This allowed for the determination of these heteroatoms' locations in the ring, and subsequently the existence of the thiazoline ring itself. With these partial structures established, their connectivity was evaluated via HMBC spectroscopy, a 2D NMR technique which allows for the determination of heteronuclear J-coupling values for nonadjacent carbons and protons.
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In a flame ionization detector (FID), electrodes are placed adjacent to a flame fueled by hydrogen / air near the exit of the column, and when carbon containing compounds exit the column they are pyrolyzed by the flame. This detector works only for organic / hydrocarbon containing compounds due to the ability of the carbons to form cations and electrons upon pyrolysis which generates a current between the electrodes. The increase in current is translated and appears as a peak in a chromatogram. FIDs have low detection limits (a few picograms per second) but they are unable to generate ions from carbonyl containing carbons.
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An α-glycosidic bond is formed when both carbons have the same stereochemistry, whereas a β-glycosidic bond occurs when the two carbons have different stereochemistry. One complicating issue is that the alpha and beta conformations were originally defined based on the relative orientation of the major constituents in a Haworth projection. In this case, for D-sugars, a beta conformation would see the major constituent at each carbon drawn above the plane of the ring (nominally the same conformation), while alpha would see the anomeric constituent below the ring (nominally opposite conformations). For L-sugars, the definitions would then, necessarily, reverse.
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For example, the triketose H(CHOH)(C=O)(CHOH)H (glycerone, dihydroxyacetone) has no stereogenic center, and therefore exists as a single stereoisomer. The other triose, the aldose H(C=O)(CHOH)2H (glyceraldehyde), has one chiral carbon — the central one, number 2 — which is bonded to groups −H, −OH, −C(OH)H2, and −(C=O)H. Therefore, it exists as two stereoisomers whose molecules are mirror images of each other (like a left and a right glove). Monosaccharides with four or more carbons may contain multiple chiral carbons, so they typically have more than two stereoisomers.
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Porous carbons containing several types of inorganic impregnate such as iodine, silver, cations such as Al, Mn, Zn, Fe, Li, Ca have also been prepared for specific application in air pollution control especially in museums and galleries. Due to its antimicrobial and antiseptic properties, silver loaded activated carbon is used as an adsorbent for purification of domestic water. Drinking water can be obtained from natural water by treating the natural water with a mixture of activated carbon and Al(OH)3, a flocculating agent. Impregnated carbons are also used for the adsorption of Hydrogen Sulfide(H2S) and thiols.
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As all of the pore volume may not be available for adsorption in a particular waste water application, and as some of the adsorbate may enter smaller pores, it is not a good measure of the worth of a particular activated carbon for a specific application. Frequently, this parameter is useful in evaluating a series of active carbons for their rates of adsorption. Given two active carbons with similar pore volumes for adsorption, the one having the higher molasses number will usually have larger feeder pores resulting in more efficient transfer of adsorbate into the adsorption space.
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Having originated as the by-product of industrial metal chloride synthesis, CDC has certainly a potential for large-scale production at a moderate cost. Currently, only small companies engage in production of carbide-derived carbons and their implementation in commercial products. For example, Skeleton, which is located in Tartu, Estonia, and Carbon-Ukraine, located in Kiev, Ukraine, have a diverse product line of porous carbons for supercapacitors, gas storage, and filtration applications. In addition, numerous education and research institutions worldwide are engaged in basic research of CDC structure, synthesis, or (indirectly) their application for various high-end applications.
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The common dietary monosaccharides galactose, glucose and fructose are all reducing sugars. Disaccharides are formed from two monosaccharides and can be classified as either reducing or nonreducing. Nonreducing disaccharides like sucrose and trehalose have glycosidic bonds between their anomeric carbons and thus cannot convert to an open-chain form with an aldehyde group; they are stuck in the cyclic form. Reducing disaccharides like lactose and maltose have only one of their two anomeric carbons involved in the glycosidic bond, while the other is free and can convert to an open-chain form with an aldehyde group.
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Various DEPT spectra of propyl benzoate From top to bottom: 135°, 90° and 45° Distortionless enhancement by polarization transfer (DEPT) is an NMR method used for determining the presence of primary, secondary and tertiary carbon atoms. The DEPT experiment differentiates between CH, CH2 and CH3 groups by variation of the selection angle parameter (the tip angle of the final 1H pulse): 135° angle gives all CH and CH3 in a phase opposite to CH2; 90° angle gives only CH groups, the others being suppressed; 45° angle gives all carbons with attached protons (regardless of number) in phase. Signals from quaternary carbons and other carbons with no attached protons are always absent (due to the lack of attached protons). The polarization transfer from 1H to 13C has the secondary advantage of increasing the sensitivity over the normal 13C spectrum (which has a modest enhancement from the nuclear overhauser effect (NOE) due to the 1H decoupling).
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For example, cyanide is a key catalyst in the benzoin condensation, a classical example of polarity inversion. Mechanism of the benzoin condensation The net result of the benzoin reaction is that a bond has been formed between two carbons that are normally electrophiles.
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This location afforded the company greatly increased capacity along with favorable shipping facilities and options. By 1885, the Boulton Carbon was the second largest carbon company in the US, behind only Brush Electric. Boulton produced both plain and the copper-coated carbons.
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Fullerene molecules are composed of a C60 close-caged structure, that allows for hydrogenation of the double bonded carbons leading to a theoretical C60H60 isomer with a hydrogen content of 7.7 wt%. However, the release temperature in these systems is high (600 °C).
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1,2-Difluoroethane is a saturated hydrofluorocarbon containing an atom of fluorine attached to each of two carbons atoms. The formula can be written CH2FCH2F. It is an isomer of 1,1-Difluoroethane. It has a HFC name of HFC-152 with no letter suffix.
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Bi[5]prismane (left) and tri[4]prismane The polyprismanes consist of multiple prismanes stacked base-to-base. The carbons at each intermediate level—the n-gon bases where the prismanes fuse to each other—have no hydrogen atoms attached to them.
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Aromatic carbons are thus relatively easy to exchange. Many of these reactions have a strong temperature dependence, with higher temperatures typically accelerating exchange. However, different mechanisms may prevail at each temperature window. Ionic exchange, for example, has the most significance at low temperatures.
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This can also be explained by the structure of cicutoxin, it consists of 17 carbons, which is hydrophobic. It also has 3 double bonds, 2 triple bonds and two hydroxyl groups, which make the toxin very reactive and not easy to excrete.
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Key residues (two Arg and one His) and substrates shown. The 4.2 Å distance is between the carbons undergoing hydride transfer. From 2G76 rendering of PHGDH crystallized with NAD+ and D-malate. PHGDH is allosterically regulated by its downstream product, L-serine.
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The end products of the remediation for hydrocarbons are Carbon Dioxide and water. Hydrocarbons vary in ease of degradation based on their structure. Long chain aliphatic carbons are the most effectively degraded. Short chained, branched, and quaternary aliphatic hydrocarbons are less effectively degraded.
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If there are multiple chiral carbons, e.g. (1R,4S), a number specifies the location of the carbon preceding each configuration. The R / S system also has no fixed relation to the system. For example, the side-chain one of serine contains a hydroxyl group, -OH.
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He also composed mosaics of painted wood, which he transformed in enormous stamps. Then he started to destroy his works, dissect them and put them in small caged. He also burned his works, creating the Carboni (Carbons), i.e. carbonizzate partly painted with bright colors.
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Some parent C29 to C32 diacids but with methyl groups on the carbons C-13 and C-16 have been isolated and characterized from the lipids of thermophilic anaerobic eubacterium Themanaerobacter ethanolicus. The most abundant diacid was the C30 a,ω-13,16-dimethyloctacosanedioic acid.
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The report found that longer carbon chains (16–18) were less irritating to the skin than chains of 12–15 carbons in length. In addition, concentrations below 1% were essentially non-irritating while concentrations greater than 10% produced moderate to strong irritation of the skin.
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The most efficient substrates are those similar to glucose and xylose, having equatorial hydroxyl groups at the third and fourth carbons. The current model for the mechanism of glucose isomerase is that of a hydride shift based on X-ray crystallography and isotope exchange studies.
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Dioxins with no lateral (2, 3, 7, and 8) chlorines, which thus contain hydrogen atoms on adjacent pairs of carbons, can more readily be oxidized by cytochromes P450. The oxidized dioxins can then be more readily excreted rather than stored for a long time.
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1,3-Bisphosphoglycerate is the conjugate base of 1,3-bisphosphoglyceric acid. It is phosphorylated at the number 1 and 3 carbons. The result of this phosphorylation gives 1,3BPG important biological properties such as the ability to phosphorylate ADP to form the energy storage molecule ATP.
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The diazinanes have six- membered cyclohexane-like ring but with two carbons replaced by nitrogens. The three isomers of triazinane are distinguished by the positions of their nitrogen atoms, and are referred to as 1,2-diazinane, 1,3-diazinane, and 1,4-diazinane (more commonly called piperazine).
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Of the three stereoisomers, two are enantiomers (levo- and dextro-2,3-butanediol) and one is a meso compound. The enantiomeric pair have (2R, 3R) and (2S, 3S) configurations at carbons 2 and 3, while the meso compound has configuration (2R, 3S) or, equivalently, (2S, 3R).
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Graphite conductive agent: KS-6, KS-15, SFG-6, SFG-15, etc. CNTs: the incorporation of CNTs as a conductive additive at a lower weight loading than conventional carbons, like carbon black and graphite, presents a more effective strategy to establish an electrical percolation network.
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Buchanan, G. O.; Williams, P. G.; Feling, R. H.; Kauffman, C. A.; Jensen, P. R.; Fenical, W. Org. Lett. 2005, 7, pp. 2731-2734. The structures and absolute stereochemistries of both metabolites were elucidated using a combination of NMR spectroscopy and X-ray crystallography, and are considered unique for two reasons: \- both compounds appear to be polyketides and therefore derived from acetate units, \- the number of oxidized carbons is amazing, with 21 of 24 carbons either oxygenated or sp2 - hybridized. The complex aromatic structure of the sporolides is hypothesized to be derived from an unstable nine-membered ring enediyne precursor, which undergoes Bergman cyclization to generate a p-benzyne intermediate.
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It can be made from natural or synthetic sources. Other carbon materials used in CDI research are, for example, ordered mesoporous carbon, carbon aerogels, carbide-derived carbons, carbon nanotubes, graphene and carbon black. Recent work argues that micropores, especially pores < 1.1 nm are the most effective for salt adsorption in CDI. In order to mitigate the drawbacks associated with mass transfer and electric double layer overlapping, and simultaneously harness the benefits of higher surface area and higher electric fields that come with microporous structure, innovative ongoing efforts have attempted to integrate the advantages of micropores and mesopores by fabricating hierarchical porous carbons (HPCs) that possess multi levels of porosities.
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Numbered ribose carbons on cytidine. Molecular biologists use several shorthand terms when referring to nucleic acid molecules, such as DNA and RNA, collectively referred to as nucleic acid nomenclature. The most common is the representation of the base pairs as letters--an adenine nucleotide is abbreviated as A, guanine as G, cytosine as C, thymine as T, and in RNA, uracil as U. Additionally, the positions of the carbons in the ribose sugar that forms the backbone of the nucleic acid chain are numbered, and are used to indicate the direction of nucleic acids (5'->3' versus 3'->5'). This is referred to as directionality.
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Nucleic acid types differ in the structure of the sugar in their nucleotides–DNA contains 2'-deoxyribose while RNA contains ribose (where the only difference is the presence of a hydroxyl group). Also, the nucleobases found in the two nucleic acid types are different: adenine, cytosine, and guanine are found in both RNA and DNA, while thymine occurs in DNA and uracil occurs in RNA. The sugars and phosphates in nucleic acids are connected to each other in an alternating chain (sugar- phosphate backbone) through phosphodiester linkages. In conventional nomenclature, the carbons to which the phosphate groups attach are the 3'-end and the 5'-end carbons of the sugar.
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The HNCO contains the carbonyl carbon chemical shift from only the preceding residue, but is much more sensitive than HN(CA)CO. These experiments allow each 1H-15N peak to be linked to the preceding carbonyl carbon, and sequential assignment can then be undertaken by matching the shifts of each spin system's own and previous carbons. The HNCA and HN(CO)CA works similarly, just with the alpha carbons (Cα) rather than the carbonyls, and the HNCACB and the CBCA(CO)NH contains both the alpha carbon and the beta carbon (Cβ). Usually several of these experiments are required to resolve overlap in the carbon dimension.
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Several models exist to describe chiral induction at carbonyl carbons during nucleophilic additions. These models are based on a combination of steric and electronic considerations and are often in conflict with each other. Models have been devised by Cram (1952), Cornforth (1959), Felkin (1969) and others.
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Fructose 1,6-bisphosphate, also known as Harden-Young ester, is fructose sugar phosphorylated on carbons 1 and 6 (i.e., is a fructosephosphate). The β-D-form of this compound is common in cells. Upon entering the cell, most glucose and fructose is converted to fructose 1,6-bisphosphate.
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General scheme for electrophilic attack on acetylene. Adapted from Acid-catalyzed hydration of alkynes through vinyl cation intermediate. Adapted from A vinyl cation intermediate is possibly formed when electrophilic moieties attack unsaturated carbons. This can be achieved in the reaction of electrophiles with alkynes or allenes.
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Carbenium ions are classified as primary, secondary, or tertiary depending on whether the number of carbon atoms bonded to the ionized carbon is 1, 2, or 3. (Ions with zero carbons attached to the ionized carbon, such as methenium, , are usually included in the primary class).
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Clerodane diterpenes, sometimes referred to as clerodane diterpenoids, are a large group of secondary metabolites that have been isolated from several hundreds of different plant species, as well as fungi, bacteria and marine sponges. They are bicyclic terpenes that contain 20 carbons and a decalin core.
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It is the β-nicotinamide diastereomer of NAD that is found in organisms. These nucleotides are joined together by a bridge of two phosphate groups through the 5' carbons. The redox reactions of nicotinamide adenine dinucleotide. In metabolism, the compound accepts or donates electrons in redox reactions.
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It is a measure of the activated carbon's resistance to attrition. It is an important indicator of activated carbon to maintain its physical integrity and withstand frictional forces. There are large differences in the hardness of activated carbons, depending on the raw material and activity levels.
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Silicynes are allotropes of silicon. 1-dimensional silicyne is analogous to the carbon allotrope carbyne, being a long chain of silicons, instead of carbons. It is amorphous silicon with sp hybridization of the valence electrons. ; ; ; Silicyne is a single linear molecule composed of just silicon atoms.
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Bao X, Focke M, Pollard M, Ohlrogge J. 2000. Understanding in vivo carbon precursor supply for fatty acid synthesis in leaf tissue. Plant Journal 22, 39–50. The typical length of fatty acids produced in the plastid are 16 or 18 carbons, with 0-3 cis double bonds.
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The immediate products of one turn of the Calvin cycle are 2 glyceraldehyde-3-phosphate (G3P) molecules, 3 ADP, and 2 NADP+. (ADP and NADP+ are not really "products." They are regenerated and later used again in the Light-dependent reactions). Each G3P molecule is composed of 3 carbons.
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Curcumin, a linear diarylheptanoid. The diarylheptanoids (also known as diphenylheptanoids) are a relatively small class of plant secondary metabolites. Diarylheptanoids consist of two aromatic rings (aryl groups) joined by a seven carbons chain (heptane) and having various substituents. They can be classified into linear (curcuminoids) and cyclic diarylheptanoids.
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Eveready Industries India Ltd. (EIIL), formerly Union Carbide India Limited, is the flagship company of the B. M. Khaitan Group. The Eveready brand has been present in India since 1905. EIIL's principal activities are the manufacture and market of batteries, flashlight cases, electrolytic manganese dioxide and arc carbons.
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B: Isoprene, also known as 2-methyl-1,3-butadiene, the precursor to natural rubber. C: 1,3-Butadiene, a precursor to synthetic polymers. D: 1,5-Cyclooctadiene, an unconjugated diene (notice that each double bond is two carbons away from the other). E: Norbornadiene, a strained bicyclic and unconjugated diene.
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Decarbamoylsaxitoxin, abbreviated as dcSTX, is a neurotoxin which is naturally produced in dinoflagellate. DcSTX is one of the many analogues of saxitoxin (STX). Figure 1: the structure of saxitoxin, with numbered carbons. Decarbamoylsaxitoxin is one of the derivatives of saxitoxin, which only has a CH2OH group on carbon 1.
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The SSAP (Sequential Structure Alignment Program) method uses double dynamic programming to produce a structural alignment based on atom-to-atom vectors in structure space. Instead of the alpha carbons typically used in structural alignment, SSAP constructs its vectors from the beta carbons for all residues except glycine, a method which thus takes into account the rotameric state of each residue as well as its location along the backbone. SSAP works by first constructing a series of inter-residue distance vectors between each residue and its nearest non- contiguous neighbors on each protein. A series of matrices are then constructed containing the vector differences between neighbors for each pair of residues for which vectors were constructed.
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Like the pinacol type migration the Grob fragmentation relies on an electron donating group to promote the bond migration and encourage the leaving group to be expelled. In this case the electron donating group can be a pseudo electron donating group which is capable of eliminating and donating an electron pair into the carbon with the breaking bond. Working with two smaller rings can allow for elaboration of two parts of the molecule separately before working with the expanded ring. The Dowd-Beckwith ring expansion is also capable of adding several carbons to a ring at a time,e of adding several carbons to a ring at a time, and is a useful tool for making large rings.
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In trans-cycloheptene, however, the size of the ring makes it impossible for the alkene and its two attached carbons to have this geometry because the remaining three carbons could not reach far enough to close the ring (see also Bredt's rule). There would have to be unusually large angles (angle strain), unusually long bond-lengths, or the atoms of the alkane-like loop would collide with the alkene part (steric strain). Part of the strain is relieved by pyramidalization of each alkene carbon and their rotation relative to each other. The pyramidalization angle is estimated at 37° (compared to an angle of 0° for an atom with normal trigonal–planar geometry) and the p-orbital misalignment is 30.1°.
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Sucrose is a disaccharide formed from condensation of glucose and fructose to produce α-D-glucopyranosyl-(1→2)-β-D-fructofuranoside. Sucrose has 8 hydroxyl groups which can be reacted with fatty acid esters to produce sucrose esters. Among the 8 hydroxyl groups on sucrose, three (C6, C1', and C6') are primary while the others (C2, C3, C4, C3', and C4') are secondary. (The numbers 1-6 indicate the position of the carbons on glucose while the numbers 1'-6' indicate the position of the carbons on fructose.) The three primary hydroxyl groups are more reactive due to lower steric hindrance, so they react with fatty acids first, resulting in a sucrose mono-, di-, or triester.
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The sequential structure alignment program (SSAP) method uses double dynamic programming to produce a structural alignment based on atom-to-atom vectors in structure space. Instead of the alpha carbons typically used in structural alignment, SSAP constructs its vectors from the beta carbons for all residues except glycine, a method which thus takes into account the rotameric state of each residue as well as its location along the backbone. SSAP works by first constructing a series of inter-residue distance vectors between each residue and its nearest non-contiguous neighbors on each protein. A series of matrices are then constructed containing the vector differences between neighbors for each pair of residues for which vectors were constructed.
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The most common method for producing porous carbide- derived carbons involves high-temperature etching with halogens, most commonly chlorine gas. The following generic equation describes the reaction of a metal carbide with chlorine gas (M: Si, Ti, V; similar equations can be written for other CDC precursors): :MC (solid) + 2 Cl2 (gas) → MCl4(gas) + C (solid) Halogen treatment at temperatures between 200 and 1000 °C has been shown to yield mostly disordered porous carbons with a porosity between 50 and ~80 vol% depending on the precursor. Temperatures above 1000 °C result in predominantly graphitic carbon and an observed shrinkage of the material due to graphitization. Different bulk porosity of CDCs derived from different carbide precursors.
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A fully carbocyclic spiro compound. Spiropentadiene, an esoteric hydrocarbon, in a representation where all carbons and hydrogens are shown explicitly. The two cyclopropene rings are each planar, but are perpendicular to each other. Spiro compounds may be fully carbocyclic (all carbon) or heterocyclic (having one or more non-carbon atom).
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Heterofullerenes have heteroatoms substituting carbons in cage or tube-shaped structures. They were discovered in 1993 and greatly expand the overall fullerene class of compounds. Notable examples include boron, nitrogen (azafullerene), oxygen, and phosphorus derivatives. Trimetasphere carbon nanomaterials were discovered by researchers at Virginia Tech and licensed exclusively to Luna Innovations.
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To elongate the appendage by 2 carbons, acetyl-CoA is added to the aldehyde in an aldol reaction to afford prestrychnine. Strychnine is then formed by a facile addition of the amine with the carboxylic acid or its activated CoA thioester, followed by ring-closure via displacement of an activated alcohol.
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5 January 2018. For example, membrane lipids left behind by degraded cells will be concentrated, have a limited size range, and comprise an even number of carbons. Similarly, life only uses left-handed amino acids. Biosignatures need not be chemical, however, and can also be suggested by a distinctive magnetic biosignature.
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In the propellanes with small cycles, such as [1.1.1]propellane or [2.2.2]propellane, the two carbons at the ends of the axial bond will be highly strained, and their bonds may even assume an inverted tetrahedral geometry. The resulting steric strain causes such compounds to be unstable and highly reactive.
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However, these clusters later were identified as fullerenes. In 1991, carbyne was allegedly detected among various other allotropes of carbon in samples of amorphous carbon black vaporized and quenched by shock waves produced by shaped explosive charges. In 1995, the preparation of carbyne chains with over 300 carbons was reported.
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A strategy used by pathogens to overcome immune response is the production of siderophores that will not be recognized by siderocalin. For example, siderocalin cannot recognize the siderophores of the C-glucosylated analog of enterobactin, as the donor groups are glycosylated, introducing steric interactions at the position 5-carbons of the catechol groups.
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Imidazolonepropionase catalyzes the reaction to form formiminoglutamate (FIGLU) from 4-imidazolone-5-propionate. The formimino group is transferred to tetrahydrofolate, and the remaining five carbons form glutamate. Overall, these reactions result in the formation of glutamate and ammonia. Glutamate can then be deaminated by glutamate dehydrogenase or transaminated to form α-ketoglutarate.
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Another application lies in metal-free catalysis: 2-mercaptopyridine can be used as a catalyst for isodesmic C-H borylation of heteroarenes. The particular pattern of Lewis base and Brønsted acid allows to cleave boron-carbons bonds and then form a new boron-carbon bond by lewis pair mediated C-H activation.
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The absolute stereochemistry at these carbons is responsible for vincristine's anticancer activity. The liposome encapsulation of vincristine enhances the efficacy of the vincristine drug while simultaneously decreasing the neurotoxicity associated with it. Liposome encapsulation increases vincristine's plasma concentration and circulation lifetime in the body, and allows the drug to enter cells more easily.
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Elaidic acid has 18 carbons and is a trans-9-mono-unsaturated fatty acid. It is also a trans isomer of oleic acid. C17H33CO2H, IUPAC organization name (E)-octadec-9-enoic acid, numerical representation 18:1 (9), n-9, molecular weight 282.46, melting point 43-45 °C. CAS Registry Number 112-79-8.
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Hydrogenated jojoba oil is a straight- chain wax ester of 36 to 46 carbons in length, an ester bond in the approximate middle of the chain, no branching, no points of unsaturation, and terminal methyl groups at each end. As with jojoba oil, there is no triglyceride component of hydrogenated jojoba oil.
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Diamond and Related Materials is a peer-reviewed scientific journal in materials science covering research on all forms of diamond and other related materials, including diamond-like carbons, carbon nanotubes, graphene, and boron and carbon nitrides. The journal is published by Elsevier and the editor-in-chief is Ken Haenen (University of Hasselt).
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Carbohydrates with more than 4 carbons exist in an equibrium between the closed ring, or cyclic form, and the open-chain form. Cyclic aldoses are usually drawn as Haworth projections, and open chain forms are commonly drawn as Fischer projections, both of which represent important stereochemical information about the forms they depict.
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Norbornene or norbornylene or norcamphene is a highly strained bridged cyclic hydrocarbon. It is a white solid with a pungent sour odor. The molecule consists of a cyclohexene ring with a methylene bridge between carbons 1 and 4. The molecule carries a double bond which induces significant ring strain and significant reactivity.
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Hxd3 is a delta-proteobacterium capable of utilizing C12-C20 alkanes as growth substrates. Hxd3 activates alkanes via carboxylation at C3, with subsequent elimination of the terminal and subterminal carbons, yielding a fatty acid that is one carbon shorter than the parent alkane.So, C. M., C. D. Phelps, and L. Y. Young. 2003.
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Similar to how image recognition networks learn to compose smaller, spatially proximate features into larger, complex structures, AtomNet discovers chemical features, such as aromaticity, sp3 carbons and hydrogen bonding. Subsequently, AtomNet was used to predict novel candidate biomolecules for multiple disease targets, most notably treatments for the Ebola virus and multiple sclerosis.
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Pyruvate dehydrogenase complex reaction Pyruvate decarboxylation or pyruvate oxidation, also known as the link reaction, is the conversion of pyruvate into acetyl-CoA by the enzyme complex pyruvate dehydrogenase complex. The reaction may be simplified as: 1 Pyruvate + 1 NAD+ \+ CoA → 1 Acetyl-CoA + NADH + CO2 \+ H+ Pyruvate oxidation is the step that connects glycolysis and the Krebs cycle. In glycolysis, a single glucose molecule (6 carbons) is split into 2 pyruvates (3 carbons each), hence link reaction occurs twice for each glucose molecule to produce a total of 2 acetyl-CoA molecules, which can then enter the Krebs cycle. Energy-generating ions and molecules such as amino acids and carbohydrates enter the Krebs cycle as acetyl coenzyme A and oxidize in the cycle.
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Alternatively, the label "ω−x" is written "n−x", where the "n" is meant to represent the number of carbons in the chain.A common mistake is to say that the last carbon is "ω−1". Another common mistake is to say that the position of a bond in omega-notation is the number of the carbon closest to the END. For double bonds, these two mistakes happen to compensate each other; so that a "ω−3" fatty acid indeed has the double bond between the 3rd and 4th carbons from the end, counting the methyl as 1. However, for substitutions and other purposes, they don't: a hydroxyl "at ω−3" is on carbon 15 (4th from the end), not 16.
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Like most monosaccharides with five or more carbons, each aldohexose or 2-ketohexose also exists in one or more cyclic (closed-chain) forms, derived from the open-chain form by an internal rearrangement between the carbonyl group and one of the hydroxyl groups. The reaction turns the =O group into an hydroxyl, and the hydroxyl into an ether bridge (–O–) between the two carbon atoms, thus creating a ring with one oxygen atom and four or five carbons. If the cycle has five carbon atoms (six atoms in total), the closed form is called a pyranose, after the cyclic ether tetrahydropyran, that has the same ring. If the cycle has four carbon atoms (five in total), the form is called furanose after the compound tetrahydrofuran.
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Diels–Alder reactions, as concerted cycloadditions, are stereospecific. Stereochemical information of the diene and the dienophile are retained in the product, as a syn addition with respect to each component. For example, substituents in a cis (trans, resp.) relationship on the double bond of the dienophile give rise to substituents that are cis (trans, resp.) on those same carbons with respect to the cyclohexene ring. Likewise, cis,cis- and trans,trans-disubstitued dienes give cis substituents at these carbons of the product whereas cis,trans- disubstituted dienes give trans substituents: 500x500pxEndo and exo transition states for cyclopentadiene adding to thumb Diels–Alder reactions in which adjacent stereocenters are generated at the two ends of the newly-formed single bonds imply two different possible stereochemical outcomes.
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Naturally occurring diamond is almost always found in the crystalline form with a purely cubic orientation of sp3 bonded carbon atoms. Sometimes there are lattice defects or inclusions of atoms of other elements that give color to the stone, but the lattice arrangement of the carbons remains cubic and bonding is purely sp3. The internal energy of the cubic polytype is slightly lower than that of the hexagonal form and growth rates from molten material in both natural and bulk synthetic diamond production methods are slow enough that the lattice structure has time to grow in the lowest energy (cubic) form that is possible for sp3 bonding of carbon atoms. In contrast, DLC is typically produced by processes in which high energy precursive carbons (e.g.
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Nylon 66 can have multiple parallel strands aligned with their neighboring peptide bonds at coordinated separations of exactly 6 and 4 carbons for considerable lengths, so the carbonyl oxygens and amide hydrogens can line up to form interchain hydrogen bonds repeatedly, without interruption (see the figure opposite). Nylon 510 can have coordinated runs of 5 and 8 carbons. Thus parallel (but not antiparallel) strands can participate in extended, unbroken, multi-chain β-pleated sheets, a strong and tough supermolecular structure similar to that found in natural silk fibroin and the β-keratins in feathers. (Proteins have only an amino acid α-carbon separating sequential -CO-NH- groups.) Nylon 6 will form uninterrupted H-bonded sheets with mixed directionalities, but the β-sheet wrinkling is somewhat different.
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Among the precursors for hard carbon are polyvinylidene chloride (PVDC), lignin and sucrose. Other precursors, such as polyvinyl chloride (PVC) and petroleum coke, produce soft carbon, or graphitizing carbon. Soft carbon can be readily converted to graphite by heating to 3000°C. The physical properties of the two classes of carbons are quite different.
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The unusual tert-butyl substituent is formed from A ring cleavage in 9. Bilobalide 13 then formed in loss of carbons through degradation from ginkgolide 12, and lactones are formed from residual carboxyl and alcohol functions. The end product of bilobalide contains sesquiterpenes and three lactones units.Dewick, P. M. Medicinal Natural Products: Products:A Biosynthetic Approach.
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5-Nonanone was expected to be metabolized to a γ-diketone (a diketone with the second oxygen three carbons away from the first, e.g. 2,5- or 3,6-diketones). Metabolic studies confirmed the in vivo ω-oxidation of 5-nonanone to 2,5-nonanedione and 2-hexanone. Subsequent oxidative and decarboxylative steps also produce 2,5-hexanedione.
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The Varrentrapp reaction, also named Varrentrapp degradation, is a name reaction in the organic chemistry. It is named after Franz Varrentrapp, who described this reaction in 1840.F. Varrentrapp, Ann., 36, 196 (1840) The reaction entails the degradation of an unsaturated carboxylic acid into acetic acid and a second acid, shortened by two carbons.
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Heterotrophs consume the glucose, which further breaks down the compounds and passes them through webs (this process is called cellular respiration). Living systems and decomposers release the carbons as carbon dioxide. This carbon is cycled quickly, with estimates of 1,000 to 1000,000 million metric tons of carbon cycling through these pathways in a single year.
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Similarly, b indicates one carbon and c indicates two carbons. While indenofluorenes are members of the polycyclic hydrocarbon family, they are not necessarily members of the polycyclic aromatic hydrocarbon family. For example, the fully conjugated versions, shown below, have 20π electrons making them formally anti-aromatic. First indenofluorene scaffold synthesized by Dr. Gabriel in 1884.
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Medium-sized rings (7–13 carbons) experience more strain energy than cyclohexane, due mostly to deviation from ideal vicinal angles, or Pitzer strain. Molecular machanics calculations indicate that transannular strain, also known as Prelog strain, does not play an essential role. Transannular reactions however, such as 1,5-shifts in cyclooctane substitution reactions, are well known.
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Variety Hall ( Delite Theatre) Coimbatore During 1905, electric carbons were used in motion picture projector. During the same year Samikannu Vincent established his first tent cinema at Madras called Edison's Grand Cinemamegaphone on Esplanade. At that time it was a novelty to watch films in this tent theatre. The electrically lit tent drew large crowds.
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For example, glycine with two carbons is converted to acetate. In this way, amino acid fermenting microbes can avoid using hydrogen ions as electron acceptors to produce hydrogen gas. Amino acids can be Stickland acceptors, Stickland donors, or act as both donor and acceptor. Only histidine cannot be fermented by Stickland reactions, and is oxidised.
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Some carbons are evaluated based on the dechlorination half-life length, which measures the chlorine-removal efficiency of activated carbon. The dechlorination half-value length is the depth of carbon required to reduce the chlorine level of a flowing stream from 5 ppm to 3.5 ppm. A lower half-value length indicates superior performance.
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This compound is unstable (although not as much as [1.1.1]propellane; however it is less persistent than [1.1.1]propellane). The bond angles on the shared carbons are considerably strained: three of them are close to 90°, the other three to 120°. The strain energy is estimated to be 93 kcal/mol (390 kJ/mol).
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Cyclodecane in its lowest energy conformation. The red triangle indicates three hydrogens responsible for transannular strain. There is an identical interaction on the back of the molecule, as well. In organic chemistry, transannular strain (also called Prelog strain after Nobel Prize–winning chemist Vladimir Prelog) is the unfavorable interactions of ring substituents on non-adjacent carbons.
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Magnetic inequivalence can lead to highly complex spectra which can only be analyzed by computational modeling. Such effects are more common in NMR spectra of aromatic and other non-flexible systems, while conformational averaging about C−C bonds in flexible molecules tends to equalize the couplings between protons on adjacent carbons, reducing problems with magnetic inequivalence.
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D mode is present in all graphite-like carbons and originates from structural defects. Therefore, the ratio of the G/D modes is conventionally used to quantify the structural quality of carbon nanotubes. High-quality nanotubes have this ratio significantly higher than 100. At a lower functionalisation of the nanotube, the G/D ratio remains almost unchanged.
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Fumigation and nematicides are used to reduced initial population densities. Halogenated hydro-carbons ( MBr,1-3-D and chloropicin) are the most effective.Sorribas, F.J. Verdejo-Lucas, M. Galeano, J. Pastor, and C.Ornat. 2003. Effect of 1,3-dichloropropene and rootstocks alone and in combination on Tylenchulus semipenetrans and citrus tree growth in a replant managenement program. Nematropica.
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The mechanism of the Pratt diene rearranging; note the regioselectivity 550px The barrelene rearrangement is now presented. It is a bit more complex than the Mariano and Pratt examples since there are two sp3-hybridized (i.e. methane) carbons. Each such bridgehead carbon has three (ethylenic) pi bonds while two are needed for the di-pi-methane rearrangement.
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P450scc catalyzes the conversion of cholesterol to pregnenolone in three monooxygenase reactions. These involve 2 hydroxylations of the cholesterol side-chain, which generate, first, 22R-hydroxycholesterol and then 20alpha,22R-dihydroxycholesterol. The final step cleaves the bond between carbons 20 and 22, resulting in the production of pregnenolone and isocaproic aldehyde. Each monooxygenase step requires 2 electrons (reducing equivalents).
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Oxidative breakage of carbon-carbon bond in 1,2-diols Alcohols possessing two hydroxy groups located on adjacent carbons —that is, 1,2-diols— suffer oxidative breakage at a carbon-carbon bond with some oxidants such as sodium periodate (NaIO4) or lead tetraacetate (Pb(OAc)4), resulting in generation of two carbonyl groups. The reaction is also known as glycol cleavage.
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A primary or secondary aliphatic amine separated by 2 carbons from a substituted benzene ring is minimally required for high agonist activity. The pKa of the amine is approximately 8.5-10.Medicinal Chemistry of Adrenergics and Cholinergics The presence of hydroxy group in the benzene ring at 3rd and 4th position shows maximum alpha- and beta-adrenergic activity.
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Dihydroxyacetone phosphate lies in the glycolysis metabolic pathway, and is one of the two products of breakdown of fructose 1,6-bisphosphate, along with glyceraldehyde 3-phosphate. It is rapidly and reversibly isomerised to glyceraldehyde 3-phosphate. The numbering of the carbon atoms indicates the fate of the carbons according to their position in fructose 6-phosphate.
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In general, volatility tends to decrease with increasing molecular mass, although other factors such as structure and polarity play a significant role. The effect of molecular mass can be partially isolated by comparing chemicals of similar structure (i.e. esters, alkanes, etc.). For instance, linear alkanes exhibit decreasing volatility as the number of carbons in the chain increases.
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Ethynol, the simplest ynol In chemistry, an ynol (or alkynol) is an alkyne with a hydroxyl group affixed to one of the two carbons composing the triple bond. The deprotonated anions of ynols are known as ynolates. An ynol with hydroxyl groups on both sides of its triple bond is known as an ynediol; only one ynediol, acetylenediol, exists.
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Glucose molecule, showing carbon numbering notation and beta orientation. In mixed linkage glucan bonds form only on carbons 1, 3 and 4. MLG is composed of β-D(1-3) and β-D(1-4)-linked glucosyl residues. Typically there are regions of 2-5 β-D(1-4)-linked residues separated by β-D(1-3)-linkages.
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The molecular structure of uroporphyrinogen III can be described as a hexahydroporphine core, where each pyrrole ring has the hydrogen atoms on its two outermost carbons replaced by an acetic acid group (, "A") and a propionic acid group (, "P"). The groups are attached in an asymmetric way: going around the macrocycle, the order is AP-AP-AP-PA.
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Heteroatom-promoted lateral lithiation is the site-selective replacement of a benzylic hydrogen atom for lithium for the purpose of further functionalization. Heteroatom-containing substituents may direct metalation to the benzylic site closest to the heteroatom or increase the acidity of the ring carbons via an inductive effect.Clark, R. D.; Jahangir, A. Org. React. 1995, 47, 1.
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There are several conventions for naming IFs currently in use. The preferred version uses a [1,2] or [2,1] to describe if the orientation of the methylene bridges on the 5 member rings are anti ([1,2]) or syn ([2,1]). The a, b, c designation indicates connectivity. a indicates there are no carbons between the indene and the starred fluorene carbon.
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Carbons 4 and 5 also have a double bond, represented by 'Δ4,5'. The reaction involves a stereospecific and permanent break of the Δ4,5 with the help of NADPH as a cofactor. A hydride anion (H−) is also placed on the α face at the fifth carbon, and a proton on the β face at carbon 4.
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Hemmings once had an enormous bakery building on land just north of Chadwell Heath station. This building was derelict by the 1970s and was later demolished for housing. For many years Bergermaster Paints maintained a large factory in Freshwater Road. Grove Road was also an industrial area with Wiggins Teape and Morganite Carbons Ltd among companies based there.
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Dragan and his colleague were the first to report about isomerization in alkanes. Isomerization and reformation are processes in which straight-chain alkanes are heated in the presence of a platinum catalyst. In isomerization, the alkanes become branched-chain isomers. In other words, it does not lose any carbons or hydrogens, keeping the same molecular weight.
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Ergosterol is a smaller molecule than lanosterol; it is synthesized by combining two molecules of farnesyl pyrophosphate, a 15-carbon- long terpenoid, into lanosterol, which has 30 carbons. Then, two methyl groups are removed, making ergosterol. The "azole" class of antifungal agents inhibit the enzyme that performs these demethylation steps in the biosynthetic pathway between lanosterol and ergosterol.
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The HERA project also conducted an environmental review of alkyl sulfates that found all alkyl sulfates are readily biodegradable and standard wastewater treatment operations removed 96–99.96% of short-chain (12–14 carbons) alkyl sulfates. Even in anaerobic conditions at least 80% of the original volume is biodegraded after 15 days with 90% degradation after 4 weeks.
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Hypochlorous acid reacts with unsaturated bonds in lipids, but not saturated bonds, and the ClO− ion does not participate in this reaction. This reaction occurs by hydrolysis with addition of chlorine to one of the carbons and a hydroxyl to the other. The resulting compound is a chlorohydrin. The polar chlorine disrupts lipid bilayers and could increase permeability.
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Other techniques focus on the activation of the desired carbon rather than blocking undesired carbons. A carbon may be activated by a halogen. A C-X bond (X = halide) is more favorable for activation than a C-H bond. This pathway results in the oxidative addition of the MIC carbene halide to a low valent metal center.
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Asymmetrical tropocoronands where the number of carbons of the simple straight-chain linkages is different (m ≠ n, but variability in the m,n lengths tends to be only by 1 methylene group)Jaynes, B.S.; Doerrer, L.H.; Liu, S.; Lippard, S.J. Inorg. Chem. 1995 , 34, 5735-5744.Jaynes, B.S.; Ren, T.; Masschelwin, A.; Lippard, S.J. J. Am. Chem. Soc.
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The solid or skeletal density of activated carbons will typically range between 2000 and 2100 kg/m3 (125–130 lbs./cubic foot). However, a large part of an activated carbon sample will consist of air space between particles, and the actual or apparent density will therefore be lower, typically 400 to 500 kg/m3 (25–31 lbs./cubic foot).
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In organic chemistry, a diazapentalene is any of the heterocyclic compounds having molecular formula C6H6N2 whose structure is two fused two pentagonal rings of six carbon atoms and two nitrogen atoms. That is, it is a heteropentalene, with two nitrogens substituted in for carbons. There are several different constitutional isomers. Each diazapentalene has 10 pi electrons and shows aromaticity.
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The molecular orbital explanation of the stability of homoaromaticity has been widely discussed with numerous diverse theories, mostly focused on the homotropenylium cation as a reference. R.C. Haddon initially proposed a Mobius model where the outer electrons of the sp3 hybridized methylene bridge carbon(2) back-donate to the adjacent carbons to stabilize the C1-C3 distance.
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The authors mark the biosynthetic origin as mysterious Scheme 5. Haouamine A In this compound the deviation from planarity is 13° for the benzene ring and 17° for the bridgehead carbons. An alternative cyclophane formation strategy in scheme 6Scheme 6. Reaction scheme: step I elimination reaction of methanol with trifluoroethanol and diisopropylamine, step II methylation with dimethyl sulfate.
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Hydrogen storage in nanostructured carbons by spillover: bridge-building enhancement. Langmuir : the Acs Journal of Surfaces and Colloids, 21, 24, 11418-24. Current trends include the use of metal-organic frameworks (MOFs) and other porous materials with high surface area for such storage, including but not exclusive to nanocarbons (e.g. graphene, carbon nanotubes), zeolites, and nanostructured materials.
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Norhopanes are a family of demethylated hopanes, identical to the methylated hopane structure, minus indicated desmethylated carbons. 28,30-bisnorhopane, the more common bisnorhopane biomarker, indicates the absence of methyl groups from C28 and C30, while 25,28,30-trisnorhopane, a related compound often found in concurrence with 28,30-bisnorhopane, indicates three demethylated zones across C25, C28, and C30.
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Peptide amphiphiles (PAs) are peptide-based molecules that self-assemble into supramolecular nanostructures including; spherical micelles, twisted ribbons, and high-aspect-ratio nanofibers. A peptide amphiphile typically comprises a hydrophilic peptide sequence attached to a lipid tail, i.e. a hydrophobic alkyl chain with 10 to 16 carbons. Therefore, they can be considered a type of lipopeptide.
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Aprepitant is made up of a morpholine core with two substituents attached to adjacent ring carbons. These substitute groups are trifluoromethylated 1-phenylethanol and fluorophenyl group. Aprepitant also has a third substituent (triazolinone), which is joined to the morpholine ring nitrogen. It has three chiral centres very close together, which combine to produce an amino acetal arrangement.
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The notation Δx,y,... is traditionally used to specify a fatty acid with double bonds at positions x,y,.... (The capital Greek letter "Δ" (delta) corresponds to Roman "D", for Double bond). Thus, for example, the 20-carbon arachidonic acid is Δ5,8,11,14, meaning that it has double bonds between carbons 5 and 6, 8 and 9, 11 and 12, and 14 and 15. In the context of human diet and fat metabolism, unsaturated fatty acids are often classified the position of the double bond closest to the ω carbon (only), even in the case of multiple double bonds such as the essential fatty acids. Thus arachidonic acid, linoleic acid (18 carbons, Δ9,12), and myristoleic acid (14-carbon, Δ8) are all classified as "ω−3" fatty acids; meaning that their formula ends with –CH=CH––.
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40% of the carbon dioxide produced via decomposition has been observed to be radioactive, suggesting that the non-classical picture is more correct. Further distinction between non-classical and classical structures of the 2-norbornyl cation is possible by combining NMR experiments with isotope- labeling experiments. Isotopic substitution of one of two deuterium atoms for a hydrogen atom causes the environment of nearby NMR-active atoms to change dramatically. Asymmetric deuterium isotope labeling (substitution) will cause a set of carbons that were all equivalent in the all-hydrogen species to be split into two or more sets of equivalent carbons in the deutero-labeled species; this will be manifested in the NMR spectrum as one peak in the all- hydrogen species' spectrum becoming at least two "split" peaks in the deutero- labeled species.
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Agaric acid is a type of fatty acid that is composed by a long hydrocarbon chain ("tail") and three carboxylic acid groups at one end ("head"). The hydrocarbon chain has sixteen carbons and thirty four hydrogens. This acid has microcrystalline properties, and therefore, forms small crystals that can not be seen through the naked eye, but are only visible with an optical microscope.
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These carbons were used for arc lighting, the principle electric light at the time. Willis U. Masters soon retired due to poor health. Lawrence brought in a group of investors including Myron T. Herrick, James Parmelee and Webb Hayes. In 1886, under the leadership of Washington Lawrence, the new management team at Boulton Carbon immediately went to work on two items.
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The "ene" ending was chosen to indicate that the carbons are unsaturated, being connected to only three other atoms instead of the normal four. The shortened named "fullerene" eventually came to be applied to the whole family. Kroto, Curl, and Smalley were awarded the 1996 Nobel Prize in Chemistry for their roles in the discovery of this class of molecules.
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CRC Press. Metabolism of propionate begins with its conversion to propionyl coenzyme A (propionyl-CoA), the usual first step in the metabolism of carboxylic acids. Since propanoic acid has three carbons, propionyl-CoA can directly enter neither beta oxidation nor the citric acid cycles. In most vertebrates, propionyl-CoA is carboxylated to D-methylmalonyl-CoA, which is isomerised to L-methylmalonyl-CoA.
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Bile acyl-CoA synthetase is an enzyme that in humans is encoded by the SLC27A5 gene. The protein encoded by this gene is an isozyme of very long-chain acyl- CoA synthetase (VLCS). It is capable of activating very long-chain fatty-acids containing 24- and 26-carbons. It is expressed in liver and associated with endoplasmic reticulum but not with peroxisomes.
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In the optimized structure of borole shown to the left, the B1C, 1C2C, and 2C2C bond lengths are approximately 1.58, 1.338, and 1.518 Å respectively, as shown to the left. The longer 2C2C bond in C4H4BH agree with NBO analysis that the π-electron delocalizations are mainly confined on the methine carbons, supporting the antiaromatic nature of the neutral borole.
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When the single bond between the two centres is free to rotate, cis/trans descriptors become invalid. Two widely accepted prefixes used to distinguish diastereomers on sp³-hybridised bonds in an open-chain molecule are syn and anti. Masamune proposed the descriptors which work even if the groups are not on adjacent carbons. It also works regardless of CIP priorities.
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An example where charge shift bonding has been used to explain the low electron density found experimentally is in the central bond between the inverted tetrahedral carbons in [1.1.1]propellanes. Theoretical calculations on a range of molecules have indicated that a charge shift bond is present, a striking example being fluorine, F2, which is normally described as having a typical covalent bond.
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The inverse vulcanization process can also be employed for the synthesis of activated carbon with narrow pore-size distributions. The sulfur-rich copolymer acts here as a template where the carbons are produced. The final material is doped with sulfur and exhibits a micro-porous network and high gas selectivity. Therefore, inverse vulcanization could be also applied in the gas separation sector.
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Xu5P is converted into RuP by phosphopentose epimerase. # Finally, phosphoribulokinase (another plant-unique enzyme of the pathway) phosphorylates RuP into RuBP, ribulose-1,5-bisphosphate, completing the Calvin cycle. This requires the input of one ATP. Thus, of six G3P produced, five are used to make three RuBP (5C) molecules (totaling 15 carbons), with only one G3P available for subsequent conversion to hexose.
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Photorespiration turns RuBP into 3-PGA and 2-phosphoglycolate, a 2-carbon molecule that can be converted via glycolate and glyoxalate to glycine. Via the glycine cleavage system and tetrahydrofolate, two glycines are converted into serine +. Serine can be converted back to 3-phosphoglycerate. Thus, only 3 of 4 carbons from two phosphoglycolates can be converted back to 3-PGA.
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Oxatriquinacene is an organic cation with formula . It is an oxonium ion, with a trivalent oxygen atom with +1 charge connected to carbons 1,4, and 7 of a cyclononatriene ring, forming three fused pentagonal cycles. The compound may possess weak tris-homoaromatic character. Oxatriquinacene has remarkable stability compared to other oxonium cations, although not as extreme as that of the similar oxatriquinane.
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The lithium atoms and the ipso carbons of the phenyl rings form a planar four-membered ring. The plane of the phenyl groups are perpendicular to the plane of this Li2C2 ring. Additional strong intermolecular bonding occurs between these phenyllithium dimers and the π electrons of the phenyl groups in the adjacent dimers, resulting in an infinite polymeric ladder structure.
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Benzene Benzene, C6H6, is the least complex aromatic hydrocarbon, and it was the first one named as such. The nature of its bonding was first recognized by August Kekulé in the 19th century. Each carbon atom in the hexagonal cycle has four electrons to share. One goes to the hydrogen atom, and one to each of the two neighbouring carbons.
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Because of the Nikwax technologies employed none of the cleaning or treatment products used to produce or maintain Páramo products are environmentally persistent or toxic. Páramo does not use any fluro-carbons, either as a DWR treatment or as a waterproof barrier. Páramo also works with The World Land Trust on conservation efforts and carbon offsetting of all aspects of its operations.
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The structural formula of prymnesin-2 is: C96H136Cl3NO35. The compound has two chiral centers, at the carbon atoms C14 and C85. The molecule is amphoteric, which means that it can act both as base and an acid. This is because all 16 hydroxyls, except for one at C32, are concentrated on carbons C48-84, and there is a xylose moiety at C77.
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The protein NMR structure of maurotoxin, illustrating the fluctuations in the protein's native state in solution. The protein backbone is shown in red, the alpha carbons of the eight cysteine residues in green, and the disulfide bridges in yellow. Compare the disulfide bond connectivity to HsTx1 below. The protein NMR structure of HsTx1, a scorpion toxin with a canonical disulfide bond connectivity.
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The resulting helix is chiral. For helicenes with six benzene units, a 360° turn is completed. In the helicene series the dihedral angles between the extremities increases going from [4]helicene (26°) to [6]helicene (58°) and then decreases again for example in [7]helicene (30°). Helicenes are notable for having chirality despite lacking both asymmetric carbons and chiral centers.
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The convention for a nucleic acid sequence is to list the nucleotides as they occur from the 5' end to the 3' end of the polymer chain, where 5' and 3' refer to the numbering of carbons around the ribose ring which participate in forming the phosphate diester linkages of the chain. Such a sequence is called the primary structure of the biopolymer.
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Additionally, it is considered a probable degradation product of many other compounds. PFNA is the largest perfluorinated carboxylic acid surfactant. Fluorocarbon derivatives with terminal carboxylates are only surfactants when they possess five to nine carbons. Fluorosurfactants reduce the surface tension of water down to half of what hydrocarbon surfactants can by concentrating at the liquid-air interface due to the lipophobicity of fluorocarbons.
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2001, 123, 11863–11869. center Notably, a ring expansion is observed for enynes with cyclic alkene motifs. This is rationalized by a formal insertion of the methylene group of the olefin between the two carbons of the alkyne; a mechanistic reasoning for this ring expansion has also been proposed.Zhang, L.; Sun, J.; Kozmin, S. A. Adv. Synth. Catal. 2006, 348, 2271–2296.
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Anecortave can be synthesized from a 17-oxosteroid: 500px In addition to being synthesized from a 17-oxosteroid, anecortave acetate can be derived from cortisol by reducing the 11-beta hydroxyl on cortisol to a double bond between carbons 9 and 11 and the addition of an acetate group to carbon 21. This results in a molecule with no glucocorticoid or mineralocorticoid activity.
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In systematic chemical nomenclature, alkynes are named with the Greek prefix system without any additional letters. Examples include ethyne or octyne. In parent chains with four or more carbons, it is necessary to say where the triple bond is located. For octyne, one can either write 3-octyne or oct-3-yne when the bond starts at the third carbon.
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Methedrone is a synthetic cathinone. It is related to the parent compound cathinone. Methedrone belongs to the phenethylamine family due to the presence of the cyclic group of atoms C6H5 in which six carbons bind to form a hexagonal ring with five hydrogens each bonding to a carbon and the remaining carbon bonded to an atom or group of atoms other than hydrogen.
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With the formula Zn[(S2P(OR)2]2, zinc dithiophosphate features diverse R groups. Typically, R is a branched or linear alkyl between 1-14 carbons in length. Examples include 2-butyl, pentyl, hexyl, 1,3-dimethylbutyl, heptyl, octyl, isooctyl (2-ethylhexyl), 6-methylheptyl, 1-methylpropyl, dodecylphenyl, and others. A mix of zinc dialkyl(C3-C6)dithiophosphates come under CAS number .
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The two histidine residues provide the fifth and sixth heme ligands, and the propionate edge of the heme group lies at the opening of the heme crevice. Two isomers of cytochrome b5, referred to as the A (major) and B (minor) forms, differ by a 180° rotation of the heme about an axis defined by the α- and γ-meso carbons.
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Perfluorinated oxaziridines are known to hydroxylate unactivated hydrocarbons with remarkable regio- and diastereospecificity. This is a highly coveted transformation, and similar reactivity and specificity is seldom rivaled, especially considering the nonmetallic nature of the oxidant. Perfluorinated oxaziridines show high selectivity toward tertiary hydrogens. Hydroxylation of primary carbons and dihydroxylation of a compound with two oxidizable sites have never been observed.
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The methylglyoxal molecule consists of two carbonyl groups flanked by a hydrogen atom and a methyl group. In the discussion below, these two carbonyl carbons will be denoted as C1 and C2, respectively. In both the hemithioacetal substrate and the (R)-S-lactoylglutathione product, the glutathione moiety is bonded to the C1 carbonyl group. The basic mechanism of glyoxalase I is as follows.
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The C-M bond is typically found to be around 1.65 angstroms. The 13CNMR resonance values for the carbido carbons vary widely, but range from δ211-406. An early example of a terminal carbido complex is Li[MoC(NR2)3], which was prepared by deprotonation of the methylidyne precursor. X-ray crystallographic analysis reveals a Mo-C distance of 172 pm.
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A second group of methanogens use methanol () as a substrate for methanogenesis. These are chemoorganotrophic, but still autotrophic in using as only carbon source. The biochemistry of this process is quite different from that of the carbon dioxide-reducing methanogens. Lastly, a third group of methanogens produce both methane and carbon dioxide from acetate () with the acetate being split between the two carbons.
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A fixed bed of porous materials (e.g. activated carbons and zeolites) is pressurized and purged with a carrier gas. After becoming stationary one or more adsorptives are added to the carrier gas, resulting in a step-wise change of the inlet concentration. This is in contrast to chromatographic separation processes, where pulse-wise changes of the inlet concentrations are used.
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Some carbons are more adept at adsorbing large molecules. Molasses number or molasses efficiency is a measure of the mesopore content of the activated carbon (greater than 20 Å, or larger than 2 nm) by adsorption of molasses from solution. A high molasses number indicates a high adsorption of big molecules (range 95–600). Caramel dp (decolorizing performance) is similar to molasses number.
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Similar to other pheromone biosynthesis reactions, female cabbage looper pheromone production initiates with synthesis of 16 and 18-carbon fatty acids. This is followed by desaturation at C1 and chain shortening by two or four carbons. Finally, the fatty acid is reduced and acetylated to form an acetate ester. The result is a blend of different female pheromone compounds at a consistent ratio.
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The carbons alpha to carbonyl groups can be deprotonated by a strong base. The carbanion formed can undergo nucleophilic substitution on the alkyl halide, to give the alkylated compound. On heating, the di-ester undergoes thermal decarboxylation, yielding an acetic acid substituted by the appropriate R group. Thus, the malonic ester can be thought of being equivalent to the −CH2COOH synthon.
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Alkanes generally have minimum energy when the C–C–C angles are close to 110 degrees. Conformations of the cyclohexane molecule with all six carbon atoms on the same plane have a higher energy, because some or all the C–C–C angles must be far from that value (120 degrees for a regular hexagon). Thus the conformations which are local energy minima have the ring twisted in space, according to one of two patterns known as chair (with the carbons alternately above and below their mean plane) and boat (with two opposite carbons above the plane, and the other four below it). If the energy barrier between two conformational isomers is low enough, it may be overcome by the random inputs of thermal energy that the molecule gets from interactions with the environment or from its own vibrations.
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The IUPAC nomenclature (systematic way of naming compounds) for alkanes is based on identifying hydrocarbon chains. Unbranched, saturated hydrocarbon chains are named systematically with a Greek numerical prefix denoting the number of carbons and the suffix "-ane". In 1866, August Wilhelm von Hofmann suggested systematizing nomenclature by using the whole sequence of vowels a, e, i, o and u to create suffixes -ane, -ene, -ine (or -yne), -one, -une, for the hydrocarbons CnH2n+2, CnH2n, CnH2n−2, CnH2n−4, CnH2n−6.Alkane Nomenclature Now, the first three name hydrocarbons with single, double and triple bonds;Thus, the ending "-diene" is applied in some cases where von Hofmann had "-ine" "-one" represents a ketone; "-ol" represents an alcohol or OH group; "-oxy-" means an ether and refers to oxygen between two carbons, so that methoxymethane is the IUPAC name for dimethyl ether.
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A popular choice of working fluid is ammonia, which has superior transport properties, easy availability, and low cost. Ammonia, however, is toxic and flammable. Fluorinated carbons such as CFCs and HCFCs are not toxic or flammable, but they contribute to ozone layer depletion. Hydrocarbons too are good candidates, but they are highly flammable; in addition, this would create competition for use of them directly as fuels.
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New York: John Wiley & Sons, inc. An alkyl group is a piece of a molecule with the general formula CnH2n+1, where n is the integer depicting the number of carbons linked together. For example, a methyl group (n = 1, CH3) is a fragment of a methane molecule (CH4). Alkylating agents use selective alkylation by adding the desired aliphatic carbon chain to the previously chosen starting molecule.
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An example of both is (Cp2Fe(CO)2).. It is probable that η1-Cp complexes are intermediates in the formation of η5-Cp complexes. Still rarer, the Cp unit can bond to the metal via a three-carbons. In these η3-Cp complexes, the bonding resembles that in allyl ligands. Such complexes, sometimes called "slipped Cp complexes", are invoked as intermediates in ring slipping reactions.
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Stearoyl-CoA is a coenzyme involved in the metabolism of fatty acids. Stearoyl-CoA is an 18-carbon long fatty acyl-CoA chain that participates in an unsaturation reaction. The reaction is catalyzed by the enzyme stearoyl-CoA desaturase, which is located in the endoplasmic reticulum. It forms a cis- double bond between the ninth and tenth carbons within the chain to form the product oleoyl-CoA.
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5′ cap structure (cap-2). Ribose structure showing the positions of the 2′, 3′ and 5′ carbons. In eukaryotes, the 5′ cap (cap-0), found on the 5′ end of an mRNA molecule, consists of a guanine nucleotide connected to mRNA via an unusual 5′ to 5′ triphosphate linkage. This guanosine is methylated on the 7 position directly after capping in vivo by a methyltransferase.
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The double bonds are such that the three middle carbons are in a straight line, while the first three and last three lie on perpendicular planes. The molecule and its mirror image are not superimposable, even though the molecule has an axis of symmetry. The two enantiomers can be distinguished, for example, by the right- hand rule. This type of isomerism is called axial isomerism.
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The choice of aryl halide or pseudohalide substrate (sp2-carbon) is one of the factors that mainly influence the reactivity of the Sonogashira catalytic system. The reactivity of halides is higher towards iodine, and vinyl hallides are more reactive than analogous aryl halides. The rate of reaction of sp2 carbons. Vinyl iodide > vinyl triflate > vinyl bromide > vinyl chloride > aryl iodide > aryl triflate > aryl bromide >>> aryl chloride.
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A very-long-chain fatty acid (VLCFA) is a fatty acid with 22 or more carbons. Their biosynthesis occurs in the endoplasmic reticulum.Jakobsson, Andreas; Westerberg, Rolf; Jacobsson, Anders "Fatty acid elongases in mammals: their regulation and roles in metabolism" Progress in Lipid Research 2006, volume 45, pp. 237-249. VLCFA's can represent up to a few percent of the total fatty acid content of a cell.
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The first of its kind was established in Madras, called "Edison's Grand Cinemamegaphone". This was due to the fact that electric carbons were used for motion picture projectors. Full-fledged film studios were built in Salem (Modern Theatres Studio) and Coimbatore (Central Studios, Neptune, and Pakshiraja). Chennai became the hub of studio activity with two more movie studios built in Chennai, Vijaya Vauhini Studios and Gemini Studios.
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The serine family of amino acid includes: serine, cysteine, and glycine. Most microorganisms and plants obtain the sulfur for synthesizing methionine from the amino acid cysteine. Furthermore, the conversion of serine to glycine provides the carbons needed for the biosynthesis of the methionine and histidine. During serine biosynthesis, the enzyme phosphoglycerate dehydrogenase catalyzes the initial reaction that oxidizes 3-phospho-D- glycerate to yield 3-phosphonooxypyruvate.
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Bosseopentaenoic acid (Boseopentaen's), has 20 carbons and is a 5,8,10,12,14-pentaunsaturated fatty acid. C17H25CO2H, IUPAC organization name (5Z , 8Z , 10 E , 12E , 14Z)-eicosa-5,8,10,12,14-pentaenoic acid, numerical representation 20: 5 (5,8,10,12,14), n-6, molecular weight 302.46 g·mol−1.Burgess, J.R.; De la Rosa, R.I.; Jacobs, R.S.; Butler, A (1991). "A new eicosapentaenoic acid formed from arachidonic acid in the coralline red algae Bossiella orbigniana". Lipids.
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Otherwise: # Number the carbons in that chain starting from the end that is closest to the double bond. # Define the location k of the double bond as being the number of its first carbon. # Name the side groups (other than hydrogen) according to the appropriate rules. # Define the position of each side group as the number of the chain carbon it is attached to.
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These leave sp2-hybridized carbons that can partake in the π system of an aromatic molecule. Like neutral aromatic compounds, these compounds are stable and form easily. The cyclopentadienyl anion is formed very easily and thus 1,3-cyclopentadiene is a very acidic hydrocarbon with a pKa of 16. Other examples of aromatic ions include the cyclopropenium cation (2 π-electrons) and cyclooctatetraenyl dianion (10 π electrons).
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Module 2 adds another two carbons by the malonyl-CoA extender unit, followed by ketoreduction (KR) and dehydration. Module three adds a malonyl-CoA extender unit, followed by SAM-dependent methylation at C8, ketoreduction, and dehydration. Module 4 extends the molecule with a malonyl-CoA unit followed by ketoreduction. Assembly of monic acid is continued by the transfer of the 12C product of MmpD to MmpA.
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In that case, mirroring is equivalent to a half-turn rotation. For this reason, there are only three distinct 3-ketopentose stereoisomers, even though the molecule has two chiral carbons. Distinct stereoisomers that are not mirror-images of each other usually have different chemical properties, even in non-chiral environments. Therefore, each mirror pair and each non-chiral stereoisomer may be given a specific monosaccharide name.
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The skeletal formula of hexane, with carbons number one and three labelled The 3d ball representation of hexane, with carbon (black) and hydrogen (white) shown explicitly. NOTE: It doesn't matter which end of the chain you start numbering from, as long as you're consistent when drawing diagrams. The condensed formula or the IUPAC name will confirm the orientation. Some molecules will become familiar regardless of the orientation.
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The name is also used for any compound containing that group, namely R−CH=CH2 where R is any other group of atoms. An industrially important example is vinyl chloride, precursor to PVC, a plastic commonly known as vinyl. Chessboard made from polyvinyl chloride Vinyl is one of the alkenyl functional groups. On a carbon skeleton, sp2-hybridized carbons or positions are often called vinylic.
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Paracyclophanes adopt the boat conformation normally observed in cyclohexanes but are still able to retain aromaticity. The smaller the value of n the larger the deviation from aromatic planarity. In [6]paracyclophane which is one of the smallest, yet stable, cyclophanes X-ray crystallography shows that the aromatic bridgehead carbon atom makes an angle of 20.5° with the plane. The benzyl carbons deviate by another 20.2°.
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Docosapentaenoic acid (DPA) designates any straight chain 22:5 fatty acid, that is a straight chain open chain type of polyunsaturated fatty acid (PUFA) which contains 22 carbons and 5 double bonds. DPA is primarily used to designate two isomers, all-cis-4,7,10,13,16-docosapentaenoic acid (i.e. 4Z,7Z,10Z,13Z,16Z-docosapentaenoic acid) and all- cis-7,10,13,16,19-docosapentaenoic acid (i.e. 7Z,10Z,13Z,16Z,19Z-docosapentaenoic acid).
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371x371px Imines do not form simple cyclic silylene additions: benzo-fused NHSis react with the diimine and ortho carbons of N-tert-butyl phenylimine to form a five-membered ring composed of the NHSi silicon, one carbon and nitrogen of the imine and the ipso and para carbons of the phenyl group, through an intermediate that breaks the phenyl aromaticity. File:NHSi_with_imine.svg NHSis add across nitrile C-N bonds, first forming a three-membered ring, subsequently a second NHSi inserts to complete a 4-membered ring, similar to the reactivity of a alkyne. Alternatively, tert- butyl isocyanide reacts more like an alkyl halide with a single silicon bonding to the tert-butyl fragment and the carbon of the cyanide groups, or with two NHSis to from an acyclic tBu-Si-Si-CN product. There is evidence that the single-silicon NHSi-nitrile interconverts in small quantities to the silicon isonitrile.
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Spin labelled fatty acids have been extensively used to understand dynamic organization of lipids in bio-membranes and membrane biophysics. For example, stearic acid labelled with nitroxyl spin label moiety at various carbons (5,7,9,12,13,14 and 16th) with respect to first carbon of carbonyl group have been used to study the flexibility gradient of membrane lipids to understand membrane fluidity conditions at different depths of their lipid bilayer organization.
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Carbohydrate NMR spectroscopy addresses questions on the structure and conformation of carbohydrates. The analysis of carbohydrates by 1H NMR is challenging due to the limited variation in functional groups, which leads to 1H resonances concentrated in narrow bands of the NMR spectrum. In other words, there is poor spectral dispersion. The anomeric proton resonances are segregated from the others due to fact that the anomeric carbons bear two oxygen atoms.
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An illustration of the crystal packing for pentaindenocorannulene is given below. Pentaindenocorannulene X-ray crystal structure depiction Another geodesic polyarene that has been synthesized is C50H10. C50H10 can be described as a short, rigid, structurally pure [5,5] carbon nanotube. The crystal structure of C50H10 has been obtained. The carbons of the pentagon at the center of C50H10 have a POAV angle of 12.3°, less than that of pentaindenocorannulene.
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Fluorographene structure in chair conformation seen from above Fluorographene in chair structure seen from side Fluorographene (or perfluorographane, graphene fluoride) is a fluorocarbon derivative of graphene.Properties of Fluorinated Graphene Films It is a two dimensional carbon sheet of sp3 hybridized carbons, with each carbon atom bound to one fluorine. The chemical formula is . In comparison, Teflon (polytetrafluoroethylene), -(CF2)n-, consists of carbon "chains" with each carbon bound to two fluorines.
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Recent studies have also revealed that, similar to fluorination, full chlorination of graphene can be achieved. The resulting structure is called chlorographene. However other theoretical calculations questioned stability of chlorographene under ambient conditions. Also graphene can be fluorinated or halofluorinated by CVD-method with fluorocarbons, hydro- or halofluorocarbons by heating while in contact of carbon material with fluoroorganic substance to form partially fluorinated carbons (so called Fluocar materials).
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Fulcher CA, "MetaCyc Chimeric Pathway: superpathway of sialic acid and CMP-sialic acid biosynthesis", "MetaCyc, March 2009" In bacterial systems, sialic acids are biosynthesized by an aldolase enzyme. The enzyme uses a mannose derivative as a substrate, inserting three carbons from pyruvate into the resulting sialic acid structure. These enzymes can be used for chemoenzymatic synthesis of sialic acid derivatives. Biosynthesis of sialic acid by a bacterial aldolase enzyme.
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In general, two mechanisms have been suggested. Because Jacobsen’s catalyst epoxidizes conjugated alkenes (i.e. those in which there are multiple double bonds on alternating carbons) most effectively, the generally accepted mechanism is based on a radical intermediate which is stabilized due to the conjugated nature of the substrate. For non-conjugated alkenes, the substrate is far less able to stabilize a radical, making a radical intermediate more unlikely.
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Increased carbon length of the nitrogen R2 side chain alters activity. Side chain that is made out of three carbons has proven to be the most ideal length in terms of activity, increasing or decreasing the length of the chain from there has negative effect on biological activity. Alendronate, a common bisphosphonate drug, has a three carbon length side chain for example. Risedronate has heterocyclic structure containing nitrogen.
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The Boulton Carbon Company was a manufacturing company located in Cleveland, Ohio, USA, from 1881 to 1886. It was devoted to the manufacture of carbon points (or carbons) used for arc lighting. The company was organized in 1881 by W. H. Boulton and Willis U. Masters and formally incorporated in 1883. A controlling interest in the company was acquired in 1886 by a group of investors led by Washington H. Lawrence.
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The surface of the carbon nanotubes can be modified to reduce the hydrophobicity and improve interfacial adhesion to a bulk polymer through chemical attachment. Also surface of carbon nanotubes can be fluorinated or halofluorinated by CVD-method with fluorocarbons, hydro- or halofluorocarbons by heating while in contact of such carbon material with fluoroorganic substance to form partially fluorinated carbons (so called Fluocar materials) with grafted (halo)fluoroalkyl functionality.
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Likewise, estradiol undecylate (ester of 10 carbons) has a very extended duration, which is longer than that of all of the aforementioned esters. Polyestradiol phosphate is an atypical estradiol ester. It is a phosphoric acid ester of estradiol in the form of a polymer, with an average polymer chain length of approximately 13 repeat units of estradiol phosphate. It is slowly cleaved into estradiol and phosphoric acid by phosphatases.
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Structure of an ethene molecule, the simplest unsaturated hydrocarbon Unsaturated hydrocarbons are hydrocarbons that have double or triple covalent bonds between adjacent carbon atoms. The term "unsaturated" means more hydrogen atoms may be added to the hydrocarbon to make it saturated (i.e. consisting all single bonds). The configuration of an unsaturated carbons include straight chain, such as alkenes and alkynes, as well as branched chains and aromatic compounds.
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Harry Marsh is a leading figure in the world of carbon science. Born on 17 April 1926 in the north east of England, Marsh spent much of his career at the Northern Carbon Research Laboratories of the University of Newcastle upon Tyne. He is known for his work on the structure and adsorptive properties of carbons. At the 2006 meeting of the International Carbon Society he received their lifetime award.
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The dominant electronic interaction is the combination between the largest HOMO and the largest LUMO. Therefore, regioselectivity is governed by the atoms that bear the largest orbital HOMO and LUMO coefficients. For example, consider the cycloaddition of diazomethane to three dipolarophiles: methyl acrylate, styrene or methyl cinnamate. The carbon of diazomethane bears the largest HOMO, while the end olefinic carbons of methyl acrylate and styrene bear the largest LUMO.
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Fatty alcohols usually have an even number of carbon atoms and a single alcohol group (–OH) attached to the terminal carbon. Some are unsaturated and some are branched. They are widely used in industry. As with fatty acids, they are often referred to generically by the number of carbon atoms in the molecule, such as "a C12 alcohol", that is an alcohol having 12 carbons, for example dodecanol.
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Mudrocks form in various colors, including: red, purple, brown, yellow, green and grey, and even black. Shades of grey are most common in mudrocks, and darker colors of black come from organic carbons. Green mudrocks form in reducing conditions, where organic matter decomposes along with ferric iron. They can also be found in marine environments, where pelagic, or free-floating species, settle out of the water and decompose in the mudrock.
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Motility and sporulation were tested using hanging cell method and Dorner method, respectively, and both were found to be negative. The novel fatty acid composition was freed though a nicotinamide adenine dinucleotide phosphate containing solution. The composition was found to be C18:0, C 20:1, 2 carbons longer than any composition seen before. The optimum growth conditions are: temperature between 70 and 75 °C, freshwater, pH around 7.2.
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Note that to generate the ninhydrin chromophore (2-(1,3-dioxoindan-2-yl)iminoindane-1,3-dione), the amine is condensed with a molecule of ninhydrin to give a Schiff base. Thus only ammonia and primary amines can proceed past this step. At this step, there must be an alpha hydrogen present to form the Schiff base. Therefore, amines bound to tertiary carbons do not react further and thus are not detected.
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In dihaloelimination the electron donor (H2 in this case) is used to remove two halogens from adjacent carbons that are double bonded. 1,2,3-trichloropropane is reduced to allyl chloride by D. lykanthroporepellens, and further transformed abiotically to allyl alcohol in the presence of water (other abiotic reactions can occur). The carbon source has not been determined for this species but other organisms within Chloroflexi use CO2 as a carbon source.
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Glycine also does not have a β-carbon, while every other amino acid does. The α-carbon of an amino acid is significant in protein folding. When describing a protein, which is a chain of amino acids, one often approximates the location of each amino acid as the location of its α-carbon. In general, α-carbons of adjacent amino acids in a protein are about 3.8 ångströms (380 picometers) apart.
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Structure of pyridine N-oxide Oxidation of pyridine occurs at nitrogen to give pyridine-N-oxide. The oxidation can be achieved with peracids: :C5H5N + RCO3H -> C5H5NO + RCO2H Some electrophilic substitutions on the pyridine are usefully effected using pyridine-N-oxide followed by deoxygenation. Addition of oxygen suppresses further reactions at nitrogen atom and promotes substitution at the 2- and 4-carbons. The oxygen atom can then be removed, e.g.
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Linoleate has 18 carbons, is contained in many vegetable oils, particularly semi-drying oils, and is a cis-9-cis- 12-di-unsaturated fatty acid. C17H31CO2H, IUPAC organization name (9Z , 12Z)-octadeca- 9,12-dienoic acid, numerical representation 18: 2 (9,12), n-6, molecular weight 280.45, melting point -5 °C, specific gravity 0.902. CAS Registry Number 60-33-3. There is a double bond is conjugated as an isomer conjugated linoleic acid.
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Many of the physical properties of alkenes and alkanes are similar: they are colorless, nonpolar, and combustible. The physical state depends on molecular mass: like the corresponding saturated hydrocarbons, the simplest alkenes (ethylene, propylene, and butene) are gases at room temperature. Linear alkenes of approximately five to sixteen carbons are liquids, and higher alkenes are waxy solids. The melting point of the solids also increases with increase in molecular mass.
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This is mainly used for the manufacture of small alkenes (up to six carbons). Cracking of n-octane to give pentane and propene Related to this is catalytic dehydrogenation, where an alkane loses hydrogen at high temperatures to produce a corresponding alkene. This is the reverse of the catalytic hydrogenation of alkenes. Dehydrogenation of butane to give butadiene and isomers of butene This process is also known as reforming.
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Caldarchaeol is a membrane-spanning lipid found in hyperthermophilic archaea. Membranes made up of caldarchaeol are more stable since the hydrophobic chains are linked together, allowing the microorganisms to withstand high temperatures. It is also known as dibiphytanyldiglycerol tetraether. Two glycerol units are linked together by two strains which consist of two phytanes linked together to form a linear chain of 32 carbon atoms (40 carbons including methyl sidechains).
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Swamikannu Vincent, who had built the first cinema of South India in Coimbatore, introduced the concept of "Tent Cinema" in which a tent was erected on a stretch of open land close to a town or village to screen the films. The first of its kind was established in Madras, called "Edison's Grand Cinemamegaphone". This was due to the fact that electric carbons were used for motion picture projectors.
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Adding fillers (graphites, aluminum, or carbons) has recently allowed the thermal conductivity of EPS to reach around 0.030–0.034 (as low as 0.029) and as such has a grey/black color which distinguishes it from standard EPS. Several EPS producers have produced a variety of these increased thermal resistance EPS usage for this product in the UK & EU. Water vapor diffusion resistance (μ) of EPS is around 30–70.
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One isomer of lactic acid This animation focuses on one molecule of glucose turning into pyruvate then into lactic acid. In the process there is one 6-carbon glucose molecule and 2 NAD+ molecules. 2 phosphates attach to the ends of the glucose molecule, then glucose is split into 2 3-carbon pyruvate precursors. Subsequently, NAD+ molecules are converted into 2 NADH and additional phosphate groups are attached to the carbons.
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Sphingosine is a single-chain lipid (usually 18 carbons in length), rendering it to have sufficient solubility in water. This explains its ability to move between membranes and to flip-flop across a membrane. Estimates conducted at physiological pH show that approximately 70% of sphingosine remains in membranes while the remaining 30% is water-soluble. Sph that is formed has sufficient solubility in the liquid found inside cells (cytosol).
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Normally, activated carbons (R 1) are made in particulate form as powders or fine granules less than 1.0 mm in size with an average diameter between 0.15 and 0.25 mm. Thus they present a large surface to volume ratio with a small diffusion distance. Activated carbon (R 1) is defined as the activated carbon particles retained on a 50-mesh sieve (0.297 mm). PAC material is finer material.
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Many carbons preferentially adsorb small molecules. Iodine number is the most fundamental parameter used to characterize activated carbon performance. It is a measure of activity level (higher number indicates higher degree of activation) often reported in mg/g (typical range 500–1200 mg/g). It is a measure of the micropore content of the activated carbon (0 to 20 Å, or up to 2 nm) by adsorption of iodine from solution.
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It was synthesized by Leo Paquette in 1982, primarily for the "aesthetically pleasing symmetry of the dodecahedral framework". For many years, dodecahedrane was the simplest real carbon-based molecule with full icosahedral symmetry. Buckminsterfullerene (), discovered in 1985, also has the same symmetry, but has three times as many carbons and 50% more atoms overall. The synthesis of the C20 fullerene in 2000, from brominated dodecahedrane, may have demoted to second place.
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Nylon 6 can be modified using comonomers or stabilizers during polymerization to introduce new chain end or functional groups, which changes the reactivity and chemical properties. It's often done to change its dyeability or flame retardance."Synthesis of Modified Polyamides (Nylon 6)", NPTEL (National Programme On Technology Enhanced Learning), retrieved May 9, 2016 Nylon 6 is synthesized by ring-opening polymerization of caprolactam. Caprolactam has 6 carbons, hence Nylon 6.
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A variety of metabolic modes exist capable of degrading chlorinated aliphatic compounds. Anaerobic reduction, oxidation of the compound, and cometabolism under aerobic conditions are the three main metabolic modes utilized by microorganisms to degrade chlorinated aliphatic compounds. Organisms that can readily metabolize chlorinated aliphatic compounds are not common in the environment. One and two carbons that have little chlorination are the compounds most effectively metabolized by soil microbial populations.
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Another useful way of determining how many protons a carbon in a molecule is bonded to is to use an attached proton test (APT), which distinguishes between carbon atoms with even or odd number of attached hydrogens. A proper spin-echo sequence is able to distinguish between S, I2S and I1S, I3S spin systems: the first will appear as positive peaks in the spectrum, while the latter as negative peaks (pointing downwards), while retaining relative simplicity in the spectrum since it is still broadband proton decoupled. Even though this technique does not distinguish fully between CHn groups, it is so easy and reliable that it is frequently employed as a first attempt to assign peaks in the spectrum and elucidate the structure. Additionally, signals from quaternary carbons and other carbons with no attached protons are still detectable, so in many cases an additional conventional 13C spectrum is not required, which is an advantage over DEPT.
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They are inert, and because they are resorbable and active, the materials can remain in the body unchanged. They can also dissolve and actively take part in physiological processes, for example, when hydroxylapatite, a material chemically similar to bone structure, can integrate and help bone grow into it. Common materials used for bioceramics include alumina, zirconia, calcium phosphate, glass ceramics, and pyrolytic carbons. One important use of bioceramics is in hip replacement surgery.
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In 1886, Lawrence returned to the carbon manufacturing business when he purchased the controlling interest in the Boulton Carbon Company from W. H. Boulton. The company had been started by Boulton, the former manager of the carbon department of Brush Electric. In 1881, Boulton left Brush and partnered with Cleveland businessman Willis U. Masters to form the new company. Boulton's primary product was carbon electrodes, known as "carbon points" or simply "carbons".
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Romeo Kreinberg is an American–German business executive and former executive vice president for Performance Plastics & Chemicals at the Dow Chemical Company. Kreinberg was instrumental in the Fortune 100 company's reorganization in the 2000s. He serves as chairman of Befesa, an industrial waste manager and recycler, and Rain Carbon a manufacturer of chemical raw materials made from coal tar. Kreinberg is also a director of Orion Engineered Carbons and a former director of Dow Corning.
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The addition of free radical scavengers or antioxidants can lead to amphotericin resistance in some species, such as Scedosporium prolificans, without affecting the cell wall. Two amphotericins, amphotericin A and amphotericin B, are known, but only B is used clinically, because it is significantly more active in vivo. Amphotericin A is almost identical to amphotericin B (having a C=C double bond between the 27th and 28th carbons), but has little antifungal activity.
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See lithium-halogen exchange (under Reactivity and applications) A third method to prepare organolithium reagents is through lithium halogen exchange. tert-butyllithium or n-butyllithium are the most commonly used reagents for generating new organolithium species through lithium halogen exchange. Lithium-halogen exchange is mostly used to convert aryl and alkenyl iodides and bromides with sp2 carbons to the corresponding organolithium compounds. The reaction is extremely fast, and often proceed at -60 to -120 °C.
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Although the original explanation only invoked the orbital on the atom α to the dienophile double bond, Salem and Houk have subsequently proposed that orbitals on the α and β carbons both participate when molecular geometry allows. 400x400px Often, as with highly substituted dienes, very bulky dienophiles, or reversible reactions (as in the case of furan as diene), steric effects can override the normal endo selectivity in favor of the exo isomer.
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The outbreak of World War I transformed GEC into a major player in the electrical industry. It was heavily involved in the war effort, with products such as radios, signal lamps, and the arc-lamp carbons used in searchlights. Between the wars, GEC expanded to become a global corporation and national institution. The takeover of Fraser and Chalmers in 1918 took GEC into heavy engineering and bolstered their claim to supply 'everything electrical'.
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Lesquerolic acid is a hydroxy acid that occurs naturally in Paysonia lasiocarpa and other Paysonia and Physaria species. It was first isolated in 1961 by a team from the Northern Regional Research Laboratory. This compound has the R configuration at the alcohol-bearing stereocenter, and it is of the Z configuration at the olefin. Lesquerolic acid is chemically similar to ricinoleic acid, but with two additional carbons at the carboxyl end of the carbon chain.
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He investigated the stability of radicals on trivalent carbons leading him to study organometallic compounds and their application in his research. He also worked on the syntheses of multi-membered ring systems. including the Nobel Lecture, December 12, 1963 Consequences and Development of an Invention In 1933 Ziegler published his first major work on large ring systems, "Vielgliedrige Ringsysteme" which presented the fundamentals for the Ruggli-Ziegler dilution principle. Max Planck Institute for Coal Research.
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It is a colorless liquid with a pleasant odor. Because the carbon atom connected to the bromine is connected to two other carbons the molecule is referred to as a secondary alkyl halide. 2-Bromobutane is relatively stable, but is toxic and flammable. When treated with a strong base, it is prone to undergo an E2 reaction, which is a bimolecular elimination reaction, resulting in (predominantly) 2-butene, an alkene (double bond).
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Laboratory synthesis of ICZs has been a topic of great interest since their discovery. Unfortunately, due to the somewhat complex nature of the molecule and the high level of reactivity of carbons on indole molecules, a facile high yield synthesis has yet to be found. Despite this, there have been many ways found to produce this compound in its various forms. Of special interest is one of the better REB syntheses, found in 1999.
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It is the most abundant source of sugar in nature and is a major part of the paper industry. Starch is also a polysaccharide made up of glucose monomers; however, they are connected via an alpha 1-4 linkage instead of beta. Starches, particularly amylase, are important in many industries, including the paper, cosmetic, and food. Chitin is a derivation of cellulose, possessing an acetamide group instead of an –OH on one of its carbons.
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Sugar polymers can be linear or branched and are typically joined with glycosidic bonds. The exact placement of the linkage can vary, and the orientation of the linking functional groups is also important, resulting in α- and β-glycosidic bonds with numbering definitive of the linking carbons' location in the ring. In addition, many saccharide units can undergo various chemical modifications, such as amination, and can even form parts of other molecules, such as glycoproteins.
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Nervonic acid is a monounsaturated odd-chain fatty acid, which serves as a biomarker for certain human disorders. The most common OCFA are the saturated C15 and C17 derivatives, respectively pentadecanoic acid and heptadecanoic acid. The synthesis of even-chained fatty acid synthesis is done by assembling acetyl- CoA precursors. Because the segments are each two carbons in length the resulting fatty acid has an even number of carbon atoms in it.
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Vicinal difunctionalization refers to a chemical reaction involving transformations at two adjacent centers (most commonly carbons). This transformation can be accomplished in α,β-unsaturated carbonyl compounds via the conjugate addition of a nucleophile to the β-position followed by trapping of the resulting enolate with an electrophile at the α-position. When the nucleophile is an enolate and the electrophile a proton, the reaction is called Michael addition.Chapdelaine, M. J.; Hulce, M. Org. React.
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Steric approach control is common in conjugate addition reactions. Thus, in cyclic substrates, a trans relationship between substituents on the α- and β-carbons is common. The configuration at the α-position is less predictable, especially in cases when epimerization can occur. On the basis of steric approach control, the new α-substituent is predicted to be trans to the new β-substituent, and this is observed in a number of cases.
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Once the fatty acid chain reaches 16 or 18 carbons long after cycles of elongation, termination occurs. In the final round of elongation, rather than being taken back to the KS domain, the fatty acid product, which is still bound to ACP, is taken from the ER domain to the MPT domain. Here, CoA is attached to the fatty acid, and the resulting long chain fatty acyl-CoA is released into the cytosol.
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In pyrrole, each of the four sp2-hybridized carbons contributes one π-electron, and the nitrogen atom is also sp2-hybridized and contributes two π-electrons from its lone pair, which occupies a p-orbital. In imidazole, both nitrogens are sp2-hybridized; the one in the double bond contributes one electron and the one which is not in the double bond and is in a lone pair contributes two electrons to the π system.
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Thermal depolymerization (TDP) is a depolymerization process using hydrous pyrolysis for the reduction of complex organic materials (usually waste products of various sorts, often biomass and plastic) into light crude oil. It mimics the natural geological processes thought to be involved in the production of fossil fuels. Under pressure and heat, long chain polymers of hydrogen, oxygen, and carbon decompose into short-chain petroleum hydrocarbons with a maximum length of around 18 carbons.
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For some time, researchers believed that large hydrocarbon molecules were impervious to hydrogen exchange, but recent work has identified many reactions that allow isotope reordering. The isotopic exchange becomes relevant at geological time scales and has impacted work of biologists studying lipid biomarkers as well as geologists studying ancient oil. Reactions responsible for exchange include The trend of carbocation stability. Note the stabilization effects from adjacent carbons that donate electrons to the positive charge.
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Agrium manufactures nitrogen fertilizer in its Borger plant. Borger also has Sid Richardson Carbon Company, which produces rubber- grade carbon black used to strengthen rubber tires, and Orion Engineered Carbons, Inc., which produces a variety of carbon blacks at its Borger facility. The original townsite is said to have been founded around 1898 by John F. Weatherly, a rancher who built a dugout and gave the future town the grandiose name of Granada.
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The examples of the reactions shown below also show that the stereocenters of the α carbons remain intact while double bonds, especially trisubsituted double bonds do not undergo E/Z–isomerization in the reaction. :Scope Lower yields are obtained for reactions involving aliphatic α,β-unsaturated and more hydrophilic aldehydes. Double bonds and electron-rich aldehyde substrates can lead to chlorination as an alternate reaction. The use of DMSO in these cases gives better yield.
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Biosynthesis of oxylipins is initiated by dioxygenases or monooxygenases; however also non-enzymatic autoxidative processes contribute to oxylipin formation (phytoprostanes, isoprostanes). Dioxygenases include lipoxygenases (plants, animals, fungi), heme-dependent fatty acid oxygenases (plants, fungi), and cyclooxygenases (animals). Fatty acid hydroperoxides or endoperoxides are formed by action of these enzymes. Monooxygenases involved in oxylipin biosynthesis are members of the cytochrome P450 superfamily and can oxidize double bonds with epoxide formation or saturated carbons forming alcohols.
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Watson-Crick base pairs in a siRNA (hydrogen atoms are not shown) Each nucleotide in RNA contains a ribose sugar, with carbons numbered 1' through 5'. A base is attached to the 1' position, in general, adenine (A), cytosine (C), guanine (G), or uracil (U). Adenine and guanine are purines, cytosine and uracil are pyrimidines. A phosphate group is attached to the 3' position of one ribose and the 5' position of the next.
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If the carbonyl is at position 1 (that is, n or m is zero), the molecule begins with a formyl group H(C=O)− and is technically an aldehyde. In that case, the compound is termed an aldose. Otherwise, the molecule has a keto group, a carbonyl −(C=O)− between two carbons; then it is formally a ketone, and is termed a ketose. Ketoses of biological interest usually have the carbonyl at position 2.
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Surflon S-111 is synthesized in Japan by oxidizing a mixture of fluorotelomer olefins. Fluorotelomer olefins are synthesized using a telomerization of tetrafluoroethylene taxogens (monomers), followed by an ethylene insertion. The olefin is oxidized, removing one carbon to yield products with an odd number of carbons with even-lengthed fluorocarbon chains plus a carboxylic acid group. As the fluorotelomer olefins are dominated by F(CF2)8CH=CH2, PFNA is the major PFCA product.
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In some PAHs, like naphthalene, anthracene, and coronene, all carbon and hydrogen atoms lie on the same plane. This geometry is a consequence of the fact that the σ-bonds that result from the merger of sp2 hybrid orbitals of adjacent carbons lie on the same plane as the carbon atom. Those compounds are achiral, since the plane of the molecule is a symmetry plane. However, some other PAHs are not planar.
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The difference between GTX and STX is that on the carbon at position 11, a hydrogensulfate is bound. Between dcSTX, NSTX and GTX, dcSTX is the one which varies most from saxitoxin. In dcSTX there is a double bond between carbons 2 and 3, while there is a single bond in STX. This also results in that the double-bonded N to carbon number 3 in STX, is a single bound NH2 in dcSTX.
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The name pagodane is used more generally for any member of a family of compounds whose molecular skeletons have the same 16-carbon central cage as the basic compound. Each member can be seen as the result of connecting eight atoms of this cage in pairs by four alkane chains. The general member is denoted [m.n.p.q]pagodane where m, n, p and q are the number of carbons of those four chains.
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If a perfluorinated compound has a fluorinated tail, but also a few non-fluorinated carbons (typically two) near the functional group, it is called a fluorotelomer (such molecules are commercially treated as perfluorinated), but such molecules are more of industrial value than chemical. The chain end may similarly be attached to different functional groups (via the hydrogenized terminal carbon), such as hydroxyl resulting in fluorotelomer alcohols, sulfonate resulting in fluorotelomer sulfonates, etc.
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These cations differ with respect to the relative positions of the pair of sulfur atoms. Both isomers feature a planar ring, which is aromatic owing to the presence of 6π electrons. For example, the 1,2-ditholium ring can be represented as an allyl cation of the three carbons, with each sulfur atom donating one of its lone pairs of electrons to give a total of three pairs. Structure of diphenyl-1,2-dithiolium cation (as its bisulfate salt).
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500px 500px Two molecules of farnesyl pyrophosphate then condense to form squalene by the action of squalene synthase in the endoplasmic reticulum. 500px 500px Oxidosqualene cyclase then cyclizes squalene to form lanosterol. Finally, lanosterol is converted to cholesterol through a 19-step process. 500px 500px 500px The final 19 steps to cholesterol contain NADPH and oxygen to help oxidize methyl groups for removal of carbons, mutases to move alkene groups, and NADH to help reduce ketones.
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As a result, boroles exhibit unique electronic properties not found in other metalloles. The parent unsubstituted compound with the chemical formula C4H4BH has yet to be isolated outside a coordination sphere of transition metals. Substituted derivatives, which have been synthesized, can have various substituents at the 4 carbons and boron. The high electron deficiency leads to interesting reactivities such as metal free hydrogen activation and rearrangements upon cycloaddition which are unobserved in other structural analogues like pyrrole or furan.
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Typically, the number of carbons and the number of double bonds are also listed in short descriptions of unsaturated fatty acids. For instance, ω-3 18:4, or 18:4 ω-3, or 18:4 n−3 indicates stearidonic acid, an 18-carbon chain with 4 double bonds, and with a double bond between the third and fourth carbon atoms from the CH3 end. Double bonds are cis and separated by a single methylene (CH2) group unless otherwise noted.
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The lipids will then "aggregate" and form various phases and structures. According to the conditions (concentration, temperature, ionic strength of solution, etc.) and the chemical structures of the lipid, different phases will be observed. For instance, the lipid POPC (palmitoyl oleyl phosphatidyl choline) tends to form lamellar vesicles in solution, whereas smaller lipids (lipids with shorter acyl chains, up to 8 carbons in length), such as detergents, will form micelles if the CMC (critical micelle concentration) is reached.
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1,1-Ethanedithiol has several reactions known that are important in white wine flavours. In the presence of oxygen, 1,1-ethanedithiol is converted to cis/trans-3,6-dimethyl-1,2,4,5-tetrathiane which has a rubbery aroma. This molecule has a ring with four sulfur atoms and two carbons, two 1,1-ethanedithiol molecules become linked at their sulfur atoms with the loss of hydrogen. This can further oxidise to cis/trans-3,6-dimethyl-1,2,5-trithiolane which has a meat-like odour.
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Electrophilic attack to allene groups. Adapted from In the electrophilic attack of allenes, it takes place in a manner that prefers to form a terminal adduct and the vinyl cation at the central carbon. The polarization of the allene group show that the terminal carbons have a higher electron density and tendency to under nucleophillic attack. However, if the terminal end is stabilized by a substituent, an allyl-like cation may form as the electrophile attacks the central carbon.
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An example fatty alcohol Fatty alcohols (or long-chain alcohols) are usually high-molecular-weight, straight-chain primary alcohols, but can also range from as few as 4–6 carbons to as many as 22–26, derived from natural fats and oils. The precise chain length varies with the source. Some commercially important fatty alcohols are lauryl, stearyl, and oleyl alcohols. They are colourless oily liquids(for smaller carbon numbers) or waxy solids, although impure samples may appear yellow.
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Tropane is a nitrogenous bicyclic organic compound. It is mainly known for a group of alkaloids derived from it (called tropane alkaloids), which include, among others, atropine and cocaine. Tropane alkaloids occur in plants of the families Erythroxylaceae (including coca) and Solanaceae (including mandrake, henbane, deadly nightshade, datura, potato, tomato). The nitrogen bridge is between C-1 and C-5; these two are asymmetric carbons, but tropane is optically inactive due to mirror symmetry. 8-Azabicyclo[3.2.
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A third approach is to adsorb molecular hydrogen on the surface of a solid storage material. Unlike in the hydrides mentioned above, the hydrogen does not dissociate/recombine upon charging/discharging the storage system, and hence does not suffer from the kinetic limitations of many hydride storage systems. Hydrogen densities similar to liquefied hydrogen can be achieved with appropriate adsorbent materials. Some suggested adsorbents include activated carbon, nanostructured carbons (including CNTs), MOFs, and hydrogen clathrate hydrate.
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Carbons from dietary fructose are found in both the free fatty acid and glycerol moieties of plasma triglycerides. High fructose consumption can lead to excess pyruvate production, causing a buildup of Krebs cycle intermediates. Accumulated citrate can be transported from the mitochondria into the cytosol of hepatocytes, converted to acetyl CoA by citrate lyase and directed toward fatty acid synthesis. In addition, DHAP can be converted to glycerol 3-phosphate, providing the glycerol backbone for the triglyceride molecule.
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Care must be taken to not over reduce the silicon; often triethylamine is added to prevent over reduction. The yield for this reduction can be as high as 80%. N-heterocyclic silylenes containing Silicon(II) with four-membered rings (1 carbon) and six- membered rings (3 carbons) are well known and derived from the reactions of SiX4 with amidinate and NacNac ligands respectively. The silylenes synthesized prior to West and Denk's first NHSi decomposed at temperatures below 77K.
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Structures of the significant conformations are shown: chair (1), half-chair (2), twist-boat (3) and boat (4). When ring flip happens completely from chair-to-chair, hydrogens that were previously axial (blue H in upper-left structure) turn equatorial and equatorial ones (red H in upper- left structure) turn axial. Each carbon bears one "up" and one "down" hydrogen. The C-H bonds in successive carbons are thus staggered so that there is little torsional strain.
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Judge Wyzanski's correspondence is with friends and associates and is of a personal-professional nature. It includes both letters received and carbons of letters sent. Many of the people under whom Wyzanski worked, such as United States Court of Appeals Judges Augustus Noble Hand and Learned Hand, or his teachers at the Harvard Law School such as Felix Frankfurter, became close friends of his. Correspondence concerns Wyzanski's professional and personal life, national matters, and Harvard affairs.
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Eicosapentaenoic acid (EPA) has 20 carbons, is found in fish oil, is a pentaunsaturated fatty acid. It is one of the essential fatty acids. The recommendation of ingesting fish oil supplements during pregnancy is said to help increase the cognitive ability at 6 months, but mercury concentration in fish products offsets the effect. In patients with hyperlipidemia and obstructive artery disease it can help lower triglycerides and also has an anti-platelet effect similar to other anti- platelet agents.
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Cervonic acid (or docosahexaenoic acid) has 22 carbons, is found in fish oil, is a 4,7,10,13,16,19-hexa unsaturated fatty acid. In the human body its generation depends on consumption of omega 3 essential fatty acids (e.g., ALA or EPA), but the conversion process is inefficient. C21H31CO2H, IUPAC organization name (4Z, 7Z, 10Z, 13Z, 16Z, 19Z)-docosa-4,7,10,13,16,19-hexaenoic acid, numerical representation 22: 6 (4, 7,10,13,16,19), n-3, molecular weight 328.49, melting point -44 °C, specific gravity 0.950.
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In terms of valence bond theory, in each carbon atom the 2s orbital hybridizes with one 2p orbital thus forming an sp hybrid. The other two 2p orbitals remain unhybridized. The two ends of the two sp hybrid orbital overlap to form a strong σ valence bond between the carbons, while on each of the other two ends hydrogen atoms attach also by σ bonds. The two unchanged 2p orbitals form a pair of weaker π bonds.
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There are two types of bonds involved in a glycoprotein: bonds between the saccharides residues in the glycan and the linkage between the glycan chain and the protein molecule. The sugar moieties are linked to one another in the glycan chain via glycosidic bonds. These bonds are typically formed between carbons 1 and 4 of the sugar molecules. The formation of glycosidic bond is energetically unfavourable, therefore the reaction is coupled to the hydrolysis of two ATP molecules.
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Its properties are determined by the R and R' groups in the monomers. In nylon 6,6, R = 4C and R' = 6C alkanes, but one also has to include the two carboxyl carbons in the diacid to get the number it donates to the chain. In Kevlar, both R and R' are benzene rings. Industrial synthesis is usually done by heating the acids, amines or lactams to remove water, but in the laboratory, diacid chlorides can be reacted with diamines.
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Lipid A consists of two glucosamine (carbohydrate/sugar) units, in an β(1→6) linkage, with attached acyl chains ("fatty acids"), and normally containing one phosphate group on each carbohydrate. The optimal immune activating lipid A structure is believed to contain 6 acyl chains. Four acyl chains attached directly to the glucosamine sugars are beta hydroxy acyl chains usually between 10 and 16 carbons in length. Two additional acyl chains are often attached to the beta hydroxy group.
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The port is directly connected to the Spanish enclave Melilla: the Port of Melilla uses approximately 70% of the wet area, while Nador port uses the remaining 30% of the south-east area. The port is used as ferry/ro-ro port, dry-bulk and has facilities for hydro-carbons. The ro-ro facilities are used by ferry operators on the route to/from Spain. In 1994 the operator FerriMaroc opened the line to the Port of Almeria.
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Along this pathway, many products can be formed, including the flavonols, flavan-3-ols, proanthocyanidins (tannins) and a host of other various polyphenolics. Biosynthesis of catechin Flavanoids can possess chiral carbons. Methods of analysis should take this element into accountMethods of analysis and separation of chiral flavonoids. Jaime A. Yáñeza, Preston K. Andrewsb and Neal M. Journal of Chromatography B, Volume 848, Issue 2, 1 April 2007, Pages 159-181 especially regarding bioactivity or enzyme stereospecificity.
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The triazines have planar six-membered benzene-like ring but with three carbons replaced by nitrogens. The three isomers of triazine are distinguished by the positions of their nitrogen atoms, and are referred to as 1,2,3-triazine, 1,2,4-triazine, and 1,3,5-triazine. Other aromatic nitrogen heterocycles are pyridines with one ring nitrogen atom, diazines with 2 nitrogen atoms in the ring, triazoles with 3 nitrogens in a 5 membered ring, and tetrazines with 4 ring nitrogen atoms.
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Brian Stableford, "Stanley G. Weinbaum: The Lost Pioneer," in Outside The Human Aquarium: Masters of Science Fiction, Wildside Press (2006), p.129. It was reissued in paperback by Harlequin Books in 1953, followed by an Avon Books edition in 1970. French translations were published in 1956 and 1972.ISFDB bibliography In 1995, Tachyon Publications issued a substantially longer "restored edition" from carbons of Weinbaum's original manuscript, found in a trunk of Weinbaum's papers held by his grandson.
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The methylglyoxal reacts spontaneously with reduced glutathione (or its equivalent, trypanothione),) forming a hemithioacetal. The glyoxalase system converts such compounds into D-lactate and restored the glutathione. In this conversion, the two carbonyl carbons of the 2-oxoaldehyde are oxidized and reduced, respectively, the aldehyde being oxidized to a carboxylic acid and the acetal group being reduced to an alcohol. The glyoxalase system evolved very early in life's history and is found nearly universally through life- forms.
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Its reversibility enables it to quickly activate and inhibit itself, making the molecule a specific inhibitor both in vitro and in cellulo. Pyr1 can be described as a tetracyclic molecule with a simple structure. Its few radicals are widely expanded along the benzene rings, distinguishing a benzoyloxy group in the ninth carbon and two methyl radicals in carbon five and eleven. There is also a ketone group in carbon one and two hydrogen radicals in carbons two and six.
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For example, there are 16 distinct aldohexose stereoisomers, but the name "glucose" means a specific pair of mirror-image aldohexoses. In the Fischer projection, one of the two glucose isomers has the hydroxyl at left on C3, and at right on C4 and C5; while the other isomer has the reversed pattern. These specific monosaccharide names have conventional three-letter abbreviations, like "Glu" for glucose and "Thr" for threose. Generally, a monosaccharide with n asymmetrical carbons has 2n stereoisomers.
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Durrell had sent out proofs and carbons of Mountolive to a few people whose opinions he valued. Richard Aldington praised the long letter from Pursewarden to Mountolive (V), and the mourning of the Coptic women. Henry Miller admired the description of the slaughter of the camels (V), and Gerald Sykes, the novelist and New York Times reviewer, found the fish drive (I) "in [Durrell's] best manner." Early reviews, following the publication date of 10 October 1958, contained contradictions.
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In organic chemistry, bilane is a compound with the formula or . It is a tetrapyrrole, a class of compounds with four independent pyrrole rings. Specifically, the molecule can be described as four pyrrole molecules connected in an open chain by three methylene bridges at carbons adjacent to the nitrogens, replacing the respective hydrogens. The name is also used for the class of compounds formally derived from bilane proper by replacement of some additional hydrogen atoms by various functional groups.
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Two fatty acids, linoleic acid and alpha-linolenic acid, are considered essential fatty acids (EFAs) in humans and other mammals. Both are 18 carbon fatty acids unlike mead acid, which has 20 carbons. Linoleic is an ω-6 fatty acid whereas linolenic is ω-3 and mead is ω-9. One study examined patients with intestinal fat malabsorption and suspected EFA deficiency; they were found to have blood-levels of mead acid 1,263% higher than reference subjects.
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3-Ketoacyl-CoA synthase I in Arabidopsis thaliana is involved in very long chain fatty acid synthesis, which plays a role in wax biosynthesis. The enzyme catalyzes the following reaction: very-long-chain acyl-CoA + malonyl-CoA ⇒ very-long-chain 3-oxoacyl- CoA + CoA + CO2 It is an elongase that appears to be involved in the production of very-long-chain fatty acids that are 26 carbons and longer. Mefluidide and perfluidone are selective inhibitors of this enzyme.
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0]hexyl cation is analogous to the previously well-studied aromatic cyclopropenyl cation. Like the cyclopropenyl cation, positive charge is delocalized over three equivalent carbons containing two π electrons. This electronic configuration thus satisfies Huckel's rule (requiring 4n+2 π electrons) for aromaticity. Indeed, Winstein noticed that the only fundamental difference between this aromatic propenyl cation and his non-classical hexyl cation was the fact that, in the latter ion, conjugation is interrupted by three -- units.
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Carbon materials have been widely used as cathodes because of their excellent electrical conductivities, large surface areas, and chemical stability. Especially relevant for lithium-air batteries, carbon materials act as substrates for supporting metal oxides. Binder-free electrospun carbon nanofibers are particularly good potential candidates to be used in electrodes in lithium-oxygen batteries because they have no binders, have open macroporous structures, have carbons that support and catalyze the oxygen reduction reactions, and have versatility. Zhu et al.
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Here, though actually carbon 1 & 2 are lost by oxidation. The new Carbon 1 has now become a CCOH similar to the parent compound, looking as if just carbon 2 & 3 have been removed from the parent compound. "Dinor" does not have to be reduction in adjacent carbons e.g. 5-Acetyl-4,18-dinor-retinoic acid, where 4 referred to a ring carbon and 18 referred to a methyl group on the 5th carbon on the ring.
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Rumenic acid, one of the 28 conjugated isomers of linoleic acid Conjugated fatty acids are polyunsaturated fatty acids in which at least one pair of double bonds is separated by only one single bond. The conjugation implies four consecutive unsaturated links (i.e., CH rather than CH2 groups), and results in a delocalization of electrons along the double-bonded carbons. An example of a conjugated fatty acid is the rumenic acid, found in the meat and milk of ruminants.
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Since the percentage of 13C is so low in natural isotopic abundance samples, the 13C coupling effects on other carbons and on 1H are usually negligible, and for all practical purposes splitting of 1H signals due to coupling with natural isotopic abundance carbon does not show up in 1H NMR spectra. In real life, however, the 13C coupling effect does show up on non-13C decoupled spectra of other magnetic nuclei, causing satellite signals. Similarly for all practical purposes, 13C signal splitting due to coupling with nearby natural isotopic abundance carbons is negligible in 13C NMR spectra. However, practically all hydrogen bonded to carbon atoms is 1H in natural isotopic abundance samples, including any 13C nuclei bonded to H atoms. In a 13C spectrum with no decoupling at all, each of the 13C signals is split according to how many H atoms that C atom is next to. In order to simplify the spectrum, 13C NMR spectroscopy is most often run fully proton decoupled, meaning 1H nuclei in the sample are broadly irradiated to fully decouple them from the 13C nuclei being analyzed.
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SWNTs have a high theoretical specific surface area of 1315 m2/g, while that for MWNTs is lower and is determined by the diameter of the tubes and degree of nesting, compared with a surface area of about 3000 m2/g of activated carbons. Nevertheless, CNTs have higher capacitance than activated carbon electrodes, e.g., 102 F/g for MWNTs and 180 F/g for SWNTs. MWNTs have mesopores that allow for easy access of ions at the electrode–electrolyte interface.
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The most popular aqueous phase carbons are bituminous based because of their hardness, abrasion resistance, pore size distribution, and low cost, but their effectiveness needs to be tested in each application to determine the optimal product. Activated carbon is used for adsorption of organic substances and non-polar adsorbates and it is also usually used for waste gas (and waste water) treatment. It is the most widely used adsorbent since most of its chemical (e.g. surface groups) and physical properties (e.g.
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A few molecules have a tetrahedral geometry with no central atom. An inorganic example is tetraphosphorus () which has four phosphorus atoms at the vertices of a tetrahedron and each bonded to the other three. An organic example is tetrahedrane () with four carbon atoms each bonded to one hydrogen and the other three carbons. In this case the theoretical C−C−C bond angle is just 60° (in practice the angle will be larger due to bent bonds), representing a large degree of strain.
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Isoelectronic species have same bond number. In molecules which have resonance or nonclassical bonding, bond number may not be an integer. In benzene, the delocalized molecular orbitals contain 6 pi electrons over six carbons essentially yielding half a pi bond together with the sigma bond for each pair of carbon atoms, giving a calculated bond number of 1.5. Furthermore, bond numbers of 1.1, for example, can arise under complex scenarios and essentially refer to bond strength relative to bonds with order 1.
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The aerobic metabolism of alkanes is carried out through the terminal alkane oxidation pathway, where monooxygenases initiate the oxidation of terminal carbons. This sequential pathway first produces alcohols, then alcohol and aldehyde dehydrogenases, and ultimately aldehydes and fatty acids, respectively. Following an oil spill, huge imbalances in the carbon/nitrogen and carbon/phosphorus ratios can be observed. For this, A. borkumensis have a myriad of transport proteins that allow fast uptake of key nutrients that are limiting in the environment.
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In many modern studies, the Polanyi theory is widely used in the study of activated carbons, or carbon black. The theory has been successfully used to model a variety of scenarios such as the gas adsorption on activated carbon and the adsorption process of nonionic Polycyclic aromatic hydrocarbons. Later on, experiments also showed that it can model ionic polycyclic aromatic hydrocarbons such as phenols and anilines. More recently, the Polyani adsorption isotherm has been used to model to adsorption of carbon nanoparticles.
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The region of a contorted molecule having saturated hydrogens and carbons is known as bay region (having white spheres or saturated hydrogens) Figure 4. Another reason for making the PAHs molecules contorted may be the size of these molecules. Theoretical vibrational frequency studies of C6n2 H6n (n=2-12) on coronenes using quantum chemical calculation (Hartree-Fock and DFT) show accelerated loss of planarity on increasing size of PAH molecules in-spite of having a stable structure due to conjugation, delocalization and aromatization.
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These results can be predicted with FMO theory by observing the interaction between the HOMO and LUMO of the species. To use FMO theory, the reaction should be considered as two separate ideas: (1) whether or not the reaction is allowed, and (2) which mechanism the reaction proceeds through. In the case of a [1,5] shift on pentadiene, the HOMO of the sigma bond (i.e. a constructive bond) and the LUMO of butadiene on the remaining 4 carbons is observed.
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Cetalkonium chloride (CKC) is a quaternary ammonium compound of the alkyl- benzyldimethylammonium chloride family, the alkyl group having a chain length of C16 (16 carbons). It is used in pharmaceutical products either as an excipient (Cationorm, Retaine MGD) or as an active ingredient (Bonjela, Pansoral). It may be found in very small amount in the excipient benzalkonium chloride mixture (typically less than 5% of the total mixture). Cetalkonium chloride is purchased as a raw material in dry form as a white powder.
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The alcohol "3-propanol" is not another isomer, since the difference between it and 1-propanol is not real; it is only the result of an arbitrary choice in the ordering of the carbons along the chain. For the same reason, "ethoxymethane" is not another isomer. 1-Propanol and 2-propanol are examples of positional isomers, which differ by the position at which certain features, such as double bonds or functional groups, occur on a "parent" molecule (propane, in that case).
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Conflict has arisen between those who would protect the few remaining populations and those who would rather use its critical habitat for economic activities. Certain subspecies of L. floccosa have been used to improve a meadowfoam cultivar derived from Limnanthes alba. The crop is grown for its seed oil, which contains long chain fatty acids (greater than 20 carbons), has high oxidative stability, does not have any odor and is highly emollient. The oil is currently used in cosmetics manufacturing.
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In 1995 the preparation of carbyne chains with over 300 carbons was reported using this technique. However the report has been contested by a claim that the detected molecules were fullerene-like structures rather than long polyynes. Polyyne chains have also been stabilised to heating by co-deposition with silver nanoparticles, and by complexation with a mercury-containing tridentate Lewis acid to form layered adducts. Long polyyne chains encapsulated in double-walled carbon nanotubes have also been shown to be stable.
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Coumarin () or 2H-chromen-2-one is an aromatic organic chemical compound with formula . Its molecule can be described as a benzene molecule with two adjacent hydrogen atoms replaced by a lactone-like chain , forming a second six-membered heterocycle that shares two carbons with the benzene ring. It can be placed in the benzopyrone chemical class and considered as a lactone. Coumarin is a colorless crystalline solid with a sweet odor resembling the scent of vanilla and a bitter taste.
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Schwarzites are negatively curved carbon surfaces originally proposed by decorating triply periodic minimal surfaces with carbon atoms. The geometric topology of the structure is determined by the presence of ring defects, such as heptagons and octagons, to graphene's hexagonal lattice. (Negative curvature bends surfaces outwards like a saddle rather than bending inwards like a sphere.) Recent work has proposed Zeolite-templated carbons (ZTCs) may be Schwarzites. The name, ZTC, derives from their origin inside the pores of zeolites, crystalline silicon dioxide minerals.
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The polymer is created from esterification reactions with fatty acids and contains 14 to 16 carbons per polyglycerol moiety. Sucrose monoesters are derived from the esterification of sucrose with a fatty acid ester or a fatty acid and it ideally should have a fatty acyl group ranging from 14 to 18 carbon atoms. Lastly, phospholipid such as lecithin, cephalin, and sphingomyelin can also be used as effective emulsifiers. In addition, some of the emulsifier act as a lubricant during the extrusion process.
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Berg's postgraduate studies involved the use of radioisotope tracers to study intermediary metabolism. This resulted in the understanding of how foodstuffs are converted to cellular materials, through the use of isotopic carbons or heavy nitrogen atoms. Paul Berg's doctorate paper is now known as the conversion of formic acid, formaldehyde and methanol to fully reduced states of methyl groups in methionine. He was also one of the first to demonstrate that folic acid and B12 cofactors had roles in the processes mentioned.
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Fusel alcohols or fuselol, also sometimes called fusel oils in Europe, are mixtures of several higher alcohols (those with more than 2 carbons, chiefly amyl alcohol) produced as a by-product of alcoholic fermentation. The word Fusel is German for "bad liquor". Whether fusel alcohol contributes to hangover symptoms is a matter of scientific debate. A Japanese study in 2003 concluded: "the fusel oil in whisky had no effect on the ethanol-induced emetic response" in the Asian house shrew.
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These carbon chains usually do not possess a large number of double bonds. The second type of B. braunii is green and produces even-numbered carbon chains that are between 34 and 38 carbons long, with many double bonds present. While the cause of this difference is not well-studied, the two different algae can be used for discrete purposes. Dr. Calvin began his studies of hydrocarbon plants in 1977 by looking at yields of Euphorbia lathyris over two years.
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Nucleic acids, phospholipids, and amino acids are important cell building- blocks, which are greatly needed by highly proliferating cells, such as tumor cells. Due to the key position of pyruvate kinase within glycolysis, the tetramer:dimer ratio of PKM2 determines whether glucose carbons are converted to pyruvate and lactate under the production of energy (tetrameric form) or channelled into synthetic processes (dimeric form). In tumor cells, PKM2 is mainly in the dimeric form and has, therefore, been termed Tumor M2-PK.
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Structure of [14.22]adz Structure of hexamethylenetetramine Adamanzanes (abbreviated Adz) are compounds containing four nitrogen atoms linked by carbons (analogous to adamantane with nitrogen at the branched position). Often coordinated to a central ligand, the nitrogens occupy the vertices of a tetrahedron, with potentially four faces and six edges, with the carbon chains running approximately along the edges. They can have a "bowl" or "cage" structure, with varying lengths or omission of the carbon chains. In the nomenclature of Springborg et al.
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Naringenin has the skeleton structure of a flavanone with three hydroxy groups at the 4', 5, and 7 carbons. It may be found both in the aglycol form, naringenin, or in its glycosidic form, naringin, which has the addition of the disaccharide neohesperidose attached via a glycosidic linkage at carbon 7. Like the majority of flavanones, naringenin has a single chiral center at carbon 2, although the optical purity is variable. Racemization of S(-)-naringenin has been shown to occur fairly quickly.
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Protein structure reconstruction refers to constructing an atomic-resolution model of a protein structure from incomplete coarse-grained representations like, for example, protein contact maps, positions of alpha carbon atoms only or backbone chain atoms only. There are many computational tools for protein structure reconstruction that are usually focused on specific reconstruction tasks which include: backbone reconstruction from alpha carbons, side-chains reconstruction from backbone chain atoms, hydrogen atoms reconstruction from heavy atoms positions and recovery of protein structure from contact maps.
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Figure 4. Modular arrangement of PKS enzyme complex for Callystatin A Although the biosynthetic pathway of callystatin A has not been explicitly described, its polyketide structure indicates that the pathway must involve the polyketide synthase (PKS) enzyme complex. In general, in a modular fashion, an acetate starting unit in the loading module is extended by two carbons each time by the ketosynthase (KS) domain. The acyl groups are loaded onto the acyl carrier protein (ACP) with the help of the acyltransferase (AT) domain.
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A lactone is eventually formed and the ring is opened by the use of a Grignard reagent to give (+)-trans-chrysanthemic acid. The preparation of (S)-pyrethrolone is essentially a 2 step synthesis. The starting material (S)-4-hydroxy-3-methyl-2-(2-propynyl)-2-cyclopenten-1-one (7) is also commercially available as the alcohol moiety of ETOC©. Tetrakis(triphenylphosphine)palladium(0), copper(I) iodide, triethylamine, and vinyl bromide are added to (7) to add two more carbons and form (8).
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The SSSR model has been criticised by OpenEye, OEChem - C++ Manual, Version 1.5.1, OpenEye Scientific Software, Santa Fe, New Mexico who, in their implementation of SMARTS, use `R` to denote the number of ring bonds for an atom. The two carbon atoms in the ring fusion match `[cR3]` and the other carbons match `[cR2]` in the OpenEye implementation of SMARTS. Used without a number, `R` specifies an atom in a ring in both implementations, for example `[CR]` (aliphatic carbon atom in ring).
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Sodium myreth sulfate is very similar to sodium laureth sulfate; the only difference is two more carbons in the fatty alcohol portion of the hydrophobic tail. It is manufactured by ethoxylation (hence the "eth" in "myreth") of myristyl alcohol. Subsequently, the terminal OH group is converted to the sulfate by treatment with chlorosulfuric acid.Eduard Smulders, Wolfgang von Rybinski, Eric Sung, Wilfried Rähse, Josef Steber, Frederike Wiebel, Anette Nordskog “Laundry Detergents” in Ullmann's Encyclopedia of Industrial Chemistry 2007, Wiley-VCH, Weinheim. .
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Peptidomimetic foldamers often break the previously mentioned definition of foldamers as they often adopt helical structures. They represent a major landmark of foldamer research due to their design and capabilities.Anslyn and Dougherty, Modern Physical Organic Chemistry, University Science Books, 2006, The largest groups of peptidomimetic consist of β – peptides, γ – peptides and δ – peptides, and the possible monomeric combinations. The amino acids of these peptides only differ by one (β), two (γ) or three (δ) methylene carbons, yet the structural changes were profound.
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Fluoropolymers are similar in many regards with smaller molecules; adding fluorine to a polymer affects the properties in the same manner as in small molecules (increasing chemical stability, melting point, reducing flammability, solubility, etc.). Each fluoropolymer has own characteristic properties, though. The simplest fluoroplastic is polytetrafluoroethylene (PTFE, DuPont brand Teflon), which is a simple linear chain polymer with the repeating structural unit:–CF2–. PTFE has a backbone of carbons single bonded in a long chain, with all side bonds to fluorines.
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Their current and permanent drummer (since 2015) is Ryan McHale (New York), and their former drummer was Dave Rahn from Atlanta (Gentleman Jesse & His Men, Carbons) who also played the drums on all Baby Shakes recordings prior to 2016. Their drummer during their February 2009 Japanese tour was Travis Ramin (Nikki Corvette, Fevers) and Shingo Nishimaru was their drummer during their 2009 European tour. Bio taken from www.babyshakes.com: Baby Shakes are a rock n’ roll-punk band from New York City.
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They are a two-car household, and each vehicle emits 10 tons of CO2 over the course of a year. The power used to run the Carbons' home and all its comforts translates into a similar amount. Much of the family's plentiful food supply will have crossed continents by the time it reaches their kitchen, and will have added a tenth to their annual emissions. Yet more are produced by their refuse: buried in a landfill, it heats up as it decomposes and releases greenhouse gases.
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Fullerenes are stable, but not totally unreactive. The sp2-hybridized carbon atoms, which are at their energy minimum in planar graphite, must be bent to form the closed sphere or tube, which produces angle strain. The characteristic reaction of fullerenes is electrophilic addition at 6,6-double bonds, which reduces angle strain by changing sp2-hybridized carbons into sp3-hybridized ones. The change in hybridized orbitals causes the bond angles to decrease from about 120° in the sp2 orbitals to about 109.5° in the sp3 orbitals.
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Another convention uses letters of the Greek alphabet in sequence, starting with the first carbon after the carboxyl. Thus carbon α (alpha) is C-2, carbon β (beta) is C-3, and so forth. Although fatty acids can be of diverse lengths, in this second convention the last carbon in the chain is always labelled as ω (omega), which is the last letter in the Greek alphabet. A third numbering convention counts the carbons from that end, using the labels "ω", "ω−1", "ω−2".
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However, atoms two and four are exactly equivalent - which can be shown by turning the molecule around by 180 degrees. The locant is the number of the carbon atom to which the oxygen atom is bonded. If the oxygen is bonded to the middle carbon, the locant is 3. If the oxygen is bonded to an atom on either side (adjacent to an end carbon), the locant is 2 or 4; given the choice here, where the carbons are exactly equivalent, the lower number is always chosen.
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The use of an inorganic sulfur source is quite unusual for biosynthetic reactions involving sulfur. However, dethiobiotin contains nonpolar, unactivated carbon atoms at the locations of desired C-S bond formation. The formation of the 5’-dA radical allows for hydrogen abstraction of the unactivated carbons on DTB, leaving behind activated carbon radicals ready to be functionalized. By nature, radical chemistry allows for chain reactions because radicals are easily quenched through C-H bond formation, resulting in another radical on the atom the hydrogen came from.
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Triglycerides, stored in adipose tissue, are a major form of energy storage both in animals and plants. They are a major source of energy because carbohydrates are fully reduced structures. In comparison to glycogen which would contribute only half of the energy per its pure mass, triglyceride carbons are all bonded to hydrogens, unlike in carbohydrates. The adipocyte, or fat cell, is designed for continuous synthesis and breakdown of triglycerides in animals, with breakdown controlled mainly by the activation of hormone-sensitive enzyme lipase.
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To preserve valence 4 for carbons, the opposite corners of the hexagon are connected by single bonds.Claus, Adolph K.L. (1867) "Theoretische Betrachtungen und deren Anwendungen zur Systematik der organischen Chemie" (Theoretical considerations and their applications to the classification scheme of organic chemistry), Berichte über die Verhandlungen der Naturforschenden Gesellschaft zu Freiburg im Breisgau (Reports of the Proceedings of the Scientific Society of Freiburg in Breisgau), 4 : 116-381. In the section Aromatischen Verbindungen (aromatic compounds), pp. 315-347, Claus presents Kekulé's hypothetical structure for benzene (p.
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Cited in . The nucleus of black carbon particles produced by the biomass remains aromatic even after thousands of years and presents the spectral characteristics of fresh charcoal. Around that nucleus and on the surface of the black carbon particles are higher proportions of forms of carboxylic and phenolic carbons spatially and structurally distinct from the particle's nucleus. Analysis of the groups of molecules provides evidences both for the oxidation of the black carbon particle itself, as well as for the adsorption of non-black carbon.
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Figure 7: Acetolysis of a single enantiomer of 2-exo-norbornyl brosylate leads to a racemic mixture of 2-exo-norbornyl acetate. When a single enantiomer of 2-exo- norbornyl brosylate undergoes acetolysis, no optical activity is seen in the resulting 2-exo-norbornyl acetate (see Figure 7). Under the non-classical description of the 2-norbornyl cation, the plane of symmetry present (running through carbons 4, 5, and 6) allow equal access to both enantiomers of the product, resulting in the observed racemic mixture.
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Since the π bondings will make cis/trans isomers, the unsaturated hydrocarbon isomers will appear differently due to different J-coupling effect. Cis vicinal hydrogens will have coupling constants in the range of 6–14 Hz, whereas the trans will have coupling constants of 11–18 Hz. In 13C NMR spectroscopy, compared to the saturated hydrocarbons, the double and triple bonds also deshiled the carbons, making them have low field shift. C=C double bonds usually have chemical shift of about 100–170 ppm.
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"Bidirectional Reaction Steps in Metabolic Networks: Modeling and Simulation of Carbon Isotope Labeling Experiments". Biotechnol. Bioeng. 55(1):101-117 The organism is fed a mixture that contains molecules where specific carbons are engineered to be carbon-13 atoms, instead of carbon-12. After these molecules are used in the network, downstream metabolites also become labeled with carbon-13, as they incorporate those atoms in their structures. The specific labeling pattern of the various metabolites is determined by the reaction fluxes in the network.
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Adapted from Neighboring groups surround the alkyne can enhance reaction kinetics by interacting with the intermediate via nonclassical approaches like intramolecular interactions. An alkyne that is adjacent to a tertiary alcohol formas a four-membered cyclic vinyl cation intermediate in which the oxygen of the hydroxyl group bridges two carbons across two bonds. Likewise, a five-membered chloronium ring intermediate is formed from 5-chloro substituted 1-pentynes. An unusually shifted product is formed because the intermediate undergoes heterolysis at the C5-Cl position.
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In the solvolysis of methyl substituted cyclohexenyl triflate, the rearrangement and non-rearranged product are formed in almost equal amounts, with a small preference to the rearrangement product because of its linear structure. However, it must be noted that there is some strain in the methylenesyclopentane rearrangement product. Lastly, halogens could also move into and stabilize a vinyl cation system. In the reaction of 5-chloropentyne with trifluoroacetic acid, there is simultaneous protonation and 1,4-shift of chlorine that forms a bridge cyclic structure across four carbons.
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The approximate computed distances are C–C 0.211 nm, C–H 0.124 nm (bridging), 0.107 nm (bottom) and 0.108 nm (top); the C–H–C angle at the bridge is about 116 degrees, the H–C–H angles are 116 degrees (bottom-bottom) and 114 degrees (bottom-top). However, there are other configurations with near-minimum energy, including one where the two subgroups are slightly staggered (with Cs symmetry), another where one of the carbons of a ion is loosely bound to an molecule 0.250 nm away.
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Glycolaldehyde is the only diose A diose is a monosaccharide containing two carbon atoms. Because the general chemical formula of an unmodified monosaccharide is (C·H2O)n, where n is three or greater, it does not meet the formal definition of a monosaccharide. However, since it does fit the formula (C·H2O)n, it is sometimes thought of as the most basic sugar. There is only one possible diose, glycolaldehyde (2-hydroxyethanal), which is an aldodiose (a ketodiose is not possible since there are only two carbons).
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When ninhydrin reacts with amino acids, the reaction also releases CO2. The carbon in this CO2 originates from the carboxyl carbon of the amino acid. This reaction has been used to release the carboxyl carbons of bone collagen from ancient bones for stable isotope analysis in order to help reconstruct the palaeodiet of cave bears. Release of the carboxyl carbon (via ninhydrin) from amino acids recovered from soil that has been treated with a labeled substrate demonstrates assimilation of that substrate into microbial protein.
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Alkanes have a high ionization energy, and the molecular ion is usually weak. The fragmentation pattern can be difficult to interpret, but, in the case of branched chain alkanes, the carbon chain is preferentially cleaved at tertiary or quaternary carbons due to the relative stability of the resulting free radicals. The fragment resulting from the loss of a single methyl group (M − 15) is often absent, and other fragments are often spaced by intervals of fourteen mass units, corresponding to sequential loss of CH2 groups.
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The band gap of carbon nanobuds is not constant, it can change through the size of the fullerene group. The attachment of C60 added to the armchair orientation of the SWCNT opens up the band gap. On the other hand, adding it to a semiconducting SWCNT could introduce impurity states to the band gap, which would reduce the band gap. The band gap of CNBs can also be modified by changing the density of the carbons of the C60 attached to the sidewall of the SWCNT.
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Tyramine is broken down by MAO-A and MAO-B, therefore inhibiting this action may result in its excessive build-up, so diet must be monitored for tyramine intake. MAO-B inhibition reduces the breakdown mainly of dopamine and phenethylamine so there are no dietary restrictions associated with this. MAO-B would also metabolize tyramine, as the only differences between dopamine, phenethylamine, and tyramine are two phenylhydroxyl groups on carbons 3 and 4. The 4-OH would not be a steric hindrance to MAO-B on tyramine.
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Over the three decades after the discovery of erythromycin A and its activity as an antimicrobial, many attempts were made to synthesize it in the laboratory. The presence of 10 stereogenic carbons and several points of distinct substitution has made the total synthesis of erythromycin A a formidable task. Complete syntheses of erythromycins’ related structures and precursors such as 6-deoxyerythronolide B have been accomplished, giving way to possible syntheses of different erythromycins and other macrolide antimicrobials. Woodward successfully completed the synthesis of erythromycin A.
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Accounting for these cases, the IUPAC recommends the more general E-Z notation, instead of the cis and trans prefixes. This notation considers the group with highest CIP priority in each of the two carbons. If these two groups are on opposite sides of the double bond's plane, the configuration is labeled E (from the German entgegen meaning "opposite"); if they are on the same side, it is labeled Z (from german zusammen, "together"). This labeling may be taught with mnemonic "Z means 'on ze zame zide'".
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For example, in pyridine, the five sp2-hybridized carbons each have a p-orbital that is perpendicular to the plane of the ring, and each of these p-orbitals contains one π-electron. Additionally, the nitrogen atom is also sp2-hybridized and has one electron in a p-orbital, which adds up to 6 p-electrons, thus making pyridine aromatic. The lone pair on the nitrogen is not part of the aromatic π system. Pyrrole and imidazole are both five membered aromatic rings that contain heteroatoms.
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He noticed that not only the number but the position of double bonds is involved in oxidation susceptibility. For instance, linolenic acid with two bis-allylic positions (at the carbons no. 11 and 14 between the double bonds Δ9, Δ12 and Δ15) is more prone to autoxidation than linoleic acid exhibiting one bis-allylic position (at C-11 between Δ9 and Δ12). Therefore Knothe introduced alternative indices termed allylic position and bis-allylic position equivalents (APE and BAPE), which could be obtained by chromatographic analysis.
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Pentenoic acid is any of five mono-carboxylic acids whose molecule has an unbranched chain of five carbons conected by three single bonds and one double bond. That is, any compound with one of the formulas HO(O=)C–CH=CH–– (2-pentenoic), HO(O=)C––CH=CH– (3-pentenoic), or HO(O=)C–––CH= (4-pentenoic). In the IUPAC-recommended nomeclature, these acids are called pent-2-enoic, pent-3-enoic, and pent-4-enoic, respectively. All these compounds have the empirical formula .
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Horowitz and Geissman's first example demonstrates a possible thermodynamic sink to couple with the cationic 2-aza-Cope rearrangement, where the product is biased by the phenyl substituent through aryl conjugation, then captured by hydrolysis of the iminium. Other methods of biasing a product include using substituents which are more stable on substituted carbons, releasing ring strain (for instance, by pairing the rearrangement with cyclopropane opening), intramolecular trapping (pictured), and pairing the rearrangement with the Mannich cyclization. The iminium is trapped by the intramolecular nucleophile.
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On average, each vehicle emits about 250 pounds of carbon monoxides, 18.32 pounds of nitrogen oxides, 29 pounds of hydro-carbons and 9,737 pounds of carbon dioxide every year. These gases emitted by vehicles are harmful to humans both directly and indirectly. The biggest and most widely known issue caused by vehicles is due to the carbon dioxide they produce. Carbon dioxide is known as a greenhouse gas because they ascend into the atmosphere and act as a blanket within our atmosphere causing the "Greenhouse effect".
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Gasoline is the most widely used liquid fuel. Gasoline, as it is known in United States and Canada, or petrol virtually everywhere else, is made of hydrocarbon molecules (compounds that contain hydrogen and carbon only) forming aliphatic compounds, or chains of carbons with hydrogen atoms attached. However, many aromatic compounds (carbon chains forming rings) such as benzene are found naturally in gasoline and cause the health risks associated with prolonged exposure to the fuel. Production of gasoline is achieved by distillation of crude oil.
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This full proton decoupling eliminates all coupling with H atoms and thus splitting due to H atoms in natural isotopic abundance compounds. Since coupling between other carbons in natural isotopic abundance samples is negligible, signals in fully proton decoupled 13C spectra in hydrocarbons and most signals from other organic compounds are single peaks. This way, the number of equivalent sets of carbon atoms in a chemical structure can be counted by counting singlet peaks, which in 13C spectra tend to be very narrow (thin).
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Such materials combine high hydrophobicity and chemical stability with electrical and thermal conductivity and can be used as electrode material for super capacitors. Sulfonic acid functional groups can be attached to activated carbon to give "starbons" which can be used to selectively catalyse the esterification of fatty acids. Formation of such activated carbons from halogenated precursors gives a more effective catalyst which is thought to be a result of remaining halogens improving stability. It is reported about synthesis of activated carbon with chemically grafted superacid sites –CF2SO3H.
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Policosanols are very long chain alcohols with carbon backbones ranging from 24 to 34 carbons. The first policosanol supplements were produced by Dalmer Laboratories in Cuba; studies conducted and published by that group have found that policosanol is safe and effective as a lipid-lowering agent. However these studies were small, and efforts by groups outside of Cuba have failed to replicate these results. A meta-analysis in 2005 concluded that human policosanol consumption is safe and well tolerated and is effective at lowering the blood cholesterol.
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Disaccharides consist of two monosaccharides and may be either reducing or nonreducing. Even a reducing disaccharide will only have one reducing end, as disaccharides are held together by glycosidic bonds, which consist of at least one anomeric carbon. With one anomeric carbon unable to convert to the open-chain form, only the free anomeric carbon is available to reduce another compound, and it is called the reducing end of the disaccharide. A nonreducing disaccharide is that which has both anomeric carbons tied up in the glycosidic bond.
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20α,22R-Dihydroxycholesterol, or (3β)-cholest-5-ene-3,20,22-triol is an endogenous, metabolic intermediate in the biosynthesis of the steroid hormones from cholesterol. Cholesterol ((3β)-cholest-5-en-3-ol) is hydroxylated by cholesterol side-chain cleavage enzyme (P450scc) to form 22R-hydroxycholesterol, which is subsequently hydroxylated again by P450scc to form 20α,22R-dihydroxycholesterol, and finally the bond between carbons 20 and 22 is cleaved by P450scc to form pregnenolone ((3β)-3-hydroxypregn-5-en-20-one), the precursor to the steroid hormones.
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150px A staffane or [n]staffane is an organic compound, a polycyclic hydrocarbon with molecular structure H-[-C≡(-CH2-)3≡C-]n-H, for some integer n ≥ 1. The chemical formula is therefore C5nH6n+2 Staffanes were first obtained in 1988 by P. Kazynski and J. Michl, by spontaneous polymerization of [1.1.1]-propellane C5H6 or C2(=CH2)3. In the reaction, the axial C-C bond of the propellane (the "bridge") is broken, creating a free bond on each of the two axial carbons (the "bridgeheads").
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Non-immobilized BSA was rinsed out with PBS and CLEN solution was poured on the spots, unimmobilized CLEN was removed through PBS rinse. An alkanethiol-SAM was prepared in order to simultaneously measure the concentration of horseradish peroxidase (Px), Human Immunoglobulin E (IgE), Human choriogonadotropin (hCG) and Human immunoglobulin G (IgG), through SPR. The alkanethiols made of carbon chains composed by 11 and 16 carbons were self-assembled on the sensor chip. The antibodies were attached to the C16 alkanethiol, which had a terminal carboxylic group.
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The carbon source for the CVD of VANTAs is most commonly a carbon gas such as methane, ethylene, acetylene, benzene, xylene, or carbon monoxide. Other examples of carbon precursors include cyclohexane, fullerene, methanol, and ethanol. The pyrolysis of these gases into carbon atoms varies based on the decomposition rate at growth temperatures, the carbon content of the gas molecules, and the growth catalyst. Linear hydrocarbons such as methane, ethylene, acetylene, thermally decompose into atomic carbons or linear dimers/trimers of carbon, and generally produce straight and hollow CNTs.
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The tert- butyl functional group is a unique moiety in this compound: two of the three carbons were found to originate from the amino acid valine, which contains an isopropyl alkyl side chain. This was determined by deuteration of valine supplied in the media, where mass spectroscopy identified mass/charge ratio reflecting the replacement of 8 hydrogens with deuterium in valine. The final alkyl group in the tert-butyl group was found to be from methionine, likely from S-adenylation. The order in which these precursor units are synthesized has not been confirmed.
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A block of silica aerogel in hand Carbon aerogel is a highly porous, synthetic, ultralight material derived from an organic gel in which the liquid component of the gel has been replaced with a gas. Aerogel electrodes are made via pyrolysis of resorcinol-formaldehyde aerogels and are more conductive than most activated carbons. They enable thin and mechanically stable electrodes with a thickness in the range of several hundred micrometres (µm) and with uniform pore size. Aerogel electrodes also provide mechanical and vibration stability for supercapacitors used in high-vibration environments.
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The electrolyte determines the capacitor's characteristics: its operating voltage, temperature range, ESR and capacitance. With the same activated carbon electrode an aqueous electrolyte achieves capacitance values of 160 F/g, while an organic electrolyte achieves only 100 F/g.P. Simon, A. Burke, Nanostructured Carbons: Double-Layer Capacitance and More The electrolyte must be chemically inert and not chemically attack the other materials in the capacitor to ensure long time stable behavior of the capacitor's electrical parameters. The electrolyte's viscosity must be low enough to wet the porous, sponge-like structure of the electrodes.
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Robert Thornton Morrison and Robert Neilson Boyd (1998): Organic Chemistry, 6th edition. The conventional numbering of the carbons in the closed form is the same as in the open-chain form. If the sugar is a aldohexose, with the carbonyl in position 1, the reaction may involve the hydroxyl on carbon 4 or carbon 5, creating a hemiacetal with five- or six- member ring, respectively. If the sugar is a 2-ketohexose, it can only involve the hydroxyl in carbon 5, and will create a hemiketal with a five-member ring.
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Despite anisomycin's wide usage as a protein synthesis inhibitor, there have been a lot of studies centered on the biosynthesis of anisomycin. One study by Butler in 1974 proposed possible precursors to this natural product. Fermentation of Streptomyces with labeled amino acids was followed by a degradation of the radioactive anisomycin and deacetylanisomycin products to determine the locations of the labeled carbons. Although its pyrrolidine-based structure suggests that it is derived from proline, the results from the experiments indicated that tyrosine, glycine, methionine, and acetate are the primary precursors for the biosynthesis of anisomycin.
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General chemical structure of a phosphatidyl glycerol where R1 and R2 are fatty acid side chains Phosphatidylglycerol is a glycerophospholipid found in pulmonary surfactant and in the plasma membrane where it directly activates lipid-gated_ion_channels. The general structure of phosphatidylglycerol consists of a L-glycerol 3-phosphate backbone ester-bonded to either saturated or unsaturated fatty acids on carbons 1 and 2. The head group substituent glycerol is bonded through a phosphomonoester. It is the precursor of surfactant and its presence (>0.3) in the amniotic fluid of the newborn indicates fetal lung maturity.
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Although they may be structurally similar, they all have different functions. Beta-gal is inhibited by L-ribose, non-competitive inhibitor iodine, and competitive inhibitors phenylthyl thio-beta-D-galactoside (PETG), D-galactonolactone, isopropyl thio-beta-D-galactoside (IPTG), and galactose. β-galactosidase is important for organisms as it is a key provider in the production of energy and a source of carbons through the break down of lactose to galactose and glucose. It is also important for the lactose intolerant community as it is responsible for making lactose-free milk and other dairy products.
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The protein FFA1 is activated by medium to long chain fatty acids. FFA1 is most strongly activated by eicosatrienoic acid (20:3Δ11,14,17), but has been found to be activated by fatty acids as small as 10 carbons long. For saturated fatty acids the level of activation is dependent on the length of the carbon chain, which is not true for unsaturated fatty acids. It has been found that three hydrophilic residues (arginine-183, asparagine-244, and arginine-258) anchor the carboxylate group of a fatty acid, which activates FFA1.
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As an example, under strong basic conditions (e.g. sodium hydroxide), hexane-2,5-dione (compound A in Figure 1) can cyclize via intramolecular aldol reaction to form the 3-methylcyclopent-2-en-1-one (compound B). The mechanism of the intramolecular aldol reaction involves formation of a key enolate intermediate followed by an intramolecular nucleophilic addition process. First, hydroxide abstracts the α-hydrogen on a terminal carbon to form the enolate. Next, a nucleophilic attack of the enolate on the other keto group forms a new carbon-carbon bond (red) between carbons 2 and 6.
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The chirality of the product of a Sharpless epoxidation is sometimes predicted with the following mnemonic. A rectangle is drawn around the double bond in the same plane as the carbons of the double bond (the xy- plane), with the allylic alcohol in the bottom right corner and the other substituents in their appropriate corners. In this orientation, the (−) diester tartrate preferentially interacts with the top half of the molecule, and the (+) diester tartrate preferentially interacts with the bottom half of the molecule. This model seems to be valid despite substitution on the olefin.
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Frequently, porous adsorbents with large surface areas, but only weak adsorption sites, lack sufficient capacity for CO2 under realistic conditions. To increase low pressure CO2 adsorption capacity, adding amine functional groups to highly porous materials has been reported to result in new adsorbents with higher capacities. This strategy has been analyzed for polymers, silicas, activated carbons and metal-organic frameworks. Amine impregnated solids utilize the well-established acid-base chemistry of CO2 with amines, but dilute the amines by containing them within the pores of solids rather than as H2O solutions.
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Formerly the name "carbohydrate" was used in chemistry for any compound with the formula Cm (H2O)n. Following this definition, some chemists considered formaldehyde (CH2O) to be the simplest carbohydrate, while others claimed that title for glycolaldehyde. Today, the term is generally understood in the biochemistry sense, which excludes compounds with only one or two carbons and includes many biological carbohydrates which deviate from this formula. For example, while the above representative formulas would seem to capture the commonly known carbohydrates, ubiquitous and abundant carbohydrates often deviate from this.
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This is the pKa for protonated caffeine, given as a range of values included in Caffeine does not contain any stereogenic centers and hence is classified as an achiral molecule. The xanthine core of caffeine contains two fused rings, a pyrimidinedione and imidazole. The pyrimidinedione in turn contains two amide functional groups that exist predominantly in a zwitterionic resonance the location from which the nitrogen atoms are double bonded to their adjacent amide carbons atoms. Hence all six of the atoms within the pyrimidinedione ring system are sp2 hybridized and planar.
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However, most believed that what was governing preferential product formation involved the migratory aptitudes of competing carbons and/or steric control. Migratory aptitude made reference to the possibility that the preferred product of the reaction was the result of an initial stability of one carbon migrating in preference to another. This possibility was more the belief and subject of research of earlier scientists, including Marc Tiffeneau himself. However, in the early 1960s, more and more scientists were starting to think that steric factors were the driving force behind the selectivity for this reaction.
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Copper naphthenate is the copper salt of naphthenic acid. Naphthenic acid is a term commonly used in the petroleum industry to collectively refer to all of the carboxylic acids naturally occurring in crude oil. Naphthenic acids are primarily cycloaliphatic carboxylic acids with 10 to 24 or more carbons, although substantial quantities of non-cyclic, aromatic and heteroatom- containing carboxylic acids are also present. Copper naphthenate is most widely used in wood preservation and for protecting other cellulosic materials such as textiles and cordage from damage by decay fungi and insects.
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Cyclopentadienyl magnesium bromide is a chemical compound with the molecular formula . The molecule consists of a magnesium atom bonded to a bromine atom and a cyclopentadienyl group, a ring of five carbons each with one hydrogen atom. The compound is a Grignard reagent, a type of organometallic compound that features a magnesium atom bonded to a halogen atom and to a carbon atom of some organic functional group. This compound is of historic importance as the starting material for the first published synthesis of ferrocene by Peter Pauson and Thomas J. Kealy in 1951.
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Some chemists have also considered the 2-norbornyl cation to be best represented by the nortricylconium ion, a C-symmetric protonated nortricyclene. This depiction was first invoked to partially explain results of a C isotope scrambling experiment. The molecular orbital representation of this structure involves an in-phase interaction between sp-hybridized orbitals from carbons 1, 2 and 6 and the 1s atomic orbital on a shared hydrogen atom (see Figure 5). Figure 5: (Colors added for clarity.) (a) Nortricyclene; (b) Nortricyclonium ion (protonated nortricyclene); (c,d) Molecular orbitals for nortricyclonium ion.
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It was also observed that the 2-exo-substituted norbornanes reacted 350 times faster than the corresponding endo isomers. Anchimeric assistance of the sigma bond between carbons 1 and 6 was rationalized as the explanation for this kinetic effect. Importantly, the invoked anchimeric assistance led many chemists to postulate that the energetic stability of the 2-norbornyl cation was directly due to the symmetric, bridged structure invoked in the non-classical explanation. However, some other authors offered alternative explanations for the high stability without invoking a non-classical structure.
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The chair and twist-boat are energy minima and are therefore conformers, while the half-chair and the boat are transition states and represent energy maxima. The idea that the chair conformation is the most stable structure for cyclohexane was first proposed as early as 1890 by Hermann Sachse, but only gained widespread acceptance much later. The new conformation puts the carbons at an angle of 109.5°. Half of the hydrogens are in the plane of the ring (equatorial) while the other half are perpendicular to the plane (axial).
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Assuming the reaction happens suprafacially, the shift results with the HOMO of butadiene on the 4 carbons that are not involved in the sigma bond of the product. Since the pi system changed from the LUMO to the HOMO, this reaction is allowed (though it would not be allowed if the pi system went from LUMO to LUMO). To explain why the reaction happens suprafacially, first notice that the terminal orbitals are in the same phase. For there to be a constructive sigma bond formed after the shift, the reaction would have to be suprafacial.
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Left: 6,4-dimer. Right: cyclobutane dimer A cyclobutane pyrimidine dimer (CPD) contains a four membered ring arising from the coupling of the two double-bonded carbons of each of the pyrimidines. Such dimers interfere with base pairing during DNA replication, leading to mutations. A 6–4 photoproduct (6–4 pyrimidine–pyrimidone or 6–4 pyrimidine–pyrimidinone) is an alternate dimer consisting of a single covalent bond between the carbon at the 6 position of one ring and carbon at the 4 position of the ring on the next base.
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Dimethyl imidazol-2-ylidene, a stable dicarbene with little steric hindrance (external viewer) The stability of Arduengo carbenes was initially attributed to the bulky N-adamantyl substituents, which prevents the carbene from dimerising due to steric hindrance. Replacement of the N-adamantyl groups with methyl groups also affords stable NHCs. Thus, imidazole-2-ylidenes are thermodynamically stable. It had been also conjectured that the double bond between carbons 4 and 5 of the imidazolium ring backbone, which gave aromatic character to that system, was important for the carbene's stability.
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Activated carbons are highly porous amorphous carbon materials with high apparent surface area. Hydrogen physisorption can be increased in these materials by increasing the apparent surface area and optimizing pore diameter to around 7 Å. These materials are of particular interest due to the fact that they can be made from waste materials, such as cigarette butts which have shown great potential as precursor materials for high-capacity hydrogen storage materials. Graphene can store hydrogen efficiently. The H2 adds to the double bonds giving graphane. The hydrogen is released upon heating to 450 °C.
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's orbit is similar to that of , indicating that they may have both been thrown onto the orbit by the same body, or that they may have been the same object (single or binary) at one point. 's visible spectrum is very different from that of 90377 Sedna. The value of its spectral slope suggests that the surface of this object can have pure methane ices (like in the case of Pluto) and highly processed carbons, including some amorphous silicates. Its spectral slope is similar to that of .
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Protein structures have to be represented in some coordinate-independent space to make them comparable. This is typically achieved by constructing a sequence-to-sequence matrix or series of matrices that encompass comparative metrics: rather than absolute distances relative to a fixed coordinate space. An intuitive representation is the distance matrix, which is a two-dimensional matrix containing all pairwise distances between some subset of the atoms in each structure (such as the alpha carbons). The matrix increases in dimensionality as the number of structures to be simultaneously aligned increases.
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For example in a molecule AX3E2, the atom A has a steric number of 5. When the substituent (X) atoms are not all the same, the geometry is still approximately valid, but the bond angles may be slightly different from the ones where all the outside atoms are the same. For example, the double-bond carbons in alkenes like C2H4 are AX3E0, but the bond angles are not all exactly 120°. Likewise, SOCl2 is AX3E1, but because the X substituents are not identical, the X–A–X angles are not all equal.
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This regiochemistry follows from the reaction mechanism, which favors formation of the most stable carbon radical intermediate (relative stability: 3° > 2° > 1°> methyl). The mechanism for this reaction is similar to a chain reaction such as free radical halogenation in which the peroxide promotes the formation of the bromide radical. Therefore, in the presence of peroxides, HBr adds so that the bromine atom is added to the carbon bearing the most numerous hydrogen substituents and hydrogen atoms will add to carbons bearing fewest hydrogen substituents. However, this process is restricted to addition of HBr.
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Two different types of C-H-C bonding are recognized. The first is an "open" type, entailing linear geometry and negligible bonding between the terminal carbon atoms, while the second is the "closed" type, with triangular geometry allowing bonding interaction between terminal carbons. The relationship between these two types of 3-center 2-electron bonding can be shown through a molecular orbital diagram. Because of the additional overlap between the orbitals, the bonding orbital for the "closed" type is pushed lower in energy relative to the "open" type.
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A number of individuals with MCADD may remain completely asymptomatic, provided they never encounter a situation that sufficiently stresses their metabolism. With the advent of expanded newborn screening, some mothers have been identified with MCADD after their infants had positive newborn screens for low carnitine levels. The enzyme MCAD is responsible for the dehydrogenation step of fatty acids with chain lengths between 6 and 12 carbons as they undergo beta-oxidation in the mitochondria. Fatty acid beta-oxidation provides energy after the body has used up its stores of glucose and glycogen.
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Certain N-substituted azirines with electron withdrawing groups on both carbons form azomethine ylides in an electrocyclic thermal or photochemical ring-opening reaction. These ylides can be trapped with a suitable dipolarophile in a 1,3-dipolar cycloaddition. :Aziridine ring opening When the N-substituent is an electron-withdrawing group such as a tosyl group, the carbon-nitrogen bond breaks, forming another zwitterion :2-phenyl-N-tosyl-aziridine cycloadditions This reaction type requires a Lewis acid catalyst such as boron trifluoride. In this way 2-phenyl-N-tosylaziridine reacts with alkynes, nitriles, ketones and alkenes.
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The Dowd–Beckwith ring-expansion reaction is an organic reaction in which a cyclic β-keto ester is expanded by up to 4 carbons in a free radical ring expansion reaction through an α-alkylhalo substituent. The radical initiator system is based on AIBN and tributyltin hydride. The cyclic β-keto ester can be obtained through a Dieckmann condensation. The original reaction consisted of a nucleophilic aliphatic substitution of the enolate of ethyl cyclohexanone-2-carboxylate with 1,4-diiodobutane and sodium hydride followed by ring expansion to ethyl cyclodecanone-6-carboxylate.
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C15) as the cyclisation of farnesyl pyrophosphate cannot produce two dimethylate carbons that are separated by a single carbon nor would this be consistent with the natural occurrence of similar compounds with different keto-aryl side-chains in the members of the Myrtaceae (eg. flavesone, papuanone, isoleptospermone and grandiflorone). Phloroglucinol is biosynthesized in a single step from malonyl-CoA and could be the intermediate, but other routes of biosynthesis may be possible, such as via isobutyryl-CoA, the result of the decarboxylative condensation of ketoisovalerate (ketone form of valine) (cf. polyketides).
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The residue of lysine-142 in the active site of transaldolase forms a Schiff base with the keto group in sedoheptulose-7-phosphate after deprotonation by another active site residue, glutamate-106. The reaction mechanism is similar to the reverse reaction catalyzed by aldolase: The bond joining carbons 3 and 4 is broken, leaving dihydroxyacetone joined to the enzyme via a Schiff base. This cleavage reaction generates the unusual aldose sugar erythrose-4-phosphate. Then transaldolase catalyzes the condensation of glyceraldehyde-3-phosphate with the Schiff base of dihydroxyacetone, yielding enzyme-bound fructose 6-phosphate.
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Both DNA and RNA have intrinsic directionality, meaning there are two distinct ends of the molecule. This property of directionality is due to the asymmetrical underlying nucleotide subunits, with a phosphate group on one side of the pentose sugar and a base on the other. The five carbons in the pentose sugar are numbered from 1' (where ' means prime) to 5'. Therefore, the phosphodiester bonds connecting the nucleotides are formed by joining the hydroxyl group of on the 3' carbon of one nucleotide to the phosphate group on the 5' carbon of another nucleotide.
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On the other hand, it catalyzes the oxidation of alkanes to tertiary alcohols, amides to t-butyldioxyamides, and tertiary amines to α-(t-butyldioxyamides) using tert-butyl hydroperoxide. Using other peroxides, oxygen, and acetone, the catalyst can oxidize alcohols to aldehydes or ketones. Using dichlorotris(triphenylphosphine)ruthenium(II) the N-alkylation of amines with alcohols is also possible (see "borrowing hydrogen"). :650px RuCl2(PPh3)3 efficiently catalyzes carbon-carbon bond formation from cross couplings of alcohols through C-H activation of sp3 carbons in the presence of a Lewis acid.
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Molecular weight analysis of milk from different species showed that while milk fats from all studied species were primarily composed of long-chain fatty acids (16 and 18 carbons long), approximately 10–20% of the fatty acids in milk from horses, cows, sheep, and goats were medium-chain fatty acids. Some studies have shown that MCTs can help in the process of excess calorie burning, thus weight loss. MCTs are also seen as promoting fat oxidation and reduced food intake. MCTs have been recommended by some endurance athletes and the bodybuilding community.
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Pseudocapacitance may originate from the electrode structure, especially from the material pore size. The use of carbide-derived carbons (CDCs) or carbon nanotubes (CNTs) as electrodes provides a network of small pores formed by nanotube entanglement. These nanoporous materials have diameters in the range of <2 nm that can be referred to as intercalated pores. Solvated ions in the electrolyte are unable to enter these small pores, but de-solvated ions that have reduced their ion dimensions are able to enter, resulting in larger ionic packing density and increased charge storage.
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A naphthalene molecule can be viewed as the fusion of a pair of benzene rings. (In organic chemistry, rings are fused if they share two or more atoms.) As such, naphthalene is classified as a benzenoid polycyclic aromatic hydrocarbon (PAH). The eight carbons that are not shared by the two rings carry one hydrogen atom each. For purpose of the standard IUPAC nomenclature of derived compounds, those eight atoms are numbered 1 through 8 in sequence around the perimeter of the molecule, starting with a carbon adjacent to a shared one.
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For example, the aldohexose glucose may form a hemiacetal linkage between the hydroxyl on carbon 1 and the oxygen on carbon 4, yielding a molecule with a 5-membered ring, called glucofuranose. The same reaction can take place between carbons 1 and 5 to form a molecule with a 6-membered ring, called glucopyranose. Cyclic forms with a 7-atom ring called heptoses are rare. Two monosaccharides can be joined together by a glycosidic or ether bond into a disaccharide through a dehydration reaction during which a molecule of water is released.
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In enzymology, an alkane 1-monooxygenase () is an enzyme that catalyzes the chemical reactions :an alkane + reduced rubredoxin + O2 \rightleftharpoons a primary alcohol + oxidized rubredoxin + H2O. Alkanes of 6 to 22 carbons have been observed as substrates. This enzyme belongs to the family of oxidoreductases, specifically those acting on paired donors, with oxygen as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O2 with reduced iron-sulfur protein as one donor, and incorporation of one atom of oxygen into the other donor.
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These methods use rotamer libraries, which are collections of favorable conformations for each residue type in proteins. Rotamer libraries may contain information about the conformation, its frequency, and the standard deviations about mean dihedral angles, which can be used in sampling. Rotamer libraries are derived from structural bioinformatics or other statistical analysis of side-chain conformations in known experimental structures of proteins, such as by clustering the observed conformations for tetrahedral carbons near the staggered (60°, 180°, -60°) values. Rotamer libraries can be backbone-independent, secondary-structure- dependent, or backbone-dependent.
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Arachidonic acid (arachidonic's) has 20 carbons, is present in animal visceral fat (brain, liver, kidney, lung, spleen), and is a 5,8,11,14-tetra- unsaturated fatty acid. I caused by the decomposition of cell membrane in the phospholipid. Prostaglandin, and important as starting materials for the thromboxane, leukotriene such as are known as a series of metabolic pathway to give eicosanoids, arachidonic acid cascade are compounds. C19H31CO2H, IUPAC organization name (5Z , 8Z , 11 Z , 14Z)-icosa-5,8,11,14-tetraenoic acid, numerical representation 20: 4 (5,8,11,14), n-6, molecular weight 304.47, boiling point 169- 171 °C.
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Ethanol is a versatile solvent, miscible with water and with many organic solvents, including acetic acid, acetone, benzene, carbon tetrachloride, chloroform, diethyl ether, ethylene glycol, glycerol, nitromethane, pyridine, and toluene. Its main use as a solvent is in making tincture of iodine,cough syrups etc. It is also miscible with light aliphatic hydrocarbons, such as pentane and hexane, and with aliphatic chlorides such as trichloroethane and tetrachloroethylene. Ethanol's miscibility with water contrasts with the immiscibility of longer-chain alcohols (five or more carbon atoms), whose water miscibility decreases sharply as the number of carbons increases.
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Hand carved from mica from the Hopewell tradition Human use of mica dates back to prehistoric times. Mica was known to ancient Indian, Egyptian, Greek and Roman and Chinese civilizations, as well as the Aztec civilization of the New World. The earliest use of mica has been found in cave paintings created during the Upper Paleolithic period (40,000 BC to 10,000 BC). The first hues were red (iron oxide, hematite, or red ochre) and black (manganese dioxide, pyrolusite), though black from juniper or pine carbons has also been discovered.
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The OXER1 G protein-coupled receptor resembles the hydroxy carboxilic acid subfamily of G protein-coupled receptors, which besides GPR109A, niacin receptor 1, and niacin receptor 2 may include the recently defined receptor for 12-HETE, GPR31, not only in its amino acid sequence but also in the hydroxy-carboxylic acid nature of its cognate ligands. Naturally occurring ligands for OXER1 are long chain polyunsaturated fatty acids containing either a hydroxyl (i.e. -OH) or oxo (i.e. =O, keto) residue removed by 5 carbons from each of these acid's carboxy residue.
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The backbone of the DNA strand is made from alternating phosphate and sugar groups. The sugar in DNA is 2-deoxyribose, which is a pentose (five-carbon) sugar. The sugars are joined together by phosphate groups that form phosphodiester bonds between the third and fifth carbon atoms of adjacent sugar rings. These are known as the 3′-end (three prime end), and 5′-end (five prime end) carbons, the prime symbol being used to distinguish these carbon atoms from those of the base to which the deoxyribose forms a glycosidic bond.
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As predicted by the VSEPR model of electron pair repulsion, the molecular geometry of alkenes includes bond angles about each carbon in a double bond of about 120°. The angle may vary because of steric strain introduced by nonbonded interactions between functional groups attached to the carbons of the double bond. For example, the C–C–C bond angle in propylene is 123.9°. For bridged alkenes, Bredt's rule states that a double bond cannot occur at the bridgehead of a bridged ring system unless the rings are large enough.
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Aromatic compounds undergo electrophilic aromatic substitution and nucleophilic aromatic substitution reactions, but not electrophilic addition reactions as happens with carbon–carbon double bonds. In the presence of a magnetic field, the circulating π-electrons in an aromatic molecule produce an aromatic ring current that induces an additional magnetic field, an important effect in nuclear magnetic resonance. The NMR signal of protons in the plane of an aromatic ring are shifted substantially further down-field than those on non-aromatic sp2 carbons. This is an important way of detecting aromaticity.
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This decision sets out the rules that govern how Kyoto Parties with emission reduction commitments (so-called Annex 1 Parties) account for changes in carbon stocks in land use, land-use change and forestry. It is mandatory for Annex 1 Parties to account for changes in carbons stocks resulting from deforestation, reforestation and afforestation (B Article 3.3) and voluntary to account for emissions from forest management, cropland management, grazing land management and revegetation (B. Article 3.4). The land-use sector is critical to achieving the aim of the Paris Agreement to limit global warming to .
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The Simmons–Smith reaction is an organic cheletropic reaction involving an organozinc carbenoid that reacts with an alkene (or alkyne) to form a cyclopropane. It is named after Howard Ensign Simmons, Jr. and Ronald D. Smith. It uses a methylene free radical intermediate that is delivered to both carbons of the alkene simultaneously, therefore the configuration of the double bond is preserved in the product and the reaction is stereospecific. :594x594px Thus, cyclohexene, diiodomethane, and a zinc-copper couple (as iodomethylzinc iodide, ICH2ZnI) yield norcarane (bicyclo[4.1.0]heptane).
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This primary structure leads to folding of the protein into the secondary structure, formed by hydrogen bonding between the carbonyl oxygens and amine hydrogens in the backbone. Further interactions between residues of the individual amino acids form the protein's tertiary structure. For this reason, the primary structure of the amino acids in the polypeptide backbone is the map of the final structure of a protein, and it therefore indicates its biological function. Spatial positions of backbone atoms can be reconstructed from the positions of alpha carbons using computational tools for the backbone reconstruction.
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The bacteria use the hydrogen sulfide as energy to produce organic carbons that feed the shipworms. The process is similar to the green plants' photosynthesis to convert the carbon dioxide in the air into simple carbon compounds during photosynthesis. Scientists found that K. polythalamia cooperates with different bacteria than other shipworms which could be the reason why it evolved from consuming rotten wood to living on hydrogen sulfide in the mud. The internal organs of the shipworm have shrunk from lack of use over the course of its evolution.
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Swann, p. 242. In 1880, Lewis Latimer, a draftsman and an expert witness in patent litigation, began working for the United States Electric Lighting Company run by Edison's rival Hiram S. Maxim. While working for Maxim, Latimer invented a process for making carbon filaments for light bulbs and helped install broad- scale lighting systems for New York City, Philadelphia, Montreal, and London. Latimer holds the patent for the electric lamp issued in 1881, and a second patent for the “process of manufacturing carbons” (the filament used in incandescent light bulbs), issued in 1882.
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The spectral data for juglone confirms its bicyclic structure which contains a hydroxyl group as well as two carbonyl groups. The IR for juglone shows peaks at 3400 cm-1, 1662 cm-1, and 1641 cm-1 which are characteristic of the hydroxyl and carbonyl groups. The 13C NMR shows 10 peaks indicating the correct number of unique carbon atoms in the molecule as well as peaks at 160.6 ppm, 183.2 ppm, and 189.3 ppm for the carbon attached to the hydroxyl group and the two carbons part of the two carbonyl groups.
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There are four structural variations, contributing to the complexity of the membrane lipids in function and properties. The two phytanyl chains can form a 36-member ring to yield macrocyclic archaeol. Hydroxylated archaeol has phytanyl chains hydroxylated at the first tertiary carbon atom, while sesterterpanyl archaeol have the phytanyl side chains with C25 sesterterpanyl chains, substituting at C2 of glycerol or at both carbons. Unsaturated archaeol, with the same carbon skeleton as standard archaeol but one or multiple double bonds in the phytanyl side chains is also discovered.
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About a few thousand monomers typically comprise a chain of polystyrene, giving a molecular weight of 100,000–400,000 g/mol. center Each carbon of the backbone has tetrahedral geometry, and those carbons that have a phenyl group (benzene ring) attached are stereogenic. If the backbone were to be laid as a flat elongated zig-zag chain, each phenyl group would be tilted forward or backward compared to the plane of the chain. The relative stereochemical relationship of consecutive phenyl groups determines the tacticity, which affects various physical properties of the material.
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The Boord olefin synthesis is an organic reaction forming alkenes from ethers carrying a halogen atom 2 carbons removed from the oxygen atom (β-halo-ethers) using a metal such as magnesium or zinc. The reaction, discovered by Cecil E. Boord in 1930 The synthesis of beta-bromo-alkyl ethers and their use in further synthesis Lloyd C. Swallen and Cecil E. Boord J. Am. Chem. Soc.; 1930; 52(2) pp 651 - 660; is a classic named reaction with high yields and broad scope.Advanced Organic Chemistry, 4th Edition, Jerry March, 1992.
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Mersen, previously named Carbone Lorraine (until May 20, 2010), was created in 1891 by the Compagnie lorraine de charbons pour l’électricité in Pagny-sur-Moselle (Lorraine), where the Group still owns a plant. In 1937, it merged with Le Carbone, a company based in Gennevilliers, (Hauts-de-Seine) where the Group kept and operated the original plant.Carbone Lorraine's factory in GennevilliersLa Compagnie lorraine de charbons pour l’électricité was founded in Meurthe-et-Moselle in1891. It first manufactured motors, dynamos and lighting lamps before producing « carbons » for electric lighting.
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Absence of carbyne crystalline rendered the direct observation of a pure carbyne- assembled solid still a major challenge, because carbyne crystals with well- defined structures and sufficient sizes are not available to date. This is indeed the major obstacle to general acceptance of carbyne as a true carbon allotrope. The mysterious carbyne still attracted scientists with its possible extraordinary properties. In 1984, a group at Exxon reported the detection of clusters with even numbers of carbons, between 30 and 180, in carbon evaporation experiments, and attributed them to polyyne carbon. As cited by Kroto(2010).
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The amphiphilic nature of the moenomycins induce hemolytic activity, provide a long half-life in the blood stream, and creates a tendency to aggregate in aqueous solution. Comparison of moenomycins with an abridged isoprene chain of 10-carbons, show that the oligosaccharide can still tightly bind the enzyme active site, but in vivo the MIC significantly increases since the drug is unable to anchor itself to the cytoplasmic membrane and present its sugar moiety. Further studies are needed to determine the optimal length for favorable pharmacokinetic properties.Anikin, A., et al.
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EETS are epoxide eicosatrienoic acid metabolites of arachidonic acid (a straight chain Eicosatetraenoic acid, omega-6 fatty acid). Arachidonic acid has 4 cis double bonds (see Cis–trans isomerism which are abbreviated with the notation Z in the IUPAC Chemical nomenclature used here. These double bonds are located between carbons 5-6, 8-9, 11-12, and 14-15; arachidonic acid is therefore 5Z,8Z,11Z,14Z-eicosatetraenoic acid. Cytochrome P450 epoxygenases attack these double bonds to form their respective eicosatrienoic acid epoxide regioisomers (see Structural isomer, section on position isomerism (regioisomerism)) viz.
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Two sp3 (tetrahedral) carbons are created at this stage, which allows two different diastereomeric possibilities of the halohydrin intermediate. The most likely result is due to chemical kinetics: whichever product is easier and faster to form will be the major product of this reaction. The subsequent SN2 reaction step proceeds with stereochemical inversion, so the cis or trans form of the epoxide is controlled by the kinetics of an intermediate step. Alternately, the halohydrin can epimerize due to the basic nature of the reaction conditions prior to the SN2 reaction.
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In chemical nomenclature, nor- is a prefix to name a structural analog that can be derived from a parent compound by the removal of one carbon atom along with the accompanying hydrogen atoms. The nor-compound can be derived by removal of a , , or CH group, or of a C atom. The "nor-" prefix also includes the elimination of a methylene bridge in a cyclic parent compound, followed by ring contraction. (The prefix "homo-" which indicates the next higher member in a homologous series, is usually limited to noncyclic carbons).
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This core ring structure contains an epoxide, or tricyclic ether, at the 12,13 carbon positions, as well as a double bond at the 9, 10 carbon positions. These two functional groups are primarily responsible for trichothecene ability to inhibit protein synthesis and incur general cytotoxic effects. Notably, this core structure is amphipathic, containing both polar and non polar parts. All trichothecenes are related through this common structure, but each trichothecene also has a unique substitution pattern of oxygen containing functional groups at possible sites on carbons 3,4,7,8, and 15.
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Decenoic acid is any mono-carboxylic acid with an unbranched chain of ten carbons connected by eight single bonds and one double bond; that is, a chemical compound with formula ––––H, where k is between 0 and 7 inclusive. There are fifteen of these compounds, that can be identified by the position k+2 of the double bond and (for k ≤ 6) the configuration (cis or trans) of the single bonds adjacent to it. Decenoic acids are technically mono-unsaturated fatty acids (with code C10:1), although they are relatively rare in nature.
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Additionally, because 2-chlorobutane is antiperiplanar, it can undergo E2 elimination reactions with strong bases. In it, the chlorine leaving group is removed, and the double bond is restored to yield different constitutional isomers2. This is because 2-chlorobutane possesses two different sets of β-hydrogens at the first and third carbons respectively, resulting in 1-butene or 2-butene. It is important to note that as a secondary alkyl halide, both E2 and Sn2 reactions are equally likely when reacting with a substance that can act as both a base and a nucleophile.
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In nuclear magnetic resonance spectroscopy, the highly abundant 12C isotope does not produce any signal whereas the comparably rare 13C isotope is easily detected. As a result, carbon isotopomers of a compound can be studied by carbon-13 NMR to learn about the different carbon atoms in the structure. Each individual structure that contains a single 13C isotope provides data about the structure in its immediate vicinity. A large sample of a chemical contains a mixture of all such isotopomers, so a single spectrum of the sample contains data about all carbons in it.
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There was some evidence that sun tanning did help in the remission of the disease, but Perrysburg—40 miles south of Buffalo—had very little sunshine in the winter. Therefore, O'Brien, as a physicist on staff, developed a carbon arcs with cored carbons that very closely matched the solar spectrum. With this development the patients could have sun therapy year-round. Due to a general interest in biological effects of solar radiation, he published some of the early work on the ozone layer and erythema caused by the sun.
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The formation of chiral quaternary carbon centers has been a synthetic challenge. Chemists have developed asymmetric Diels–Alder reactions, Nicolaou, K. C.; Vassilikogiannakis, G.; Mägerlein, W.; Kranich, R Angew. Chem. Int. Ed. Volume 2001, Issue 40 , Pages 2482–2486 Heck reaction, Enyne cyclization, cycloaddition reactions, Quasdorf, K.W.; Overman, L. E. Nature Volume 2014, Volume 516, Pages 181 C–H activation, Allylic substitution, Pauson–Khand reaction, Ishizaki, M.; Niimi, Y.; Hoshino, O.; Hara, H.; Takahashi, T. Tetrahedron Volume 2001, Issue 61, Pages 4053–4065 etc. to construct asymmetric quaternary carbons.
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22R-Hydroxycholesterol, or (3β)-cholest-5-ene-3,22-diol is an endogenous, metabolic intermediate in the biosynthesis of the steroid hormones from cholesterol. Cholesterol ((3β)-cholest-5-en-3-ol) is hydroxylated by cholesterol side-chain cleavage enzyme (P450scc) to form 22R-hydroxycholesterol, which is subsequently hydroxylated again by P450scc to form 20α,22R-dihydroxycholesterol, and finally the bond between carbons 20 and 22 is cleaved by P450scc to form pregnenolone ((3β)-3-hydroxypregn-5-en-20-one), the precursor to the steroid hormones. It is an agonist of the liver X receptor.
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A study done in 2007 revealed that A. insinuator workers emitted far fewer hydrocarbons in total in comparison to A. echinatior. Hydrocarbons with 29-35 carbons are used as recognition cues in A. echinatior. A decrease in the normal 29-35 carbon hydrocarbon range, while an increase in heavier 43-45 carbon hydrocarbon was discovered as the means through which A. insinuator workers remained chemically insignificant. With fewer recognition hydrocarbons being produced, and heavier hydrocarbons masking any remaining identifying aspects, A. insinuator is able to successfully infiltrate an A. echinatior colony and remain undetected.
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Priori Determination Of Favored Conformers - NMR Study Of Conformation Equilibrium. Bulletin De La Societe Chimique De France, 3616 The compound is decomposed by butyllithium with cleavage of the ring, and this reaction has been considered as a way of obtaining lithium enolates of aldehydes. In a superacid solution (--), the oxygen atom is protonated, and the carbon chain is split at the 3-4 bond, which gets replaced by bonds from carbons 3 and 4 to the oxygen atom. The formula of the resulting species could be written as (–()2C-CH2–)2.
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Archibald Scott Couper in 1858 and Joseph Loschmidt in 1861 suggested possible structures that contained multiple double bonds or multiple rings, but the study of aromatic compounds was in its earliest years, and too little evidence was then available to help chemists decide on any particular structure. More evidence was available by 1865, especially regarding the relationships of aromatic isomers. Kekulé argued for his proposed structure by considering the number of isomers observed for derivatives of benzene. For every monoderivative of benzene (C6H5X, where X = Cl, OH, CH3, NH2, etc.) only one isomer was ever found, implying that all six carbons are equivalent, so that substitution on any carbon gives only a single possible product. For diderivatives such as the toluidines, C6H4(NH2)(CH3), three isomers were observed, for which Kekulé proposed structures with the two substituted carbon atoms separated by one, two and three carbon-carbon bonds, later named ortho, meta, and para isomers respectively. The counting of possible isomers for diderivatives was however criticized by Albert Ladenburg, a former student of Kekulé, who argued that Kekulé's 1865 structure implied two distinct "ortho" structures, depending on whether the substituted carbons are separated by a single or a double bond.
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These interactions, called transannular interactions, arise from a lack of space in the interior of the ring, which forces substituents into conflict with one another. In medium-sized cycloalkanes, which have between 8 and 11 carbons constituting the ring, transannular strain can be a major source of the overall strain, especially in some conformations, to which there is also contribution from large-angle strain and Pitzer strain.Smith and March, March's Advanced Organic Chemistry, John Wiley & Sons Inc., 2007, In larger rings, transannular strain drops off until the ring is sufficiently large that it can adopt conformations devoid of any negative interactions.
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Thus a fat or fatty acid molecule with double bonds (excluding at the very end of the chain) can have multiple cis-trans isomers with significantly different chemical and biological properties. Each double bond reduces the number of conformational degrees of freedom by one. Each triple bond forces the four nearest carbons to lie in a straight line, removing two degrees of freedom. It follows that depictions of "saturated" fatty acids with no double bonds (like stearic) having a "straight zig-zag" shape, and those with one cis bond (like oleic) being bent in an "elbow" shape are somewhat misleading.
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However 1% of the stilbene molecules will have a 13C atom on one of these double bond carbons (i.e. Ph-13CH=12CH-Ph). In this situation, the proton adjacent to 13C atom will couple to the 13C atom to give a wide doublet. Also, as this molecule is no longer symmetric the 13C _H_ = proton will now couple to the adjacent 12C _H_ = proton, causing a further doubleting. Thus this additional coupling (additional to the 13C coupling) is diagnostic of the type of double bond, and will allow one to determine if the stilbene molecule has a cis- or trans- configuration i.e.
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The cytosolic acetyl-CoA is carboxylated by acetyl CoA carboxylase into malonyl- CoA, the first committed step in the synthesis of fatty acids. Malonyl-CoA is then involved in a repeating series of reactions that lengthens the growing fatty acid chain by two carbons at a time. Almost all natural fatty acids, therefore, have even numbers of carbon atoms. When synthesis is complete the free fatty acids are nearly always combined with glycerol (three fatty acids to one glycerol molecule) to form triglycerides, the main storage form of fatty acids, and thus of energy in animals.
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Fatty acids that are required for good health but cannot be made in sufficient quantity from other substrates, and therefore must be obtained from food, are called essential fatty acids. There are two series of essential fatty acids: one has a double bond three carbon atoms away from the methyl end; the other has a double bond six carbon atoms away from the methyl end. Humans lack the ability to introduce double bonds in fatty acids beyond carbons 9 and 10, as counted from the carboxylic acid side. Two essential fatty acids are linoleic acid (LA) and alpha-linolenic acid (ALA).
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First total synthesis of physostigmine Julian & Pikl (1935) Physostigmine has two stereocenters—the two carbons where the five-membered rings join together—so any attempt at the total synthesis must pay attention to obtaining the correct stereoisomer. The 71 syntheses of physostigmine yield 33 racemic mixtures and 38 products of a single enantiomer. The first total synthesis of physostigmine was achieved by Julian and Pikl in 1935. The main goal of Julian's formal physostigmine synthesis was to prepare the key compound (L)-eseroline (compound 10 in the adjacent diagram), the conversion of which to physostigmine would be straightforward.
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Carbons from dietary fructose are found in both the FFA and glycerol moieties of plasma TG. Excess dietary fructose can be converted to pyruvate, enter the Krebs cycle and emerges as citrate directed toward free fatty acid synthesis in the cytosol of hepatocytes. The DHAP formed during fructolysis can also be converted to glycerol and then glycerol 3-phosphate for TG synthesis. Thus, fructose can provide trioses for both the glycerol 3-phosphate backbone, as well as the free fatty acids in TG synthesis. Indeed, fructose may provide the bulk of the carbohydrate directed toward de novo TG synthesis in humans.
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The use of diamond-like carbon for short is generally one of the nano films used to inhibit abrasion. A possible nano film that could be used to counteract temperature changes are the pure metals Ag (silver) and Au (gold). Silver and gold can withstand high temperatures and remain soft, which is desirable for coating properties. Using a lattice matrix (a template for the coating using the basket weave design), nano engineers are able to utilize properties of the diamond-like carbons and pure metals to make chameleon coatings more adaptable at even more varied environments.
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Very long-chain acyl-CoA synthetase is an enzyme that in humans is encoded by the SLC27A2 gene. The protein encoded by this gene is an isozyme of long-chain fatty-acid-coenzyme A ligase family. Although differing in substrate specificity, subcellular localization, and tissue distribution, all isozymes of this family convert free long-chain fatty acids into fatty acyl-CoA esters, and thereby play a key role in lipid biosynthesis and fatty acid degradation. This isozyme activates long-chain, branched-chain and very long chain fatty acids containing 22 or more carbons to their CoA derivatives.
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Tethered intramolecular [2+2] reactions entail the formation of cyclobutane and cyclobutanone via intramolecular 2+2 photocycloadditions. Tethering ensures formation of a multi-cyclic system. Figure 1 - tethered intramolecular [2+2] reactions The length of the tether affects the stereochemical outcome of the [2+2] reaction. Longer tethers tend to generate the "straight" product where the terminal carbon of the alkene is linked to the \alpha-carbon of the enone. When the tether consists only two carbons, the “bent” product is generated where the \beta-carbon of the enone is connected to the terminal carbon of the alkene (Figure 2).
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Reaction catalyzed by succinate dehydrogenase, note the double bond formed between the two central carbons when two hydrogens are removed In the above case, the dehydrogenase has transferred a hydride while releasing a proton, H+, but dehydrogenases can also transfer two hydrogens, using FAD as an electron acceptor. This would be depicted as AH2 \+ B ↔ A + BH2. A double bond is normally formed in between the two atoms that the hydrogens were taken from, as in the case of succinate dehydrogenase. The two hydrogens have been transferred to the carrier or the other product, with their electrons.
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Manganese triacetate has been used as a one-electron oxidant. It can oxidize alkenes via addition of acetic acid to form lactones. :300px This process is thought to proceed via the formation of a •CH2CO2H radical intermediate, which then reacts with the alkene, followed by additional oxidation steps and finally ring closure. When the alkene is not symmetric, the major product depends on the nature of the alkene, and is consistent with initial formation of the more stable radical (among the two carbons of the alkene) followed by ring closure onto the more stable conformation of the intermediate.
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Representative ketones, from the left: acetone, a common solvent; oxaloacetate, an intermediate in the metabolism of sugars; acetylacetone in its (mono) enol form (the enol highlighted in blue); cyclohexanone, precursor to nylon; muscone, an animal scent; and tetracycline, an antibiotic. The ketone carbon is often described as "sp2 hybridized", a description that includes both their electronic and molecular structure. Ketones are trigonal planar around the ketonic carbon, with C−C−O and C−C−C bond angles of approximately 120°. Ketones differ from aldehydes in that the carbonyl group (CO) is bonded to two carbons within a carbon skeleton.
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Thus, a bromonium ion that bridges a primary and tertiary carbon will often exhibit a skewed structure, with a weak bond to the tertiary center (with significant carbocation character) and stronger bond to the primary carbon. This is due to the increased stability of tertiary carbons to stabilize positive charge. In the more extreme case, if the tertiary center is doubly benzylic for instance, then the open form may be favored. Similarly, switching from bromine to chlorine also weakens bridging character, due to the higher electronegativity of chlorine and lower propensity to share electron density compared to bromine.
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The covalent bonds in this material form extended structures, but do not form a continuous network. With cross-linking, however, polymer networks can become continuous, and a series of materials spans the range from Cross-linked polyethylene, to rigid thermosetting resins, to hydrogen-rich amorphous solids, to vitreous carbon, diamond-like carbons, and ultimately to diamond itself. As this example shows, there can be no sharp boundary between molecular and network covalent solids. Intermediate kinds of bonding: A solid with extensive hydrogen bonding will be considered a molecular solid, yet strong hydrogen bonds can have a significant degree of covalent character.
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Other simple cations such as protonated acetylene (ethynium, ), protonated ethylene (ethenium, ), and protonated ethane (ethanium, ) have been shown to be best described as non- classical through infrared spectroscopy. The most frequently proposed molecular orbital depiction of the 2-norbornyl cation is shown in Figure 3. Two p-type orbitals, one on each of carbons 1 and 2, interact with a sp- hybridized orbital on carbon 6 to form the hypovalent bond. Extended Hückel Theory calculations for the 2-norbornyl cation suggest that the orbital on carbon 6 could instead be sp-hybridized, though this only affects the geometry of the geminal hydrogens.
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If a system is undergoing a rapid equilibrium at a rate faster than the timescale of a C NMR experiment, the relevant peak will be split dramatically (on the order of 10-100 ppm). If the system is instead static, the peak will be split very little. The C NMR spectrum of the 2-norbornyl cation at -150 °C shows that the peaks corresponding to carbons 1 and 2 are split by less than 10 ppm (parts per million) when this experiment is carried out, indicating that the system is not undergoing a rapid equilibrium as in the classical picture.
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At room temperature, thiophene is a colorless liquid with a mildly pleasant odor reminiscent of benzene, with which thiophene shares some similarities. The high reactivity of thiophene toward sulfonation is the basis for the separation of thiophene from benzene, which are difficult to separate by distillation due to their similar boiling points (4 °C difference at ambient pressure). Like benzene, thiophene forms an azeotrope with ethanol. The molecule is flat; the bond angle at the sulfur is around 93°, the C–C–S angle is around 109°, and the other two carbons have a bond angle around 114°.
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Pivaldehyde is an organic compound, more specifically an aldehyde. Shown in the image is a line-angle representation of this organic aldehyde, whose systematic name, 2,2-dimethylpropanal, is based on the longest carbon chain (three carbons), ending in "-al" to indicate the aldehyde functionality, and where another descriptive synonym is trimethylacetaldehyde. Pivaldehyde is an example of an aldehyde with a sterically bulky R group, the tertiary-butyl group (with 3 methyl groups, at lower left in the image), attached to the carbonyl, >C=O. By definition, the other "group", R', is a hydrogen (H) atom, shown here pointing directly upward.
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Aluminium, like its congener boron, is less electronegative than carbon (Al, 1.61; C, 2.55); thus, aluminium-bound carbons in organoalanes possess partial negative charge and are nucleophilic as a result. Generally, however, organoalanes are not nucleophilic enough to transfer an organic group on their own (the exception being when carbonyl and enone acceptors are used, due to the high oxophilicity of aluminiumCollins, P. W.; Dajani, E. Z.; Bruhn, M. S.; Brown, C. H.; Palmer, J. H.; Pappo, R. Tetrahedron Lett. 1975, 4217.). In most cases, nucleophilic activation of organoalanes is necessary for group transfer to take place.
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By using a series of disproportionation reactions of symmetrical and asymmetrical framework, Benson and Buss concluded that neighboring atoms within the disproportionation reaction under study are not affected by the change. ; Symmetrical : Cl-CH2CH2-Cl + H-CH2CH2-H -> 2 Cl- CH2CH2-H ; Asymmetrical : H-CH2O-H + CH3-CH2CH2-CH3 -> CH3-CH2O-H + H-CH2O-CH3 In the symmetrical reaction the cleavage between the CH2 in both reactants leads to one product formation. that the neighboring carbons are not changed as the rearrangement occurs. In the asymmetrical reaction the hydroxyl–methyl bond is cleaved and rearranged on the ethyl moiety of the methoxyethane.
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Chloroprene is produced in three steps from 1,3-butadiene: (i) chlorination, (ii) isomerization of part of the product stream, and (iii) dehydrochlorination of 3,4-dichlorobut-1-ene. Chlorine adds to 1,3-butadiene to afford a mixture of 3,4-dichlorobut-1-ene and 1,4-dichlorobut-2-ene. The 1,4-dichloro isomer is subsequently isomerized to 3,4 isomer, which in turn is treated with base to induce dehydrochlorination to 2-chlorobuta-1,3-diene. This dehydrohalogenation entails loss of a hydrogen atom in the 3 position and the chlorine atom in the 4 position thereby forming a double bond between carbons 3 and 4.
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Five-membered NHSis can be classified by the bonding in the two-carbon backbone of their rings. Saturated NHSis have two methylene units, the unsaturated have doubly- bonded methine carbons, and the benzo-fused NHSis share their carbon backbone with a fused aromatic ring. Though other N substituents such as aryl groups are also well known, in general, studies are conducted with tert-butyl groups bonded the nitrogen of the saturated and unsaturated NHSis, while the benzo- fused have neopentyl groups. X-ray crystallography and electron diffraction show significant differences between the saturated and unsaturated structures.
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One government study in the late 1980s determined that nearly 5 million tons of contaminants were emitted annually in the atmosphere, a tenfold increase over the previous decade. Carbons and hydrocarbons from the region's more than 3 million vehicles account for approximately 80% of these contaminants, with another 15%, primarily of sulfur and nitrogen, coming from industrial plants. The resulting dangerous mix is responsible for a wide range of respiratory illnesses. One study of twelve urban areas worldwide in the mid-1980s concluded that the residents of Mexico City had the highest levels of lead and cadmium in their blood.
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Members of the enediyne family all share a unique enediyne core that is the cause of their potent cytotoxicity. The enediyne cores are derived from linear, probably polyketide, precursors that consist of seven or eight head-to-tail coupled acetate units. Enediyne assembly involves a highly conserved, iterative type I polyketide synthase (PKS) pathway Sequencing of enediyne gene clusters has confirmed the polyketide origin of the enediyne core, and elucidated the biosynthetic pathways and mechanisms of enediynes. Differences in the biosynthetic pathways of enediynes are due to the different origins of the -yne carbons as well as differences in isotope incorporation patterns.
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Ribose is a constituent of RNA, and the related molecule, deoxyribose, is a constituent of DNA. Phosphorylated pentoses are important products of the pentose phosphate pathway, most importantly ribose 5-phosphate (R5P), which is used in the synthesis of nucleotides and nucleic acids, and erythrose 4-phosphate (E4P), which is used in the synthesis of aromatic amino acids. Like some other monosaccharides, pentoses exist in two forms, open-chain (linear) or closed- chain (cyclic), that easily convert into each other in water solutions. The linear form of a pentose, which usually exists only in solutions, has an open- chain backbone of five carbons.
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Overview of the Glyoxylate Cycle The glyoxylate cycle, a variation of the tricarboxylic acid cycle, is an anabolic pathway occurring in plants, bacteria, protists, and fungi. The glyoxylate cycle centers on the conversion of acetyl-CoA to succinate for the synthesis of carbohydrates. In microorganisms, the glyoxylate cycle allows cells to utilize two carbons (C2 compounds), such as acetate, to satisfy cellular carbon requirements when simple sugars such as glucose or fructose are not available. The cycle is generally assumed to be absent in animals, with the exception of nematodes at the early stages of embryogenesis.
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To cope with the wide variety of phenolic compounds found in nature, bacterial pathways for degradation of aromatic compounds generally begin by channeling these diverse substrates towards a few common intermediates, which are then further degraded. Pathways for catabolizing aromatic compounds generally begin by adding two hydroxyl groups to the benzene ring, most often on adjacent carbons. This product then undergoes ring cleavage to produce a linear molecule which is ultimately degraded to intermediates of central metabolism, such as succinate, pyruvate, and carbon dioxide. In the case of 4-hydroxyphenylacetate, which only needs one hydroxyl group to be added, a monooxygenase is required.
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1,3-diaxial strain is another form of strain similar to syn-pentane. In this case, the strain occurs due to steric interactions between a substituent of a cyclohexane ring ('α') and gauche interactions between the alpha substituent and both methylene carbons two bonds away from the substituent in question (hence, 1,3-diaxial interactions). When the substituent is axial, it is brought near to an axial gamma hydrogen. The amount of strain is largely dependent on the size of the substituent and can be relieved by forming into the major chair conformation placing the substituent in an equatorial position.
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Adenosine 3',5'-bisphosphate is a form of an adenosine nucleotide with two phosphate groups attached to different carbons in the ribose ring. This is distinct from adenosine diphosphate, where the two phosphate groups are attached in a chain to the 5' carbon atom in the ring. Adenosine 3',5'-bisphosphate is produced as a product of sulfotransferase enzymes from the donation of a sulfate group from the coenzyme 3'-phosphoadenosine-5'-phosphosulfate. This product is then hydrolysed by 3'(2'),5'-bisphosphate nucleotidase to give adenosine monophosphate, which can then be recycled into adenosine triphosphate.
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The tricalcium phosphate in bone char can be used to remove fluoride and metal ions from water, making it useful for the treatment of drinking supplies. Bone charcoal is the oldest known water defluoridation agent and was widely used in the United States from the 1940s through to the 1960s. As it can be generated cheaply and locally it is still used in certain developing countries, such as Tanzania. Bone chars usually have lower surface areas than activated carbons, but present high adsorptive capacities for certain metals, particularly those from group 12 (copper, zinc, and cadmium).
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Fatty acid desaturase 2 is a member of the fatty acid desaturase (FADS) gene family. Desaturase enzymes cause desaturation of fatty acids through the introduction of double bonds between defined carbons of the fatty acyl chain. FADS family members are considered fusion products composed of an N-terminal cytochrome b5-like domain and a C-terminal multiple membrane- spanning desaturase portion, both of which are characterized by conserved histidine motifs. This gene is clustered with family members FADS1 and FADS2 at 11q12-q13.1; this cluster is thought to have arisen evolutionarily from gene duplication based on its similar exon/intron organization.
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By example, α-linolenic acid (ALA; illustration) is an 18-carbon chain having three double bonds, the first being located at the third carbon from the methyl end of the fatty acid chain. Hence, it is an omega–3 fatty acid. Counting from the other end of the chain, that is the carboxyl end, the three double bonds are located at carbons 9, 12, and 15. These three locants are typically indicated as Δ9c,12c,15c, or cisΔ9,cisΔ12,cisΔ15, or cis-cis-cis-Δ9,12,15, where c or cis means that the double bonds have a cis configuration.
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Wilcox is the first author to publish a textbook on carbon capture. Her book, Carbon Capture published in March 2012, discusses the fundamental chemical concepts ranging from thermodynamics, combustion, kinetics, mass transfer, material properties, and the relationship between the chemistry and process of carbon capture technologies. , Wilcox also authored or co-authored 182 papers and publications. Her top three cited papers include the "Methane leaks from North American natural gas systems", "Molecular simulation of methane adsorption in micro-and mesoporous carbons with applications to coal and gas shale systems", and "Carbon capture and storage (CCS): the way forward".
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The various decadienoic acid isomers can be distinguished by the positions of their double bonds along the chain. A double bond is said to be at position k if it connects carbons k and k+1 of the chain, counting from 1 at the carboxyl end. The positions are x+2 and x+y+4 for the first type (21 possibilities), and r+2 and r+3 for the second type (7 possibilities). The systematic name of the acid is formed by prefixing the positions of the double bonds to "decadienoic" or inserting them before the "dienoic" suffix.
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I have not changed my opinion of the book > since… I do recall a fine description of men carrying a dying man down a > mountain… Yet every time I got going in the narrative I would find myself > stopped cold by a set of made-up, predictable characters taken not from > life, but from the same novels all of us had read, and informed by a naïveté > which was at its worst when Mailer went into his Time-Machine and wrote > those passages which resemble nothing so much as smudged carbons of a Dos > Passos work.
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The various classifications above can be combined, resulting in names such as "aldohexose" and "ketotriose". A more general nomenclature for open-chain monosaccharides combines a Greek prefix to indicate the number of carbons (tri-, tetr-, pent-, hex-, etc.) with the suffixes "-ose" for aldoses and "-ulose" for ketoses. In the latter case, if the carbonyl is not at position 2, its position is then indicated by a numeric infix. So, for example, H(C=O)(CHOH)4H is pentose, H(CHOH)(C=O)(CHOH)3H is pentulose, and H(CHOH)2(C=O)(CHOH)2H is pent-3-ulose.
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In these cyclic forms, the ring usually has five or six atoms. These forms are called furanoses and pyranoses, respectively — by analogy with furan and pyran, the simplest compounds with the same carbon-oxygen ring (although they lack the double bonds of these two molecules). For example, the aldohexose glucose may form a hemiacetal linkage between the hydroxyl on carbon 1 and the oxygen on carbon 4, yielding a molecule with a 5-membered ring, called glucofuranose. The same reaction can take place between carbons 1 and 5 to form a molecule with a 6-membered ring, called glucopyranose.
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For example, in the image below, the skeletal formula of hexane is shown. The carbon atom labeled C1 appears to have only one bond, so there must also be three hydrogens bonded to it, in order to make its total number of bonds four. The carbon atom labelled C3 has two bonds to other carbons and is therefore bonded to two hydrogen atoms as well. A ball-and-stick model of the actual molecular structure of hexane, as determined by X-ray crystallography, is shown for comparison, in which carbon atoms are depicted as black balls and hydrogen atoms as white ones.
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General mechanism in the Stickland fermentation Stickland fermentation exempflified with D-alanine and glycine Stickland fermentation or The Stickland Reaction is the name for a chemical reaction that involves the coupled oxidation and reduction of amino acids to organic acids. The electron donor amino acid is oxidised to a volatile carboxylic acid one carbon atom shorter than the original amino acid. For example, alanine with a three carbon chain is converted to acetate with two carbons. The electron acceptor amino acid is reduced to a volatile carboxylic acid the same length as the original amino acid.
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HNCA is a 3D triple-resonance NMR experiment commonly used in the field of protein NMR. The name derives from the experiment's magnetization transfer pathway: The magnetization of the amide proton of an amino acid residue is transferred to the amide nitrogen, and then to the alpha carbons of both the starting residue and the previous residue in the protein's amino acid sequence. In contrast, the complementary HNCOCA experiment transfers magnetization only to the alpha carbon of the previous residue. The HNCA experiment is used, often in tandem with HNCOCA, to assign alpha carbon resonance signals to specific residues in the protein.
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With a melting point of 68.5–72.5 °C, candelilla wax consists of mainly hydrocarbons (about 50%, chains with 29–33 carbons), esters of higher molecular weight (20–29%), free acids (7–9%), and resins (12–14%, mainly triterpenoid esters). The high hydrocarbon content distinguishes this wax from carnauba wax.Uwe Wolfmeier,Hans Schmidt, Franz-Leo Heinrichs, Georg Michalczyk, Wolfgang Payer,Wolfram Dietsche, Klaus Boehlke, Gerd Hohner, Josef Wildgruber "Waxes" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. It is insoluble in water, but soluble in many organic solvents such as acetone, chloroform, benzene, and turpentine.
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These peptide sequences are highly studied as sequence control leads to reliable folding prediction. Additionally, with multiple methylene carbons between the carboxyl and amino termini of the flanking peptide bonds, Varying R group side chains can be designed. One example of the novelty of β-peptides can be seen in the findings of Reiser and coworkers. Using a heteroligopeptide consisting of α-amino acids and cis-β-aminocyclopropanecarboxulic acids (cis- β-ACCs) they found the formation of helical sequences in oligomers as short as seven residues and defined conformation in five residues; a quality unique to peptides containing cyclic β-amino acids.
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EDPs are epoxide eicosapentaenoic acid metabolites of DHA. DHA has 6 cis (see Cis–trans isomerism) Double bonds each one of which is located between carbons 4-5, 7-8, 10-11, 13-14, 16-17, or 19-20. Cytochrome P450 epoxygenases attack any one of these double bounds to form a respective docosapentaenoic acid (DPA) epoxide regioisomer (see Structural isomer, section on position isomerism (regioisomerism)). A given epoxygenase may therefore convert DHA to 4,5-EDP (i.e. 4,5-epoxy-7Z,10Z,13Z,16Z,19Z-DPA), 7,8-EDP (i.e. 7,8-epoxy-4Z,10Z,13Z,16Z,19Z-DPA), 10,11-EDP (i.e.
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They are also commonly termed n-6 DPA and n-3 DPA, respectively; these designations describes the position of the double bond being 6 or 3 carbons closest to the (omega) carbon at the methyl end of the molecule and is based on the biologically important difference that n-6 and n-3 PUFA are separate PUFA classes, i.e. the omega-6 fatty acids and omega-3 fatty acids, respectively. Mammals, including humans, can not interconvert these two classes and therefore must obtain dietary essential PUFA fatty acids from both classes in order to maintain normal health (see essential fatty acids).
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All monosaccharides are reducing sugars because they either have an aldehyde group (if they are aldoses) or can tautomerize in solution to form an aldehyde group (if they are ketoses). This includes common monosaccharides like galactose, glucose, glyceraldehyde, fructose, ribose, and xylose. Many disaccharides, like cellobiose, lactose, and maltose, also have a reducing form, as one of the two units may have an open-chain form with an aldehyde group. However, sucrose and trehalose, in which the anomeric carbons of the two units are linked together, are nonreducing disaccharides since neither of the rings is capable of opening.
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Vitamin B12 Vitamin B12, C63H88CoN14O14P, is the most complex of all known vitamins. Its chemical structure had been determined by x-ray crystal structure analysis in 1956 by the research group of Dorothy Hodgkin (Oxford University) in collaboration with Kenneth N. Trueblood at UCLA and John G. White at Princeton University. Core of the molecule is the corrin structure, a nitrogenous tetradentate ligand system. This is biogenetically related to porphyrins and chlorophylls, yet differs from them in important respects: the carbon skeleton lacks one of the four meso carbons between the five-membered rings, two rings (A and D, fig.
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Heat coils, also known as protectors, bugs or carbons serve as a surge protector between the telephone exchange and outside plant. They are commonly the last point of appearance for a telephone circuit before it leaves the office, for example on the outside plant side of the main distribution frame. On some competitive local exchange carrier circuits there are two heat coils, the extra one being at the point of interface between their circuit and where the incumbent local exchange carrier or Regional Bell Operating Company receives it. Their primary purpose is to protect central office equipment from surges of high voltage.
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This experiment provides correlations between a carbon and its attached protons. The constant time (CT) version of 1H—13C HSQC is normally used as it circumvents the issue of splitting of signal due to homonuclear 13C—13C J couplings which reduces spectral resolution. The "constant time" refers to the entire evolution period between the two INEPT steps which is kept constant in this experiment. If this evolution period is set to be the inverse of the J-coupling constant, then the sign of the magnetization of those carbons with an odd number of aliphatic carbon attached will be opposite to those with an even number.
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Moreover, due to the specificity of most microbes along with complex aromatic structures, in order to achieve a complete dehalogenation, a mixture of more than one species of bacteria and/or fungi (often known as a consortium) is utilized. The reaction in figure 2 shows the reductive debromination of 2,4,6-tribromophenol (2,4,6-TBP) by Ochrabactrum. Based on the relative degradation of the molecule along with analytical results, it has been postulated that degradation of 2,4,6-TBP proceeds through debromination of ortho-bromine in the first step by a dehalogenase to yield 2,4-dibromophenol (2,4-DBP). Since there are two ortho bromines, debromination of either ortho carbons would yield the same product .
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Carbon–carbon bond-forming reactions are organic reactions in which a new carbon–carbon bond is formed. They are important in the production of many man-made chemicals such as pharmaceuticals and plastics. Some examples of reactions which form carbon–carbon bonds are aldol reactions, Diels–Alder reaction, the addition of a Grignard reagent to a carbonyl group, a Heck reaction, a Michael reaction and a Wittig reaction. The directed synthesis of desired three-dimensional structures for tertiary carbons was largely solved during the late 20th century, but the same ability to direct quaternary carbon synthesis did not start to emerge until the first decade of the 21st century.
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There are at least two isomers of the linear form of pentanone, a ketone that contains a chain of exactly five carbon atoms. There is an oxygen atom bonded to one of the middle three carbons (if it were bonded to an end carbon, the molecule would be an aldehyde, not a ketone), but it is not clear where it is located. In this example, the carbon atoms are numbered from one to five, which starts at one end and proceeds sequentially along the chain. Now the position of the oxygen atom can be defined as on carbon atom number two, three or four.
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Xylene exists in three isomeric forms. The isomers can be distinguished by the designations ortho- (o-), meta- (m-) and para- (p-), which specify to which carbon atoms (of the benzene ring) the two methyl groups are attached. By counting the carbon atoms around the ring starting from one of the ring carbons bonded to a methyl group, and counting towards the second methyl group, the o-isomer has the IUPAC name of 1,2-dimethylbenzene, the m-isomer is 1,3-dimethylbenzene and the p-isomer is 1,4-dimethylbenzene. Of the three isomers, the p-isomer is the most industrially sought after since it can be oxidized to terephthalic acid.
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The aldehyde group makes glucose a reducing sugar giving a positive reaction with the Fehling test. Each of the four carbons C-2 through C-5 is a stereocenter, meaning that its four bonds connect to four different substituents. (Carbon C-2, for example, connects to −(C=O)H, −OH, −H, and −(CHOH)4H.) In -glucose, these four parts must be in a specific three-dimensional arrangement. Namely, when the molecule is drawn in the Fischer projection, the hydroxyls on C-2, C-4, and C-5 must be on the right side, while that on C-3 must be on the left side.
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Monosaccharides with three carbon atoms are called trioses, those with four are called tetroses, five are called pentoses, six are hexoses, and so on. These two systems of classification are often combined. For example, glucose is an aldohexose (a six-carbon aldehyde), ribose is an aldopentose (a five-carbon aldehyde), and fructose is a ketohexose (a six-carbon ketone). Each carbon atom bearing a hydroxyl group (-OH), with the exception of the first and last carbons, are asymmetric, making them stereo centers with two possible configurations each (R or S). Because of this asymmetry, a number of isomers may exist for any given monosaccharide formula.
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Prenol lipid (2E-geraniol) Prenol lipids are synthesized from the five-carbon-unit precursors isopentenyl diphosphate and dimethylallyl diphosphate that are produced mainly via the mevalonic acid (MVA) pathway. The simple isoprenoids (linear alcohols, diphosphates, etc.) are formed by the successive addition of C5 units, and are classified according to number of these terpene units. Structures containing greater than 40 carbons are known as polyterpenes. Carotenoids are important simple isoprenoids that function as antioxidants and as precursors of vitamin A. Another biologically important class of molecules is exemplified by the quinones and hydroquinones, which contain an isoprenoid tail attached to a quinonoid core of non-isoprenoid origin.
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She received the Chancellor's Award for Excellence in Scholarship and Creative Activities from State University of New York in 2003 and was named Outstanding Inventor by State University of New York in 2002. In 1993, she was honored as "Teacher of the Year" by Tau Beta Pi (New York Nu). Chung was the first American woman and the first person of Chinese descent to receive the Charles E. Pettinos Award, in 2004; the award was in recognition of her work on functional carbons for thermal, electromagnetic and sensor applications. In 2005, she received the Hsun Lee Lecture Award from Institute of Metal Research, Chinese Academy of Sciences.
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The kin selection that is necessary for eusociality to evolve would require a signal that allows for related members of a species to recognize each other. A study has indicated that in F. truncorum this signal may be the hydrocarbon profile located on the cuticle of each ant. Further examination of these hydrocarbon chains has shown that many contain chains longer than 34 carbons, and while there is enough similarity between cuticles to recognize members of the same colony, they are still diverse enough to be distinct between colonies. Ants which are genetically similar have similar hydrocarbon profiles, which could allow kin to recognize one another through this similarity.
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In nature, the iron- molybdenum cofactor (FeMoco) responsible for microbial nitrogen fixation likewise has an octahedral carbon center (formally a carbide, C(-IV)) bonded to six iron atoms. In 2016, it was confirmed that, in line with earlier theoretical predictions, the hexamethylbenzene dication contains a carbon atom with six bonds. More specifically, the dication could be described structurally by the formulation [MeC(η5-C5Me5)]2+, making it an "organic metallocene" in which a MeC3+ fragment is bonded to a η5-C5Me5− fragment through all five of the carbons of the ring. This anthracene derivative contains a carbon atom with 5 formal electron pairs around it.
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Enoyl-CoA hydratase (ECH) or crotonase is an enzyme that hydrates the double bond between the second and third carbons on 2-trans/cis-enoyl-CoA: 460x460px File:Enoyl-CoA hydratase reaction cis.svg ECH is essential to metabolizing fatty acids in beta oxidation to produce both acetyl CoA and energy in the form of ATP. ECH of rats is a hexameric protein (this trait is not universal, but human enzyme is also hexameric), which leads to the efficiency of this enzyme as it has 6 active sites. This enzyme has been discovered to be highly efficient, and allows people to metabolize fatty acids into energy very quickly.
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Though characterization of 2-norbornyl cation crystals may have significantly precluded further debates about its electronic structure, it does not crystallize under any standard conditions. Recently, the crystal structure has been obtained and reported through a creative means: addition of aluminum tribromide to 2-norbornyl bromide in dibromomethane at low temperatures afforded crystals of [][]·. By examining the resulting crystal structure, researchers were able to confirm that the crystalline geometry best supports the case for delocalized bonding in the stable 2-norbornyl cation. Bond lengths between the "bridging" carbon 6 and each of carbons 1 and 2 were found to be slightly longer than typical alkane bonds.
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According to the nonclassical picture, one would expect a bond order between 0 and 1 for these bonds, signifying that this explains the crystal structure well. The bond length between carbons 1 and 2 was reported as being between typical single and double carbon-carbon bond lengths, which agrees with nonclassical predictions of a bond order slightly above 1. According to the non-classical picture, one would expect a bond order between 0 and 1 for the first two bonds. Investigators who crystallized the 2-norbornyl cation commented that the cation proved impossible to crystallize unless provided a chemical environment that locked it into one definite orientation.
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Synthesis of Okazaki fragments The work of Kiwako Sakabe, Reiji Okazaki and Tsuneko Okazaki provided experimental evidence supporting the hypothesis that DNA replication is a discontinuous process. Previously, it was commonly accepted that replication was continuous in both the 3' to 5' and 5' to 3' directions. 3' and 5' are specifically numbered carbons on the deoxyribose ring in nucleic acids, and refer to the orientation or directionality of a strand. In 1967, the Tsuneko Okazaki and Toru Ogawa suggested that there is no found mechanism that showed continuous replication in the 3' to 5' direction, only 5' to 3' using DNA polymerase, a replication enzyme.
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In these reactions, a positive electrophile attacks one of the unsaturated carbons that then forms a vinyl cation, which subsequently undergoes further reaction steps to form the final product. In the acid-catalyzed hydration of arylacetylene derivatives, a proton initially attacks the triple bond to form a vinyl cation at the aryl substituted carbon. The intermediate experiences little resonance stabilization because of the orthogonality of the conjugated aryl orbital with the empty p-orbital of the vinyl cation. The reaction is first order with respect to both the acetylene and the proton and with the protonation of the acetylene as the rate-determining step.
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The full biosynthesis of Absinthin in Artemisia absinthium has not been elucidated, but a great portion of it can be inferred from the natural product precursors required to access Absinthin. While terpenoids like Absinthin can be said to consist of isoprene "units," isoprene by itself is unstable and does not react directly. Rather, the isoprene units are transferred and reacted as diphosphates. As the nomenclature for terpenes suggests, the first Absinthin precursor farnesyl diphosphate [A] contains 15 carbons, or 3 isoprene units. Diphosphate departure (1) generates a carbo- cation within the synthase, which can then be attacked by a carbon-carbon double bond at the opposing end of the molecule (2).
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Each carbon atom in a diamond is covalently bonded to four other carbons in a tetrahedron. These tetrahedrons together form a 3-dimensional network of six-membered carbon rings (similar to cyclohexane), in the chair conformation, allowing for zero bond angle strain. This stable network of covalent bonds and hexagonal rings is the reason that diamond is so strong. Although graphite is the most stable allotrope of carbon under standard laboratory conditions (273 or 298 K, 1 atm), a recent computational study indicated that under idealized conditions (T = 0, p = 0), diamond is the most stable allotrope by 1.1 kJ/mol compared to graphite.
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Lolines increase resistance of endophyte-infected grasses to insect herbivores, and may also protect the infected plants from environmental stresses such as drought and spatial competition. They are alkaloids, organic compounds containing basic nitrogen atoms. The basic chemical structure of the lolines comprises a saturated pyrrolizidine ring, a primary amine at the C-1 carbon, and an internal ether bridge—a hallmark feature of the lolines, which is uncommon in organic compounds—joining two distant ring (C-2 and C-7) carbons (see Fig. 1). Different substituents at the C-1 amine, such as methyl, formyl, and acetyl groups, yield loline species that have variable bioactivity against insects.
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Four of these carbons have one hydroxyl functional group (–OH) each, connected by a single bond, and one has an oxygen atom connected by a double bond (=O), forming a carbonyl group (C=O). The remaining bonds of the carbon atoms are satisfied by six hydrogen atoms. Thus the structure of the linear form is H–(CHOH)x–C(=O)–(CHOH)4-x–H, where x is 0, 1, or 2. The term "pentose" sometimes is assumed to include deoxypentoses, such as deoxyribose: compounds with general formula that can be described as derived from pentoses by replacement of one or more hydroxyl groups with hydrogen atoms.
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2,2'-Dipyrromethene, often called just dipyrromethene or dipyrrin, is a chemical compound with formula whose skeleton can be described as two pyrrole rings connected by a methyne bridge =CH– through their nitrogen-adjacent (position-2) carbons; the remaining bonds being satisfied by hydrogen atoms. It is an unstable compound that is readily attacked by nucleophylic compounds above −40 °C. 2,2'-Dipyrromethene and its more stable and easily prepared derivatives—formally obtained by replacing one or more hydrogen atoms by other functional groups—are important precursors for the family of BODIPY fluorescent dies. The derivatives include salts of the dipyrrinato anion and of the cation .
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Surfactin's structure consists of a peptide loop of seven amino acids (L-aspartic acid, L-leucine, glutamic acid, L-leucine, L-valine and two D-leucines), and a hydrophobic fatty acid chain thirteen to fifteen carbons long which allows it to penetrate cellular membranes. Glutamic acid and aspartic acid residues at positions 1 and 5 respectively, constituting a minor polar domain. On the opposite side, valine residue at position 4 extends down facing the fatty acid chain, making up a major hydrophobic domain. Below critical micellar concentrations (CMCs) the fatty acid tail can extend freely into solution, and then participate in hydrophobic interactions within micelles.
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Vicinal difunctionalization reactions, most generally, lead to new bonds at two adjacent carbon atoms. Often this takes place in a stereocontrolled fashion, particularly if both bonds are formed simultaneously, as in the Diels-Alder reaction. Activated double bonds represent a useful handle for vicinal difunctionalization because they can act as both nucleophiles and electrophiles—one carbon is necessarily electron poor, and the other electron rich. In the presence of a nucleophile and an electrophile, then, the two carbons of a double bond can act as a "relay," mediating electron flow from the nucleophile to the electrophile with the formation of two, rather than the usual one, chemical bonds.
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In common usage, the prefix "PA" (polyamide) or the name "Nylon" are used interchangeably and are equivalent in meaning. The nomenclature used for nylon polymers was devised during the synthesis of the first simple aliphatic nylons and uses numbers to describe the number of carbons in each monomer unit, including the carbon(s) of the carboxylic acid(s). Subsequent use of cyclic and aromatic monomers required the use of letters or sets of letters. One number after "PA" or "Nylon" indicates a homopolymer which is monadic or based on one amino acid (minus H2O) as monomer: :PA 6 or Nylon 6: [NH−(CH2)5−CO]n made from ε-Caprolactam.
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The bulk, written between 1951 and 1953, presents Algren's philosophy as a writer, especially in the context of McCarthyism. The book was demanded by and given in June 1953 to his then-publisher Doubleday, but possibly due to the pressure of the FBI's then-ongoing investigation of Algren, Doubleday rejected it in September. Algren then sent it to his agent, but the manuscript was either lost in the mail or intercepted by the FBI, and the text salvaged from a carbon copy. In 1956, Algren gave those carbons to Van Allen Bradley, the Chicago Daily News editor who had commissioned the essay that inspired the book.
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The Centre conducts research in agroforestry, in partnership with national agricultural research systems with a view to developing more sustainable and productive land use. The focus of its research is countries/regions in the developing world, particular in the tropics of Central and South America, Southeast Asia, South Asia, West Africa, Eastern Africa and parts of central Africa. In 2002, the Centre acquired the World Agroforestry Centre brand name, although International Centre for Research in Agroforestry remains its legal name and it continues to use the acronym ICRAF. In 2017, ICRAF released a study at the UN Climate Change Conference that centers on Agroforestry and the emission of carbons from deforestation.
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HNCOCA is a 3D triple-resonance NMR experiment commonly used in the field of protein NMR. The name derives from the experiment's magnetization transfer pathway: The magnetization of the amide proton of an amino acid residue is transferred to the amide nitrogen, and then to the alpha carbon of the previous residue in the protein's amino acid sequence. In contrast, the complementary HNCA experiment transfers magnetization to the alpha carbons of both the starting residue and the previous residue in the sequence. The HNCOCA experiment is used, often in tandem with HNCA, to assign alpha carbon resonance signals to specific residues in the protein.
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The first of its kind was in Madras, called Edison's Grand Cinemamegaphone. This was due to the fact that electric carbons were used for motion picture projectors. Bombay Talkies opened in 1934 and Prabhat Studios in Pune began production of Marathi films meant. R. S. D. Choudhury produced Wrath (1930), which was banned by the British Raj for its depiction of Indian actors as leaders during the Indian independence movement. Sant Tukaram, a 1936 film based on the life of Tukaram (1608–50), a Varkari Sant and spiritual poet became the first Indian film to be screened at an international film festival, at the 1937 edition of the Venice Film Festival.
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Transketolase encoded by the TKT gene is an enzyme of both the pentose phosphate pathway in all organisms and the Calvin cycle of photosynthesis. It catalyzes two important reactions, which operate in opposite directions in these two pathways. In the first reaction of the non-oxidative pentose phosphate pathway, the cofactor thiamine diphosphate accepts a 2-carbon fragment from a 5-carbon ketose (D-xylulose-5-P), then transfers this fragment to a 5-carbon aldose (D-ribose-5-P) to form a 7-carbon ketose (sedoheptulose-7-P). The abstraction of two carbons from D-xylulose-5-P yields the 3-carbon aldose glyceraldehyde-3-P.
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Typically, water-treatment carbons have iodine numbers ranging from 600 to 1100. Frequently, this parameter is used to determine the degree of exhaustion of a carbon in use. However, this practice should be viewed with caution, as chemical interactions with the adsorbate may affect the iodine uptake, giving false results. Thus, the use of iodine number as a measure of the degree of exhaustion of a carbon bed can only be recommended if it has been shown to be free of chemical interactions with adsorbates and if an experimental correlation between iodine number and the degree of exhaustion has been determined for the particular application.
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The following is the reaction mechanism of a nucleophilic aromatic substitution of 2,4-dinitrochlorobenzene in a basic solution in water. Nucleophilic aromatic substitution In this sequence the carbons are numbered clockwise from 1–6 starting with the 1 carbon at 12 o'clock, which is bonded to the chloride. Since the nitro group is an activator toward nucleophilic substitution, and a meta director, it allows the benzene carbon to which it is bonded to have a negative charge. In the Meisenheimer complex, the nonbonded electrons of the carbanion become bonded to the aromatic pi system which allows the ipso carbon to temporarily bond with the hydroxyl group (-OH).
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Morphinan has a phenanthrene core structure with the A ring remaining aromatic and the B and C rings being saturated, and an additional nitrogen-containing, six-membered, saturated ring, the D ring, being attached to carbons 9 and 13 of the core, and with the nitrogen being at position 17 of the composite. Of the major naturally occurring opiates of the morphinan type—morphine, codeine and thebaine—thebaine has no therapeutic properties (it causes seizures in mammals), but it provides a low-cost feedstock for the industrial production of at least four semi-synthetic opiate agonists, including hydrocodone, hydromorphone, oxycodone and oxymorphone, and, perhaps more significantly, the opioid antagonist naloxone.
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The substitution of certain bulky groups on nitrogen 17 converts an opioid agonist into an opioid antagonist, the most important of which is naloxone, a non-selective opioid antagonist with no opioid agonist properties whatsoever ("silent" antagonist). Additionally, substitution of certain very bulky groups on carbon 6 converts naloxone into a peripherally-selective opioid antagonist with no centrally- selective antagonist properties (naloxegol). The addition of a two-carbon bridge between carbons 6 and 14 (e.g., 6,14-ethano, or 6,14-etheno), and which significantly distorts the C ring, may increase potency 1,000 to 10,000 times, or greater, compared to morphine, as in etorphine, and others.
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Angle strain in cycloalkynes arises from the deformation of the R–C≡C bond angle which must occur in order to accommodate the molecular geometry of rings containing less than ten carbons. The strain energies associated with cyclononyne (C9H14) and cyclooctyne (C8H12) are approximately 2.9 kcal/mol and 10 kcal/mol, respectively. This upwards trend in energy for the isolable constituents of this class is indicative of a rapid escalation of angle strain with an inverse correlation to ring size. Analysis by photoelectron spectroscopy has indicated that the alkyne bond in small cyclic systems is composed of two non-degenerate π bonds – a highly reactive strained bond perpendicular to a lower-energy π bond.
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Tritium (Hydrogen-3) is a very low beta energy emitter that can be used to label proteins, nucleic acids, drugs and almost any organic biomolecule. The maximum theoretical specific activity of tritium is 28.8 Ci/mmol (1.066 PBq/mol). However, there is often more than one tritium atom per molecule: for example, tritiated UTP is sold by most suppliers with carbons 5 and 6 each bonded to a tritium atom. For tritium detection, liquid scintillation counters have been classically employed, in which the energy of a tritium decay is transferred to a scintillant molecule in solution which in turn gives off photons whose intensity and spectrum can be measured by a photomultiplier array.
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The most commonly used electrode material for supercapacitors is carbon in various manifestations such as activated carbon (AC), carbon fibre-cloth (AFC), carbide-derived carbon (CDC), carbon aerogel, graphite (graphene), graphane and carbon nanotubes (CNTs). Carbon-based electrodes exhibit predominantly static double- layer capacitance, even though a small amount of pseudocapacitance may also be present depending on the pore size distribution. Pore sizes in carbons typically range from micropores (less than 2 nm) to mesopores (2-50 nm), but only micropores (<2 nm) contribute to pseudocapacitance. As pore size approaches the solvation shell size, solvent molecules are excluded and only unsolvated ions fill the pores (even for large ions), increasing ionic packing density and storage capability by faradaic intercalation.
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However, atoms on the surface of the adsorbent are not wholly surrounded by other adsorbent atoms and therefore can attract adsorbates. The exact nature of the bonding depends on the details of the species involved, but the adsorption process is generally classified as physisorption (characteristic of weak van der Waals forces) or chemisorption (characteristic of covalent bonding). It may also occur due to electrostatic attraction. Adsorption is present in many natural, physical, biological and chemical systems and is widely used in industrial applications such as heterogeneous catalysts, activated charcoal, capturing and using waste heat to provide cold water for air conditioning and other process requirements (adsorption chillers), synthetic resins, increasing storage capacity of carbide-derived carbons and water purification.
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Graphite is made of two-dimensional layers in which each carbon is covalently bonded to three other carbons; atoms in other layers are further away and are not nearest neighbours, giving a coordination number of 3. bcc structure Ions with coordination number six comprise the highly symmetrical "rock salt structure". For chemical compounds with regular lattices such as sodium chloride and caesium chloride, a count of the nearest neighbors gives a good picture of the environment of the ions. In sodium chloride each sodium ion has 6 chloride ions as nearest neighbours (at 276 pm) at the corners of an octahedron and each chloride ion has 6 sodium atoms (also at 276 pm) at the corners of an octahedron.
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Rio Avalon unreleased model The Carbon was announced on August 2, 2004. The first 500 Carbons were produced as a Limited Edition with a unique serial number (1-500) that was laser engraved into the polished steel (back) side of the player. The initial Carbon was silver with a 5 GB drive and retailed US $249.99, same as the iPod Mini with 4 GB. An off-white version called the Carbon Pearl was next, with a 5GB drive at first and then a 6 GB drive later as the price of Microdrives fell. This was followed by the 2.5 GB ce2100 (black) and ce2110 (light green) which offered reduced features and cost.
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To prevent this, a pantograph monitoring station can be used. At sustained high speeds (above ) friction can cause the contact strip to become red hot, which in turn can cause excessive arcing and eventual failure. In the UK, the pantographs (Brecknell Willis, Stone Faiveley etc.) of vehicles are raised by air pressure, and the graphite contact "carbons" create an air gallery in the pantograph head which release the air if a graphite strip is lost, activating the automatic drop device and lowering the pantograph to prevent damage. Newer electric traction units may use more sophisticated methods which detect the disturbances caused by arcing at the point of contact when the graphite strips are damaged.
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Intersystem crossing and associated spin- state orbitals of Fluorenylidene. The ground state is believed to be a bent triplet, with two orthogonal sp hybrid orbitals singly occupied by unpaired spins. One electron occupies an orbital of sigma symmetry in the plane of the rings, while the other occupies an orbital of pi symmetry, which interacts with the pi systems of the adjacent aromatic rings (delocalization into the rings is minimal, since zero-field parameter D is high). The zero field splitting parameters predict a bond angle greater than 135°, and since the ideal bond geometry for cyclopentane carbons is about 109°, considerable ring strain causes the methylene sigma bonds to be bent.
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Using Le Bel-van't Hoff rule, the aldohexose D-glucose, for example, has the formula (C·H2O)6, of which four of its six carbons atoms are stereogenic, making D-glucose one of 24=16 possible stereoisomers. In the case of glyceraldehydes, an aldotriose, there is one pair of possible stereoisomers, which are enantiomers and epimers. 1, 3-dihydroxyacetone, the ketose corresponding to the aldose glyceraldehydes, is a symmetric molecule with no stereo centers. The assignment of D or L is made according to the orientation of the asymmetric carbon furthest from the carbonyl group: in a standard Fischer projection if the hydroxyl group is on the right the molecule is a D sugar, otherwise it is an L sugar.
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For maximum sympathomimetic activity, a drug must have: # Amine group two carbons away from an aromatic group # A hydroxyl group at the chiral beta position in the R-configuration # Hydroxyl groups in the meta and para position of the aromatic ring to form a catechol which is essential for receptor binding The structure can be modified to alter binding. If the amine is primary or secondary, it will have direct action, but if the amine is tertiary, it will have poor direct action. Also, if the amine has bulky substituents, then it will have greater beta adrenergic receptor activity, but if the substituent is not bulky, then it will favor the alpha adrenergic receptors.
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The average C-N-C angle was claimed to be 119.2°, much closer to the 120° of the flat configuration than to the 111.8° of trimethylamine. This peculiarity was attributed to steric hindrance by the bulky isopropyl radicals. However, in 1998 X-ray diffraction analysis of the crystallized solid showed that the C3N core is actually pyramidal, with the N atom lying approximately 0.28 Å off the carbons' plane (whereas in trimethylamine the distance is about 0.45 Å). However the researchers could not rule out the crystal field effect as the cause of the asymmetry. The C-C-C planes of the isopropyl groups are slightly tilted (about 5°) relative to the threefold symmetry axis of the C3N core.
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Methylisocitrate lyase is used in the methylcitrate cycle, a modified version of the Krebs cycle that metabolizes propionyl coenzyme A instead of acetyl coenzyme A. The enzyme 2-methylcitrate synthase adds propionyl coenzyme A to oxaloacetate, yielding methylcitrate instead of citrate. But isomerizing methylcitrate to methylisocitrate and then subjecting it to MICL regenerates succinate, which proceeds as in the Krebs cycle, and pyruvate, which is easily metabolized by other pathways (e.g. decarboxylated to form acetyl coenzyme A and oxidized in the Krebs cycle). This allows catabolism of propionic acid—and, using beta oxidation, other fatty acids with odd numbers of carbons—without relying on coenzyme B12, a complex cofactor often used to metabolize propionate.
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If the bonding interactions outnumber the antibonding interactions, the MO is said to be bonding, whereas, if the antibonding interactions outnumber the bonding interactions, the molecular orbital is said to be antibonding. For example, butadiene has pi orbitals which are delocalized over all four carbon atoms. There are two bonding pi orbitals which are occupied in the ground state: π1 is bonding between all carbons, while π2 is bonding between C1 and C2 and between C3 and C4, and antibonding between C2 and C3. There are also antibonding pi orbitals with two and three antibonding interactions as shown in the diagram; these are vacant in the ground state, but may be occupied in excited states.
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However, activated carbon, at only US$4/kg for commodity carbon and US$15/kg for highly purified, specially selected supercapacitor carbon, remains much cheaper than the alternatives, which cost US$50/kg or more. Larger activated carbon electrodes are much cheaper than relatively small exotic carbon electrodes, and can remove just as much salt for a given current. The performance increase from novel carbons is insufficient to motivate their use at this point, especially since virtually all CDI applications under serious near-term consideration are stationary applications, where unit size is a relatively minor consideration. Nowadays, electrode materials based on redox-chemistry are more and more studied, such as sodium manganese oxide (NMO) and prussian blue analogues (PBA).
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For molecules in dynamic equilibrium such as the 2-norbornyl cation, nuclei within each set can also be transformed to one another through rearrangements with fast reaction rates. Since the proposed dynamic equilibrium of the classical ion proponents had very fast rates of rearrangement, the first NMR studies did not favor nor invalidate any of the three proposed structures. But by using solid-state NMR analysis, one can lower the temperature of the NMR experiment to and thus significantly slow down any rearrangement phenomena. Solid-state C NMR spectra of the 2-norbornyl cation shows that carbons 1 and 2 are in identical chemical environments, which is consistent only with the non-classical picture of the 2-norbornyl cation.
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Note that the cyclohexane ring of the starting unit is reduced during the transfer to module 1. The starting unit is then modified by a series of Claisen condensations with malonyl or methylmalonyl substrates, which are attached to an acyl carrier protein (ACP) and extend the polyketide by two carbons each. After each successive condensation, the growing polyketide is further modified according to enzymatic domains that are present to reduce and dehydrate it, thereby introducing the diversity of functionalities observed in rapamycin (figure 1). Once the linear polyketide is complete, L-pipecolic acid, which is synthesized by a lysine cycloamidase from an L-lysine, is added to the terminal end of the polyketide by an NRPS.
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Aldehyde deformylating oxygenases (ADO) () are a family of enzymes which catalyze the oxygenation of medium and long chain aldehydes to alkanes via the removal of a carbonyl group as formate. :n-aldehyde + O2 \+ 2 NADPH + H+ → (n-1)-alkane + formate + H2O + 2 NADP+ Aldehyde deformylating oxygenases are found in cyanobacteria as part of the alkane biosynthesis pathway. Their substrates are medium- to long-chain aldehydes formed from acyl-ACP by acyl- ACP reductases (), commonly of 16 and 18 carbons, but potentially as short as nonanal and decanal. Compared to other aldehyde decarbonylases, such as insect or plant aldehyde decarbonylase, cyanobacterial ADO is unusual in evolving formate rather than CO or CO2 and for residing in the cytosol.
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A double bond between two carbon atoms forces the remaining four bonds (if they are single) to lie on the same plane, perpendicular to the plane of the bond as defined by its π orbital. If the two bonds on each carbon connect to different atoms, two distinct conformations are possible, that differ from each other by a twist of 180 degrees of one of the carbons about the double bond. The classical example is dichloroethene , specifically the structural isomer ClHC=CHCl that has one chlorine bonded to each carbon. It has two conformational isomers, with the two chlorines on the same side or on opposite sides of the double bond's plane.
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Therefore, one has different configurational isomers depending on whether each hydroxyl is on "this side" or "the other side" of the ring's mean plane. Discounting isomers that are equivalent under rotations, there are nine isomers that differ by this criterion, and behave as different stable substances (two of them being enantiomers of each other). The most common one in nature (myo-inositol) has the hydroxyls on carbons 1, 2, 3 and 5 on the same side of that plane, and can therefore be called cis-1,2,3,5-trans-4,6-cyclohexanehexol. And each of these cis-trans isomers can possibly have stable "chair" or "boat" conformations (although the barriers between these are significantly lower than those between different cis-trans isomers).
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The loading module starts out the biosynthetic pathway by tethering to an acyl group of the acyl carrier protein (ACP).This starter unit then gets carried to module 1 where a malonyl group gets added on by malonyl-CoA followed by the β-carbonyl getting reduced to a hydroxyl group by a ketoreductase (KR) enzyme that then undergoes dehydration to a trans double bond by a dehydratase enzyme (DH). In this first module, there is an enoyl reductase enzyme (ER), but it is inactive. This chain then goes through two more elongations in module 2 and module 3 which are similar to module 1, only they result in cis double bonds at their respective β-carbons.
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The roots of CarboTech AC GmbH connect to the early 1938 when the foundation of the bituminous coal mining society (Steinkohlenbergbauvereins) has taken place. After World War II, the Bergwerksverband GmbH began setting up experimental facilities for the production and development of activated carbons from bituminous coal. In 1956, a large-scale pilot plant was commissioned on the site of the former Queen Elisabeth coal mine (Zeche Königin Elisabeth) in Essen and in 1958, foundation for the Bergbau-Forschung GmbH Archive NRW as the research institute of bituminous coal mining was established. Later in the 1970s, the development of Carbon Molecular Sieves took place and this enabled the production of 99.999% pure nitrogen and hydrogen by Bergbau-Forschung GmbH.
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The Energos system includes a close coupled combustion stage which, as configured, uses all the syngas in the combustion stage. It is thus not able to produce syngas for external use and therefore sometimes categorized as two-stage combustion. The process enables improved control of the combustion to minimise the formation of combustion related emissions such as oxides of nitrogen (NOx), Carbon Monoxide (CO) and Total Organic Carbons (TOC). Operating plants achieve average annual NOx emissions of 25 – 30% of the EU limit using just process control and without the need for either Selective Non Catalytic Reduction (SNCR) or Selective Catalytic Reduction (SCR), whilst at the same time achieving very low CO and TOC emissions.
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Periodic acid Periodic acid–Schiff (PAS) is a staining method used to detect polysaccharides such as glycogen, and mucosubstances such as glycoproteins, glycolipids and mucins in tissues. The reaction of periodic acid oxidizes the vicinal diols in these sugars, usually breaking up the bond between two adjacent carbons not involved in the glycosidic linkage or ring closure in the ring of the monosaccharide units that are parts of the long polysaccharides, and creating a pair of aldehydes at the two free tips of each broken monosaccharide ring. The oxidation condition has to be sufficiently regulated so as to not oxidize the aldehydes further. These aldehydes then react with the Schiff reagent to give a purple-magenta color.
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Additionally, due to PIMs affinity for small gases and ability to form self-standing films they are actively being investigated as a membrane material and adsorbent for industrial separation processes such as gas separation and carbon dioxide capture. PIM membranes are also heavily investigated due to their contribution in the revision of the 2008 upper bounds of performance by Robeson, an important parameter in membrane gas separation stating that the permeability must be sacrificed for selectivity. Specifically active areas of PIM membrane research include, enhancing permeability, decreasing aging, and tailoring selectivity. PIMs are also used to create mixed matrix membranes with a variety of material such as inorganic materials, metal-organic frameworks, and carbons.
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In theory, there are 51 structural isomers of coronene that have six fused benzene rings in a cyclic sequence, with two edge carbons shared between successive rings. All of them must be non-planar and have considerable higher bonding energy (computed to be at least 130 kcal/mol) than coronene; and, as of 2002, none of them had been synthesized.Jan Cz. Dobrowolski (2002): "On the belt and Moebius isomers of the coronene molecule". Journal of Chemical Information and Computer Science, volume 42, issue 3, pages 490–499 Other PAHs that might seem to be planar, considering only the carbon skeleton, may be distorted by repulsion or steric hindrance between the hydrogen atoms in their periphery.
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The resultant Si-C π-interaction agreed with calculated bond lengths, as well as general understanding of the cAAC ligands as good π-acceptors relative to NHC ligands. From this, the central silicon atom was proposed to act as a π-electron donor, while the carbene carbons acted as σ-electron donors. Calculation of the first and second proton affinities (PA(1) = 272.2 kcal/mol, PA(2) = 186.7 kcal/mol) of the complex supported the identity of the structure as a Si0 silylone than a SiII silylene, particularly due to the large value of the second proton affinity. Finally, Bader charge analysis of the complex agreed with those predicted from NBO analysis.
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It has been shownAbsence of SN1 Involvement in the Solvolysis of Secondary Alkyl Compounds, T. J. Murphy, J. Chem. Educ.; 2009; 86(4) pp 519-24; (Article) doi: 10.1021/ed041p678 that except in uncommon (but predictable cases) primary and secondary substrates go exclusively by the SN2 mechanism while tertiary substrates go via the SN1 reaction. There are two factors which complicate determining the mechanism of nucleophilic substitution reactions at secondary carbons: 1) Many reactions studied are solvolysis reactions where a solvent molecule–often an alcohol, is the nucleophile. While still a second order reaction mechanistically, the reaction is kinetically first order as the concentration of the nucleophile–the solvent molecule, is effectively constant during the reaction.
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One application of carbide- derived carbons is as active material in electrodes for electric double layer capacitors which have become commonly known as supercapacitors or ultracapacitors. This is motivated by their good electrical conductivity combined with high surface area, large micropore volume, and pore size control that enable to match the porosity metrics of the porous carbon electrode to a certain electrolyte. In particular, when the pore size approaches the size of the (desolvated) ion in the electrolyte, there is a significant increase in the capacitance. The electrically conductive carbon material minimizes resistance losses in supercapacitor devices and enhances charge screening and confinement, maximizing the packing density and subsequent charge storage capacity of microporous CDC electrodes.
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He was among the first to realise and exploit the power of statistical mechanical treatments for the adsorption of gases and liquids in nano-porous materials (such as carbons, silicas and metal-organic framework materials). Such adsorption processes are central to many separation and purification processes, as well as catalysis. The density functional theory method developed by Gubbins and coworkers is now universally used in analysing adsorption isotherms to calculate pore size distributions and porosity of nano-porous materials. More recently he has made major contributions to the characterisation of amorphous porous materials through application of statistical mechanical methods, and to the understanding of diffusion processes and chemical reactions in these materials.
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Helium-3 nuclear magnetic resonance (3He-NMR) is an analytical technique used to identify helium-containing compounds. Because a helium atom, or even two helium atoms, can be encased in fullerene-like cages, the nuclear magnetic resonance spectroscopy of this element can be a sensitive probe for changes of the carbon framework around it. Using carbon-13 NMR to analyze fullerenes themselves is complicated by so many subtle differences among the carbons in anything but the simplest, highly-symmetric structures. The technique is limited by the need to use the rare helium-3 isotope: the vast majority of naturally occurring helium is helium-4, which does not have suitable magnetic properties for NMR detection.
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In chemistry, vinylene (also ethenylene or 1,2-ethenediyl) is a divalent functional group (a part of a molecule) with formula −CH=CH−; namely, two carbons, each connected to the other by a double bond, to an hydrogen atom by a single bond, and to the rest of the molecule by another single bond. This group can be viewed as a molecule of ethene (ethylene, H2C=CH2) with an hydrogen removed from each carbon; or a vinyl group −CH=CH2 with one hydrogen removed from the terminal carbon. It should not be confused with the vinylidene group =C=CH2 or >C=CH2. A vinylene unit attached to two distinct atoms other than hydrogen (namely R−CH=CH−R') is a source of cis-trans isomerism.
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Enzymatic activity of HADHB in beta-oxidation This gene encodes the beta subunit of the mitochondrial trifunctional protein, a catalyst of mitochondrial beta-oxidation of long chain fatty acids. The HADHB protein catalyzes the final step of beta- oxidation, in which 3-ketoacyl CoA is cleaved by the thiol group of another molecule of Coenzyme A. The thiol is inserted between C-2 and C-3, which yields an acetyl CoA molecule and an acyl CoA molecule, which is two carbons shorter. The encoded protein can also bind RNA and decreases the stability of some mRNAs. The genes of the alpha and beta subunits of the mitochondrial trifunctional protein are located adjacent to each other in the human genome in a head-to-head orientation.
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Fatty acids bound to coenzyme A allow penetration into mitochondria. Once inside the mitochondrion, the bound fatty acids are used as fuel in cells predominantly through beta oxidation, which cleaves two carbons from the acyl-CoA molecule in every cycle to form acetyl-CoA. Acetyl-CoA enters the citric acid cycle, where it undergoes an aldol condensation with oxaloacetate to form citric acid; citric acid then enters the tricarboxylic acid cycle (TCA), which harvests a very high energy yield per carbon in the original fatty acid. Biochemical pathway of ketone synthesis in the liver and utilization by organs Acetyl-CoA can be metabolized through the TCA cycle in any cell, but it can also undergo ketogenesis in the mitochondria of liver cells.
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Industry can use oil shale as a fuel for thermal power-plants, burning it (like coal) to drive steam turbines; some of these plants employ the resulting heat for district heating of homes and businesses. In addition to its use as a fuel, oil shale may also serve in the production of specialty carbon fibers, adsorbent carbons, carbon black, phenols, resins, glues, tanning agents, mastic, road bitumen, cement, bricks, construction and decorative blocks, soil-additives, fertilizers, rock-wool insulation, glass, and pharmaceutical products. However, oil shale use for production of these items remains small or only in its experimental stages.Dyni (2010), p. 98 Some oil shales yield sulfur, ammonia, alumina, soda ash, uranium, and nahcolite as shale-oil extraction byproducts.
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He is afflicted with > rheumatism and his speech was delivered partly as he kneeled before the jury > in a manful effort to stand and partly from his chair, when his exertions > overcame him and he was obliged to seat himself."Collard Guilty: Murderer of > Gip Railey Gets a Life Sentence" The Wapanucka Press, October 22, 1903 The workload of the new Criminal Court of Appeals was immense. Upon its creation, the Court had inherited pending criminal appeals from the Court of Appeals of the Indian Territory and the Supreme Court of Oklahoma Territory. Using typewriters, carbons, and onionskin papers, the Court on average issued published opinions in over 300 cases annually for several years after statehood, and unpublished summary opinions in many more.
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As mentioned in the background section, one advantage that peptides has over carbon as nanosize building blocks is that they have almost limitless chemical functionality compared with the very chemical interactions that carbons can perform due to their nonreactiveness. Furthermore, CNTs exhibits strong hydrophobicity which results in a tendency to clump in aqueous solutions and therefore has limited solubility; their electrical properties are also affected by humidity, and the presence of oxygen, N2O and NH3. It is also difficult for to produce CNTs with uniform properties and this pose serious drawbacks as for commercial purposes the reproducibility of precise structural properties is a key concern. Lastly, CNTs are expensive with prices in the range of hundreds of dollars per gram, rendering most applications of them commercially unviable.
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United States v. Washam (2002) 312 F.3d 926, 930 was an appellate decision for the eighth judicial circuit in which it was considered whether the drug 1,4-butanediol (1,4-B) was a controlled substance analogue in the United States. The controlled drug which it was alleged 1,4-B was substantially similar to was gamma-hydroxybutyrate (GHB). 120px 1,4-B 120px GHB In this case the court ruled that 1,4-B was substantially similar to GHB, on the grounds that (i) “1,4-Butanediol and GHB are both linear compounds containing four carbons and that there is only one difference between the substances on one side of their molecules”, and (ii) that 1,4-B is metabolized into GHB by the body and so produces substantially similar physiological effects.
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Methods which have been employed for the preparation of 1,2,3,4-cyclohexanetetrols include: reduction or hydrogenation of (1) cyclohexenetetrols, (2) tri-hydroxycyclohexanones, (3) pentahydroxycyclohexanones (inososes), (4) hydroxylated aromatics, or (5) hydroxylated quinones; the (6) hydrogenolysis of dibromocyclohexanetetrols; the (7) hydration of diepoxycyclohexanes; and the hydroxylation of (8) cyclohexadienes or (9) cyclohexenediols. In 2007, Peter Valente and others described the preparation of achiral 1,4/2,3-cyclohexanetetrol (toxocarol) from 2,3-dioxabicyclo[2.2.2]oct-5-ene, a cyclohexene with a peroxide bridge (–O–O–) replacing hydrogens in carbons 3 and 6. The previous route was reduction of the peroxide brige to yield 3α,6α-dihydroxy cyclohexene, followed by di-hydoxylation of the double bond; which yielded a mixture of the 1,4/2,3 and 1,2,3,4/0 isomers.
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According to the German Patent bureau, the industrial synthesis of diazinon is as follows: :β-isobutyrylaminocrotonic acid amine was cyclized with NaOR (R is either a hydrogen or aliphatic chain of 1 to 8 carbons) in a mixture of 0 to 100% by weight of water and an alcohol having 1 to 8 carbon atoms, above 90°C (but below the boiling point of the mixture used). Sodium pyrimidinolate was precipitated out in an inert solvent, such as benzene, with simultaneous removal of the water formed. The potassium salt is then reacted with diethylthiophosphoryl chloride by heating for several hours. When the reaction finished, the potassium chloride formed was washed with water and the solvent was removed under reduced pressure leaving diazinon.
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There are several mechanisms by which passing a current through the electrochemical cell can encourage pollutant desorption. Ions generated at the electrodes can change local pH conditions in the divided cell which affect the adsorption equilibrium and have been shown to promote desorption of organic pollutants such as phenols from the carbon surface. Other mechanisms include reactions between the ions generated and the adsorbed pollutants resulting in the formation of a species with a lower adsorptive affinity for activated carbon that subsequently desorb, or the oxidative destruction of the organics on the carbon surface. It is agreed that the main mechanisms are based on desorption induced regeneration as electrochemical effects are confined to the surface of the porous carbons so cannot be responsible for bulk regeneration.
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Humans have 57 putatively active CYP genes and 58 CYP pseudogenes of which only a few are polyunsaturated fatty acid (PUFA) epoxygenases, i.e. enzymes with the capacity to attach atomic oxygen (see Allotropes of oxygen#Atomic oxygen) to the carbon-carbon double bonds of long chain PUFA to form their corresponding epoxides. These CYP epoxygenases represent a family of enzymes that consists of several members of the CYP1 and CYP2 subfamilies. The metabolism of the straight chain 20-carbon polyunsaturated fatty eicosatetraenoic acid, arachidonic acid, by certain CYP epoxygenases is a good example of their action. Arachidonic acid has 4 cis-configured double bonds (see Cis–trans isomerism) located between carbons 5-6, 8-9, 11-12, and 14-15 Double bonds.
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Normally, carbon is tetravalent, while oxygen is divalent, and in most oxocarbons (as in most other carbon compounds) each carbon atom may be bound to four other atoms, while oxygen may be bound to at most two. Moreover, while carbon can connect to other carbons to form arbitrarily large chains or networks, chains of three or more oxygens are rarely if ever observed. Thus the known electrically neutral oxocarbons generally consist of one or more carbon skeletons (including cyclic and aromatic structures) connected and terminated by oxide (-O-, =O) or peroxide (-O-O-) groups. Carbon atoms with unsatisfied bonds are found in some oxides, such as the diradical C2O or :C=C=O; but these compounds are generally too reactive to be isolated in bulk.
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The now 8-carbon chain then goes through another extension by malonyl-CoA in module 4, followed by a reduction by a KR domain. In module 5, an elongation is performed by methylmalonyl-CoA in which the chain undergoes another reduction to a hydroxyl group. The polyketide intermediate is then passed on to module 6 where another malonyl-CoA is loaded, and here, a reduction, then dehydration of the β-carbon form the final double bond of the linear chain. The growing chain is almost completely synthesized at this point and is taken through two elongations of 2 carbons in modules 7 and 8, each of which contain KRs to produce the final two hydroxyl groups in the alkyl chain.
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With proton-noise decoupling, in which most spectra are run, a noise decoupler strongly irradiates the sample with a broad (approximately 1000 Hz) range of radio frequencies covering the range (such as 100 MHz for a 23,486 gauss field) at which protons change their nuclear spin. The rapid changes in proton spin create an effective heteronuclear decoupling, increasing carbon signal strength on account of the nuclear Overhauser effect (NOE) and simplifying the spectrum so that each nonequivalent carbon produces a singlet peak. The relative intensities are unreliable because some carbons have a larger spin-lattice relaxation time and others have weaker NOE enhancement. In gated decoupling, the noise decoupler is gated on early in the free induction delay but gated off for the pulse delay.
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Bernhard Witkop (May 9, 1917 in Freiburg, Baden - November 22, 2010 in Chevy Chase, Maryland) was a German-born American organic chemist who worked for the National Institutes of Health (NIH) for 37 years. During those years, Dr. Witkop – along with his recruit, the late Dr. John Daly, and others – discovered the NIH shift, a term describing the movement of hydrogen, deuterium or tritium to adjacent carbons on aromatic rings during oxidation, a process key in developing many therapies. He also helped to develop selective methods for the non-enzymatic cleavage of proteins, which enabled the sequencing of amino acids in proteins as large as immunoglobulin, a method later used in the production of human insulin. Dr. Witkop also helped pioneer the NIH Visiting Fellow Program.
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4'-Methyl-α-pyrrolidinohexiophenone (MPHP) is a stimulant compound which has been reported as a novel designer drug. It is closely related to pyrovalerone, being simply its chain-lengthened homologue. In the pyrrolidinophenone series, stimulant activity is maintained so long as the positions of the aryl, ketone and pyrrolidinyl groups are held constant, while the alkyl backbone can be varied anywhere between three and as many as seven carbons, with highest potency usually seen with the pentyl or isohexyl backbone, and a variety of substituents are tolerated on the aromatic ring. In 2010 a group of researchers from the Institute of Forensic Medicine, University Hospital Jena, Germany concluded that MPHP can lead to serious poisoning with toxic liver damage and rhabdomyolysis.
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Murray et al., p. 19. The peptide bond has two resonance forms that contribute some double-bond character and inhibit rotation around its axis, so that the alpha carbons are roughly coplanar. The other two dihedral angles in the peptide bond determine the local shape assumed by the protein backbone.Murray et al., p. 31. The end with a free amino group is known as the N-terminus or amino terminus, whereas the end of the protein with a free carboxyl group is known as the C-terminus or carboxy terminus (the sequence of the protein is written from N-terminus to C-terminus, from left to right). The words protein, polypeptide, and peptide are a little ambiguous and can overlap in meaning.
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The closed or cyclic form of a pentose is created when the carbonyl group interacts with an hydroxyl in another carbon, turning the carbonyl into a hydroxyl and creating an ether bridge –O– between the two carbons. This intramolecular reaction yields a cyclic molecule, with a ring consisting of one oxygen atom and usually four carbon atoms; the cyclic compounds are then called furanoses, for having the same rings as the cyclic ether tetrahydrofuran. Library of Congress catalog 66-25695 The closure turns the carboxyl carbon into a chiral center, which may have any of two configurations, depending on the position of the new hydroxyl. Therefore, each linear form can produce two distinct closed forms, identified by prefixes "α" and "β".
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Unit cell of B4C. The green sphere and icosahedra consist of boron atoms, and black spheres are carbon atoms. Fragment of the B4C crystal structure. Boron carbide has a complex crystal structure typical of icosahedron-based borides. There, B12 icosahedra form a rhombohedral lattice unit (space group: Rm (No. 166), lattice constants: a = 0.56 nm and c = 1.212 nm) surrounding a C-B-C chain that resides at the center of the unit cell, and both carbon atoms bridge the neighboring three icosahedra. This structure is layered: the B12 icosahedra and bridging carbons form a network plane that spreads parallel to the c-plane and stacks along the c-axis. The lattice has two basic structure units – the B12 icosahedron and the B6 octahedron.
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General chemical structure of PCDFs, where 2 ≤ n+m ≤ 8 congeners that are toxicologically of most relevance More thorough treatise of all groups with similar actions and binding to aryl hydrocarbon reeceptor is given in Dioxins and dioxin-like compounds. Polychlorinated dibenzofurans (PCDFs) are a family of organic compounds with one or several of the hydrogens in the dibenzofuran structure replaced by chlorines. For example, 2,3,7,8-tetrachlorodibenzofuran (TCDF) has chlorine atoms substituted for each of the hydrogens on the number 2, 3, 7, and 8 carbons (see structure in the upper left corner of the second image). Polychlorinated dibenzofurans with chlorines at least in positions 2,3,7 and 8 are much more toxic than the parent compound dibenzofurane, with properties and chemical structures similar to polychlorinated dibenzodioxins.
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The gas may then be desorbed when subjected to higher temperatures and either combusted to do work or in the case of hydrogen gas extracted for use in a hydrogen fuel cell. Gas storage in activated carbons is an appealing gas storage method because the gas can be stored in a low pressure, low mass, low volume environment that would be much more feasible than bulky on-board pressure tanks in vehicles. The United States Department of Energy has specified certain goals to be achieved in the area of research and development of nano-porous carbon materials. All of the goals are yet to be satisfied but numerous institutions, including the ALL-CRAFT program, are continuing to conduct work in this promising field.
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The most important factor in influencing homoaromatic character is the addition of a single homoconjugate linkage into the parent aromatic compound. The location of the homoconjugate bond is not important as all homoaromatic species can be derived from aromatic compounds that possess symmetry and equal bond order between all carbons. The insertion of a homoconjugate linkage perturbs the π-electron density an amount δβ, which depending on the ring size, must be greater than 0 and less than 1, where 0 represents no perturbation and 1 represents total loss of aromaticity (destabilization equivalent to the open chain form). It is believed that with increasing ring size, the resonance stabilization of homoaromaticity is offset by the strain in forming the homoconjugate bridge.
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Tween 20-Au NPs are rapid, efficient and selective in capturing Hg2+ in high salt water concentration when the gold NPs catalyze the citrate ion induced reduction of Hg2+ to Hg0.F. S. Zhang, J. O. Nriagu, and H. Itoh, "Mercury removal from water using activated carbons derived from organic sewage sludge," Water Research, vol. 39, no. 2–3, pp. 389–395, 2005. ICP-MS is used to quantify the Hg2+ concentration to determine the level of elimination efficiency. Figure 3 shows an illustration process of the nano trap filtration process. The use of nanomaterials in removing the mercury from water is advantageous because of the high surface area to volume ratio and the fact that they are easily chemically functionalized.
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Sera then appears in the form of a robot to Mega Man and states that she did not execute the Carbon Reinitialization Program but has, instead, been waiting for Mega Man's arrival to challenge him in hopes that by defeating him she would prove that their master liked her more. In battle, Gatz tries to aid Mega Man by attacking Sera's logic circuits, but dies in the attempt. As Mega Man defeats Sera, Yuna arrives at the scene reminding Sera that it is not their Master's wish for her to die. Sera awakes in Yuna's real body and decides to help Yuna protect the Carbons from the machines that are being activated in Terra due to an old system Master tried to stop.
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Many dicarbaboranes exist as isomers that differ in the relative location of the carbon centers. In addition to the three previously mentioned icosahedral C2B10H12 compounds, isomerism is also found in some smaller closo-carborane systems, e.g., 1,2- and 1,6-C2B4H6, 2,3- and 2,4-C2B5H7, 1,2- and 1,6-C2B6H8, and 2,3- and 2,4-C2B5H7, as well as in open-cage carboranes such as 2,3- and 2,4-C2B4H8 and 1,2 and 1,3-C2B9H13. In general, isomers having non-adjacent cage carbon atoms are more thermally stable than those with adjacent carbons, so that heating tends to induce mutual separation of the carbon atoms in the framework. This is illustrated by the thermal isomerization of 1,2- to 1,6-C2B4H6 and of 1,2- to 1,7-C2B10H12.
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Another point of diversion between these two syntheses is the number of carbons separating the keto-auxiliary group from the chiral center at C7. This group was separated by one carbon from C7 in the first total synthesis, so the keto- auxiliary moiety could be converted to a carboxylic acid, in anticipation of addition of the amino alcohol immediately thereafter. In this synthesis, this keto-auxiliary group is directly adjacent to C7, necessitating a one carbon homologation, before construction of the thiazoline ring. This was achieved through reductive bond cleavage of the auxiliary group to a primary alcohol and oxidation to the corresponding aldehyde, Wittig reaction using an ylide carrying a methoxy group to produce an enol ether, hydrolysis to the aldehyde and finally oxidation to produce the carboxylic acid.
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This is a situation unlike that in covalent crystals, where covalent bonds between specific atoms are still discernible from the shorter distances between them, as measured via such techniques as X-ray diffraction. Ionic crystals may contain a mixture of covalent and ionic species, as for example salts of complex acids such as sodium cyanide, NaCN. X-ray diffraction shows that in NaCN, for example, the bonds between sodium cations (Na+) and the cyanide anions (CN−) are ionic, with no sodium ion associated with any particular cyanide. However, the bonds between C and N atoms in cyanide are of the covalent type, so that each carbon is strongly bound to just one nitrogen, to which it is physically much closer than it is to other carbons or nitrogens in a sodium cyanide crystal.
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This catalytic CVD process has been used as an industrially available mass production method, both substrate and floating catalyst processes. Present CCVD process has been expecting to grow the wide range of carbon nanotubes by controlling the growth site as well as their nanostructure. His main research interests are science and applications of "nanocarbons" such as carbon nanotubes, and he has contributed to development of new composites and high-performance energy storage devices such as lithium ion battery, electric double layer capacitor, and fuel cell, based on such structure controlled advanced carbons. Since 1990, he is a professor of Education and training of electrical and electronics engineers, and now is also the Director of Institute of Carbon Science & Technology, both at Shinshu University. He is one of the international advisory members of “CARBON” journal.
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In a Fischer projection, all horizontal bonds are meant to be slanted toward the viewer. Molecules with a simple tetrahedral geometry can be easily rotated in space, so that this condition is met (see figures). For instance, a monosaccharide with three carbon atoms (triose), such as the D-Glyceraldehyde depicted above has a tetrahedral geometry, with C2 at its center, and can be rotated in space so that the carbon chain is vertical with C1 at the top, and the horizontal bonds connecting C2 with -H and -OH are both slanted toward the viewer. However, when creating a Fischer projection for a monosaccharide with more than three carbons, there's no way to orient the molecule in space so that all horizontal bonds will be slanted toward the viewer.
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Tetrahedron Lett. 2003, 44, 3569-3572. Structure 5 was desymmetrized through an enzymatic transesterification process, using an immobilized lipase PS 30 enzyme to give structure 6, which was formed with a 99% enantiomeric excess.Mehta, G.; Islam, K. Enantioselective Total Synthesis of (−)-epoxyquinols A and B. Novel, convenient access to chiral epoxyquinone building blocks through enzymatic desymmetrization. Tetrahedron Lett. 2004, 45, 3611-3615. :File:IntegrasoneSynthesis1.gif The stereochemistry of the hydroxyl group at carbon 6 in the final integrasone molecule (3) was determined by reduction, which was both regio and stereo selective due to the directing effects of the primary hydroxyl group (carbon 8) and the epoxide ring (carbons 4 and 5). The hydroxy group on carbon 8 is then selectively protected with as the triethylsilyl (TES) ether to give structure 8.
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He proposed alternative methodologies for the synthesis of MeBmt, a variety of amino acid present in cyclosporin-A and of FK-506k, a 23-membered macrolide with 14-asymmetric carbons, which are reported to be noteworthy achievements in the field of asymmetric synthesis. His work also covered the synthesis of depsipeptides such as Jaspamide and Geodiamolides and macrolides, namely Zearalenone, Rifamycin-S, Rhizoxin and Rapamycin. Rao is the pioneer of Chiral synthesis and technology in India and is known to have synthesized compounds of high structural diversity like Coriolic acid, Dimorphicolic acid, β-Lactam antibiotics, Azamacrolides, Camptothecin, Andrimid and Chrysanthemic acid. His work on K-13 has been adopted for the synthesis of Vancomycin and has helped in the synthesis of vancomycinic acid and the biphenyl segment of Vancomycin.
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STM image of surfaces at the edge of a 1 μm thick layer of ta-C "diamond-like" coating on 304 stainless steel after various durations of tumbling in a slurry of 240 mesh SiC abrasive. The first 100 min shows a burnishing away from the coating of an overburden of soft carbons than had been deposited after the last cycle of impacts converted bonds to sp3. On the uncoated part of the sample, about 5 μm of steel were removed during subsequent tumbling while the coating completely protected the part of the sample it covered. Within the "cobblestones", nodules, clusters, or "sponges" (the volumes in which local bonding is sp3) bond angles may be distorted from those found in either pure cubic or hexagonal lattices because of intermixing of the two.
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Another potential complication results from the presence of large one bond J-coupling constants between carbon and hydrogen (typically from 100 to 250 Hz). In order to suppress these couplings, which would otherwise complicate the spectra and further reduce sensitivity, carbon NMR spectra are usually proton decoupled to remove the signal splitting. Couplings between carbons can be ignored due to the low natural abundance of 13C. Hence in contrast to typical proton NMR spectra which show multiplets for each proton position, carbon NMR spectra show a single peak for each chemically non-equivalent carbon atom. In further contrast to 1H NMR, the intensities of the signals are not normally proportional to the number of equivalent 13C atoms and are instead strongly dependent on the number of surrounding spins (typically 1H).
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If the double bond of an acyclic mono-ene is not the first bond of the chain, the name as constructed above still does not completely identify the compound, because of cis-trans isomerism. Then one must specify whether the two single C–C bonds adjacent to the double bond are on the same side of its plane, or on opposite sides. For monoalkenes, the configuration is often indicated by the prefixes cis- (from Latin "on this side of" or trans- ("across", "on the other side of") before the name, respectively; as in cis-2-pentene or trans-2-butene. The difference between cis- and trans- isomers More generally, cis-trans isomerism will exist if each of the two carbons of in the double bond has two different atoms or groups attached to it.
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Two numbers or sets of letters indicate a dyadic homopolymer formed from two monomers: one diamine and one dicarboxylic acid. The first number indicates the number of carbons in the diamine. The two numbers should be separated by a comma for clarity, but the comma is often omitted. :PA or Nylon 6,10 (or 610) : [NH−(CH2)6−NH−CO−(CH2)8−CO]n made from hexamethylenediamine and sebacic acid; For copolymers the comonomers or pairs of comonomers are separated by slashes: :PA 6/66 : [NH-(CH2)6−NH−CO−(CH2)4−CO]n−[NH−(CH2)5−CO]m made from caprolactam, hexamethylenediamine and adipic acid ; :PA 66/610 : [NH−(CH2)6−NH−CO−(CH2)4−CO]n−[NH−(CH2)6−NH−CO−(CH2)8−CO]m made from hexamethylenediamine, adipic acid and sebacic acid.
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450px The transition state model for a six-membered oxocarbenium ring was proposed earlier in 1992 by Woods et al. The general strategy for determining the stereochemistry of a nucleophilic addition to a six-membered ring follows a similar procedure to the case of the five-membered ring. The assumption that one makes for this analysis is that the ring is in the same conformation as cyclohexene, with three carbons and the oxygen in a plane with the two other carbon atome puckered out of the plane, with one above and one below (see the figure to the right). Based on the substituients present on the ring, the lowest energy conformation is determined, keeping in mind steric and steroelectronic effects (see the section below for a discussion of stereoelectronic effects in oxocarbenium rings).
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The synthesis developed by the Bachmann group started from Butenand's ketone - the 7-methoxy structural analog of 1,2,3,4-tetrahydrophenanthren-1-one - and which can be readily prepared from 1,6-Cleve's acid. The approach was based on well- established transformations like the Claisen condensation, the Reformatsky reaction, the Arndt–Eistert reaction, and the Dieckmann condensation. Nicolaou described this preparation as ending the era preceding the post-World War II work of Robert Burns Woodward that introduced enantioselective synthesis; in this synthesis, a mixture of stereoisomers were prepared and then resolved, and the choice of target was partly because of the existence of only two chiral carbons and hence only four stereoisomers. 700px The overall yield of the synthesis was 2.7% based on a twenty-step process starting from Cleve's acid.
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IBX is also available as silica gel or polystyrene bound IBX. In many applications, IBX is replaced by Dess–Martin periodinane which is more soluble in common organic solvents. A sample reaction is an IBX oxidation used in the total synthesis of eicosanoid: More and Finney and Van Arman have demonstrated that common organic solvents are suitable for many IBX oxidations, despite its low solubility, and in fact may simplify product purification. :IBX oxidation of alcohol to aldehyde key data: a) IBX, DMSO, THF, 4h, 94% chemical yield (Mohapatra, 2005) In 2001, K. C. Nicolaou and co- workers published a series of papers in the Journal of the American Chemical Society demonstrating, among other transformations, the use of IBX to oxidize primary and secondary benzylic carbons to aromatic aldehydes and ketones, respectively.
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The examples in textbooks of secondary substrates going by the SN1 mechanism invariably involve the use of bromide (or other good nucleophile) as the leaving group have confused the understanding of alkyl nucleophilic substitution reactions at secondary carbons for 80 years[3]. Work with the 2-adamantyl system (SN2 not possible) by Schleyer and co-workers,The 2-Adamantyl System, a Standard for Limiting Solvolysis in a Secondary Substrate J. L. Fry, C. J. Lancelot, L. K. M. Lam, J. M Harris, R. C. Bingham, D. J. Raber, R. E. Hill, P. v. R. Schleyer, J. Am. Chem. Soc.,; 1970; 92, pp 1240-42 (Article); doi: 10.1021/ja00478a031 the use of azide (an excellent nucleophile but very poor leaving group) by Weiner and Sneen,A Clarification of the Mechanism of Solvolysis of 2-Octyl Sulfonates.
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Numbering of the heptazine atoms The various tautomeric forms differ in the position of the hydrogen atoms. Each oxygen is connected to one of the corner carbons; it may be bonded to a hydrogen, forming a hydroxy group; or may have a double bond to the carbon, in which case the hydrogen is bonded to one of several adjacent nitrogen atoms. The trihydroxy tautomer is one of several that have more than one planar conformational isomer. In this case, there is a symmetric one, with all three hydroxyls bent in the same direction around the ring, and an asymmetric one, with one of them bent in the opposite direction compared to the other two. Calculations show that the symmetric form 1,4,7-trihydro-2,5,8-trioxo is the most stable.
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Primarily, the food source of Z. cellare is ethanol from the process of barrel aging, but upon further investigation it was found that Z. cellare can survive, and even thrive, on much more. Chlebicki and Majewska (2010) discovered that this fungus can utilize any volatile, oxygen-containing organic compound including various other alcohols, esters, acetic acids, acetylaldehydes, as well as formaldehyde and thymol. Out of these compounds, it is found that alcohols and acids that are three to five carbons in length are preferred by this organism, but will gladly feed on any length of the former compounds if need be. As well, concentration is not a crucial factor by any means as the typical laboratory air concentration for volatile, organic compounds is enough for Z. cellare to grow.
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Seenithurai & Chai 2020 found that larger cyclo[n]carbons [up to 100 carbon atoms] exhibit polyradical character and report linear carbon chains (l-CC[n]) as well as cyclic carbon chain or cyclo[n] carbon (c-CC[n]), where n=10-100. For all the cases investigated, l-CC[n] and c-CC[n] are ground-state singlets, and c-CC[n] are energetically more stable than l-CC[n]. The electronic properties of l-CC[n] and c-CC[n] display peculiar oscillation patterns for smaller values of n, followed by monotonic changes for larger values of n. For the smaller carbon chains, odd-numbered l-CC[n] are more stable than the adjacent even- numbered ones, and c-CC[4m+2]/c-CC[4m] (where m are positive integers) are more/less stable than the adjacent odd-numbered ones.
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Retroprogesterone, also known as 9β,10α-progesterone or as 9β,10α-pregn-4-ene-3,20-dione, is a progestin which was never marketed. It is a stereoisomer of the naturally occurring progestogen progesterone, in which the hydrogen atom at the 9th carbon is in the α-position (below the plane) instead of the β-position (above the plane) and the methyl group at the 10th carbon is in the β-position instead of the α-position. In other words, the atom positions at the two carbons have been reversed relative to progesterone, hence the name retroprogesterone. This reversal results in a "bent" configuration in which the plane of rings A and B is orientated at a 60° angle below the rings C and D. This configuration is ideal for interaction with the progesterone receptor, with retroprogesterone binding with high affinity to this receptor.
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The mechanism of the Michaelis–Arbuzov reaction The Michaelis–Arbuzov reaction is initiated with the SN2 attack of the nucleophilic phosphorus species (1 - A phosphite) with the electrophilic alkyl halide (2) to give a phosphonium salt as an intermediate (3). These intermediates are occasionally stable enough to be isolated, such as for triaryl phosphites which do not react to form the phosphonate without thermal cleavage of the intermediate (200°C), or cleavage by alcohols or bases. The displaced halide anion then usually reacts via another SN2 reaction on one of the R1 carbons, displacing the oxygen atom to give the desired phosphonate (4) and another alkyl halide (5). This has been supported by the observation that chiral R1 groups experience inversion of configuration at the carbon center attacked by the halide anion. This is what is expected of an SN2 reaction.
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Therefore, any DNA strand normally has one end at which there is a phosphate group attached to the 5′ carbon of a ribose (the 5′ phosphoryl) and another end at which there is a free hydroxyl group attached to the 3′ carbon of a ribose (the 3′ hydroxyl). The orientation of the 3′ and 5′ carbons along the sugar-phosphate backbone confers directionality (sometimes called polarity) to each DNA strand. In a nucleic acid double helix, the direction of the nucleotides in one strand is opposite to their direction in the other strand: the strands are antiparallel. The asymmetric ends of DNA strands are said to have a directionality of five prime end (5′ ), and three prime end (3′), with the 5′ end having a terminal phosphate group and the 3′ end a terminal hydroxyl group.
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Blue boxes are enzymes important in transitioning to a cancer metabolic phenotype; orange boxes are enzymes that are mutated in cancer cells. Green ovals are oncogenes that are up-regulated in cancer; red ovals are tumor suppressors that are down-regulated in cancer. The study of the tumor metabolism, also known as tumor metabolome describes the different characteristic metabolic changes in tumor cells. The characteristic attributes of the tumor metabolome are high glycolytic enzyme activities, the expression of the pyruvate kinase isoenzyme type M2, increased channeling of glucose carbons into synthetic processes, such as nucleic acid, amino acid and phospholipid synthesis, a high rate of pyrimidine and purine de novo synthesis, a low ratio of Adenosine triphosphate and Guanosine triphosphate to Cytidine triphosphate and Uridine triphosphate, low Adenosine monophosphate levels, high glutaminolytic capacities, release of immunosuppressive substances and dependency on methionine.
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The protein encoded by the FADS1 gene is a member of the fatty acid desaturase (FADS) gene family and desaturates omega-3 and omega-6 polyunsaturated fatty acids at the delta-5 position, catalyzing the final step in the formation of eicosapentaenoic acid (EPA) and Arachidonic acid. Desaturase enzymes (such as those encoded by FADS1) regulate unsaturation of fatty acids through the introduction of double bonds between defined carbons of the fatty acyl chain. FADS family members are considered fusion products composed of an N-terminal cytochrome b5-like domain and a C-terminal multiple membrane-spanning desaturase portion, both of which are characterized by conserved histidine motifs. This gene is clustered with family members FADS1 and FADS2 at 11q12-q13.1; this cluster is thought to have arisen evolutionarily from gene duplication based on its similar exon/intron organization.
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As desalinization and purification of water is critical for obtaining deionized water for laboratory research, large-scale chemical synthesis in industry and consumer applications, the use of porous materials for this application has received particular interest. Capacitive deionization operates in a fashion with similarities to a supercapacitor. As an ion-containing water (electrolyte) is flown between two porous electrodes with an applied potential across the system, the corresponding ions assemble into a double layer in the pores of the two terminals, decreasing the ion content in the liquid exiting the purification device. Due to the ability of carbide-derived carbons to closely match the size of ions in the electrolyte, side-by-side comparisons of desalinization devices based on CDCs and activated carbon showed a significant efficiency increase in the 1.2–1.4 V range compared to activated carbon.
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Protest and widespread opposition to exporting gas through Chile led to the resignation of President Sanchez de Lozada in October 2003. The government held a binding referendum in 2004 on plans to export natural gas and on hydrocarbons law reform. By May 2005, the carbons law draft was being considered by the Senate. According to the data of the International Monetary Fund, the World Bank, as well as several international Institutes such as ECLAC, during the period 2006 to 2019 (period of the presidency of Evo Morales and Alvaro Garcia Linera) the economy of Bolivia quadrupled from a value of 9,573 million dollars to 42,401 million dollars, this is due in large part to the policy of nationalization of Natural Resources, the stability of the exchange rate, the incentive of the domestic market, strong public investment in infrastructure and industrialization of natural resources such as gas and lithium.
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Another member of this family, CYP4F3, is approximately 18 kb away. In addition to seminal vesicles, CYP4F8 is expressed in kidney, prostate, epidermis, and corneal epithelium, and its mRNA has been found in retina; CYP4F8 is also greatly up-regulated in psoriatic skin. In addition to its ability to metabolize and presumably thereby to inactivate or reduce the activity of PGH2 and PGH1, CYP4F8 adds hydroxyl residues to carbons 18 and 19 of arachidonic acid and Dihomo-γ-linolenic acid, CYP458 possesses epoxygenase activity in that it metabolizes the omega-3 fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid, (EPA) to their corresponding epoxides, the epoxydocosapentaenoic acids (EDPs) and epoxyeicosatetraenoic acids (EEQs), respectively. The enzyme metabolizes DHA primarily to 19R,20S-epoxyeicosapentaenoic acid and 19S,20R-epoxyeicosapentaenoic acid isomers (termed 19,20-EDP) and EPA primarily to 17R,18S-eicosatetraenic acid and 17S,18R-eicosatetraenic acid isomers (termed 17,18-EEQ).
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Weeks later the United States Electric Lighting Company was organized. This company didn't make their first commercial installation of incandescent lamps until the fall of 1880 at the Mercantile Safe Deposit Company in New York City, about six months after the Edison incandescent lamps had been installed on the Columbia. Hiram S. Maxim was the chief engineer at the United States Electric Lighting Company.The National Cyclopedia of American Biography, Vol VI 1896, p. 34 Lewis Latimer, employed at the time by Edison, developed an improved method of heat-treating carbon filaments which reduced breakage and allowed them to be molded into novel shapes, such as the characteristic "M" shape of Maxim filaments. On 17 January 1882, Latimer received a patent for the "Process of Manufacturing Carbons", an improved method for the production of light bulb filaments, which was purchased by the United States Electric Light Company.
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Discounting rotations of the whole molecule, that configuration is a single isomer — the so-called staggered conformation. Rotation between the two halves of the molecule 1,2-dichloroethane (– also has three local energy minima, but they have different energies due to differences between the H–H, Cl–Cl, and H–Cl interactions. There are therefore three rotamers: a trans isomer where the two chlorines are on the same plane as the two carbons, but with oppositely directed bonds; and two gauche isomers, mirror images of each other, where the two – groups are rotated about 109° from that position. The computed energy difference between trans and gauche is ~1.5 kcal/mol, the barrier for the ~109° rotation from trans to gauche is ~5 kcal/mol, and that of the ~142° rotation from one gauche to its enantiomer is ~8 kcal/mol.Kenneth B. Wiberg and Mark A. Murcko (1987): "Rotational barriers. 1. 1,2-Dihaloethanes".
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In the diamond-like structure, called cubic boron nitride (tradename Borazon), boron atoms exist in the tetrahedral structure of carbons atoms in diamond, but one in every four B-N bonds can be viewed as a coordinate covalent bond, wherein two electrons are donated by the nitrogen atom which acts as the Lewis base to a bond to the Lewis acidic boron(III) centre. Cubic boron nitride, among other applications, is used as an abrasive, as it has a hardness comparable with diamond (the two substances are able to produce scratches on each other). In the BN compound analogue of graphite, hexagonal boron nitride (h-BN), the positively charged boron and negatively charged nitrogen atoms in each plane lie adjacent to the oppositely charged atom in the next plane. Consequently, graphite and h-BN have very different properties, although both are lubricants, as these planes slip past each other easily.
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The membrane metabolites of polyunsaturated fatty acids (PUFAs) have an essential role in intercellular biochemical communications. Crawford (2010) in his chapter Long-chain polyunsaturated fatty acids in human brain evolution reported, with regard to the language of lipids, that the importance of the increased complexity of these lipids was brought about by aerobic metabolism, whereby the simple language of prokaryotes, with only a few words, was developed into a vocabulary of over 1,000 words of eukaryote cells. About 500 million years ago, some nervous cells and some gut cells of vertebrates migrated and specialized in a more complex nervous system: the brain, and in uptake and storage of iodocompounds: the follicular thyroid. In the PUFAs, the presence of a double bond between two carbons (or carbon-carbon double bond) provides them with the possibility of changing their molecular structure through enzymes such as phospholipases, cyclooxygenases and lipoxygenases, etc.
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In the general chemical nomenclature developed by the International Union of Pure and Applied Chemistry (IUPAC), the recommended name of a fatty acid, derived from the name of the corresponding hydrocarbon, completely describes its structure, by specifying the number of carbons and the number and position of the double bonds. Thus, for example, oleic acid would be called "(9Z)-octadec-9-enoic acid", meaning that it has a 18 carbon chain ("octadec") with a carboxyl at one end ("oic") and a double bound at carbon 9 counting from the carboxyl ("9-en"), and that the configuration of the single bonds adjacent to that double bond is cis ("(9Z)") The IUPAC nomenclature can also handle branched chains and derivatives where hydrogen atoms are replaced by other chemical groups. A triglyceride would then be named according to general ester rules as, for example, "propane-1,2,3-tryl 1,2-bis((9Z)-octadec-9-enoate) 3-(hexadecanoate)".
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In enzymology, a 6-pyruvoyltetrahydropterin synthase (PTPS) () is an enzyme that catalyzes the following chemical reaction: 7,8-Dihydroneopterin triphosphate \rightleftharpoons 6-pyruvoyltetrahydropterin + triphosphate frameless This reaction is the second step (shown above) in the biosynthesis of tetrahydrobiopterin from GTP, which is used as a cofactor in the synthesis of aromatic amino acid monooxygenases and nitric oxide synthase PTPS converts 7,8-dihydroneopterin triphosphate to 6-pyruvoyltetrahydropterin (PTP) through the loss of the triphosphate group, a stereospecific reduction of the double bond between the top right nitrogen and carbon in the ring on the triphosphate on the right, the oxidation of the hydroxyl groups located on the first and second carbons of the side chain, and an internal base-catalyzed hydrogen transfer. ] 6-pyruvoyltetrahydropterin synthase (PTPS) can be found in the cytoplasm as well as the nucleus of cells according to immunohistochemical studies conducted. It has also been found that in higher species 6-pyruvoyltetrahydropterin synthase (PTPS) can undergo post-translational modification. This enzyme participates in tetrahydrobiopterin biosynthesis.
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I2 \- Prostacyclin (an example of a prostaglandin, an eicosanoid fatty acid) LTB4 (an example of a leukotriene, an eicosanoid fatty acid) Fatty acids, or fatty acid residues when they are part of a lipid, are a diverse group of molecules synthesized by chain- elongation of an acetyl-CoA primer with malonyl-CoA or methylmalonyl-CoA groups in a process called fatty acid synthesis. They are made of a hydrocarbon chain that terminates with a carboxylic acid group; this arrangement confers the molecule with a polar, hydrophilic end, and a nonpolar, hydrophobic end that is insoluble in water. The fatty acid structure is one of the most fundamental categories of biological lipids and is commonly used as a building-block of more structurally complex lipids. The carbon chain, typically between four and 24 carbons long, may be saturated or unsaturated, and may be attached to functional groups containing oxygen, halogens, nitrogen, and sulfur.
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The atoms A1 and A2, which correspond to the same atom A on the cylinder, must be in the same class. It follows that the circumference of the tube and the angle of the strip are not arbitrary, because they are constrained to the lengths and directions of the lines that connect pairs of graphene atoms in the same class. The basis vectors u and v of the relevant sub-lattice, the (n,m) pairs that define non-isomorphic carbon nanotube structures (red dots), and the pairs that define the enantiomers of the chiral ones (blue dots). Let u and v be two linearly independent vectors that connect the graphene atom A1 to two of its nearest atoms with the same bond directions. That is, if one numbers consecutive carbons around a graphene cell with C1 to C6, then u can be the vector from C1 to C3, and v be the vector from C1 to C5.
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Gas pycnometers are used extensively for characterizing a wide variety of solids such as heterogeneous catalysts, carbons, DIN 51913 Testing of carbon materials – Determination of density by gas pycnometer (volumetric) using helium as the measuring gas metal powders,ASTM B923-02(2008)Standard Test Method for Metal Powder Skeletal Density by Helium or Nitrogen PycnometryMPIF Standard 63: Method for Determination of MIM Components (Gas Pycnometer) soils,ASTM D5550 -06 Standard Test Method for Specific Gravity of Soil Solids by Gas Pycnometer ceramics,ASTM C604 Standard Test Method for True Specific Gravity of Refractory Materials by Gas-Comparison Pycnometer active pharmaceutical ingredients (API's) and excipients,USP<699> "Density of Solids" petroleum coke,ASTM D2638 – 06 Standard Test Method for Real Density of Calcined Petroleum Coke by Helium Pycnometer cement and other construction materials,C. Hall "Water Transport in Brick, Stone and Concrete", Taylor & Francis, 2002, p. 13 cenospheres/glass microballoons and solid foams.
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CYP4F22, like other CYP4F proteins, is a Cytochrome P450 omega hydroxylase, i.e. an enzyme that metabolizes fatty acids to their omega hydroxyl derivatives (see Omega oxidation). This hydroxylation may: a) produce a biologically important signaling molecule such as occurs in the metabolism of 20-carbon straight chain polyunsaturated fatty acid, arachidonic acid, to 20-Hydroxyeicosatetraenoic acid, b) inactivate a biologically important product such as the metabolism of the arachidonic acid metabolite, 5-oxo- eicosatetraenoic acid, to its ~100-fold less potent product, 5-oxo-20-hydroxy- eicosatetraenoic acid, or c) be the first step in the further metabolism of xenobiotics or natural compounds CYP4F22 serves the latter function. It is a type 1 Integral membrane protein located in the endoplasmic reticulum of cells in the stratum granulosum of mammalian, including human, skin where it functions to attach an omega hydroxyl residue to fatty acids that are exceptionally long, 28 or more carbons, i.e.
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Peralta-Yahya 2010 Nat. Commun. 2:483 Because isoprenoids add a methyl side chain every four carbons in the backbone, fuels made from isoprenoids have very low freeze and cloud points, making them suitable as cold-weather diesels and jet fuels. One of the biggest challenges in scaling up microbial fermentations is the stability of the microbial strain: the engineered microorganism will attempt to mutate or shed the metabolic pathway, in part because intermediates in the metabolic pathway accumulate and are toxic to the cells. To balance pathway flux and reduce the cost of producing a desired biofuel, Keasling’s laboratory developed dynamic regulators to sense the levels of intermediates in the pathway and regulate pathway activity.Zhang 2012 Nat Biotechnol 30:354Dahl 2013 Nat Biotechnol 31:1039Chou 2013 Nat Commun 4:2595 These regulators stabilized the pathway and the cell and improved biofuel yields making it possible to grow the engineered cells in large-scale fermentation tanks for fuel production.
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In the proposed first step in loline biosynthesis, these two amino acids are coupled in a condensation reaction linking the γ-carbon in homoserine to the secondary amine in proline in a PLP–type enzyme–catalyzed reaction to form the loline intermediate, N-(3-amino-3-carboxy)propylproline (NACPP). Further steps in loline biosynthesis are thought to proceed with sequential PLP-enzyme-catalyzed and oxidative decarboxylations of the carboxy groups in the homoserine and proline moieties, respectively, cyclization to form the core loline ring structure, and oxidation of the C-2 and C-7 carbons to give the oxygen bridge spanning the two pyrrolizidine rings. Genetic studies agree with the biosynthetic routes established in the precursor-feeding experiments. AFLP-based studies using crosses between strains of the endophyte, Epichloë festucae, that differ in the capacity to produce lolines, show that loline production and protection of the grass, Lolium giganteum, from feeding by the aphid, Rhopalosiphum padi, segregate in a Mendelian fashion.
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EPA is a straight-chain, 20 carbon omega-3 fatty acid containing cis (see Cis–trans isomerism) double bonds between carbons 5 and 6, 8 and 9, 11 and 12, 14 and 15, and 17 and 18; each of these double bonds is designated with the notation Z to indicate its cis configuration in the IUPAC Chemical nomenclature used here. EPA is therefore 5Z,8Z,11Z,14Z,17Z-eicosapentaenoic acid. Certain cytochrome P450 epoxygenases metabolize EPA by converting one of these double bounds to an epoxide thereby forming one of 5 possible eicosatetraenoic acid epoxide regioisomers (see Structural isomer, section on position isomerism (regioisomerism)). These regioisomers are: 5,6-EEQ (i.e. 5,6-epoxy-8Z,11Z,14Z,17Z-eicosatetraenoic acid), 8,9-EEQ (i.e. 8,9-epoxy-5Z,11Z,14Z,17Z-eicosatetraenoic acid), 11,12-EEQ (i.e. 11,12-epoxy-5Z,8Z,14Z,17Z-eicosatetraenoic acid), 14,15-EEQ (i.e. 14,15-epoxy-5Z,8Z,11Z,17Z-eicosatetraenoic acid, and 17,18-EEQ (i.e.
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Both graphene and fullerene bear resemblance in having sp2 hybridized carbons however, exhibit different geometries (allotropes of carbon). The fact that fullerenes have five membered rings incorporated among six membered rings, makes them spherical whereas graphene remains planar due to the presence of exclusively all six membered rings in it. In general, the ideal C-C bond length and angle for C-C-C or C-C-H is about 1.42 Å and 2π/3 respectively whereas in corannulene structure, a five membered ring is surrounded by six membered rings contributing to non- planarity in the molecule. This leads to change in bond angles and bond lengths rendering non-planarity in the structure. Such type of contortions in the structure of PAHs are known as ‘arching distortions’. The hydrogen and carbon atoms of the PAH molecule which are either closest to one another due to non-planar structure or suffer from angle strain are known as the "saturated" ones and may serve as a source of ‘splitting distortions’ Figure 2.
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In the first stage of the Calvin cycle, a molecule is incorporated into one of two three-carbon molecules (glyceraldehyde 3-phosphate or G3P), where it uses up two molecules of ATP and two molecules of NADPH, which had been produced in the light-dependent stage. The three steps involved are: Calvin cycle step 1 (black circles represent carbon atoms) Calvin cycle steps 2 and 3 combined # The enzyme RuBisCO catalyses the carboxylation of ribulose-1,5-bisphosphate, RuBP, a 5-carbon compound, by carbon dioxide (a total of 6 carbons) in a two- step reaction. The product of the first step is enediol-enzyme complex that can capture or . Thus, enediol-enzyme complex is the real carboxylase/oxygenase. The that is captured by enediol in second step produces an unstable six-carbon compound called 2-carboxy 3-keto 1,5-biphosphoribotol (or 3-keto-2-carboxyarabinitol 1,5-bisphosphate) that immediately splits into 2 molecules of 3-phosphoglycerate, or 3-PGA, a 3-carbon compoundCampbell, and Reece Biology: 8th Edition, page 198.
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CYP4F12 is expressed in the liver and throughout the gastrointestinal track, is known to metabolize the anti-histamine drugs, ebastine and terfenadine, and therefore is suggested to be positioned for and possibly involved in the processing of these and perhaps other drugs. When expressed in yeast the enzyme is capable of oxidizing arachidonic acid by adding a hydroxyl residue to carbons 18 or 19 to form 18-hydroxyeicosatetraenoic acid (18-HETE) or 19-HETE; however, its physiological function in doing so has not been determined. CYP4F12 also metabolizes prostaglandin H2 (PGH2) and PGH1 to their corresponding 19-hydroxyl analogs in a reaction that might serve to reduce their activities. In addition to these monooxygenase actions, CYP458 possesses epoxygenase activity: it metabolizes the omega-3 fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid, (EPA) to their corresponding epoxides, the epoxydocosapentaenoic acids (EDPs) and epoxyeicosatetraenoic acids (EEQs), respectively. The enzyme metabolizes DHA primarily to 19R,20S-epoxyeicosapentaenoic acid and 19S,20R-epoxyeicosapentaenoic acid isomers (termed 19,20-EDP) and EPA primarily to 17R,18S-eicosatetraenic acid and 17S,18R-eicosatetraenic acid isomers (termed 17,18-EEQ).
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The pyramidal core is about 1.18 ångströms high, and each of the methyl groups on the ring is located slightly above that base plane to give a somewhat inverted tetrahedral geometry for the carbons of the base of the pyramid. The preparation method involved treating the epoxide of hexamethyl Dewar benzene with magic acid, which formally abstracts an oxide anion () to form the dication: 500px Though indirect spectroscopic evidence and theoretical calculations previously pointed to their existence, the isolation and structural determination of a species with a hexacoordinate carbon bound only to other carbon atoms is unprecedented, and has attracted comment in Chemical & Engineering News, New Scientist, Science News, and ZME Science. The carbon atom at the top of the pyramid is bonding with six other atoms, an unusual arrangement as the usual maximum valence for this element is four. The molecule is aromatic and avoids exceeding the octet on carbon by having only a total of six electrons in the five bonds between the base of the pyramid and its apex.
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CYP24A1 is an enzyme expressed in the mitochondrion of humans and other species. It catalyzes hydroxylation reactions which lead to the degradation of 1,25-dihydroxyvitamin D3, the physiologically active form of vitamin D. Hydroxylation of the side chain produces calcitroic acid and other metabolites which are excreted in bile. CYP24A1 was identified in the early 1970s and was first thought to be involved in vitamin D metabolism as the renal 25-hydroxyvitamin D3-24-hydroxylase, modifying calcifediol (25-hydroxyvitamin D) to produce 24,25-dihydroxycholecalciferol (24,25-dihydroxyvitamin D). Subsequent studies using recombinant CYP24A1 showed that it could also catalyze multiple other hydroxylation reactions at the side chain carbons known as C-24 and C-23 in both 25-OH-D3 and the active hormonal form, 1,25-(OH)2D3. It is now considered responsible for the entire five-step, 24-oxidation pathway from 1,25-(OH)2D3 producing calcitroic acid. CYP24A1 also is able to catalyse another pathway which starts with 23-hydroxylation of 1,25-(OH)2D3 and culminates in 1,25-(OH)2D3-26,23-lactone.
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The Jeddah Agreement granted Saudi Arabia a corridor eastwards from Khawr al Udayd, thus giving the Saudis an outlet to the Persian Gulf on the eastern side of Qatar. In return, the UAE was to keep six villages in the area of Al-Buraimi, including al-Ain, and most of al-Zafra desert. Al-Ain/Al-Buraimi oasis region consists of nine oases/villages, seven of which - Al Ain, Al Jaheli, Al Qattarah, Al Muwaiji, Al Hill, Al Masudi, and Al Muhtaredh are today under Abu Dhabi’s control, while the remaining three, namely Hamasa, Sa'ara and Buraimi, today belong to the Sultanate of Oman. Article 3 of the agreement stated that "all hydrocarbons in the Shaybah-Zarrara field shall be considered as belonging to the Kingdom of Saudi Arabia" and provided for exploration and development of the whole field by Saudi Arabia. Article 4 stipulated that Saudi Arabia and the UAE “each undertake to refrain from engaging in and from permitting the exploitation of hydro-carbons in that part of its territory to which the hydrocarbon fields primarily located in the territory of the other state extend.
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The free-floating fatty acids, released from adipose tissues to the blood, bind to carrier protein molecule known as serum albumin that carry the fatty acids to the cytoplasm of target cells such as the heart, skeletal muscle, and other tissue cells, where they are used for fuel. But before the target cells can use the fatty acids for ATP production and β oxidation, the fatty acids with chain lengths of 14 or more carbons must be activated and subsequently transported into mitochondrial matrix of the cells in three enzymatic reactions of the carnitine shuttle. The first reaction of the carnitine shuttle is a two-step process catalyzed by a family of isozymes of acyl-CoA synthetase that are found in the outer mitochondrial membrane, where they promote the activation of fatty acids by forming a thioester bond between the fatty acid carboxyl group and the thiol group of coenzyme A to yield a fatty acyl–CoA. In the first step of the reaction, acyl-CoA synthetase catalyzes the transfer of adenosine monophosphate group (AMP) from an ATP molecule onto the fatty acid generating a fatty acyl–adenylate intermediate and a pyrophosphate group (PPi).
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This is a well-known 1,3-dipole in organic chemistry, positioned in the enzyme active site near to the α,β-unsaturated carboxylic acid substrate which contains a 1,3-dipolarophile. Thus, it was proposed that a 1,3-dipolar cycloaddition mechanism was responsible for the enzymatic decarboxylation. This was confirmed in a later paper The mechanism proposed in for 1,3-dipolar cycloaddition by Fdc1 is as follows (intermediates represented in Figure 1): # 1,3-dipolar cycloaddition between prFMNiminium and the α,β-unsaturated substrate leads to a pyrrolidine cycloadduct (Int1) # This pyrrolidine cycloadduct supports simultaneous decarboxylation and ring opening, resulting in the formation of a distinct prFMN-alkene adduct (Int2) # A conserved glutamic acid residue (E282) donates a proton to the alkene moiety, resulting a second pyrrolidine cycloadduct (Int3) # The reaction concludes with cycloelimination of Int3 and the release of the alkene product and CO2 A study went on to present evidence for the 1,3-dipolar cycloaddition, due to suspected turnover of cinnamic acid a crystal structure of AnFdc1 in complex with α-fluorocinnamic acid revealed the substrate Cα and Cβ carbons are located directly above the prFMNiminium C1’ and C4a respectively (shown as Sub in Figure 1 - with cinnamic acid as opposed to α-fluorocinnamic acid).
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71, No. 2, pp. 209–219, 1999 Link Examples include fullerenes, nanotubes, corannulenes, helicenes and sumanene. The molecular orbitals of the carbon atoms in these systems are to some extent pyramidalized resulting a different pi electron density on either side of the molecule with consequences for reactivity. One member of this group of organic compounds, pentaindenocorannulene (depicted below),Pentaindenocorannulene and Tetraindenocorannulene: New Aromatic Hydrocarbon Systems with Curvatures Surpassing That of C60Edward A. Jackson, Brian D. Steinberg, Mihail Bancu, Atsushi Wakamiya, and Lawrence T. Scott J. Am. Chem. Soc.; 2007; 129(3) pp 484 - 485; (Communication) The two steps in this sequence are a Suzuki-Miyaura coupling with an ionic liquid and Tris(dibenzylideneacetone)dipalladium(0) and a Heck reaction with another palladium catalyst, DBU and DMAC can be considered a large fullerene fragment. The experimentally obtained curvature and degree of pyramidalizion (12.6° for the carbons of the pentagon at the center by a so-called p-orbital axis vector (POAV). The value for fullerene is 11.6° and benzene 0°) are both actually larger than that of fullerene but according to its discoverers, the compound is relatively easy to synthesize starting from corannulene and a way is opened to produce larger such fragments by stitching. Synthesis of Pentaindenocorannulene The crystal structure of pentaindenocorannulene has been obtained.
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5-HEDH is an NADPH dehydrogenase oxidoreductase enzyme. It transfers a hydrogen cation or Hydron (chemistry) (H+) from 5(S)-hydroxy (i.e. 5(S-OH) residues of its fatty acid targets to Nicotinamide adenine dinucleotide phosphate (NADP) to form 5-oxo (i.e. 5-O=) counterparts of its targets plus reduced NADP+, i.e. NADPH. The reaction (where R indicates a long chain [14 or more carbons] fatty acid) is: ::::::::::::::;;:::::NADP+ \+ 5(S)-hydroxy fatty acid (i.e. 5(S)-OH-R) \rightleftharpoons NADPH + H+ \+ oxo fatty acid (i.e. 5-O=R) The reaction appears to follow a ping-pong mechanism. It is fully reversible, readily converting 5-oxo targets to their corresponding 5(S)-hydroxy counterparts. The direction of this reaction is dependent on the level of NADP+ relative to that of NADPH: a) cells bearing high NADP+/NADPH ratios convert 5-hydroxy fatty acids which they make or are presented with to 5(S) fatty acids; b) cells bearing low NADP+/NADPH ratios convert little or none of the 5-hydroxy fatty acids which they make or are presented with to 5-oxo fatty acids and rapidly reduce the 5-oxo fatty acids which they are presented with to the corresponding 5(S)-hydroxy fatty acids.
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