"Oxidation is a known factor in male infertility," Reitano says.
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Wrapping meat in vacuum packaging prevents oxidation, extending its lifespan.
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By 1906, oxidation had covered it with a green patina.
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"Factors that cause spoilage are water loss and oxidation," Rogers told TechCrunch.
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"They will counteract oxidation and keep the hair from getting brassy," he says.
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Consciousness is a product of brain metabolism, which is the oxidation of glucose.
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It is particularly more vulnerable to oxidation because of its high iron content.
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N) said on Friday that turbine blade oxidation which forced Exelon Corp (EXC.
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Markers of blood-fat oxidation, which contributes to plaque buildup, rose as well.
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It is also subjected to the slow, controlled oxidation of prolonged barrel aging.
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Repeatedly heating oils for cooking, especially when deep-frying, can cause oxidation of oils.
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Neither company provided details about the oxidation or how it led to the shutdowns.
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The oxidation process is where the magic happens, with each strain adopting distinctive flavours.
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Each page was encased in a clear plastic sleeve, to prevent oxidation and decay.
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Basically, a handwarmer heats up through a chemical reaction that causes oxidation of the iron.
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Antioxidants inhibit oxidation, thus staving off the effects wrought by a buildup of free radicals.
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The carbon stored in dead plant tissues would then escape into the atmosphere through oxidation.
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For example, photochemical oxidation leading to ozone may also increase the toxicity of hydrocarbon particulates.
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It's very important to keep vermouth refrigerated and sealed, as this preserves it from oxidation.
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Yet Ms Aga says that advanced oxidation processes can filter out many drugs and beauty products.
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It's very important to keep vermouth refrigerated and sealed as this preserves it from oxidation. 3.
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It was the atmosphere around the metal was adding weight—a process we now call oxidation.
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So as the oxidation of glucose increases, more and more cells reach that level of consciousness.
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It depicts the Confederacy's top general, larger than life, astride a horse, both green with oxidation.
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The oxygen tank also has an oxidation risk problem as it is pressurized with pure, hot oxygen.
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All of this needs to be done in the presence of oxygen, as fire is an oxidation reaction.
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It's made from Samsung's proprietary magnesium alloy called Metal 12, finished with a microarc oxidation process for durability.
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Light photons strike the photoelectrode directly, knocking lose electrons and holes, which in turn drive oxidation and reduction.
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And confusingly, the signatures demonstrate the oxygen decreasing before the Great Oxidation Event left its mark on ancient sulfur.
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These materials ensure that there is minimal oxidation, so your OJ maintains its natural taste and maximum nutritional value.
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But Perlman mills the beans into flour, in a cold liquid nitrogen environment to prevent oxidation and CGA loss.
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In addition, the quality of that foreign steel is clearly inferior, subject to fast oxidation (rusting) or actual fracture.
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GE told Reuters it identified the oxidation problem in 2015, and developed a fix before the failure in Texas.
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The Statue of Liberty's exterior is made of copper, and it turned that shade of green because of oxidation.
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The Guac-Lock is a bowl that effectively eliminates exposure to air, preventing the oxidation that discolors the avocados.
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Finally, it's possible there is some variable at play that no one has paid adequate attention to — like oxidation.
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Rather than merely trapping indoor air pollutants, the Molekule air purifier uses its proprietary Photo Electrochemical Oxidation to destroy them.
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"A lot of research points to oxidation being the basis for conditions like cancer and heart disease," Kris-Etherton said.
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This is counter to almost every other winemaking procedure, in which the aim is to protect the wine from oxidation.
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This is counter to almost every other winemaking procedure, in which the aim is to protect the wine from oxidation.
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"We had an oxidation issue that created cracking ... we've upgraded about 23 of the 33" turbines in the operation, Culp said.
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This $8 little container's tight-fitting lid and avocado-specific shape help reduce the oxidation that turns avocados that unappealing color.
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This may lead to excess amounts of storage, or insufficient efforts to mitigate oxidation or leaks and thereby save valuable fuel.
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Its rustic hammered appearance and natural rainbow hues due to heat and oxidation enhance and blend into a busy kitchen setting.
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Iron is a key indicator of "oxygen fugacity," which is a measurement of the past oxidation levels of a planetary body.
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"All metallic objects, when they do hair clipping, go through oxidation and rust and can be injurious to skin," he said.
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Another explanation for the methane in Mars's atmosphere could be that it is produced by geological phenomena, like the oxidation of iron.
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"As soon as you chop that kale, you're basically breaking the cell walls, and that begins the oxidation process," Ms. Armstrong said.
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But there is no question that oxidation, so crucial to life, rusts our cells and can edge them closer to becoming cancerous.
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Transfer to a bowl and drizzle with the olive oil, tossing well (be sure to coat the sunchokes well, to prevent oxidation).
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Molekule has a new technology called Photo Electrochemical Oxidation, or PECO, which uses UV-A wavelength LED lights to simulate solar light.
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At some point around 1900, that copper went through an oxidation process that gave the metal its iconic shade of blue-green.
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Things turned ironic with Andy Warhol's Oxidation series, achieved by the artist and others urinating on canvases painted with copper metallic paint.
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Over eons, tectonic forces and erosion have lifted the rock and exposed zigzagging strata, made colorful by differing stages of iron oxidation.
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The plastic packs, which prevent oxidation, mean meat can stay on shelves for between five and eight days, rather than two to four.
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The artwork uses Morozov's blood to generate electricity, using electrolyte liquid and metals (copper and aluminum) with varying oxidation rates as power sources.
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Eat foods rich in antioxidants, chemicals that inhibit the oxidation of molecules by neutralizing free radicals, thereby stopping them from causing cellular damage.
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This, they say, is when blackheads and sebaceous filaments break free and the grits slide right out, black on one end from oxidation.
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Reuters previously reported that GE found an oxidation problem, not a break, in 2000 and developed a fix before the failure in Texas.
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"However, other purely geological processes, such as the oxidation of certain minerals, also release methane," the European Space Agency said on its website.
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Another explanation for the methane in Mars's atmosphere could be that it is produced by geological phenomena, such as the oxidation of iron.
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Oxidation is not good, so if you can help protect the body through the foods that you eat, that could be very beneficial.
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And to fight oxidation, the team added a small sachet of iron filings to the sealed pouch, which will bind any free oxygen.
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"Hopefully, as we move you up in intensity by stage, we're going to see a nice bell curve representing fat oxidation," she says.
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By coating the fruit and vegetables in the substance, the rate of water loss and oxidation — the main causes of spoilage — is reduced.
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It may be used again after fermentation to prevent oxidation and microbiological spoilage in the wine, and again before bottling as a stabilizer.
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It's there because the oxidation pond on her street, which is supposed to clean the neighborhood sewage, is broken and hasn't been fixed.
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The scientists found that decreases in sulfur and iron along with increases in phosphorus paralleled the Great Oxidation Event and the Neoproterozoic Oxygen Event.
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Plant operator KKL AG said in a statement that the tubes needed to be further assessed and swapped, as they pointed to oxidation problems.
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Oxidation is a finely balanced process, which means at high levels, antioxidants could morph into "pro-oxidants" and could create more damage, experts say.
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The heat produced by the spinning breaks down enzymes and speeds up oxidation, lightening the colour and giving it a not-so-fresh taste.
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The heat produced by the spinning breaks down enzymes and speeds up oxidation, lightening the color and giving juice a not-so-fresh taste.
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They told me the oxidation problems would be so bad to his brain, that he would be a vegetable if he even made it.
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Through this unorthodox strategy, he guides the otherwise unpredictable oxidation process as the rust stains the canvases in rhythmic and melancholic figurations and patterns.
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News of the oxidation problem trickled out Wednesday when GE Power Chief Executive Russell Stokes mentioned it in a post on the LinkedIn website.
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In the meantime, she was learning a lot about tea, she said, about the oxidation process, about the proper way to steep different varieties.
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If a dairy case is lit with LEDs, for example, oxidation in milk may occur, which can make milk taste like plastic, she explained.
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Other star ingredients include niacinamide, which controls oil, and vitamin C, which regulates the oxidation of lipids that can be irritating to the skin.
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The heat produced by the spinning breaks down enzymes and speeds up oxidation, lightening the color and giving it a not-so-fresh taste.
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Goodyear hasn't made the all-important compound, and getting it to work as described would be complex, especially the bit about hardening with oxidation.
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"The two leading causes of produce spoilage are water loss and oxidation — that's water evaporating out of the produce and oxygen getting in," Rogers says.
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Among his innovations was the process of cold fermentation of white wines, which prevented oxidation that occurred when the wines were fermented at higher temperatures.
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As for oxidation—a common issue—Marquis pulls out a drawing by 19th century landscape artist Winslow Homer to describe the usual course of action.
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The team's calculations showed that anywhere from 80 to 99.5% of organisms were wiped out at the end of the Great Oxidation Event, Hodgskiss said.
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The company's bioreactors have been specifically designed for the chemicals it makes, but the real innovation is looking at enzymes as a tool for oxidation chemistries.
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He adds the disclaimer that juicing or blending vegetables is likely to strip out some of their vitamins—mostly due to "oxidation" caused by air exposure.
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Disperse leaks of pollution from oil and gas storage and coal oxidation are not directly measured, unlike exhaust passing through smokestack monitors or vehicle tailpipe testing.
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This process creates such a tight seal on the lid that it's almost impossible to open without using the depressurizing cap, which reduces oxidation and bubbles.
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NanoSeptic's technology, which is powered by light, uses mineral nano-crystals to create an oxidation reaction that is stronger than bleach, according to the company's website.
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Yet there they are: cork taint, oxidation, volatile acidity and other problems that can cause the most highly anticipated bottles to be poured down the drain.
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Chaperone proteins that keep the strands in order may fail, and the strands are also subject to chemical processes, including oxidation, that can change their color.
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Forget the antioxidant pills; just stick with veggies Normally, when an electron separates from a molecule involved in oxidation and reduction, it reattaches almost immediately to another.
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All the methods are meant to reduce the amount of air that comes in contact with guac, which leads to oxidation (and then browning) of the dip.
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Such studies reminded researchers that oxidation isn't all bad; it helps kill bacteria and malignant cells, wiping them out before they can grow into tumors, Miller said.
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Preserving a plastic artwork also may mean keeping the temperature low and humidity stable to reduce plasticizer migration, or providing an oxygen-free environment to prevent oxidation.
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"However, you do create damage to plant cells, potentially releasing enzymes and other factors, as well as create more surface area for oxidation to occur," Ferruzzi said.
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Oxidation scanning probe lithography (o-SPL), also called local oxidation nanolithography (LON), scanning probe oxidation, nano-oxidation, local anodic oxidation, AFM oxidation lithography is based on the spatial confinement of an oxidation reaction.
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Diaziridines can be oxidized to diazirines by a number of methods. These include oxidation by chromium based reagents such as the Jones oxidation, oxidation by iodine and triethylamine, oxidation by silver oxide, oxidation by oxalyl chloride, or even electrochemical oxidation on a platinum-titanium anode. Jones oxidation of a generic diaziridine to a diazirine.
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Image 6: E2 Succinate oxidation mechanism. Image 7: E1cb Succinate oxidation mechanism.
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The compound is prepared in the laboratory by oxidation of acenaphthene with potassium dichromate. Commercially, oxidation is effected with peroxide. Over-oxidation gives naphthalenedicarboxylic anhydride.
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Oxidation reaction of cyclohexane to synthesize adiapic acid An oxidation reaction to form adipic acid is shown in figure 3 and it can be catalyzed by cobalt nanoparticles. This is used in an industrial scale to produce the nylon 6,6 polymer. Other examples of oxidation reactions that are catalyzed by metallic nanoparticles include the oxidation of cyclooctane, the oxidation of ethene, and glucose oxidation.
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32, p. 35 (1952). Online article Oxidation of ketones having α-methylene groups affords diketones. This type of oxidation with selenium oxide is called Riley oxidation.
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While other oxidation technologies such as thermal oxidation produces CO, NO2 and CO2.
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An alternative method for the oxidation of primary alcohols to aldehydes is the Swern oxidation.
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Several chromium oxides are used for related oxidations. These include Jones oxidation and Sarett oxidation.
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Solid potassium permanganate decomposes when heated: : 2 KMnO4 → K2MnO4 \+ MnO2(s) + O2 Here, the oxidation state of manganese changes as the potassium permanganate (oxidation state +7) decomposes to potassium manganate (oxidation state +6) and manganese dioxide (oxidation state +4). Oxygen gas is also liberated.
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This was in contrast to the more familiar +3, +4, +5, +6, and +7 oxidation states. Most recently, Evans analyzed the synthesis of the oxidation-reduction reaction of complex (C5Me5)2ThMe2, where thorium was reduced from the +4 oxidation state to the +3 oxidation state.
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The approach will be based on utilizing a novel selective photocatalytic oxidation technology for the selective oxidation of ethylene and ethane to acetic acid. Unlike traditional oxidation catalysts, the selective oxidation process will use UV light to produce acetic acid at ambient temperatures and pressure.
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A reductant transfers electrons to another substance and is thus oxidized itself. And because it "donates" electrons it is also called an electron donor. Oxidation and reduction properly refer to a change in oxidation number—the actual transfer of electrons may never occur. Thus, oxidation is better defined as an increase in oxidation number, and reduction as a decrease in oxidation number.
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Though sufficient for many purposes, these general descriptions are not precisely correct. Although oxidation and reduction properly refer to a change in oxidation state, the actual transfer of electrons may never occur. The oxidation state of an atom is the fictitious charge that an atom would have if all bonds between atoms of different elements were 100% ionic. Thus, oxidation is best defined as an increase in oxidation state, and reduction as a decrease in oxidation state.
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Reagents useful for the oxidation of secondary alcohols to ketones, but normally inefficient for oxidation of primary alcohols to aldehydes, include chromium trioxide (CrO3) in a mixture of sulfuric acid and acetone (Jones oxidation) and certain ketones, such as cyclohexanone, in the presence of aluminium isopropoxide (Oppenauer oxidation). Another method is oxoammonium-catalyzed oxidation. Additionally, sodium hypochlorite (or household bleach) in acetone has been reported for efficient conversion of secondary alcohols in the presence of primary alcohols (Stevens oxidation).
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Local oxidation procedure: 3D representation the Local Oxidation Nanolithography process. A voltage pulse applied between the AFM tip and the scanned surface yields to the formation of a liquid meniscus that confines a nanometric oxidation reaction. Local oxidation nanolithography (LON) is a tip- based nanofabrication method. It is based on the spatial confinement on an oxidation reaction under the sharp tip of an atomic force microscope.
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Metal chlorates can be prepared by adding chlorine to hot metal hydroxides like KOH: :3 Cl2 \+ 6 KOH → 5 KCl + KClO3 \+ 3 H2O In this reaction, chlorine undergoes disproportionation, both reduction and oxidation. Chlorine, oxidation number 0, forms chloride Cl− (oxidation number −1) and chlorate(V) (oxidation number +5). The reaction of cold aqueous metal hydroxides with chlorine produces the chloride and hypochlorite (oxidation number +1) instead.
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It is predicted that even a +10 oxidation state may be achievable by platinum in the tetroxoplatinum(X) cation (). The lowest oxidation state is −5, as for boron in Al3BC. The increase in oxidation state of an atom, through a chemical reaction, is known as an oxidation; a decrease in oxidation state is known as a reduction. Such reactions involve the formal transfer of electrons: a net gain in electrons being a reduction, and a net loss of electrons being an oxidation.
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As nanowire oxidation rate is controlled by diameter, thermal oxidation steps are often applied to tune their morphology.
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The column for oxidation state 0 only shows elements known to exist in oxidation state 0 in compounds.
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There are three sets of gallium halides, the trihalides where gallium has oxidation state +3, the intermediate halides containing gallium in oxidation states +1, +2 and +3 and some unstable monohalides, where gallium has oxidation state +1.
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In electrochemistry, the anode is where oxidation occurs and is the positive polarity contact in an electrolytic cell. At the anode, anions (negative ions) are forced by the electrical potential to react chemically and give off electrons (oxidation) which then flow up and into the driving circuit. Mnemonics: LEO Red Cat (Loss of Electrons is Oxidation, Reduction occurs at the Cathode), or AnOx Red Cat (Anode Oxidation, Reduction Cathode), or OIL RIG (Oxidation is Loss, Reduction is Gain of electrons), or Roman Catholic and Orthodox (Reduction – Cathode, anode – Oxidation), or LEO the lion says GER (Losing electrons is Oxidation, Gaining electrons is Reduction). This process is widely used in metals refining.
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Oxidation routes of HMF into FDCAThe second class of synthesis routes include the oxidation reactions of various 2,5-disubstituted furans utilizing a variety of inorganic oxidants. Several routes to FDCA via oxidation of hydroxymethylfurfural (HMF) with air over different catalysts have been reported. Oxidation of HMF under strongly alkaline conditions over noble metal catalysts gives almost quantitative formation of FDCA. HMF and methoxymethylfurfural (MMF) oxidation was also studied with a series of conventional metal bromide catalysts (Co, Mn, Br) used for the oxidation of para-xylene to terephthalic acid.
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There are a number of variants and alternatives of the Kornblum oxidation. These alterations include using silver-assisted DMSO oxidations, the use of amine oxides as oxidants (occasionally called the Ganem oxidation), the use of pyridine-N-oxide or 2-picoline-N-oxide and a base, the use of metal nitrates, Sommelet oxidation, and Kröhnke oxidation. The Kornblum oxidation can also be effected through the use of microwave assistance. Microwave assisted organic synthesis of the Kornblum oxidation has been shown to increase yield and decrease the reaction time through elimination of an unnecessary intermediate.
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A characteristic of transition metals is that they exhibit two or more oxidation states, usually differing by one. For example, compounds of vanadium are known in all oxidation states between −1, such as , and +5, such as . Oxidation states of the transition metals. The solid dots show common oxidation states, and the hollow dots show possible but unlikely states. Main group elements in groups 13 to 18 also exhibit multiple oxidation states.
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In organic synthesis, DMSO is used as a mild oxidant, as illustrated by the Pfitzner–Moffatt oxidation and the Swern oxidation.
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Thermal oxidation may be applied to different materials, but most commonly involves the oxidation of silicon substrates to produce silicon dioxide.
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Using the Deal–Grove model it is possible to predict the oxidation kinetics of nanowires fabricated through such thermal oxidation processing.
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In compounds such as and , the elements achieve a stable configuration by covalent bonding. The lowest oxidation states are exhibited in metal carbonyl complexes such as (oxidation state zero) and (oxidation state −2) in which the 18-electron rule is obeyed. These complexes are also covalent. Ionic compounds are mostly formed with oxidation states +2 and +3.
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"Editura Academiei Republicii Socialiste România" Use of the original Sarett oxidation has become largely antiquated however, in favor of other modified oxidation techniques. The unadulterated reaction is still occasionally used in teaching settings and in small scale laboratory research. Schematic showing the oxidation of generic primary, and secondary alcohols into the respective aldehydes and ketones via the Sarett oxidation.
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Hydrogen peroxide is frequently used as an oxidizing agent. Illustrative is oxidation of thioethers to sulfoxides: :Ph + → Ph + Alkaline hydrogen peroxide is used for epoxidation of electron-deficient alkenes such as acrylic acid derivatives, and for the oxidation of alkylboranes to alcohols, the second step of hydroboration-oxidation. It is also the principal reagent in the Dakin oxidation process.
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Antimony compounds are often classified according to their oxidation state: Sb(III) and Sb(V). The +5 oxidation state is more stable.
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Wet oxidation is preferred to dry oxidation for growing thick oxides, because of the higher growth rate. However, fast oxidation leaves more dangling bonds at the silicon interface, which produce quantum states for electrons and allow current to leak along the interface. (This is called a "dirty" interface.) Wet oxidation also yields a lower-density oxide, with lower dielectric strength. The long time required to grow a thick oxide in dry oxidation makes this process impractical.
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The oxidation of primary alcohols to carboxylic acids is an important oxidation reaction in organic chemistry. When a primary alcohol is converted to a carboxylic acid, the terminal carbon atom increases its oxidation state by four. Oxidants able to perform this operation in complex organic molecules, featuring other oxidation-sensitive functional groups, must possess substantial selectivity. The most common oxidants are potassium permanganate (KMnO4), Jones reagent, PCC in DMF, Heyns oxidation, ruthenium tetroxide (RuO4) and TEMPO.
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Diphenylphosphine readily oxidizes. :Ph2PH + O2 → Ph2P(O)OH An intermediate in this oxidation is diphenylphosphine oxide. The use of the diphenylphosphine–borane complex, Ph2PH•BH3 avoids the problem of phosphine oxidation by protecting the phosphine from oxidation and is available through chemical vendors.
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The Corey-Kim oxidation is an oxidation reaction used to synthesise aldehydes and ketones from primary and secondary alcohols. It is named for American chemist and Nobel Laureate Elias James Corey and Korean-American chemist Choung Un Kim. The Corey-Kim oxidation Although the Corey-Kim oxidation possesses the distinctive advantage over Swern oxidation of allowing an operation above –25 °C, it is not so commonly used due to issues with selectivity in substrates susceptible to chlorination by N-chlorosuccinimide.
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The Sarett oxidation efficiently oxidizes primary alcohols to aldehydes without further oxidizing them to carboxylic acids. This key difference from the Jones oxidation is due to the fact that the Jones oxidation occurs in the presence of water, which adds to the alcohol following oxidation to an aldehyde. The Sarett and Collins oxidations occur in the absence of water. The Sarett oxidation also proceeds under basic conditions, which allows for the use of acid sensitive substrates, such as those containing certain protecting groups.
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However, the terminology using "ligands" gave the impression that oxidation number might be something specific to coordination complexes. This situation and the lack of a real single definition generated numerous debates about the meaning of oxidation state, suggestions about methods to obtain it and definitions of it. To resolve the issue, an IUPAC project (2008-040-1-200) was started in 2008 on the "Comprehensive Definition of Oxidation State", and was concluded by two reports and by the revised entries "Oxidation State" and "Oxidation Number" in the IUPAC Gold Book. The outcomes were a single definition of oxidation state and two algorithms to calculate it in molecular and extended-solid compounds, guided by Allen electronegativities that are independent of oxidation state.
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ANAMMOX is anaerobic ammonium oxidation, DNRA is dissimilatory nitrate reduction to ammonium, and COMMAMOX is complete ammonium oxidation. In nitrification, ammonium is converted to nitrite. Important species include Nitrosomonas. Other bacterial species such as Nitrobacter, are responsible for the oxidation of the nitrite into nitrate.
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Photo-oxidation, i.e., photochemical oxidation. A colorant molecule, when excited by a photon of sufficient energy, undergoes an oxidation process. In the process the chromophoric system of the colorant molecule reacts with the atmospheric oxygen to form a non-chromophoric system, resulting in fading.
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The industrial synthesis involves aerobic oxidation of naphthalene over a vanadium oxide catalyst: :CH + 3/2 O → CHO + HO In the laboratory, naphthoquinone can be produced by the oxidation of a variety of naphthalene compounds. An inexpensive route involves oxidation of naphthalene with chromium trioxide.
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Stable and monomeric gallium, indium and thallium radicals with a formal oxidation state of +2 have since been reported. Nihonium may have +5 oxidation state.
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The Pfitzner–Moffatt oxidation, sometimes referred to as simply the Moffatt oxidation, is a chemical reaction for the oxidation of primary and secondary alcohols to aldehydes and ketones, respectively. The oxidant is a combination of dimethyl sulfoxide (DMSO) and dicyclohexylcarbodiimide (DCC). The reaction was first reported by J. Moffatt and his student K. Pfitzner in 1963.J. G. Moffatt, “Sulfoxide-Carbodiimide and Related Oxidations” in Oxidation vol.
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The term "redox" stands for reduction-oxidation. It refers to electrochemical processes involving electron transfer to or from a molecule or ion changing its oxidation state. This reaction can occur through the application of an external voltage or through the release of chemical energy. Oxidation and reduction describe the change of oxidation state that takes place in the atoms, ions or molecules involved in an electrochemical reaction.
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A hill is formed when the left slope is steeper than the right, and a valley is formed when the right slope is steeper than the left. An oxidation number that is on “top of the hill” tends to favor disproportionation into the adjacent oxidation states. The adjacent oxidation states, however, will favor comproportionation if the middle oxidation state is in the “bottom of a valley”.
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To determine the effect of SiC content on diboride oxidation, ManLabs conducted a series of furnace oxidation experiments, in which the oxidation scale thickness as a function of temperature for pure HfB2, SiC and HfB2 20v% SiC were compared. At temperatures greater than 2100 K the oxide scale thickness on pure HfB2 is thinner than that on pure SiC, and HfB2/20% SiC has the best oxidation resistance. Extreme heat treatment leads to greater oxidation resistance as well as improved mechanical properties such as fracture resistance.
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Formally, oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. An atom or ion that gives up an electron to another atom or ion has its oxidation state increase, and the recipient of the negatively charged electron has its oxidation state decrease. For example, when atomic sodium reacts with atomic chlorine, sodium donates one electron and attains an oxidation state of +1. Chlorine accepts the electron and its oxidation state is reduced to −1.
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Energy generation via methane oxidation yields the next best source of energy after sulfur oxidation. It has been suggested that microbial oxidation facilitates rapid turnover at hydrothermal vents, thus much of the methane is oxidize within short distance of the vent. In hydrothermal vent communities, aerobic oxidation of methane is commonly found in endosymbiotic microbes of vent animals. Anaerobic oxidation of methane (AOM) is typically coupled to reduction of sulfate or Fe and Mn as terminal electron acceptors as these are most plentiful at hydrothermal vents.
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The oxidation state, sometimes referred to as oxidation number, describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. Conceptually, the oxidation state, which may be positive, negative or zero, is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic, with no covalent component. This is never exactly true for real bonds. The term oxidation was first used by Antoine Lavoisier to signify reaction of a substance with oxygen.
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There are two motifs to indicate a metal oxidation state based around the actual charge separation of the metal center. Oxidation states up to +3 are believed to be an accurate representation of the charge separation experienced by the metal center. For oxidation states of +4 and larger, the oxidation state becomes more of a formalism with much of the positive charge distributed between the ligands. This distinction can be expressed by using a Roman numeral for the lower oxidation states in the upper right of the metal atomic symbol and an Arabic number with a plus sign for the higher oxidation states (see the example below).
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By obtaining measurements at different temperatures, an accelerated oxidation progression correlation can be established. The prediction of oxidation during service life can then be carried out.
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Cyclohexanone can be prepared from cyclohexanol by oxidation with chromium trioxide (Jones oxidation). An alternative method utilizes the safer and more readily available oxidant sodium hypochlorite.
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In addition to uracil, SMUG1 removes several pyrimidine oxidation products. and has a specific function to remove the thymine oxidation product 5-hydroxymethyl uracil from DNA.
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The oxidised beer presents the mouldy taste of old newspapers. Beer with 100% oxygen exposure has the fastest oxidation rate. Temperature is another cause of oxidation, which produces a lot of oxygen in a high-temperature environment. This oxygen also accelerates the price of beer oxidation.
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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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The Elbs persulfate oxidation is the organic reaction of phenols with alkaline potassium persulfate to form para-diphenols. The Elbs persulfate oxidation Several reviews have been published.
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Transition metal ions, due to their multiple oxidation states, were the only elements capable of controlling the oxidation states of such molecules, and thus were selected for.
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Since SiC–SiC composites are generally sought for in high temperature applications, their oxidation resistance is of high importance. The oxidation mechanism for SiC–SiC composites vary depending on the temperature range, with operation in the higher temperature range (>1000 °C) being more beneficial than at lower temperatures (<1000 °C). In the former case, passive oxidation generates a protective oxide layer wheres in the latter case, oxidation degrades the fiber-matrix interface. Nonetheless, oxidation is an issue and environmental barrier coatings are being investigated to address this issue.
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This so-called "preg-robbing" carbon is washed away because it is significantly finer than the carbon recovery screens typically used to recover activated carbon. Pre-treatment options for refractory ores include: # Roasting # Bio-oxidation, such as Bacterial oxidation # Pressure oxidation # Albion process The refractory ore treatment processes may be preceded by concentration (usually sulfide flotation). Roasting is used to oxidize both the sulfur and organic carbon at high temperatures using air and/or oxygen. Bio-oxidation involves the use of bacteria that promote oxidation reactions in an aqueous environment.
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Mössbauer spectroscopy has also been used to determine the relative concentration change in the oxidation state of antimony (Sb) during the selective oxidation of olefins. During calcination all the Sb ions in an antimony-containing tin dioxide catalyst transform into the +5 oxidation state. Following the catalytic reaction, almost all Sb ions revert from the +5 to the +3 oxidation state. A significant change in the chemical environment surrounding the antimony nucleus occurs during the oxidation state change which can easily be monitored as an isomer shift in the Mössbauer spectrum.
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The term "oxidation state" in English chemical literature was popularized by Wendell Mitchell Latimer in his 1938 book about electrochemical potentials. He used it for the value (synonymous with the German term Wertigkeit) previously termed "valence", "polar valence" or "polar number" in English, or "oxidation stage" or indeed the "state of oxidation". Since 1938, the term "oxidation state" has been connected with electrochemical potentials and electrons exchanged in redox couples participating in redox reactions. By 1948, IUPAC used the 1940 nomenclature rules with the term "oxidation state", instead of the original valency.
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In combination with dimethyl sulfoxide (DMSO), DCC effects the Pfitzner-Moffatt oxidation. This procedure is used for the oxidation of alcohols to aldehydes and ketones. Unlike metal-mediated oxidations, such as the Jones oxidation, the reaction conditions are sufficiently mild to avoid over-oxidation of aldehydes to carboxylic acids. Generally, three equivalents of DCC and 0.5 equivalent of proton source in DMSO are allowed to react overnight at room temperature.
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When a diol or more than one equivalent of alcohol is used, acetoxydialkoxyperiodinane is formed instead. Due to the labile nature of this particular periodinane, oxidation occurs much faster. :Oxidation by Dess-Martin-Periodinan Schreiber and coworkers have shown that water increases the rate of the oxidation reaction. Dess and Martin had originally observed that the oxidation of ethanol was increased when there was an extra equivalent of ethanol.
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One of the key uses for the material is as a free radical initiator for acrylate and methacrylate monomers, and polyester resins. Cumene hydroperoxide is involved as an organic peroxide in the manufacturing of propylene oxide by the oxidation of propylene. This technology was commercialized by Sumitomo Chemical. Oxidation of cumene affords cumene hydroperoxide : + oxidation → The oxidation by cumene hydroperoxide of propylene affords propylene oxide and the byproduct cumyl alcohol.
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Aldehydes, ketones and carboxylic acids along or at the end of polymer chains are generated by oxygenated species in photolysis of photo-oxidation. The initiation of photo-oxidation reactions is due to the existence of chromophoric groups in the macromolecules. Photo- oxidation can occur simultaneously with thermal degradation and each of these effects can accelerate the other. The photo-oxidation reactions include chain scission, cross linking and secondary oxidative reactions.
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The oxidation state of the element is shown on the x axis of the Frost diagram. Oxidation states are unitless and are also scaled in positive and negative integers. Most often, the Frost diagram displays oxidation number in increasing order, but in some cases it is displayed in decreasing order. The neutral, pure element with a free energy of zero (nE° = 0) also has an oxidation state equal to zero.
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In regards to electrochemical reactions, two main types of reactions can be visualized using the Frost diagram. Comproportionation is when two equivalents of an element, differing in oxidation number, combine to form a product with an intermediate oxidation number. Disproportionation is the opposite reaction, in which two equivalents of an element, identical in oxidation number, react to form two products of differing oxidation numbers. Disproportionation: 2 Mn+ → Mm+ \+ Mp+.
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Comproportionation: Mm+ \+ Mp+ → 2 Mn+. 2 n = m + p in both examples. Using a Frost diagram, one can predict whether one oxidation number would undergo disproportionation or two oxidation numbers would undergo comproportionation. Looking at two slopes among a set of three oxidation numbers on the diagram, assuming the two standard potentials (slopes) are not equal, the middle oxidation will either be in a “hill” or “valley” form.
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Sulfoxides are typically prepared by oxidation of sulfides, using oxidants such as hydrogen peroxide. Oxidation of thioanisole can be effected with periodate. In these oxidations, care is required to avoid over oxidation to form a sulfone. Dimethyl sulfide is oxidized to dimethyl sulfoxide and then further to dimethyl sulfone.
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The Stahl oxidation is a component of the undergraduate organic chemistry laboratory curriculum at UW-Madison. In 2013, the mechanism for the copper(I)/TEMPO oxidation of alcohols was elucidated, and it was found the use of less hindered nitroxyl radical sources allowed for the oxidation of secondary alcohols.
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Rhododendrol is metabolised via tyrosinase-catalysed oxidation. Therefore, the enzyme tyrosinase is necessary for the oxidation of rhododendrol. Tyrosinase regularly plays an essential role in the production of melanocytes called the melanogenesis. After oxidation of rhododendrol by the tyrosinase enzyme, several kinds of phenols and catechols are formed.
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As an alternative to di-, tri- prefixes either charge or oxidation state can be used. Charge is recommended as oxidation state may be ambiguous and open to debate.
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Spent caustics are malodorous wastewaters that are difficult to treat in conventional wastewater processes. Typically the material is disposed of by high dilution with biotreatment, deep well injection, incineration, wet air oxidation, Humid Peroxide Oxidation or other speciality processes. Most ethylene spent caustics are disposed of through wet air oxidation.
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Common oxidation states of cobalt include +2 and +3, although compounds with oxidation states ranging from −3 to +5 are also known. A common oxidation state for simple compounds is +2 (cobalt(II)). These salts form the pink-colored metal aquo complex in water. Addition of chloride gives the intensely blue .
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From this structure the liquid acetylene was formed. Next, the crystalline tetrahydrobenz[c]phenanthridine was formed. hydroboration and oxidation produced an alcohol. Jones oxidation gave rise to the ketone.
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Chemical treatments are techniques adopted to make industrial water suitable for use or discharge. These include chemical precipitation, chemical disinfection, chemical oxidation, advanced oxidation, ion exchange, and chemical neutralization.
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The oxidation has an important effect on the taste of the end product, but the amount of oxidation is not an indication of quality. Tea producers match oxidation levels to the teas they produce to give the desired end characteristics. # Then the leaves are dried to arrest the oxidation process. # Finally, the leaves are sorted into grades according to their sizes (whole leaf, brokens, fannings and dust), usually with the use of sieves.
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The sulfur atom in the side-chain of the amino acid cysteine can exist in several different oxidation states. The most reduced of these is as a thiol group (Cys-SH). Oxidation of cysteine produces cystine, which is one half of a disulfide bond (Cys-S-S-Cys). These lower oxidation states of cysteine (disulfides) are readily reversible, but higher oxidation states, such as sulfinic acid (Cys-SOOH), were once considered irreversible, biologically speaking.
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No compounds of zinc in oxidation states other than +1 or +2 are known. Calculations indicate that a zinc compound with the oxidation state of +4 is unlikely to exist.
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The tea producer may choose when the oxidation should be stopped, which depends on the desired qualities in the final tea as well as the weather conditions (heat and humidity). For light oolong teas this may be anywhere from 5–40% oxidation, in darker oolong teas 60–70%, and in black teas 100% oxidation. Oxidation is highly important in the formation of many taste and aroma compounds, which give tea its liquor colour, strength, and briskness. Depending on the type of tea desired, under or over-oxidation can result in grassy flavours, or overly thick winey flavours.
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After activation by ATP, once inside the mitochondria, the β-oxidation of a fatty acids occurs via four recurring steps: #Oxidation by FAD #Hydration #Oxidation by NAD+ # Thiolysis # Production of acyl-CoA and acetyl-CoA The final product of β-oxidation of an even-numbered fatty acid is acetyl-CoA, the entry molecule for the citric acid cycle. If the fatty acid is an odd-numbered chain, the final product of β-oxidation will be propionyl-CoA. This propionyl- CoA will be converted into intermediate methylmalonyl-CoA and eventually succinyl-CoA, which also enters the TCA cycle.
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In 1948 Linus Pauling proposed that oxidation number could be determined by extrapolating bonds to being completely ionic in the direction of electronegativity. A full acceptance of this suggestion was complicated by the fact that the Pauling electronegativities as such depend on the oxidation state and that they may lead to unusual values of oxidation states for some transition metals. In 1990 IUPAC resorted to a postulatory (rule-based) method to determine the oxidation state. This was complemented by the synonymous term oxidation number as a descendant of the Stock number introduced in 1940 into the nomenclature.
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The reverse of disproportionation, such as when a compound in an intermediate oxidation state is formed from precursors of lower and higher oxidation states, is called comproportionation, also known as synproportionation.
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Since its discovery as a useful method of oxidation, Fétizon's reagent has been used in the total synthesis of numerous molecules such as (±)-bukittinggine. Fétizon's reagent has also been employed extensively in the study of various sugar chemistry, to achieve selective oxidation of tri and tetra methylated aldoses to aldolactones, oxidation of D-xylose and L-arabinose to D-threose and L-erythrose respectively, and oxidation of L-sorbose to afford L-threose among many others.
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Mechanism of oxidation of primary alcohols to carboxylic acids via aldehydes and aldehyde hydratesAlcohol oxidation is an important organic reaction. The indirect oxidation of primary alcohols to carboxylic acids normally proceeds via the corresponding aldehyde, which is transformed via an aldehyde hydrate (R-CH(OH)2) by reaction with water. The oxidation of a primary alcohol at the aldehyde level is possible by performing the reaction in absence of water, so that no aldehyde hydrate can be formed.
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Air oxidation of p-xylene gives p-toluic acid, which resists further air-oxidation. Conversion of p-toluic acid to methyl p-toluate (CH3C6H4CO2CH3) opens the way for further oxidation to monomethyl terephthalate, which is further esterified to dimethyl terephthalate. In 1955, Mid-Century Corporation and ICI announced the bromide- promoted oxidation of p-toluic acid to teraphthalic acid. This innovation enabled the conversion of p-xylene to terephthalic acid without the need to isolate intermediates.
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Unlike the Tamao oxidation whose starting material is an activated heteroatom-substituted silyl group, the Fleming oxidation utilizes a more robust silyl group which has only carbon atoms attached to the silicon atom. The prototype silyl structure that Fleming used was dimethylphenylsilyl. This aryl silane is then converted to the more reactive halo- or heterosilane to initiate the oxidation. The mechanism of the two-pot sequence differs from the Tamao oxidation since the reagents are different.
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Selenium is made available to the food chain through four oxidation and methylation processes. The first process is oxidation and methylation of inorganic and organic selenium by plant roots and microorganisms. The second process is biological mixing and associated oxidation of sediments from the burrowing of benthic invertebrates and feeding of fish and wildlife. The third process is represented by physical movement and chemical oxidation from water circulation and mixing, such as current, wind, precipitation, and upwelling.
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The formal oxidation state of the central nickel atom therefore ranges from +II to +IV in the above transformations (see Figure). However, the formal oxidation state is different from the real (spectroscopic) oxidation state based on the (spectroscopic) metal d-electron configuration. The stilbene-1,2-dithiolate behaves as a redox non-innocent ligand, and the oxidation processes actually take place at the ligands rather than the metal. This leads to the formation of ligand radical complexes.
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Cholesterol is susceptible to oxidation and easily forms oxygenated derivatives called oxysterols. Three different mechanisms can form these: autoxidation, secondary oxidation to lipid peroxidation, and cholesterol-metabolizing enzyme oxidation. A great interest in oxysterols arose when they were shown to exert inhibitory actions on cholesterol biosynthesis. This finding became known as the “oxysterol hypothesis”.
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The chromia provides oxidation and hot-corrosion resistance. The alumina controls oxidation mechanisms by limiting oxide growth by self- passivating. The yttrium enhances the oxide adherence to the substrate, and limits the growth of grain boundaries (which can lead to flaking of the coating). Investigation indicates that addition of rhenium and tantalum increases oxidation resistance.
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Oxidation of MCPA by hydroxyl radicals Oxidation of MCPA by positive holes h+ MCPA also could be photochemically degraded. Two scheme pathways can be proposed for the formation of the main intermediate, MCP. One scheme is MCPA oxidation by hydroxyl radical, •OH. The hydroxyl radical adds on the ring, followed by radical transfer to the ether carbon.
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Bhargava, S.K.; Tardio, J.; Prasad, J.; Folger, K.; Akolekar, D.B.; Grocott, S.C. Wet Oxidation and Catalytic Wet Oxidation. Ind. Eng. Chem. Res. 2006, 45, 1221-1258.Kolaczkowski, S.T.; Plucinski, P.; Beltran, F.J.; Rivas, F.J.; McLurgh, D.B. Wet air oxidation: a review of process technologies and aspects in reactor design. Chemical Engineering Journal 1999 73, 143-160.
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Partial oxidation (POX) is a type of chemical reaction. It occurs when a substoichiometric fuel-air mixture is partially combusted in a reformer, creating a hydrogen-rich syngas which can then be put to further use, for example in a fuel cell. A distinction is made between thermal partial oxidation (TPOX) and catalytic partial oxidation (CPOX).
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Malonyl-CoA signals glucose utilization and it controls the entry and oxidation of long-chain fatty acids (LCFA) in the mitochondria. Circulating glucose in the liver stimulates its uptake. Glucose oxidation produces citrate which can be converted to malonyl- CoA by acetyl-CoA carboxylase. Malonyl-CoA inhibits the carnitine palmitoyltransferase (CPT) that controls the entry and oxidation of LCFA.
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The inhibition of MCD suppresses the oxidation of fatty acids and stimulates glucose oxidation. In a study on MCD deficient mice there was no difference in the oxidation of fatty acids and glucose in the heart under aerobic conditions. It is theorized that the overexpression of fatty acids being used makes up for the lack of MCD.
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Once inside the mitochondrial matrix, the fatty acyl-CoA derivatives are degraded by a series of reactions that release acetyl-CoA and leads to the production of NADH and FADH2. There are four steps in fatty acid oxidation pathway; oxidation, hydration, oxidation, and thiolysis. It requires 7 rounds of this pathway to degrade palmitate (a C16 fatty acid).
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Niobium is attacked by hydrofluoric acid and hydrofluoric/nitric acid mixtures. Although niobium exhibits all of the formal oxidation states from +5 to −1, the most common compounds have niobium in the +5 state. Characteristically, compounds in oxidation states less than 5+ display Nb–Nb bonding. In aqueous solutions, niobium only exhibit the +5 oxidation state.
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Partial oxidation (POX) is a type of chemical reaction. It occurs when a substoichiometric fuel-air mixture is partially combusted in a reformer, creating a hydrogen-rich syngas which can then be put to further use, for example in a fuel cell. A distinction is made between thermal partial oxidation (TPOX) and catalytic partial oxidation (CPOX).
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The Sarett oxidation is an organic reaction that oxidizes primary and secondary alcohols to aldehydes and ketones, respectively, using chromium trioxide and pyridine. Unlike the similar Jones oxidation, the Sarett oxidation will not further oxidize primary alcohols to their carboxylic acid form, neither will it affect carbon-carbon double bonds.Margareta Avram (1983). "Chimie organica" p. 472.
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SeO2 is an important reagent in organic synthesis. Oxidation of paraldehyde (acetaldehyde trimer) with SeO2 gives glyoxal and the oxidation of cyclohexanone gives cyclohexane-1,2-dione. The selenium starting material is reduced to selenium, and precipitates as a red amorphous solid which can easily be filtered off. This type of reaction is called a Riley oxidation.
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Rhenium is present as the Re(VII) oxidation state as ReO4− within oxic conditions, but is reduced to Re(IV) which may form ReO2 or ReS2. Uranium is in oxidation state VI in UO2(CO3)34−(aq) and is found in the reduced form UO2(s). Vanadium is in several forms in oxidation state V(V); HVO42− and H2VO4−.
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Ferrous materials, including steel, may be somewhat protected by promoting oxidation ("rust") and then converting the oxidation to a metalophosphate by using phosphoric acid and further protected by surface coating. (See: Passivation (chemistry)).
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The most common oxidation state of nickel is +2, but compounds of Ni0, Ni+, and Ni3+ are well known, and the exotic oxidation states Ni2−, Ni1−, and Ni4+ have been produced and studied.
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Metal ions may also be agents of oxidation and reduction.
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The pressure of the ambient gas also affects oxidation rate.
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It employs one cofactor, NADP+ in a direct oxidation mechanism.
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Less commonly, it may indicate a fatty acid oxidation disorder.
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More than 20 human genetic defects in fatty acid transport or oxidation have been identified. In case of Fatty acid oxidation defects, acyl-carnitines accumulate in mitochondria and are transferred into the cytosol, and then into the blood. Plasma levels of acylcarnitine in newborn infants can be detected in a small blood sample by tandem mass spectrometry. When β oxidation is defective because of either mutation or deficiency in carnitine, the ω oxidation of fatty acids becomes more important in mammals.
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To fix a mole of carbon during the hydrogen oxidation, one third of the energy necessary for the sulphide oxidation is used. This is due to the redox potential of hydrogen, which is more negative than NAD (P)/H. Based on the amount of sulphide, hydrogen and other farm biotics, this phenomenon can be intensified leading, in some cases, to an energy production by oxidation of the hydrogen of 10 -18 times higher than produced one by the sulphide oxidation.
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Electrochemical experiments show that (+)-catechin oxidation mechanism proceeds in sequential steps, related with the catechol and resorcinol groups and the oxidation is pH-dependent. The oxidation of the catechol 3',4'-dihydroxyl electron-donating groups occurs first, at very low positive potentials, and is a reversible reaction. The hydroxyl groups of the resorcinol moiety oxidised afterwards were shown to undergo an irreversible oxidation reaction. The laccase/ABTS system oxidizes (+)-catechin to oligomeric products of which proanthocyanidin A2 is a dimer.
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Catalytic oxidation are processes that oxidize compounds using catalysts. Common applications involve oxidation of organic compounds by the oxygen in air. Such processes are conducted on a large scale for the remediation of pollutants, production of valuable chemicals, and the production of energy.Gerhard Franz, Roger A. Sheldon "Oxidation" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2000 In petrochemistry, high- value intermediates such as carboxylic acids, aldehydes, ketones, epoxides, and alcohols are obtained by partial oxidation of alkanes and alkenes with dioxygen.
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Half reactions are often used as a method of balancing redox reactions. For oxidation-reduction reactions in acidic conditions, after balancing the atoms and oxidation numbers, one will need to add H+ ions to balance the hydrogen ions in the half reaction. For oxidation-reduction reactions in basic conditions, after balancing the atoms and oxidation numbers, first treat it as an acidic solution and then add OH− ions to balance the H+ ions in the half reactions (which would give H2O).
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For pure elements, the oxidation state is zero. The oxidation state of an atom does not represent the "real" charge on that atom, or any other actual atomic property. This is particularly true of high oxidation states, where the ionization energy required to produce a multiply positive ion is far greater than the energies available in chemical reactions. Additionally, oxidation states of atoms in a given compound may vary depending on the choice of electronegativity scale used in their calculation.
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Introductory chemistry uses postulates: the oxidation state for an element in a chemical formula is calculated from the overall charge and postulated oxidation states for all the other atoms. A simple example is based on two postulates, #OS = +1 for hydrogen #OS = −2 for oxygen where OS stands for oxidation state. This approach yields correct oxidation states in oxides and hydroxides of any single element, and in acids such as H2SO4 or H2Cr2O7. Its coverage can be extended either by a list of exceptions or by assigning priority to the postulates. The latter works for H2O2 where the priority of rule 1 leaves both oxygens with oxidation state −1.
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In biomolecules, oxazoles result from the cyclization and oxidation of serine or threonine nonribosomal peptides: :Where X = H, for serine and threonine respectively, B = base. (1) Enzymatic cyclization. (2) Elimination. (3) [O] = enzymatic oxidation.
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Oxidation (link is dead). Wine International. URL accessed on 2 April 2006. Apart from phenolic oxidation, the ethanol present within wine can also be oxidised into other compounds responsible for flavour and aroma taints.
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Oxidation of Disulfoton happens rapidly and metabolizes disulfoton into sulfones and sulfoxides, oxidation to oxygen analogs and/or hydrolysis to produce a corresponding phosphorothionate or phosphate. Microsomal enzymes are being inhibited during the metabolism.
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The phosphorus in PCl3 is often considered to have the +3 oxidation state and the chlorine atoms are considered to be in the −1 oxidation state. Most of its reactivity is consistent with this description.
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Elements in a high oxidation state can have a valence higher than four. For example, in perchlorates, chlorine has seven valence bonds; ruthenium, in the +8 oxidation state in ruthenium tetroxide, has eight valence bonds.
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Next the oxidation catalyst oxidizes the hydrocarbons and carbon monoxide to form carbon dioxide and water.Catalytic Converter at Wikipedia.org Platinum is used in both the reduction and the oxidation catalysts.How Catalytic Converters Work at howstuffworks.
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After oxidation and methylation by SAM, (S)-reticuline 4 is formed. (S)-reticuline serves as a pivotal intermediate to other alkaloids. Oxidation of the tertiary amine then occurs and an iminium ion is formed 5.
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While introductory levels of chemistry teaching use postulated oxidation states, the IUPAC recommendation and the Gold Book entry list two entirely general algorithms for the calculation of the oxidation states of elements in chemical compounds.
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This product eliminates the need for radioactivity in fatty acid oxidation.
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Mechanism of Saegusa oxidation. Ligated acetate groups are omitted for clarity.
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Decanal can be prepared by oxidation of the related alcohol decanol.
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POMs are employed as commercial catalysts for oxidation of organic compounds.
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Oxidation of vanillin to the carboxylic acid occurred in ~88% yield.
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It is also hypothesized that oxidation plays a role in trafficking.
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Because there is a relatively small difference in the energy of the different d-orbital electrons, the number of electrons participating in chemical bonding can vary. The d-block elements have a tendency to exhibit two or more oxidation states, differing by multiples of one. The most common oxidation states are +2 and +3. Chromium, iron, molybdenum, ruthenium, tungsten, and osmium can have oxidation numbers as low as −4; iridium holds the singular distinction of being capable of achieving an oxidation state of +9.
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Generally the Chemiluminescence is in the short wave range, however, in some cases it is detected in infra-red (IR) region of light spectrum. Regardless of the emitted light wavelength, in Chemiluminescence the intensity of light is measured and is then correlated to the progression of the oxidation process. Chemiluminescence (CL) light intensity can be measured at various isothermal oxidation cycles; however, the temperature need not be raised to high levels. Correlation of light intensity is made to oxidation process parameters such as Oxidation Induction Temperature (OIT).
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The Fleming–Tamao oxidation, or Tamao–Kumada–Fleming oxidation, converts a carbon–silicon bond to a carbon–oxygen bond with a peroxy acid or hydrogen peroxide. Fleming–Tamao oxidation refers to two slightly different conditions developed concurrently in the early 1980s by the Kohei Tamao and Ian Fleming research groups. Summary of the Fleming–Tamao oxidation The reaction is stereospecific with retention of configuration at the carbon–silicon bond. This allows the silicon group to be used as a functional equivalent of the hydroxyl group.
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After oral ingestion, senecionine is absorbed from the gastrointestinal tract. When it reaches the liver, it is metabolized via three pathways: N-oxidation, oxidation, and ester hydrolysis. N-oxidation and hydrolysis are detoxification pathways, and the products of these reactions are conjugated and excreted by the kidneys. However, the N-oxide may be converted back into senecionine by cytochrome P-450 (CYP450) monooxygenases.
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In oxidative tissues, such as the skeletal muscle and the heart, the ratio of ACC2 expressed is higher. ACC1 and ACC2 are both highly expressed in the liver where both fatty acid oxidation and synthesis are important. The differences in tissue distribution indicate that ACC1 maintains regulation of fatty acid synthesis whereas ACC2 mainly regulates fatty acid oxidation (beta oxidation).
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His research has been focused on alkaloids, preparative electrochemistry, and oxidation chemistry . Additional research interests included the synthesis of nitrogen heterocycles, thin-layer chromatography, electrolytic oxidation and oxoammonium salt oxidation of alcohols with stoichiometric amounts of the Bobbitt recyclable salt. Particular attention is called to the Bobbitt reaction for the synthesis of tetrahydroisoquinoline and its derivatives in 1965 and following papers.
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Combined reforming is a combination of partial oxidation and steam reforming and is the last reaction that is used for hydrogen production. The general equation is given below: and are the stoichiometric coefficients for steam reforming and partial oxidation, respectively. The reaction can be both endothermic and exothermic determined by the conditions, and combine both the advantages of steam reforming and partial oxidation.
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Europium was isolated in 1901 and is named after the continent of Europe. Being a typical member of the lanthanide series, europium usually assumes the oxidation state +3, but the oxidation state +2 is also common. All europium compounds with oxidation state +2 are slightly reducing. Europium has no significant biological role and is relatively non-toxic compared to other heavy metals.
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Afterwards, the tea undergoes a withering process, either outside, indoors, or a combination of both. The leaves are then tossed and bruised on large bamboo baskets, which begins the oxidation process. Final rolling is undertaken, either by hand or by machine. A final firing sets the oxidation typically somewhere between 15%-30% oxidation, sometimes over charcoal, giving the tea a toasty, woody flavor.
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Quinone was originally prepared industrially by oxidation of aniline, for example by manganese dioxide. This method is mainly practiced in PRC where environmental regulations are more relaxed. Oxidation of hydroquinone is facile. One such method makes use of hydrogen peroxide as the oxidizer and iodine or an iodine salt as a catalyst for the oxidation occurring in a polar solvent; e.g.
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It has virtually no activity for ethanol oxidation, but exhibits high activity for oxidation of long-chain primary alcohols and for oxidation of S-hydroxymethyl-glutathione, a spontaneous adduct between formaldehyde and glutathione. This enzyme is an important component of cellular metabolism for the elimination of formaldehyde, a potent irritant and sensitizing agent that causes lacrymation, rhinitis, pharyngitis, and contact dermatitis.
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As it functions in the step immediately preceding the actual beta- oxidation and forms a double bond extending from the beta-carbon (position 2), enoyl-CoA isomerase is involved in both the NADPH-dependent and NADPH- independent pathways of beta-oxidation. The double bond serves as the target of oxidation and carbon-to-carbon bond cleavage, thereby shortening the fatty acid chain.
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AN OIL RIG CAT: At the ANode, Oxidation Involves Loss of electrons. Reduction Involves Gaining electrons at the CAThode. LOAN - Left Anode Oxidation Negative. In written representation of galvanic cell, anode is written on the left.
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Methanol→Partial oxidation(POX)/Autothermal reforming (ATR)→Water gas shift reaction (WGS)→preferential oxidation (PROX) The methanol reformer converts methanol to H2 and CO2, a reaction that occurs at temperatures of 250 °C to 300 °C.
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Thiosulfate is produced by the reaction of sulfite ion with elemental sulfur, and by incomplete oxidation of sulfides (pyrite oxidation), sodium thiosulfate can be formed by disproportionation of sulfur dissolving in sodium hydroxide (similar to phosphorus).
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Polypropylene: The Definitive User's Guide and Databook. Norwich, New York: Plastics Design Library, 1998. 105. It also prevents chemical oxidation by oxygen in normal air. An example is the rancidification (caused by oxidation) of edible oils.
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In “Analysis of two formaldehyde oxidation pathways in Methylobacillus flagellatus KT strain, a ribulose monophosphate cycle methylotroph” Chistoserdova et al. studied different pathways of formaldehyde oxidation in M. flagellatus KT strain to asset the importance of these pathways relating to dissimilatory metabolism, and, or formaldehyde detoxification. Based on null mutant experiments of 6-phosphogluconate dehydrogenase (Gnd) (a key enzyme of the cyclic oxidation pathway), and methenyl H4MPT cyclohydrolase (CH) (participating in the direct oxidation of formaldehyde via H4MPT derivatives), Chistoserdova et al. have found that Gnd null mutants were not obtained, but CH null mutants were obtained. The experimental result suggests “that this pathway [cyclic oxidation] is essential for growth on methylotrophic substrates”,Chistoserdova L, Gomelsky L, Vorholt JA, Gomelsky M, Tsygankov YD, Lidstrom ME. “Analysis of two formaldehyde oxidation pathways in Methylobacillus flagellatus KT, a ribulose monophosphate cycle methylotroph” Microbiology. 2000.
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On the right, higher oxidation states tend to become less stable going down a group. The shift between these trends is continuous: for example, group 3 also has lower oxidation states most stable in its lightest member (scandium, with CsScCl3 for example known in the +2 state), and group 12 is predicted to have copernicium more readily showing oxidation states above +2. The lanthanides positioned along the south of the table are distinguished by having the +3 oxidation state in common; this is their most stable state. The early actinides show a pattern of oxidation states somewhat similar to those of their period 6 and 7 transition metal congeners; the later actinides are more similar to the lanthanides, though the last ones (excluding lawrencium) have an increasingly important +2 oxidation state that becomes the most stable state for nobelium.
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Biochemically, ammonia oxidation occurs by the stepwise oxidation of ammonia to hydroxylamine () by the enzyme ammonia monooxygenase in the cytoplasm, followed by the oxidation of hydroxylamine to nitrite by the enzyme hydroxylamine oxidoreductase in the periplasm. Electron and proton cycling are very complex but as a net result only one proton is translocated across the membrane per molecule of ammonia oxidized. Nitrite oxidation is much simpler, with nitrite being oxidized by the enzyme nitrite oxidoreductase coupled to proton translocation by a very short electron transport chain, again leading to very low growth rates for these organisms. Oxygen is required in both ammonia and nitrite oxidation, meaning that both nitrosifying and nitrite-oxidizing bacteria are aerobes.
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Sodium dichromate oxidation gave carboxylic acid 25, Diazomethane treatment gave methyl ester 26 and sodium borohydride the allyl alcohol 27. Chiral resolution of this racemic compound with digitonin produced chiral 28 and on Oppenauer oxidation chiral 29.
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N-Hydroxyphthalimide is the N-hydroxy derivative of phthalimide. The compound is used, inter alia, as catalyst for oxidation reactions, in particular for the selective oxidation (e. g. alkanes to alcohols) with molecular oxygen under mild conditions.
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Evaluation of its metabolic pathway revealed N‐oxidation, aryl hydroxylation and subsequent O‐methylation, alkyl hydroxylation, oxidation, and degradation of the ethyl‐bridge yielding the O/N‐bis‐dealkylated metabolite, combinations thereof and further glucuronidation or sulfations.
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Pentagalloyl glucose can undergo oxidation reactions which are depending on the pH.
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The process has two modes, a reduction mode and an oxidation mode.
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The original Oppenauer oxidation employed aluminium butoxide in place of the isopropoxide.
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The effects of temperature are treated in the oxidation and creep terms..
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Dibromodiethyl sulfoxide is produced from dibromodiethyl sulfide by oxidation by benzoyl peroxide.
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Dibromodiethyl sulfone is produced from dibromodiethyl sulfide by oxidation by chromic acid.
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Naphthalene on oxidation with potassium permanganate or potassium dichromate gives phthalic acid.
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Pyridine aldehydes are typically prepared by oxidation of the hydroxymethyl- or methylpyridines.
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Dimethyl sulfide, a byproduct of the Swern oxidation, is one of the strongest odours known in organic chemistry. Humans can detect this compound in concentrations as low as 0.02 to 0.1 parts per million. A simple remedy for this problem is to rinse used glassware with bleach or oxone solution, which will oxidize the dimethyl sulfide back to dimethyl sulfoxide or to dimethyl sulfone, both of which are odourless and nontoxic. The reaction conditions allow oxidation of acid- sensitive compounds, which might decompose under the acidic oxidation conditions such as Jones oxidation.
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Using a 6Å x 6Å x 6Å box with the uranium atom in the centre, the bond valence calculation was performed for both U1 and U2 in solid. It was found, using the parameters for U(VI), that the calculated oxidation states for U1 and U2 are 5.11 and 5.10. Using the parameters for U(IV), the calculated oxidation states are 5.78 and 5.77 for U1 and U2, respectively. These studies suggests that all the uranium atoms have the same oxidation state, so that the oxidation states are disordered through the lattice.
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Electrochemical reactions in water are better understood by balancing redox reactions using the ion- electron method where H+, OH− ion, H2O and electrons (to compensate the oxidation changes) are added to cell's half-reactions for oxidation and reduction.
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Chemical (including electrochemical) oxidation is used to remove some persistent organic pollutants and concentrations remaining after biochemical oxidation.Weber, pp.363-408 Disinfection by chemical oxidation kills bacteria and microbial pathogens by adding ozone, chlorine or hypochlorite to wastewater.
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Chlorous acid is an inorganic compound with the formula HClO2. It is a weak acid. Chlorine has oxidation state +3 in this acid. The pure substance is unstable, disproportionating to hypochlorous acid (Cl oxidation state +1) and chloric acid (Cl oxidation state +5): : 2 HClO2 → HClO + HClO3 Although the acid is difficult to obtain in pure substance, the conjugate base, chlorite, derived from this acid is stable.
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This is due to possibilities of parallel reactions forming at high temperatures that otherwise would not exist at lower service environment. Traditionally, oxidation induction time (OIT) and/or oxidation onset temperature (OOT) methods are used to predict the behavior of a materials' oxidation. These properties are typically found using differential scanning calorimetry (DSC). However, these options use elevated temperatures which limit their use for adhesives and polymers.
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Actually, the ω Oxidation of Fatty Acids is another pathway for F-A degradation in some species of vertebrates and mammals that occurs in the endoplasmic reticulum of liver and kidney, it is the oxidation of the ω (omega) carbon—the carbon most far from the carboxyl group (in contrast to \beta oxidation which occurs at the carboxyl end of fatty acid, in the mitochondria).
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Transition metal clusters are frequently composed of refractory metal atoms. In general metal centers with extended d-orbitals form stable clusters because of favorable overlap of valence orbitals. Thus, metals with a low oxidation state for the later metals and mid-oxidation states for the early metals tend to form stable clusters. Polynuclear metal carbonyls are generally found in late transition metals with low formal oxidation states.
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Lindgren oxidation is a selective method for oxidizing aldehydes to carboxylic acids. The reaction is named after Bengt O. Lindgren. The oxidation takes place in water containing solvent mixtures under slightly acidic conditions (pH 3-5) with sodium chlorite as oxidizer. To avoid complicated oxidation reactions the hypochlorite, which is formed in the reaction, has to be removed from the reaction mixture by scavengers.
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Mechanism of oxidation of primary alcohols to carboxylic acids via aldehydes and aldehyde hydrates Reagents useful for the transformation of primary alcohols to aldehydes are normally also suitable for the oxidation of secondary alcohols to ketones. These include Collins reagent and Dess-Martin periodinane. The direct oxidation of primary alcohols to carboxylic acids can be carried out using potassium permanganate or the Jones reagent.
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Direct oxidation of ethylene was patented by Lefort in 1931. This method was repeatedly modified for industrial use, and at least four major variations are known. They all use oxidation by oxygen or air and a silver-based catalyst, but differ in the technological details and hardware implementations. Union Carbide (currently a division of Dow Chemical Company) was the first company to develop the direct oxidation process.
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It is prepared by oxidising selenium compounds in lower oxidation states. One method involves the oxidation of selenium dioxide with hydrogen peroxide: : + → . Unlike the production sulfuric acid by hydration of sulfur trioxide, the hydration of selenium trioxide is an impractical method. Instead, selenic acid may also be prepared by the oxidation of selenous acid () with halogens, such as chlorine or bromine, or with potassium permanganate.
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In analytical chemistry, this salt is the preferred source of ferrous ions as the solid has a long shelf life, being resistant to oxidation. This stability extends somewhat to solutions reflecting the effect of pH on the ferrous/ferric redox couple. This oxidation occurs more readily at high pH. The ammonium ions make solutions of Mohr's salt slightly acidic, which slows this oxidation process.
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TiN-coated drill bit The +4 oxidation state dominates titanium chemistry, but compounds in the +3 oxidation state are also common. Commonly, titanium adopts an octahedral coordination geometry in its complexes, but tetrahedral TiCl4 is a notable exception. Because of its high oxidation state, titanium(IV) compounds exhibit a high degree of covalent bonding. Unlike most other transition metals, simple aquo Ti(IV) complexes are unknown.
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Ammonia is innocent in this transformation. :700px Redox non-innocent behavior of ligands is illustrated by nickel bis(stilbenedithiolate) ([Ni(S2C2Ph2)2]z), which exists in three oxidation states: z = 2-, 1-, and 0. If the ligands are always considered to be dianionic (as is done in formal oxidation state counting), then z = 0 requires that that nickel has a formal oxidation state of +IV.
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After oral ingestion, pyrrolizidine alkaloids are absorbed from the gastrointestinal tract. When they reach the liver, they are metabolized via three pathways: N-oxidation, oxidation, and ester hydrolysis. N-oxidation and hydrolysis are detoxification pathways, and the products of these reactions are conjugated and excreted by the kidneys. However, the N-oxide may be converted back into the pyrrolizidine by cytochrome P-450 (CYP450) monooxygenases.
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Hydroboration-oxidation (9-BBN / H2O2) gave alcohol 8 and subsequent Swern oxidation ketone 9. Reaction with LDA / PhNTf2 gave enol triflate 10 and the triflate group was removed in alkene 11 by reaction with Pd(OAc)2 and PPh3.
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Liquid Paraffin in a glass bottle Paraffin oxidation is a historical industrial process for the production of synthetic fatty acids.C. H. Gill, Ed. Meusel: XLI. On paraffin and the products of its oxidation. In: Journal of the Chemical Society.
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The product can be obtained also by oxidation of tartronic acid or glycerol.
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Oxidation of the molecule results in many hydroxy-, carboxy-, and N-oxide derivatives.
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It is a part of an electron transfer chain for Fe(II) oxidation.
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Coffee is often vacuum packed to prevent oxidation and lengthen its shelf life.
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2,5-Dihydroxycinnamic acid is produced by Elbs persulfate oxidation of o-Coumaric acid.
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Further oxidation using ozone and sodium hydroxide can produce yellow Am(OH)6.
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Lowered pH tends to increase cleavage rates by inhibiting methionine side chain oxidation.
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Alternatively the compound can be synthesized from salicylic acid via Elbs persulfate oxidation.
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The important reactions of are associated with its redox, both oxidation and reduction.
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Uranium tetrabromide is an inorganic chemical compound of uranium in oxidation state +4.
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Polyphenylene oxide is well known for oxidation. This can be viewed as follows.
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Classification of such a varied group of compounds is somewhat arbitrary. Compounds where nitrogen is not assigned −3 oxidation state are not included, such as nitrogen trichloride where the oxidation state is +3; nor are ammonia and its many organic derivatives.
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Enzymatic deficiency in alpha-oxidation (most frequently in phytanoyl-CoA hydroxylase) leads to Refsum's disease, in which the accumulation of phytanic acid and its derivatives leads to neurological damage. Other disorders of peroxisome biogenesis also prevent alpha-oxidation from occurring.
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Miray Bekbölet is a Turkish environmental chemist researching oxidation techniques, photocatalytic and photolytic reactions, adsorption/bio-oxidation processes in aquatic systems, and drinking water quality. She is a professor of environmental chemistry at the Boğaziçi University Institute of Environmental Sciences.
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C. acnes also provokes skin inflammation by altering the fatty composition of oily sebum. Oxidation of the lipid squalene by C. acnes is of particular importance. Squalene oxidation activates NF-κB (a protein complex) and consequently increases IL-1α levels.
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Europium (II) sulfide is the inorganic compound with the chemical formula EuS. It is a black, air-stable powder. Europium possesses an oxidation state of +II in europium sulfide, whereas the lanthanides exhibit a typical oxidation state of +III.C. Housecroft.
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Tin(II) bromide is a chemical compound of tin and bromine with a chemical formula of SnBr2. Tin is in the +2 oxidation state. The stability of tin compounds in this oxidation state is attributed to the inert pair effect.
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Tantalum forms compounds in oxidation states −III to +V. Most commonly encountered are oxides of Ta(V), which includes all minerals. The chemical properties of Ta and Nb are very similar. In aqueous media, Ta only exhibit the +V oxidation state.
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Hydrolysis of 3-chloro cyclohexene followed by oxidation of the cyclohexenol is yet another route. Cyclohexenone is produced industrially by catalytic oxidation of cyclohexene, for example with hydrogen peroxide and vanadium catalysts. Several patents describe diverse oxidizing agents and catalysts.
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Oxidation von Amiden mit N-Hydroxyphthalimid Efficient oxidation reactions of precursors of important basic chemicals are of particular technical interest. For example, ε-caprolactam can be prepared using NHPI from the so-called KA oil ("ketone- alcohol" oil, a mixture of cyclohexanol and cyclohexanone) which is obtained during the oxidation of cyclohexane. The reaction proceeds via cyclohexanol hydroperoxide which reacts with ammonia to give peroxydicyclohexylamine followed by a rearrangement in the presence of catalytic amounts of lithium chloride. Oxidation von KA-Öl zu Caprolactam The use of N-hydroxyphthalimide as a catalyst in the oxidation of KA oil avoids the formation of the undesirable by-product ammonium sulfate which is produced by the conventional ε-caprolactam synthesis (Beckmann rearrangement of cyclohexanone oxime with sulfuric acid).
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This also releases some of the leaf juices, which may aid in oxidation and change the taste profile of the tea. #Oxidation: For teas that require oxidation, the leaves are left on their own in a climate-controlled room where they turn progressively darker. This is accompanied by agitation in some cases. In this process the chlorophyll in the leaves is enzymatically broken down, and its tannins are released or transformed.
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Curium ions in solution almost exclusively assume the oxidation state of +3, which is the most stable oxidation state for curium.Penneman, p. 24 The +4 oxidation state is observed mainly in a few solid phases, such as CmO2 and CmF4. Aqueous curium(IV) is only known in the presence of strong oxidizers such as potassium persulfate, and is easily reduced to curium(III) by radiolysis and even by water itself.
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The Swern oxidation, named after Daniel Swern, is a chemical reaction whereby a primary or secondary alcohol is oxidized to an aldehyde or ketone using oxalyl chloride, dimethyl sulfoxide (DMSO) and an organic base, such as triethylamine. It is one of the many oxidation reactions commonly referred to as 'activated DMSO' oxidations. The reaction is known for its mild character and wide tolerance of functional groups. The Swern oxidation.
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The dication is kinetically stable. An example of a stable diatomic dication which is not formed by oxidation of a neutral diatomic molecule is the dimercury dication . An example of a polyatomic dication is , formed by oxidation of S8 and unstable with respect to further oxidation over time to form SO2. Many organic dications can be detected in mass spectrometry for example (a complex) and the acetylene dication .
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Nitrones are generated most often either by the oxidation of hydroxylamines or condensation of monosubstituted hydroxylamines with carbonyl compounds (ketones or aldehydes). The most general reagent used for the oxidation of hydroxylamines is mercury(II) oxide. 250px Carbonyl condensation methods avoid issues of site selectivity associated with the oxidation of hydroxylamines with two sets of (alpha) hydrogens.File:NitrMech2.png A significant problem associated with many reactive nitrones is dimerization.
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One small but illustrative use is its use in the walls of self-cleaning ovens as a hydrocarbon oxidation catalyst during the high-temperature cleaning process. Another small scale but famous example is its role in oxidation of natural gas in gas mantles. Coleman white gas lantern mantle. The glowing element is mainly ThO2 doped with CeO2, heated by the Ce-catalyzed oxidation of the natural gas with air.
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The Parikh–Doering oxidation is an oxidation reaction that transforms primary and secondary alcohols into aldehydes and ketones, respectively. The procedure uses dimethyl sulfoxide (DMSO) as the oxidant, activated by the sulfur trioxide pyridine complex in the presence of triethylamine base. The Parikh–Doering oxidation. The reaction can be run at mild temperatures, often between 0 °C and room temperature, without formation of significant amounts of methyl thiomethylether side products.
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If problems of availability of the element could be overcome, then CfBr2 and CfI2 would likely be stable. The +3 oxidation state is represented by californium(III) oxide (yellow-green, Cf2O3), californium(III) fluoride (bright green, CfF3) and californium(III) iodide (lemon yellow, CfI3). Other +3 oxidation states include the sulfide and metallocene. Californium(IV) oxide (black brown, CfO2), californium(IV) fluoride (green, CfF4) represent the IV oxidation state.
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Myoglobin contains hemes, pigments responsible for the colour of red meat. The colour that meat takes is partly determined by the degree of oxidation of the myoglobin. In fresh meat the iron atom is in the ferrous (+2) oxidation state bound to an oxygen molecule (O2). Meat cooked well done is brown because the iron atom is now in the ferric (+3) oxidation state, having lost an electron.
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Chromium(III) oxide () is used as a colorant in ceramic glazes. Chromium(III) oxide can undergo a reaction with calcium oxide (CaO) and atmospheric oxygen in temperatures reached by a kiln to produce calcium chromate (). The oxidation reaction changes chromium from its +3 oxidation state to its +6 oxidation state. Chromium(VI) is very soluble and the most mobile out of all the other stable forms of chromium.
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Sulfur oxidation involves the oxidation of reduced sulfur compounds (such as sulfide ), inorganic sulfur (S), and thiosulfate () to form sulfuric acid (). A classic example of a sulfur-oxidizing bacterium is Beggiatoa, a microbe originally described by Sergei Winogradsky, one of the founders of environmental microbiology. Another example is Paracoccus. Generally, the oxidation of sulfide occurs in stages, with inorganic sulfur being stored either inside or outside of the cell until needed.
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Acid-base, oxidation-reduction and specific adsorption characteristics are strongly dependent on the composition of the surface functional groups.Philippe Serp, José Luis Figueiredo, Carbon Materials for Catalysis, Wiley, – 2009, – 550 p. The surface of conventional activated carbon is reactive, capable of oxidation by atmospheric oxygen and oxygen plasma steam, and also carbon dioxide and ozone. Oxidation in the liquid phase is caused by a wide range of reagents (HNO3, H2O2, KMnO4).
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Oxidation itself was first studied by Antoine Lavoisier, who defined it as the result of reactions with oxygen (hence the name). The term has since been generalized to imply a formal loss of electrons. Oxidation states, called oxidation grades by Friedrich Wöhler in 1835, were one of the intellectual stepping stones that Dmitri Mendeleev used to derive the periodic table. Jensen gives an overview of the history up to 1938.
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Vinegar is produced when acetic acid bacteria act on alcoholic beverages such as wine. They are used to perform specific oxidation reactions through processes called “oxidative fermentations”, that creates vinegar as a byproduct. In the biotechnological industry, these bacteria's oxidation mechanism is exploited to produce a number of compounds such as l-ascorbic acid, dihydroxyacetone, gluconic acid, and cellulose.Mamlouk, D. & Gullo, M. Acetic Acid Bacteria: Physiology and Carbon Sources Oxidation.
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Other methods for treating water include UV disinfection, oxidation, and electrodialysis reversal for salinity.
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Albright-Goldman-Oxidation (Aldehyd) The reaction does not proceed further to the carboxylic acid.
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Antimonites can be compared to antimonates, which contain antimony in the +5 oxidation state.
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Antimony tribromide (SbBr3) is a chemical compound containing antimony in its +3 oxidation state.
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This gene encodes an enzyme operative in the beta oxidation system of the peroxisomes.
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In the heyns oxidation the oxidizing reagent is a combination of oxygen and platinum.
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Waste polystyrene takes hundreds of years to biodegrade and is resistant to photo-oxidation.
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In the Lummus Process, the oxidation of toluene to benzoic acid is conducted separately.
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Ultimately oxidation of methyl groups gives protons and carbon dioxide, as seen in combustion.
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Colorants which contain a carbonyl group as the chromophore are particularly vulnerable to oxidation.
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Praseodymium(III) bromide is hygroscopic. Praseodymium(III) bromide has an oxidation number of 3.
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Preservation: immediately packed in sealed, airproof, aluminum sachet avoiding oxidation by air and humidity.
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The effectiveness of the oxidation is contingent on the site lithology, the residence time of the oxidant, the amount of oxidant used, the presence of oxidizing materials other than the targeted contaminant, the degree of effective contact between the oxidant and the contaminant(s), and the kinetics of the oxidation reaction between the oxidant and contaminant. The soil and groundwater are tested both before and after oxidant application to verify the effectiveness of the process. Monitoring of gases given off during oxidation can also help determine if contaminants are being destroyed. Elevated levels of is an indicator of oxidation.
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When using oxalyl chloride as the dehydration agent, the reaction must be kept colder than −60 °C to avoid side reactions. With cyanuric chloride or trifluoroacetic anhydride instead of oxalyl chloride, the reaction can be warmed to −30 °C without side reactions. Other methods for the activation of DMSO to initiate the formation of the key intermediate 6 are the use of carbodiimides (Pfitzner–Moffatt oxidation), a sulfur trioxide pyridine complex (Parikh–Doering oxidation) or acetic anhydride (Albright-Goldman oxidation). The intermediate 4 can also be prepared from dimethyl sulfide and N-chlorosuccinimide (the Corey–Kim oxidation).
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H2 is an important electron donor in a particular environment: Hydrothermal vents. In this environment hydrogen oxidation represents a significant origin of energy, sufficient to conduct ATP synthesis and autotrophic CO2 fixation so hydrogen oxidizing bacteria are relevant in deep sea habitats. Among the main chemosynthetic reactions that take place in hydrothermal vents, the oxidation of the sulphide and the hydrogen one covers a central role. In particular, for autotrophic carbon fixation, hydrogen oxidation metabolism is more favored than the sulfide/thiosulfate oxidation, although less energy is released (only -237 kJ/mol compared to – 797 kJ/mol).
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Subsequent to physical or chemical processing, either top-down or bottom-up, to obtain initial silicon nanostructures, thermal oxidation steps are often applied in order to obtain materials with desired size and aspect ratio. Silicon nanowires exhibit a distinct and useful self-limiting oxidation behaviour whereby oxidation effectively ceases due to diffusion limitations, which can be modeled. This phenomenon allows accurate control of dimensions and aspect ratios in SiNWs and has been used to obtain high aspect ratio SiNWs with diameters below 5 nm. The self-limiting oxidation of SiNWs is of value towards lithium ion battery materials.
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Because of the ambiguity of the term valence,The Free Dictionary: valence other notations are currently preferred. Beside the system of oxidation numbers as used in Stock nomenclature for coordination compounds, and the lambda notation, as used in the IUPAC nomenclature of inorganic chemistry, oxidation state is a more clear indication of the electronic state of atoms in a molecule. The oxidation state of an atom in a molecule gives the number of valence electrons it has gained or lost. In contrast to the valency number, the oxidation state can be positive (for an electropositive atom) or negative (for an electronegative atom).
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Pyridinium dichromate (PDC) is a bright-orange solid with the formulae (C5H5NH)2Cr2O7 that is very often used for the oxidation of primary and secondary alcohols to aldehydes and ketones respectively. On the other hand, in 1979, Corey and Schmidt reported that reaction of saturated primary alcohols with PDC, using dimethylformamide (Me2NCHO, DMF) as solvent, results in oxidation to carboxylic acids rather than aldehydes. No oxidation to carboxylic acids occurs on allylic and benzylic primary alcohols. The procedure of Corey and Schmidt for the oxidation of saturated primary alcohols to carboxylic acids is run under essentially neutral conditions.
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Zetaproteobacteria are thought to live at the interface, where there is enough oxygen for use as an electron acceptor without there being too much oxygen for the organism to compete with the increased rate of chemical oxidation, and where there is enough ferrous iron for growth. Iron oxidation is not always energetically favorable. Reference discusses favorable conditions for iron oxidation in habitats that otherwise may have been thought to be dominated by the more energy yielding metabolisms of hydrogen or sulfur oxidation. Note: Iron is not the only reduced chemical species accociated with these redox gradient environments.
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Unlike most fatty acids, phytanic acid cannot be metabolized by β-oxidation. Instead, it undergoes α-oxidation in the peroxisome, where it is converted into pristanic acid by the removal of one carbon. Pristanic acid can undergo several rounds of β-oxidation in the peroxisome to form medium chain fatty acids that can be converted to carbon dioxide and water in mitochondria. Individuals with adult Refsum disease, an autosomal recessive neurological disorder caused by mutations in the PHYH gene, have impaired α-oxidation activity and accumulate large stores of phytanic acid in their blood and tissues.
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The development of this type of new measurement method was welcomed by the industry and proposed for an internationally valid standard measurement method. To this end, the measurement method had to be presented to the Technical Committees of standardization bodies such as ASTM International in the United States and accepted for the development of a new method. The procedure was published in 2009 by ASTM International and includes the methods for gasoline (ASTM D7525ASTM D7525 - 09 Standard Test Method for Oxidation Stability of Spark Ignition Fuel—Rapid Small Scale Oxidation Test (RSSOT)) and diesel, biodiesel and blends (ASTM D7545ASTM D7545 - 09 Standard Test Method for Oxidation Stability of Middle Distillate Fuels—Rapid Small Scale Oxidation Test (RSSOT)). A European standard for liquid petroleum products (EN 16091EN 16091 - Liquid petroleum products - Middle distillates and fatty acid methyl ester (FAME) fuels and blends - Determination of oxidation stability by rapid small scale oxidation method) was published in 2012 by CEN.
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Oxidation states can be useful for balancing chemical equations for oxidation–reduction (or redox) reactions, because the changes in the oxidized atoms have to be balanced by the changes in the reduced atoms. For example, in the reaction of acetaldehyde with Tollens' reagent to form acetic acid (shown below), the carbonyl carbon atom changes its oxidation state from +1 to +3 (loses two electrons). This oxidation is balanced by reducing two Ag+ cations to Ag0 (gaining two electrons in total). :600px An inorganic example is the Bettendorf reaction using SnCl2 to prove the presence of arsenite ions in a concentrated HCl extract. When arsenic(III) is present, a brown coloration appears forming a dark precipitate of arsenic, according to the following simplified reaction: : 2 As3+ \+ 3 Sn2+ → 2 As0 \+ 3 Sn4+ Here three tin atoms are oxidized from oxidation state +2 to +4, yielding six electrons that reduce two arsenic atoms from oxidation state +3 to 0.
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Describing the overall electrochemical reaction for a redox process requires a balancing of the component half-reactions for oxidation and reduction. In general, for reactions in aqueous solution, this involves adding H+, OH−, H2O, and electrons to compensate for the oxidation changes.
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222 Copper behaves like a transition metal in its preferred oxidation state of +2. Stable compounds in which copper is in its less preferred oxidation state of +1 (Cu2O, CuCl, CuBr, CuI and CuCN, for example) have significant covalent character.Vanderah 1992, p.
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The Boyland–Sims oxidation is the chemical reaction of anilines with alkaline potassium persulfate, which after hydrolysis forms ortho-hydroxyl anilines. The Boyland-Sims oxidation The ortho-isomer is formed predominantly. However, the para-sulfate is formed in small amounts with certain anilines.
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Thiosulfurous acid (HS−S(=O)−OH) is a hypothetical compound with the formula S2(OH)2. Attempted synthesis leads to polymers. It is a low oxidation state (+1) sulfur acid.+1 is the average oxidation state of the two structurally different sulfur atoms.
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The salt is prepared by the electrolytic oxidation of sodium hydrogen sulfate: :2 NaHSO4 → Na2S2O8 \+ H2 Oxidation is conducted at a platinum anode.Pietzsch, A.; Adolph, G. J. Chem. Technol. Biotechnol. 1911, 30, 85. In this way about 165,000 tons were produced in 2005.
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These reactions include the partial oxidation of a hydrocarbon by methane monooxygenase (MMO) or the oxidation and production of hydrogen by hydrogenase. "Functional" enzyme mimics or bioinspired catalysts are designed with characteristics of the enzyme in hopes of reproducing the enzymes functionality.
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Examples include the Catalytica system, copper zeolites, and iron zeolites stabilizing the alpha-oxygen active site. One group of bacteria drive methane oxidation with nitrite as the oxidant in the absence of oxygen, giving rise to the so-called anaerobic oxidation of methane.
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1,2-Benzoquinone is produced on oxidation of catechol exposed to air in aqueous solution or by ortho oxidation of a phenol. It is a precursor to melanin. A strain of the bacterium Pseudomonas mendocina metabolises benzoic acid, yielding 1,2-benzoquinone via catechol.
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The reaction is selective for oxidation of primary alcohols to aldehydes and generally does not oxidize secondary alcohols. Solutions for the Hoover–Stahl oxidation are commercially available from Millipore-Sigma, though the catalyst can be easily prepared in situ from common laboratory reagents.
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In 2016 Braunschweig isolated the first compounds of beryllium in the oxidation state of zero.
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Research is underway to genetically modify various organisms to improve their performance in biological oxidation.
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The oxidation was removed by laser, and the metal was sealed with a wax compound.
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The other half was awarded to K. Barry Sharpless for his work in oxidation reactions.
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Neutralization of these free radicals terminates the cycle of lipid oxidation that leads to rancidity.
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The oxidation mechanism ordinarily consists of a ligand exchange reaction followed by a reductive elimination.
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The preparation of sulfinic acids by the oxidation of thiols is difficult due to overoxidation.
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In the great majority of its compounds, tin has the oxidation state II or IV.
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Furthermore, secondary alcohols can undergo oxidation reactions. This results in the formation of a ketone.
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Oxidation can be achieved by heating the alcohol with an acidified solution of potassium dichromate. In this case, excess dichromate will further oxidize the aldehyde to a carboxylic acid, so either the aldehyde is distilled out as it forms (if volatile) or milder reagents such as PCC are used. :[O] + CH3(CH2)9OH → CH3(CH2)8CHO + H2O Oxidation of primary alcohols to form aldehydes can be achieved under milder, chromium-free conditions by employing methods or reagents such as IBX acid, Dess–Martin periodinane, Swern oxidation, TEMPO, or the Oppenauer oxidation. Another oxidation route significant in industry is the Wacker process, whereby ethylene is oxidized to acetaldehyde in the presence of copper and palladium catalysts (acetaldehyde is also produced on a large scale by the hydration of acetylene).
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Many enzymatic reactions are oxidation–reduction reactions, in which one compound is oxidized and another compound is reduced. The ability of an organism to carry out oxidation–reduction reactions depends on the oxidation–reduction state of the environment, or its reduction potential (E_h). Strictly aerobic microorganisms are generally active at positive E_h values, whereas strict anaerobes are generally active at negative E_h values. Redox affects the solubility of nutrients, especially metal ions.
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A disproportionation reaction is one in which a single substance is both oxidized and reduced. For example, thiosulfate ion with sulfur in oxidation state +2 can react in the presence of acid to form elemental sulfur (oxidation state 0) and sulfur dioxide (oxidation state +4). :S2O32-(aq) + 2 H+(aq) → S(s) + SO2(g) + H2O(l) Thus one sulfur atom is reduced from +2 to 0, while the other is oxidized from +2 to +4.
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Oxidation of one gram of carbohydrate yields approximately 16 kJ (4 kcal) of energy, while the oxidation of one gram of lipids yields about 38 kJ (9 kcal). The human body stores between 300 and 500 g of carbohydrates depending on body weight, with the skeletal muscle contributing to a large portion of the storage. Energy obtained from metabolism (e.g., oxidation of glucose) is usually stored temporarily within cells in the form of ATP.
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In addition to genetic tests involving the sequencing of PEX genes, biochemical tests have proven highly effective for the diagnosis of Zellweger syndrome and other peroxisomal disorders. Typically, Zellweger syndrome patients show elevated very long chain fatty acids in their blood plasma. Cultured primarily skin fibroblasts obtained from patients show elevated very long chain fatty acids, impaired very long chain fatty acid beta-oxidation, phytanic acid alpha- oxidation, pristanic acid alpha-oxidation, and plasmalogen biosynthesis.
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Biological oxidation system Biological oxidation of organic matters has led to the innovation of a low cost secondary treatment of the waste water emissions and industrial air emissions. The process of biodegradation offers a very fast method which typically offers 4,000 catalytic cycles per minute. Destruction rate efficiency is generally greater than 99% on most biodegratable organics emissions. The Biological oxidation technology is free from secondary emissions (NOx) with limited CO2 production.
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Lead(II) oxide is also soluble in alkali hydroxide solutions to form the corresponding plumbite salt. : PbO + 2 OH− \+ H2O → Chlorination of plumbite solutions causes the formation of lead's +4 oxidation state. : + Cl2 → PbO2 \+ 2 Cl− \+ 2 H2O Lead dioxide is representative of the +4 oxidation state, and is a powerful oxidizing agent. The chloride of this oxidation state is formed only with difficulty and decomposes readily into lead(II) chloride and chlorine gas.
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Chemical structure of gluconic acid, the aldonic acid derived from glucose. An aldonic acid is any of a family of sugar acids obtained by oxidation of the aldehyde functional group of an aldose to form a carboxylic acid functional group. Thus, their general chemical formula is HOOC-(CHOH)n-CH2OH. Oxidation of the terminal hydroxyl group instead of the terminal aldehyde yields a uronic acid, while oxidation of both terminal ends yields an aldaric acid.
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NiF2 is prepared by treatment of anhydrous nickel(II) chloride with fluorine at 350 °C:Priest, H. F. “Anhydrous Metal Fluorides” Inorganic Syntheses McGraw-Hill: New York, 1950; Vol. 3, pages 171-183. :NiCl2 \+ F2 -> NiF2 \+ Cl2 The corresponding reaction of cobalt(II) chloride results in oxidation of the cobalt, whereas nickel remains in the +2 oxidation state after fluorination because its +3 oxidation state is less stable. Chloride is more easily oxidized than nickel(II).
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Safrole can undergo many forms of metabolism. The two major routes are the oxidation of the allyl side chain and the oxidation of the methylenedioxy group. The oxidation of the allyl side chain is mediated by a cytochrome P450 complex, which will transform safrole into 1’-hydroxysafrole. The newly formed 1’-hydroxysafrole will undergo a phase II of drug metabolism reaction with a sulfotransferase enzyme to create 1’-sulfoxysafrole, which can cause DNA adducts.
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Ethanol can be oxidized to acetaldehyde and further oxidized to acetic acid, depending on the reagents and conditions. This oxidation is of no importance industrially, but in the human body, these oxidation reactions are catalyzed by the enzyme liver alcohol dehydrogenase. The oxidation product of ethanol, acetic acid, is a nutrient for humans, being a precursor to acetyl CoA, where the acetyl group can be spent as energy or used for biosynthesis.
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Oxidative stability is a measure of oil or fat resistance to oxidation. Because the process takes place through a chain reaction, the oxidation reaction has a period when it is relatively slow, before it suddenly speeds up. The time for this to happen is called the "induction time", and it is repeatable under identical conditions (temperature, air flow, etc.). There are a number of ways to measure the progress of the oxidation reaction.
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Each half-cell has a characteristic voltage. Various choices of substances for each half-cell give different potential differences. Each reaction is undergoing an equilibrium reaction between different oxidation states of the ions: When equilibrium is reached, the cell cannot provide further voltage. In the half-cell that is undergoing oxidation, the closer the equilibrium lies to the ion/atom with the more positive oxidation state the more potential this reaction will provide.
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2, pp. 118–132, Apr. 1970. is commonly referred to as the local oxidation of silicon (LOCOS) process. Areas which are not to be oxidized are covered with a film of silicon nitride, which blocks diffusion of oxygen and water vapor due to its oxidation at a much slower rate.A. Kuiper, M. Willemsen, J. M. G. Bax, and F. H. P. H. Habraken, “Oxidation behaviour of LPCVD silicon oxynitride films,” Applied Surface Science, vol.
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Separation of the crystalline hydrate may be performed by centrifuge or sedimentation and decanting. Water can be released from the hydrate crystals by heatingOsegovic, John P. et al. (2009) Hydrates for Gypsum Stack Water Purification. AIChE Annual Convention #In Situ Chemical Oxidation, a form of advanced oxidation processes and advanced oxidation technology, is an environmental remediation technique used for soil and/or groundwater remediation to reduce the concentrations of targeted environmental contaminants to acceptable levels.
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As a lot of the aforementioned conditions for the oxidations of primary alcohols to acids are harsh and not compatible with common protection groups, organic chemists often use a two-step procedure for the oxidation to acids. The primary alcohol is oxidized to an aldehyde using one of the many existing procedures (e.g. IBX oxidation, Dess–Martin periodinane). The aldehyde can then be subjected to the conditions of the Pinnick oxidation using sodium chlorite.
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IMC can be used for rapidly determining the rate of slow changes in industrial polymers. For example, gamma radiation sterilization of a material frequently used for surgical implants--ultra-high-molecular-weight polyethylene (UHMWPE)--is known to produce free radicals in the polymer. The result is slow oxidation and gradual undesirable embrittlement of the polymer on the shelf or in vivo. IMC could detect oxidation-related heat and quantified an oxidation rate of ca.
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The Hoover–Stahl oxidation explicitly indicates the earliest of the Stahl oxidation conditions allowing for the selective oxidation of primary alcohols. The system utilizes 2,2'-bipyridine (bpy), a copper(I) source (typically tetrakis(acetonitrile) copper(I) triflate, tetrafluoroborate, or hexafluorophosphate), TEMPO, and N-methylimidazole. The reaction is conducted in acetonitrile at room temperature under an atmosphere or air. Catalyst loadings are typically around 5 mol %, with N-methylimidazole being used at 10 mol %.
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In addition to genetic tests involving PEX genes, biochemical tests have proven highly effective for the diagnosis of infantile Refsum disease and other peroxisomal disorders. Typically, IRD patients show elevated very long chain fatty acids in their blood plasma. Cultured primarily skin fibroblasts obtained from patients show elevated very long chain fatty acids, impaired very long chain fatty acid beta-oxidation, phytanic acid alpha-oxidation, pristanic acid alpha-oxidation, and plasmalogen biosynthesis.
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After canceling, the equation is re-written as :2Mg(s) + O2(g) →2Mg2+ \+ 2O2− Two ions, positive (Mg2+) and negative (O2−) exist on product side and they combine immediately to form a compound magnesium oxide (MgO) due to their opposite charges (electrostatic attraction). In any given oxidation-reduction reaction, there are two half reactions—oxidation half reaction and reduction half reaction. The sum of these two half reactions is the oxidation–reduction reaction.
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Thus, the oxidation state of an atom in a compound is purely a formalism. It is nevertheless important in understanding the nomenclature conventions of inorganic compounds. Also, a number of observations pertaining to chemical reactions may be explained at a basic level in terms of oxidation states. In inorganic nomenclature, the oxidation state is represented by a Roman numeral placed after the element name inside a parenthesis or as a superscript after the element symbol.
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The phosphorus oxoacids can be classified by the oxidation state(s) of the phosphorus atom(s), which may vary from +1 to +5. The oxygen atoms are usually in oxidation state -2, but may be in state -1 if the molecule includes peroxide groups.
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Reactive sulfur species (RSS) are a family of sulfur-based chemical compounds that can oxidize and inhibit thiol-proteins and enzymes. They are often formed by the oxidation of thiols and disulfides into higher oxidation states. Examples of RSS include persulfides, polysulfides and thiosulfate.
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Industrial production of propylene oxide starts from propylene.Two general approaches are employed, one involving hydrochlorination and the other involving oxidation. In 2005, about half of the world production was through chlorohydrin technology and one half via oxidation routes. The latter approach is growing in importance.
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The exterior atom has an oxidation number of −1 while the central sulfur atom has the oxidation state of +3. It is the equivalent acid for disulfur monoxide. Salts derived from thiosulfurous acid, which are also unknown, are named "thiosulfites" or "sulfurothioites". The ion is .
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Potassium periodate can be prepared by the oxidation of an aqueous solution of potassium iodate by chlorine and potassium hydroxide. : It can also be generated by the electrochemical oxidation of potassium iodate, however the low solubility of KIO3 makes this approach of limited use.
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These alcohols react with chlorosulfuric acid: :ClSO3H + ROH → ROSO3H + HCl Alternatively, alcohols can be converted to the half sulfate esters using sulfur trioxide: :SO3 \+ ROH → ROSO3H Some organosulfates can be prepared by the Elbs persulfate oxidation of phenols and the Boyland–Sims oxidation of anilines.
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The oxidation of a methyl group occurs widely in nature and industry. The oxidation products derived from methyl are CH2OH, CHO, and CO2H. For example, permanganate often converts a methyl group to a carboxyl (–COOH) group, e.g. the conversion of toluene to benzoic acid.
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3-Hydroxyacyl CoA dehydrogenase is classified as an oxidoreductase. It is involved in fatty acid metabolic processes. Specifically it catalyzes the third step of beta oxidation; the oxidation of L-3-hydroxyacyl CoA by NAD+. The reaction converts the hydroxyl group into a keto group.
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Aldehydes are commonly generated by alcohol oxidation. In industry, formaldehyde is produced on a large scale by oxidation of methanol. Oxygen is the reagent of choice, being "green" and cheap. In the laboratory, more specialized oxidizing agents are used, but chromium(VI) reagents are popular.
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In redox reactions one reactant, the oxidant, lowers its oxidation state and another reactant, the reductant, has its oxidation state increased. The net result is an exchange of electrons. Electron exchange can occur indirectly as well, e.g., in batteries, a key concept in electrochemistry.
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Oxidation resistance protein 1 is a protein that in humans is encoded by the OXR1 gene.
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Ozonia manufactures ozone, ultraviolet (UV) and advanced oxidation process (AOP) technologies and systems for water treatment.
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"The Oxidation States of the Elements and Their Potentials in Aqueous Solution" ASIN B000GRXLSA published 1938.
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Online article and cyclohexanone oxidation to 1,2-cyclohexanedione.Organic Syntheses, Coll. Vol. 4, p. 229 (1963); Vol.
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Propyl gallate is an antioxidant. It protects against oxidation by hydrogen peroxide and oxygen free radicals.
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Typical aminophosphines undergo oxidation to the oxide. Alkylation, e.g. by methyl iodide, gives the phosphonium cation.
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In water oxidation catalysis, metal oxo complexes are intermediates in the conversion of water to O2.
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Oxidation by potassium permanganate affords picolinic acid: :350px Deprotonation with butyllithium affords C5H4NCH2Li, a versatile nucleophile.
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The XANES experiments done on plutonium in soil, concrete and standards of the different oxidation states.
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Unsymmetrical sulfides are prochiral, thus their oxidation gives chiral sulfoxides. This process can be performed enantioselectively.
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Dozens of ATP equivalents are generated by the beta-oxidation of a single long acyl chain.
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Flowchart, showing the Purex process and the likely oxidation state of neptunium in the process solution.
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Here she began working with electron microscopy to study silicon oxidation and the dynamics of dislocation.
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Alternatively, it arises from the oxidation of 4,4'-bis(aminophenyl)methane in the presence of aniline.
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Each oxidant offers advantages and disadvantages. Instead of using chemical oxidants, electrochemical oxidation is often possible.
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The CYP4F2 enzyme is involved in catalyzing the ω-oxidation and chain shortening of such acids.
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Nichrome alloys also have very good mechanical properties which allow for good oxidation and corrosion properties.
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The action is one of oxidation, the cellulose being transformed into a substance known as oxycellulose.
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Acetyl-CoA, on the other hand, derived from pyruvate oxidation, or from the beta-oxidation of fatty acids, is the only fuel to enter the citric acid cycle. With each turn of the cycle one molecule of acetyl-CoA is consumed for every molecule of oxaloacetate present in the mitochondrial matrix, and is never regenerated. It is the oxidation of the acetate portion of acetyl-CoA that produces CO2 and water, with the energy of O2 thus released captured in the form of ATP. The three steps of beta-oxidation resemble the steps that occur in the production of oxaloacetate from succinate in the TCA cycle.
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For complexes of intermediate oxidation states (+III, +IV), the [R3P=N]− ligand bridges pairs of metals. For metals in high oxidation states (+V to +VIII), the [R3P=N]− group exists exclusively as the terminal ligand. Most phosphinoimidate complexes fall into two groups, one with a linear or largely linear M-N-P bridge with bond angles between 161 and 177° and another with a bent M-N-P configuration with bond angles between 130 and 140°. Linear M-N-P arrangements are achieved mainly by metals in high oxidation states while metals with lower oxidation states are characterized by bent M-N-P arrangements.
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With some minor exceptions, oxidation numbers among the elements show four main trends according to their periodic table geographic location: left; middle; right; and south. On the left (groups 1 to 4, not including the f-block elements, and also niobium, tantalum, and probably dubnium in group 5), the highest most stable oxidation number is the group number, with lower oxidation states being less stable. In the middle (groups 3 to 11), higher oxidation states become more stable going down each group. Group 12 is an exception to this trend; they behave as if they were located on the left side of the table.
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Over thirty years ago, Shilov discovered the selective oxidization of alkanes in the presence of platinum-based metals. This was impractical because it required a stoichiometric oxidant in addition to the catalytic Pt(II) metal, which led Goldberg to inquire deeper into understanding C-H bond activation, oxidation, and C-heteroatom bond formation, leading to the development of more practical products. In recent studies of utilizing alkanes, Goldberg has investigated the functionalization of alkanes through oxidation reactions using platinum-based catalysts. 464x464px Pt(II) methyl complexes are key intermediates in both the Shilov methane oxidation system and in more recent catalytic Pt methane oxidation systems.
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Two of the most popular are "OIL RIG" (Oxidation Is Loss, Reduction Is Gain) and "LEO" the lion says "GER" (Lose Electrons: Oxidation, Gain Electrons: Reduction). Oxidation and reduction always occur in a paired fashion such that one species is oxidized when another is reduced. For cases where electrons are shared (covalent bonds) between atoms with large differences in electronegativity, the electron is assigned to the atom with the largest electronegativity in determining the oxidation state. The atom or molecule which loses electrons is known as the reducing agent, or reductant, and the substance which accepts the electrons is called the oxidizing agent, or oxidant.
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Antioxidants are an especially important class of preservatives as, unlike bacterial or fungal spoilage, oxidation reactions still occur relatively rapidly in frozen or refrigerated food. These preservatives include natural antioxidants such as ascorbic acid (AA, E300) and tocopherols (E306), as well as synthetic antioxidants such as propyl gallate (PG, E310), tertiary butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA, E320) and butylated hydroxytoluene (BHT, E321). The most common molecules attacked by oxidation are unsaturated fats; oxidation causes them to turn rancid. Since oxidized lipids are often discolored and usually have unpleasant tastes such as metallic or sulfurous flavors, it is important to avoid oxidation in fat-rich foods.
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The central metal ion is cobalt. As isolated as an air-stable solid and available commercially, cobalt in vitamin B12 (cyanocobalamin and other vitamers) is present in its +3 oxidation state. Biochemically, the cobalt center can take part in both two-electron and one-electron reductive processes to access the "reduced" (B12r, +2 oxidation state) and "super-reduced" (B12s, +1 oxidation state) forms. The ability to shuttle between the +1, +2, and +3 oxidation states is responsible for the versatile chemistry of vitamin B12, allowing it to serve as a donor of deoxyadenosyl radical (radical alkyl source) and as a methyl cation equivalent (electrophilic alkyl source).
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Iron oxidation pathways in both acidophilic and circumneutral freshwater iron oxidation habitats, such as acid mine drainage or groundwater iron seeps, respectively, are better understood than marine circumneutral iron oxidation. In recent years, researchers have made progress in suggesting possibilities for how the Zetaproteobacteria oxidize iron, primarily through comparative genomics. With this technique, genomes from organisms with similar function, for example the freshwater Fe-oxidizing Betaproteobacteria and the marine Fe-oxidizing Zetaproteobacteria, are compared to find genes that may be required for this function. Identifying the iron oxidation pathway in the Zetaproteobacteria began with the publication of the first described cultured representative, M. ferrooxydans strain PV-1.
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See for example, In coordination chemistry, phenylenediamine is an important ligand precursor. Schiff base derivatives, such as those derived from salicylaldehyde, are excellent chelating ligands. Oxidation of its metal-phenylenediamine complexes affords the diimine derivatives, which are intensely colored and often exist in multiple stable oxidation states.
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Experiments involving this microbial conversion resulted in high yields: 98% from 2-furfuryl alcohol and 88% from 2-furanaldehyde. Oxidation with N. corallina is unique because most other microorganisms produce two products from the oxidation, the acid and the alcohol. Furthermore, aromatic ring destruction does not occur.
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In vivo, adrenochrome is synthesized by the oxidation of epinephrine. In vitro, silver oxide (Ag2O) is used as an oxidizing agent.MacCarthy, Chim, Ind. Paris 55,435(1946) In solution, adrenochrome is pink and further oxidation of the compound causes it to polymerize into brown or black melanin compounds.
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The alcohol dehydrogenases comprise a group of several isozymes that catalyse the oxidation of primary and secondary alcohols to aldehydes and ketones, respectively, and also can catalyse the reverse reaction. In mammals this is a redox (reduction/oxidation) reaction involving the coenzyme nicotinamide adenine dinucleotide (NAD+).
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Cable bacteria allow for long distance electron transport, which connects electron donors to electron acceptors, connecting previously separated oxidation and reduction reactions. Cable bacteria couple the reduction of oxygen or nitrate at the sediment's surface to the oxidation of sulfide in the deeper, anoxic, sediment layers.
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Hypochlorite (ClO−) A hypohalite is an oxyanion containing a halogen in oxidation state +1. This includes hypoiodite, hypobromite and hypochlorite. In hypofluorite (oxyfluoride) the fluorine atom is in a −1 oxidation state. Hypohalites are also encountered in organic chemistry, often as acyl hypohalites (see the Hunsdiecker reaction).
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Photo- aging is another degradation route for polycarbonates. Polycarbonate molecules (such as the aromatic ring) absorb UV radiation. This absorbed energy causes cleavage of covalent bonds which initiates the photo-aging process. The reaction can be propagated via side chain oxidation, ring oxidation or photo- Fries rearrangement.
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Chemical bleaching is achieved by oxidation or reduction. Oxidation can destroy the dye completely, e.g. through the use of sodium hypochlorite (NaClO, common bleach) or hydrogen peroxide.XP-Chloro Degradation Malachite green Reduction of methyl violet occurs in microorganisms but can be attained chemically using sodium dithionite.
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Structure of the antioxidant glutathione. Antioxidants are compounds that inhibit oxidation. Oxidation is a chemical reaction that can produce free radicals, thereby leading to chain reactions that may damage the cells of organisms. Antioxidants such as thiols or ascorbic acid (vitamin C) terminate these chain reactions.
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Oxidation with in the presence of vanadium pentoxide as catalyst gives phthalic anhydride: :C10H8 \+ 4.5 O2 → C6H4(CO)2O + 2 CO2 \+ 2 H2O This reaction is the basis of the main use of naphthalene. Oxidation can also be effected using conventional stoichiometric chromate or permanganate reagents.
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In a fuel cell, the oxidation of any fuel requires the use of a catalyst in order to achieve the current densities required for commercially viable fuel cells, and platinum- based catalysts are some of the most efficient materials for the oxidation of small organic molecules.
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Two important properties are pH and oxidation-reduction potential (Eh). For example, the sulfate mineral jarosite forms only in low pH (highly acidic) water. Phyllosilicates usually form in water of neutral to high pH (alkaline). Eh is a measure is the oxidation state of an aqueous system.
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D. Appleton and Co., New York. or from glycerin diacetate and concentrated nitric acid in the cold. The product can be obtained also by oxidation of tartronic acid Rosaria Ciriminna and Mario Pagliaro (2004), Oxidation of tartronic acid and dihydroxyacetone to sodium mesoxalate mediated by TEMPO.
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As a consequence of this change the material becomes more brittle, with a reduction in its tensile, impact and elongation strength. Discoloration and loss of surface smoothness accompany photo-oxidation. High temperature and localized stress concentrations are factors that significantly increase the effect of photo- oxidation.
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Two other short-lived xenon compounds with an oxidation state of +8, XeO3F2 and XeO2F4, are accessible by the reaction of xenon tetroxide with xenon hexafluoride. XeO3F2 and XeO2F4 can be detected with mass spectrometry. The perxenates are also compounds where xenon has the +8 oxidation state.
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Rhenium compounds are known for all the oxidation states between −3 and +7 except −2. The oxidation states +7, +6, +4, and +2 are the most common. Rhenium is most available commercially as salts of perrhenate, including sodium and ammonium perrhenates. These are white, water-soluble compounds.
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Hydrogen peroxide is both an oxidizing agent and reducing agent. The oxidation of hydrogen peroxide by sodium hypochlorite yields singlet oxygen. The net reaction of a ferric ion with hydrogen peroxide is a ferrous ion and oxygen. This proceeds via single electron oxidation and hydroxyl radicals.
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Water (H2O) is the most familiar oxygen compound The oxidation state of oxygen is −2 in almost all known compounds of oxygen. The oxidation state −1 is found in a few compounds such as peroxides. Compounds containing oxygen in other oxidation states are very uncommon: − (superoxides), − (ozonides), 0 (elemental, hypofluorous acid), + (dioxygenyl), +1 (dioxygen difluoride), and +2 (oxygen difluoride). Oxygen is reactive and will form oxides with all other elements except the noble gases helium, neon, argon, and krypton.
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This oxidation number is found in sulfates, selenates, tellurates, polonates, and their corresponding acids, such as sulfuric acid. Oxygen is the most electronegative element except for fluorine, and forms compounds with almost all of the chemical elements, including some of the noble gases. It commonly bonds with many metals and metalloids to form oxides, including iron oxide, titanium oxide, and silicon oxide. Oxygen's most common oxidation state is −2, and the oxidation state −1 is also relatively common.
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Redox (reduction-oxidation) reactions include all chemical reactions in which atoms have their oxidation state changed by either gaining electrons (reduction) or losing electrons (oxidation). Substances that have the ability to oxidize other substances are said to be oxidative and are known as oxidizing agents, oxidants or oxidizers. An oxidant removes electrons from another substance. Similarly, substances that have the ability to reduce other substances are said to be reductive and are known as reducing agents, reductants, or reducers.
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In 2003, global production was about 1 million tonnes. Before 1962, ethanol and acetylene were the major sources of acetaldehyde. Since then, ethylene is the dominant feedstock. The main method of production is the oxidation of ethylene by the Wacker process, which involves oxidation of ethylene using a homogeneous palladium/copper system: :2 CH2=CH2 \+ O2 → 2 CH3CHO In the 1970s, the world capacity of the Wacker-Hoechst direct oxidation process exceeded 2 million tonnes annually.
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Despite its importance to environmental contamination, the specific source and processes involved in natural perchlorate production remain poorly understood. Laboratory experiments in conjunction with isotopic studies have implied that perchlorate may be produced on earth by oxidation of chlorine species through pathways involving ozone or its photochemical products. Other studies have suggested that perchlorate can also be created by lightning activated oxidation of chloride aerosols (e.g., chloride in sea salt sprays), and ultraviolet or thermal oxidation of chlorine (e.g.
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Hypofluorous acid, chemical formula HOF, is the only known oxoacid of fluorine and the only known oxoacid which the main atom gains electrons from oxygen to create a negative oxidation state. The oxidation state of the oxygen in hypofluorites is 0. It is also the only hypohalous acid that can be isolated as a solid. HOF is an intermediate in the oxidation of water by fluorine, which produces hydrogen fluoride, oxygen difluoride, hydrogen peroxide, ozone and oxygen.
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This theory has been supported by a series of discoveries from rat livers, human leukocytes, etc. Actually, monitoring a system by applying the isotopical label [18O]-H2O2 shows greater oxidation in cellular RNA than in DNA. Oxidation randomly damages RNAs, and each attack bring problems to the normal cellular metabolism. Although alteration of genetic information on mRNA is relatively rare, oxidation on mRNAs in vitro and in vivo results in low translation efficiency and aberrant protein products.
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Although in soils ammonia oxidation occurs by both AOB and AOA, AOA dominate in both soils and marine environments, suggesting that Thaumarchaeota may be greater contributors to ammonia oxidation in these environments. The second step (oxidation of nitrite into nitrate) is done (mainly) by bacteria of the genus Nitrobacter and Nitrospira. Both steps are producing energy to be coupled to ATP synthesis. Nitrifying organisms are chemoautotrophs, and use carbon dioxide as their carbon source for growth.
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Advanced oxidation processes (AOPs), in a broad sense, are a set of chemical treatment procedures designed to remove organic (and sometimes inorganic) materials in water and wastewater by oxidation through reactions with hydroxyl radicals (·OH). In real-world applications of wastewater treatment, however, this term usually refers more specifically to a subset of such chemical processes that employ ozone (O3), hydrogen peroxide (H2O2) and/or UV light. One such type of process is called in situ chemical oxidation.
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Most thermal oxidation is performed in furnaces, at temperatures between 800 and 1200 °C. A single furnace accepts many wafers at the same time, in a specially designed quartz rack (called a "boat"). Historically, the boat entered the oxidation chamber from the side (this design is called "horizontal"), and held the wafers vertically, beside each other. However, many modern designs hold the wafers horizontally, above and below each other, and load them into the oxidation chamber from below.
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Sodium dithionate is produced by the oxidation of sodium bisulfite by manganese dioxide: :2 NaHSO3 \+ MnO2 → Na2S2O6 \+ MnO + H2O Alternatively, it can be prepared by the oxidation of sodium sulfite by the silver(I) cation: : + 2 Ag + SO → + 2 Ag Another method is via oxidation of sodium thiosulfate with chlorine: :3 Cl2 \+ Na2S2O3·5H2O + 6 NaOH → Na2S2O6 \+ 6 NaCl + 8 H2O And another method to produce sodium dithionate is treating sodium thiosulfate with sodium hypochlorite solution.
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UV is the +5 oxidation state of uranium which is found in the form of [UO2]1+. This species is known as pentavalent uranyl cation and has a low stability due to the disproportionation into tetravalent and hexavalent uranium species. The oxidation states of uranium compounds vary from +2 to +6 (UII \- UVI). Out of all these oxidation states +6 is the most common one and it is found in the form of [UO2]2+ (uranyl dication).
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When compounds in this oxidation state are formed, the outer shell s electrons are lost, yielding a bare zinc ion with the electronic configuration [Ar]3d10. In aqueous solution an octahedral complex, is the predominant species. The volatilization of zinc in combination with zinc chloride at temperatures above 285 °C indicates the formation of , a zinc compound with a +1 oxidation state. No compounds of zinc in oxidation states other than +1 or +2 are known.
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In this genome, the gene neighborhood of a molybdopterin oxidoreductase protein was identified as a place to start looking at candidate iron oxidation pathway genes. In a follow up analysis of a metagenomic sample, Singer et al. (2013) concluded that this molybdopterin oxidoreductase gene cassette was likely involved in Fe oxidation. Comparative analysis of several single cell genomes, however, suggested an alternative conserved gene cassette with several cytochrome c and cytochrome oxidase genes to be involved in Fe oxidation.
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Only strong bases, oxygen above about , and molten metals react with it to form carbides and silicides. The reaction with oxygen forms and , whereby a surface layer of slows down subsequent oxidation (passive oxidation). Temperatures above about and a low partial pressure of oxygen result in so-called active oxidation, in which CO, and gaseous SiO are formed causing rapid loss of SiC. If the SiC matrix is produced other than by CVI, corrosion-resistance is not as good.
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Failing to do this might result in switches remaining electrically "open" when pressed, due to contact oxidation.
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Such SiNWs can be fabricated by thermal oxidation in large quantities to yield nanowires with controllable thickness.
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During physical activity, up to 60% of the heart muscle's energy turnover rate derives from lactate oxidation.
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Hydrogenation of the aldehyde gives isobutanol. Oxidation gives methacrolein or methacrylic acid. Condensation with formaldehyde gives hydroxypivaldehyde.
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Oxidation of methionine residues in tissue proteins can cause them to misfold or otherwise render them dysfunctional.
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TEMPO was discovered by Lebedev and Kazarnowskii in 1960. It is prepared by oxidation of 2,2,6,6-tetramethylpiperidine.
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Although more difficult than reduction, oxidation of fullerene is possible for instance with oxygen and osmium tetraoxide.
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John Wiley & Sons: New York, 2002. and the oxidation of amines to N-oxides with sodium percarbonate.
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Ni(IV) remains a rare oxidation state of nickel and very few compounds are known to date.
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The naturally occurring mineral anglesite, PbSO4, occurs as an oxidation product of primary lead sulfide ore, galena.
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Daniel Swern (January 21, 1916 - December 5, 1982) was an American chemist who discovered the Swern oxidation.
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The reaction of nitrosyl chloride with aromatic alcohols generally yields nitroso compounds and other over-oxidation products.
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Au nanoparticles in different CDCs (TiC-CDC, Mo2C-CDC, B4C-CDC) catalyze the oxidation of carbon monoxide.
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There have also been reports of premature oxidation occurring in wines from Australia, Alsace, Germany, and Bordeaux.
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The p-hydroxylbenzyl alcohol, p-hydroxylbenzaldehye, p-hyrdoxylbenzoate, and benzoate intermediates all are produced from this oxidation and released into the sediments. Similar results were also produced by different studies using other forms of oxidation such as: iron-reducing organisms, Copper/Manganese Oxide catalyst, and nitrate- reducing conditions.
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This gene is a member of the 3-hydroxyacyl-CoA dehydrogenase gene family. The encoded protein functions in the mitochondrial matrix to catalyze the oxidation of straight-chain 3-hydroxyacyl-CoAs as part of the beta-oxidation pathway. Its enzymatic activity is highest with medium-chain-length fatty acids.
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Ascorbic acid (vitamin C) is known to interfere with the oxidation reaction of the blood and glucose pad on common urine test strips. Some urine test strips are protected against the interference with iodate, which eliminates ascorbic acid by oxidation. Some test strips include a test for urinary ascorbate.
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Hence, the main oxidation state of unbiunium in its compounds should be +3, although the closeness of the valence subshells' energy levels may permit higher oxidation states, just like in elements 119 and 120. The standard electrode potential for the Ubu3+/Ubu couple is predicted as −2.1 V.
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Oxidation and impurities in the metal films affect the diffusion reactions by reducing the diffusion rates. Therefore, clean deposition practices and bonding with oxide removal and re-oxidation prevention steps are applied. The oxide layer removal can be realized by various oxide etch chemistry methods. Dry etching processes, i.e.
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Acetaminophen is metabolized in the liver via glucuronide conjugation, sulfate conjugation or oxidation. The CYP450 dependent (CYP1A2, CYP2E1, and CYP3A4) oxidation pathway produces a reactive metabolite that conjugates with glutathione. The glutathione conjugate is then metabolized to cysteine and mercapturic acid conjugates. Hydrocodone is mainly excreted in the urine.
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Chemoautotrophic arsenite oxidizers (CAO) and heterotrophic arsenite oxidizers (HAO) convert As(III) into As(V). CAO combine the oxidation of As(III) with the reduction of oxygen or nitrate. They use obtained energy to fix produce organic carbon from CO2. HAO cannot obtain energy from As(III) oxidation.
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Glucuronolactone is the self-ester (lactone) of glucuronic acid. Direct oxidation of an aldose affects the aldehyde group first. A laboratory synthesis of a uronic acid from an aldose requires protecting the aldehyde and hydroxy groups from oxidation, for example by conversion to cyclic acetals (e. g., acetonides).
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Nickel can enter into metal oxygen clusters with other high oxidation state elements to form polyoxometalates. These may stabilize higher oxidation states of nickel, or show catalytic properties. Nonamolybdonickelate(IV), [NiMo9O32]6− can oxidize aromatic hydrocarbons to alcohols. There is a dark brown heptamolybdonickelate(IV) potassium salt, K2H8NiMo7O28·6H2O.
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Dimethyl sulfide (Me2S) is treated with N-chlorosuccinimide (NCS), resulting in formation of an "active DMSO" species that is used for the activation of the alcohol. Addition of triethylamine to the activated alcohol leads to its oxidation to aldehyde or ketone and generation of dimethyl sulfide. In variance with other alcohol oxidation using "activated DMSO," the reactive oxidizing species is not generated by reaction of DMSO with an electrophile. Rather, it is formed by oxidation of dimethyl sulfide with an oxidant (NCS).
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Electron-donating substituents lower the oxidation potential, whereas electron-withdrawing groups increase the oxidation potential. Thus, 3-methylthiophene polymerizes in acetonitrile and tetrabutylammonium tetrafluoroborate at a potential of about 1.5 V vs. SCE, whereas unsubstituted thiophene requires an additional 0.2 V. Steric hindrance resulting from branching at the α-carbon of a 3-substituted thiophene inhibits polymerization. In terms of mechanism, oxidation of the thiophene monomer produces a radical cation, which then couple with another monomer to produce a radical cation dimer.
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Illustration of a redox reaction Sodium chloride is formed through the redox reaction of sodium metal and chlorine gas Redox reactions can be understood in terms of transfer of electrons from one involved species (reducing agent) to another (oxidizing agent). In this process, the former species is oxidized and the latter is reduced. Though sufficient for many purposes, these descriptions are not precisely correct. Oxidation is better defined as an increase in oxidation state, and reduction as a decrease in oxidation state.
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This layer protects the metal from further oxidation. The thickness and properties of this oxide layer can be enhanced using a process called anodising. A number of alloys, such as aluminium bronzes, exploit this property by including a proportion of aluminium in the alloy to enhance corrosion resistance. The aluminium oxide generated by anodising is typically amorphous, but discharge assisted oxidation processes such as plasma electrolytic oxidation result in a significant proportion of crystalline aluminium oxide in the coating, enhancing its hardness.
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Studies have shown that magmas that produce island arcs are more oxidized than the magmas that are produced at mid-ocean ridges. This relative degree of oxidation has been determined by the iron oxidation state of fluid inclusions in glassy volcanic rocks. It has been determined that this state of oxidation is correlated with the water content of the mantle wedge. Water itself is a poor oxidant and therefore the oxidizing agent must be transported as a dissolved ion in subducting slab.
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Wet air oxidation has also been used to treat a variety of other industrial process waters and wastewaters which include: · Hazardous WasteHeimbuch, J.; Wilhelmi, A. Wet Air Oxidation – A treatment Means for Aqueous Hazardous Waste Streams. Journal of Hazardous Material. 1985, 12, 187-200. · Kinetic Hydrate Inhibitors (KHI) from produced waterKumfer, B.; Clark, M.; Cook, S.; Garza, T.; Jackson, S. “Treatment of Produced Water Containing KHI by Wet Air Oxidation”, International Conference on Gas Hydrates (ICGH), Beijing, China, 28 July- 1 August 2014.
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Fatty acids are preferentially oxidized because of the inactivation of PDH by fatty acid oxidation inhibiting glucose oxidation. This suggests that mitochondrial metabolism may control fuel selection. Cellular respiration is stimulated by fatty acids and this relates to an increase in the mitochondrial NADH to NAD+ ratio, suggesting that energy provision overtakes energy consumption. Switching from glucose to fatty acid oxidation leads to a bigger proportion of electrons being transported to complex 2 rather than complex 1 of the respiratory chain.
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The reaction can be done at room temperature and is quickly complete. Many other functional groups will not be affected by this reaction. center The Dess- Martin oxidation may be preferable to other oxidation reactions as it is very mild, avoids the use of toxic chromium reagents, does not require large excess or co-oxidants, and for its ease of work up. :Chemical drawing of the mechanism of the Dess-Martin oxidation The reaction produces two equivalents of acetic acid.
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Some practical advantages of gold(I) catalysis include: 1) air stability (due to the high oxidation potential of Au(I)), 2) tolerance towards adventitious moisture (due its low oxophilicity), and 3) relatively low toxicity compared to other pi-acids (e.g., Pt(II) and Hg(II)). Chemically, Au(I) complexes typically do not undergo oxidation to higher oxidation states, and Au(I)-alkyls and -vinyls are not susceptible to β hydride elimination. :Typical mechanism for the gold(I)-catalyzed hydrofunctionalization of alkynes and allenes.
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Primary alcohols (R-CHOH) can be oxidized either to aldehydes (R-CHO) or to carboxylic acids (R-COH). The oxidation of secondary alcohols (R1R2CH-OH) normally terminates at the ketone (R1R2C=O) stage. Tertiary alcohols (R1R2R3C-OH) are resistant to oxidation. The direct oxidation of primary alcohols to carboxylic acids normally proceeds via the corresponding aldehyde, which is transformed via an aldehyde hydrate (R-CH(OH)) by reaction with water before it can be further oxidized to the carboxylic acid.
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As the original plant life is burnt, the ash acts to neutralize the acidic soil and makes the area acceptable for food plants. In time, acidity increases and only native plants will grow, forcing the farmer to move on and clear a new area. Soil color in humid areas is related to the level of oxidation that has occurred in the soil, with red soil being the result of iron oxidation, and yellow soil being the result of aluminum oxidation.
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2,2'-Azobis(2-amidinopropane) dihydrochloride (AAPH) is a chemical compound used to study the chemistry of the oxidation of drugs. It is a free radical- generating azo compound. It is gaining prominence as a model oxidant in small molecule and protein therapeutics for its ability to initiate oxidation reactions via both nucleophilic and free radical mechanisms. 2,2′-azobis (2-amidinopropane) dihydrochloride has been used in experiments on linoleic acid subjected to induced oxidation with different combinations of binary mixtures of natural phenolics.
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The metastable oxidation state Cr(V) is achieved through reductive activation. The researchers performed an experiment to study the interaction between DNA with the carcinogenic chromium by using a Cr(V)-Salen complex at the specific oxidation state. The interaction was specific to the guanine nucleotide in the genetic sequence. In order to narrow the interaction between the Cr(V)-Salen complex with the guanine base, the researchers modified the bases to 8-oxo-G so to have site specific oxidation.
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Less than 1 percent of the drug is excreted unchanged; 92 percent of the metabolised drug is excreted within the first 12 hours. The main metabolites are the N-oxide Ro 12-5637 formed via morpholine N-oxidation and lactam derivative Ro 12-8095 formed via morpholine C-oxidation; active metabolites are found only in trace amounts. The unchanged drug (less than 1%) as well as the metabolites are excreted renally (in urine). The main degradation pathway of moclobemide is oxidation.
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The two main approaches to synthesis of N-H, N-alkyl, and N-aryloxaziridines are oxidation of imines with peracids (A) and amination of carbonyls (B). General oxaziridine synthesis Additionally, oxidation of chiral imines and oxidation of imines with chiral peracids may yield enantiopure oxaziridines. Some oxaziridines have the unique property of configurationally stable nitrogen atoms at room temperature due to an inversion barrier of 100 to 130 kJ/mol. Enantiopure oxaziridines where stereochemistry is entirely due to configurationally stable nitrogen are reported.
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The rather restricted chemistry of krypton in the +2 oxidation state parallels that of the neighboring element bromine in the +1 oxidation state; due to the scandide contraction it is difficult to oxidize the 4p elements to their group oxidation states. Until the 1960s no noble gas compounds had been synthesized. However, following the first successful synthesis of xenon compounds in 1962, synthesis of krypton difluoride () was reported in 1963. In the same year, was reported by Grosse, et al.
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In 4-electron dehydrogenases, a single active site catalyses 2 separate oxidation steps: oxidation of the substrate alcohol to an intermediate aldehyde; and oxidation of the aldehyde to the product acid, in this case His. The reaction proceeds via a tightly- or covalently-bound inter-mediate, and requires the presence of 2 NAD molecules. By contrast with most dehydrogenases, the substrate is bound before the NAD coenzyme. A Cys residue has been implicated in the catalytic mechanism of the second oxidative step.
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BBE-like enzymes in plant physiology play a role in primary metabolism catalyzed by members of this family. The oxidation of a variety of alcohol groups supplies a first understanding of the origin of the BBE-like enzyme family, present in reactions like oxidation of mono and polysaccharides. It seems that they are present in a huge percentage of plants. A common reaction of BBE-like enzymes from plants is the oxidation of carbohydrates at the anomeric center to the appropriate lactones.
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The Swern oxidation, which converts primary and secondary alcohols to aldehydes and ketones, respectively, also uses a sulfur-containing compound (DMSO) as the oxidant and proceeds by a similar mechanism. In the Swern oxidation, elimination also occurs via a five-membered ring transition state, but the basic species is a sulfur ylide instead of a negatively charged nitrogen. Several other oxidation reactions also make use of DMSO as the oxidant and pass through a similar transition state (see #See also).
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To reduce the destructive impacts of PFCs on the environment, people have developed many technologies to remove PFCs from aqueous solutions, including adsorption, ion exchange, membrane separation, photochemical oxidation, ultrasonication, bioremediation, plasma oxidation, and other techniques. These technologies require harsh treatment conditions, cause high energy consumption, and cannot be applied in large scale. Electrochemical oxidation (EO) is a promising technique to remove PFCs from contaminated wastewater. It has many advantages, such as relatively lower energy consumption, milder conditions, and higher removal efficiency.
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Slag, a byproduct left over after the smelting process, is used to further absorb impurities such as sulfur or oxides and protect steel from further oxidation. However, it can still be responsible for some oxidation. Some processes, while still able to lead to oxidation, are not relevant to the oxygen content of steel during its manufacture. For example, rust is a red iron oxide that forms when the iron in steel reacts with the oxygen or water in the air.
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A half reaction is either the oxidation or reduction reaction component of a redox reaction. A half reaction is obtained by considering the change in oxidation states of individual substances involved in the redox reaction. Often, the concept of half reactions is used to describe what occurs in an electrochemical cell, such as a Galvanic cell battery. Half reactions can be written to describe both the metal undergoing oxidation (known as the anode) and the metal undergoing reduction (known as the cathode).
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Much later, it was realized that the substance, upon being oxidized, loses electrons, and the meaning was extended to include other reactions in which electrons are lost, regardless of whether oxygen was involved. Oxidation states are typically represented by integers which may be positive, zero, or negative. In some cases, the average oxidation state of an element is a fraction, such as for iron in magnetite (see below) . The highest known oxidation state is reported to be +9 in the tetroxoiridium(IX) cation ().
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A. thiooxidans is obligately aerobic because it uses atmospheric oxygen for the oxidation of sulfur to sulfuric acid.
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If boric acid is used, it has a regulating effect as ester formation occurs, which prevents further oxidation.
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Polythiophenes become electrically conductive upon partial oxidation, i.e. they obtain some of the characteristics typically observed in metals.
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Asymmetric catalytic oxidation is a technique of oxidizing various substrates to give an enantiopure product using a catalyst.
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Maximum valences for the elements are based on the data from list of oxidation states of the elements.
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DHODH binds to its FMN cofactor in conjunction with ubiquinone to catalyze the oxidation of dihydroorotate to orotate.
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Cell 121(7): 965-967. This oxidation step is vital to facilitate further rounds of precursor protein import.
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Both adopt cuboidal structures, but they utilize different oxidation states. They are found in all forms of life.
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The Mn3+ ion itself can degrade lignin by catalyzing alkyl-aryl cleavages and α-carbon oxidation in phenols.
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Finally, again similar to the EETs, EDPs are subject to inactivation by being further metabolized b Beta oxidation.
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This most qualitative process avoids the phenomena of oxidation and premature maceration highly damageable in terms of quality.
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The SOM may play an important yet unconsidered role in carbon sequestration, since some models and experiments with Gammaproteobacteria have suggested that sulfur-dependent carbon fixation in marine sediments could be responsible for almost half of total dark carbon fixation in the oceans. Besides, they may have been critical for the evolution of eukaryotic organisms, given that sulfur metabolism could have driven the formation of the symbiotic associations that sustained them (see below). Although the biological oxidation of reduced sulfur compounds competes with abiotic chemical reactions (e.g. the iron-mediated oxidation of sulfide to iron sulfide (FeS) or pyrite (FeS2)), thermodynamic and kinetic considerations suggest that biological oxidation far exceeds the chemical oxidation of sulfide in most environments.
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When appropriate oxidizing agents are dissolved into the solution, the electro- oxidation process not only leads to organics oxidation at the electrode surface, but it also promotes the formation of other oxidant species within the solution. Such oxidizing chemicals are not bound to the anode surface and can extend the oxidation process to the entire bulk of the system. Chlorides are the most widespread species for the mediated oxidation. This is due to the chlorides being very common in most wastewater effluents and being easily converted into hypochlorite, according to global reaction: Cl- + H2O -> ClO- + 2H+ + 2e- Although hypochlorite is the main product, chlorine and hypochlorous acid are also formed as reactions intermediate.
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In corroboration, primary defects in mitochondrial fatty acid oxidation capacity, as illustrated by LCAD knockout mice, can lead to diacylglycerol accumulation, otherwise known as steatosis, as well as PKCepsilon activation, and hepatic insulin resistance. In animals with very long-chain acyl-CoA dehydrogenase deficiency, LCAD and MCAD work to compensate for the reduced fatty acid oxidation capacity; this compensation is modest, however, and the fatty acid oxidation levels do not return completely to wild type levels. Additionally, LCAD has been shown to have no mechanism that compensates for its deficiency. In the heart, LCAD knockout mice rely more heavily on glucose oxidation, concurrently while there is a large need for replenishment of metabolic intermediates, or analplerosis.
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For transition metals, oxidative reaction results in the decrease in the dn to a configuration with fewer electrons, often 2e fewer. Oxidative addition is favored for metals that are (i) basic and/or (ii) easily oxidized. Metals with a relatively low oxidation state often satisfy one of these requirements, but even high oxidation state metals undergo oxidative addition, as illustrated by the oxidation of Pt(II) with chlorine: :[PtCl4]2− \+ Cl2 → [PtCl6]2− In classical organometallic chemistry, the formal oxidation state of the metal and the electron count of the complex both increase by two. One-electron changes are also possible and in fact some oxidative addition reactions proceed via series of 1e changes.
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Heterogeneous Water Oxidation Water oxidation is one of the half reactions of water splitting: 2H2O → O2 \+ 4H+ \+ 4e− Oxidation (generation of dioxygen) 4H+ \+ 4e− → 2H2Reduction (generation of dihydrogen) 2H2O → 2H2 \+ O2Total Reaction Of the two half reactions, the oxidation step is the most demanding because it requires the coupling of 4 electron and proton transfers and the formation of an oxygen-oxygen bond. This process occurs naturally in plants photosystem II to provide protons and electrons for the photosynthesis process and release oxygen to the atmosphere, as well as in some electrowinning processes. Since hydrogen can be used as an alternative clean burning fuel, there has been a need to split water efficiently. However, there are known materials that can mediate the reduction step efficiently therefore much of the current research is aimed at the oxidation half reaction also known as the Oxygen Evolution Reaction (OER).
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In organic synthesis the hydroboration reaction is taken further to generate other functional groups in the place of the boron group. The hydroboration-oxidation reaction offers a route to alcohols by oxidation of the borane with hydrogen peroxide or to the carbonyl group with the stronger oxidizing agent chromium oxide.
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Studies have shown oxidation-reduction reactions of creosote preservative compounds included compounds that are listed as environmental hazards, such as p-benzoquinone in the oxidation of phenol. Not only are the initial compounds in creosote hazardous to the environment, but the byproducts of the chemical reactions are environmental hazardous as well.
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P. M. Scott, "AN OVERVIEW OF INTERNAL OXIDATION AS A POSSIBLE EXPLANATION OF INTERGRANULAR STRESS CORROSION CRACKING OF ALLOY 600 IN PWRS", Ninth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems—Water Reactors, The Minerals, Metals & Materials Society (TMS), 1999. (pdf) Internal oxidation is distinct from selective leaching.
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Oxidation of peridot does not occur at natural surface temperature and pressure, but begins to occur slowly at 600°C with rates increasing with temperature. The oxidation of the olivine occurs by initial breakdown of the fayalite component, and subsequent reaction with the forsterite component, to give magnetite and orthopyroxene.
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In the area of microelectronics and photovoltaics surface passivation is usually implemented by oxidation to a coating of silicon dioxide. The effect of passivation on the efficiency of solar cells ranges from 3-7%. Passivation is effected by thermal oxidation at 1000 °C. The surface resistivity is high, >100 Ωcm.
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Anisaldehyde is prepared commercially by oxidation of 4-methoxytoluene (p-cresyl methyl ether) using manganese dioxide to convert a methyl group to the aldehyde group. It can also be produced by oxidation of anethole, a related fragrance that is found in some alcoholic beverages, by oxidative cleavage of an alkene.
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In chemistry, compounds of palladium(III) feature the noble metal palladium in the unusual +3 oxidation state (in most of its compounds, palladium has the oxidation state II). Compounds of Pd(III) occur in mononuclear and dinuclear forms. Palladium(III) is most often invoked, not observed in mechanistic organometallic chemistry.
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Zel'dovich mechanism is a chemical mechanism that describes the oxidation of nitrogen and NOx formation, first proposed by the Russian physicist Yakov Borisovich Zel'dovich in 1946.Y.B. Zel'dovich (1946). "The Oxidation of Nitrogen in Combustion Explosions". Acta Physicochimica U.S.S.R. 21: 577–628Zeldovich, Y. A., D. Frank-Kamenetskii, and P. Sadovnikov.
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Often the monoanions are generated by reduction of the neutral hexafluorides. For example, PtF6− arises by reduction of PtF6 by O2. Because of its highly basic nature and its resistance to oxidation, the fluoride ligand stabilizes some metals in otherwise rare high oxidation states, such as hexafluorocuprate(IV), and hexafluoronickelate(IV), .
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The mammalian LD50 is 21.8 mg/kg (rats, oral). Phase I metabolism of tefluthrin proceeds via both oxidation and hydrolysis. Initial targets for oxidation are its methyl groups. Those on the cyclopropane ring and on the tetrafluorobenzene ring are oxidized to alcohol groups which can be further oxidized into carboxylic acids.
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Technetium hexafluoride or technetium(VI) fluoride (TcF6) is a yellow inorganic compound with a low melting point. It was first identified in 1961. In this compound, technetium has an oxidation state of +6, the highest oxidation state found in the technetium halides. The other such compound is technetium(VI) chloride, TcCl6.
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Photosensitization, i.e., photochemical sensitization. Exposing dyed cellulosic material, such as plant-based fibers, to sunlight allows dyes to remove hydrogen from the cellulose, resulting in photoreduction on the cellulosic substrate. Simultaneously, the colorant will undergo oxidation in the presence of the atmospheric oxygen, resulting in photo- oxidation of the colourant.
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Lewis formulae are fine rule-based approximations of chemical reality, as indeed are Allen electronegativities. Still, oxidation states may seem ambiguous when their determination is not straightforward. Rule-based oxidation states feel ambiguous when only experiments can decide. There are also truly dichotomous values to be decided by mere convenience.
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In the mitochondrion, the matrix contains soluble enzymes that catalyze the oxidation of pyruvate and other small organic molecules.
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36 kcal/mol). Oxidation of DMTS by meta-chloroperoxybenzoic acid (mCPBA) gives the corresponding S-monoxide, CH3S(O)SSCH3.
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Succinylacetone is a chemical compound that is formed by the oxidation of glycine and is a precursor of methylglyoxal.
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To properly protect unsaturated fats from oxidation, it is best to keep them cool and in oxygen-free environments.
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Oxidation of Ph2S2 with lead(IV) acetate (Pb(OAc)4) in methanol affords the sulfinite ester PhS(O)OMe.
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Thiosulfate oxidation can occur in the presence or absence of oxygen, although it occurs much slower under anaerobic conditions.
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14260–14261; (Communication) Nitrogen inversion Davies 2006 The system interconverts by oxidation by oxygen and reduction by sodium dithionite.
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Higher potentials per second result in more oxidation/reduction of a species at the surface of the working electrode.
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A Biturox Bitumen Oxidation Unit of 378,000 tonnes per year capacity was successfully commissioned and started- up in 2008.
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A disulfide bond between this cysteine pair increases structural stability and provides resistance to over-oxidation induced enzymatic inactivation.
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Sulfur is tetrahedral in SO2Cl2 and the oxidation state of the sulfur atom is +6, as in sulfuric acid.
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Uranium pentachloride is an inorganic chemical compound composed of uranium in the +5 oxidation state and five chlorine atoms.
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Uranium(IV) iodide, also known as uranium tetraiodide, is an inorganic chemical compound of uranium in oxidation state +4.
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The breaking down the plastic into smaller molecules is known as hydrolysis or oxidation, and this process increases the hydrophilicity of the polymer. Hydrolysis or oxidation is the most important step in the mechanism since it initiates the entire process of plastic biodegradation. Once hydrolysis or oxidation occurs, the microorganisms can act directly on the lower molecular weight products and utilize the carbon in these fragments as a source of energy. Common enzymes involved in microbial plastic biodegradation include lipase, proteinase K, pronase, and hydrogenase, among others.
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Copernicium chemistry is expected to be dominated by the +2 oxidation state, in which it would behave like a post-transition metal similar to mercury, although the relativistic stabilisation of the 7s orbitals means that this oxidation state involves giving up 6d rather than 7s electrons. A concurrent relativistic destabilisation of the 6d orbitals should allow higher oxidation states such as +3 and +4 with electronegative ligands, such as the halogens. A very high standard reduction potential of +2.1 V is expected for the Cn2+/Cn couple.
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A proposed mechanism for the oxidation of an alcohol by Fétizon's reagent involves single electron oxidation of both the alcoholic oxygen and the hydrogen alpha to the alcohol by two atoms of silver(I) within the celite surface. The carbonate ion then proceeds to deprotonate the resulting carbonyl generating bicarbonate which is further protonated by the additionally generated hydrogen cation to cause elimination of water and generation of carbon dioxide.Tojo, Gabriel (2006) "Fétizon's reagent: Silver Carbonate on Celite." Oxidation of Alcohols to Aldehydes and Ketones.
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Unlike oxidation of other amino acids, the oxidation of methionine can be reversed by enzymatic action, specifically by enzymes in the methionine sulfoxide reductase family of enzymes. The three known methionine sulfoxide reductases are MsrA, MsrB, and fRmsr. Oxidation of methionine results in a mixture of the two diastereomers methionine-S-sulfoxide and methionine-R-sulfoxide, which are reduced by MsrA and MsrB, respectively. MsrA can reduce both free and protein-based methionine-S-sulfoxide, whereas MsrB is specific for protein-based methionine-R-sulfoxide.
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Reduced sulfur compounds such as H2S produced by the hydrothermal vents are a major source of energy for sulfur metabolism in microbes. Oxidation of reduced sulfur compounds into forms such as sulfite, thiosulfate, and elemental sulfur is used to produce energy for microbe metabolism such as synthesis of organic compounds from inorganic carbon. The major metabolic pathways used for sulfur oxidation includes the SOX pathway and dissimilatory oxidation. The Sox pathway is a multi enzyme pathway capable of oxidizing sulfide, sulfite, elemental sulfur, and thiosulfate to sulfate.
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The LCAD enzyme catalyzes most of fatty acid beta-oxidation by forming a C2-C3 trans-double bond in the fatty acid. LCAD works on long-chain fatty acids, typically between C12 and C16-acylCoA. LCAD is essential for oxidizing unsaturated fatty acids such as oleic acid, but seems redundant in the oxidation of saturated fatty acids. Fatty acid oxidation has proven to spare glucose in fasting conditions, and is also required for amino acid metabolism, which is essential for the maintenance of adequate glucose production.
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Compounds of zinc are chemical compounds containing the element zinc which is a member of the group 12 of the periodic table. The oxidation state of most compounds is the group oxidation state of +2. Zinc may be classified as a post-transition main group element with zinc(II). Zinc compounds are noteworthy for their nondescript behavior, they are generally colorless (unlike other elements with the oxidation number +2, which are usually white), do not readily engage in redox reactions, and generally adopt symmetrical structures.
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Its chemistry is typical for the late actinides, with a preponderance of the +3 oxidation state but also an accessible +2 oxidation state. Owing to the small amounts of produced fermium and all of its isotopes having relatively short half-lives, there are currently no uses for it outside basic scientific research.
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2,6-Dihydroxypyridine has been investigated in an oxidation method of dyeing hair. The process utilizes 2,6-dihydroxypyridine as a coupling agent, and 2,4,5,6-tetraaminopyrimidine as a primary intermediate. This oxidation method intensifies the color of the dyed hair for several days.Wenke, G.; Wong, Y. Yellow Hair Color Dyeing Composition Having Improved Wear Properties.
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Integrated circuit fabrication technologies, model processes like CVD, thermal oxidation, wet oxidation, doping, etc. use diffusion equations obtained from Fick's law. In certain cases, the solutions are obtained for boundary conditions such as constant source concentration diffusion, limited source concentration, or moving boundary diffusion (where junction depth keeps moving into the substrate).
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It is therefore convenient to keep the pH between 3 and 5 and the temperature below 10 °C. It can also be prepared by oxidation of thiourea with chlorine dioxide.Rábai, G.; Wang, R. T.; Kustin, Kenneth (1993). "Kinetics and mechanism of the oxidation of thiourea by chlorine dioxide" International Journal of Chemical Kinetics.
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The chemistry of mendelevium is typical for the late actinides, with a preponderance of the +3 oxidation state but also an accessible +2 oxidation state. All known isotopes of mendelevium have relatively short half-lives; there are currently no uses for it outside basic scientific research, and only small amounts are produced.
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Potassium ferrate is the chemical compound with the formula K2FeO4. This purple salt is paramagnetic, and is a rare example of an iron(VI) compound. In most of its compounds, iron has the oxidation state +2 or +3 (Fe2+ or Fe3+). Reflecting its high oxidation state, FeO42− is a powerful oxidizing agent.
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Stock nomenclature, still in common use, writes the oxidation number in Roman numerals (... , −II, −I, 0, I, II, ...). So the examples given above would be named iron(II) sulfate and iron(III) sulfate respectively. For simple ions the ionic charge and the oxidation number are identical, but for polyatomic ions they often differ.
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The copper, in a cyanide facilitated oxidation, converts the amine into a colored compound. The Nernst equation explains this process. Another good example of such chemistry is the way in which the saturated calomel reference electrode (SCE) works. The copper, in a cyanide-facilitated oxidation, converts the amine into a colored compound.
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Graphene oxide can be reversibly reduced and oxidized via electrical stimulus. Controlled reduction and oxidation in two-terminal devices containing multilayer graphene oxide films are shown to result in switching between partly reduced graphene oxide and graphene, a process that modifies electronic and optical properties. Oxidation and reduction are related to resistive switching.
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Bekbölet joined the faculty at Boğaziçi University in 1985 as an instructor in the Institute of Environmental Sciences. She was promoted to assistant professor in 1986, associate professor in 1991 and professor in 1997. Bekbölet's researches oxidation techniques, photocatalytic and photolytic reactions, adsorption/bio-oxidation processes in aquatic systems, and drinking water quality.
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Hydroxylammonium chloride is the hydrochloric acid salt of hydroxylamine. Hydroxylamine is a biological intermediate in the nitrification (biological oxidation of ammonia with oxygen into nitrite) and in the anammox (biological oxidation of nitrite and ammonium into dinitrogen gas) which are important in the nitrogen cycle in soil and in wastewater treatment plants.
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PCB mixtures are resistant to acids, bases, oxidation, hydrolysis, and temperature change. They can generate extremely toxic dibenzodioxins and dibenzofurans through partial oxidation. Intentional degradation as a treatment of unwanted PCBs generally requires high heat or catalysis (see Methods of destruction below). PCBs readily penetrate skin, PVC (polyvinyl chloride), and latex (natural rubber).
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In , oxygen is assigned the unusual oxidation state of +1. In most of its other compounds, oxygen has an oxidation state of −2. The structure of dioxygen difluoride resembles that of hydrogen peroxide, , in its large dihedral angle, which approaches 90° and C2 symmetry. This geometry conforms with the predictions of VSEPR theory.
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The methanol oxidation reaction occurs at the anode in direct methanol fuel cells (DMFCs). Platinum is the most promising candidate among pure metals for application in DMFCs. Platinum has the highest activity toward the dissociative adsorption of methanol. However, pure Pt surfaces are poisoned by carbon monoxide, a byproduct of methanol oxidation.
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Several cobalt compounds are oxidation catalysts. Cobalt acetate is used to convert xylene to terephthalic acid, the precursor of the bulk polymer polyethylene terephthalate. Typical catalysts are the cobalt carboxylates (known as cobalt soaps). They are also used in paints, varnishes, and inks as "drying agents" through the oxidation of drying oils.
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Aluminium is rarely found in its +1 oxidation state in nature due to the immense stability of the +3 oxidation state. Rotational transitions of AlF and AlCl have been detected in circumstellar shells near IRC +10216. The presence of AlF suggests that fluorine is produced in helium shell flashes instead of explosive nucleosynthesis.
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Adding pigment light absorbers and photostabilizers (UV absorbers) is one way to minimise photo- oxidation in polymers. Antioxidants are used to inhibit the formation of hydroperoxides in the photo-oxidation process. Dyes and pigments are used in polymer materials to provide color changing properties. These additives can reduce the rate of polymer degradation.
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May 2007. They are effective because the voids can capture particulates as well as support a catalyst that can induce oxidation of the captured particulates. Due to the easy means of deposition of other materials within ceramic foams, these oxidation-inducing catalysts can easily be distributed through the entire foam, increasing effectiveness.
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For many elements (but not all) the highest known oxidation state can be achieved in a fluoride. For some elements this is achieved exclusively in a fluoride, for others exclusively in an oxide; and for still others (elements in certain groups) the highest oxidation states of oxides and fluorides are always equal.
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These radicals are toxic to the melanocytes as it causes auto-oxidation of the cells . Auto-oxidation, in turn, causes oxidative stress to cells, which will impair the natural growth and function of the melanocytes. Rhododenol and raspberry ketone impair the regular proliferation of melanocytes through reactive oxygen species-dependent activation of GADD45 .
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While working for Rupe as assistant, he received his PhD writing a dissertation entitled Die chemische und elektrochemische Oxidation des as. m-Xylidins und seines Mono- und Di-Methylderivates (The Chemical and Electrochemical Oxidation of Asymmetrical m-Xylidene and its Mono- and Di- methyl Derivatives) in 1925. He graduated summa cum laude.
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Nitride coatings might also be used. Whereas there is no consensus on whether zirconium and zirconium alloy have the same oxidation rate, Zircaloys 2 and 4 do behave very similarly in this respect. Oxidation occurs at the same rate in air or in water and proceeds in ambient condition or in high vacuum. A sub-micrometer thin layer of zirconium dioxide is rapidly formed in the surface and stops the further diffusion of oxygen to the bulk and the subsequent oxidation. The dependence of oxidation rate R on temperature and pressure can be expressed asRion A. Causey, Don F. Cowgill, and Bob H. Nilson (2005) Review of the Oxidation Rate of Zirconium Alloys, Engineered Materials Department and Nanoscale Science and Technology Department Sandia National Laboratories :R = 13.9·P1/6·exp(−1.47/kBT) The oxidation rate R is here expressed in gram/(cm2·second); P is the pressure in atmosphere, that is the factor P1/6 = 1 at ambient pressure; the activation energy is 1.47 eV; kB is the Boltzmann constant (8.617 eV/K) and T is the absolute temperature in kelvins. Thus the oxidation rate R is 10−20 g per 1 m2 area per second at 0 °C, 6 g m−2 s−1 at 300 °C, 5.4 mg m−2 s−1 at 700 °C and 300 mg m−2 s−1 at 1000 °C.
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In the analogous selenium system, trifluoroperacetic acid oxidation of selenoethers (R–Se–R) produces selones (R–Se(O)2–R) without the formation of the related selenoxides (R–Se(O)–R) as an isolable product, a reaction which is particularly effective when the R is an aryl group. A general approach to the formation of sulfinyl chlorides (RS(O)Cl) is the reaction of the corresponding thiol with sulfuryl chloride (). In cases where the sulfenyl chloride (RSCl) results instead, a subsequent trifluoroperacetic acid oxidation affords the desired product, as in the case of 2,2,2-trifluoro-1,1-diphenylethanethiol: center The trifluoroperacetic acid oxidation of thiophene illustrates competing pathways for reaction, with both S-oxidation and epoxidation being possible. The major pathway initially forms the sulfoxide, but this chemical promptly undergoes a Diels-Alder-type dimerisation before any further oxidation occurs—neither thiophene-S-oxide or thiophene-S,S-dioxide are found among the products of the reaction.
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The oxidation of pyrite is highly exothermic, allowing the autoclave to operate at this temperature without an external heat source.
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The rate of dehalogenation differs with the type of substrate, metal’s oxidation state, and reducing agents used during the reaction.
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This is not the case for 5hmc as it is glucosylated in the initial step inhibiting its oxidation by TET1.
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Organotin compounds are generally classified according to their oxidation states. Tin(IV) compounds are much more common and more useful.
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Current or developing indoor air purification technologies include filtration, aerosol ultraviolet irradiation, electrostatic precipitation, unipolar ion emission, and photocatalytic oxidation.
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This gene encodes an accessory enzyme which participates in the beta-oxidation and metabolism of unsaturated fatty enoyl- CoA esters.
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Inerting with nitrogen storage tanks of ships and tanks for petroleum products, or for protecting edible oil products from oxidation.
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Both of these oxidation states are kinetically inert. Many analogues of this ion have been prepared using different bridging ligands.
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A photo-toxic reaction pathogenesis is also possible through free radical release in sun screen oxidation by ultra violet radiation.
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Black olives treated with iron(II) gluconate are also depleted in hydroxytyrosol, as iron salts are catalysts for its oxidation.
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However, catalytic partial oxidation of volatile organic compounds has shown that complete conversion can occur in less than 10 milliseconds.
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They can enable the production of astatine in a specific oxidation state and may have greater applicability in experimental radiochemistry.
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Here, fluids react less via chemical exchange of ions, but because of the redox-oxidation potential of the wall rocks.
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Mercury exists in two oxidation states, I and II. Despite claims otherwise, Hg(III) and Hg(IV) compounds remain unknown.
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Older factories typically use air for oxidation whereas newer plants and processes, such as METEOR and Japan Catalytic, favor oxygen.
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For example, triacetone peroxide is the major contaminant found in diisopropyl ether as a result of photochemical oxidation in air.
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Whereas there is no clear threshold of oxidation, it becomes noticeable at macroscopic scales at temperatures of several hundred °C.
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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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Journal of Thermal Analysis and Calorimetry, Vol. 67 (2002) 295~303 These techniques measure the heat flow associated with oxidation.
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Furthermore, research on applied problems of industrial relevance, like oxidation, ozonization, non natural amino acids and catalysis have been pursued.
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This happens in two separate oxidation steps, both requiring molecular oxygen, with H2O2 and H2O produced in the successive processes.
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The print has deteriorated due to oxidation and restorations in 1988 and 1989 were carried out to preserve the print.
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Oxidation, previous to xanthation, increased metal retention in the coal to values comparable with those of a commercial synthetic resin.
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Chromous ions dissolved from the chromium disc could be collected on the gold ring electrode by oxidation to chromic state.
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Proposed early steps in the vanadium-catalyzed oxidation of naphthalene to phthalic anhydride, with V2O5 represented as a molecule vs its true extended structure. Maleic anhydride is produced by the V2O5-catalysed oxidation of butane with air: :C4H10 \+ 4 O2 → C2H2(CO)2O + 8 H2O Maleic anhydride is used for the production of polyester resins and alkyd resins.. Phthalic anhydride is produced similarly by V2O5-catalysed oxidation of ortho-xylene or naphthalene at 350–400 °C. The equation is for the xylene oxidation: :C6H4(CH3)2 \+ 3 O2 → C6H4(CO)2O + 3 H2O Phthalic anhydride is a precursor to plasticisers, used for conferring pliability to polymers. A variety of other industrial compounds are produced similarly, including adipic acid, acrylic acid, oxalic acid, and anthraquinone.
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Photogeochemical reactions may be classified based on thermodynamics and/or the nature of the materials involved. In addition, when ambiguity exists regarding an analogous reaction involving light and living organisms (phototrophy), the term "photochemical" may be used to distinguish a particular abiotic reaction from the corresponding photobiological reaction. For example, "photooxidation of iron(II)" can refer to either a biological process driven by light (phototrophic or photobiological iron oxidation) or a strictly chemical, abiotic process (photochemical iron oxidation). Similarly, an abiotic process that converts water to O2 under the action of light may be designated "photochemical oxidation of water" rather than simply "photooxidation of water", in order to distinguish it from photobiological oxidation of water potentially occurring in the same environment (by algae, for example).
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Ammonia oxidation is important part of the nitrogen cycle, a biogeochemical cycle which cycles nitrogen through its various biological and mineral forms. AOA have been shown to dominate ammonia oxidation in the oceans and thus crenarchaeol, which is generally thought to be produced exclusively by AOA (specifically Thaumarchaeota), has been proposed as a specific biomarker for AOA and ammonia oxidation. Crenarchaeol abundance has been found to track with seasonal blooms of AOA, suggesting that it may be appropriate to use crenarchaeol abundances as a proxy for AOA populations and thus ammonia oxidation more broadly. However the discovery of Thaumarchaeota that are not obligate ammonia- oxidizers complicates this conclusion, as does one study that suggests that crenarchaeol may be produced by Marine Group II Euryarchaeota.
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The only compounds in which gallium has a formal oxidation state of +2 are dimeric compounds, such as , which contain a Ga-Ga bond formed from the unpaired electron on each Ga atom. p. 240 Thus the main difference in oxidation states, between transition elements and other elements is that oxidation states are known in which there is a single atom of the element and one or more unpaired electrons. The maximum oxidation state in the first row transition metals is equal to the number of valence electrons from titanium (+4) up to manganese (+7), but decreases in the later elements. In the second row, the maximum occurs with ruthenium (+8), and in the third row, the maximum occurs with iridium (+9).
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The cell utilizes this in many energetically difficult oxidation reactions such as dehydrogenation of a C-C bond to an alkene. FAD-dependent proteins function in a large variety of metabolic pathways including electron transport, DNA repair, nucleotide biosynthesis, beta-oxidation of fatty acids, amino acid catabolism, as well as synthesis of other cofactors such as CoA, CoQ and heme groups. One well-known reaction is part of the citric acid cycle (also known as the TCA or Krebs cycle); succinate dehydrogenase (complex II in the electron transport chain) requires covalently bound FAD to catalyze the oxidation of succinate to fumarate by coupling it with the reduction of ubiquinone to ubiquinol. The high-energy electrons from this oxidation are stored momentarily by reducing FAD to FADH2.
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When it was realized that some metals form two different binary compounds with the same nonmetal, the two compounds were often distinguished by using the ending -ic for the higher metal oxidation state and the ending -ous for the lower. For example, FeCl3 is ferric chloride and FeCl2 is ferrous chloride. This system is not very satisfactory (although sometimes still used) because different metals have different oxidation states which have to be learned: ferric and ferrous are +3 and +2 respectively, but cupric and cuprous are +2 and +1, and stannic and stannous are +4 and +2. Also there was no allowance for metals with more than two oxidation states, such as vanadium with oxidation states +2, +3, +4 and +5.
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The sulfoxide is a highly polar aprotic solvent and is miscible with water; it is also an excellent ligand. MSM is less reactive than DMSO because the S-atom of the sulfone is already in its highest oxidation state (VI). Indeed, oxidation of the sulfoxide produces the sulfone, both under laboratory conditions and metabolically.
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Ferrocene undergoes a one-electron oxidation at around 0.5 V versus a saturated calomel electrode (SCE). This reversible oxidation has been used as standard in electrochemistry as Fc+/Fc = 0.40 V versus the standard hydrogen electrode.C. E. Housecroft & A. G. Sharpe, Inorganic Chemistry 4th edition, 2012, p. 925. Ferrocenium tetrafluoroborate is a common reagent.
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Gorte's research in solid oxide fuel cells addresses the design of electrodes and applications in hydrocarbon oxidation. In 2000 he published an article in Nature with John Vohs describing the oxidation of methane and higher hydrocarbons with a composite anode of copper and ceria that achieves viable power densities while producing carbon dioxide and water.
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In contrast, molybdenite, MoS2, features isolated sulfide (S2−) centers and the oxidation state of molybdenum is Mo4+. The mineral arsenopyrite has the formula FeAsS. Whereas pyrite has S2 subunits, arsenopyrite has [AsS] units, formally derived from deprotonation of H2AsSH. Analysis of classical oxidation states would recommend the description of arsenopyrite as Fe3+[AsS]3−.
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Another disuplhide bond can form in tTG, between the residues Cys-230 and Cys-370. While this bond does not exist in the enzyme's native state, it appears when the enzyme is inactivated via oxidation. The presence of calcium protects against the formation of both disulfide bonds, thus making the enzyme more resistant to oxidation.
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Maleic anhydride is produced by vapor- phase oxidation of n-butane. The overall process converts the methyl groups to carboxylate and dehydrogenates the backbone. The selectivity of the process reflects the robustness of maleic anhydride, with its conjugated double-bond system. Traditionally maleic anhydride was produced by the oxidation of benzene or other aromatic compounds.
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There are three sets of Indium halides, the trihalides, the monohalides, and several intermediate halides. In the monohalides the oxidation state of indium is +1 and their proper names are indium(I) fluoride, indium(I) chloride, indium(I) bromide and indium(I) iodide. The intermediate halides contain indium with oxidation states, +1, +2 and +3.
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Ethylene can be directly oxidized into ethylene oxide using peroxy acids, for example, peroxybenzoic or meta- chloro-peroxybenzoic acid: : Oxidation of ethylene by peroxy acids Oxidation by peroxy acids is efficient for higher alkenes, but not for ethylene. The above reaction is slow and has low yield, therefore it is not used in the industry.
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The oxidation of secondary alcohols to ketones is an important oxidation reaction in organic chemistry. 500px Where a secondary alcohol is oxidised, it is converted to a ketone. The hydrogen from the hydroxyl group is lost along with the hydrogen bonded to the second carbon. The remaining oxygen then forms double bonds with the carbon.
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The inorganic aminoxyl group is a persistent radical, akin to TEMPO. It has been used in some oxidation reactions, e.g. for oxidation of some anilines and phenols. It can also be used as a model for peroxyl radicals in studies that examine the antioxidant mechanism of action in a wide range of natural products.
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Thermal oxidation can be performed on selected areas of a wafer, and blocked on others. This process, first developed at Philips,J. Appels, E. Kooi, M. M. Paffen, J. J. H. Schatorje, and W. H. C. G. Verkuylen, “Local oxidation of silicon and its application in semiconductor-device technology,” PHILIPS RESEARCH Reports, vol. 25, no.
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While the vast majority of rubredoxins are soluble, there exists a membrane-bound rubredoxin, referred to as rubredoxin A, in oxygenic photoautotrophs. Rubredoxins perform one-electron transfer processes. The central iron atom changes between the +2 and +3 oxidation states. In both oxidation states, the metal remains high spin, which helps to minimize structural changes.
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Malonyl-CoA is a highly regulated molecule in fatty acid synthesis; as such, it inhibits the rate-limiting step in beta-oxidation of fatty acids. Malonyl-CoA inhibits fatty acids from associating with carnitine by regulating the enzyme carnitine acyltransferase, thereby preventing them from entering the mitochondria, where fatty acid oxidation and degradation occur.
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For example, if the manganese in [HMnO4]− has an oxidation state of +6 and nE° = 4, and in MnO2 the oxidation state is +4 and nE° = 0, then the slope Δy/Δx is 4/2 = 2, yielding the standard potential of +2. The stability of any terms can be similarly found by this graph.
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Biochemically, aerobic iron oxidation is a very energetically poor process which therefore requires large amounts of iron to be oxidized by the enzyme rusticyanin to facilitate the formation of proton motive force. Like sulfur oxidation, reverse electron flow must be used to form the NADH used for carbon dioxide fixation via the Calvin cycle.
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Anammox stands for anaerobic ammonia oxidation and the organisms responsible were relatively recently discovered, in the late 1990s. This form of metabolism occurs in members of the Planctomycetes (e.g. Candidatus Brocadia anammoxidans) and involves the coupling of ammonia oxidation to nitrite reduction. As oxygen is not required for this process, these organisms are strict anaerobes.
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Fétizon oxidation is the oxidation of primary and secondary alcohols utilizing the compound silver(I) carbonate absorbed onto the surface of celite also known as Fétizon's reagent first employed by Marcel Fétizon in 1968. It is a mild reagent, suitable for both acid and base sensitive compounds. Its great reactivity with lactols makes the Fétizon oxidation a useful method to obtain lactones from a diol. The reaction is inhibited significantly by polar groups within the reaction system as well as steric hindrance of the α-hydrogen of the alcohol.
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599x599pxMicrobial oxidation of sulfur is the oxidation of sulfur by microorganisms to produce energy. The oxidation of inorganic compounds is the strategy primarily used by chemolithotrophic microorganisms to obtain energy in order to build their structural components, survive, grow and reproduce. Some inorganic forms of reduced sulfur, mainly sulfide (H2S/HS−) and elemental sulfur (S0), can be oxidized by chemolithotrophic sulfur-oxidizing prokaryotes, usually coupled to the reduction of oxygen (O2) or nitrate (NO3−). Most of the sulfur oxidizers are autotrophs that can use reduced sulfur species as electron donors for carbon dioxide (CO2) fixation.
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Experimental data from the anaerobic phototroph Chlorobaculum tepidum indicate that microorganisms enhance sulfide oxidation by three or more orders of magnitude. However, the general contribution of microorganisms to total sulfur oxidation in marine sediments is still unknown. The Alpha-, Gamma- and Epsilonproteobacterial SOM account for average cell abundances of 108 cells/m3 in organic-rich marine sediments. Considering that these organisms have a very narrow range of habitats, as explained below, a major fraction of sulfur oxidation in many marine sediments may be accounted for by these groups.
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The symbiotic SOM provides carbon and, in some cases, bioavailable nitrogen to the host, and gets enhanced access to resources and shelter in return. This lifestyle has evolved independently in sediment-dwelling ciliates, oligochaetes, nematodes, flatworms and bivalves. Recently, a new mechanism for sulfur oxidation was discovered in filamentous bacteria. It is called electrogenic sulfur oxidation (e-SOx), and involves the formation of multicellular bridges that connect the oxidation of sulfide in anoxic sediment layers with the reduction of oxygen or nitrate in oxic surface sediments, generating electric currents over centimeter distances.
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Group 10 metals are white to light grey in color, and possess a high luster, a resistance to tarnish (oxidation) at STP, are highly ductile, and enter into oxidation states of +2 and +4, with +1 being seen in special conditions. The existence of a +3 state is debated, as the state could be an illusory state created by +2 and +4 states. Theory suggests that group 10 metals may produce a +6 oxidation state under precise conditions, but this remains to be proven conclusively in the laboratory other than for platinum.
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Pyrite oxidation is sufficiently exothermic that underground coal mines in high- sulfur coal seams have occasionally had serious problems with spontaneous combustion in the mined-out areas of the mine. The solution is to hermetically seal the mined-out areas to exclude oxygen. In modern coal mines, limestone dust is sprayed onto the exposed coal surfaces to reduce the hazard of dust explosions. This has the secondary benefit of neutralizing the acid released by pyrite oxidation and therefore slowing the oxidation cycle described above, thus reducing the likelihood of spontaneous combustion.
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The charge of the metal center plays a role in the ligand field and the Δ splitting. The higher the oxidation state of the metal, the stronger the ligand field that is created. In the event that there are two metals with the same d electron configuration, the one with the higher oxidation state is more likely to be low spin than the one with the lower oxidation state. For example, Fe2+ and Co3+ are both d6; however, the higher charge of Co3+ creates a stronger ligand field than Fe2+.
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Fermented tea (also known as post-fermented tea or dark tea) is a class of tea that has undergone microbial fermentation, from several months to many years. The exposure of the tea leaves to humidity and oxygen during the process also causes endo-oxidation (derived from the tea-leaf enzymes themselves) and exo- oxidation (which is microbially catalysed). The tea leaves and the liquor made from them become darker with oxidation. Thus, the various kinds of fermented teas produced across China are also referred to as dark tea, not be confused with black tea.
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Metabolic N-oxidation of the diet- derived amino-trimethylamine (TMA) is mediated by flavin-containing monooxygenase and is subject to an inherited FMO3 polymorphism in man resulting in a small subpopulation with reduced TMA N-oxidation capacity resulting in fish odor syndrome Trimethylaminuria. Three forms of the enzyme, FMO1 found in fetal liver, FMO2 found in adult liver, and FMO3 are encoded by genes clustered in the 1q23-q25 region. Flavin-containing monooxygenases are NADPH-dependent flavoenzymes that catalyzes the oxidation of soft nucleophilic heteroatom centers in drugs, pesticides, and xenobiotics.
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The wide applicability of the Saegusa–Ito oxidation is exemplified by its use in several classic syntheses of complex molecules. The synthesis of morphine by Tohru Fukuyama in 2006 is one such example, in which the transformation tolerates the presence of carbamate and ether substituents. Fukuyama Synthesis of Morphine Samuel J. Danishefsky's synthesis of both (+) and (-) peribysin began with a Saegusa–Ito oxidation of the Diels-Alder adduct of carvone and 3-trimethylsilyloxy-1,3-butadiene to yield the enone below. In this case the oxidation tolerated the presence of alkene and carbonyl moieties.
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A secondary organic aerosol (SOA) is a molecule produced via oxidation over several generations of a parent organic molecule. In contrast to primary organic aerosols, which are emitted directly from the biosphere, secondary organic aerosols are either formed via homogeneous nucleation through the successive oxidation of gas-phase organic compounds, or through condensation on pre-existing particles. These gas-phase species exert high vapor pressures, meaning they are volatile and stable in the gas-phase. Upon oxidation, the increased polarity, and thus reduced volatility, of the molecules results in a reduction of vapor pressure.
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It is important to note that carnitine acyltransferase I undergoes allosteric inhibition as a result of malonyl-CoA, an intermediate in fatty acid biosynthesis, in order to prevent futile cycling between beta- oxidation and fatty acid synthesis. The mitochondrial oxidation of fatty acids takes place in three major steps: # β-oxidation occurs to convert fatty acids into 2-carbon acetyl-CoA units. # Acetyl-CoA enters into TCA cycle to yield generate reduced NADH and reduced FADH2. # Reduced cofactors NADH and FADH2 participate in the electron transport chain in the mitochondria to yield ATP.
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Schematic of Recuperative Catalytic Oxidizer Catalytic oxidizer (also known as catalytic incinerator) is another category of oxidation systems that is similar to typical thermal oxidizers, but the catalytic oxidizers use a catalyst to promote the oxidation. Catalytic oxidation occurs through a chemical reaction between the VOC hydrocarbon molecules and a precious-metal catalyst bed that is internal to the oxidizer system. A catalyst is a substance that is used to accelerate the rate of a chemical reaction, allowing the reaction to occur in a normal temperature range between and .
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Voloxidation (for volumetric oxidation) involves heating oxide fuel with oxygen, sometimes with alternating oxidation and reduction, or alternating oxidation by ozone to uranium trioxide with decomposition by heating back to triuranium octoxide. A major purpose is to capture tritium as tritiated water vapor before further processing where it would be difficult to retain the tritium. Other volatile elements leave the fuel and must be recovered, especially iodine, technetium, and carbon-14. Voloxidation also breaks up the fuel or increases its surface area to enhance penetration of reagents in following reprocessing steps.
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Winemakers measure caftaric acid levels as their primary method to estimate the oxidation levels that a wine has undergone. For example, press wines, which undergo a high degree of oxidation, will have little to no caftaric acid. Grape reaction product (2-S glutathionyl caftaric acid) is an oxidation compound produced from caftaric acid and found in wine. Malvidin 3-glucoside alone is not oxidized in the presence of grape polyphenol oxidase (PPO), whereas it is degraded in the presence of a crude grape PPO extract and of caftaric acid, forming anthocyanidin-caftaric acid adducts.
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Electro-oxidation (EO), also known as anodic oxidation, is a technique used for wastewater treatment, mainly for industrial effluents, and is a type of advanced oxidation process (AOP). The most general layout comprises two electrodes, operating as anode and cathode, connected to a power source. When an energy input and sufficient supporting electrolyte are provided to the system, strong oxidizing species are formed, which interact with the contaminants and degrade them. The refractory compounds are thus converted into reaction intermediates and, ultimately, into water and CO2 by complete mineralization.
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Butanone may be produced by oxidation of 2-butanol. The dehydrogenation of 2-butanol using a catalyst is catalyzed by copper, zinc, or bronze: :CH3CH(OH)CH2CH3 → CH3C(O)CH2CH3 \+ H2 This is used to produce approximately 700 million kilograms yearly. Other syntheses that have been examined but not implemented include Wacker oxidation of 2-butene and oxidation of isobutylbenzene, which is analogous to the industrial production of acetone. The cumene process can be modified to produce phenol and a mixture of acetone and butanone instead of only phenol and acetone in the original.
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The lower oxidation state of manganese (Mn2+) is yellow in common glass while the higher oxidation states (Mn3+ or higher) is purple. A combination of the two states will give a pink glass. As the manganese and iron may each be in different states of oxidation, the combination of the two can result in a broad range of attractive colours. Manganese in its fully oxidised state, if not present in too great a mass, will also act as a decolourant of glass if the iron is in its yellow, ferric form.
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The common method for the production of DMT from p-xylene (PX) and methanol consists of a multistep process involving both oxidation and esterification. A mixture of p-xylene (PX) and methyl p-toluate is oxidized with air in the presence of a cobalt and manganese catalysts. The acid mixture resulting from the oxidation is esterified with methanol to produce a mixture of esters. The crude ester mixture is distilled to remove all the heavy boilers and residue produced; the lighter esters are recycled to the oxidation section.
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186x186px The oxidation is usually carried out at ambient conditions, in nearly neutral pH conditions, in dimethylformamide or dichloromethane or their mixture. The choice of solvent or their ratio affects the reaction rate; in particular, higher content of dimethylformamide results in stronger oxidation. The slow oxidation rate for some alcohols can be accelerated by the addition of molecular sieves, organic acids or acetic anhydride or of their combinations. The acceleration by molecular sieves works best when their pore diameter is about 0.3 nm, and it is apparently unrelated to their water absorption capability.
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The method combines the reactions of copper ions with the peptide bonds under alkaline conditions (the Biuret test) with the oxidation of aromatic protein residues. The Lowry method is based on the reaction of Cu+, produced by the oxidation of peptide bonds, with Folin–Ciocalteu reagent (a mixture of phosphotungstic acid and phosphomolybdic acid in the Folin–Ciocalteu reaction). The reaction mechanism is not well understood, but involves reduction of the Folin–Ciocalteu reagent and oxidation of aromatic residues (mainly tryptophan, also tyrosine). Experiments have shown that cysteine is also reactive to the reagent.
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Procyanidin B2 can be converted into procyanidin A2 by radical oxidation using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals under neutral conditions.
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The carnitine-mediated entry process is a rate-limiting factor for fatty acid oxidation and is an important point of regulation.
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J. Physiol. 55, 50. 1922\. On the oxidation processes of the echinoderm egg during fertilization. Proc. Roy. Soc. By 93, 213.
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Oxidation of [Co(II)(EDTA)]2− gives [Co(III)(EDTA)]−, which is so kinetically inert that it can be resolved optically.
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This strain is also capable of coupling the hydrogen oxidation with the reduction of sulfur compounds such as thiosulfate and tetrathionate.
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In addition, the CIDEB null mice also have improved insulin sensitivity and enhanced hepatic fatty acid oxidation and whole body metabolism.
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Regnault 1853, p. 208 It shows reluctance to acquire "the high positive oxidation numbers characteristic of nonmetals".Scott & Kanda 1962, p.
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The ADHFE1 gene encodes hydroxyacid-oxoacid transhydrogenase (EC 1.1.99.24), which is responsible for the oxidation of 4-hydroxybutyrate in mammalian tissues.
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This oxidation typically occurs during periods of extended fasting or illness when caloric intake is reduced, and energy needs are increased.
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PCl3 is a precursor to other phosphorus compounds, undergoing oxidation to phosphorus pentachloride (PCl5), thiophosphoryl chloride (PSCl3), or phosphorus oxychloride (POCl3).
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The different colours are due to the extent of oxidation of iron and manganese. It is often incorrectly described as porphyry.
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It creates volatile compounds when mixed with glucose and amino acids in 90 °C. It is a cofactor in tyrosine oxidation.
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Titanium tetrachloride reacts with hexamethylbenzene to give [(η6-C6Me6)TiCl3]+ salts. Reduced arene complexes include the oxidation states −1, 0, +1.
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The isomer shift is useful for determining oxidation state, valency states, electron shielding and the electron-drawing power of electronegative groups.
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In terms of electron- counting formalism, the sulfur atom has an oxidation state of +4 and a formal charge of +1.
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This process involves the excavation of the contaminated area into large bermed areas where they are treated using chemical oxidation methods.
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The oxidation by chromium trioxide in acetic acid leads to a symmetrically substituted 4-pyridone, decarboxylation yields the 3,5-unsubstituted derivative.
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The carbonyl group attenuation at about 6 micrometres can be detected quite easily, and degree of oxidation of the polymer calculated.
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Steps of the local oxidation process in noncontact mode. I: The tip is scanning the sample in noncontact mode oscillating at a constant amplitude. II:When the voltage pulse is applied a liquid meniscus between tip and sample is induced by the electrical field. This liquid meniscus acts like a nanometer-size electrochemical cell where an oxidation reaction is held.
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The contact angle with water on the PFcMA-coated wafers was 70° smaller following oxidation, while in the case of PVFc the decrease was 30°, and the switching of wettability is reversible. In the PFcMA case, the effect of lengthening the chains and hence introducing more ferrocene groups is significantly larger reductions in the contact angle upon oxidation.
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A. aeolicus is used as a model organism for hyperthermophilic bacterium. Many studies have looked at the Aquifex hydrogenases ability to preform the reversible oxidation of dihydrogen (the oxidation reaction) at extremely high temperatures. The success of the properties within the hydrogenases of Aquifex mark the genus as a possible renewable bio-catalysts for hydrogen based fuel cells.
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Like thallium, moscovium should have a common +1 oxidation state and a less common +3 oxidation state, although their relative stabilities may change depending on the complexing ligands or the degree of hydrolysis. Moscovium(I) oxide (Mc2O) should be quite basic, like that of thallium, while moscovium(III) oxide (Mc2O3) should be amphoteric, like that of bismuth.
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4-Nitrobenzoic acid is prepared by oxidation of 4-nitrotoluene using oxygen or dichromate as oxidants. :Preparation of 4-Nitrobenzoic acid Alternatively, it has been prepared by nitration of polystyrene followed by oxidation of the alkyl substituent. This method proceeds with improved para/ortho selectivity owing to the steric protection of the ortho positions by the polymer backbone.
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Oxidation of senecionine to its respective dehydropyrrolizidine is responsible for its toxic effects. In the toxic pathway, the 2-pyrroline in the core is desaturated via an oxidation reaction to form a pyrrolic ester. This metabolite can still subsequently be eliminated if it is conjugated to glutathione. However, this metabolite is toxic because it can act as an electrophile.
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Voet, D, Voet, J. G., Biochemistry (3rd Edition), John Wiley & Sons, Inc., 2004, pg 1095 GMP is formed by the inosinate oxidation to xanthylate (XMP), and afterwards adds an amino group on carbon 2. Hydrogen acceptor on inosinate oxidation is NAD+. Finally, carbon 2 gains the amino group by spending an ATP molecule (which becomes AMP+2Pi).
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Ammonia monooxygenase (, AMO) is an enzyme, which catalyses the following chemical reaction : ammonia + AH2 \+ O2 \rightleftharpoons NH2OH + A + H2O Ammonia monooxygenase contains copper and possibly nonheme iron. AMO is the first enzyme in ammonia oxidation. Aerobic oxidation of ammonia to hydroxylamine via AMO is an endergonic reaction. So, all aerobic ammonia oxidizing organisms conserve energy by further oxidizing hydroxylamine.
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Although orthophosphate (PO43-), the dominant inorganic P species in nature, is oxidation state (P5+), certain microorganisms can use phosphonate and phosphite (P3+ oxidation state) as a P source by oxidizing it to orthophosphate. Recently, rapid production and release of reduced phosphorus compounds has provided new clues about the role of reduced P as a missing link in oceanic phosphorus.
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The tendency of two species to disproportionate or comproportionate can be determined by examining the Frost diagram of the oxidation states; if a species' value of ΔG/F is lower than the line joining the two oxidation numbers on either side of it, then it is more stable and if in a solution, these two species will undergo comproportionation.
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A low- yield total synthesis of the dimethyl ester of ustalic acid was reported in 2006, starting with phlebiarubrone. The oxidation was achieved with lead tetraacetate. Hayakawa and colleagues reported a more efficient synthesis in 2008, using sesamol as a starting point. This procedure requires eight steps, and uses Suzuki–Miyaura coupling and oxidation of methylene acetal.
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It is fired in a reverberatory furnace at about 1000 °C. Sometimes the reverberatory furnace rotated and thus was called a "revolver". The black-ash product of firing must be lixiviated right away to prevent oxidation of sulfides back to sulfate. In the lixiviation process, the black-ash is completely covered in water, again to prevent oxidation.
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Image:NOSreaction.svg Nitric oxide synthases produce NO by catalysing a five-electron oxidation of a guanidino nitrogen of L-arginine (L-Arg). Oxidation of L-Arg to L-citrulline occurs via two successive monooxygenation reactions producing Nω-hydroxy-L-arginine (NOHLA) as an intermediate. 2 mol of O2 and 1.5 mol of NADPH are consumed per mole of NO formed.
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Nyholm noted that the term 'unusual valence state' had an 'historical, but not chemical significance.' 'The definition of usual oxidation state refers to oxidation states that are stable in environments made up of those chemical species that were common in classical inorganic compounds, e.g. oxides, water and other simple oxygen donors, the halogens, excluding fluorine, and sulphur.
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Industrially, furan is manufactured by the palladium-catalyzed decarbonylation of furfural, or by the copper- catalyzed oxidation of 1,3-butadiene: :450px In the laboratory, furan can be obtained from furfural by oxidation to 2-furoic acid, followed by decarboxylation. It can also be prepared directly by thermal decomposition of pentose-containing materials, and cellulosic solids, especially pine wood.
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In Northern Ireland, there are extensive deposits of lignite which is less energy-dense based on oxidation (combustion) at ordinary combustion temperatures (i.e. for the oxidation of carbon - see fossil fuels). The last deep coal mine in the UK closed on 18 December 2015. Twenty-six open cast mines still remained in operation at the end of 2015.
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Thus, calcium chloride, CaCl2, is named 氯化钙 (literally: 'chloride of calcium'). There is also a Chinese analog of the -ic/-ous nomenclature for higher/lower oxidation states. The lower oxidation state is marked with the character 亚 (yà, 'minor; secondary'). For example FeCl2 and FeCl3 are 氯化亚铁 and 氯化铁, respectively.
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Oxidation of an alcohol to aldehyde with the Collins reagent. As a base, pyridine can be used as the Karl Fischer reagent, but it is usually replaced by alternatives with a more pleasant odor, such as imidazole. Pyridinium chlorochromate, pyridinium dichromate, and the Collins reagent (the complex of chromium(VI) oxide are used for the oxidation of alcohols.
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In chemical industry, selective oxidation of pinene with some catalysts gives many compounds for perfumery, such as artificial odorants. An important oxidation product is verbenone, along with pinene oxide, verbenol, and verbenyl hydroperoxide. Pinene left verbenone right Pinenes are the primary constituents of turpentine. The use of pinene as a biofuel in spark ignition engines has been explored.
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A large number of anionic boron hydrides are known, e.g. [B12H12]2−. The formal oxidation number in boranes is positive, and is based on the assumption that hydrogen is counted as −1 as in active metal hydrides. The mean oxidation number for the borons is then simply the ratio of hydrogen to boron in the molecule.
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Nitrite produced in the first step of autotrophic nitrification is oxidized to nitrate by nitrite oxidoreductase (NXR)(2). It is a membrane-associated iron-sulfur molybdoprotein, and is part of an electron transfer chain which channels electrons from nitrite to molecular oxygen. The molecular mechanism of oxidation nitrite is less described than oxidation ammonium. In new research (e.g.
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Nitrogen cycle Nitrification is the biological oxidation of ammonia to nitrite followed by the oxidation of the nitrite to nitrate. The transformation of ammonia to nitrite is usually the rate limiting step of nitrification. Nitrification is an important step in the nitrogen cycle in soil. Nitrification is an aerobic process performed by small groups of autotrophic bacteria and archaea.
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The Kröhnke synthesis for making pyridines possesses a number of succinct advantages over other methods. Unlike the Hantzsch synthesis,Hantzsch, A. (1881). "Condensationprodukte aus Aldehydammoniak und Ketonartigen Verbindungen". Chemische Berichte 14 (2): 1637 the Kröhnke method does not require oxidation to generate the desired product since the α-pyridinium methyl ketone already possesses the correct oxidation state.
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It can be made by oxidising nickel nitrate in a cold alkaline solution with bromine. A mixed oxidation state hydroxide Ni3O2(OH)4 is made if oxidation happens in a hot alkaline solution. A Ni4+ hydroxide: nickel peroxide hydrate NiO2, can be made by oxidising with alkaline peroxide. It is black, and unstable and oxidises water.
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Effect of UV exposure on polypropylene rope Photo-oxidation is the degradation of a polymer surface in the presence of oxygen or ozone. The effect is facilitated by radiant energy such as UV or artificial light. This process is the most significant factor in weathering of polymers. Photo-oxidation is a chemical change that reduces the polymer's molecular weight.
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In a so-called tandem oxidation- Wittig process the aldehyde is formed in situ by oxidation of the corresponding alcohol. As mentioned above, the Wittig reagent itself is usually derived from a primary alkyl halide. Quaternization of triphenylphosphine with most secondary halides is inefficient. For this reason, Wittig reagents are rarely used to prepare tetrasubstituted alkenes.
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This compound is therefore copper(II) nitrate. In the case of cations with a +4 oxidation state, the only acceptable format for the Roman numeral 4 is IV and not IIII. The Roman numerals in fact show the oxidation number, but in simple ionic compounds (i.e., not metal complexes) this will always equal the ionic charge on the metal.
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However, the oxidation proceeds deeper into the bulk with increasing temperature. The hydrogen is anionic due to the electronegativity difference between Zr and H. When prepared as thin films, the crystal structure can be improved and surface oxidation minimized. Zirconium hydrides are soluble in hydrofluoric acid or alcohol; they react violently with water, acids, oxidizers or halogenated compounds.
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The corresponding acetylenic alcohols are also suitable substrates, although the resulting propargylic aldehydes can be quite reactive. Benzylic and even unactivated alcohols are also good substrates. 1,2-Diols are cleaved by to dialdehydes or diketones. Otherwise, the applications of are numerous, being applicable to many kinds of reactions including amine oxidation, aromatization, oxidative coupling, and thiol oxidation.
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Natural forms of zinc phosphate include minerals hopeite and parahopeite. A somewhat similar mineral is natural hydrous zinc phosphate called tarbuttite, Zn2(PO4)(OH). Both are known from oxidation zones of Zn ore beds and were formed through oxidation of sphalerite by the presence of phosphate-rich solutions. The anhydrous form has not yet been found naturally.
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Many 5-coordinate vanadyl complexes have a trigonal bipyramidal geometry, such as VOCl2(NMe3)2. The coordination chemistry of V5+ is dominated by the relatively stable dioxovanadium coordination complexes which are often formed by aerial oxidation of the vanadium(IV) precursors indicating the stability of the +5 oxidation state and ease of interconversion between the +4 and +5 states.
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After Neil Bartlett's discovery in 1962 that xenon can form chemical compounds, a large number of xenon compounds have been discovered and described. Almost all known xenon compounds contain the electronegative atoms fluorine or oxygen. The chemistry of xenon in each oxidation state is analogous to that of the neighboring element iodine in the immediately lower oxidation state.
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Phosphinous acids are usually organophosphorus compounds with the formula R2POH. They are pyramidal in structure. Phosphorus is in the oxidation state III. Most phosphinous acids rapidly convert to the corresponding phosphine oxide, which are tetrahedral and are assigned oxidation state V. Phosphorous acid OP(OH)2H is an example of an phosphinous acid lacking organic substituents.
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Kornelite (heptahydrate) and quenstedtite (decahydrate) are rarely found. Lausenite (hexa- or pentahydrate) is a doubtful species. All the mentioned natural hydrates are unstable compounds connected with Fe-bearing primary minerals (mainly pyrite and marcasite) oxidation in ore beds. In the solutions of the ore beds oxidation zones the iron(III) sulfate is also an important oxidative agent.
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This is dissimilar to other common acidic oxidation reactions such as the Baeyer-Villiger oxidation, which would remove or alter such groups. Additionally, the Sarett reagent is relatively inert towards double bonds and thioether groups. These groups cannot effectively interact with the chromium of the Sarett reagent, as compared to the chromium in oxidizing complexes used prior to 1953.
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Benzoic acid is produced commercially by partial oxidation of toluene with oxygen. The process is catalyzed by cobalt or manganese naphthenates. The process uses abundant materials, and proceeds in high yield. :toluene oxidation The first industrial process involved the reaction of benzotrichloride (trichloromethyl benzene) with calcium hydroxide in water, using iron or iron salts as catalyst.
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Sobrerol was discovered by Ascanio Sobrero as an oxidation product of terpenes. Later the oxidation and reduction reactions of chiral pinene lead also to several possible isomers of carvone (the corresponding cyclohexyl ketone dehydrated at the isopropyl) and sobrerol, making it possible to determine reaction mechanism and the structural properties of pinene and of other terpenes.
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This is a list of known oxidation states of the chemical elements, excluding nonintegral values. The most common states appear in bold. The table is based on that of Greenwood and Earnshaw, with additions noted. Every element exists in oxidation state 0 when it is the pure non-ionized element in any phase, whether monatomic or polyatomic allotrope.
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It most often affects polyunsaturated fatty acids, because they contain multiple double bonds in between which lie methylene bridges (-CH2-) that possess especially reactive hydrogen atoms. As with any radical reaction, the reaction consists of three major steps: initiation, propagation, and termination. The chemical products of this oxidation are known as lipid peroxides or lipid oxidation products (LOPs).
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NiTiO3 has even been utilized as a catalyst in toluene oxidation. Other applications of nickel(II) titanate have yet to be found.
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Short-chain dehydrogenases/reductases (SDRs), such as DHRS7, catalyze the oxidation/reduction of a wide range of substrates, including retinoids and steroids.
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Alternatively, the Great Oxidation Event might be a consequence of eukaryogenesis and its impact on the export and burial of organic carbon.
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Victor Villiger (1 September 1868 - 10 June 1934) was a Swiss-born German chemist and the discoverer of the Baeyer-Villiger oxidation.
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EU IIIb emission standards are said to be achievable using exhaust gas recirculation and exhaust gas after-treatment by diesel oxidation catalyst.
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A redox reaction is a chemical reaction in which there is a change in oxidation state of atoms participating in the reaction.
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Sodium bromide is the most useful inorganic bromide in industry. It is also used as a catalyst in TEMPO- mediated oxidation reactions.
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Sodium benzoate is produced by the neutralization of benzoic acid, which is itself produced commercially by partial oxidation of toluene with oxygen.
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One review hypothesized that the inconsistency with BCAA administration was the result of ammonia accumulation as a result of increased BCAA oxidation.
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Thymine glycol (5,6-dihydroxy-5,6-dihydrothymine) is one of the principal DNA lesions that can be induced by oxidation and ionizing radiation.
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He researched many topics in physical chemistry, including freezing points, the dielectric constant of ice, osmotic pressures, oxidation potentials, and complex ions.
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One electron oxidation of the octacyanomolybdate(IV) leads to the paramagnetic octacyanomolybdate(V), which is a 17-electron complex used in magnetochemistry.
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Expandable graphite is also used in metallurgy to cover melts and moulds. The material serves here as an oxidation protection and insulator.
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Microbiological oxidation of steroids has been studied using Cunninghamella blakesleeana H-334. C. blakesleeana has been used to transform cortexolone to hydrocortisone.
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Even the different batches from similar oxidation method can have differences in their properties due to variations in purification or quenching processes.
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The following example from the total synthesis of (–)-kumausallene by P.A. Evans and coworkers illustrates typical reaction conditions: The Parikh–Doering oxidation.
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Chlorine is often introduced by adding hydrogen chloride or trichloroethylene to the oxidizing medium. Its presence also increases the rate of oxidation.
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Samples of Na2Te, which are colourless when absolutely pure, generally appear purple or dark gray due to the effects of air oxidation.
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Tellurium trioxide (TeO3) is an inorganic chemical compound of tellurium and oxygen. In this compound, tellurium is in the +6 oxidation state.
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Nonadecanoic acid has found applications in the field of metal lubrication. The compound can be prepared by permanganate oxidation of 1-eicosene.
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Uranium pentaiodide is a hypothetical compound of uranium and iodine. In it, uranium has oxidation state +5. UI5 has never been prepared.
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5-Formyluracil is a heterocyclic organic base. It is produced from the oxidation of the methyl group of thymine. It is mutagenic.
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Sometimes it occurs as the pure metal, and rarer in a state of oxidation as an antimonious acid and as the oxysulphide.
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Therefore, thangkas are chemically and physically altered when exposed to light. The ultraviolet in light hastens fibre and dye degradation through photo- oxidation.
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Thus, Oxidation to galactonate serves as an alternate pathway for metabolizing galactose. This oxidative pathway renders accumulated galactonate less harmful than accumulated galactitol.
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Arsenic pentafluoride is a chemical compound of arsenic and fluorine. It is a toxic, colorless gas. The oxidation state of arsenic is +5.
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A hydrogenosome is a membrane bound, redox active organelle. They produce hydrogen gas from the oxidation of pyruvate, and function in anaerobic environments.
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Wound care products, such as "Flaminal Hydro" make use of an alginate hydrogel containing glucose oxidase and other components as an oxidation agent.
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Oxidation of these iron-bearing minerals causes certain varieties of the marble to turn orange-brown when the stone is exposed to weather.
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1,2-Epoxybutane is an organic compound with the formula CH(O)CHCHCH. It is a chiral epoxide prepared by oxidation of 1-butene.
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Upon treatment with acids, it converts to the corresponding manganese(II) salt and water. Oxidation of manganese(II) oxide gives manganese(III) oxide.
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Furthermore, the usual antioxidants can be added to plant stanol ester products as they are to other oils or fats to minimise oxidation.
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FDCA formation will require development of cost-effective and industrially viable oxidation technology that can operate in concert with the necessary dehydration processes.
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Elevated levels of hydrogen sulfide result which reduce beta-oxidation and thus nutrient production leading to a breakdown of the colonic epithelial barrier.
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The human body will produce fewer molecules than oxygen molecules needed because oxidation of food also needs oxygen to produce water and urea.
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The oxidation of iron from Fe(II) to Fe(III), coupled with a further protonation of nitrogen leads to the release of ammonia.
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In D2 deficient models, shivering is a behavioral adaptation to the cold. However, heat production is much less efficient than uncoupling lipid oxidation.
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Glycosomes function in many processes in the cell. These processes include glycolysis, purine salvage, beta oxidation of fatty acids, and ether lipid synthesis.
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The Lemieux–Johnson oxidation, in which an olefin is converted into two aldehyde or ketone fragments, is named after him and Raymond Lemieux.
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Therefore, it has been used to form single crystals of large cation complexes in high oxidation states without reduction of the metallic complex.
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5b00407 This yellow-orange solid is a salt of the superoxide anion. It is an intermediate in the oxidation of sodium by oxygen.
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Tsutomu Katsuki (September 23, 1946 - October 13, 2014) was an organic chemist who primarily focused on asymmetric oxidation reactions utilizing transition metal catalysts.
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When sulfide is depleted, the sulfur globules are consumed and oxidized to sulfate. However, the pathway of sulfur oxidation is not well- understood.
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For example, thiobenzophenone decomposes upon oxidation to the 1,2,4-trithiolane (Ph2C)2S3, which arises via the cycloaddition of Ph2CSS to its parent Ph2CS.
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5-Hydroxyhydantoin is an oxidation product of 2′-deoxycytidine. If not repaired, it may be processed by DNA polymerases that induce mutagenic processes.
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Microcosmic salt and vanadic acid fuse in the oxidation flame to a dark yellow bead which, upon cooling, loses much of its color.
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Bromfield SM, David DJ Sorption and oxidation of manganous ions and reduction of manganese oxide by cell suspensions of a manganese oxidizing bacterium.
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III:When the voltage pulse is off, the AFM feedbacks withdraw the tip from the sample stretching the liquid meniscus. IV: After the meniscus is broken the tip recovers its original oscillation amplitude and continues the scanning. Currently, local oxidation experiments are performed with an atomic force microscope operated in contact or noncontact mode with additional circuits to apply voltage pulses between tip and sample. The local oxidation process is mediated by the formation of a water meniscus. In order to perform Local Oxidation Nanolithography, the relative humidity in the AFM chamber is kept between 30% and 60%.
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Plasma electrolytic oxidation (PEO), also known as electrolytic plasma oxidation (EPO) or microarc oxidation (MAO), is an electrochemical surface treatment process for generating oxide coatings on metals. It is similar to anodizing, but it employs higher potentials, so that discharges occur and the resulting plasma modifies the structure of the oxide layer. This process can be used to grow thick (tens or hundreds of micrometers), largely crystalline, oxide coatings on metals such as aluminium, magnesium and titanium. Because they can present high hardness and a continuous barrier, these coatings can offer protection against wear, corrosion or heat as well as electrical insulation. SEM.
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The name praseodymium comes from the Greek prasinos (πράσινος), meaning "green", and didymos (δίδυμος), "twin". Like most rare-earth elements, praseodymium most readily forms the +3 oxidation state, which is the only stable state in aqueous solution, although the +4 oxidation state is known in some solid compounds and, uniquely among the lanthanides, the +5 oxidation state is attainable in matrix-isolation conditions. Aqueous praseodymium ions are yellowish-green, and similarly praseodymium results in various shades of yellow-green when incorporated into glasses. Many of praseodymium's industrial uses involve its ability to filter yellow light from light sources.
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The adsorption/bio-oxidation process was applied at the Krefeld plant (800 000 P.E.) in 1985 for the first time. The plant was expanded and modified and currently treats municipal and industrial wastewater of 1 200 000 P.E. Currently adsorption/bio-oxidation process is applied at the municipal treatment plants in Germany, the Netherlands (WWTP Dokhaven (Rotterdam), WWTP Utrecht, WWTP Garmerwolde (Groningen) etc.), Austria (WWTP Salzburg, WWTP Strass etc.), Spain, USA, China etc.Inventarisatie van AB-systemen in NL . www.stowa.nl Adsorption/bio-oxidation process is a part of innovative wastewater treatment concept WaterSchoon, realized in the Netherlands.
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Oxidation will cause the long polymer chains to break up and their molecular weight to decrease. This is a non-linear process and tends to approach a critical level below which the mechanical properties are significantly degraded. Different adhesive systems behave differently in regards to oxidation which means they age differently in an oxidizing environment; therefore, it is crucial to have a method of predicting the oxidation aging of an adhesive that is applicable to the actual service without producing unwanted stress factors. Use of temperature as an acceleration factor for polymers and adhesives may not be appropriate.
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Tea is traditionally classified based on the degree or period of oxidation or fermentation the leaves have undergone: ; Green tea: This tea has undergone the least amount of oxidation. The oxidation process is halted by the quick application of heat after tea picking, either with steam, the method preferred in Japan, or by dry roasting and cooking in hot pans, preferred in Chinese tea processing. Tea leaves may be left to dry as separate leaves or they may be rolled into small pellets to make gunpowder tea. This process is time consuming and is typically done with pekoes of higher quality.
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Pilot Omni Processor for fecal sludge treatment by supercritical oxidation at Duke University, U.S. Scientists at Duke University in the U.S. have developed and are testing a pilot fecal sludge treatment unit that fits in a 20-foot shipping container and treats the fecal matter of roughly 1000 people using a new supercritical water oxidation (SCWO) process.Deshusses, M. (2013). Neighborhood-scale treatment of fecal sludge by supercritical oxidation - Various documents on results from research grant. Duke University, Durham, North Carolina, USA The SCWO technology can covert any type of organic waste (fecal, food waste, paper, plastic, etc.) to energy and clean water.
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Attempted syntheses of perbromates were unsuccessful until 1968, when it was finally obtained by the beta decay of selenium-83 in a selenate salt: : → + β− Subsequently, it was successfully synthesized again by the electrolysis of , although only in low yield. Later, it was obtained by the oxidation of bromate with xenon difluoride. Once perbromates are obtained, perbromic acid can be produced by protonating . One effective method of producing perbromate is by the oxidation of bromate with fluorine under alkaline conditions: : + + 2 → + 2 + This synthesis is much easier to perform on a large scale than the electrolysis route or oxidation by xenon difluoride.
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Suib studied photo-catalytic oxygen evolution from non-potable water by using a bio-inspired molecular water oxidation catalyst. His research group found that under specific conditions, the incorporation of manganese cubane clusters in Nafion membranes along with the illumination with light, led to water oxidation in an aqueous solution of sodium chloride and seawater. In the mid 2010s, Suib studied the viability of photo-catalytic oxidation technology for air purification. His group added to the research conducted by UTRC on the reaction rates of volatile organic compounds and then conducted validation studies on purifier prototypes.
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In addition to being the largest known sink for atmospheric methane, this reaction is one of the most important sources of water vapor in the upper atmosphere. Following the reaction of methane with the hydroxyl radical, two dominant pathways of methane oxidation exist: [1] which leads to a net production of ozone, and [2] which causes no net ozone change. For methane oxidation to take the pathway that leads to net ozone production, nitric oxide (NO) must be available to react with CH3O2·. Otherwise, CH3O2· reacts with the hydroperoxyl radical (HO2·), and the oxidation takes the pathway with no net ozone change.
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The advent of Wacker Process has spurred on many investigations into the utility and applicability of the reactions to more complex terminal olefins. The Tsuji- Wacker Oxidation is the palladium(II)-catalyzed transformation of such olefins into carbonyl compounds. Clement and Selwitz were the first to find that using an aqueous DMF as solvent allowed for the oxidation of 1-dodecene to 2-dodecanone, which addressed the insolubility problem of higher order olefins in water. Fahey noted the use of 3-methylsulfolane in place of DMF as solvent increased the yield of oxidation of 3,3-Dimethylbut-1-ene.
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Aldaric acids are usually synthesized by the oxidation of aldoses with nitric acid. In this reaction it is the open-chain (polyhydroxyaldehyde) form of the sugar that reacts. An aldaric acid is an aldose in which both the hydroxyl function of the terminal carbon and the aldehyde function of the first carbon have been fully oxidized to carboxylic acid functions. (Oxidation of just the aldehyde yields an aldonic acid while oxidation of just the terminal hydroxyl group yields an uronic acid.) Aldaric acids cannot form cyclic hemiacetals like unoxidized sugars, but they can sometimes form lactones.
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Nitrospira are capable of aerobic hydrogen oxidation and nitrite oxidation to obtain electrons, but high concentrations of nitrite have shown to inhibit their growth. The optimal temperature for nitrite oxidation and growth in Nitrospira moscoviensis is 39 °C (can range from 33-44 °C) at a pH range of 7.6-8.0 Despite being commonly classified as obligate chemolithotrophs, some are capable of mixotrophy. For instance, under different environments, Nitrospira can choose to assimilate carbon by carbon fixation or by consuming organic molecules (glycerol, pyruvate, or formate). New studies also show that Nitrospira can use urea as a source of nutrient.
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The mechanism of manganese(III)-mediated radical reactions begins with the single-electron oxidation of a carbonyl compound to an α-oxoalkyl radical. Addition to an olefin then occurs, generating adduct radical 2. The fate of 2 is primarily determined by reaction conditions—in the presence of copper(II) acetate, this intermediate undergoes further oxidation to a carbocation and may eliminate to form β,γ-unsaturated ketone 4. Manganese acetate itself can effect the second oxidation of resonance-stabilized adduct radicals to carbocations 5;Melikyan, G. G.; Vostrowsky, O.; Bauer, W.; Bestmann, H. J.; Khan, M.; Nicholas, K. M. J. Org. Chem.
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Danishefsky synthesis of peribysin Yong Qiang Tu's synthesis of the Alzheimer's disease medication galantamine likewise used this reaction in the presence of an acid- sensitive acetal group. Tu synthesis of galantamine Larry E. Overman's synthesis of laurenyne utilizes a one-pot oxidation with pyridinium chlorochromate followed by a Saegusa oxidation, tolerating the presence of a halogen and a sulfonate. Overman synthesis of laurenyne The synthesis of sambutoxin reported by David Williams uses a novel Saegusa–Ito oxidation involving an unprotected enol moiety. The enone product cyclized in situ to regenerate the enol and form the tetrahydropyran ring.
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Moreover, the formation of quinone and o-quinone methide reactive metabolites were proposed to be formed by metabolic oxidation of the OH group of the chromane ring. Detailed quantum chemical analysis of the metabolic pathways for troglitazone has shown that quinone reactive metabolite is generated by oxidation of the OH group, but o-quinone methide reactive metabolite is formed by the oxidation of the methyl (CH3) groups ortho to the OH group of the chromane ring. This understanding has been recently used in the design of novel troglitazone derivatives with antiproliferative activity in breast cancer cell lines.
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Although the classic substrate for the Criegee oxidation are 1,2-diols, the oxidation can be employed with β-amino alcohols, α-hydroxy carbonyls, and α-keto acids, In the case of β-amino alcohols, a free radical mechanism is proposed. The Crigee oxidation can also be employed with 2,3-epoxy alcohols forms α-acetoxy carbonyls. Because the substrates can be produced with specific stereochemistry, such as by Sharpless epoxidation of allylic alcohols, this process can yield chiral molecules. center Criegee oxidations are commonly used in carbohydrate chemistry to cleave 1,2-glycols and differentiate between different kinds of glycol groups.
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Oxidation of As(III) by dissolved O2 is a particularly slow reaction. For example, Johnson and Pilson (1975) gave half- lives for the oxygenation of As(III) in seawater ranging from several months to a year. In other studies, As(V)/As(III) ratios were stable over periods of days or weeks during water sampling when no particular care was taken to prevent oxidation, again suggesting relatively slow oxidation rates. Cherry found from experimental studies that the As(V)/As(III) ratios were stable in anoxic solutions for up to 3 weeks but that gradual changes occurred over longer timescales.
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Fats are catabolised by hydrolysis to free fatty acids and glycerol. The glycerol enters glycolysis and the fatty acids are broken down by beta oxidation to release acetyl-CoA, which then is fed into the citric acid cycle. Fatty acids release more energy upon oxidation than carbohydrates because carbohydrates contain more oxygen in their structures. Steroids are also broken down by some bacteria in a process similar to beta oxidation, and this breakdown process involves the release of significant amounts of acetyl- CoA, propionyl-CoA, and pyruvate, which can all be used by the cell for energy.
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As T. ferrooxidans can grow aerobically at pH values of 1.6 to 3.5, it obtains its energy for chemolithotrophic growth on soluble ferrous ions. Rusticyanin is involved in the respiratory oxidation of ferrous ions to ferric ions, producing three protons for every ferrous ion oxidized. The mechanism of electron transfer in the respiratory oxidation pathway of Fe2+ in T. ferrooxidans is still unclear despite decades of research in this area. However, the involvement of rusticyanin in shuttling electrons from a cytochrome c2 to another cytochrome c4 during the oxidation of ferrous to ferric ions is experimentally shown.
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Inhibitors of this reaction bind to the active site on AMO and prevent or delay the process. The process of oxidation of ammonia by AMO is regarded with importance due to the fact that other processes require the co-oxidation of NH3 for a supply of reducing equivalents. This is usually supplied by the compound hydroxylamine oxidoreductase (HAO) which catalyzes the reaction: : + → − \+ 5 H+ \+ 4 e− The mechanism of inhibition is complicated by this requirement. Kinetic analysis of the inhibition of NH3 oxidation has shown that the substrates of AMO have shown kinetics ranging from competitive to noncompetitive.
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1,4-Benzoquinone is prepared industrially by oxidation of hydroquinone, which can be obtained by several routes. One route involves oxidation of diisopropylbenzene and the Hock rearrangement. The net reaction can be represented as follows: :C6H4(CHMe2)2 \+ 3 O2 → C6H4O2 \+ 2 OCMe2 \+ H2O The reaction proceeds via the bis(hydroperoxide) and the hydroquinone. Acetone is a coproduct.Gerhard Franz, Roger A. Sheldon "Oxidation" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2000 Another major process involves the direct hydroxylation of phenol by acidic hydrogen peroxide: C6H5OH + H2O2 → C6H4(OH)2 \+ H2O Both hydroquinone and catechol are produced.
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Oxidation of diethylene glycol with concentrated nitric acid was described by A. Wurtz in 1861 Diglycolsäure durch Oxidation von DEG In parallel, W. Heintz reported the synthesis of diglycolic acid from chloroacetic acid by heating with sodium hydroxide solution. Diglycolsäure aus Monochloressigsäure In a version with barium hydroxide solution as an alkaline medium, diglycolic acid is obtained in 68% yield after acidification. The yields of the described reactions are unsatisfactory for use on a technical scale. The single-stage nitric acid process gives even in the presence of an oxidation catalyst (vanadium(V)oxide) yields of only 58-60%.
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In a multi-stage process of nitric acid oxidation at 70 °C and multiple crystallization steps, evaporation of the residues and return of the diethylene glycol-containing mother liquor, product yields of up to 99% (based on diethylene glycol) can be achieved. The oxidation of diethylene glycol with air, oxygen or ozone avoids the use of expensive nitric acid and prevents the inevitable formation of nitrous gases. In the presence of a platinum catalyst, yields of 90% can be obtained by air oxidation. On a bismuth platinum contact catalyst, yields of 95% are to be achieved under optimized reaction conditions.
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Compared to other carbohydrates, isomaltulose ingestion is associated with higher rates of fat oxidation and lower rates of fat storage. Mechanistically this involves a lower blood glucose concentration, which then provides a reduced stimulus to insulin secretion, which in turn allows more fatty acids to be released from adipose tissue for oxidation as an energy source. The lower insulin concentration also decreases carbohydrate oxidation, allowing more fatty acids to be oxidized. A lower insulin concentration also lowers the rate of liver free fatty acid recycling via plasma triglycerides and reduces the storage of triglycerides in adipose tissue.
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The fact that berkelium readily assumes oxidation state +4 in solids, and is relatively stable in this state in liquids greatly assists separation of berkelium away from many other actinides. These are inevitably produced in relatively large amounts during the nuclear synthesis and often favor the +3 state. This fact was not yet known in the initial experiments, which used a more complex separation procedure. Various inorganic oxidation agents can be applied to the solutions to convert it to the +4 state, such as bromates (), bismuthates (), chromates ( and CrO), silver(I) thiolate (), lead(IV) oxide (), ozone (), or photochemical oxidation procedures.
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Vanadium(IV) compounds often exist as vanadyl derivatives, which contain the VO2+ center. Ammonium vanadate(V) (NH4VO3) can be successively reduced with elemental zinc to obtain the different colors of vanadium in these four oxidation states. Lower oxidation states occur in compounds such as V(CO)6, and substituted derivatives. Vanadium pentoxide is a commercially important catalyst for the production of sulfuric acid, a reaction that exploits the ability of vanadium oxides to undergo redox reactions. The vanadium redox battery utilizes all four oxidation states: one electrode uses the +5/+4 couple and the other uses the +3/+2 couple.
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Ytterbium(III) oxide The chemical behavior of ytterbium is similar to that of the rest of the lanthanides. Most ytterbium compounds are found in the +3 oxidation state, and its salts in this oxidation state are nearly colorless. Like europium, samarium, and thulium, the trihalides of ytterbium can be reduced to the dihalides by hydrogen, zinc dust, or by the addition of metallic ytterbium. The +2 oxidation state occurs only in solid compounds and reacts in some ways similarly to the alkaline earth metal compounds; for example, ytterbium(II) oxide (YbO) shows the same structure as calcium oxide (CaO).
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For further reading on Fe oxidation pathways see reference. The phylogenetic distance between the Zetaproteobacteria and the Fe-oxidizing freshwater Betaproteobacteria suggests that Fe oxidation and the produced biominerals are the result of convergent evolution. Comparative genomics has been able to identify several genes that are shared between the two clades, however, suggesting that the trait of Fe oxidation could have been horizontally transferred, possibly virally-mediated. Fe mats associated with the Zetaproteobacteria, in addition to oxidizing Fe have been found to have the genetic potential for denitrification, arsenic detoxification, Calvin- Benson-Bassham (CBB) cycle, and reductive tricarboxylic acid (rTCA) cycles.
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The thallium halides include monohalides, where thallium has oxidation state +1, trihalides in which thallium generally has oxidation state +3, and some intermediate halides containing thallium with mixed +1 and +3 oxidation states. These materials find use in specialized optical settings, such as focusing elements in research spectrophotometers. Compared to the more common zinc selenide-based optics, materials such as thallium bromoiodide enable transmission at longer wavelengths. In the infrared, this allows for measurements as low as 350 cm−1 (28 μm), whereas zinc selenide is opaque by 21.5 μm, and ZnSe optics are generally only usable to 650 cm−1 (15 μm).
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X-ray Crystal structure of the Mn4O5Ca core of the oxygen evolving complex of Photosystem II at a resolution of 1.9 Å. Water oxidation catalysis (WOC) is the acceleration (catalysis) of the conversion of water into oxygen and protons: :2 H2O → 4 H+ \+ 4 e− \+ O2 Many catalysts are effective, both homogeneous catalysts and heterogeneous catalysts. The oxygen evolving complex in photosynthesis is the premier example. There is no interest in generating oxygen by water oxidation since oxygen is readily obtained from air. Instead, interest in water oxidation is motivated by its relevance to water splitting, which would provide "solar hydrogen," i.e.
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Many compounds with luster and electrical conductivity maintain a simple stoichiometric formula; such as the golden TiO, blue-black RuO2 or coppery ReO3, all of obvious oxidation state. Ultimately, however, the assignment of the free metallic electrons to one of the bonded atoms has its limits and leads to unusual oxidation states. Simple examples are the LiPb and Cu3Au ordered alloys, the composition and structure of which are largely determined by atomic size and packing factors. Should oxidation state be needed for redox balancing, it is best set to 0 for all atoms of such an alloy.
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Sodium manganate is the inorganic compound with the formula Na2MnO4. This deep green solid is a rarely encountered analogue of the related salt K2MnO4. Sodium manganate is rare because it cannot be readily prepared from the oxidation of manganese dioxide and sodium hydroxide. Instead this oxidation stops at the level of Na3MnO4, and this Mn(V) salt is unstable in solution.
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The accepted catalytic mechanism, called the “ping-pong mechanism,” consists of four major stages. The first stage is the oxidation of the substrate by the double-redox center. After the hydroxyl group of substrate alcohol occupies the solvent coordination site, the hydroxyl group is deprotonated by Tyr495, followed by the release of Tyr495. This step makes the alcohol more prone to oxidation.
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Products of oxidation of polyacetylene For applications, polyacetylenes suffer from many drawbacks. They are insoluble in solvents, making it essentially impossible to process the material. While both cis and trans-polyacetylene show high thermal stability, exposure to air causes a large decrease in the flexibility and conductivity. When polyacetylene is exposed to air, oxidation of the backbone by O2 occurs.
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Oxidation through immobilized cell technology is 12 times more efficient than natural oxidation is under the same conditions. The key difference between traditional air filtration systems and those that employ immobilized cell technology is that the latter does not employ mesh filters. It requires water, electrical power, and biomass for the bioreactor. The base, inert, elements it produces need to be removed periodically.
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Sulfonium-based oxidations of alcohols to aldehydes summarizes a group of organic reactions that transform a primary alcohol to the corresponding aldehyde (and a secondary alcohol to the corresponding ketone). Selective oxidation of alcohols to aldehydes requires circumventing over-oxidation to the carboxylic acid. One popular approach are methods that proceed through intermediate alkoxysulfonium species (, e.g. compound 6) as detailed here.
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"Redox" is a portmanteau of the words "reduction" and "oxidation". The word oxidation originally implied reaction with oxygen to form an oxide, since dioxygen (O2(g)) was historically the first recognized oxidizing agent. Later, the term was expanded to encompass oxygen-like substances that accomplished parallel chemical reactions. Ultimately, the meaning was generalized to include all processes involving loss of electrons.
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They must first undergo beta oxidation in the mitochondria (mostly of skeletal muscle, cardiac muscle, and liver cells). Fatty acids are transported into the mitochondria as an acyl-carnitine via the action of the enzyme CAT-1. This step controls the metabolic flux of beta oxidation. The resulting acetyl-CoA enters the TCA cycle and undergoes oxidative phosphorylation to produce ATP.
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Pyridinium chlorochromate (PCC) is a yellow-orange salt with the formula [C5H5NH]+[CrO3Cl]−. It is a reagent in organic synthesis used primarily for oxidation of alcohols to form carbonyls. A variety of related compounds are known with similar reactivity. PCC offers the advantage of the selective oxidation of alcohols to aldehydes or ketones, whereas many other reagents are less selective.
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This kind of ligand exerts a very strong ligand field, which lowers the energies of the resultant molecular orbitals so that they are favorably occupied. Typical ligands include olefins, phosphines, and CO. Complexes of π-acids typically feature metal in a low-oxidation state. The relationship between oxidation state and the nature of the ligands is rationalized within the framework of π backbonding.
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The accepted nomenclature for dehydrogenases is "donor dehydrogenase," where the donor is the substrate that can be oxidized. Oxidation-reduction reactions are essential to growth and survival of organisms, as the oxidation of organic molecules produces energy. Energy-producing reactions can drive forward the synthesis of important energy molecules, such as ATP in glycolysis. For this reason, dehydrogenases have pivotal roles in metabolism.
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Pressure Oxidation is a process for extracting gold from refractory ore. The most common refractory ores are pyrite and arsenopyrite, which are sulfide ores that trap the gold within them. Refractory ores require pre-treatment before the gold can be adequately extracted. The pressure oxidation process is used to prepare such ores for conventional gold extraction processes such as cyanidation.
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With bulky alkenes one can prepare species such as [HBR2]2, which are also useful reagents in more specialised applications. Borane dimethylsulfide which is more stable than borane–tetrahydrofuran may also be used. Hydroboration can be coupled with oxidation to give the hydroboration-oxidation reaction. In this reaction, the boryl group in the generated organoborane is substituted with a hydroxyl group.
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Perrhenate, like its conjugate acid perrhenic acid, features rhenium in the oxidation state of +7 with a d0 configuration. Solid perrhenate salts takes on the color of the cation. Typical perrhenate salts are the alkali metal derivatives and ammonium perrhenate. These salts are prepared by oxidation of rhenium compounds with nitric acid followed by neutralization of the resulting perrhenic acid.
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Suib conducted his research on environmental chemistry and green synthesis in the early 2000s. He studied the catalytic degradation of methylene blue by applying green oxidation method having TBHP as the oxidant. The catalysts used in the oxidation method originate from a class of porous manganese oxides and are called octahedral molecular sieves. TBHP, rather than hydrogen peroxide, enhanced the methylene blue composition.
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With oxygen present, the addition of the hydroxyl radical leads the cleavage of the ether link, yielding MCP. The other scheme is MCPA oxidation by positive electron holes h+. The positive holes h+ polarize carboxyl group, CH2-COOH bond is split to produce 4-chloro-2-methylphenylformate. With the presence of oxygen, the positive holes h+ oxidation finally yields MCP as well.
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Endothermic gas is a gas that inhibits or reverses oxidation on the surfaces it is in contact with. This gas is the product of incomplete combustion in a controlled environment. An example is hydrogen gas (H2), nitrogen gas (N2), and carbon monoxide (CO). The hydrogen and carbon monoxide are reducing agents, so they work together to shield surfaces from oxidation.
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Oxidized pyrite cubes. Within the weathering environment chemical oxidation of a variety of metals occurs. The most commonly observed is the oxidation of Fe2+ (iron) and combination with oxygen and water to form Fe3+ hydroxides and oxides such as goethite, limonite, and hematite. This gives the affected rocks a reddish-brown coloration on the surface which crumbles easily and weakens the rock.
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The ccNIR protein uses six electrons and seven hydrogens to reduce nitrite to ammonia. The active site of the enzyme contains an iron in a +2 oxidation state. The oxidation level allows nitrite to bond more strongly than to the +3 state due to increased pi backbonding. This electronic effect transfers electron density into the nitrite antibonding orbital between nitrogen and oxygen.
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Aldehyde oxidase (AO) is a metabolizing enzyme, located in the cytosolic compartment of tissues in many organisms. AO catalyzes the oxidation of aldehydes into carboxylic acid, and in addition, catalyzes the hydroxylation of some heterocycles. It can also catalyze the oxidation of both cytochrome P450 (CYP450) and monoamine oxidase (MAO) intermediate products. AO plays an important role in the metabolism of several drugs.
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The genome of the nitrifying chemilithoautotrophic bacterium from the genus Nitrospira encodes for both ammonia and nitrite oxidation. The genes associated with the growth by ammonia oxidation to nitrate are ammonia monooxygenase and hydroxylamine dehydrogenases genes (e.g. amoA gene and hao cluster). This shows that complete nitrifying Nitrospira serve as cornerstones of the nitrogen-cycling microbial communities found in the environment.
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The bluing reaction is caused by oxidation of gyrocyanin. The identity of the chemical causing bluing upon tissue injury was reported in 1973. The molecule, gyrocyanin, is a highly oxidized bis-phenol-substituted cyclopentenone that develops a blue color when it is oxidized. In contrast, the bluing of other boletes has been attributed to the oxidation of variegatic or xerocomic acid.
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Gold- catalyzed reactions fall into two major categories: heterogeneous catalysis including catalysts by gold nanoparticles (e.g., Au/TiO2) and thiol-monolayer gold surfaces, and catalysts on alumina support, including alumina supported Au/CeO2. These catalysts have been investigated for industrially important processes like the oxidation of alcohols, oxidation of carbon monoxide (CO), and various selective hydrogenation reactions (e.g. butadiene to butene).
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As of 1999, 7000 tonnes of synthetic and 100 tonnes of natural benzaldehyde were produced annually. Liquid phase chlorination and oxidation of toluene are the main routes. Numerous other methods have been developed, such as the partial oxidation of benzyl alcohol, alkali hydrolysis of benzal chloride, and the carbonylation of benzene.Brühne, Friedrich and Wright, Elaine (2002) “Benzaldehyde” in Ullmann's Encyclopedia of Industrial Chemistry.
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The mechanism of oxidation of -CH2C(O)R group by SeO2 has been well investigated. The oxidation of carbonyl alpha methylene positions begins with attack by the enol tautomer at the electrophilic selenium center. Following rearrangement and loss of water, a second equivalent of water attacks the alpha position. Selenic acid is liberated in the final step to give the 1,2-dicarbonyl product.
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Supercritical water oxidation uses supercritical water as a medium in which to oxidize hazardous waste, eliminating production of toxic combustion products that burning can produce. The waste product to be oxidised is dissolved in the supercritical water along with molecular oxygen (or an oxidising agent that gives up oxygen upon decomposition, e.g. hydrogen peroxide) at which point the oxidation reaction occurs.
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DHODA catalyzes the oxidation of dihydroorotate to orotate, which is part of the de novo uridine 5'-monophosphate (UMP) synthesis pathway. This oxidation is mediated by flavin mononucleotide (FMN). Here, β-sheets and extended loops enclose the active site forming a cavity, while also hosting several catalytic residues. The Methylophilus methylotrophus trimethylamine dehydrogenase () TIM barrel is an example of a complete domain insertion.
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For example, in diborane B2H6, the boron oxidation state is +3, but in decaborane B10H14, it is 7/5 or +1.4. In these compounds the oxidation state of boron is often not a whole number. The boron nitrides are notable for the variety of structures that they adopt. They exhibit structures analogous to various allotropes of carbon, including graphite, diamond, and nanotubes.
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In sulfinic acids, sulfur has the +4 oxidation state. They are prone to oxidation to sulphonic acids as well as reduction via sulphenic acids (+2) to thiols. Sulphinic acid derivatives disproportionate in the presence of acid: :2 PhSO2H → PhSO2SOPh + H2O :PhSO2SOPh → PhSO2• + PhSO → PhSO3SPh :PhSO3SPh + PhSO2H → PhSO3H + PhSO2SPh When phenylsulfinic acid reacts with sulfur to give thiosulfinates and thiosulfinic acids.
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Niobium forms oxides in the oxidation states +5 (Nb2O5), +4 (NbO2), +3 (), and the rarer oxidation state, +2 (NbO). Most common is the pentoxide, precursor to almost all niobium compounds and alloys. Niobates are generated by dissolving the pentoxide in basic hydroxide solutions or by melting it in alkali metal oxides. Examples are lithium niobate (LiNbO3) and lanthanum niobate (LaNbO4).
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Sulfites occur naturally in wines to some extent. Sulfites are commonly introduced to arrest fermentation at a desired time, and may also be added to wine as preservatives to prevent spoilage and oxidation at several stages of the winemaking. Sulfur dioxide (SO2) protects wine from not only oxidation, but also from bacteria. Without sulfites, grape juice would quickly turn to vinegar.
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The range of respiratory coefficients for organisms in metabolic balance usually ranges from 1.0 (representing the value expected for pure carbohydrate oxidation) to ~0.7 (the value expected for pure fat oxidation). In general, molecules that are more oxidized (e.g., glucose) require less oxygen to be fully metabolized and, therefore, have higher respiratory quotients. Conversely, molecules that are less oxidized (e.g.
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The synthesis of many organic molecules are facilitated by organometallic complexes. Sigma-bond metathesis is a synthetic method for forming new carbon- carbon sigma bonds. Sigma-bond metathesis is typically used with early transition-metal complexes that are in their highest oxidation state. Using transition-metals that are in their highest oxidation state prevents other reactions from occurring, such as oxidative addition.
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URL accessed on 2 April 2006. which leads to a loss of colour, flavour and aroma - sometimes referred to as flattening. In most cases compounds such as sulfur dioxide or erythorbic acid are added to wine by winemakers, which protect the wine from oxidation and also bind with some of the oxidation products to reduce their organoleptic effect.Goode, Jamie (05/16/05).
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Hence alumina, magnesia and chromia, are, respectively, Al2O3, MgO and Cr2O3. Special types of oxides are peroxide, O22−, and superoxide, O2−. In such species, oxygen is assigned higher oxidation states than oxide. The chemical formulas of the oxides of the chemical elements in their highest oxidation state are predictable and are derived from the number of valence electrons for that element.
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Methohexital binds to a distinct site which is associated with Cl− ionophores at GABAA receptors. This increases the length of time which the Cl− ionopores are open, thus causing an inhibitory effect. Metabolism of methohexital is primarily hepatic via demethylation and oxidation. Side-chain oxidation is the primary means of metabolism involved in the termination of the drug's biological activity.
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Ytterbium hydride is the hydride of ytterbium with the chemical formula YbH2. In this compound, the ytterbium atom has an oxidation state of +2 and the hydrogen atoms have an oxidation state of -1. Its resistivity at room temperature is 107 Ω·cm.洪广言. 现代化学基础丛书 第36卷 稀土化学导论.
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Synthesis for BCAAs occurs in all locations of plants, within the plastids of the cell, as determined by presence of mRNAs which encode for enzymes in the metabolic pathway. BCAAs fill several metabolic and physiologic roles. Metabolically, BCAAs promote protein synthesis and turnover, signaling pathways, and metabolism of glucose. Oxidation of BCAAs may increase fatty acid oxidation and play a role in obesity.
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Hafnium carbide (Hf C) is a chemical compound of hafnium and carbon. With a melting point of about 3900 °C it is one of the most refractory binary compounds known. However, it has a low oxidation resistance, with the oxidation starting at temperatures as low as 430 °C. This compound may be seen on future spacecraft as part of the heat shield.
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The "common" oxidation states of these elements typically differ by two instead of one. For example, compounds of gallium in oxidation states +1 and +3 exist in which there is a single gallium atom. No compound of Ga(II) is known: any such compound would have an unpaired electron and would behave as a free radical and be destroyed rapidly.
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Ferrous oxide is more correctly called iron(II) oxide. In chemistry, the adjective ferrous indicates a compound that contains iron in the +2 oxidation state, possibly as the divalent cation Fe2+. It is opposed to "ferric", which indicates presence of iron in a +3 oxidation state, such as the trivalent cation Fe3+."ferrous" entry in the Merriam-Webster online dictionary.
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In the presence of oxygen it is an irreversible reaction, as dehydrogenation of iproniazid at the active site of the enzyme takes place. This dehydrogenation resembles the first step of amine oxidation. After dehydrogenation iproniazid further reacts with the enzyme. Inhibition of MAOs by iproniazid is competitive and sensitive to changes in pH and temperature, similar to oxidation of the monoamine substrate.
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400x400px The oxidation of diphenylacetylene at room temperature yields benzil, presumably through an oxirene intermediate. 400x400px Peroxymonophosphoric acid is an effective reagent for the hydroxylation of aromatic rings. The conversion of mesitylene to mesitol can be achieved at room temperature in less than four hours. 329x329px The compound can be used as an effective oxidizing agent for the Baeyer-Villiger oxidation.
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File:Combinedeffects.PNG The above figure shows oxidation at the least sterically hindered and electronically/stereo-electronically activated site. The White–Chen catalyst relies on the constructive combination of inherent electronic, steric, and stereoelectronic factors within a substrate to favor one site of oxidation. When these factors combine productively, the reaction proceeds with great predictability and an isolated yields of 50% or greater.
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The mechanism for the second generation is shown below. The mechanism does not follow a traditional oxidative addition-transmetelation-reductive elimination pathway like the first generation. In parallel to studies of Cu(I)-dioxygen reactions, a higher oxidation state, Cu-templated coupling is proposed. Coordination of copper(I) to the thioester undergoes oxidation by air to give a copper (II/III) intermediate.
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Nitrification is the process by which ammonia () is converted to nitrate (). Nitrification is actually the net result of two distinct processes: oxidation of ammonia to nitrite () by nitrosifying bacteria (e.g. Nitrosomonas) and oxidation of nitrite to nitrate by the nitrite-oxidizing bacteria (e.g. Nitrobacter). Both of these processes are extremely energetically poor leading to very slow growth rates for both types of organisms.
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It is α-, β-, and ω-oxidation of fatty acid carbon chains that degrades the acids, with preferred pathway being the β-oxidation in the mitochondria and peroxisomes. Very long chain fatty acids cannot be β-oxidized. The number of carbon atoms in the chains of such acids exceeds 22. Such chains must be shortened before being oxidized by mitochondria.
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The original COR-TEN received the standard designation A242 (COR-TEN A) from the ASTM International standards group. Newer ASTM grades are A588 (COR-TEN B) and A606 for thin sheet. All alloys are in common production and use. The surface oxidation of weathering steel takes six months, but surface treatments can accelerate the oxidation to as little as two hours.
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Fluorine's chemistry is dominated by its strong tendency to gain an electron. It is the most electronegative element and elemental fluorine is a strong oxidant. The removal of an electron from a fluorine atom requires so much energy that no known reagents are known to oxidize fluorine to any positive oxidation state. Therefore, fluorine's only common oxidation state is −1.
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Along with its use as an essential vitamin, niacin is also a precursor to many of commercial compounds including cancer drugs, antibacterial agents, and pesticides. Approximately 10,000,000 kilograms of niacin are produced annually worldwide. Niacin is prepared by hydrolysis of nicotinonitrile, which, as described above, is generated by oxidation of 3-picoline. Oxidation can be effected by air, but ammoxidation is more efficient.
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Copper cavities frequently oxidize, which increases their loss. Silver or gold plating prevents oxidation and reduces electrical losses in cavity walls. Even though gold is not quite as good a conductor as copper, it still prevents oxidation and the resulting deterioration of Q factor over time. However, because of its high cost, it is used only in the most demanding applications.
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The anion can also be obtained by electrolysis of a saturated solution of rubidium carbonate in water. In addition, the peroxodicarbonate anion can be obtained by electrosynthesis on boron doped diamond (BDD) electrodes. The formal oxidation of two carbonate ions takes place at the anode. Due to the high oxidation potential of the peroxodicarbonate anion, a high anodic overpotential is necessary.
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Oxidation of the pyrrolizidine to its respective dehydropyrrolizidine is responsible for the toxic effects. In the toxic pathway, the 2-pyrroline in the core is desaturated via an oxidation reaction to form a pyrrolic ester. This metabolite can still subsequently be eliminated if it is conjugated to glutathione. However, this metabolite is toxic because it can act as an electrophile.
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Less frequently, indium forms compounds in oxidation state +2 and even fractional oxidation states. Usually such materials feature In–In bonding, most notably in the halides In2X4 and [In2X6]2−, and various subchalcogenides such as In4Se3.Greenwood and Earnshaw, p. 287 Several other compounds are known to combine indium(I) and indium(III), such as InI6(InIIICl6)Cl3, InI5(InIIIBr4)2(InIIIBr6), InIInIIIBr4.
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Gold(V) fluoride, AuF5, is the only known example of gold in the +5 oxidation state. It most commonly occurs as the dimer Au2F10.
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Successive catalytic reduction and saponification affords aminoalcohol 4. Oxidation of the sulfide to the sulfoxide with a reagent such as metaperiodate gives sulfinalol (5).
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In glycol cleavage, the C−C bond in a vicinal diol is cleaved with formation of ketone or aldehyde functional groups. See Diol oxidation.
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Many homogeneous catalysts are however not organometallic, illustrated by the use of cobalt salts that catalyze the oxidation of p-xylene to terephthalic acid.
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Phytodegradation is the ability of plants to take up and degrade the contaminants. Contaminants are degraded through internal enzymatic activity and photosynthetic oxidation/reduction.
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TMAO is a product of the oxidation of trimethylamine, a common metabolite in animals. TMAO is biosynthesized from trimethylamine, which is derived from choline.
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Small quantities of elemental chlorine are generated by oxidation of chloride to hypochlorite in neutrophils as part of an immune system response against bacteria.
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N.B. Pilling and R.E. BedworthN.B. Pilling, R. E. Bedworth, "The Oxidation of Metals at High Temperatures". J. Inst. Met 29 (1923), p. 529-591.
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Most natural sinks occur as a result of chemical reactions in the atmosphere as well as oxidation by methane consuming bacteria in Earth's soils.
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When the glass envelope breaks, the bulb implodes, exposing the filament to ambient air. The air then usually destroys the hot filament through oxidation.
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Consequently, anions will tend to move towards the anode where they can undergo oxidation. Historically, the anode has also been known as the zincode.
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Likewise, in the reduction reaction, the closer the equilibrium lies to the ion/atom with the more negative oxidation state the higher the potential.
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Mannose can be formed by the oxidation of mannitol. It can also be formed from glucose in the Lobry-de Bruyn-van Ekenstein transformation.
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Acetone can be produced from the oxidation of ingested isopropanol, or from the spontaneous/enzymatic breakdown of acetoacetate (a ketone body) in ketotic individuals.
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Bismuthate is an ion. Its chemical formula is BiO3−. It has bismuth in its +5 oxidation state. It is a very strong oxidizing agent.
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Tellurium adopts a polymeric structure consisting of zig-zag chains of Te atoms. This gray material resists oxidation by air and is not volatile.
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The ore also allows people to further understand the Global Oxidation Event system, for example, showing the exact atmospheric chemical change during that period.
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H T Tien, S Carbone, and E A Dawidowicz."Formation of "black" lipid membranes by oxidation products of cholesterol." Nature. (1966) 212. 718-719.
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Protoxide of tin takes fire in the flame of oxidation, and burns with flame and some white vapor into tin acid, or stannic acid.
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Of these, only one, C17C3.12, encodes a strong mammalian homolog, a mitochrondrial acyl-CoA dehydrogenase, which functions catabolically in mammals in fatty acid oxidation.
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In addition to these chemically induced oxidation reactions, sunlight can photolyze some diesel-related organics such as carbonyls that contain photo-labile functional groups.
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Protoxide of tin takes fire in the flame of oxidation, and burns with flame and some white vapor into tin acid, or stannic acid.
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Chemical oxidation of the copper ore with ferric (Fe3+) ions formed by the microbial oxidation of ferrous ions (derived from the oxidation of pyrite). Three possible reactions for the oxidation of copper ore are: :Cu2S + 1/2 O2 \+ 2 H+ → CuS + Cu2+ \+ H2O :CuS + 2 O2 → Cu2+ \+ SO42− :CuS + 8 Fe3+ \+ 4 H2O → Cu2+ \+ 8 Fe2+ \+ SO42− \+ 8 H+ The copper metal is then recovered by using Fe0 from steel cans: :Fe0 \+ Cu2+ → Cu0 \+ Fe2+ The temperature inside the leach dump often rises spontaneously as a result of microbial activities. Thus, thermophilic iron-oxidizing chemolithotrophs such as thermophilic Acidithiobacillus species and Leptospirillum and at even higher temperatures the thermoacidophilic archaeon Sulfolobus (Metallosphaera sedula) may become important in the leaching process above 40 °C. Similarly to copper, Acidithiobacillus ferrooxidans can oxidize U4+ to U6+ with O2 as electron acceptor.
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The substance exhibits blasting properties, therefore it is sometimes used as a primary explosive. Silver(I) means silver is in its normal +1 oxidation state.
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A prominent nitroxide is prepared by oxidation of (2,2,6,6-tetramethylpiperidin-1-yl)oxyl, commonly referred to as [TEMPO]+. A less expensive analogue is Bobbitt's salt.
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A key disadvantage of these cells is the use of an acidic electrolyte. This increases the corrosion or oxidation of components exposed to phosphoric acid.
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The drug disulfiram (Antabuse) prevents the oxidation of acetaldehyde to acetic acid. Antabuse is sometimes used as a deterrent for alcoholics wishing to stay sober.
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Murray, M., "Mechanisms of inhibitory and regulatory effects of methylenedioxyphenyl compounds on cytochrome P450-dependent drug oxidation", Curr. Drug Metab. 2000, volume 1, 67-84.
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282 (1990); Vol. 64, p.118 (1986) Article. In the Saegusa–Ito oxidation, certain silyl enol ethers are oxidized to enones with palladium(II) acetate.
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The study of chemolithoautotrophic As(III) oxidizers and the heterotrophic As(V) reducers can help the understanding of the oxidation and/or reduction of arsenic.
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The theoretical maximum value of is 21%, because the efficiency of glucose oxidation is only 42%, and half of the ATP so produced is wasted.
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DEHP hydrolyzes to mono-ethylhexyl phthalate (MEHP) and subsequently to phthalate salts. The released alcohol is susceptible to oxidation to the aldehyde and carboxylic acid.
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In at least one species, the enzyme was stereoselective for the R(-) entantiomer. The long-chain alkane/omega-oxidation pathway, from alkane to carboxylic acid.
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For many of these reactions, including reactions with alkynes and carbon dioxide, germanium is found to retain its oxidation state during the transfer of hydrogen.
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Subsequent oxidation of the hydroquinone gives the quinone.Phillip M. Hudnall "Hydroquinone" in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim. 2005 Wiley- VCH, Weinheim. .
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This compound is commercially available. It may be prepared by oxidation of 1,2-bis(phenylthio)ethane to the sulfoxide, followed by reaction with palladium acetate.
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Oxidation states greater than III are more common for iridium than rhodium. They typically feature strong-field ligands. One often cited example is oxotrimesityliridium(V).
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S. barbata is also a prominent organism in scientific research and has been used to study L-3-glycerophosphate Oxidation and location within the mitochondria .
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Nitrobenzoic acid can be prepared through the oxidation of styrene in boiling nitric acid. The salts and esters of nitrobenzoic acids are known as nitrobenzoates.
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TPOX (thermal partial oxidation) reaction temperatures are dependent on the air-fuel ratio or oxygen-fuel ratio. Typical reaction temperatures are 1200°C and above.
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It is common for samples of iodide-containing compounds to become discolored due to the facile aerobic oxidation of the iodide anion to molecular iodine.
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Optimized conditions for such oxidation are provided along with few new interesting results unique to this reaction, such as the appearance of a novel triacid.
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Triphylite is soluble in hydrochloric and sulfuric acid. Under a blowpipe, it melts to form a dark gray, magnetic ball. Over time, the mineral undergoes alteration by oxidation, increasing the oxidation state of iron from +2 to +3 and allowing the lithium to escape, forming heterosite, FePO4. Triphylite forms a complex solution series with lithiophilite, LiMnPO4, so that natural sources of triphylite usually contain manganese.
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Copiapite is a hydrated iron sulfate mineral with formula: Fe2+Fe3+4(SO4)6(OH)2·20(H2O). Copiapite can also refer to a mineral group, the copiapite group. Copiapite is strictly a secondary mineral forming from the weathering or oxidation of iron sulfide minerals or sulfide-rich coal. Its most common occurrence is as the end member mineral from the rapid oxidation of pyrite.
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This two-electron oxidation is achieved by the double-redox site: the copper(II) metal center and the free radical, each capable of accepting one electron from the substrate. This double-redox center has three accessible oxidation levels. In the catalytic cycle of galactose oxidase, the enzyme shuttles between the fully oxidized form and the fully reduced form. The semi-oxidized form is the inactive form.
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The auxin indole-3-acetic acid (IAA) regulates concentration of GA1 in elongating internodes in peas. Removal of IAA by removal of the apical bud, the auxin source, reduces the concentration of GA1, and reintroduction of IAA reverses these effects to increase the concentration of GA1. This phenomenon has also been observed in tobacco plants. Auxin increases GA 3-oxidation and decreases GA 2-oxidation in barley.
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Adsorption/bio-oxidation process was invented in the mid-1970s by the professor of the RWTH Aachen University Botho Böhnke. It was based on the finding, made by the German engineer Karl Imhoff in the 50th. Imhoff stated that the treatment efficiency of 60-80 percent could be achieved in highly loaded activated sludge basins. In 1977 Böhnke published his first article on adsorption/bio-oxidation process.
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390 It has a close-packed crystalline structure (BCN 6+6) but an abnormally large interatomic distance that has been attributed to partial ionisation of the thallium atoms.Wells 1985, p. 1279–80 Although compounds in the +1 (mostly ionic) oxidation state are the more numerous, thallium has an appreciable chemistry in the +3 (largely covalent) oxidation state, as seen in its chalcogenides and trihalides.Howe 1968a, p.
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Penneman, pp. 25–26 The +6 oxidation state has only been reported once in solution in 1978, as the curyl ion (): this was prepared from the beta decay of americium-242 in the americium(V) ion . Failure to obtain Cm(VI) from oxidation of Cm(III) and Cm(IV) may be due to the high Cm4+/Cm3+ ionization potential and the instability of Cm(V).
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Uncouplers of oxidative phosphorylation are specifically acting toxicants. Oxidative phosphorylation is a coupling reaction in which ATP is synthesized from phosphate groups using energy obtained from the oxidation-reduction reactions in the mitochondrial electron transport chain. ATP production is very important because it is essentially the energy currency in biological systems. Under normal circumstances, oxidation-reduction reactions in the mitochondrial electron transport chain produce energy.
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Wendell Mitchell Latimer (April 22, 1893 - July 6, 1955) was a American chemist notable for his description of oxidation states in his book "The Oxidation States of the Elements and Their Potentials in Aqueous Solution" (ASIN B000GRXLSA, first published 1938). He received his Ph.D from the University of California, Berkeley for the work with George Ernest Gibson. He earned many awards and honors for his scientific work.
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Selenium dioxide is useful in organic oxidation. Specifically, SeO2 will convert an allylic methylene group into the corresponding alcohol. A number of other reagents bring about this reaction. Scheme 1. Selenium dioxide oxidation In terms of reaction mechanism, SeO2 and the allylic substrate react via pericyclic process beginning with an ene reaction that activates the C−H bond. The second step is a [2,3] sigmatropic reaction.
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Integrasone (1) is then formed in a single step by oxidation of the primary hydroxyl groups and concerted electron cyclization to form the ring, using sodium chlorite catalyzed by TEMPO and bleach.Zhao, M.; Li, J.; Mano, E.; Song, Z,; Tschaen, D.M.; Grabowski, E.J.J.; Reider, P.J. Oxidation of Primary Alcohols to Carboxylic Acids with Sodium Chlorite Catalyzed by TEMPO and Bleach. J. Org. Chem. 1999, 64, 2564-2566.
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The phosphine reagents slowly undergo air oxidation in living systems. Additionally, it is likely that they are metabolized in vitro by cytochrome P450 enzymes. The kinetics of the reactions are slow with second order rate constants around 0.0020 M−1•s−1. Attempts to increase nucleophilic attack rates by adding electron-donating groups to the phosphines improved kinetics, but also increased the rate of air oxidation.
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Fe–Ni metal clusters are crucial for energy production in many bacteria. A primary source of energy in bacteria is the oxidation and reduction of H2 which is performed by hydrogenase enzymes. These enzymes are able to create a charge gradient across the cell membrane which serves as an energy store. In aerobic environments, the oxidation and reduction of oxygen is the primary energy source.
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An oxidase is an enzyme that catalyzes an oxidation-reduction reaction, especially one involving dioxygen (O2) as the electron acceptor. In reactions involving donation of a hydrogen atom, oxygen is reduced to water (H2O) or hydrogen peroxide (H2O2). Some oxidation reactions, such as those involving monoamine oxidase or xanthine oxidase, typically do not involve free molecular oxygen. The oxidases are a subclass of the oxidoreductases.
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In adsorbed form it is - as opposed to the gas phase - protected from photo-oxidation, i.e. direct photolysis as well as oxidation by OH radicals or ozone. POPs have low solubility in water but are easily captured by solid particles, and are soluble in organic fluids (oils, fats, and liquid fuels). POPs are not easily degraded in the environment due to their stability and low decomposition rates.
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One predicted oxidation state of unbiquadium is +6, which would exist in the halides UbqX6 (X = a halogen), analogous to the known +6 oxidation state in uranium. Like the other early superactinides, the binding energies of unbiquadium's valence electrons are predicted to be small enough that all six should easily participate in chemical reactions. The predicted electron configuration of the Ubq5+ ion is [Og] 6f1.
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One mechanism involves successive oxidations of OEC by hydrogen abstraction. The group tested the viability of this mechanism via use of thermodynamic calculations and studies of their mock system to find that this is indeed a possible mechanism. This dimeric system was also found to exist with variety of different manganese oxidation states. These oxidation states have also been shown to exist in catalase.
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The complex consists of two pentammineruthenium units linked to the nitrogen atoms in a bridging pyrazine ligand, which completes the octahedral coordination sphere of each metal. The important feature of the compound is that the two metals have apparent fractional oxidation states of +2.5. Normally metal ions, like most ions, have integral oxidation states. For example, ruthenium ammine complexes are typically +2 or +3.
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Comproportionation or synproportionation is a chemical reaction where two reactants, each containing the same element but with a different oxidation number, form a product in which the elements involved reach the same oxidation number. It is opposite to disproportionation.Shriver, D. F.; Atkins, P. W.; Overton, T. L.; Rourke, J. P.; Weller, M. T.; Armstrong, F. A. “Inorganic Chemistry” W. H. Freeman, New York, 2006. .
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Pathways available to the adduct radical include further oxidation to a carbocation (and subsequent β-elimination or trapping with a nucleophile) and hydrogen abstraction to generate a saturated carbonyl compound containing a new carbon-carbon bond. Copper(II) acetate is sometimes needed to facilitate the oxidation of adduct radicals to carbocations.Vinogradov, M. G.; Il'ina, G.; Nikishin, G. I. J. Org. Chem. USSR 1974, 10, 1167.
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The reduction-oxidation sensitive green fluorescent protein (roGFP) is a redox sensitive biosensor. Two cysteines were introduced into the beta barrel structure of the GFP. The oxidation state (reduced dithiol or the oxidized disulfide) of the engineered thiols determines the fluorescence properties of the sensor. Originally, different roGFP versions were presented to allow the in vivo imaging of reducing compartments such as the cytosol (roGFP2).
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The oxidation generates water that can be removed by adding molecular sieves. TPAP is expensive, but it can be used in catalytic amounts. The catalytic cycle is maintained by adding a stoichiometric amount of a co-oxidant such as N-methylmorpholine N-oxide or molecular oxygen. Oxidation of alcohol to aldehyde with TPAP (0.06 eq.) and N-methylmorpholine N-oxide (1.7 eq.) with molecular sieves in dichloromethane.
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The LCAD enzyme catalyzes most of fatty acid beta-oxidation by forming a C2-C3 trans-double bond in the fatty acid. MCAD works on long-chain fatty acids, typically between C4 and C12-acylCoA. Fatty acid oxidation has proven to spare glucose in fasting conditions, and is also required for amino acid metabolism, which is essential for the maintenance of adequate glucose production.
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In 1973, Toyota adopted the GM (MS-7176) with GM Dexron-II(C). This upgraded fluid had new oxidation and rust inhibitors to replace the previous sperm whale oil additive. The fluid also had better oxidation resistance characteristics which resulted in longer fluid life. Toyota became a licensed reseller of the GM Dexron-II(C) fluid; it was marketed under the Toyota brand name.
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Her work was supported by the National Science Foundation. She looked at the oxidation of arsenic in the Los Angeles Aqueduct, in particular at Hot Creek. Hot Creek is a geothermal area, where arsenic occurs at high concentrations as it degases from magma. The oxidation state of arsenic impacts its toxicity and mobility, as well as how easily it can be removed with treatment.
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The presence of cable bacteria can lead to a decrease in methane emissions from saturated soils. The transfer of electrons through cable bacteria allows the sulfate reduction that occurs in inundated soils to be balanced by sulfate oxidation. Oxidation is possible because of the release of electrons through the cable bacteria filaments. Through this balance, sulfate remains readily available for sulfate reducing bacteria, which out compete methanogens.
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After the fabric is removed from the dye solution, it is allowed to stand in air whereupon the dye is regenerated by oxidation. The regenerated parent dye is insoluble in water. Oxidation can also be effected in air or by hydrogen peroxide or sodium bromate in a mildly acidic solution. The low water solubility is the basis of the good wash-fastness of these dyed fabrics.
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MoTe2 gradually oxidises in air forming molybdenum dioxide (MoO2). At elevated temperatures MoTe2 oxidation produces Te2MoO7 and TeMo5O16. Other oxidation products include molybdenum trioxide, tellurium, and tellurium dioxide. Flakes of molybdenum ditelluride that contain many defects have lower luminescence, and absorb oxygen from the air, losing their luminescence. When heated to high temperatures, tellurium evaporates from molybdenum ditelluride, producing the tellurium deficient forms and then Mo2Te3.
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This process consumes very large amounts of energy and values over 30 MWh/tonne are not uncommon. To address this problem, sometimes enzymatic/mechanical pre-treatments and introduction of charged groups for example through carboxymethylation or TEMPO-mediated oxidation are used. These pre-treatments can decrease energy consumption below 1 MWh/tonne. "Nitro- oxidation" has been developed to prepare carboxycellulose nanofibers directly from raw plant biomass.
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For example, the hydroxyl is a powerful, non-selective oxidant. Oxidation of an organic compound by Fenton's reagent is rapid and exothermic and results in the oxidation of contaminants to primarily carbon dioxide and water. Reaction () was suggested by Haber and Weiss in the 1930s as part of what would become the Haber–Weiss reaction. Iron(II) sulfate is typically used as the iron catalyst.
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A surprising number of intermediate chlorides and bromides are known, but only one iodide, and no difluoride. Rather than the apparent oxidation state of +2, these compounds contain indium in the +1 and +3 oxidation states. Thus the diiodide is described as InIInIIIX4. It was some time later that the existence of compounds containing the anion In2 were confirmed which contains an indium- indium bond.
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Phenolic compound Callus can brown and die during culture, mainly due to oxidation of phenolic compounds. In Jatropha curcas callus cells, small organized callus cells became disorganized and varied in size after browning occurred. Browning has also been associated with oxidation and phenolic compounds in both explant tissues and explant secretions. In rice, presumably, a condition which is favorable for scutellar callus induction induces necrosis too.
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Cyanobacteria species Cylindrospermum sp. under magnification Cloud's original hypothesis was that ferrous iron was oxidized in a straightforward manner by molecular oxygen present in the water: : The oxygen comes from the photosynthetic activities of cyanobacteria. Oxidation of ferrous iron may have been hastened by aerobic iron-oxidizing bacteria, which can increase rates of oxidation by a factor of 50 under conditions of low oxygen.
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Structure of the trimeric hydrolysis product of beryllium Beryllium hydrolysis as a function of pH. Water molecules attached to Be are omitted in this diagram A beryllium atom has the electronic configuration [He] 2s2. The predominant oxidation state of beryllium is +2; the beryllium atom has lost both of its valence electrons. Lower oxidation states have been found in, for example, bis(carbene) compounds.
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The sign of the oxidation state (positive/negative) actually corresponds to the value of each ion's electronic charge. The attraction of the differently charged sodium and chlorine ions is the reason they then form an ionic bond. The loss of electrons from an atom or molecule is called oxidation, and the gain of electrons is reduction. This can be easily remembered through the use of mnemonic devices.
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Xanthine oxidase (XO, sometimes XAO) is a form of xanthine oxidoreductase, a type of enzyme that generates reactive oxygen species. These enzymes catalyze the oxidation of hypoxanthine to xanthine and can further catalyze the oxidation of xanthine to uric acid. These enzymes play an important role in the catabolism of purines in some species, including humans. Xanthine oxidase is defined as an enzyme activity (EC 1.17.3.2).
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Groundwater remediation of TCP can occur through in situ chemical oxidation, permeable reactive barriers, and other remediation techniques. Several TCP remediation strategies have been studied and/or applied with varying degrees of success. These include extraction with granular activated carbon, in situ chemical oxidation, and in situ chemical reduction. Recent studies suggest that reduction with zerovalent metals, particularly zerovalent zinc, may be particularly effective in TCP remediation.
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Smooth clean surface (SCS) and eco pickled surface (EPS) are more recent alternatives. In the SCS process, surface oxidation is removed using an engineered abrasive and the process leaves the surface resistant to subsequent oxidation without the need for oil film or other protective coating. EPS is a more direct replacement for acid pickling. Acid pickling relies on chemical reactions while EPS uses mechanical means.
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Methanogens rely on such enzymes to catalyze the reduction of CO2, to methane. One step in methanogenesis entails conversion of a methenyl group (formic acid oxidation state) to a methylene group (formaldehyde oxidation state). Among the hydrogenase family of enzymes, Hmd is unique in that it does not directly reduce CO2 to CH4. The natural substrate of the enzyme is the organic compound methenyltetrahydromethanopterin.
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The oxidation of wine is perhaps the most common of wine faults, as the presence of oxygen and a catalyst are the only requirements for the process to occur. Oxidation can occur throughout the winemaking process, and even after the wine has been bottled. Anthocyanins, catechins, epicatechins and other phenols present in wine are those most easily oxidised,duToit, W.J. (2005). Oxygen in winemaking: Part I. WineLand.
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In a related process, oxidation of a cold mixture of para-aminodimethylaniline and meta- toluylenediamine gives toluylene blue. This indamine is formed as an intermediate product and passing into the red when boiled; and also by the oxidation of dimethylparaphenylene diatnine with metatoluylene diamine. It crystallizes in orange-red needles and its alcoholic solution fluoresces strongly. It dyes silk and mordanted cotton a fine scarlet.
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Fluorine forms two halides with tellurium: the mixed- valence and . In the +6 oxidation state, the structural group occurs in a number of compounds such as , , , and . The square antiprismatic anion is also attested. The other halogens do not form halides with tellurium in the +6 oxidation state, but only tetrahalides (, and ) in the +4 state, and other lower halides (, , , and two forms of ).
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At around 250 °C it will react with chlorine or bromine, and under certain hot conditions will react with iodine. Finely divided tungsten is pyrophoric. The most common formal oxidation state of tungsten is +6, but it exhibits all oxidation states from −2 to +6. Tungsten typically combines with oxygen to form the yellow tungstic oxide, WO3, which dissolves in aqueous alkaline solutions to form tungstate ions, .
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This enzyme participates in methane metabolism. Prior to the discovery of this enzyme, methanol oxidation in Gram-negative bacteria had been shown to be by way of an (NAD+) independent alcohol dehydrogenase found originally in Pseudomonas M27. This enzyme (EC. 1.1.99.8) contains a prosthetic group called Pyrrolo Quinoline Quinone (PQQ) that accepts the electrons generated from methanol oxidation and passes these electrons to cytochrome c.
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The use of peroxyacids and peroxides when performing the Baeyer–Villiger oxidation can cause the undesirable oxidation of other functional groups. Alkenes and amines are a few of the groups that can be oxidized. For instance, alkenes in the substrate, particularly when electron-rich, may be oxidized to epoxides. However, methods have been developed that will allow for the tolerance of these functional groups.
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The limonene which is the main component of the oil is a mild irritant, as it dissolves protective skin oils. Limonene and its oxidation products are skin irritants, and limonene-1,2-oxide (formed by aerial oxidation) is a known skin sensitizer. Most reported cases of irritation have involved long-term industrial exposure to the pure compound, e.g. during degreasing or the preparation of paints.
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In addition to metabolism by FAAH, COX-2 and LOXs, NAE 20:4 (AEA) can also undergo oxidation by several of human cytochrome P450 (CYPs) enzymes, resulting in various oxidized lipid species, some of which have biological relevance as CYP-derived epoxides, that can act as a potent agonist of CB2 receptors. Similar pathways of hydrolysis or oxidation of NAEs are also found in plant cells.
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One of the major technical issue facing biodiesel is its susceptibility to oxidation upon exposure to oxygen in ambient air. This becomes a major issue when stored for extended periods of time. This susceptibility is due to its content of unsaturated fatty acid chains. Besides the presence of air, various other factors influence the oxidation process of biodiesel including presence of light, elevated temperature.
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A number of ruthenium-aqua complexes catalyze the oxidation of water. Most catalysts feature bipyridine and terpyridine ligands. Catalysts containing pyridine-2-carboxylate exhibit rates (300 s−1) comparable to that of photosystem II. Work in this area has ushered in many new polypyridyl ligands.. The "blue dimer" {[Ru(bipyridine)2(OH2)]2O}4+ and two derivatives are catalysts (and intermediates) in water oxidation.
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Yin, Q.; Tan, J. M.; Besson, C.; Geletii, Y. V.; Musaev, D. G.; Kuznetsov, A. E.; Luo, Z.; Hardcastle, K. I.; Hill, C. L., A fast soluble carbon-free molecular water oxidation catalyst based on abundant metals. Science 2010, 328, 342-345. Some iron complexes catalyze water oxidation. A water-soluble complex [Fe(OTf)2(Me2Pytacn)] (Pytacn=pyridine- substituted trimethyltriazacyclononane; OTf= triflate) is an efficient WOC.
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The concentration of the catalyst and the oxidant were found to be strongly affecting the oxidation process. Many related complexes with cis labile sites are active catalysts. Most complexes were found to undergo degradation in a few hours. Higher stability of the molecular catalyst may be achieved using robust clathrochelate ligands that stabilize high oxidation states of iron and prevent rapid degradation of the catalyst.
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Bleomycin is a polypeptide antibiotic derived from a fungus, Streptomyces verticillus. Its mechanism of action involves bleomycin binding to guanine bases in deoxyribonucleic acid (DNA) with the oxidation of ferrous iron to ferric iron. The oxidation donates an electron that the oxygen accepts to form a reactive species of oxygen. The reactive oxygen entities attack DNA bases which store information, and thus inhibits DNA synthesis.
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Lactoperoxidase-catalysed reactions yield short-lived intermediary oxidation products of SCN−, providing antibacterial activity. The major intermediary oxidation product is hypothiocyanite OSCN−, which is produced in an amount of about 1 mole per mole of hydrogen peroxide. At the pH optimum of 5.3, the OSCN− is in equilibrium with HOSCN. The uncharged HOSCN is considered to be the greater bactericidal of the two forms.
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The tyrosinyl radical participates in the catalytic cycle: 1e-oxidation is effected by the Cu(II/I) couple and the 1e oxidation is effected by the tyrosyl radical, giving an overall 2e change. The radical abstraction is fast. Anti-ferromagnetic coupling between the unpaired spins of the tyrosine radical ligand and the d9 CuII center gives rise to the diamagnetic ground state, consistent with synthetic models.
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Before the Great Oxygenation Event, copper was not readily available for living organisms. Most early copper was Cu+ and Cu. This oxidation state of copper is not very soluble in water. One billion years ago, after the great oxidation event the oxygen pressure rose sufficiently to oxidise Cu+ to Cu2+, increasing its solubility in water. As a result, the copper became much more available for living organisms.
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Conjugates that were formed were predominated by sulfate conjugates over glucuronide conjugates by a ratio of 6:1. The metabolism of o-toluidine involves many competing activating and deactivating pathways, including N-acetylation, N-oxidation and N-hydroxylation, and ring oxidation. 4-Hydroxylation and N-acetylation of toluidine are the major metabolic pathways in rats. The primary metabolism of o-toluidine takes place in the endoplasmic reticulum.
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Chemically, the most common oxidation states of iron are iron(II) and iron(III). Iron shares many properties of other transition metals, including the other group 8 elements, ruthenium and osmium. Iron forms compounds in a wide range of oxidation states, −2 to +7. Iron also forms many coordination compounds; some of them, such as ferrocene, ferrioxalate, and Prussian blue, have substantial industrial, medical, or research applications.
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This in turn increases or decreases the rate of ATP production by the mitochondrion, and thus the availability of ATP to the cell. Acetyl-CoA, on the other hand, derived from pyruvate oxidation, or from the beta-oxidation of fatty acids, is the only fuel to enter the citric acid cycle. With each turn of the cycle one molecule of acetyl-CoA is consumed for every molecule of oxaloacetate present in the mitochondrial matrix, and is never regenerated. It is the oxidation of the acetate portion of acetyl-CoA that produces CO2 and water, with the energy thus released captured in the form of ATP.
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According to metallurgist Jack Harris, "Oxidation is usually accompanied by a net expansion so that when it occurs in a confined space stresses are generated in the metal component itself or in any surrounding medium such as stone or cement. So much energy is released by oxidation that the stresses generated are of sufficient magnitude to deform or fracture all known materials." As early as 1915, it was recognized that certain modern metal alloys are more susceptible to excessive oxidation when subjected to weathering than other metals. At that time, there was a trend to replace wrought iron fasteners with mild steel equivalents, which were less expensive.
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There is an international disagreement on the definition of white tea between China and other producing countries, where in China the term is applied primarily to tea varieties made through the white tea process while in other countries the term is used generally for teas made through the process. ; Oolong tea: This tea's oxidation is stopped somewhere between the standards for green tea and black tea. The processing typically takes two to three days from withering to drying with a relatively short oxidation period of several hours. In this regard, most Darjeeling teas with light oxidation levels are more similar to green or oolong teas.
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The oxidation of metal sulfide (by oxygen) is slow without colonization by acidophiles, particularly Acidithiobacillus ferrooxidans (synonym Thiobacillus ferrooxidans). These bacteria can accelerate pyritic oxidation by 106 times. In that study, a proposal for the rate at which A.ferrooxidans can oxidise pyrite is the ability to use ferrous iron to generate a ferric iron catalyst : :Fe2+ \+ 1/4O2 \+ H+ → Fe3+ \+ 1/2H2O Under the above acidic conditions, ferric iron (Fe3+) is a more potent oxidant than oxygen, resulting in faster pyrite oxidation rates. A.ferrooxidans is a chemolithoautotrophic bacteria, due to the oligotrophic nature (low dissolved organic carbon concentration) of acidic environments, and their lack of illumination for phototrophy.
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When fasting, the activation of lipolysis provides fatty acids as the preferred fuel source for respiration. In the liver β-oxidation of fatty acids fulfills the local energy needs and may lead to ketogenesis (creating ketone bodies out of fatty acids.) The ketone bodies are then used to meet the demands of tissues other than the liver. The inhibition of glucose oxidation causes fatty acids and ketone bodies to contribute to a glucose- sparing effect, which is an essential survival mechanism for the brain during times of starvation. This inhibition of glucose oxidation at the level of pyruvate dehydrogenase preserves pyruvate and lactate, both of which are gluconeogenic precursors.
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The mechanism of the Saegusa–Ito oxidation involves coordination of palladium to the enol olefin followed by loss of the silyl group and formation of an oxoallyl-palladium complex. β-hydride elimination yields the palladium hydride enone complex which upon reductive elimination yields the product along with acetic acid and Pd0.Oxidation , Chem 215 lecture notes The reversibility of the elimination step allows equilibration, leading to the thermodynamic E-selectivity in acyclic substrates. It has been shown that the product can form a stable Pd0-olefin complex, which may be responsible for the difficulty with re-oxidation seen in catalytic variants of the reaction.
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The Shilov system was discovered by Alexander E. Shilov in 1969-1972 while investigating H/D exchange between isotopologues of CH4 and H2O catalyzed simple transition metal coordination complexes. The Shilov cycle is the partial oxidation of a hydrocarbon to an alcohol or alcohol precursor (RCl) catalyzed by PtIICl2 in an aqueous solution with [PtIVCl6]2− acting as the ultimate oxidant. The cycle consists of three major steps, the electrophilic activation of the C-H bond, oxidation of the complex, and the nucleophilic oxidation of the alkane substrate. An equivalent transformation is performed industrially by steam reforming methane to syngas then reducing the carbon monoxide to methanol.
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This is found to be most prominent in a broad range of sulfur or acetylenic compounds. Sulfur- containing compounds, including ammonium thiosulfate (a popular inhibitor) are found to operate by producing volatile compounds with strong inhibitory effects such as carbon disulfide and thiourea. In particular, thiophosphoryl triamide has been a notable addition where it has the dual purpose of inhibiting both the production of urease and nitrification. In a study of inhibitory effects of oxidation by the bacteria Nitrosomonas europaea, the use of thioethers resulted in the oxidation of these compounds to sulfoxides, where the S atom is the primary site of oxidation by AMO.
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Pentacene is a popular choice for research on organic thin-film transistors and OFETs, being one of the most thoroughly investigated conjugated organic molecules with a high application potential due to a hole mobility in OFETs of up to 5.5 cm2/(V·s), which exceeds that of amorphous silicon. Pentacene, as well as other organic conductors, is subject to rapid oxidation in air, which precludes commercialization. If the pentacene is preoxidized, the pentacene-quinone is a potential gate insulator, then the mobility can approach that of rubrene – the highest-mobility organic semiconductor – namely, 40 cm2/(V·s). This pentacene oxidation technique is akin to the silicon oxidation used in the silicon electronics.
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This suggests that its natural electron acceptor may be a periplasmic cytochrome c of similarly high potential, which would couple the ethylbenzene oxidation to the nitrate respiration of A. aromaticum. The EBDH catalytic cycle has two parts: i) oxidation part, where substrate is oxidized to alcohols and the enzyme is reduced to its catalytically inactive form, and ii) enzyme re-oxidation part, where EBDH active site (MoCo) is oxidized and restored to its catalytically active form. Recent theoretical and experimental studies point toward radical C-H activation as the initial reaction and rate limiting step. A possible alternative hydride transfer seems to be less likely.
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Electro-oxidation has recently grown in popularity thanks to its ease of set-up and effectiveness in treating harmful and recalcitrant organic pollutants, which are typically difficult to degrade with conventional wastewater remediation processes. Also, it does not require any external addition of chemicals (contrarily to other processes like in-situ chemical oxidation), as the required reactive species are generated at the anode surface. Electro-oxidation has been applied to treat a wide variety of harmful and non-biodegradable contaminants, including aromatics, pesticides, drugs and dyes. Due to its relatively high operating costs, it is often combined with other technologies, such as biological remediation.
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In 1955, Scientific Design created another technique, the Mid-Century process of bromine-assisted oxidation of paraxylene to create terephthalic acid. Studying transformations of para-substituted aromatic compounds for use in the Witten Process, Landau's group experimented with a broad range of metal catalysts, solvent media, and oxidation initiators under varying temperatures and pressures. They discovered that a metal catalyst, manganese bromide or cobalt bromide, proved highly effective when used with acetic acid as the solvent medium and oxygen from compressed air as the oxidant. Eventually, experimenters achieved yields of terephthalic acid at 90% of the theoretically possible yield, through a one-pass batch oxidation process.
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In mice, LCAD deficient mice have been shown to expend less energy, and are also subject to hypothermia, which can be explained by the fact that a reduced rate of fatty acid oxidation is correlated with a lowered capacity to generate heat. Indeed, when LCAD mice are exposed to the cold, the expression of fatty acid oxidation genes was elevated in liver. As ACADL is a mitochondrial protein, and a member of the beta-oxidation family, there are many instances in which its deficiency is correlated with mitochondrial dysfunction and the diseases that manifest as a result. The ACADL gene has been correlated with protecting against diabetes.
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These difficult to control organics have been proven to impact yield and device performance especially at the most demanding process steps. One of the successful examples of the POU organics control down to 0.5 ppb TOC level is AOP combining ammonium persulfate and UV oxidation (refer to the persulfate+UV oxidation chemistry in the TOC measurement section). Available proprietary POU advanced oxidation processes can consistently reduce TOC to 0.5 parts per billion (ppb) in addition to maintaining consistent temperature, oxygen and particles exceeding the SEMI F063 requirements. This is important because the slightest variation can directly affect the manufacturing process, significantly influencing product yields.
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Combining operando Raman, UV–Vis and ATR-IR is particularly useful for studying homogeneous catalysis in solution. Transition-metal complexes can perform catalytic oxidation reactions on organic molecules; however, much of the corresponding reaction pathways are still unclear. For example, an operando study of the oxidation of veratryl alcohol by salcomine catalyst at high pH determined that the initial oxidation of the two substrate molecules to aldehydes is followed by the reduction of molecular oxygen to water, and that the rate determining step is the detachment of the product. Understanding organometallic catalytic activity on organic molecules is incredibly valuable for the further development of material science and pharmaceuticals.
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An example of a Frost diagram for the element manganese A Frost diagram or Frost–Ebsworth diagram is a type of graph used by inorganic chemists in electrochemistry to illustrate the relative stability of a number of different oxidation states of a particular substance. The graph illustrates the free energy vs oxidation state of a chemical species. This effect is dependent on pH, so this parameter also must be included. The free energy is determined by the oxidation–reduction half-reactions. The Frost diagram allows easier comprehension of these reduction potentials than the earlier-designed Latimer diagram, because the “lack of additivity of potentials” was confusing.
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Dimethylaniline monooxygenase [N-oxide-forming] 1 is an enzyme that in humans is encoded by the FMO1 gene. Metabolic N-oxidation of the diet-derived amino- trimethylamine (TMA) is mediated by flavin-containing monooxygenase and is subject to an inherited FMO3 polymorphism in humans resulting in a small subpopulation with reduced TMA N-oxidation capacity resulting in fish odor syndrome Trimethylaminuria. Three forms of the enzyme, FMO1 found in fetal liver, FMO2 found in adult liver, and FMO3 are encoded by genes clustered in the 1q23-q25 region. Flavin-containing monooxygenases are NADPH-dependent flavoenzymes that catalyzes the oxidation of soft nucleophilic heteroatom centers in xenobiotics such as pesticides and drugs.
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Dimethylaniline monooxygenase [N-oxide-forming] 5 is an enzyme that in humans is encoded by the FMO5 gene. Metabolic N-oxidation of the diet-derived amino- trimethylamine (TMA) is mediated by flavin-containing monooxygenase and is subject to an inherited FMO3 polymorphism in man resulting in a small subpopulation with reduced TMA N-oxidation capacity resulting in fish odor syndrome Trimethylaminuria. Three forms of the enzyme, FMO1 found in fetal liver, FMO2 found in adult liver, and FMO3 are encoded by genes clustered in the 1q23-q25 region. Flavin-containing monooxygenases are NADPH-dependent flavoenzymes that catalyzes the oxidation of soft nucleophilic heteroatom centers in drugs, pesticides, and xenobiotics.
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Carey, F.A.; Sundberg, R.J. Advanced Organic Chemistry: Part A: Structure and Mechanism; Kluwer Academic/Plenum Publishers: New York, 2000; 327-334. center An intriguing case of σ-bishomoaromaticity can be found in the dications of pagodanes. In these 4-center-2-electron systems the delocalization happens in the plane that is defined by the four carbon atoms (prototype for the phenomenon of σ-aromaticity is cyclopropane which gains about 11.3 kcal mol−1 stability from the effect). The dications are accessible either via oxidation of pagodane or via oxidation of the corresponding bis-seco-dodecahedradiene: Oxidation of pagodane and dodecahedradiene to a sigma-bishomoaromatic dication.
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Thianthrene is a sulfur-containing heterocyclic chemical compound. It is a derivative of the parent heterocycle called dithiin. It is notable for its ease of oxidation.
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The Grenache vins doux naturels can be made in an oxidised or unoxidised style whereas the Muscat wines are protected from oxidation to retain their freshness.
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A common oxidation example is when a natural ferrous iron mineral such as pyrite is oxidized to form goethite or other ferric iron hydroxides or sulfates.
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Reduction, deprotection, and oxidation afforded 9. On treatment with oxygen in warm ethyl acetate, the aldehyde on 9 was oxidized to the acyl radical for decarbonylation.
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The Ni(0) catalyst involves oxidation addition of a P-H bond to the metal, followed by insertion of the alkene into the M-H bond.
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A freshly broken rock shows differential chemical weathering (probably mostly oxidation) progressing inward. This piece of sandstone was found in glacial drift near Angelica, New York.
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Dithiiranes are three membered rings containing two sulfur atoms and one carbon. One example was prepared by oxidation of a 1,3-dithietane. Structure of a dithiirane.
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Plasma electrolytic oxidation is a similar process, but where higher voltages are applied. This causes sparks to occur and results in more crystalline/ceramic type coatings.
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In conjunction with vanadium oxide, it is used as a catalyst for the oxidation of aromatic compounds in the synthesis of carboxylic acids and acid anhydrides.
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Germanium dichloride is a chemical compound of germanium and chlorine with the formula GeCl2. It is a solid and contains germanium in the +2 oxidation state.
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The Iodite ion, or iodine dioxide anion, is the halite with the chemical formula . Within the ion the Iodine exists in the oxidation state of +3.
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The precursor to nylon, adipic acid, is produced on a large scale by oxidation of "KA oil"—a mixture of cyclohexanone and cyclohexanol—with nitric acid.
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The lactate shuttle hypothesis also explains the balance of lactate production in the cytosol, via glycolysis or glycogenolysis, and lactate oxidation in the mitochondria (described below).
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Platinum(IV) chloride is the inorganic compound of platinum and chlorine with the empirical formula PtCl4. This brown solid features platinum in the 4+ oxidation state.
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The Mining and Smelting Magazine. Ed. Henry Curwen Salmon. Vol. iv, July–Dec 1963, p. 87. Thallium tends to form the +3 and +1 oxidation states.
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3-hydroxyisobutyrate dehydrogenase is a tetrameric mitochondrial enzyme that catalyzes the NAD+-dependent, reversible oxidation of 3-hydroxyisobutyrate, an intermediate of valine catabolism, to methylmalonate semialdehyde.
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Meisserite is associated with other sulfate minerals: belakovskiite, johannite, chalcanthite, copiapite, ferrinatrite, and gypsum.It is resulting from post- mining oxidation of the primary uranium mineral - uraninite.
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Butyryl phosphate is an intermediate in the fermentation of butyric acid. The glutamate oxidation of butyryl phosphate may provide the main source of energy for Clostridium tetanomorphum.
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Infrared spectroscopy shows formation of carbonyl groups, epoxides, and peroxides. Coating with polyethylene or wax can slow the oxidation temporarily, while coating with glass increases stability indefinitely.
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Loose heme can cause oxidation of endothelial and LDL proteins, which results in plaques. Glycation pathway via Amadori Rearrangement (in HbA1c, R is typically N-terminal valine).
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On the other hand, Micro nutrients include; vitamins, minerals, enzymes, protect cells and DNA from oxidation damages which is evident in the inflammation response and recovery process.
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These are good basis for 2nd class picks. Ex 16 is for Alitame proper. Although, in Ex 17, oxidation to the sulfonyl can reduce activity to 1000.
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Hydroxylation of an N-methyl group leads to expulsion of a molecule of formaldehyde, while oxidation of the O-methyl groups takes place to a lesser extent.
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It is used in a wide range of applications. For example, it is used as a catalyst for the hydrochlorination of acetylene, or the oxidation of sulfides.
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A deficiency in this gene product reduces myocardial fatty acid beta-oxidation and is associated with cardiomyopathy. Alternative splicing results in multiple transcript variants encoding different isoforms.
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In 2007, Gerhard Ertl won the Nobel Prize in Chemistry for determining the detailed molecular mechanisms of the catalytic oxidation of carbon monoxide over platinum (catalytic converter).
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Fatty acid oxidation inhibitors are a new potent class of drugs used in treatment of stable angina pectoris and an addition in treatment of chronic heart failure.
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Halazone can be prepared by chlorination of p-sulfonamidobenzoic acid. Another synthesis route is the oxidation of dichloramine-T with potassium permanganate in a mild alkaline medium.
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The most famous example is ferrocenium, [Fe(C5H5)2]+, the blue iron(III) complex derived from oxidation of orange iron(II) ferrocene (few metallocene anions are known).
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Because of their similar activities, luciferase is able to replace fatty acyl-CoA synthetase and convert long-chain fatty acids into fatty-acyl CoA for beta oxidation.
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In this reaction, a carbon has been oxidized through the formation of a covalent bond with oxygen. Formation of a carboxylic acid through the oxidation an aldehyde.
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Evolutionary conserved protein domain corresponding to oxidoreductase activity. NAD binding catalyzes redox reactions to alter the oxidation state of metal ions, using NADP+ as an electron acceptor.
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Sulfuric acid is commonly added to solutions to reduce oxidation to ferric iron. It is used in the Fricke's dosemeter to measure high doses of gamma rays.
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"Salen-type" metal complexes are formed with ligands with similar chelating groups, such as acacen, salph, and salqu. Salqu copper complexes have been investigated as oxidation catalysts.
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Some of the secondary bonds impart cohesion and are connected with packing. Stibnite is grey when fresh, but can turn superficially black due to oxidation in air.
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Flavobacterium sp. [85] and Pseudomonas sp. (NK87) degrade oligomers of Nylon 6, but not polymers. Certain white rot fungal strains can also degrade Nylon 6 through oxidation.
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In these magnesium can be considered to be in oxidation state +1 rather than the normal +2. However these sort of compounds are not made from HMgMgH.
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The influent solution was sparged continuously with N2 gas to maintain anoxic conditions for the bacteria and to prevent aerobic oxidation of the materials in the wastewater.
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To control the size of micro and nano-scale components, the use of so-called etchless processes is often applied. This approach to MEMS fabrication relies mostly on the oxidation of silicon, as described by the Deal-Grove model. Thermal oxidation processes are used to produced diverse silicon structures with highly precise dimensional control. Devices including optical frequency combs,Silicon-chip mid-infrared frequency comb generation Nature, 2015.
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Domain III contains a CXC Cu binding motif and performs the Cu insertion and subsequent disulfide oxidation of SOD1. When CCS docks to SOD1, cysteine 244 of CCS and 57 of SOD1 form a disulfide linkage. This disulfide bond is then transferred to form a disulfide bridge between cysteine 57 and 146 of SOD1. CCS's catalytic oxidation of SOD1's disulfide bridge can only be performed in the presence of oxygen.
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Following glycolysis, the citric acid cycle is activated by the production of acetyl-CoA. The oxidation of pyruvate by pyruvate dehydrogenase in the matrix produces CO2, acetyl-CoA, and NADH. Beta oxidation of fatty acids serves as an alternate catabolic pathway that produces acetyl-CoA, NADH, and FADH2. The production of acetyl-CoA begins the citric acid cycle while the co- enzymes produced are used in the electron transport chain.
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Fenton's reagent in particular is highly exothermic and can cause unwanted effects on microbial life in the aquifer if it is not used carefully or stabilized. Further challenges associated with ISCO include the generation of unwanted or toxic oxidation products. Recent evidence suggests that the oxidation of benzene results in the formation of phenol (a relatively benign compound) and a novel aldehyde side-product, the toxicology of which is unknown.
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Resistance to oxidation is very important because NASA wants to be able to reuse shuttle materials. TGA can be used to study the static oxidation of materials such as these for practical use. Combustion during TG analysis is identifiable by distinct traces made in the TGA thermograms produced. One interesting example occurs with samples of as-produced unpurified carbon nanotubes that have a large amount of metal catalyst present.
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Procyanidin A1 is an A type proanthocyanidin dimer. It is an epicatechin-(2β→7,4β→8)-catechin dimer found in Rhododendron spiciferum, in peanut skins and in Ecdysanthera utilis. Procyanidin B1 can be converted into procyanidin A1 by radical oxidation using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals under neutral conditions.Conversion of procyanidin B-type (catechin dimer) to A-type: evidence for abstraction of C-2 hydrogen in catechin during radical oxidation.
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Molybdenum is a transition metal with an electronegativity of 2.16 on the Pauling scale. It does not visibly react with oxygen or water at room temperature. Weak oxidation of molybdenum starts at ; bulk oxidation occurs at temperatures above 600 °C, resulting in molybdenum trioxide. Like many heavier transition metals, molybdenum shows little inclination to form a cation in aqueous solution, although the Mo3+ cation is known under carefully controlled conditions.
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Acetaldehyde subsequently accumulates and begins to form covalent bonds with cellular macromolecules, forming toxic adducts that, eventually, lead to death of the cell. This same excess of NADH from ethanol oxidation causes the liver to move away from fatty acid oxidation, which produces NADH, towards fatty acid synthesis, which consumes NADH. This consequent lipogenesis is believed to at least largely underlie the pathogenesis of alcoholic fatty liver disease.
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Side products were a wide range of carboxylic acids and oxidation products such as alcohols, aldehydes, esters, or ketones. The oxidation of paraffins was carried out in the liquid phase by molecular oxygen, e.g. by aerating with oxygen or atmospheric air, in the presence of catalysts such as permanganates, e.g. 0.1% - 0.3% potassium permanganate, at temperatures in the range of about 100 to 120 °C and under atmospheric pressure.
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These enzymes are localized in almost all cellular compartments, such as endoplasmic reticulum, cytosol, mitochondria, and peroxisomes. They are highly regulated by peroxisome proliferator activated receptors, which led to their involvement in lipid metabolism. The enzyme is up-regulated during times of increased fatty acid oxidation, which suggests that this enzyme has a potential role the peroxisomal beta-oxidation. The systematic name of this enzyme class is palmitoyl-CoA hydrolase.
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In the Hooker reaction (1936) an alkyl chain in a certain naphthoquinone (phenomenon first observed in the compound lapachol) is reduced by one methylene unit as carbon dioxide in each potassium permanganate oxidation.On the Oxidation of 2-Hydroxy-1,4-naphthoquinone Derivatives with Alkaline Potassium Permanganate Samuel C. Hooker J. Am. Chem. Soc. 1936; 58(7); 1174–79. On the Oxidation of 2-Hydroxy-1,4-naphthoquinone Derivatives with Alkaline Potassium Permanganate.
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Iridium tetroxide (IrO4, Iridium(VIII) oxide) is a binary compound of oxygen and iridium in oxidation state +8. This compound was formed by photochemical rearrangement of (η1-O2)IrO2 in solid argon at a temperature of . At higher temperatures, the oxide is unstable. The detection of the iridium tetroxide cation by infrared photodissociation spectroscopy with formal oxidation state +9 has been reported, the highest currently known of any element.
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Following the formation of porous silicon, its surface is covered with covalently bonded hydrogen. Although the hydrogen coated surface is sufficiently stable when exposed to inert atmosphere for a short period of time, prolonged exposure render the surface prone to oxidation by atmospheric oxygen. The oxidation promotes instability in the surface and is undesirable for many applications. Thus, several methods were developed to promote the surface stability of porous silicon.
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An approach that can be taken is through thermal oxidation. The process involves heating the silicon to a temperature above 1000 C to promote full oxidation of silicon. The method reportedly produced samples with good stability to aging and electronic surface passivation.Chazalviel J. N., Ozanam F. 1997, "Surface modification of porous silicon", in Properties of Porous Silicon, Canham, L. T., Institution of Engineering and Technology, London, pp. 59–65.
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Other factors that increases the rate of oxidation includes increasing pH and increased sodium carbonate concentration. The reaction rate eventually levels off due to the maximum formation of the product within the oxidation process. Quinaldine red also has the ability to fluoresce. Free quinaldine red does not fluoresce in solution when it is not bound to anything, making quinaldine red only visible by fluorescence when it is bound to something.
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So, the chemical composition of TBV, relating to the AAB oxidation products, is highly variable and depends on several factors such as the type of grape must, cooking modality, oxidation temperature, and others. The acetification process and the growth of relevant bacteria are mainly affected by the alcohol, sugar, and acetic acid content.Gullo, M. and Giudici, P. (2006). Isolation and selection of acetic acid bacteria strains for traditional balsamic vinegar.
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Gold can be a very active catalyst in oxidation of carbon monoxide (CO), i.e. the reaction of CO with molecular oxygen to produce carbon dioxide (CO2). Supported gold clusters, thin films and nanoparticles are one to two orders of magnitude more active than atomically dispersed gold cations or unsupported metallic gold. Possible mechanism of CO oxidation on an Au catalyst supported on a reducible metal oxide at room temperature.
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This often happens when ferrous ions come into contact with water (due to dissolved oxygen within surface waters) and a water-mineral reaction occurs. The formula for the oxidation/reduction of iron is: : Fe2+ ↔ Fe3+ \+ e− The formula works for oxidation to the right or reduction to the left. Fe2+ is the ferrous form of iron. This form of iron gives up electrons easily and is a mild reducing agent.
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Less well studied (but probably just as important) enzymatic antioxidants are the peroxiredoxins and the recently discovered sulfiredoxin. Other enzymes that have antioxidant properties (though this is not their primary role) include paraoxonase, glutathione-S transferases, and aldehyde dehydrogenases. The amino acid methionine is prone to oxidation, but oxidized methionine can be reversible. Oxidation of methionine is shown to inhibit the phosphorylation of adjacent Ser/Thr/Tyr sites in proteins.
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Nitrogen is removed through the biological oxidation of nitrogen from ammonia to nitrate (nitrification), followed by denitrification, the reduction of nitrate to nitrogen gas. Nitrogen gas is released to the atmosphere and thus removed from the water. Nitrification itself is a two-step aerobic process, each step facilitated by a different type of bacteria. The oxidation of ammonia (NH3) to nitrite (NO2−) is most often facilitated by Nitrosomonas spp.
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Luck, F. Wet air oxidation: past, present and future. Catalysis Today 1999, 53, 81-91. Mixed metal catalysts, such a Ce/Mn, Co/Ce, Ag/Ce, have also been effective in improving the treatment achieved in a WAO system.Silva, A.; Marques, R.; Quinta-Ferreira, R. Catalyst based in cerium oxide for wet oxidation of acrylic acid in the prevention of environmental risks. Applied Catalysis 2004, 47, 269-279.
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Carroll has developed protein cysteine oxidation as a new paradigm for the regulation of cell signaling pathways. Her group has also examined sulfa- and thioreductase activity in Mycobacterium as potential drug targets to treat diseases like tuberculosis. Carroll incorporates tools such as proteomic labeling and chemical probes to decipher how oxidation of target cysteines in proteins by reactive oxygen species (ROS) leads to downstream changes in cell cycle regulation.
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Bacteria biooxidation is an oxidation process caused by microbes where the valuable metal remains (but becomes enriched) in the solid phase. In this process, the metal remains in the solid phase and the liquid can be discarded. Bacterial oxidation is a biohydrometallurgical process developed for pre- cyanidation treatment of refractory gold ores or concentrates. The bacterial culture is a mixed culture of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans.
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One of the effects of exercise is an increase in fatty acid metabolism, which provides more energy for the cell. One of the key pathways in AMPK's regulation of fatty acid oxidation is the phosphorylation and inactivation of acetyl-CoA carboxylase. Acetyl-CoA carboxylase (ACC) converts acetyl-CoA to malonyl-CoA, an inhibitor of carnitine palmitoyltransferase 1 (CPT-1). CPT-1 transports fatty acids into the mitochondria for oxidation.
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He also described stable complexes of quadrivalent nickel such as the deep blue [Ni(diars)2Cl2] [ClO4]2, by nitric acid oxidation of the trivalent complex.R S Nyholm; Studies in co-ordination chemistry, Part IX: Quadrivalent nickel; J. Chem. Soc.; 1951, 2602–2607 This stabilisation of higher oxidation states became significant in the Nyholm-Rail reaction where the ditertiary arsine, diars undergoes a condensation reaction to a tritertiary arsine, triars.
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Sulfate, which is used in the oxidation of organic matter, is dependent on the surplus of carbon left by aerobic organisms due to oxygen depletion. When a mix of tidal exposure and camel grazing pressure were placed on the habitat, there was a decrease in primary production, which in turn affected sulfate-cycling. A decrease in sulfate- cycling could cause the trees in the forest to slow down their oxidation process.
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Physical, chemical, and biological methods have been used to remediate arsenic contaminated water. Bioremediation is said to be cost-effective and environmentally friendly. Bioremediation of ground water contaminated with arsenic aims to convert arsenite, the toxic form of arsenic to humans, to arsenate. Arsenate (+5 oxidation state) is the dominant form of arsenic in surface water, while arsenite (+3 oxidation state) is the dominant form in hypoxic to anoxic environments.
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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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30 Apr. 2011. . High plasma levels of insulin in the blood plasma (e.g. after meals) cause the dephosphorylation of acetyl-CoA carboxylase, thus promoting the formation of malonyl-CoA from acetyl-CoA, and consequently the conversion of carbohydrates into fatty acids, while epinephrine and glucagon (released into the blood during starvation and exercise) cause the phosphorylation of this enzyme, inhibiting lipogenesis in favor of fatty acid oxidation via beta-oxidation.
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Although these are not found on Earth naturally, boron forms a variety of stable compounds with formal oxidation state less than three. As for many covalent compounds, formal oxidation states are often of little meaning in boron hydrides and metal borides. The halides also form derivatives of B(I) and B(II). BF, isoelectronic with N2, cannot be isolated in condensed form, but B2F4 and B4Cl4 are well characterized.
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Fish oil is widely sold in capsules containing a mixture of omega-3 fatty acids, including EPA and DHA. Oxidized fish oil in supplement capsules may contain lower levels of EPA and DHA. Light, oxygen exposure, and heat can all contribute to oxidation of fish oil supplements. Buying a quality product that is kept cold in storage and then keeping it in a refrigerator can help minimize oxidation.
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The active Nicotinamide group on the molecule NAD+ undergoes oxidation in many metabolic pathways. Nicotinamide, as a part of the coenzyme nicotinamide adenine dinucleotide (NADH / NAD+) is crucial to life. In cells, nicotinamide is incorporated into NAD+ and nicotinamide adenine dinucleotide phosphate (NADP+). NAD+ and NADP+ are coenzymes in a wide variety of enzymatic oxidation-reduction reactions, most notably glycolysis, the citric acid cycle, and the electron transport chain.
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Secondary treatment by biochemical oxidation of dissolved and colloidal organic compounds is widely used in sewage treatment and is applicable to some agricultural and industrial wastewaters. Biological oxidation will preferentially remove organic compounds useful as a food supply for the treatment ecosystem. Concentration of some less digestible compounds may be reduced by co-metabolism. Removal efficiency is limited by the minimum food concentration required to sustain the treatment ecosystem.
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Carnitine synthesis To ensure a continuous guarantee of energy supply, the body oxidises considerable amounts of fat along with glucose. Carnitine transports activate long-chain fatty acids (FA) from the cytosol of the cell into the mitochondrion and is therefore essential for fatty acid oxidation (known as beta oxidation). Carnitine is mainly absorbed from the diet, but can be formed through biosynthesis. To produce carnitine, lysine residues are methylated to trimethyllysine.
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