137 Sentences With "oxidations" | Random Sentence Generator

PCC also effects allylic oxidations, for example, in conversion of dihydrofurans to furanones.

Oxidations involving selenium dioxide are often carried out with catalytic amounts of the selenium compound and in presence of a sacrificial catalyst or co-oxidant such as hydrogen peroxide. SeO2-based oxidations sometimes afford carbonyl compounds such as ketones,Organic Syntheses Coll. Vol.

Several chromium oxides are used for related oxidations. These include Jones oxidation and Sarett oxidation.

Olefin metathesis is usually catalyzed heterogeneously in industry, but homogeneous variants are valuable in fine chemical synthesis. ;Oxidations Homogeneous catalysts are also used in a variety of oxidations. Is the Wacker process, acetaldehyde is produced from ethylene and oxygen. Many non-organometallic complexes are also widely used in catalysis, e.g.

It dissolves in water to give perrhenic acid. It is a precursor to methylrhenium trioxide ("MTO"), a catalyst for oxidations.

It also contributes to the degradation of very long-chain fatty acids by catalyzing successive ω-oxidations and chain shortening.

In oxidations of alcohols or aldehydes into carboxylic acids, chromic acid is one of several reagents, including several that are catalytic. For example, nickel(II) salts catalyze oxidations by bleach (hypochlorite). Aldehydes are relatively easily oxidised to carboxylic acids, and mild oxidising agents are sufficient. Silver(I) compounds have been used for this purpose.

The intermolecular oxidations of olefins with alcohols as nucleophile typically generate ketals, where as the palladium-catalyzed oxidations of olefins with carboxylic acids as nucleophile genreats vinylic or allylic carboxylates. In case of diols, their reactions with alkenes typically generate ketals, whereas reactions of olefins bearing electron-withdrawing groups tend to form acetals. Palladium- catalyzed intermolecular oxidations of dienes with carboxylic acids and alcohols as donors give 1,4-addition products. In the case of cyclohexadiene (Figure 4, A), Backvall found that stereochemical outcome of product was found to depend on concentration of LiCl.

Collins reagent is especially useful for oxidations of acid sensitive compounds. Primary and secondary alcohols are oxidized respectively to aldehydes and ketones in yields of 87-98%. Like other oxidations by Cr(VI), the stoichiometry of the oxidations is complex because the metal undergoes 3e reduction and the substrate is oxidized by 2 electrons: :3 RCH2OH + 2 CrO3(pyridine)2 → 3 RCHO + 3 H2O + Cr2O3 \+ 4 pyridine The reagent is typically used in a sixfold excess. Methylene chloride is the typical solvent, with the solubility of 12.5 g/100 mL.

Proposed oxidations of compounds in guaiac oil as explanation for the formation of the blue bis-methylenequinone as part of the guaiac test.

K. Barry Sharpless shared the 2001 Nobel Prize in Chemistry for his work on asymmetric oxidations. The prize was shared with William S. Knowles and Ryōji Noyori.

Many molybdenum oxides are used as heterogeneous catalysts, e.g. for oxidations. Molybdic acid and its salts are used to make the Froehde reagent for the presumptive identification of alkaloids.

Since most of these methods employ dimethylsulfoxide (DMSO) as oxidant and generate dimethylsulfide, these are often colloquially summarized as DMSO- oxidations. Conceptually, generating an aldehyde and dimethylsulfide from an alcohol and DMSO requires a dehydrating agent for removal of H2O, ideally an electrophile simultaneously activating DMSO. In contrast, methods generating the sulfonium intermediate from dimethylsulfide do not require a dehydrating agent. Closely related are oxidations mediated by dimethyl selenoxide and by dimethyl selenide.

"Prior to the nineteenth century and the advent of modern chemistry they [fireworks] must have been relatively dull and unexciting." Bertholet in 1786 discovered that oxidations with potassium chlorate resulted in a violet emission. Subsequent developments revealed that oxidations with the chlorates of barium, strontium, copper, and sodium result in intense emission of bright colors. The isolation of metallic magnesium and aluminium marked another breakthrough as these metals burn with an intense silvery light.

Subsequent decarboxylation and three p450-type oxidations leads to harpagide. Cinnamoyl esterification at the 3-hydroxyl position leads to the natural product harpagoside. Figure 1: Proposed biosynthetic pathway of harpagoside.

The most common use for DMDO is the oxidation of alkenes to epoxides. One particular advantage of using DMDO is that the only byproduct of oxidation is acetone, a fairly innocuous and volatile compound. DMDO oxidations are particularly mild, sometimes allowing oxidations which might not otherwise be possible. In fact, DMDO is considered the reagent of choice for epoxidation, and in nearly all circumstances is as good as or better than peroxyacids such as meta-chloroperoxybenzoic acid (mCPBA).

Other more convenient or less toxic reagents for oxidizing alcohols include dimethyl sulfoxide, which is used in Swern and Pfitzner–Moffatt oxidations, and hypervalent iodine compounds, such as the Dess–Martin periodinane.

The application of this reagent to oxidations was discovered by G. I. Poos, G. E. Arth, R. E. Beyler and L.H. Sarett in 1953. It was popularized by Collins several years later.

Since oxidative stress commonly produces both free radicals and singlet oxygen, most or all of these products may form together in tissues undergoing oxidative stress. Free radical and singlet oxygen oxidations of linoleic acid produce a similar set of 13-HODE metabolites (see 9-Hydroxyoctadecadienoic acid). Studies attribute these oxidations to be major contributors to 13-HODE production in tissues undergoing oxidative stress including in humans sites of inflammation, steatohepatitis, cardiovascular disease-related atheroma plaques, neurodegenerative disease, etc. (see oxidative stress).

Semi-flexible rod polymers are a kind of organic polymer which may be converted to conductive polymers by appropriate oxidations or doping. Examples include polyaniline, poly(p-phenylene oxide) and poly(p-phenylene sulfide).

This article covers protein engineering of cytochrome (CYP) P450 enzymes. P450s are involved in a range of biochemical catabolic and anabolic process. Natural P450s can perform several different types of chemical reactions including hydroxylations, N,O,S-dealkylations, epoxidations, sulfoxidations, aryl-aryl couplings, ring contractions and expansions, oxidative cyclizations, alcohol/aldehyde oxidations, desaturations, nitrogen oxidations, decarboxylations, nitrations, as well as oxidative and reductive dehalogenations. Engineering efforts often strive for 1) improved stability 2) improved activity 3) improved substrate scope 4) enabled ability to catalyze unnatural reactions.

Several other enzymes have been described later, including HMFO. This flavin dependent oxidase catalyzes the three consecutive oxidations to form FDCA from HMF.W.P. Dijkman, D.E. Groothuis, M.W. Fraaije. Angew. Chem. Int. Ed. 2014, 53: 6515-6518.

BBE-like enzymes serve as a catalyzer for a wide range of reactions. All the way from two-electron oxidations as observed in (At)BBE-like 15 to four- electron oxidations as seen in Dbv29. BBE-like enzymes are involved in the synthesis of plenty of isoquinoline alkaloids such as the conversion of (S)-reticuline to (S)-scoulerineAndreas W., Franz H., Toni M. K., Anton G., and Peter M. Biochemical Evidence That Berberine Bridge Enzyme Belongs to a Novel Family of Flavoproteins Containing a Bi-covalently Attached FAD Cofactor. THE JOURNAL OF BIOLOGICAL CHEMISTRY VOL.

Then, the NSPS cyclizes the polyketide, giving prerapamycin, the first enzyme-free product. The macrocyclic core is then customized by a series of post-PKS enzymes through methylations by MTases and oxidations by P-450s to yield rapamycin.

This intermediate was then subjected to various additions and oxidations to yield the final allopumiliotoxin. The synthesis of (+)-allopumiliotoxin 323B’ has also been achieved using an intermediate from the previous synthesis.Michael, J. P. Nat. Prod. Rep. 2002, 19, 719-741.

IBX exists as two tautomers one of which is the carboxylic acid. The acidity of IBX which has been determined in water (pKa 2.4) and DMSO (pKa 6.65) is known to affect organic reactions, for instance acid-catalyzed isomerization accompanying oxidations.

Cytochrome P450 enzymes perform an assortment of modifications on a variety of ligands, utilizing its large active site and its ability to bind more than one substrate at a time to perform complicated chemical alterations in the metabolism of endogenous and exogenous compounds. These include hydroxylation, epoxidation of olefins, aromatic oxidation, heteroatom oxidations, N- and O- dealkylation reactions, aldehyde oxidations, dehydrogenation reactions, and aromatase activity. Hydroxylation of an sp3 C-H bond is one of the ways in which CYP3A4 (and cytochrome P450 oxygenases) affects its ligand. In fact, hydroxylation is sometimes followed by dehydrogenation, leading to more complex metabolites.

The White–Chen catalyst is an Iron-based coordination complex named after Professor M. Christina White and her graduate student Mark S. Chen. The catalyst is used along with hydrogen peroxide and acetic acid additive to oxidize aliphatic sp3 C-H bonds in organic synthesis. The catalyst is the first to allow for preparative and predictable aliphatic C–H oxidations over a broad range of organic substrates. Oxidations with the catalyst have proven to be remarkably predictable based on sterics, electronics, and stereoelectronics allowing for aliphatic C–H bonds to be thought of as a functional group in the streamlining of organic synthesis.

A method for generating trifluoroperacetic acid in situ for use in Baeyer–Villiger oxidations from sodium percarbonate and trifluoroacetic anhydride has been reported; it provides a convenient and cheap approach to this reagent without the need to obtain highly concentrated hydrogen peroxide.

To investigate the process of enzymatic oxygen activation in organisms Traube did experimental research into inorganic autoxidation and oxygen activation. He thus demonstrated the role of water as active partner in slow oxidations and showed the intermediate character of hydrogen peroxide generation.

There have been attempts to use organometallic catalysts to perform enantioselective Baeyer–Villiger oxidations. The first reported instance of one such oxidation of a prochiral ketone used dioxygen as the oxidant with a copper catalyst. Other catalysts, including platinum and aluminum compounds, followed.

N-Methylmorpholine N-oxide (more correctly 4-methylmorpholine 4-oxide), NMO or NMMO is an organic compound. This heterocyclic amine oxide and morpholine derivative is used in organic chemistry as a co-oxidant and sacrificial catalyst in oxidation reactions for instance in osmium tetroxide oxidations and the Sharpless asymmetric dihydroxylation or oxidations with TPAP.Mark R. Sivik and Scott D. Edmondson "N-Methylmorpholine N-Oxide" E-EROS ENCYCLOPEDIA OF REAGENTS FOR ORGANIC SYNTHESIS, 2008 NMO is commercially supplied both as a monohydrate C5H11NO2·H2O and as the anhydrous compound. The monohydrate is used as a solvent for cellulose in the Lyocell process to produce cellulose fibers.

MPP+ is produced in vivo from the precursor MPTP. The process involves two successive oxidations of the molecule by monoamine oxidase B to form the final MPP+ product. This metabolic process occurs predominantly in astrocytes in the brain. Metabolism of MPTP to MPP+ in cerebral astrocytes.

Bobbitt was born in Charleston, West Virginia. He received a B. S. degree in chemistry from West Virginia University in 1951 and moved to the Ohio State University. At Ohio State, he received a Ph. D. degree with Melville L. Wolfrom in 1955, working on periodate oxidations.

MTO catalyses for the oxidations with hydrogen peroxide. Terminal alkynes yield the corresponding acid or ester, internal alkynes yield diketones, and alkenes give epoxides. MTO also catalyses the conversion of aldehydes and diazoalkanes into an alkene.Hudson, A. (2002) “Methyltrioxorhenium” in Encyclopedia of Reagents for Organic Synthesis.

Metal-catalyzed oxidations with O2 proceed via the intermediacy of dioxygen complexes, although the actual oxidants are often oxo derivatives. The reversible binding of O2 to metal complexes has been used as a means to purify oxygen from air, but cryogenic distillation of liquid air remains the dominant technology.

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.

Cytochrome P450 2E1 (abbreviated CYP2E1, ) is a member of the cytochrome P450 mixed-function oxidase system, which is involved in the metabolism of xenobiotics in the body. This class of enzymes is divided up into a number of subcategories, including CYP1, CYP2, and CYP3, which as a group are largely responsible for the breakdown of foreign compounds in mammals. While CYP2E1 itself carries out a relatively low number of these reactions (~4% of known P450-mediated drug oxidations), it and related enzymes CYP1A2 and CYP3A4 are responsible for the breakdown of many toxic environmental chemicals and carcinogens that enter the body, in addition to basic metabolic reactions such as fatty acid oxidations.

The damage caused can be repaired by subjecting the crystal to high temperature. This process is called annealing. Furnace anneals may be integrated into other furnace processing steps, such as oxidations, or may be processed on their own. Furnace anneals are performed by equipment especially built to heat semiconductor wafers.

In the early part of the last century, a parallel concept called Unit Processes was used to classify reactive processes. Thus oxidations, reductions, alkylations, etc. formed separate unit processes and were studied as such. This was natural considering the close affinity of chemical engineering to industrial chemistry at its inception.

Eight thousand years ago, volcanic fissures of the Askja volcanic system erupted directly underneath the river and glacial ice. This caused explosions and chaotic flooding. The center of the park was Vesturdalur with Hljóðaklettar (rock of echoes). Rauðhólar (red mountain) is of interest because of its special colouring due to iron oxidations.

Podophyllotoxin is present at concentrations of 0.3% to 1.0% by mass in the rhizome of the American mayapple (Podophyllum peltatum). Another common source is the rhizome of Sinopodophyllum hexandrum Royle (Berberidaceae). It is biosynthesized from two molecules of coniferyl alcohol by phenolic oxidative coupling and a series of oxidations, reductions and methylations.

RuO4 is of specialized value in organic chemistry because it oxidizes virtually any hydrocarbon. For example, it will oxidize adamantane to 1-adamantanol. Because it is such an aggressive oxidant, reaction conditions must be mild, generally room temperature. Although a strong oxidant, RuO4 oxidations do not perturb stereocenters that are not oxidized.

" (pp. 5–6) Loeb addressed vitalism more explicitly: : "It is, therefore, unwarranted to continue the statement that in addition to the acceleration of oxidations the beginning of individual life is determined by the entrance of a metaphysical "life principle" into the egg; and that death is determined, aside from the cessation of oxidations, by the departure of this "principle" from the body. In the case of the evaporation of water we are satisfied with the explanation given by the kinetic theory of gases and do not demand that to repeat a well- known jest of Huxley the disappearance of the "aquosity" be also taken into consideration." (pp. 14–15) Bechtel states that vitalism "is often viewed as unfalsifiable, and therefore a pernicious metaphysical doctrine.

Trifluoroethanol is used as a solvent in organic chemistry. Oxidations of sulfur compounds using hydrogen peroxide are effectively conducted in TFE. It can also be used as a protein denaturant. In biology TFE is used as a co-solvent in protein folding studies with NMR spectroscopy: this solvent can effectively solubilize both peptides and proteins.

Juglone is derived by oxidation of the nontoxic hydrojuglone, 1,5-dihydroxynaphthalene, after enzymatic hydrolysis.Gerald Booth "Naphthalene Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley- VCH, Weinheim. . It can also be obtained by oxidations of 5,8-dihydroxy-1-tetralone with silver oxide (Ag2O), manganese dioxide (MnO2), or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ).

This is a plausible biosynthetic pathway, and intermediates 2, 3, 6, 7, and 8 have been identified using radio labeling studies. An alternative mechanism has been proposed with no hydroxyquinone intermediate (6). Rather, molecule 3 undergoes two subsequent oxidations at C-6 and C-7 to a structure resembling 8, then glycosylation to pseudopterosin.

In contrast to sulfoxides, the corresponding selenoxides are unstable in the presence of β-protons and this property is utilized in many organic reactions of selenium, notably in selenoxide oxidations and in selenoxide eliminations. Organoselenium compounds are found at trace levels in ambient waters, soils and sediments. The first organoselenium compound to be isolated was diethyl selenide in 1836.

Dox A is a cytochrome P-450 monooxygenase that has broad substrate specificity, catalyzing anthracycline hydroxylation at C-13 and C-14 ( Figure 2). The enzyme has an absolute requirement for molecular oxygen and NADPH. Initially, two successive oxidations are done at C-13, followed by a single oxidation of C-14 that converts daunorubicin to doxorubicin.

A β-lactam synthetase (ThnM) is thought to catalyze the formation of the β-lactam ring fused to the five-membered ring. How the cysteaminyl side-chain is incorporated is largely unknown, although ThnT, ThnR, and ThnH are involved in the processing of CoA to cysteamine for use in the pathway. Various oxidations complete the biosynthesis.

This is used in some organic chemistry oxidations, e.g. in the Fenton's reagent. Only catalytic quantities of iron ion is needed since peroxide also oxidizes ferrous to ferric ion. The net reaction of hydrogen peroxide and permanganate or manganese dioxide is manganous ion; however, until the peroxide is spent some manganese ions are reoxidized to make the reaction catalytic.

Oxidative stress in cells and tissues produces Free radical and singlet oxygen oxidations of linoleic acid to generate 13-HpODEs, 9-HpODEs, 13-HODEs, and 9-HODEs; these non-enzymatic reactions produce or are suspected but not proven to produce approximately equal amounts of their S and R stereoisomers. Free radical oxidations of linoleic acid also produce 13-EE- HODE, 9-hydroxy-10E,12-E-octadecadienoic acid, 9-hydroxy-10E,12-Z-octadecadienoic acid, and 11-hydroxy-9Z,12Z-octadecaenoic acid while singlet oxygen attacks on linoleic acid produce (presumably) racemic mixtures of 9-hydroxy-10E,12-Z-octadecadienoic acid, 10-hydroxy-8E,12Z-octadecadienoic acid, and 12-hydroxy-9Z-13-E-octadecadienoic acid. 4-Hydroxynonenal (i.e. 4-hydroxy-2E-nonenal or HNE) is also a peroxidation product of 13-HpODE.

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.

Further reactions, involving methyltransferase and oxygenase enzymes, yield the ergoline, lysergic acid. Lysergic acid (LA) is the substrate of lysergyl peptide synthetase, a nonribosomal peptide synthetase, which covalently links LA to the amino acids, L-alanine, L-proline, and L-phenylalanine. Enzyme- catalyzed or spontaneous cyclizations, oxygenations/oxidations, and isomerizations at selected residues precede, and give rise to, formation of ergotamine.

HClO may oxidise cysteines and methionines via their sulfhydryl groups and sulfur groups respectively. The former leads to the formation of disulfide bonds, inducing protein crosslinking. Both oxidations result in protein aggregation, and ultimately, cell death. Sulfhydryl groups can be oxidised up to three times by three HClO molecules, forming sulfenic acids, sulfinic acids and R–SO3H, which are increasingly irreversible and bactericidal.

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.

When describing electrochemical reactions an "E" and "C" formalism is often employed. The E represents an electron transfer; sometimes EO and ER are used to represent oxidations and reductions respectively. The C represents a chemical reaction which can be any elementary reaction step and is often called a "following" reaction. In coordination chemistry common C steps which "follow" electron transfer are ligand loss and association.

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.

Mitochondria from hearts suffering from a Plin5 deficiency had a membrana whose fatty acyl composition was altered, and its depolarization was compromised. It was also discovered in mice that, if a whole body deficiency of Plin5 was to happen, cardiac lipid droplet formation ability would be reduced, increasing fatty acid oxidations and promoting cardiac dysfunction. This, however, could be prevented by anti-oxidative therapy.

Medicinal Natural Products. John Wiley and Sons, LTD Multiple aldol additions occur to form four six-membered cyclization and aromization (2). The CLF/KS subunit is cleaved off by a thioesterase and modified by numerous steps (four oxidations, two NADPH dependent reductions, two methylations and decarboxylation) to form the final monomeric unit (3). Two monomer units undergo oxidative coupling to form the atropisomeric axis (4).

RuCl2(PPh3)3 facilitates oxidations, reductions, cross-couplings, cyclizations, and isomerization. It is used in the Kharasch addition of chlorocarbons to alkenes.Plummer, J. S.; Shun-Ichi, M.; Changjia, Z. "Dichlorotris(triphenylphosphine)ruthenium(II)", e-EROS Encyclopedia of Reagents for Organic Synthesis, 2010, John Wiley. :400px Dichlorotris(triphenylphosphine)ruthenium(II) serves as a precatalyst for the hydrogenation of alkenes, nitro compounds, ketones, carboxylic acids, and imines.

Thick oxides are usually grown with a long wet oxidation bracketed by short dry ones (a dry-wet-dry cycle). The beginning and ending dry oxidations produce films of high-quality oxide at the outer and inner surfaces of the oxide layer, respectively. Mobile metal ions can degrade performance of MOSFETs (sodium is of particular concern). However, chlorine can immobilize sodium by forming sodium chloride.

A generic oxaziridine derivative. An oxaziridine is an organic molecule that features a three-membered heterocycle containing oxygen, nitrogen, and carbon. In their largest application, oxaziridines are intermediates in the industrial production of hydrazine. Oxaziridine derivatives are also used as specialized reagents in organic chemistry for a variety of oxidations, including alpha hydroxylation of enolates, epoxidation and aziridination of olefins, and other heteroatom transfer reactions.

Once there is no oxide coating left on the mercury blob, the surface tension increases and the blob rounds up and loses contact with the nail, to start the process over again. The net reaction is that the dichromate oxidizes the iron. This favorable reaction drives the mercury oxidations/reductions and the oscillations in shape. When the dichromate is all reduced, the reaction stops.

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.

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.

The remarkable reactivity and substrate promiscuity of P450s have long attracted the attention of chemists. Recent progress towards realizing the potential of using P450s towards difficult oxidations have included: (i) eliminating the need for natural co-factors by replacing them with inexpensive peroxide containing molecules, (ii) exploring the compatibility of P450s with organic solvents, and (iii) the use of small, non- chiral auxiliaries to predictably direct P450 oxidation.

Some of the longest known and most widely used oxo compounds are oxidizing agents such as potassium permanganate (KMnO4) and osmium tetroxide (OsO4). Compounds such as these are widely used for converting alkenes to vicinal diols and alcohols to ketones or carboxylic acids. More selective or gentler oxidizing reagents include pyridinium chlorochromate (PCC) and pyridinium dichromate (PDC). Metal oxo species are capable of catalytic, including asymmetric oxidations of various types.

Methylrhenium trioxide serves as a heterogeneous catalyst for a variety of transformations. Supported on Al2O3/SiO2, it catalyzes olefin metathesis at 25 °C. In solution, MTO catalyses for the oxidations with hydrogen peroxide. Terminal alkynes yield the corresponding acid or ester, internal alkynes yield diketones, and alkenes give epoxides. MTO also catalyses the conversion of aldehydes and diazoalkanes into an alkene,Hudson, A. “Methyltrioxorhenium” Encyclopedia of Reagents for Organic Synthesis.

For the reaction to proceed efficiently, the alcohol must be at least partially dissolved in the aqueous solution. This can be facilitated by the addition of an organic co-solvent such as dioxane, pyridine, acetone or t-BuOH. KMnO4 will readily react with a carbon-carbon double bond before oxidizing a primary alcohol. Normally, these oxidations are performed under strong basic conditions, because this promotes a greater oxidation speed and selectivity.

Compounds of chromium(V) are rather rare; the oxidation state +5 is only realized in few compounds but are intermediates in many reactions involving oxidations by chromate. The only binary compound is the volatile chromium(V) fluoride (CrF5). This red solid has a melting point of 30 °C and a boiling point of 117 °C. It can be prepared by treating chromium metal with fluorine at 400 °C and 200 bar pressure.

One of the major pitfalls of either the Fleming or Tamao oxidations is steric hindrance. Increasing the steric bulk at the silicon center generally slows down reaction, potentially even suppressing reaction entirely when certain substituents are employed. In general, less bulky groups such as methyl or ethyl favor oxidation, while bulkier groups such as tert-butyl slow down or stop oxidation. There are special cases in which this pattern in not followed.

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.

For a comprehensive coverage of the subject see Micro Process Engineering. Examples for reactions that have worked in microreactors include aromatics oxidations, diazomethane conversions, Grignards, halogenations, hydrogenations, nitrations, and Suzuki couplings. According to experts in the field, 70% of all chemical reactions could be done in microreactors, however only 10-15% are economically justified. With the exception of some stereospecific reactions, particularly biotechnology, mastering these technologies does not represent a distinct competitive advantage.

The field of molecular mechanics, as it is now known, has wide applications. In 1943, Westheimer began publishing on the mechanisms of chromic acid oxidations, publishing a "masterly review" of the area in 1949. In 1950, University of Chicago biochemist Birgit Vennesland approached Vennesland about a project she and her student Harvey Fisher were doing, involving isotopes in enzyme reactions. Vennesland had developed a project involving the fate of hydrogen atoms in alcohol dehydrogenase.

The is that the radical becomes effectively neutralized, while the antioxidant itself becomes a radical. Antioxidants, however, are much less reactive radicals as they are usually rather large and resonance stabilized aromatic compounds, and therefore prevent undesired oxidations from occurring. The addition of antioxidants in the reaction mixture in this experiment would effectively quench the peroxide radicals, and therefore the reaction would then proceed to form (mainly) the 1,2 –dibromopropane product, as was observed.

Unlike mammals, yeast (Saccharomyces cerevisiae) do not have several isoforms of FMO, but instead only have one called yFMO. This enzyme does not accept xenobiotic compounds. Instead, yFMO helps to fold proteins that contain disulfide bonds by catalyzing O2 and NADPH-dependent oxidations of biological thiols, just like mammalian FMO's. An example is the oxidation of glutathione to glutathione disulfide, both of which form a redox buffering system in the cell between the endoplasmic reticulum and the cytoplasm.

Oxidation of methane to , which requires reactions with the OH radical, produces an instantaneous reduction in radiative absorption and emission since is a weaker greenhouse gas than methane. However, the oxidations of CO and are entwined since both consume OH radicals. In any case, the calculation of the total radiative effect includes both direct and indirect forcing. A second type of indirect effect happens when chemical reactions in the atmosphere involving these gases change the concentrations of greenhouse gases.

Referred to as asymmetric depletion, a negative non-linear effect is present when the eeproduct is lower than predicted by an ideal linear situation. In contrast to a (+)-NLE, a (−)-NLE results in a faster overall reaction rate and a decrease in enantioselectivity. Synthetically, a (−)-NLE effect could be beneficial with a reasonable assay for separating product enantiomers and a high output is necessary . An interesting example of a (−)-NLE effect has been reported in asymmetric sulfide oxidations.

Its biosynthesis starts from the fatty acid linolenic acid, which is oxygenated by Lipoxygenase (13-LOX), forming a peroxide. This peroxide then cyclizes in the presence of allene oxide synthase to form an allene oxide. This allene oxide rearranges as it gets catalyzed by the enzyme allene oxide cyclase to form 12-oxophytodienoic acid, and undergoes a series of β-oxidations to 7-iso-jasmonic acid. In the absence of enzyme, this iso- jasmonic acid isomerizes to jasmonic acid.

The tungsten oxidoreductases may also catalyse oxidations. The first tungsten-requiring enzyme to be discovered also requires selenium, and in this case the tungsten- selenium pair may function analogously to the molybdenum-sulfur pairing of some molybdopterin-requiring enzymes. One of the enzymes in the oxidoreductase family which sometimes employ tungsten (bacterial formate dehydrogenase H) is known to use a selenium-molybdenum version of molybdopterin. Acetylene hydratase is an unusual metalloenzyme in that it catalyzes a hydration reaction.

Oxidative stress in cells and tissues produces Free- radical-induced and singlet-oxygen-induced oxidations of linoleic acid to generate the various racemic mixtures of 9-HpODE and 9-HODE in non-enzymatic reactions that produce, or are suspected but not proven to produce, approximately equal amounts of their S and R stereoisomers.Prog Lipid Res. 1984;23(4):197-221Biochim Biophys Acta. 1998 May 20;1392(1):23-40Chem Res Toxicol. 2005 Feb;18(2):349-56 These oxidations are credited with being the major contributors to 9-HODE and 13-HODE isomer production in tissues undergoing oxidative stress such as occurs in any tissue suffering inadequate blood flow, inflammation, or other serious insult, in liver steatohepatitis, in the atheroma plaques of cardiovascular disease, in nerve tissues of neurodegenerative diseases, and in the various tissues compromised by diabetes (see oxidative stress). Free-radical oxidation of linoleic acid produces racemic mixtures of 9-HODE and 9-EE-HODE; singlet-oxygen attack on linoleic acid produces (presumably) racemic mixtures of 9-HODE, 10-hydroxy-8E,12Z-octadecadienoic acid, and 12-hydroxy-9Z-13-E-octadecadienoic acid.

The conversion of 2× 2Carbon glycine to 1 C3 serine in the mitochondria by the enzyme glycine-decarboxylase is a key step, which releases , NH3, and reduces NAD to NADH. Thus, 1 molecule is produced for every 2 molecules of (two deriving from RuBisCO and one from peroxisomal oxidations). The assimilation of NH3 occurs via the GS-GOGAT cycle, at a cost of one ATP and one NADPH. Cyanobacteria have three possible pathways through which they can metabolise 2-phosphoglycolate.

He shared half of the Nobel Prize in Chemistry in 2001 with Ryōji Noyori for "their work on chirally catalysed hydrogenation reactions". The other half of the prize was awarded to K. Barry Sharpless for the development of a range of catalytic asymmetric oxidations. Knowles developed one of the first asymmetric hydrogenation catalysts by replacing the achiral triphenylphosphine ligands in Wilkinson's catalyst with chiral phosphine ligands. This experimental catalyst was effective for enantioselective synthesis, achieving a modest 15% enantiomeric excess.

All these incidents were classified at the lowest level on the International Nuclear Event Scale, and none of the events prevented restarting operation of the facility after repairs. As of 1997, there had been 27 sodium leaks, 14 of which resulted in sodium-air oxidations/"fires". The steam generators are separated in modules so they can be repaired without shutting down the reactor. As of 2020, the cumulative "energy Availability factor" calculated up to year 2019 and recorded by the IAEA was 75.6%.

Photodegradation of a plastic bucket used as an open- air flowerpot for some years Many organic chemicals are thermodynamically unstable in the presence of oxygen; however, their rate of spontaneous oxidation is slow at room temperature. In the language of physical chemistry, such reactions are kinetically limited. This kinetic stability allows the accumulation of complex environmental structures in the environment. Upon the absorption of light, triplet oxygen converts to singlet oxygen, a highly reactive form of the gas, which effects spin-allowed oxidations.

Furthermore, the carboxylic acid moiety is a common feature of natural products and can also be prepared by relatively benign air oxidations. Additional benefits include the broad tolerance of functional groups, as well as the capacity to avoid the use of strong bases. An important elementary step in this reaction is protodecarboxylation or metalation to first convert the C–COOH bond to a C–H or C–M bond respectively. Shang R, Liu, L. Transition metal-catalyzed decarboxylative cross-coupling reactions.

This heightened reactivity has many practical consequences. The industrial production of acrylonitrile by ammoxidation of propene exploits the easy oxidation of the allylic C−H centers: :2CH3−CH=CH2 \+ 2NH3 \+ 3O2 → 2CH2=CH−C≡N + 6H2O Unsaturated fats spoil by rancidification involving attack at allylic C−H centers. Benzylic and allylic are related in terms of structure, bond strength, and reactivity. Other reactions that tend to occur with allylic compounds are allylic oxidations, ene reactions, and the Tsuji–Trost reaction.

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.

Trifluoroperacetic acid (trifluoroperoxyacetic acid, TFPAA) is an organofluorine compound, the peroxy acid analog of trifluoroacetic acid, with the condensed structural formula . It is a strong oxidizing agent for organic oxidation reactions, such as in Baeyer–Villiger oxidations of ketones. It is the most reactive of the organic peroxy acids, allowing it to successfully oxidise relatively unreactive alkenes to epoxides where other peroxy acids are ineffective. It can also oxidise the chalcogens in some functional groups, such as by transforming selenoethers to selones.

Aminoxyl radicals are chemical species containing the R2N–O• functional group. They are also known as nitroxyl radicals and nitroxides, however IUPAC discourages the use of these terms, as they erroneously suggest the presence of a nitro group. They are radicals and are structurally related to hydroxylamines and N-oxoammonium salts, with which they can interconvert via a series of redox steps. center Sterically hindered aminoxyls such TEMPO and TEMPOL and are persistent (stable) radicals and find use in a range of oxoammonium-catalyzed oxidations.

A peroxidase enzyme known as MroAPO (Marasmius rotula aromatic peroxygenase) is attracting research interest for possible applications in biocatalysis. In general, enzymes that catalyze oxygen- transfer reactions are of great utility in chemical synthesis since they work selectively and under ambient conditions. Fungal peroxidases can catalyze oxidations that are difficult for the organic chemist, including those involving aromatic substrates such as aniline, 4-aminophenol, hydroquinone, resorcinol, catechol, and paracetamol. The M. rotula enzyme is the first fungal peroxygenase that can be produced in high yields.

In the morphine biosynthetic pathway, salutaridinol is derived in three steps from (R)-reticuline. First, (R)-reticuline undergoes an oxidation at each of its phenol rings mediated by the cytochrome P-450-dependent monooxygenase salutaridine synthase. These phenol group oxidations yield a diradical species that undergoes ortho coupling to the phenol group of the tetrahydroisoquinoline and para coupling to the benzyl group to create the salutaridinol precursor salutaridine. A stereospecific reduction of the salutaridine carbonyl group by salutaridine: NADPH 7-oxidoreductase then generates salutaridinol.

The active species in these catalysts were identified to be hemispherical gold nano-crystals of less than 2 nm in diameter in intimate contact with the support. Alkene epoxidation has been demonstrated in absence of H2 reuductant in the liquid phase. For example, using 1% Au/graphite, ~80% selectivities of cis-cyclooctene to cyclooctene oxide (analogous to cyclohexene oxide) were obtained at 7-8% conversion, 353 K (80 °C), and 3 MPa O2 in absence of hydrogen or solvent. Other liquid-phase selective oxidations have been achieved with saturated hydrocarbons.

Franklin Arnold Davis (born April 1, 1939) is the Laura H. Carnell Professor of Chemistry at Temple University in Philadelphia, Pennsylvania. He is most notable for his development of sulfur-nitrogen reagents including N-sulfonyloxaziridine for oxidations and asymmetric hydroxylations and N-sulfinyl imines for the asymmetric synthesis of chiral amine derivatives. The reagents are commonly called Davis oxaziridines and Davis sulfinamides, respectively. Honors and awards include the American Chemical Society Arthur C. Cope Scholar Award (2006)Arthur C. Cope Scholar Awards and the John Scott Medal (2006).

TEMPO oxidations also exhibit chemoselectivity, being inert towards secondary alcohols, but the reagent will convert aldehydes to carboxylic acids. In cases where secondary oxidizing agents cause side reactions, it is possible to stoichiometrically convert TEMPO to the oxoammonium salt in a separate step. For example, in the oxidation of geraniol to geranial, 4-acetamido-TEMPO is first oxidized to the oxoammonium tetrafluoroborate. TEMPO can also be employed in nitroxide-mediated radical polymerization (NMP), a controlled free radical polymerization technique that allows better control over the final molecular weight distribution.

It is also useful in dehydrohalogenation reactions and Swern oxidations. Triethylamine is readily alkylated to give the corresponding quaternary ammonium salt: :RI + Et3N -> Et3NR+I− Triethylamine is mainly used in the production of quaternary ammonium compounds for textile auxiliaries and quaternary ammonium salts of dyes. It is also a catalyst and acid neutralizer for condensation reactions and is useful as an intermediate for manufacturing medicines, pesticides and other chemicals. Triethylamine salts like any other tertiary ammonium salts are used as an ion-interaction reagent in ion interaction chromatography, due to their amphiphilic properties.

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.

In work undertaken in collaboration with Arthur F. Ferris, Emmons reported that in situ generated trifluoroperacetic acid was capable of oxidising aniline to nitrobenzene, an observation which pioneered the applications of this peroxy acid as an oxidising agent in organic chemistry. Emmons went on to discuss the preparation of trifluoroperacetic acid and numerous applications of the new reagent, including: oxidation of nitrosamines to nitramines; the Baeyer–Villiger oxidations of ketones to esters; and the conversion of alkenes to epoxides (in the presence of a buffer) or to glycols (without the buffer).

Individual polyphenols engage in reactions related to both their core phenolic structures, their linkages, and types of glycosides they form. Standard phenolic reactions include ionization (which contributes to solubility and complexation), oxidations to ortho- and para-quinones (which contributes to antioxidant characteristics), and underlying aromatic transformations related to the presence of the phenolic hydroxyl (see phenol image above); reactions related to their linkages include nucleophilic additions, and oxidative and hydrolytic bond cleavages. In addition, as noted above, a traditional feature of polyphenols was their ability to form particular, characteristic metal complexes.

Telluric acid is formed by the oxidation of tellurium or tellurium dioxide with a powerful oxidising agent such as hydrogen peroxide, chromium trioxide or sodium peroxide. :TeO2 \+ H2O2 \+ 2 H2O → Te(OH)6 Crystallization of telluric acid solutions below 10 °C gives Te(OH)6·4H2O. It is oxidizing, as shown by the electrode potential for the reaction below, although it is kinetically slow in its oxidations. :H6TeO6 \+ 2 H+ \+ 2 e− ⇌ TeO2 \+ 4 H2O E ~~o~~ = +1.02 V Chlorine, by comparison, is +1.36 V and selenous acid is +0.74 V in oxidizing conditions.

The presence of an aromatic ring, a ketone and a γ-lactam moiety, gives to isatin the rare potential to be used as both an electrophile and a nucleophile: indeed, it undergoes an enormous number of reactions, such as N-substitutions, electrophilic aromatic substitution at positions C-5 and C-7 of the phenyl ring, nucleophilic additions onto the C-3 carbonyl group, chemoselective reductions, oxidations, ring-expansions and spiro-annulations. Because of this unique reactivity, isatin is considered one of the most valuable building blocks in organic synthesis.

There is some information on serum vitamin C concentrations maintained in animal species that are able to synthesize vitamin C. One study of several breeds of dogs reported an average of 35.9 μmol/L. A report on goats, sheep and cattle reported ranges of 100–110, 265-270 and 160-350 μmol/L, respectively. Vitamin C biosynthesis in vertebrates The biosynthesis of ascorbic acid in vertebrates starts with the formation of UDP-glucuronic acid. UDP-glucuronic acid is formed when UDP-glucose undergoes two oxidations catalyzed by the enzyme UDP- glucose 6-dehydrogenase.

Oxovanadium(V) also forms 7 coordinate coordination complexes with tetradentate ligands and peroxides and these complexes are used for oxidative brominations and thioether oxidations. The coordination chemistry of V4+ is dominated by the vanadyl center, VO2+, which binds four other ligands strongly and one weakly (the one trans to the vanadyl center). An example is vanadyl acetylacetonate (V(O)(O2C5H7)2). In this complex, the vanadium is 5-coordinate, square pyramidal, meaning that a sixth ligand, such as pyridine, may be attached, though the association constant of this process is small.

This cyclase enzyme has been identified as a key enzyme in forming the carbon skeleton of pseudopterosins in one step. An alternative mechanism has been proposed in which a six-membered ring is formed first, then a second ring closing for the bicyclic system. GPP cyclization to elisabethatriene The biosynthesis of the pseudopterosins continues with an aromatization to erogorgiaene (3), two oxidations to a dihyroxyerogorgiaene (4, then 5), and another oxidation to an ortho-hydroxyquinone (6). Ring closure (7), re-aromatization to (8) and glycosylation yield Pseudopterosin A (9).

Mixed-function oxidase is the name of a family of oxidase enzymes that catalyze a reaction in which each of the two atoms of oxygen in O2 is used for a different function in the reaction. Oxidase is a general name for enzymes that catalyze oxidations in which molecular oxygen is the electron acceptor but oxygen atoms do not appear in the oxidized product. Often, oxygen is reduced to either water (cytochrome oxidase of the mitochondrial electron transfer chain) or hydrogen peroxide (dehydrogenation of fatty acyl-CoA in peroxisomes). Most of the oxidases are flavoproteins.

Typically, manganese ores are purified by their conversion to manganese(II) sulfate. Treatment of aqueous solutions of the sulfate with sodium carbonate leads to precipitation of manganese carbonate, which can be calcined to give the oxides MnOx. In the laboratory, manganese sulfate can be made by treating manganese dioxide with sulfur dioxide: :MnO2 \+ SO2 \+ H2O → MnSO4(H2O) It can also be made by mixing potassium permanganate with sodium bisulfate and hydrogen peroxide. Manganese sulfate is a by-product of various industrially significant oxidations that use manganese dioxide, including the manufacture of hydroquinone and anisaldehyde.

Oxoammonium cations are isoelectronic with carbonyls and structurally related to aldoximes (hydroxylamines), and aminoxyl (nitroxide) radicals, with which they can interconvert via a series of redox steps. According to X-ray crystallography, the N-O distance in [TEMPO]BF4 is 1.184 Å, 0.1 Å shorter than the N-O distance of 1.284 Å in the charge-neutral TEMPO. Similarly, the N in [TEMPO]+ is nearly planar, but the O moves 0.1765 Å out of the plane in the neutral TEMPO. center The N-oxoammonium salts are used for oxidation of alcohols to carbonyl groups, as well as other forms of oxoammonium-catalyzed oxidations.

Professor Hill’s research encompasses fundamental structural and reactivity studies, Catalysis, functional nanomaterials (Nanotechnology), antiviral chemotherapy and solar energy conversion (Artificial Photosynthesis). The principal systems he studies are inorganic cluster molecules, particularly transition metal oxygen anion clusters or polyoxometalates. The general theme of his research is the design and realization of highly complex structures to facilitate one or more intellectually challenging and/or societally important tasks. Craig L. Hill’s achievements include the development of polyoxometalate photochemistry and polyoxometalate-based catalysts for the functionalization of C-H bonds Carbon-hydrogen bond activation and very fast air-based oxidations (for decontamination, remediation, chemical transformations).

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.

For example, the ethyl mercaptan (ethanethiol) has the formula C2H5SH. The second step is referred to as regeneration and it involves heating and oxidizing of the caustic solution leaving the extractor. The oxidations results in converting the extracted mercaptans to organic disulfides (RSSR) which are liquids that are water- insoluble and are then separated and decanted from the aqueous caustic solution. The reaction that takes place in the regeneration step is: :4NaSR + O2 \+ 2H2O → 2RSSR + 4NaOH After decantation of the disulfides, the regenerated "lean" caustic solution is recirculated back to the top of the extractor to continue extracting mercaptans.

Heterogeneous catalysis has the catalyst in a different phase from the reactants. Heterogeneous photocatalysis is a discipline which includes a large variety of reactions: mild or total oxidations, dehydrogenation, hydrogen transfer, 18O2–16O2 and deuterium-alkane isotopic exchange, metal deposition, water detoxification, gaseous pollutant removal, etc. Most common heterogeneous photocatalysts are transition metal oxides and semiconductors, which have unique characteristics. Unlike the metals which have a continuum of electronic states, semiconductors possess a void energy region where no energy levels are available to promote recombination of an electron and hole produced by photoactivation in the solid.

In Complex III (cytochrome bc1 complex or CoQH2-cytochrome c reductase; ), the Q-cycle contributes to the proton gradient by an asymmetric absorption/release of protons. Two electrons are removed from QH2 at the QO site and sequentially transferred to two molecules of cytochrome c, a water-soluble electron carrier located within the intermembrane space. The two other electrons sequentially pass across the protein to the Qi site where the quinone part of ubiquinone is reduced to quinol. A proton gradient is formed by one quinol (2H+2e-) oxidations at the Qo site to form one quinone (2H+2e-) at the Qi site.

It was envisaged that Taxol (51) could be accessed through tail addition of the Ojima lactam 48 to alcohol 47. Of the four rings of Taxol, the D ring was formed last, the result of a simple intramolecular SN2 reaction of hydroxytosylate 38, which could be synthesized from hydroxyketone 27. Formation of the six-membered C ring took place through a Dieckmann condensation of lactone 23, which could be obtained through a Chan rearrangement of carbonate ester 15. Substrate 15 could be derived from ketone 6, which, after several oxidations and rearrangements, could be furnished from commercially available patchoulene oxide 1.

Directed by Marco Gallo and produced by SINGLE FILMS : NICOLAS STOPPA-HARIS DONIAS. February 2018 finalist with the trailer of the film "rossotrevi twice in history" al Barcelona planet film festival March 2018 finalist with the trailer of the film "rossotrevi twice in history" al Bucharest short cine festival April 2018 finalist with the trailer of the film "rossotrevi twice in history" al Los Angeles The Independent Cinema Showcase! May 2018 winner of the first prize at the Kalat Nissa Film Festival (Caltanissetta) with the trailer of the fim "Rossotrevi twice in history". directed by Marco Gallo August 2018 "Oxidations" exhibition at Palazzo Tursi Genoa Italy photos on steel Ilva plates.

Site-directed mutagenesis of the potential acid/base residues in the active site did not affect catalysis leading to the conclusion that Dnr K most likely acts as an entropic enzyme in that rate enhancement is mainly due to orientational and proximity effects. This is in contrast to most other O-methyltransferases where acid/base catalysis has been demonstrated to be an essential contribution to rate enhancement. Dox A catalyzes three successive oxidations in streptomyces peucetius. Deficient DXR production is not primarily due to low levels of or malfunctioning Dox A, but because there are many products diverted away from the pathway shown in Figure 2.

The 5 methyl groups are added via S-adenosyl methionine (SAM) methylation, as opposed to incorporation of propionate (instead of acetate) to the growing compound during biosynthesis. The following internal cyclization proceeds through a Diels–Alder reaction catalyzed by an unknown enzyme. The origin of the subsequent oxidations at positions 1, 2 and 8 have yet to be characterized, but they have been shown not to originate from acetate. It has been theorized that cytochrome P-450 is responsible for the oxidation at these three positions since its inhibition produces probetaenone 1, the non-oxidized form of betaenone B. Biosynthesis of betaenone B as proposed by Oikawa et al.

Biosynthetic pathway Biosynthesis of mevastatin is primarily accomplished via a type 1 PKS pathway it proceeds in the PKS pathway as seen in figure 1 until it reaches a hexaketide state where it undergoes a Diels- Alder cyclization. After cyclization it continues via the PKS pathway to a nonaketide after which it is released and undergoes oxidation and dehydration. It is presumed that the oxidations are preformed by a polypeptide that is similar to cytochrome p450 monooxygenase, which is encoded by mlcC within the mevastatin gene. Lastly the biosynthesis is completed by the PKS facilitating the addition of a diketide sidechain and a methylation by SAM.

After a cytosine is methylated to 5mC, it can be reversed back to its initial state via multiple mechanisms. Passive DNA demethylation by dilution eliminates the mark gradually through replication by a lack of maintenance by DNMT. In active DNA demethylation, a series of oxidations converts it to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC), and the latter two are eventually excised by thymine DNA glycosylase (TDG), followed by base excision repair (BER) to restore the cytosine. TDG knockout produced a 2-fold increase of 5fC without any statistically significant change to levels of 5hmC, indicating 5mC must be iteratively oxidized at least twice before its full demethylation.

Tolman's work in the bioinorganic field focuses on Cu-O adducts, specifically copper proteins whose diverse, biological functions include: O2 transport, aromatic ring oxidations, biogenesis of hormones. His work studies the potential of 1:1 Cu/O2 adducts as catalytic species, which have been known as transient intermediates for more commonly studied 2:1 and even 3:1 Cu/O2 molecules. These complexes, while kinetically favored in formation are thermodynamically unstable due to negative entropy values, thus making them more difficult to isolate. Although, increasing ligand sizes on these 1:1 adducts did correlate with slower reaction rate constants; advantageous for isolating and studying these complexes.

DNA repair is the process by which all living cells deal with damage to their genetic material. Such damage occurs as a consequence of exposure to environmental radiations and genotoxic chemicals, but also to endogenous oxidations and the intrinsic instability of DNA. Hanawalt and his colleagues discovered a special pathway of excision repair, called transcription-coupled repair, which is targeted to expressed genes, and he studies several diseases characterized by defects in DNA repair pathways. DNA repair is important for protecting against cancer and some aspects of ageing in humans, and its deficiency has been implicated in the etiology of a number of hereditary diseases.

Prior to the commercialization of the Monsanto process, most acetic acid was produced by oxidation of acetaldehyde. This remains the second-most-important manufacturing method, although it is usually not competitive with the carbonylation of methanol. The acetaldehyde can be produced by hydration of acetylene. This was the dominant technology in the early 1900s. Light naphtha components are readily oxidized by oxygen or even air to give peroxides, which decompose to produce acetic acid according to the chemical equation, illustrated with butane: : 2 C4H10 \+ 5 O2 → 4 CH3CO2H + 2 H2O Such oxidations require metal catalyst, such as the naphthenate salts of manganese, cobalt, and chromium.

Novel or enhanced synthetic techniques can often provide improved environmental performance or enable better adherence to the principles of green chemistry. For example, the 2005 Nobel Prize for Chemistry was awarded to Yves Chauvin, Robert H. Grubbs and Richard R. Schrock, for the development of the metathesis method in organic synthesis, with explicit reference to its contribution to green chemistry and "smarter production." A 2005 review identified three key developments in green chemistry in the field of organic synthesis: use of supercritical carbon dioxide as green solvent, aqueous hydrogen peroxide for clean oxidations and the use of hydrogen in asymmetric synthesis. Some further examples of applied green chemistry are supercritical water oxidation, on water reactions, and dry media reactions.

All oxidations were performed at 1200 °C in steam for 75 minutes. Figure 1 (a) shows oxidation- induced stacking faults in <100>-oriented wafers after 30 minutes Wright etch, (b) and (c) show dislocation pits on <100>- and <111>-oriented wafers respectively after 20 minutes Wright etch. Figure 1 (a),(b),(c) Figure 1 (a) shows oxidation-induced stacking faults on a <100>-oriented, 7-10 Ω-cm, boron- doped wafer after 30 minutes Wright etch (the A arrow in this figure points to the shape of faults that intersect the surface, while B points to bulk faults). Figure 1 (b) and (c) show dislocation pits on <100>- and <111>-oriented wafers respectively after 20 minutes Wright etch.

A chromate ester is a chemical structure that contains a chromium atom (symbol Cr) in a +6 oxidation state that is connected via an oxygen (O) linkage to a carbon (C) atom. The Cr itself is in its chromate form, with several oxygens attached, and the Cr–O–C attachment makes this chemical group structurally similar to other ester functional groups. They can be synthesized from various chromium(VI) metal compounds, such as CrO3, chromium chloride complexes, and aqueous chromate ions, and tend to react via redox reactions to liberate chromium(IV). Chromate esters are the key reactive intermediates in the Jones oxidation, the mechanistically related oxidations using pyridinium dichromate or pyridinium chlorochromate.

An indolic acid moiety modified from L-tryptophan is then ligated to the unmodified cysteine residue through a thioester linkage. After methylation and oxidation of the indole, the second macrocycle is formed by reaction of the indole hydroxyl group with the free carboxyl group of the nearby glutamate residue. The now fused bicyclic peptide undergoes several oxidations and partial cleavage of the C-terminal dehydroalanine residue to give the mature nosiheptide. Amino acid dehydration of residues in nosiheptideNosiheptide intermediate diels-alder type cyclization and aromatization The translation and modification of the precursor peptide is undertaken by several enzymes encoded in a localized gene cluster containing 14 structural genes and 1 regulatory gene.

Methanotrophs are a specific type of methylotroph that are also able to use methane () as a carbon source by oxidizing it sequentially to methanol (), formaldehyde (), formate (), and carbon dioxide initially using the enzyme methane monooxygenase. As oxygen is required for this process, all (conventional) methanotrophs are obligate aerobes. Reducing power in the form of quinones and NADH is produced during these oxidations to produce a proton motive force and therefore ATP generation. Methylotrophs and methanotrophs are not considered as autotrophic, because they are able to incorporate some of the oxidized methane (or other metabolites) into cellular carbon before it is completely oxidized to (at the level of formaldehyde), using either the serine pathway (Methylosinus, Methylocystis) or the ribulose monophosphate pathway (Methylococcus), depending on the species of methylotroph.

In addition to simple oxidation of aromatic rings to form carbonyl compounds (see ), trifluoroperacetic acid can fully cleave the carbon–carbon bonds within the ring. Unlike other oxidations of alkylaromatic structures, which yield benzoic acids and related compounds by cleavage of the alkyl chain at the reactive benzylic position, trifluoroperacetic acid causes an "inverse oxidation", cleaving the aromatic ring itself while leaving the alkyl group intact. 350px This selectivity for certain types of bonds allows it to be used to decompose complex mixtures of hydrocarbonds, such as coal, in order to determine structural details. Aromatic systems containing heteroatoms are resistant to this ring-opening as heteroatom oxidation occurs preferentially and deactivates the ring towards electrophilic attack by the peroxy acid.

Since free-radical-induced and singlet-oxygen-induced oxidations of linoleic acid produce a similar set of 13-HODE metabolites (see 13-Hydroxyoctadecadienoic acid), since both free radicals and singlet oxygen attack not only free linoleic acid but also linoleic acid bound to phospholipids, glycerides, cholesterol, and other lipids, and since free- radical and singlet-oxygen reactions may occur together, oxygen-stressed tissues often contain an array of free and lipid-bound 9-HODE and 13-HODE products. For example, laboratory studies find that 9-HODE and 9-EE-HODE (along with their 13-HODE counterparts) are found in the phospholipid and cholesterol components of low-density lipoproteins that have been oxidized by human monocytes; the reaction appears due to the in situ free-radical- and/or superoxide-induced oxidation of the lipoproteins.

IBX is also available as silica gel or polystyrene bound IBX. In many applications, IBX is replaced by Dess–Martin periodinane which is more soluble in common organic solvents. A sample reaction is an IBX oxidation used in the total synthesis of eicosanoid: More and Finney and Van Arman have demonstrated that common organic solvents are suitable for many IBX oxidations, despite its low solubility, and in fact may simplify product purification. :IBX oxidation of alcohol to aldehyde key data: a) IBX, DMSO, THF, 4h, 94% chemical yield (Mohapatra, 2005) In 2001, K. C. Nicolaou and co- workers published a series of papers in the Journal of the American Chemical Society demonstrating, among other transformations, the use of IBX to oxidize primary and secondary benzylic carbons to aromatic aldehydes and ketones, respectively.

Since 1992 he has continued to work in the laboratory on various problems, mostly in oxidation chemistry.Nicholas E. Leadbeater, James M. Bobbitt: TEMPO-Derived Oxoammonium Salts as Versatile Oxidizing Agents, Aldrichimica Acta 47 (2014), S. 65−74. In 1959, he received a National Science Foundation Fellowship to work with at the University of Zürich in Switzerland on iridoid glycosides. Bobbitt also worked as a visiting lecturer; from 1964 to 1965 at the University of East Anglia under the direction of Alan R. Katritzky; in June 1968 with a short DAAD grant at the University of Kiel with Burchard Franck; from 1971 to 1990 in a collaboration with Tohoku University in Sendai, Japan with Tetsuji Kametani and Tetsuo Osa on catalytic oxidations; and at La Trobe University in Australia from 1980 to 1981 and at the University of Adelaide in 1985.

Barrett has invented many reactions including novel glycosidations, atom-economic aromatic substitution reactions, metal-catalyzed oxidations and hydroaminations, reactions using ROMP-gel supported reagents and multi-component benzyne coupling reactions. He has contributed extensively to the synthesis of β-lactams using alkenyl anions, ynolates, novel isocyanates, iron vinylidines, heteroatom functionalized nitroalkenes, and ring closing alkene and enyne metathesis reactions. He has completed the total synthesis of diverse bioactive natural products including papulacandin D, papuamine, showdomycin, milbemycin β3, the palmarumycins and preussomerin G, (+)-calyculin A and the multiple cyclopropane CETP inhibitor U-106305 and structurally related cyclopropane nucleoside FR-900848 and coronanes. He has also published highly flexible methods for the biomimetic total syntheses of resorcylate and meroterpenoid natural products including 15G256β, aigialomycin D, LL-Z1640-2, cruentaren A, hericenone J and macrosporin, amorphastilbol, (+)-hongoquercin A and B, and austalides.

Space-filling model of pyrene showing the planar structure Pyrene is a polycyclic aromatic hydrocarbon consisting of four benzene rings fused together in a planar aromatic arrangement which approximates a rhombus in shape. Benzo[a]pyrene is a derivative in which a fifth benzene ring has been fused to the pyrene system, and is a component of tobacco smoke which is a procarcinogen partly responsible for the carcinogenic and mutagenic effects of smoking. Benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide is a metabolite of benzo[a]pyrene formed by the introduction of vicinal hydroxyl and epoxide functional groups to the fifth benzene ring. These oxidations are stereoselective, producing the pair of enantiomers with the hydroxyl groups on opposite sides of the pyrene plane and with the epoxide on the same side as its adjacent hydroxyl group.

He co-developed the Direct Methanol Fuel Cell (DMFC) with collaborators from NASA-JPL. He introduced and developed trifluoromethyltrimethylsilane as a trifluoromethylating reagent in organic chemistry and it is sometimes referred to as the Ruppert-Prakash reagent. His group's current research interests cover a wide range of subjects in the area of selective fluorinations, fluoroalkylations, oxidations, energetic materials, reductions, stereoselective reactions, electrochemical synthesis, hydrocarbon activation and isomerization, anthropogenic CO2 based fuels and feed-stocks, direct oxidation fuel cells, lithium ion battery electrolytes, iron batteries, flow batteries, electrochemistry, polymer chemistry, superacid catalyzed reactions, stable carbocation chemistry, application of ab initio and DFT theory and NMR chemical shift calculations. His coauthored book with G. A.Olah and A. Goeppert on solving the carbon conundrum, Beyond Oil and Gas: The Methanol Economy (translated into Chinese, Swedish, Hungarian, Japanese and Russian), Wiley VCH (published in three editions, 2006, 2009 and 2018) is getting increasing attention and adoption world-wide.

GAs are usually synthesized from the methylerythritol phosphate (MEP) pathway in higher plants. In this pathway, bioactive GA is produced from trans- geranylgeranyl diphosphate (GGDP). In the MEP pathway, three classes of enzymes are used to yield GA from GGDP: terpene syntheses (TPSs), cytochrome P450 monooxygenases (P450s), and 2-oxoglutarate–dependent dioxygenases (2ODDs). There are eight steps in the MEP pathway: # GGDP is converted to ent- copalyl diphosphate (ent-CPD) by ent-copalyl diphosphate synthase # etn-CDP is converted to ent-kaurene by ent-kaurene synthase # ent-kaurene is converted to ent-kaurenol by ent-kaurene oxidase (KO) # ent-kaurenol is converted to ent- kaurenal by KO # ent-kaurenal is converted to ent-kaurenoic acid by KO # ent- kaurenoic acid is converted to ent-7a-hydroxykaurenoic acid by ent-kaurene acid oxidase (KAO) # ent-7a-hydroxykaurenoic acid is converted to GA12-aldehyde by KAO # GA12-aldehyde is converted to GA12 by KAO. GA12 is processed to the bioactive GA4 by oxidations on C-20 and C-3, which is accomplished by 2 soluble ODDs: GA 20-oxidase and GA 3-oxidase.

Vanadium(V) oxide is a catalyst in the contact process for producing sulfuric acid Vanadium compounds are used extensively as catalysts; Vanadium pentoxide V2O5, is used as a catalyst in manufacturing sulfuric acid by the contact process In this process sulfur dioxide () is oxidized to the trioxide (): In this redox reaction, sulfur is oxidized from +4 to +6, and vanadium is reduced from +5 to +4: :V2O5 \+ SO2 → 2 VO2 \+ SO3 The catalyst is regenerated by oxidation with air: :4 VO2 \+ O2 → 2 V2O5 Similar oxidations are used in the production of maleic anhydride: :C4H10 \+ 3.5 O2 → C4H2O3 \+ 4 H2O Phthalic anhydride and several other bulk organic compounds are produced similarly. These green chemistry processes convert inexpensive feedstocks to highly functionalized, versatile intermediates. Vanadium is an important component of mixed metal oxide catalysts used in the oxidation of propane and propylene to acrolein, acrylic acid or the ammoxidation of propylene to acrylonitrile. In service, the oxidation state of vanadium changes dynamically and reversibly with the oxygen and the steam content of the reacting feed mixture.

Like most polyunsaturated fatty acids and mono-hydroxyl polyunsaturated fatty acids, 13(S)-HODE is rapidly and quantitatively incorporated into phospholipids; the levels of 13(S)-HODE esterified to the sn-2 position of phosphatidylcholine, phosphatidylinositol, and phosphatidylethanolamine in human psoriasis lesions are significantly lower than those in normal skin; this chain shortening pathway may be responsible for inactivating 13(S)-HODE. 13(S)-HODE is also metabolized by peroxisome- dependent β-oxidations to chain-shortened 16-carbon, 14-carbon, and 12-carbon products which are released from the cell; this chain-shortening pathway may serve to inactive and dispose of 13(S)-HODE. 13(S)-HODE is oxidized to 13-oxo-9Z,11E-octadecadienoic acid (13-oxo-HODE or 13-oxoODE) by a NAD+-dependent 13-HODE dehydrogenase, the protein for which has been partially purified from rat colon. The formation of 13-oxo-ODE may represent the first step in 13(S)-HODEs peroxisome-dependent chain shortening but 13-oxo-ODE has its own areas of biological importance: it accumulates in tissues, is bioactive, and may have clinically relevance as a marker for and potential contributor to human disease.