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Decarbonylation
Decarbonylation is a type of organic reaction that involves loss of CO. It is often an undesirable reaction since it represents a degradation. In the chemistry of metal carbonyls, decarbonylation describes a substitution process, whereby a CO ligand is replaced by another ligand. Organic chemistry In the absence of metal catalysts, decarbonylation (vs decarboxylation) is rarely observed in organic chemistry. One exception is the decarbonylation of formic acid: :HCO2H → CO + H2O The reaction is induced by sulfuric acid, which functions as both a catalyst and a dehydrating agent. Via this reaction, formic acid is occasionally employed as a source of CO in the laboratory in lieu of cylinders of this toxic gas. With strong heating, formic acid and some of its derivatives may undergo decarbonylation, even without adding a catalyst. For instance, dimethylformamide slowly decomposes to give dimethylamine and carbon monoxide when heated to its boiling point (154 °C). S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tsuji–Wilkinson Decarbonylation Reaction
The Tsuji–Wilkinson decarbonylation reaction is a method for the decarbonylation of aldehydes and some acyl chlorides. The reaction name recognizes , whose team first reported the use of Wilkinson's catalyst (RhCl(PPh3)3) for these reactions: :RC(O)X + RhCl(PPh3)3 → RX + RhCl(CO)(PPh3)2 + PPh3 Although decarbonylation can be effected by several transition metal complexes, Wilkinson's catalyst has proven the most effective. Reaction mechanism Strictly speaking, this reaction results in the formation of a rhodium carbonyl complex rather than free carbon monoxide. The catalytic cycle is assumed to involve oxidative addition of the aldehyde (or acid chloride) to gives a 16e acyl Rh(III)-hydride intermediate, which undergoes migratory extrusion of CO proceed to form an 18-electron d6 Rh(III) carbonyl complex. Reductive elimination produces the decarbonylated product. In the catalytic variant of the Tsuji–Wilkinson decarbonylation, RhCl(CO)(PPh3)2 evolves CO above ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimethylformamide
Dimethylformamide is an organic compound with the formula ( CH3)2NC(O)H. Commonly abbreviated as DMF (although this initialism is sometimes used for dimethylfuran, or dimethyl fumarate), this colourless liquid is miscible with water and the majority of organic liquids. DMF is a common solvent for chemical reactions. Dimethylformamide is odorless, but technical-grade or degraded samples often have a fishy smell due to impurity of dimethylamine. Dimethylamine degradation impurities can be removed by sparging samples with an inert gas such as argon or by sonicating the samples under reduced pressure. As its name indicates, it is structurally related to formamide, having two methyl groups in the place of the two hydrogens. DMF is a polar ( hydrophilic) aprotic solvent with a high boiling point. It facilitates reactions that follow polar mechanisms, such as SN2 reactions. Structure and properties As for most amides, the spectroscopic evidence indicates partial double bond ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Hydroxy Acid
α-Hydroxy acids, or alpha hydroxy acids (AHAs), are a class of chemical compounds that consist of a carboxylic acid with a hydroxyl group substituent on the adjacent (alpha) carbon. Prominent examples are glycolic acid, lactic acid, mandelic acid and citric acid. Although these compounds are related to the ordinary carboxylic acids and are therefore weak acids, their chemical structure allows for the formation of an internal hydrogen bond between the hydrogen at the hydroxyl group and one of the oxygen atoms of the carboxylic group. The net effect is an increase in acidity. For example, the pKa of lactic acid is 3.86, while that of the unsubstituted propionic acid is 4.87; a full pKa unit difference means that lactic acid is ten times stronger than propionic acid. Industrial applications Feed additives 2-Hydroxy-4-(methylthio)butyric acid is produced commercially as a racemic mixture to substitute for methionine in animal feed. In nature, the same compound is an intermediate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acyl Hydride
In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group. Aldehydes are common and play important roles in the technology and biological spheres. Structure and bonding Aldehydes feature a carbon center that is connected by a double bond to oxygen and a single bond to hydrogen and single bond to a third substituent, which is carbon or, in the case of formaldehyde, hydrogen. The central carbon is often described as being sp2- hybridized. The aldehyde group is somewhat polar. The C=O bond length is about 120-122 picometers. Physical properties and characterization Aldehydes have properties that are diverse and that depend on the remainder of the molecule. Smaller aldehydes are more soluble in water, formaldehyde and acetaldehyde completely so. The volatile aldehydes have pungent odors. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aldehyde
In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group. Aldehydes are common and play important roles in the technology and biological spheres. Structure and bonding Aldehydes feature a carbon center that is connected by a double bond to oxygen and a single bond to hydrogen and single bond to a third substituent, which is carbon or, in the case of formaldehyde, hydrogen. The central carbon is often described as being sp2- hybridized. The aldehyde group is somewhat polar. The C=O bond length is about 120-122 picometers. Physical properties and characterization Aldehydes have properties that are diverse and that depend on the remainder of the molecule. Smaller aldehydes are more soluble in water, formaldehyde and acetaldehyde completely so. The volatile aldehydes have pungent odors. Al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wilkinson's Catalyst
Wilkinson's catalyst is the common name for chloridotris(triphenylphosphine)rhodium(I), a coordination complex of rhodium with the formula hCl(PPh3)3(Ph = phenyl). It is a red-brown colored solid that is soluble in hydrocarbon solvents such as benzene, and more so in tetrahydrofuran or chlorinated solvents such as dichloromethane. The compound is widely used as a catalyst for hydrogenation of alkenes. It is named after chemist and Nobel laureate Sir Geoffrey Wilkinson, who first popularized its use. Historically, Wilkinson's catalyst has been a paradigm in catalytic studies leading to several advances in the field such as the implementation of some of the first heteronuclear magnetic resonance studies for its structural elucidation in solution (31P), parahydrogen-induced polarization spectroscopy to determine the nature of transient reactive species, or one of the first detailed kinetic investigation by Halpern to elucidate the mechanism. Furthermore, the catalytic and organo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimethylformamide
Dimethylformamide is an organic compound with the formula ( CH3)2NC(O)H. Commonly abbreviated as DMF (although this initialism is sometimes used for dimethylfuran, or dimethyl fumarate), this colourless liquid is miscible with water and the majority of organic liquids. DMF is a common solvent for chemical reactions. Dimethylformamide is odorless, but technical-grade or degraded samples often have a fishy smell due to impurity of dimethylamine. Dimethylamine degradation impurities can be removed by sparging samples with an inert gas such as argon or by sonicating the samples under reduced pressure. As its name indicates, it is structurally related to formamide, having two methyl groups in the place of the two hydrogens. DMF is a polar ( hydrophilic) aprotic solvent with a high boiling point. It facilitates reactions that follow polar mechanisms, such as SN2 reactions. Structure and properties As for most amides, the spectroscopic evidence indicates partial double bond ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swern Oxidation
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 by-products are dimethyl sulfide ((CH3)2S), carbon monoxide (CO), carbon dioxide (CO2) and—when triethylamine is used as base— triethylammonium chloride (Et3NHCl). Of the volatile by-products, dimethyl sulfide has a strong, pervasive odour and carbon monoxide is acutely toxic, so the reaction and the work-up needs to be performed in a fume hood. Dimethyl sulfide is a volatile liquid (B.P. 37 °C) with an unpleasant odour at even low concentrations. Mechanism The first step of the Swern oxidation is the low-temperature reaction of DMSO, 1a, formally as res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DMC From DMO
DMC may refer to: Computer science and information technology * Diffusion Monte Carlo method * Dynamic Markov Compression algorithm * Digital Media Controller, a category within the DLNA standard * Data Matrix Code, laser etched square code, often used for marking products in the production area * Discrete memoryless channel Media and entertainment * Digital mixing console * Darryl McDaniels, a member of hip hop group Run–DMC * '' Devil May Cry'', a Japanese video game series ** ''Devil May Cry'' (video game), the first game in the series ** '' DmC: Devil May Cry'', a reboot of the series * ''Detroit Metal City'', a manga franchise * Disco Mix Club, a remix label * Dhammakaya Media Channel, a Thai television channel * Deathmatch Classic, a ''Half-Life'' mod * Drummond Money-Coutts, an English magician * DMC (Egyptian TV channel), an Arabic-language channel Motor vehicles * DeLorean Motor Company * DeLorean Motor Company (Texas) * Daelim Motor Company, South Korea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vaska's Complex
Vaska's complex is the trivial name for the chemical compound ''trans''-carbonylchlorobis(triphenylphosphine)iridium(I), which has the formula IrCl(CO) (C6H5)3sub>2. This square planar diamagnetic organometallic complex consists of a central iridium atom bound to two mutually ''trans'' triphenylphosphine ligands, carbon monoxide and a chloride ion. The complex was first reported by J. W. DiLuzio and Lauri Vaska in 1961. Vaska's complex can undergo oxidative addition and is notable for its ability to bind to O2 reversibly. It is a bright yellow crystalline solid. Preparation The synthesis involves heating virtually any iridium chloride salt with triphenylphosphine and a carbon monoxide source. The most popular method uses dimethylformamide (DMF) as a solvent, and sometimes aniline is added to accelerate the reaction. Another popular solvent is 2-methoxyethanol. The reaction is typically conducted under nitrogen. In the synthesis, triphenylphosphine serves as both a ligand and a re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heme Oxygenase
Heme oxygenase, or haem oxygenase, (HMOX, commonly abbreviated as HO) is an enzyme that catalyzes the degradation of heme to produce biliverdin, ferrous ion, and carbon monoxide. There are many heme degrading enzymes in nature. In general, only aerobic heme degrading enzymes are referred to as HMOX-like enzymes whereas anaerobic enzymes are typically not affiliated with the HMOX family. Heme oxygenase Heme oxygenase (alternatively spelled using haem or oxidase) catalyzes the degradation of heme to biliverdin/bilirubin, ferrous ion, and carbon monoxide. The human genome may encode three isoforms of HMOX. The degradation of heme forms three distinct chromogens as seen in healing cycle of a bruise. This reaction can occur in virtually every cell and platelet; the classic example is the healing process of a contusion, which forms different chromogens as it gradually heals: (red) heme to (green) biliverdin to (yellow) bilirubin which is widely known for jaundice. In general, as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkyne
\ce \ce Acetylene \ce \ce \ce Propyne \ce \ce \ce \ce 1-Butyne In organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. The simplest acyclic alkynes with only one triple bond and no other functional groups form a homologous series with the general chemical formula . Alkynes are traditionally known as acetylenes, although the name ''acetylene'' also refers specifically to , known formally as ethyne using IUPAC nomenclature. Like other hydrocarbons, alkynes are generally hydrophobic. Structure and bonding In acetylene, the H–C≡C bond angles are 180°. By virtue of this bond angle, alkynes are rod-like. Correspondingly, cyclic alkynes are rare. Benzyne cannot be isolated. The C≡C bond distance of 121 picometers is much shorter than the C=C distance in alkenes (134 pm) or the C–C bond in alkanes (153 pm). : The triple bond is very strong with a bond strength of 839 kJ/mol. The sigma bond contri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
