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Enamine
An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine. Enamines are versatile intermediates. : The word "enamine" is derived from the affix ''en''-, used as the suffix of alkene, and the root ''amine''. This can be compared with enol, which is a functional group containing both alkene (''en''-) and alcohol (-''ol''). Enamines are considered to be nitrogen analogs of enols. If one of the nitrogen substituents is a hydrogen atom, H, it is the tautomeric form of an imine. This usually will rearrange to the imine; however there are several exceptions (such as aniline). The enamine-imine tautomerism may be considered analogous to the keto-enol tautomerism. In both cases, a hydrogen atom switches its location between the heteroatom (oxygen or nitrogen) and the second carbon atom. Enamines are both good nucleophiles and good bases. Their behavior as carbon-based nucleophiles is explained with reference to the following reson ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enamine Acylation To Form A Dicarbonyl Species
An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine. Enamines are versatile intermediates. : The word "enamine" is derived from the affix ''en''-, used as the suffix of alkene, and the root ''amine''. This can be compared with enol, which is a functional group containing both alkene (''en''-) and alcohol (-''ol''). Enamines are considered to be nitrogen analogs of enols. If one of the nitrogen substituents is a hydrogen atom, H, it is the tautomeric form of an imine. This usually will rearrange to the imine; however there are several exceptions (such as aniline). The enamine-imine tautomerism may be considered analogous to the keto-enol tautomerism. In both cases, a hydrogen atom switches its location between the heteroatom (oxygen or nitrogen) and the second carbon atom. Enamines are both good nucleophiles and good bases. Their behavior as carbon-based nucleophiles is explained with reference to the following resonan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enamine Alkylation Via SN2 Reaction With A Bromo-alkane
An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine. Enamines are versatile intermediates. : The word "enamine" is derived from the affix ''en''-, used as the suffix of alkene, and the root ''amine''. This can be compared with enol, which is a functional group containing both alkene (''en''-) and alcohol (-''ol''). Enamines are considered to be nitrogen analogs of enols. If one of the nitrogen substituents is a hydrogen atom, H, it is the tautomeric form of an imine. This usually will rearrange to the imine; however there are several exceptions (such as aniline). The enamine-imine tautomerism may be considered analogous to the keto-enol tautomerism. In both cases, a hydrogen atom switches its location between the heteroatom (oxygen or nitrogen) and the second carbon atom. Enamines are both good nucleophiles and good bases. Their behavior as carbon-based nucleophiles is explained with reference to the following resonan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enamine
An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine. Enamines are versatile intermediates. : The word "enamine" is derived from the affix ''en''-, used as the suffix of alkene, and the root ''amine''. This can be compared with enol, which is a functional group containing both alkene (''en''-) and alcohol (-''ol''). Enamines are considered to be nitrogen analogs of enols. If one of the nitrogen substituents is a hydrogen atom, H, it is the tautomeric form of an imine. This usually will rearrange to the imine; however there are several exceptions (such as aniline). The enamine-imine tautomerism may be considered analogous to the keto-enol tautomerism. In both cases, a hydrogen atom switches its location between the heteroatom (oxygen or nitrogen) and the second carbon atom. Enamines are both good nucleophiles and good bases. Their behavior as carbon-based nucleophiles is explained with reference to the following reson ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enamine Synthesis From A Secondary Amine And An Aldehyde
An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine. Enamines are versatile intermediates. : The word "enamine" is derived from the affix ''en''-, used as the suffix of alkene, and the root ''amine''. This can be compared with enol, which is a functional group containing both alkene (''en''-) and alcohol (-''ol''). Enamines are considered to be nitrogen analogs of enols. If one of the nitrogen substituents is a hydrogen atom, H, it is the tautomeric form of an imine. This usually will rearrange to the imine; however there are several exceptions (such as aniline). The enamine-imine tautomerism may be considered analogous to the keto-enol tautomerism. In both cases, a hydrogen atom switches its location between the heteroatom (oxygen or nitrogen) and the second carbon atom. Enamines are both good nucleophiles and good bases. Their behavior as carbon-based nucleophiles is explained with reference to the following resonan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Imine
In organic chemistry, an imine ( or ) is a functional group or organic compound containing a carbon–nitrogen double bond (). The nitrogen atom can be attached to a hydrogen or an organic group (R). The carbon atom has two additional single bonds. Imines are common in synthetic and naturally occurring compounds and they participate in many reactions. Structure For ketimines and aldimines, respectively, the five core atoms (C2C=NX and C(H)C=NX, X = H or C) are coplanar. Planarity results from the sp2-hybridization of the mutually double-bonded carbon and the nitrogen atoms. The C=N distance is 1.29-1.31 Å for nonconjugated imines and 1.35 Å for conjugated imines. By contrast, C-N distances in amines and nitriles are 1.47 and 1.16 Å, respectively. Rotation about the C=N bond is slow. Using NMR spectroscopy, both E- and Z-isomers of aldimines have been detected. Owing to steric effects, the E isomer is favored. Nomenclature and classification The term "imine" was coine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stork Enamine Alkylation
The Stork enamine alkylation involves the addition of an enamine to a Michael acceptor (e.g, an α,β -unsaturated carbonyl compound) or another electrophilic alkylation reagent to give an alkylated iminium product, which is hydrolyzed by dilute aqueous acid to give the alkylated ketone or aldehyde. Since enamines are generally produced from ketones or aldehydes, this overall process (known as the Stork enamine synthesis) constitutes a selective monoalkylation of a ketone or aldehyde, a process that may be difficult to achieve directly. The Stork enamine synthesis: # formation of an enamine from a ketone # addition of the enamine to an alpha, beta-unsaturated aldehyde or ketone # hydrolysis of the enamine back to a ketone The reaction also applies to acyl halides as electrophiles, which results in the formation of 1,3-diketones (Stork acylation). It is also effective for activated sp3 alkyl electrophiles, including benzylic, allylic/propargylic, α-carbonyl (e.g., bromoace ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrrolidine
Pyrrolidine, also known as tetrahydropyrrole, is an organic compound with the molecular formula (CH2)4NH. It is a cyclic secondary amine, also classified as a saturated heterocycle. It is a colourless liquid that is miscible with water and most organic solvents. It has a characteristic odor that has been described as "ammoniacal, fishy, shellfish-like". In addition to pyrrolidine itself, many substituted pyrrolidines are known. Production and synthesis Industrial production Pyrrolidine is prepared industrially by the reaction of 1,4-butanediol and ammonia at a temperature of 165–200 °C and a pressure of 17–21 MPa in the presence of a cobalt- and nickel oxide catalyst, which is supported on alumina. : The reaction is carried out in the liquid phase in a continuous tube- or tube bundle reactor, which is operated in the cycle gas method. The catalyst is arranged as a fixed-bed and the conversion is carried out in the downflow mode. The product is obtained after mu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scavenger (chemistry)
A scavenger in chemistry is a chemical substance added to a mixture in order to remove or de-activate impurities and unwanted reaction products, for example oxygen, to make sure that they will not cause any unfavorable reactions. Their use is wide-ranged: * In atmospheric chemistry, the most common scavenger is the hydroxyl radical, a short-lived radical produced photolytically in the atmosphere. It is the most important oxidant for carbon monoxide, methane and other hydrocarbons, sulfur dioxide, hydrogen sulfide, and most of other contaminants, removing them from the atmosphere. * In molecular laser isotope separation, methane is used as a scavenger gas for fluorine atoms. * Hydrazine and ascorbic acid are used as oxygen scavenger corrosion inhibitors. * Tocopherol and naringenin are bioactive free radical scavengers that act as antioxidants; synthetic catalytic scavengers are their synthetic counterparts * Organotin compounds are used in polymer manufacture as hydrochloric acid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbinolamine
In organic chemistry, a hemiaminal (also carbinolamine) is a functional group or type of chemical compound that has a hydroxyl group and an amine attached to the same carbon atom: . R can be hydrogen or an alkyl group. Hemiaminals are intermediates in imine formation from an amine and a carbonyl by alkylimino-de-oxo-bisubstitution. Hemiaminals can be viewed as a blend of aminals and geminal diol. They are a special case of amino alcohols. Classification according to amine precursor Addition of ammonia The adducts formed by the addition of ammonia to aldehydes have long been studied. Compounds containing both a primary amino group and a hydroxyl group bonded to the same carbon atom are rare. They are invoked but rarely observed as intermediates in the reaction of ammonia and aldehydes and ketones. One example of this rare functionality is the adduct of ammonia and hexafluoroacetone, . The C-substituted derivatives are obtained by reaction of aldehydes and ammonia: :3 RCHO + 3 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haloalkanes
The haloalkanes (also known as halogenoalkanes or alkyl halides) are alkanes containing one or more halogen substituents. They are a subset of the general class of halocarbons, although the distinction is not often made. Haloalkanes are widely used commercially. They are used as flame retardants, fire extinguishants, refrigerants, propellants, solvents, and pharmaceuticals. Subsequent to the widespread use in commerce, many halocarbons have also been shown to be serious pollutants and toxins. For example, the chlorofluorocarbons have been shown to lead to ozone depletion. Methyl bromide is a controversial fumigant. Only haloalkanes that contain chlorine, bromine, and iodine are a threat to the ozone layer, but fluorinated volatile haloalkanes in theory may have activity as greenhouse gases. Methyl iodide, a naturally occurring substance, however, does not have ozone-depleting properties and the United States Environmental Protection Agency has designated the compound a non-ozone l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gilbert Stork
Gilbert Stork (December 31, 1921 – October 21, 2017) was an organic chemist. For a quarter of a century he was the Eugene Higgins Professor of Chemistry Emeritus at Columbia University. He is known for making significant contributions to the total synthesis of natural products, including a lifelong fascination with the synthesis of quinine. In so doing he also made a number of contributions to mechanistic understanding of reactions, and performed pioneering work on enamine chemistry, leading to development of the Stork enamine alkylation. It is believed he was responsible for the first planned stereocontrolled synthesis as well as the first natural product to be synthesised with high stereoselectivity. Stork was also an accomplished mentor of young chemists and many of his students have gone on to make significant contributions in their own right. Early years Gilbert Stork was born in the Ixelles municipality of Brussels, Belgium on December 31, 1921. The oldest of 3 childre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iminium
In organic chemistry, an iminium cation is a polyatomic ion with the general structure . They are common in synthetic chemistry and biology. Structure Iminium cations adopt alkene-like geometries. The central C=N unit is nearly coplanar with all four substituents. The C=N distances, which are near 129 picometers in length, are shorter than C-N single bonds. Cis/trans isomers are observed. Formation Iminium cations are obtained by protonation and alkylation of imines: :RN=CR'_2 + H+ -> NH=CR'_2 :RN=CR'_2 + R''+ -> R''N=CR'_2 They also are generated by the condensation of secondary amines with ketones or aldehydes: :O=CR'_2 + R2NH + H+ 2N=CR'_2 + H2O This rapid, reversible reaction is one step in "iminium catalysis". More exotic routes to iminium cations are known, e.g. from ring-opening reactions of pyridine. Occurrence Iminium derivatives are common in biology. Pyridoxal phosphate reacts with amino acids to give iminium derivatives. Many iminium salts are en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
