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In organic chemistry, aldol reactions are acid- or base-catalyzed reactions of aldehydes or ketones. Aldol addition or aldolization refers to the addition of an enolate or enolation as a nucleophile to a carbonyl moiety as an electrophile. This produces a β-hydroxyaldehyde or β-hydroxyketone.
An aldol condensation is a condensation reaction in organic chemistry in which two carbonyl moieties (of aldehydes or ketones) react to form a β-hydroxyaldehyde or β-hydroxyketone (an aldol reaction), and this is then followed by dehydration to give a conjugated enone. The overall reaction equation is as follows (where the Rs can be H)
The aldol reaction (aldol addition) is a reaction in organic chemistry that combines two carbonyl compounds (e.g. aldehydes or ketones) to form a new β-hydroxy carbonyl compound. Its simplest form might involve the nucleophilic addition of an enolized ketone to another:
α-Hydroxy imines may also undergo rearrangement to amino ketones. Hammett analysis and a very negative entropy of activation suggest that the reaction proceeds in a single step through a concerted transition state. [9] As a result, subtle conformational and steric factors can play a role in the speed and extent of these reactions.
The reaction was discovered by Teruaki Mukaiyama in 1973. [2] His choice of reactants allows for a crossed aldol reaction between an aldehyde and a ketone (>C=O), or a different aldehyde without self-condensation of the aldehyde. For this reason the reaction is used extensively in organic synthesis.
Quantitative yields in Claisen–Schmidt reactions have been reported in the absence of solvent using sodium hydroxide as the base and plus benzaldehydes. [5] Because the enolizable nucleophilic carbonyl compound and the electrophilic carbonyl compound are two different chemicals, the Claisen–Schmidt reaction is an example of a crossed aldol ...
The Buchner–Curtius–Schlotterbeck reaction is the reaction of aldehydes or ketones with aliphatic diazoalkanes to form homologated ketones. [1] It was first described by Eduard Buchner and Theodor Curtius in 1885 [ 2 ] and later by Fritz Schlotterbeck in 1907. [ 3 ]
The Darzens reaction (also known as the Darzens condensation or glycidic ester condensation) is the chemical reaction of a ketone or aldehyde with an α-haloester in the presence of a base to form an α,β-epoxy ester, also called a "glycidic ester". [1] [2] [3] This reaction was discovered by the organic chemist Auguste Georges Darzens in 1904 ...