Alpha Carbon Reactions

Vocabulary

acetoacetic ester synthesis

method for ketone preparation in which alkylation of the enolate of ethyl acetoacetate is followed by reaction with H3O+ and heat to decarboxylate the acetic ester

addition reaction

reaction in which two or more reactants combine to form products

aldol

molecule formed from the reaction of an enolate with a carbonyl, composed of a carbonyl and an alcohol

aldol addition reaction

reaction in which aldehydes and/or ketones are treated with a base to yield a solution containing a carbonyl compound and its enolate, which combine through the formation of a CC {\rm{C{-}C}} bond

aldol condensation reaction

aldol addition wherein the beta-hydroxy aldehyde or ketone dehydrates

alkylation

reaction in which an alkyl group is transferred from one molecule to another organic compound

alpha,beta-unsaturated molecule

molecule with a pi bond between the alpha (α \alpha) and beta (β \beta) carbons attached to a carbonyl group

Claisen condensation

formation of a beta-keto ester from an ester and a base

condensation reaction

chemical reaction that combines two molecules together with the elimination of a water molecule

conjugate addition

reaction in which a nucleophile reacts with an alpha,beta-unsaturated carbonyl compound in the beta position

decarboxylation

removal of a carboxylic acid (as a CO2 group) by the addition of heat

directed aldol reaction

reaction in which the enolate is prepared in the first step and the intended reactant is added in the second step to ensure the desired product

directed Claisen condensation

reaction in which an ester is treated with lithium diisopropylamide (LDA) or another strong base, followed by the addition of a second ester

enamine

amino group containing the double bond linkage C=CN{\rm{C{=}C{-}N}}

enolate

anion formed when an alpha hydrogen in the molecule of an aldehyde or a ketone is removed as a hydrogen ion

haloform reaction

cleavage of a methyl ketone by Br2, Cl2, or I2 to form CHX3 (where X is Br, Cl, or I)

halogenation

reaction in which a hydrogen is replaced by a halogen

Hell-Volhard-Zelinsky (HVZ) halogenation reaction

halogenation of a carboxylic acid catalyzed by phosphorus trihalide

intramolecular aldol reaction

reaction in which the enolate and carbonyl components are parts of a single molecule

intramolecular Claisen condensation

reaction in which an ester is deprotonated at the alpha carbon, generating an enolate, which undergoes an intramolecular nucleophilic attack, yielding a cyclic enol. The enol is protonated with an acid to re-form the beta-keto ester.

malonic ester synthesis

preparation of a carboxylic acid by alkylation of the enolate of diethyl malonate

Michael reaction

1,4-addition reaction in which a carbanion is added to an alpha,beta-unsaturated carbonyl compound

practical crossed aldol reaction

reaction in which two different carbonyl compounds are mixed together and only one can form an enolate, preventing self-condensation of the other compound

practical crossed Claisen condensation

ester or ketone enolate mixed with an ester that cannot form an enolate

retro-aldol reaction

reverse of an aldol reaction. It decomposes a beta-hydroxy carbonyl into an aldehyde or ketone and another carbonyl compound.

Robinson annulation

reaction in which a Michael reaction is followed by an intramolecular aldol condensation to form a cyclohexenone ring

Stork enamine reaction

reaction in which ketones are alkylated or acylated through intermediate enamines