ABSTRACT
Ketones and aldehydes react with nucleophile primarily by acyl addition, whereas acid derivatives proceed by acyl substitution. In addition, aldehydes, ketones, or esters that have a proton on the carbon directly connected to the carbonyl carbon, the +¦-carbon are weak acids. This chapter discusses the formation and nucleophilic reactions of enols and enolate anions. Therefore, the hydrogen atom on the +¦-carbon, the +¦-proton, makes ketones and aldehydes weak acids. Both of these two resonance contributors represent 2-oxopropan-1-ide, of course, so it is possible to view enolate anion formation by deprotonation of the enol rather than the keto form. Enolate anions are carbanions, because the resonance-stabilized enolate anion has a larger concentration of electron density on the carbon relative to oxygen. Formation of a new C-C bond generates an alkoxide, and the carbonyl of the ketone enolate anion remains so the product is the keto-alkoxide.
