The Darzens Glycidic Ester Condensation

The Darzens glycidic ester condensation involves the condensation of an aldehdye and a ketone with an alpha-halo ester to produce an alpha,beta-epoxy ester (glycidic ester). The most frequently used condensing agents are sodium ethoxide and sodium amide. The glycidic esters are of interest primarily because they can be converted into aldehydes and ketones having a higher carbon content than the original aldehydes or ketones. This transformation occurs after hydrolysis to and decarboxylation of the epoxy acid and is accompanied by rearrangement when an aldehyde if formed. Darzens described another procedure which involves the reaction of aldehdyes and ketones with ethyl dichloracetate and dilute magnesium amalgam. Mechanisms of these reactions are discussed. Keywords: Darzens reaction; glycidic ester condensation; aldehydes; ketones; Grignard reaction; glycidic esters; dichloracetate synthesis; side reactions; experimental procedures