Malonic ester synthesis is a synthetic reaction that converts an alkyl halide to a carboxylic acid. It consists of four consecutive reactions, including an acid-base reaction, nucleophilic substitution, ester hydrolysis using saponification and decarboxylation. Malonic esters are esters of malonic, or propanedioic, acid.
Malonic esters are more simple than acidic esters. Their alkylations are done via enolate formation with the aid of mild bases such as sodium alkoxide. Alkylation of halides then occurs. Diethyl malonate, with the systematic name diethyl propandioate, is a common example of a malonic ester. It is a readily available starting material and an example of an active methylene compound.