malonic ester[mə′län·ik ′es·tər]
a diethyl ester of malonic acid, H2C(COOC2H5)2; a colorless liquid with a fruity odor. Boiling point, 199°C; density, 1.055 g/cm3 at 20°C. Malonic ester is poorly soluble in water but dissolves readily in organic solvents. It is usually obtained upon interaction of sodium cyanoacetate, N≡CCH2COONa, and ethyl alcohol, C2H5OH, in the presence of sulfuric acid. An important property of malonic ester is its ability to readily replace the hydrogen atoms in the CH2 group by metal atoms. The resulting metallic derivatives (for example, sodium and dibasic sodium malonic esters) are widely used in the synthesis of various organic compounds (carboxylic acids and ketones). For example,
The condensation of malonic ester and certain of its alkyl or aryl derivatives with urea results in the formation of barbituric acid and alkyl- or aryl-substituted derivatives of barbituric acid, respectively, which are used as soporifics.