acetoacetic ester[¦as·ə‚tō‚ə′sēd·ik ′es·tər]
an organic compound; a colorless liquid with pleasant odor. It boils at 181°C with partial decomposition. Its density is 1,028.2 kg/m3. Acetoacetic ester consists of a mixture of the keto (I) and enol (II) forms. Both forms are found in a state of equilibrium—the so-called keto-enol tautomerism:
CH3COCH2COOC2H5 ⇌ CH3 = CHCOOC2H5
The state of the equilibrium depends on the temperature, the solvent, and the material of the container walls. The properties of ketones and enols are inherent simultaneously in ordinary acetoacetic ester (a mixture of both forms). Hence, acetoacetic ester as a ketone combines with hydrocyanic acid or sodium bisulfite, and as an enol it gives a violet dye with ferric chloride, combines bromine in the multiple bond, and so on.
Acetoacetic ester was first obtained from ethyl acetate by the action of metallic sodium upon it:
The industrial method for obtaining acetoacetic ester is by the action of sodium alkoxide on ethyl acetate. Acetoacetic ester is used in the production of aminopyrine and quinacrine hydrochloride (acriquine), vitamin B1, pyrazolone dyes, and other substances.