Ethyl acetoacetate

The organic compound ethyl acetoacetate (EAA) is the ethyl ester of acetoacetic acid. It is a colorless liquid. It is widely used as a chemical intermediate in the production of a wide variety of compounds.

At large scale, ethyl acetoacetate is industrially produced by treatment of diketene with ethanol.

The small scale preparation of ethyl acetoacetate is a classic laboratory procedure. It involves Claisen condensation of ethyl acetate. Two moles of ethyl acetate condense to form one mole each of ethyl acetoacetate and ethanol.

Ethyl acetoacetate is subject to keto-enol tautomerism. In the neat liquid at 33 °C, the enol consists of 8% of the total.

The enol is moderately acidic. Thus ethyl acetoacetate behaves similarly to acetylacetone:

The resulting carbanion undergoes nucleophilic substitution. Ethyl acetoacetate is often used in the acetoacetic ester synthesis, comparable to diethyl malonate in the malonic ester synthesis or the Knoevenagel condensation. After its alkylation and saponification, thermal decarboxylation is also possible.

The dianion of ethyl acetoacetate is also a useful building block, except that the electrophile adds to the terminal carbon. The strategy can be depicted in the following simplified form:

Reduction of ethyl acetoacetate gives ethyl 3-hydroxybutyrate.