Ethyl acetoacetate


The organic compound ethyl acetoacetate is the ethyl ester of acetoacetic acid. It is mainly used as a chemical intermediate in the production of a wide variety of compounds, such as amino acids, analgesics, antibiotics, antimalarial agents, antipyrine and aminopyrine, and vitamin B1; as well as the manufacture of dyes, inks, lacquers, perfumes, plastics, and yellow paint pigments. Alone, it is used as a flavoring for food.

Preparation

Ethyl acetoacetate is produced industrially by treatment of diketene with ethanol.
The preparation of ethyl acetoacetate is a classic laboratory procedure. It is prepared via the Claisen condensation of ethyl acetate. Two moles of ethyl acetate condense to form one mole each of ethyl acetoacetate and ethanol.

Reactivity

Ethyl acetoacetate is subject to keto-enol tautomerism. In the neat liquid at 33 °C, the enol consists of 15% of the total.

Ethyl acetoacetate is often used in the acetoacetic ester synthesis similar to diethyl malonate in the malonic ester synthesis or the Knoevenagel condensation. The protons alpha to carbonyl groups are acidic, and the resulting carbanion can undergo nucleophilic substitution. A subsequent thermal decarboxylation is also possible. Similar to the behavior of acetylacetone, the enolate of ethyl acetoacetate can also serve as a bidentate ligand. For example, it forms purple coordination complexes with iron salts:
Ethyl acetoacetate can also be reduced to ethyl 3-hydroxybutyrate.
Ethyl acetoacetate, when heated alone with benzyl alcohol, forms synthetically useful benzyl acetoacetate, via a mechanism involving acetylketene. Ethyl acetoacetates nitrosate readily with equimolar sodium nitrite in acetic acid, to afford the corresponding oximinoacetoacetate esters. A dissolving-zinc reduction of these in acetic acid in the presence of ketoesters or beta-diketones constitute the Knorr synthesis of pyrroles, useful for porphyrin synthesis.