3-oxobutanoic acid ethyl ester ETHYL-ACETOACETATE acetoacetic acid, ethyl ester active acetyl acetate butanoic acid, 3-oxo-ethyl ester diacetic ether ethyl 3-oxobutanoate ethyl 3-oxobutyrate ethyl acetoacetate ethyl acetylacetate ethyl acetylacetonate ethyl beta-ketobutyrate