Ethyl 4-oxopentanoate 4-oxopentanoic acid ethyl ester 4-ketovaleric acid ethyl ester 539-88-8 122629_ALDRICH ZINC03860971 W244201_ALDRICH 61395_FLUKA NSC24876 4-03-00-01562 (Beilstein Handbook Reference) AI3-00677 BRN 0507641 EINECS 208-728-2 Ethyl acetylpropanoate Ethyl ketovalerate Ethyl levulinate (natural) FEMA No. 2442 NSC 24876 ELA Ethyl 3-acetylpropionate Ethyl 4-ketovalerate Ethyl 4-oxovalerate Ethyl laevulinate Ethyl levulate Ethyl levulinate Levulinic acid, ethyl ester NSC8863 Pentanoic acid, 4-oxo-, ethyl ester