3128-06-1 4-Acetylbutyric acid 5-Ketocaproic acid 5-Ketohexanoic acid 5-OXOHEXANOIC ACID EINECS 221-511-7 Hexanoic acid, 5-oxo- NSC 5281 delta-Ketocaproic acid delta-Oxocaproic acid gamma-Acetylbutyric acid