乙酰丙酸，结构式CH₃COCH₂CH₂COOH。

白色片状有吸湿性结晶。易溶于水和醇、醚等多数有机溶剂。常压蒸馏几乎不分解，但长时间加热则发生失水转变为不饱和的五元内酯——α-当归内酯和β-当归内酯。易燃；低毒。

Levulinic acid, or 4-oxopentanoic acid, is an organic compound with the formula CH₃C(O)CH₂CH₂CO₂H. It is classified as a keto acid. This white crystalline solid is soluble in water and polar organic solvents. It is derived from degradation of cellulose and is a potential precursor to biofuels.