Acetoacetic acid is a colorless, organic compound with the chemical formula C4H6O3. It is a type of ketone and is primarily used in the synthesis of various chemicals, including pharmaceuticals and dyes. Acetoacetic acid can be produced through the decarboxylation of acetoacetate or by the oxidation of butyric acid. In biological systems, acetoacetic acid plays a role in the metabolism of fats and carbohydrates. It is one of the ketone bodies produced during periods of fasting or low carbohydrate intake, serving as an alternative energy source for cells. This compound is important in the study of metabolic disorders and the ketogenic diet.