2hydroxy3methylbutyric

2-hydroxy-3-methylbutanoic acid (commonly referred to as 2hydroxy3methylbutyric acid) is a branched-chain alpha-hydroxy carboxylic acid with the formula C5H10O3. Its IUPAC designation is 2-hydroxy-3-methylbutanoic acid, and it can also be called 2-hydroxy-3-methylbutyrate in the ester form. The molecule contains a carboxyl group and a secondary alcohol positioned on adjacent carbons of a five‑carbon chain that bears a methyl substituent at the γ‑position.

The compound is produced naturally in small amounts during the fermentation of certain foods and by some microorganisms. It is also obtainable synthetically by the selective reduction of 3-methyl-2-oxobutanoic acid or by hydrolysis of the corresponding ester, followed by recrystallisation. In laboratory settings, it can be prepared via a Grignard addition of methyl magnesium bromide to 3-oxobutanoic acid, followed by oxidation to the ketone and finally a stereoselective reduction.

Physical properties include a melting point of approximately 30–32 °C and a slightly sour, aqueous solubility of about 1 g ⋅ 100 mL−1 at room temperature. The acid is soluble in ethanol, acetone and chloroform. Its pKa is around 4.6 for the carboxyl group and 13 for the hydroxyl group. It is a colorless liquid or solid, depending on the temperature, and possesses a mild, odorless flavour.

In biochemical contexts, the acid is an intermediate in the catabolism of certain amino acids and can be found in the metabolic profiles of organisms that undergo anaerobic glycolysis. While not widely used as a commercial chemical, its derivatives serve as precursors in the synthesis of certain pharmaceuticals and flavor compounds. Research into its role in metabolic pathways continues, particularly in studies of branched‑chain amino acid metabolism and the regulation of gluconeogenesis.