Liquid 2-hydroxy-4-methylthiobutyric acid and process for the

Abstract

A process for the preparation of 2-hydroxy-4-methylthiobutyric acid having improved color, odor and lower viscosity. 2-hydroxy-4-methylthiobutyric acid which is also known as 2-hydroxy-4-(methylthio) butanoic acid, is hydrolyzed with sulfuric acid having an initial strength of between about 50% by weight and about 70% by weight on an organic-free basis, thereby producing an intermediate aqueous hydrolysis product solution containing 2-hydroxy-4-methylthiobutyramide. The 2-hydroxy-4-methylthiobutyramide is hydrolyzed with sulfuric acid having a strength of between about 30% by weight and about 50% by weight on an organic-free basis to produce an aqueous hydrolyzate containing 2-hydroxy-4-methylthiobutyric acid. The hydrolyzate solution is contacted with a substantially water-immiscible organic solvent in a liquid-liquid extraction system to produce an extract comprising the solvent and 2-hydroxy-4-methylthiobutyric acid transferred from the hydrolyzate. The acid product is then recovered from the extract.