Process for the preparation of hydroxymethylthiobutyric acid

摘要

A process for hydrolyzing 2-hydroxy-4-methylthiobutyronitrile with sulfuric acid, characterised in that a molar quantity of sulfuric acid of between 0.6 and 0.88 relative to the 2-hydroxy-4-methylthiobutyronitrile is used. In a first step, the hydration of 2-hydroxy-4-methylthiobutyronitrile to 2-hydroxy-4-methylthiobutyramide is carried out with concentrated sulfuric acid in the presence of a water to 2-hydroxy-4-methylthiobutyronitrile molar ratio of between 1 and 3 at a temperature of less than or equal to 60oC. In a second step, the hydrolysis of 2-hydroxy-4-methylbutyramide to 2-hydroxy-4-methylthiobutyric acid is carried out in the presence of an additional quantity of water.