Patent ID: 9133113
Filing Date: 2015-09-15
Classification: C07C

Abstract:
1. A process for producing 2-hydroxy-4-methylthiobutyric acid, the process comprising: hydrolysis of 2-hydroxy-4-(methylthio)butyronitrile to obtain the 2-hydroxy-4-methylthiobutyric acid; wherein the 2-hydroxy-4-(methylthio)butyronitrile is obtained by a process comprising: reacting 3-methylmercaptopropionaldehyde with hydrogen cyanide in the presence of a base as catalyst in a main reaction zone of a multizone reactor to form a reaction mixture comprising the 2-hydroxy-4-(methylthio)butyronitrile, unreacted 3-methylmercaptopropionaldehyde, the catalyst and residual amounts of gaseous hydrogen cyanide; removing the residual gaseous hydrogen cyanide from the main reaction zone to an absorption and post-reaction zone of the reactor which comprises a mixture of 3-methylmercaptopropionaldehyde and the catalyst; further reacting the gaseous hydrogen cyanide with the 3-methylmercaptopropionaldehyde in the absorption and post-reaction zone; and removing the 2-hydroxy-4-(methylthio)butyronitrile from the multizone reactor.