Method for the production of 2-hydroxy-4-(methylthio)butyronitrile from 3-(methylthio)propanal and hydrogen cyanide

摘要

A method for the production of 2-hydroxy-4-methylthiobutyric acid by hydrolysis of 2-hydroxy-4-(methylthio)butyronitrile is provided. 3-Methylmercaptopropionaldehyde is reacted with hydrogen cyanide in the presence of a base as catalyst in a main reaction zone of the 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. The residual gaseous hydrogen cyanide is removed 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; and the gaseous hydrogen cyanide is further reacted with the 3-methylmercaptopropionaldehyde in the absorption and post reaction zone. A molar ratio of hydrogen cyanide to 3-(methylthio)propanal in the main reaction zone is from 0.98 to 1.03.

主权项

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.