Patent ID: 7635787
Filing Date: 2009-12-22
Classification: C07C

Abstract:
1. A process for producing methionine comprising the step of: reacting methyl mercaptane with acrolein to obtain 3-methylmercaptopropionaldehyde, subjecting 3-methylmercaptopropionaldehyde to cyanhydrination with hydrogen cyanide to obtain 3 -methylmercaptopropioncyanhydrin, subjecting 3 -methylmercaptopropioncyanhydrin to hydantoination using carbon dioxide and ammonia to obtain 5-(β-methvlmercaptoethyl)-hydantoin, and hydrolyzing 5-(β-methylmercaptoethyl)hydantoin in the presence of an alkali, wherein a concentration of hydrogen sulfide is lowered to 5 ppm or less in a solution used for hydrolysis comprising 5-(β-methylmercaptoethyl)hydantoin and the alkali by at least one of the following methods: