Patent ID: 7223884
Filing Date: 2007-05-29
Classification: C07C

Abstract:
1. A process for producing methionine comprising hydrolyzing 5-(2-methylmercaptoethyl) hydantoin with at least one metal compound selected from the group consisting of metal hydroxides, metal carbonates and metal bicarbonates to give a methionine metal salt, neutralizing the methionine metal salt under the pressure of carbon dioxide gas to crystallize methionine, separating the resulting mixture into methionine and a filtrate and recycling the filtrate for the hydrolysis of 5-(2-methylmercaptoethyl) hydantoin, wherein the content of methionine oligomers and/or their metal salts in the aqueous solution used in the crystallization step is adjusted to 8% by weight or below in terms of methionine oligomers based on the amount of methionine produced.