| abstract |
(57) [Summary] (Revised) [Objective] To provide a method for producing methionine which produces less impurities and less waste methionine and less potassium bicarbonate to prevent their accumulation. [Structure] 5- (β-methylmercaptoethyl) -hydantoin is hydrolyzed in the presence of an alkali metal carbonate and / or bicarbonate, and the solution is neutralized with carbon dioxide to crystallize methionine, and after separation In the method for producing methionine, wherein the filtrate of (1) is recovered in the hydrolysis step of 5- (β-methylmercaptoethyl) -hydantoin, 3-methylmercaptopropionaldehyde is treated with at least one of potassium carbonate, potassium bicarbonate and potassium hydroxide as a catalyst. A method using 5- (β-methylmercaptoethyl) -hydantoin obtained by converting 3-methylmercaptopropionaldehyde cyanohydrin thus obtained into cyanohydrin with hydrocyanic acid to hydantoin with carbon dioxide and ammonia. |