METHOD FOR PREPARING METHIONINE Russian patent published in 2007 - IPC C07C319/20 C07C319/28 C07C323/58 

FIELD: organic chemistry, amino acids, chemical technology.

SUBSTANCE: invention describes a method of high volume density for synthesis of methionine. Method involves using a mixture comprising 3-methylmercaptopropionic aldehyde, hydrogen cyanide and carbon dioxide in the optional presence of water providing synthesis of 5-(2-methylmercaptoethyl)hydantoin and its conversion to methionine. Before passing carbon dioxide to a prepared mixture this aqueous mixture comprising compounds of the general formula: C_nH_2n+x-C=O-O-[CH₂-CH₂-O]_m-H (1) wherein symbols have the following values: n means a whole number from 9 to 19; m means distribution in the range from 1 to 10; x means 1, -1, -3, -5 wherein 2n + x is 1, not less, and additive (2) as modified cellulose is added to hydrolysis solution prepared from 5-(2-methylmercaptoethyl)hydantoin in the mass ratio from 1:10 to 10:1 and in the total amount from 5 to 5000 ppm as measured for methionine in solution, and methionine is precipitated from solution followed by its dissolving and recrystallization. Invention provides reducing foam formation in synthesis of methionine, improved form of its crystals based on addition of carbon dioxide in precipitation of methionine from solution prepared as hydrolysis product. The additive (1) elicits anti-foaming effect while simultaneous presence of component (2) doesn't show negative effect on anti-foaming effect.

EFFECT: improved method of synthesis.

11 cl, 2 tbl, 4 dwg, 3 ex