METHOD OF PRODUCING METHIONINE Russian patent published in 2018 - IPC C07C319/20 C07C319/26 C07C319/28 C07C323/58 

FIELD: chemistry.

SUBSTANCE: according to the proposed method, carbon dioxide is loaded into an aqueous solution of potassium methioninate produced by hydrolyzing 5-(2-methylmercaptoethyl)hydantoin to precipitate crude methionine that is separated and purified. For purification, an aqueous solution of separated crude methionine is prepared and recrystallized. Herewith the solution, from which the recrystallization is carried out, contains a defoamer, potassium ions, and an additive for providing crystallization. The defoamer contains silicone oil, and the additive for providing crystallization is an anionic surfactant or a mixture of various anionic surfactants. Recrystallization is carried out by adding hot (60-110°C) methionine solution into the warm (35-80°C) suspension of methionine, the temperature of which is lower than the temperature of the added solution. During the addition, the temperature of the methionine suspension is maintained at 35 to 80°C. The additive for providing crystallization is one of the compounds represented by formulas 1-3, or a mixture thereof. In formulas 1-3, n is an integer from 1 to 12, M is sodium or potassium, R¹, R² and R³ are a linear, branched or cyclic, saturated or unsaturated C₈-C₂₀-alkyl group or an aryl group. R¹-O-SO₃M (formula 1); R²-O-(CH₂)_n-SO₃M (formula 2); R³-(OC₂H₄)n-O-SO₃M (formula 3).

EFFECT: method allows to produce methionine, which is easy to be filtered and has a high bulk density.

9 cl, 6 dwg, 5 ex