Patent ID: 8754256

Claim:
A method of preparing L-arginine α-ketoglutarate 1:1, comprising the steps of: (a) providing a α-ketoglutaric acid aqueous solution and adding water to adjust concentration of the α-ketoglutaric acid aqueous solution, wherein the α-ketoglutaric acid aqueous solution is prepared and purified by the steps of: (a.1) mixing a dimethyl 2, 2-dichloroglutarate with a hydroxide solution at a second controlled temperature for 0.5-8 hours to form a first mixture, wherein the dimethyl 2, 2-dichloroglutarate is prepared by the steps of: (a.1.1) stirring methyl dichloroacetate and acrylic acid methyl ester at a first controlled temperature of 0-60° C.; (a.1.2) adding sodium methoxide slowly to form a first reaction mixture; (a.1.3) allowing reaction for a first controlled time of 1-4 hours at the first controlled temperature with stirring; (a.1.4) washing the first reaction mixture after step (a.1.3) twice, wherein 100-300 liter of water is added for each of the washing; and (a.1.5) separating organic phase from the first reaction mixture in step (a.1.4), and obtain the dimethyl 2, 2-dichloroglutarate through distillation under reduced pressure; (a.2) adding inorganic salt to the first mixture and stirring for 0.5-5 hours for precipitation of α-ketoglutarate salt; (a.3) filtering the α-ketoglutarate salt out, and adding water and inorganic acid to the α-ketoglutarate salt while stirring and adjusting pH thereof <4.5; (a.4) removing the inorganic salt through filtration to obtain a crude α-ketoglutaric acid aqueous solution; and (a.5) removing impurities from the crude α-ketoglutaric acid aqueous solution by passing the crude α-ketoglutaric acid aqueous solution through one of cation exchange resin and anion exchange resin to obtain a purified α-ketoglutaric acid aqueous solution; (b) adding solid L-arginine as raw materials to directly react with the purified α-ketoglutaric acid aqueous solution to form a reaction mixture, (c) allowing reaction of the reaction mixture at a first controlled temperature for a first controlled period of time; (e) obtaining a resulting L-arginine α-ketoglutarate 1:1 solution from step (d), wherein pH of the resulting L-arginine α-ketoglutarate 1:1 solution is approximately 3 to 4 when preparing L-arginine α-ketoglutarate 1:1; and (f) obtaining a final product of L-arginine α-ketoglutarate 1:1 from step (e) through spray drying.