Abstract: The effects of pH, temperature, mol ratio of 3,4-dimethyl-benzenesulfonic acid to L-leucine and NH4Cl concentration on the L-leucine precipitation yield by reacting with 3,4-dimethyl-benzenesulfonic acid were investigated. The pH value must be kept lower than 1.5, the optimal mol ratio of 3，4–dimethyl-benzenesulfonic acid to L-leucine was 3∶1. A low temperature was favorable for precipitation, preferably 0C.The yield decreased with the increase of NH4Cl concentration. L-leucine was separated from pig blood hydrolysate after removal of acid, and the precipitation rate was 90.62%. The L-leucine after refinement was in agreement with the standard of Pharmacopoeia of the People’s Republic of China (2000 edition, the second section)。

摘要： 考察了pH值、邻二甲苯–4–磺酸与L–亮氨酸的物质的量比、氯化铵浓度和温度等因素对邻二甲苯–4–磺酸反应沉淀L–亮氨酸的影响。结果表明：邻二甲苯–4–磺酸沉淀L-亮氨酸的适宜pH值为不高于1.5；邻二甲苯–4–磺酸与L-亮氨酸的最适物质的量比为3∶1；溶液中氯化铵浓度增大使L–亮氨酸的沉淀率缓慢下降；温度升高L–亮氨酸的沉淀率迅速降低，反应应于低温下进行，实际生产中可选择在0 ℃。按上述最佳工艺条件从除酸后猪血粉水解液中提取L–亮氨酸，沉淀率达到90.62%，经精制L-亮氨酸产品达到《中华人民共和国药典》(2000年版二部)的标准。