The present invention provides crystals of L-phenylalanine monomethyl sulfate which have low solubility compared to L-tyrosine and D-phenylalanine. The L-phenylalanine monomethylsulfate crystals are obtained by subjecting a solution containing monomethyl sulfuric acid and phenylalanine to crystallization.
Further, the present invention also provides a process for recovering L-phenylalanine from a water layer by neutralizing the esterified reaction, extracting an ester of L-phenylalanine therefrom with an organic solvent, and recovering remaining L-phenylalanine in the water layer as L-phenylalanine monomethylsulfate. L-phenylalanine monomethyl sulfate is obtained by esterifying L-phenylalanine and methanol in the presence of sulfuric acid, neutralizing the esterified solution with a base in the presence of water, extracting the produced L-phenylalanine methyl ester from the neutralized solution with an organic solvent, and then crystallized the resultant water layer under acidic condition.
本发明提供了与
L-酪氨酸和
D-苯丙氨酸相比溶解度较低的
L-苯丙氨酸单甲基
硫酸盐晶体。
L-苯丙氨酸单甲基
硫酸盐晶体是通过将含有单甲基
硫酸和苯丙
氨酸的溶液进行结晶而获得的。
此外,本发明还提供了一种从
水层中回收
L-苯丙氨酸的工艺,方法是中和酯化反应,用有机溶剂提取其中的
L-苯丙氨酸酯,并以
L-苯丙氨酸单甲基
硫酸盐的形式回收
水层中剩余的
L-苯丙氨酸。
L-苯丙氨酸单甲酯
硫酸盐是通过在
硫酸存在下将
L-苯丙氨酸和
甲醇酯化,在
水存在下用碱中和酯化溶液,用有机溶剂从中和溶液中萃取生成的
L-苯丙氨酸甲酯,然后在酸性条件下将生成的
水层结晶而得到的。