DL-苯丙氨酸合成工艺改进

Improved Method for Synthesis of DL-Phenylalanine

对DL-苯丙氨酸合成方法进行改进。以水为溶剂,乙醇胺为催化剂,将苯甲醛与海因经Knoevenagel缩合反应制得亚苄基海因,收率为90.1%;m(亚苄基海因):m(反应体系总质量)=10:1,在V(3mol/L NaOH水溶液):V(甲醇)=1:1,反应温度25℃下,以m(亚苄基海因):m(雷尼镍)=10:1为催化剂,氢气压力为200kPa,反应20h,获得苄基海因,收率为90.6%;经碱水解后得到DL-苯丙氨酸,收率为85.0%;三步反应总收率为69.4%。雷尼镍催化剂回收后,重复使用3次,反应收率无明显下降。

The synthesis of DL- phenylalanine comprises a three- step sequence using hydantoin and benzaldehyde as raw materials. A catalytic system used for Knoevenagel condensation of benzaldehyde and hydantoin was developed with yield 90.1%, in which, ethanolamine was used as catalyst and water was used as the condensation solvent. The yields of 5 - benzylidenehydantion is hydrogenated to 5 - benzylhydantoin with yield 90.6 % at gage pressure 200kPa with Raney nickel in alkaline media. The benzylhydantoin is hydrolyzed by using dilute caustic to DL - phenylalanine with yield 85.0%. The total yield of the three - step reaction was 69.4%. The catalyst can be easily recovered and reused four times without noticeable decrease of the catalytic activity.