New method for preparation of D-valine

摘要

A method for preparing D-valine from L-valine by racemization and chemical resolution is presented. The resolving reagent, D-2, 3 -dibenzoyl tartaric acid was obtained by hydrolyzation of D-2, 3-dibenzoyl tartaric anhydride prepared by reaction of benzoyl chloride with D-tartaric acid. DL-valine was prepared by racemization of L-valine in the presence of aldehyde in a medium of acetic acid at 100 to 110 deg C for 3 h. In the presence of mineral acid, reaction of D-2, 3 -dibenzoyl tartaric acid with DL-valine formed diastreroisomeric salts at 84 to 95 deg C. Salt composed of D-2, 3 -dibenzoyl tartaric acid and D-valine precipitated when the diastreroisomeric salts mixtures were cooled to 15 deg C. The salt was reacted with base giving D-valine with yield of 70 percent to 80 percent and optical purity of over 98 percent.