PURPOSE: Optically active mandelic acid is allowed to act on DL-phenylalanine and the resultant complex is resolved utilizing solubility difference to permit optical resolution of DL-phenylalanine in high yield and high purity.
CONSTITUTION: Optically active mandelic acid is allowed to act on DL-phenyl- alanine in a solvent such as water or methanol to form 2 kinds of diastereomer complexes. Then, cooling or other operations are effected to crystallize out a hard-soluble complex and the solid is separated from the liquid phase to obtain L-phenylalanine; L-mandelic acid or D-phenylalanine: D-mandelic acid. The resultant complex is decomposed with a mineral acid and the formed mandelic acid is extracted with an organic solvent, then the aqueous phase is neutralized with an alkali to precipitate optically acitve phenylalanine. Direct optical resolution can be effected in high yield and high purity without formation of DL-phenylalanine derivatives.
FUJII HIROSHI
NOHIRA HIROYUKI
