Catalytic processes in the chemistry of lactic acid and PLLA: Enzymatic stereoselective alcoholysis of rac-lactide

Abstract

The preparation of the enantiomerically pure (R,R)-lactide (>99%ee) on the gram scale by alcoholysis of rac-lactide in the presence of Amano lipase PS is described. The synthesis of enantiopure lactide by this method is advantageous over traditional preparation via thermal tin-catalysed cyclisation of corresponding oligolactic acids, since the reaction temperature are much lower. That results that no meso-lactide is formed. The alcoholysis of rac-lactide with n-BuOH was studied in the presence of various enzymes in different solvent systems. The kinetic study of the alcoholysis of rac-lactide in the presence of CALB was performed.