ENZYMATIC POLYESTERIFICATION IN ORGANIC MEDIA .2. ENZYME-CATALYZED SYNTHESIS OF LATERAL-SUBSTITUTED ALIPHATIC POLYESTERS AND COPOLYESTERS

Enzymatic polymerization of hydroxyesters in organic media has been the subject of a previous and ongoing research in our laboratory. As part of that study, four epsilon-substituted-epsilon-hydroxyesters were synthesized, and then polymerized using crude porcine pancreatic lipase (PPL) in n-hexane. These lateral-substituted hydroxyesters polymerized enantio-selectively to produce optically active oligomers and a resolved optically active unreacted monomer. It was found that with increasing bulkiness of the lateral substituent, in the order Me < Et < Ph, the enzymatic reaction becomes slower, yet the enantioselectivity is higher. The lateral-substituted hydroxyesters were also copolymerized enzymatically with the more reactive linear methyl epsilon-hydroxyhexanoate. Optically active copolymers were obtained, higher in molecular weight than the analogous homopolymers. (C) 1993 John Wiley & Sons, Inc.