Resolution of 2-bromo-o-tolyl-carboxylic acid by transesterification using lipases from Rhizomucor miehei and Pseudomonas cepacia

Several lipases were screened for their ability to catalyze the enantioselective transesterification of 2-bromo-o-tolyl acetic acid. Amongst the preparations tested, the lipases from Rhizomucor miehei and Pseudomonas cepacia were selected. The best enantioselectivity was obtained with Rhizomucor miehei lipase immobilized on polypropylene (E = 11.3), which was more stereoselective than the free form. Hydrophobic solvents with log P higher than 2.5 were the most suitable giving the highest E-values. In addition, factors such as the water activity and the reaction temperature had little effect on the resolution of the racemic mixture. The selectivity of the enzymes with respect to the substrate was also only weakly affected by the structure of the leaving alcohol except in the case of the iso-propyl group, which causes high steric hindrance. Operating conditions under reduced pressure were defined to resolve the racemic mixture with immobilized Rhizomucor miehei lipase. (C) 2001 Elsevier Science Ltd. All rights reserved.