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

Several lipases were screened for their ability to catalyze the enantiosele ctive transesterification of 2-bromo-o-tolyl acetic acid. Amongst the prepa rations tested, the lipases from Rhizomucor miehei and Pseudomonas cepacia were selected. The best enantioselectivity was obtained with Rhizomucor mie hei lipase immobilized on polypropylene (E = 11.3), which was more stereose lective 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 s uch 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 caus es high steric hindrance. Operating conditions under reduced pressure were defined to resolve the racemic mixture with immobilized Rhizomucor miehei l ipase. (C) 2001 Elsevier Science Ltd. All rights reserved.