Optical resolution of racemic 2-hydroxy octanoic acid using biphasic enzyme membrane reactor Original Research Article

A lipase-immobilized biphasic membrane reactor was applied for the optical resolution of racemic 2-hydroxy octanoic acid. Lipase from Candida rugosa or Pseudomonas cepacia was used as a biocatalyst, and three kinds of capillary membranes were employed as immobilization supports. The (S)-isomer of racemic 2-hydroxy octanoic acid methyl and butyl esters was preferentially hydrolyzed by both lipases. Immobilized P. cepacia lipase showed higher enantio-selectivity in biphasic membrane reactor than the native one did in emulsion stirred tank reactor, while immobilized C. rugosa lipase showed smaller enantio-selectivity than the native one. The use of butyl ester instead of methyl ester led to higher enantio-selectivity in C. rugosa lipase immobilized membrane reactor. In the membrane reactors with P. cepacia lipase immobilized, reaction rate and enantio-selectivity were affected by the types of membranes employed and the amount of enzyme loaded on the membrane. By use of biphasic membrane reactor with P. cepacia lipase immobilized, (R)-isomer and (S)-isomer of 2-hydroxy octanoic acid were obtained at the optical purity of 0.95 and 0.99 respectively.