On the development of an integrated membrane process with ionic liquids for the kinetic resolution of rac-2-pentanol

A membrane bioreactor containing a supported liquid membrane based on ionic liquids was successfully applied to the kinetic resolution of rac-2-pentanol catalysed by a commercial immobilized Candida antarctica lipase B (Novozym 435). Variables affecting the performance of the above bioreactor were studied. First of all, six ionic liquids were tested for use as liquid membrane phase supported in a Nylon membrane for the selective transport of the compounds involved in the reaction. The most suitable liquid membrane phase for the selective separation of the target compounds was found to be [bmim+][BF4−]. The influence of the water content of the medium on the synthetic activity, selectivity and enantioselectivity of the enzyme was then analysed in order to establish the optimal amount of water. Finally, the integrated reaction/separation process for the resolution of rac-2-pentanol was carried out at the optimal conditions found, using vinyl propionate and vinyl butyrate as acyl-donors. The greatest efficiency was achieved with the longest vinyl ester, vinyl butyrate.