The role of different anions in ionic liquids on Pseudomonas cepacia lipase catalyzed transesterification and hydrolysis

Lipase Pseudomonas cepacia (PS) catalyzed transesterification of ethyl 3-phenylpropanoate with eleven alcohols was investigated in three ionic liquids [ILs], [Bmim]BF4, [Bmim]PF6, and [Bmim]Tf2N, consisting of an identical cation and different anions. The yields were higher in hydrophobic ILs [Bmim]Tf2N (55-96%) and [Bmim]PF6 (22-95%), than in hydrophilic [Bmim]BF4 (0-19%). The incubation of lipase PS in hydrophobic ILs for a period of 20-300 days at room temperature resulted in an increased yield of 62-98% in [Bmim]Tf2N and 45-98% in [Bmim]PF6, respectively. The lipase PS-hydrophobic IL mixture was recycled five times without any decrease in the yield of the products. In another set of experiments, the hydrolytic activity of the enzyme was determined after incubation in each of the three ILs and in hexane for 20 days at room temperature. It was found to be 1.8- and 1.6-fold higher in [Bmim]Tf2N and [Bmim]PF6, respectively, remained unchanged in [Bmim]BF4 and was 1.6 times lower in hexane as compared to the non-incubated enzyme. © 2008 Elsevier B.V. All rights reserved.