Effect of water activity on the lipase catalyzed esterification of geraniol in ionic liquid [bmim]PF 6

• Published in: Biotechnology and Bioengineering
• Main Authors: Barahona, Donifan, Pfromm, Peter H., Rezac, Mary E.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2005
• Subjects: Antarc*; Antarctica
• Online Access: http://dx.doi.org/10.1002/bit.20723; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fbit.20723; https://onlinelibrary.wiley.com/doi/pdf/10.1002/bit.20723

Abstract Enzymatic reactions in non‐aqueous media have been shown to be effective in carrying out chemical transformation where the reactants are insoluble in water or water is a byproduct limiting conversion. Ionic liquids, liquid organic salts with infinitesimal vapor pressure, are potentially useful alternatives to organic solvents. It is known that the thermodynamic water activity is an important variable affecting the activity of enzymes in non‐aqueous solvents. This study investigated the influence of water activity on the esterification of geraniol with acetic acid in ionic liquid [bmim]PF 6 catalyzed by immobilized Candida antarctica lipase B. The conversion of geraniol in [bmim]PF 6 was significant although the reaction rate was slower than in organic solvents. The profile of initial reaction rate‐water activity was determined experimentally, and differed from the data reported for other non‐aqueous solvents. A maximum in the initial reaction rate was found at a w = 0.6. The pseudo reaction equilibrium constant, K x , was measured experimentally for the reaction. The average value of K x in [bmim]PF 6 was 12, 20‐fold lower than the value reported for the same system in hexane. © 2005 Wiley Periodicals, Inc.