Enhancement of activity and selectivity in lipase-catalyzed transesterification in ionic liquids by the use of additives

✍ Scribed by Francisco J Hernández-Fernández; Antonia P de los Ríos; Manuel Rubio; Demetrio Gómez; Gloria Víllora

• Publisher: Wiley (John Wiley & Sons)
• Year: 2007
• Tongue: English
• Weight: 196 KB
• Volume: 82
• Category: Article
• ISSN: 0268-2575
• DOI: 10.1002/jctb.1730

✦ Synopsis

Abstract

BACKGROUND: Seven ionic liquids (ILs) based on 1‐alkyl‐3‐methylimidazolium cation in combination with hexafluorophosphate and bis{(trifluoromethyl)sulfonyl}imide anions were tested as reaction media for lipase‐catalyzed transesterification in low water conditions. With the aim of improving the activity and/or selectivity of the lipase, various treatments were applied to ionic liquid media such as equilibration with aqueous solutions of salts, NaHCO~3~ or Na~2~CO~3~, or the addition of a catalytic amount of a non‐reactive organic base to the reaction mixture, triethylamine.

RESULTS: The treated ionic liquids were shown to be excellent media for lipase‐catalyzed ester synthesis by transesterification compared with conventional organic solvents, such as n‐hexane. All treatments were found to enhance the synthetic activity of the enzyme, the best results being achieved with the addition of triethylamine. The addition of a catalytic amount of this base to the ILs resulted in a significant increase in both the synthetic activity and selectivity values. For instance, the synthetic activity in [emim^+^][TfN~2~^−^] was enhanced more than 12 times and the selectivity increased from 86% to 95% when triethylamine was used.

CONCLUSION: These treatments could be easy‐to‐use approaches to improve the efficiency of enzymatic reactions in ionic liquids when the reaction does not proceed smoothly. Copyright © 2007 Society of Chemical Industry