Enzyme-catalyzed Acylation of (R,S)-1-phenylethanol in 1-butyl-3-methylimidazolium Based Ionic Liquids

Muzafera Paljevac, Željko Knez, Maja Habulin*

University of Maribor, Faculty of Chemistry and Chemical Engineering, Smetanova 17, SI-2000 Maribor, Slovenia
* Corresponding author: E-mail: maja.habulin@uni-mb.si
Phone: +386 2 22 94 462, Fax: +386 2 25 27 774

Abstract
Ionic liquids represent an exciting new class of reaction solvents for catalysis, which have been used successfully for enzyme-catalyzed reactions. In present research, three different ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl)] amide, were synthesized. They were used as a reaction medium for enzyme-catalyzed acylation of (R,S)-1- phenylethanol with vinyl acetate. Mentioned enzymatic reaction was performed in a batch stirred-tank reactor in order to optimise different reaction parameters (biocatalyst concentration, temperature, ...). The influence of three different immobilized lipases on reaction performance was studied as well. The highest reaction rate and conversion of 49.7% after 5 h of reaction performance was achieved in the case when immobilized lipase Novozym 435 from Candida antarctica was used as a biocatalyst and hydrophilic ionic liquid 1-butyl- 3-methylimidazolium tetrafluoroborate as a solvent. Therefore, the optimization of different reaction parameters on lipase- catalyzed acylation of (R,S)-1-phenylethanol was carried out in 1-butyl-3-methylimidazolium tetrafluoroborate.

Keywords: Immobilized lipase, acylation, (R,S)-1-phenylethanol, ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate