Ionic Liquids as Media for Enzymatic Transformations

Although enzymes function admirably in water (their natural medium), some reactions cannot easily be performed in water owing to insolubility of hydrophobic reactants or equilibrium limitations, e.g., in esterifications and amidations. 

Impurities, such as water, halides, unreacted organic salts, and organics, easily accumulate in ionic liquids [15] and may influence their solvent properties [3, 16] and/or interfere with the biocatalyst. For example, small amounts of chloride ion caused a severe deactivation of two lipases [17]. The irreproducibility of some early 

Organic Synthesis with Enzymes in Non-Aqueous Media. Edited by Giacomo Carrea and Sergio Riva Copyright 2008 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-31846-9 

1-alkyl-3-methyl- 1,4-dialkyl- tetraalkyl- tetraalkyl-imidazolium pyridinium ammonium phosphonium 

The miscibility of ionic liquids with water varies widely and unpredictably. [BMIm][BF4] and [BMIm][MeS04] are water-miscible, but [BMIm][PF6] and 

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When the water-miscible ionic liquid [MMIM][MeS04] was used as a neat medium for the enzymatic transformations, however, poorer performance was observed. For the kinetic resolution of mc-l-phenylethanol by transesterification with vinyl acetate with a set of different lipases dispersed in the pure ionic liquid, it was found that [MMIM][MeS04] was among the poorest media for the enzymes (291). It has been recognized that some water-miscible ionic liquids in the pure form are denaturants (27), but, when they are used in the presence of excess water, their tendency to... 

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