Biotransformations in an Ionic Liquid Solvent System

VARIOUS BIOTRANSFORMATIONS IN AN IONIC LIQUID SOLVENT SYSTEM 

An IL solvent system is applicable to not only lipase but also other enzymes, though examples are still limited for hpase-catalyzed reaction in a pure IL solvent. But several types of enzymatic reaction or microhe-mediated reaction have been reported in a mixed solvent of IL with water. Howarth reported Baker s yeast reduction of a ketone in a mixed solvent of [hmim] [PFg] with water (10 1) (Fig. 16). Enhanced enantioselectivity was obtained compared to the reaction in a buffer solution, while the chemical yield dropped. 

Antibody-catalyzed aldol condensation was demonstrated in a [bmim][PFg] solvent system by Kitazume and co-workers (Fig. 17). They tested recyclable use of antibody catalyst in the solvent system and, very interestingly, found that the chemical yield was increased for the second cycle (89%) over the initial run (21%). 

Okrasa and co-workers reported an interesting combination reaction of glucose oxidase and peroxidase in a mixed solvent of [bmimJpFg] with water (Fig. 18). Asymmetric oxidation of sulfide was accomplished successfully in the reaction system.  

Griengl reported the first example of hydroxynitrile lyase-catalyzed cyanohydrin formation in a mixed solvent system of [bmim][BF4] and buffer (pH 3.7) (1 1) (Fig. 19). In the reaction, a mixed solvent system was essential, but excellent results were obtained. 

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