Hydroxynitrile immobilization

By screening a variety of lipases in organic solvent for their ability to acylate the racemic hydroxynitrile with succinic anhydride, Novozym 435 was found to yield the best results, affording product in 94-95 % ee at conversions of 47 9 % (Scheme 1.34). After optimization, the reaction was successfully run at 22 kg scale. The immobilized catalyst could be easily isolated by filtration and reused. 

Nippon Shokubai Kagaku Kogyo disclosed a complementary process for the synthesis of optically active cyanohydrins. (S)-hydroxynitrile lyase derived from plants like Euphorbiaceae, Gramineae, and Olacaceae could successfully be applied to synthesize 99.9% optically active (S)-mandelonitrile (S)-175 [147]. The enzymes showed high absorption ratios when immobilized on porous inorganic material such as ceramics, silica, alumina, or silica/alumina zeolithes and were also used for the synthesis of other cyanohydrins. 

F.L. Cabirol, U. Hanefeld, Immobilized Hydroxynitrile Lyases for Enantioselective Synthesis of Cyanohydrins Sol-Gels and Cross-Linked Enzyme Aggregates, Adv. Synth. Catal. (2006)... 

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