OPTIMIZATION OF LIPASE-CATALYZED SYNTHESIS OF (Z)-3-HEXEN-1-YL ACETATE BY DIRECT ESTERIFICATION IN HEXANE AND A SOLVENT-FREE MEDIUM

The lipase from Candida antarctica immobilized on an acrylic resin (No vozym 435) was investigated for its use in the synthesis of (z)-3-hexe n-1-yl acetate by direct esterification in n-hexane and a solvent-free medium. A careful examination of major parameters (temperature, amoun t of lipase, substrates concentration, acid:alcohol ratio) established the suitability of Novozym 435 for the preparation of the title compo und. Under the same conditions, the lipase from Mucor miehei immobiliz ed on a microporous anion exchange resin (Lipozym IM) Sailed to produc e acetate in appreciable yield. In n-hexane at 70 degrees C in the pre sence of 2% (w/w reactants) of the lipase nod 1.5 mol l(-1) of substra te, the ester yield reached 94% in less than 27 h; moreover, the lipas e operated in the absence of solvent as well: 70% yield using 9% (w/w reactants) of lipase. This yield could be significantly improved (80-8 2%) by progressively adding a 50% excess of acetic acid to the mixture of Novozym 435 and (z)-3-hexen-1-ol. (C) 1995 Elsevier Science Inc.