Synthesis of (Z)-3-hexen-1-yl butyrate in hexane and solvent-free medium using Mycor miehei and Candida antarctica lipases

(Z)-3-Hexen-1-yl butyrate is an important flavor and fragrance compound as it represents the model of a natural herbaceous (green) note. Two immobilized lipases from Mucor miehei (Lipozym IM) and from Candida antarctica (Novozym 435) were investigated for their use in the synthesis of (Z)-3-hexen-1-yl butyrate by direct esterification in n-hexane. To determine optimal conditions for esterification, we examined the following parameters: temperature, amount of lipase, acid/alcohol ratio, and absence of solvent. In n-hexane, bioconversion yields reached 95 (after 4 h) and 92% (after 6 h) for, respectively, Lipozym IM [17 (w/w reactants)] and Novozym 435 [2% (w/w reactants)]. In the absence of solvent, at 60 degrees C, Novozym 435-catalyzed esterification afforded the title compound in 80% yield. Up to 250 g (in hexane) and 160 g (without solvent) of ester were easily prepared, in a single operation, at a laboratory scale, in few hours, using 2% (w/w reactants) lipase.