Enzymatic esterification of (-)-menthol with lauric acid in isooctane by sorbitan monostearate-coated lipase from Candida rugosa

Esterification of (-)-menthol and (±)-menthol with lauric acid in isooctane was successfully catalyzed by a commercial nonionic surfactant (sorbitan monostearate)-coated lipase from Candida rugosa (Lipase AY "Amano" 30) at the molar ratio of 1:1 andat 35°C using 1.5 g enzyme/g (-)-menthol and 0.1-g molecular sieves. After 1 h, molar conversion of (-)-menthol reached 81%. Equilibrium was reached after ca. 4 h, giving a (-)-menthol molar conversion of 94%. Under the same conditions, native lipase catalyzed the esterification of (-)-menthol and lauric acid to yield a molar conversion of 93% after 72 h. Coating the lipase with sorbitan monostearate increased the esterification rates of both (-)-menthol and (±)-menthol with lauric acid. After 6 h, the molar conversions of (-)-menthol and (±)-menthol were 94, and 62%, respectively.