Lipase-mediated epoxidation of the cyclic monoterpene limonene to limonene oxide and limonene dioxide

Abstract

Limonene is an industrially interesting monoterpene that accumulates in bulk quantities as byproduct of the fruit juice industry. The corresponding epoxides are versatile synthetic intermediates and additives for the chemical industry. Due to a number of disadvantages of classical chemical epoxidation including serious safety issues and unwanted side-reactions, we here used a mild lipasecatalyzed chemo-enzymatic epoxidation system, with either free or different immobilized forms of Candida antarctica lipase B. Full limonene conversion (° 98%) was easily achieved at 40°C within less than 24 h. The enzymatic activities in the formation of limonene monoxide significantly varied from either 1-3.4 U/mgbiocatalyst at r.t. or from 1.7-4.9 U/mgbiocatalyst at 40°C. For the first time we showed that it is possible to generate high amounts of limonene dioxide (∼ 30% with CalB on carrier 350 at 40°C) using this mild lipase-mediated epoxidation method. Enzyme activities and limonene dioxide yields strongly depend on the nature of the selected enzyme carrier, the immobilization method and the reaction temperature. © 2012 Verlag der Zeitschrift fur Naturforschung.