Lipase-Catalyzed Transesterification between Tri-n-butyrin and Aliphatic Primary Alcohols in Neat

Abstract

A study was made of lipase-catalyzed transesterification between tri-n-butyrin (1) and aliphatic primary alcohols (2) (ROH : R=C6H13C11H23) in substrates to give the corresponding n-alkyl butyrates. Six out of thirteen lipases (C.c. : Candida cylindracea, P.f. : Pseudomonas fluorescens P.s. : Pseudomonas sp., P.c. : Penicillium cyclopium, P.r. : Penicillium requeforti and P.p. : Porcine pancreas) showed good reactivity. The addition of water increased and optimum rates were observed at 1.0, 0.8 and 0.4 vol% of water added for C.c., P.f. and P.s., P.p., and P.c. and P.r., respectively [in (1) containing 2 M (2), lipase=20 mg/mL-sub]. The lipases were classified into three types according to the manner in which they were affected by water. The reactivity of (2) was confirmed by the lipases, i.e., C8C10 and C9 alcohols gave maximum rates for C.c., P.f. and P.s., respectively. No significant change in rate could be detected for P.c., P.r., or P.p. lipase. Optimum rates were observed at 90, 60, 50 and 30 for P.f. and P.s., P.p., and P.c., C.c., and P.r. lipases, respectively. The addition of butyric acid caused no significant change in the rates. The thermal stability of Pseudomonas lipase in (1) was also examined.