Lipase-Catalyzed Oxidation of Cyclohexanone To Form ε-Caprolactone and Kinetic Modeling

The chemoenzymatic conversion of cyclohexanone to e-caprolactone (1.25 M) mediated by immobilized lipase from T. laibacchi was successfully achieved with a yield of 98.6%, which is much higher than that in previous studies. A proposed kinetic model consisting of two enzymatic reactions catalyzed by the lipase and one chemical reaction was developed, which fitted the experimental data very well. It was concluded that the enzymatic oxidation of ethyl acetate using urea hydrogen peroxide (UHP) to generate in situ peracetic acid mediated by the lipase may follow an irreversible ping-pong three–four mechanism with substrate inhibitions, which is proposed herein for the first time. Also, the oxidation of cyclohexanone to e-caprolactone by peracetic acid in a chemical fashion may follow a power law. Finally, the reaction of formed acetic acid with UHP to form peracetic acid catalyzed by the lipase may follow an irreversible ping-pong Bi–Bi mechanism with substrate inhibitions. Reaction kinetic data reveal that U...