Lipase-catalyzed transesterification synthesis of citronellyl acetate in a solvent-free system and its reaction kinetics

The lipase-catalyzed citronellol synthesis of citronellyl acetate via transesterification was investigated in a solvent-free system. After screening several lipases, the lipase from Pseudomonas fluorescens was identified as the optimal enzyme for the system. The optimal reaction temperature was 40 °C. The external diffusion limitation could be greatly reduced by increasing the agitation speed to 200 rpm. A linear relationship between the initial reaction rate and an enzyme load of up to 6 mg mL−1 demonstrated that the internal diffusion limitations could be minimized. Substrate inhibition was absent when the substrate concentration was below 500 mmol L−1, but the experimental results indicated that the product inhibition effect should be considered. The results from the reaction kinetics analysis showed that the reaction obeys the ping-pong bi–bi mechanism that is inhibited by citronellyl acetate. Matlab was used to simulate the model parameters. The experimental values could be satisfactorily fitted to the simulated values with a relative error of 11.98 %.