Experimental Study On Synthesis Of ?-caprolactone By Immobilized Enzyme And Its Kinetic Model

As an important intermediate compound,how to efficiently synthesize epsiloncaprolactone is of great significance to reduce the production cost.In this paper,starting from cyclohexanone,a series of single-factor experiments are used to determine the optimal reaction conditions for the chemical enzymatic synthesis of epsiloncaprolactone,and it is concluded that the reaction system consists of two enzymatic reactions and one chemical reaction.Under optimal conditions,the yield and concentration of epsilon-caprolactone are 98.6% and 1.23mmol/ml,which is much higher than other studies.In addition,the kinetic model of the reaction is also established in this paper.According to the kinetic model established,the reaction mechanism of each step is as follows: Using urea hydrogen peroxide as the oxidant,immobilized lipase catalyzed the reaction of in situ hydrolysis of ethyl acetate into peracetic acid.The reaction mechanism is an irreversible ping-pong three-four mechanism with substrate inhibition,which is obtained by adjusting and modifying the double substrate dynamics model;The reaction mechanism of peroxyacetic acid chemical oxidation of cyclohexanone to ?-caprolactone is a power-law mechanism;Immobilized lipase catalyzes the reaction of acetic acid produced in the previous step with urea hydrogen peroxide to produce peracetic acid,which belonges to the irreversible ping-pong mechanism with substrate inhibition.The reaction kinetics data shows that the model fitted well with the experimental data,and urea hydrogen peroxide and acetic acid may have strong substrate inhibition,while peracetic acid does not have product inhibition.It is reasonable to use the simple exponential equation as the model of lipase deactivation.