Stusy On Epoxidation Of A-pinene Catalyzed By Lipase

α-pinene epoxide is a valuable intermediate for fine chemical synthesis,under different reaction conditions,over two hundreds different products have been reported in literature.Many of the products have significant importance as high value chemicals for the flavor industry.Generally,a-pinene epoxide is synthesized chemically using various catalysts under extreme oxidizing conditions.In the last decades,"promiscuous" reaction of some immobilized lipase was used for epoxidation of some unsaturated fat oils and olefin show greater superiority.In this paper,to optimize the process,the reaction was cayyied out in 5-mL vials with seal covers under shaken,the immobilized lipase Novozym(?)435 as catalyst,fatty acid as oxygen carrier,H2O2 as oxygen source and toluene as solvent.Optimization results found that to improve the reaction yield,it is important to improve the reaction selectivity.When the reaction is carried out at 30℃ and 250rpm with 1M dodecanoic acid as oxygen carrier,wt30-%H2O2 as oxygen carrier,the selectivity of the reaction is maintained at around 100%,and after 7 hours,the reaction can obtaine a 95.7%yield of product.The reaction was also cayyied out in 500ml round-bottomed reaction flask equipped with a agitator,unexpected,the yield of a-pinene epoxide is about 45%,which is lower than in 5-mL vialsand the lipase inactivation rate is also faster.By analyzing the difference in mass transfer patterns of the two reaction methods,we designed a simple reactor that is able to simulate the shake flask reaction conditions.When the epoxidation reaction was carried out in this simple reactor under the optimize conditions,after 5h,the reaction reached nearly 93%of a-pinene epoxide.The perhydrolysis reaction is the rate-limiting step of the epoxidation reaction,after a kinetic study of perhydrolysis reaction,we found that the perhydrolysis competitive inhibition by H2O2,and with the increase of carbon chain length of fatty acid the Km decreases.When Lipase-OF and Lipase-MY were simply immobilized on commercial porous styrene-divinylbenzene beads MCI GEL CHP20P,they display excellent thermal and pH stability,and also had a high loading capacity.But the lipase preparations could not catalytic the epoxidation reaction.