Microfluidic biocatalysis enhances the esterification of caffeic acid and methanol under continuous-flow conditions

BackgroundMethyl caffeate is an important intermediate for the synthesis of other caffeate esters, but its industrial production via enzymatic esterification in a batch reactor is hindered by a long reaction time (9 h). To develop a rapid process for the high-yield production of methyl caffeate, a two-piece continuous-flow poly(dimethylsiloxane) microreactor with a sandwich-like microchannel structure was designed for the esterification of caffeic acid and methanol catalyzed by Novozym 435 in [Bmim][Tf2N]. RESULTSA maximum yield of 98.45% was achieved in a short period of time (2.5 h) in the microreactor at a flow rate of 2 mu L min(-1), and the reaction temperature was reduced from 75 degrees C to 70 degrees C compared with the batch reactor. The kinetic constants K-m and V-m/K-m(app) were 0.76 times lower and 282.08 times higher, respectively, than those in the batch reactor. Immobilized lipase could be reused at least 23 times without losing catalytic activity. CONCLUSIONThe use of a continuous-flow packed-bed enzyme microreactor is an efficient method to produce methyl caffeate. (c) 2015 Society of Chemical Industry