Enzymatic Synthesis Of Sucrose-6-Ester In Non-Aqueous Medium

Lipase-catalyzed regioselective acylation of sucrose in non-aqueous medium was researched in this paper. Two substances, 6-O-lauroylsucrose and sucrose-6-oleate,were synthesized.In this thesis, the study includes four aspects.First, the chemo-enzymatic synthesis of 6-O-lauroylsucrose was researched. Synthesizing sucrose-6-acetate by chemical way and purifying it, and then reacted with ethyl laurate by enzymatic catalysis. Many kinds of factors were studied. Under the best conditions, a sucrose conversion of 84.3% to sucrose-6-acetate, a sucrose-6-acetate conversion of 25.2% to 6-O-lauroylsucrose.Second, enzymatic transesterification synthesis of 6-O-lauroylsucrose in organic solvent was studied. Parameters such as lipase, solvent, molecular sieves, enzyme concentration, substrate concentration and temperature were studied. Under the optimized conditions, a sucrose conversion of 97.2%to 6-O-lauroylsucrose.Third, optimizing the synthesis of sucrose-6-oleate varying acyl donor, molecular sieves, temperature, the molar ratio sucrose/oleic anhydride, and the enzyme content. Under the best conditions, a sucrose conversion of 83.7% to sucrose-6-oleate was achieved.Fourth, a study on the kinetics of the esterification of sucrose and oleic anhydride was conducted. The fact that effect of the substrate concentration on initial rate of the reaction followed Michaeles-Menten equation suggests that the reaction agrees with the Ping-Pong Bi Bi mechanism. Inhibition by excess of oleic anhydride has been identified. The kinetic constants have been calculated for the reaction in the absence of any significant external diffusion limitations.