Ultrasound-assisted enzymatic transesterification of methyl benzoate and glycerol to 1-glyceryl benzoate in organic solvent

The aim of this work is to report the enzymatic transesterification production of 1-glyceryl benzoate under ultrasound irradiation, using a commercial immobilized lipase, Novozym 435. Firstly, a preliminary evaluation was carried out at 2, 4 and 6 h, at constant temperature of 50 °C, methyl benzoate to glycerol molar ratio of 1:1 and 5.5 wt% of enzyme concentration. After analyzing the results obtained, the experimental design technique was used to evaluate the effects of temperature, substrates molar ratio, enzyme concentration, solvent volume and ultrasonic power on the 1-glyceryl benzoate production. The highest conversion, around 16%, was obtained at 65 °C, 1:1 of methyl benzoate to glycerol molar ratio, 15 wt% of enzyme concentration, 7 mL of solvent and 40% ultrasonic power in 4 h of reaction. A preliminary kinetic experiment carried out varying the enzyme concentration (15 and 20 wt%) keeping fixed the temperature at 35 °C, 1:1 of substrates molar ratio, 3 mL of solvent and 40% of maximum ultrasonic power led to lower (around 15% after 12 h of reaction) conversions compared to that achieved in the experimental design.