Microwave-assisted lipase-catalyzed synthesis of polyethylene glycol stearate in a solvent-free system

Polyethylene glycol stearate, a condensation esterification product of stearic acid and polyethylene glycol 600, was widely applied in the biomedical and healthcare industries. The current work focuses on the enzymatic synthesis of PEG stearate using CALB_ex10000, a commercial Lipase enzyme in solvent-free conditions using microwave irradiation. The influence of various reaction parameters such as temperature, molar ratio of reactants, and enzyme loading was studied to obtain the highest conversion. Maximum conversion of 85% was attained under molar ratio 1:1 (PEG 600 to stearic acid using 0.7% (w/w) enzyme loading at 60 ?°C of temperature in 70 ?min of reaction time. Further, the thermodynamic parameters were analyzed and compared with the conventional and ultrasound-assisted synthesis of PEG stearate. The enzyme was recycled up to 5^th cycle giving more than 35% of the initial activity.