Polyethylene glycol400 laurate synthesized by immobilized lipase in a solvent-free system

Conditions for the esterification of polyethylene glycol400 (PEG400) with lauric acid by immobilized lipase from Candida sp. 1619 in a solvent-free system were investigated. The esterification degree was increased greatly through the dehydration that occurred during the reaction. When the amount of lauric acid added exceeded the stoichiometric amount the yield of product was further improved by fed-batch feeding of PEG400. In the reaction system that was composed of 5.0 mmol of lauric acid, 2.5 mmol of PEG400, 20 mg of immobilized lipase (200 u), 0.2 ml of water, at 40 degrees C shaken for 48 h in a 100-ml conical flask without a plug, the esterification degree of 98.9% was reached. When the amount of lauric acid used was increased to 60 mmol, the PEG400 in reaction system was completely esterified. The recovery yield of product was 95% by hexane extraction and the product was identified as diester by means of TLC.