Impacts of ionic liquids on enzymatic synthesis of glucose laurate and optimization with superior productivity by response surface methodology

As biosurfactants derived from naturally renewable resources, sugar fatty acid esters have broad applications in food, cosmetic and pharmaceutical industries. Glucose laurate was synthesized by a lipase-catalyzed acylation of glucose with vinyl laurate in ionic liquid (IL) systems. 16 ILs were screened for investigating the impact of the IL's compositions on both the solvent properties of the IL and the synthetic process. The conversions obtained in ILs showed a bell-shaped relationship with their log P values. ILs that carry hydrophobic cations and hydrophilic anions seemed to favor the sugar ester synthesis. 1-Hexyl-3-methylimidazolium trifluoromethylsulfonate ([HMIm][TfO]) was selected both as a pure solvent and as a co-solvent with 2-methyl-2-butanol (2M2B) for this application, and the influence of the affecting factors (such as reaction temperature, enzyme amount, molar ratio of the two substrates, and reaction time) has been studied. Response surface methodology (RSM) was applied to optimize the [HMIm][TfO]/2M2B bisolvent system, and an optimal productivity of 14.2 mmol/L/h was achieved, which is superior to other literature results. (C) 2015 Elsevier Ltd. All rights reserved.