| Two kinds of miscible organic solvents with obvious discrepancy inpolarity were mixed at different mole proportions to create a series ofbinary solvent mixtures with different logP values. Lipase-catalysedesterification between 1-butanol and lauric acid in such binary solventmixtures as well as singular solvents with corresponding logP valueswere comparatively investigated. The variation of enzyme activity alongwith the decrease of solvent's polarity in solvent mixtures and singularsolvents respectively were compared, and different variation tendencieswere observed. A rationale based on the effects of the mix of solvents onthe thermodynamic activities of reactants and the activation energies ofreactions is proposed to explain the phenomena observed.On the other hand, there are numerous definite advantages ofconducting enzymatic conversions in ionic liquids (ILs) over intraditional organic solvents. So, a sort of hydrophobic ionic liquidbmimPF6 was synthesized and consequentially treated as reactionmedium for the lipase-catalysed regioselective acylation of pyridoxine.Substrate conversion and regioselectivity were estimated by the analysisof liquid chromatography equipped with a C18 inversed phasechromatographic column. Effects of various reaction parameters, such astype of solvent and acyl donor, enzyme loaded, water activity, time andtemperature, on the substrate conversion as well as regioselectivity werestudied. Ionic liquid bmimPF6 was found to be the most efficient solvent.Acetic anhydride proved to give better conversion and regioselectivitycompared to other acyl donors. Substrate conversion of 89.97% andregioselectivity of 93.43% were about to be obtained as long as optimizedreaction parameters were conducted.
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