Esterification of myristic acid in supercritical carbon dioxide

The esterification of myristic acid with ethanol was studied with a commercial lipase (crude Hog pancreas lipase, HPL). The reaction was investigated in solvent-free conditions and in two solvents: supercritical carbon dioxide (SCCO2) and acetonitrile. Conversions of up to 76% were obtained under solvent-free conditions while conversions of only up to 37 and 4% were obtained in SCCO2 and acetonitrile, respectively. However, for similar enzyme concentrations, 37% of the myristic acid was converted to ester in SCCO2 but only 4% was converted in acetonitrile and solvent-free conditions. Various parameters like temperature, water and ethanol concentrations that influenced the reaction were also investigated. Ethanol was found inhibitory for the reaction in SCCO2. Addition of water led to sharp reduction in the conversions of myristic acid.