Facile synthesis of fatty acid esters in high yields

The facile synthesis of esters by lipase-catalysed esterification of fatty acids and ethanol is demonstrated. Evaporation of the water generated in the reaction allowed the rapid production of esters of >99% yield in refluxing pentane or hexane. Water was trapped by condensing the refluxing vapor phase and passing it over activated molecular sieves in a reflux trap. High yields were rapidly obtained in synthesis of ethyl esters of oleic, linoleic, α-linolenic, and arachidonic acids without peroxidation of double bonds. The wax ester oleyl oleate was also synthesized rapidly with little peroxidation. A molar excess of 1.25 to 1.5 of ethanol allowed the most rapid ester synthesis. Synthesis of ethyl stearate was carried out on a preparative scale (50 g). Greater than 99% conversion was obtained in 50 min.