Lipase‐catalyzed synthesis of lesquerolic acid wax and diol esters and their properties

Abstract

AbstractLesquerolic acid was and α,Ω‐diol esters were synthesized via immobilizedRhizomucor miehei lipase‐(Lipozyme) catalyzed esterification of lesquerolic acid and alcoholysis of lesquerella oil. For each wax ester synthesis, when alcohol substrate was present at a slight (ca. 20%) stoichiometric excess and water content was kept low, over 94% of the hydroxy acyl groups were esterified. The extent of reaction and the ratio of monoester to diester produced for α,Ω‐diol reactions was controlled by the solubility of diol in the medium. This latter quantity increased as alcoholysis proceeded due to the formation of partial glycerides and monoesters, which increased the polarity of the medium. Alcoholysis reactions were significantly slower when the medium diol content was above saturation. As the diol chainlength increased, diol solubilization decreased, the ratio of monoester to diester decreased, and the extent of hydrolysis increased. Alcoholysis reactions involving either fatty alcohols or diols suffered from acyl migration, which lowered the purity of lesquerolic acid esters. Several lesquerolic acid esters, synthesized on a preparative scale and purified via column chromatography, were evaluated for their properties: density, viscosity, and melting point. Potential applications for lesquerolic acid esters are discussed.