NEAR-QUANTITATIVE PRODUCTION OF FATTY-ACID ALKYL ESTERS BY LIPASE-CATALYZED ALCOHOLYSIS OF FATS AND OILS WITH ADSORPTION OF GLYCEROL BY SILICA-GEL

A simple solution to the problem of incomplete reaction in lipase-catalyzed alcoholysis of triacylglycerol oils has been found. When immobilized Mucor meihei lipase was used to catalyze the reaction of tallow with three molar equivalents of butanol, the yield of butyl esters did not exceed 70% (w/w). If silica gel was added to the reaction mixture, it adsorbed the glycerol produced during the reaction and the yield increased to up to 98%. The optimum amount of silica gel was 1.25 weight equivalents to the glycerol produced. Other adsorbents were tested, e.g., cellulose, starch, charcoal, and celite, but none was as effective as silica gel. A variety of fats and oils could be used and all gave yields over 90%. Aliphatic alcohols varying in polarity between methanol and dodecanol also gave yields over 90%, although the highest yields were obtained from the most hydrophobic alcohols. The reaction could be carried out by circulating the reaction mixture through columns of enzyme and silica gel. Dehydration of the reaction mixture, and hence of the enzyme, by the silica gel caused loss of activity during repeated reuse of the enzyme. This problem could be minimized by increasing the water content of the initial reaction mixture.