ENZYMATIC ESTERIFICATION OF GLYCEROL .2. LIPASE-CATALYZED SYNTHESIS OF REGIOISOMERICALLY PURE 1(3)-RAC-MONOACYLGLYCEROLS

Regioisomerically pure 1(3)-rac-monoacylglycerols are conveniently prepared in high yields (>75%) and in multigram quantities by enzymatic esterification of glycerol in the presence of various lipases (Chromobacterium viscosum, Rhizopus delemar, Rhizomucor miehei) with a variety of different acyl donors, such as free fatty acids, fatty acid alkyl esters, vinyl esters and triacylglycerols, as well as natural fats and oils. All reactions are carried out in aprotic organic solvents with low water content, namely n-hexane, diethyl ether, tBuOMe or mixtures of these solvents. Essential for the success of there transformations were the following two factors. First, the creation of an artificial interphase between the solvent-immiscible hydrophilic glycerol and the hydrophobic reaction medium by its adsorption onto a solid support. Second, a facile system for the separation of the desired monoacylglycerol from the reaction mixture, coupled with the continuous recycling of acyl donor and undesirable by-products.