LIPASE-CATALYZED SYNTHESIS OF MONOSTEAROYLGLYCEROL IN ORGANIC-SOLVENTS FROM 1,2-O-ISOPROPYLIDENE GLYCEROL

The lipase-catalyzed acylation of 1,2-O-isopropylidene glycerol was st udied. The products obtained were hydrolyzed to their corresponding 1- monostearoylglycerides. Different approaches were investigated, and fo r the transesterification of ethyl stearate with (rac)-1,2-O-isopropyl idene glycerol 1 in various organic solvents the highest initial rates were found in n-heptane and n-dodecane. The direct esterification of 1 with stearic acid gave the highest conversion (84%). Variation of th e alkyl residue of stearate led to a decrease in the initial rates in the order: ethyl --> methyl approximate to propyl --> butylstearate. A n enantioselective reaction was found for the faster reacting R-enanti omer in the transesterification of 1 with ethyl stearate resulting in 11%ee for the product. To elucidate the reasons for the low stereosele ctivity, reactions of R- and S-1,2-O-isopropylidene glycerol with ethy l stearate in n-heptane were carried out. The remaining activity of th e lipase was between 50 and 85% after 50 to 600 h reaction time.