the separator) in which the desired monoacylglycerols are separated at lower tem-
peratures.
A schematic representation of the equipment used in this process is shown in
Figure 16. Crucial to the success of this method is the choice of the solvent or sol-
vent mixture in which the desired, more polar 1(3)-sn-monoacylglycerols are less
soluble than all of the other products, at least at the low temperatures employed.
Thus, while the desired products precipitate in the cooled separator, all other pro-
ducts (as well as unreacted acyl donors) remain in solution and are fed back to the
reactor, which contains both the enzyme and the glycerol on the solid support. In this
way, high yields of monoglycerides may be obtained, using a variety of acyl donors.
The success of the method was demonstrated with numerous acyl donors, such as
free fatty acids, fatty acid methyl esters and vinyl esters (Figures 17–19). Synthetic
triglycerides and natural fats and oils may also be used (see below). Moreover, the
method is not limited to natural fatty acids, as unnatural fatty acids may also be used.
110 6 Lipase-Catalyzed Synthesis of Regioisomerically Pure Mono- and Diglycerides
Figure 17. Regioisomerically pure 1(3)-sn-monoglycerides by lipase-catalyzed esterification of gly-
cerol.
Figure 18. Regioisomerically pure 1(3)-sn-monoglycerides by lipase-catalyzed transesterification of
glycerol.
Figure 19. Regioisomerically pure 1(3)-sn-monoglycerides by lipase-catalyzed irreversible transeste-
rification of glycerol.