Study On The Synthesis Of Glycerol Carbonate Catalyzed By Candida Antarctic Lipase B

In this study, synthesis of glycerol carbonate from glycerol and dimethyl carbonate in THF catalyzed by Candida Antarctic lipase B (CALB) was studied. Meanwhile, much attention has been paid to get different glycerol carbonates.Four products were detected from the reaction mixture, i.e. 1-carbonate glycerol ester(monoglyceride), 4-hydroxymethyl-2-oxo-1,3-dioxolane(diglyceride), 4-(methoycarbon- yloxymethyl)-1,3-dioxolan-2-one and 2-oxo-1,3-dioxolane-5-methyl carbonate(triglyceride), while the diglyceride is the only final product reported in literature. Among the four products, the monoglyceride, 4-(methoycarbonyloxy methyl)-1,3-dioxolan-2-one and its isomer were converted to the diglycerides gradually and partially, which was not observed under same reaction conditions in literature.For the conversion of glycerol, with an initial water content of 8%, molar ratio of glycerol to dimethyl carbonate of 1:1, 60 oC, lipase loading of 3889 U/g dimethyl carbonate,0.05 g glycerol/mL THF, the highest glycerol conversion reached 45% at pH7 in 2 3h.To obtain the monoglyceride as the main product, with an initial water content of 8%, molar ratio of glycerol to dimethyl carbonate of 1:3, 55 oC, lipase loading of 1296 U/g dimethyl carbonate,0.05 g glycerol/mL THF, a yield of monoglyceride of 63% was achieved at pH7 in 2 h.The high polarity solvent such as DMF and DMSO can deactivate CALB under the reaction conditions; acetone can not make a good conversion of glycerol either. However, THF was found a suitable solvent to this reaction. The yield of diglyceride is 80% and the selectivity of diglyceride over 96% nearly when petroleum ether was used as the solvent.Aiming at to achieve more triglycerides, with an initial water content of 8%, molar ratio of glycerol to dimethyl carbonate of 1:10, 60 oC, lipase loading of 389 U/g dimethyl carbonate,0.05 g glycerol/mL THF, the highest yield of triglyceride of 52% was achieved at pH7 in 23 h.