Synthesis of glycerol monooctadecanoate from octadecanoic acid and glycerol.: Influence of solvent on the catalytic properties of basic oxides

The preparation of monoglycerides can be carried our in the presence of acid or basic catalysts. The use of basic catalysts could limit secondary reactions leading to product degradation. A comparison of solid basic catalysts (MgO, ZnO, Na2CO3) has shown that zinc oxide is one of the best catalysts in the esterification of glycerol with stearic acid (octadecanoic acid) since the usual bases favor soap formation (saponification). Moreover, the use of a well chosen solvent increases the activity and the monoglyceride selectivity of zinc oxide due to the homogenisation of the reaction mixture and the limitation of the thermal reaction. Finally these results show that the esterification rate is strongly dependent on both the catalyst and on the solubility-solvation of reagents and products. (C) 2000 Academie des sciences / Editions scientifiques et medicates Elsevier SAS.