Transesterification of triacetin using solid Bronsted bases

This paper reports the results of an investigation into the use of solid Bronsted base catalysts as a potential alternative to homogeneous base catalysts in the transesterification of triacetin with small alcohols carried out under mild reaction conditions. Two catalysts with organic quaternary ammonium functionality (QN(+)OH(-)), a resin (A26), and a functionalized silica gel (QN(+)OH/SiO2), were used for the transesterification of triacetin with methanol (a model reaction), and their performance was studied in detail. Reactions were carried out in a well-mixed isothermal batch reactor at 60 degrees C. Both solid bases showed appreciable catalytic activity for the transesterification of triacetin conforming to the base strength of the active centers. Although the polymeric organic catalyst showed lower site activity, it was more stable during multiple reaction cycles (i.e., showed less deactivation) than the silica-supported catalyst and exhibited a higher total selectivity for glycerol for a given triacetin conversion. The effect of the support on the Bronsted base catalyzed transesterification is discussed, as is probable routes for silica-supported catalyst deactivation. (c) 2007 Elsevier Inc. All rights reserved.