p-Sulfonic acid calix[4]arene-functionalized alkylbridged organosilica in esterification reactions

J. V. DE ASSIS; P. A. S. ABRANCHES; I. B. BRAGA; O. M. P. ZUÑIGA; A. G.SATHICQ; G. P. ROMANELLI; A. G. SATO; S. FERNANDES

RSC

Royal Society of Chemistry

Año: 2016 vol. 6 p. 24285 - 24289

Two new p-sulfonic acid calix[4]arene- and p-sulfonic acid calix[6]arene-functionalizedorganosilica have been synthesized using the sol-gel method and applied as heterogeneouscatalysts in esterification reactions. The catalytic performance was evaluated using theesterification of carboxylic acids with ethanol, and good catalytic activity (i.e., 55-88%) wasobserved under the optimum reaction conditions. This study reports the first promisingexample of successful employment of calix[n]arenes as a heterogeneous catalyst forcatalytic esterification. The catalyst was easily separated by filtration and reused five timeswithout any significant loss of activity.