Friedel-Crafts acylation reaction catalyzed by silica supported sulfonic acids: synthetic aspects and limitations

Abstract

The Friedel-Crafts acylation of anisole with acetic anhydride could be efficiently catalyzed by suitable silica-supported sulfonic acids. In particular, by using silica supported 4-ethylphenylsulfonic acid as catalyst it was possible to apply the synthetic procedure to different aliphatic anhydrides and aromatic compounds. It has been observed that the effect of the length of the alkyl chain of the anhydride is quite significant. Moreover, some attempts to regenerate the solid catalyst have been also discussed.

Acid properties of organosiliceous hybrid materials based on pendant (fluoro)aryl-sulfonic groups through a spectroscopic study with probe molecules

“…Sulfonic acids are one of the many functional groups that have been used to prepare silica based heterogeneous organocatalysts baring strong acid sites 18 for carrying out esterification of fatty acids 19 , acetalization reactions 20 , acetal hydrolysis Please do not adjust margins Please do not adjust margins activity of sulfonic acids has been studied and industrially exploited for several decades. For example, propyl-and arylsulfonic acids were supported onto amorphous silica and their activity was compared in the reaction of anisol with acetic anhydride 22 , showing a beneficial effect of having the sulfonic group bounded to an aromatic ring. An even more representative example of the effect of the chemical makeup of the sulfonic acid on its catalytic activity are fluorinated alkylsulfonic acids [23][24][25][26] .…”