Use of Solid Catalysts in Friedel-Crafts Acylation Reactions

To date, great efforts have been made by different research groups to achieve the goal of making the Lewis acid role catalytic in Friedel‐Crafts acylation. Different classes of materials have been studied and employed as heterogeneous catalysts of Friedel‐Crafts acylations: these include zeolites, (acid treated)metal oxides, and heteropoly acids already utilized in the hydrocarbon reactions. Furthermore, the application of clays, perfluorinated resinsulfonic acids, and supported (fluoro) sulfonic acids is the subject of intensive studies in this area. This review deals with the developments, mainly during the past decade, in the use of heterogeneous catalysts for Friedel‐Crafts acylation of aromatic compounds. The argument is organized in five sections, namely acylation of arenes, aromatic ethers, aromatic trioethers, phenolic substrates, and heterocycles. Focus is on the role played by the surface active sites in the activation of reagents as well as in the different modes of regioselectivity encountered in the acylation of arenes, aromatic ethers, and phenols.