General Papers ARKIVOC 2015 (vii) 1-9 Page 1 © ARKAT-USA, Inc. Friedel-Crafts acylation reaction catalyzed by silica supported sulfonic acids: synthetic aspects and limitations Calogero Giancarlo Piscopo (*), Giovanni Maestri, Emanuele Paris, Veronica Santacroce and Raimondo Maggi “Clean Synthetic Methodology Group”, Dipartimento di Chimica dell’Università, Parco Area delle Scienze 17A, I 43124 Parma, Italy E-mail: gc@ict.fhg.de DOI: http://dx.doi.org/10.3998/ark.5550190.p009.086 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. Keywords: Friedel-Crafts acylation, supported catalysts, sulfonic acids, anhydrides, anisole Introduction Since the first paper reported by Friedel and Crafts the acylation of aromatics has undoubtedly become one of the most investigated synthetic reactions. 1, 2 The considerable practical value of the aromatic ketones pushed indeed a great interest towards the study of electrophilic acylation and the optimization of related synthetic processes. 3 These products are particularly interesting building blocks for fragrance and pharmaceutical industries. 4, 5 Electrophilic acylation reactions are usually catalyzed by Lewis acids (ZnCl 2 , AlCl 3 and FeCl 3 ) or strong protic acids (HF and H 2 SO 4 ). The use of Lewis acids or corrosive mineral acids is however associated with a great number of environmental and economic issues. In most cases, reactions require stoichiometric amounts of catalyst and troublesome work-up procedures. Moreover these processes ultimately release a huge quantity of anions (especially chlorides) in aqueous medium. For these reasons, during the past decade, the development of more eco-compatible Friedel-Crafts acylation reactions has become a fundamental goal of green chemistry. 6