Friedel-Crafts Acylation of Aromatic Ethers Using Zeolites

Friedel-Crafts Acylation of Aromatic Ethers Using Zeolites 

The Friedel-Crafts reaction and the related Fries rearrangement of aromatics are the most important methods in organic chemistry for synthesizing aromatic ketones, which are of interest in the synthesis of numerous fine chemicals such as drugs, fragrances, dyes and pesticides. 

The conventional method for preparation of these aromatic ketones involves reaction of the aromatic hydrocarbon with a carboxylic acid derivatives using a Lewis acid (AICI3, FeCl3, BF3, ZnCl2, TiCl4, etc.) ora Bronsted acid (polyphosphoric 

This chapter presents an alternative to classical Friedel-Crafts catalysis using heterogeneous catalysts such as zeolites, as we believe them to be the ultimate catalyst for the future production of aromatic ketones. After a short introduction to the literature, we focus on catalyst and process issues for different reactions. 

Sustainable Industrial Processes. Edited by F. Cavani, G. Centi, S. Perathoner, and F. Trifiro Copyright 2009 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-31552-9 

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An impressive number of papers and books has been published and numerous patents have been registered on the aq lation of aromatic compounds over solid catalysts. Recently Sartori and Maggi [1] have written an excellent review with 267 references on the use of solid catalysts in Friedel-Crafts acylation. In one section of this review, namely acylation of aromatic ethers or thioethers, the authors report work on acylation by solid catalysts such as zeolites, clays, metal oxides, acid-treated metal oxides, heteropolyacids or Nafion. When examining in details these results, it appeared very difficult for us to build upon these experimental results as the reaction conditions differ drastically from one paper to the next. This prompted us to reinvestigate the scope and limitations of the Friedel-Crafts acylation using heterogeneous solids as catalysts, trying as much as we could to rationalize the observed effects. 

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