Zeolite catalytic heterogeneous acylations

Even though the catalytic systens described iu the preceding sections provide greater practicality than stoichiometric systens, their application in industrial synthesis is not widespread. However, in more recent times, maximum effort has been directed toward the use of solid acid catalysts. In fact, heterogeneous catalysts can be easily separated from the reaction mixture and reused they are generally not corrosive and do not produce problematic side products. Different classes of materials have been studied and utilized as heterogeneous catalysts for Friedel-Crafts acylations these include zeolites, (acid-treated) metal oxides, and heteropoly acids (HPAs) already utilized in the hydrocarbon reactions [24]. Moreover, the application of clays, perfluorinated resin-sulfonic acids, and supported (fluoro) sulfonic acids, mainly exploited in the production of fine chemicals, is the subject of intensive studies in this area. 

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