Aroylation of aromatics with aryl carboxylic acids over Nafion-H (polymeric perfluoroalkanesulfonic acid), an environmentally friendly solid acid catalyst

G K Surya Prakash,Mihirbaran Mandal,Thomas Mathew,Morteza Farnia,George A Olah,Mikael Begtrup

doi:10.3998/ark.5550190.0005.812

Abstract

Aromatic hydrocarbons undergo direct aroylation with arylcarboxylic acids over Nafion-H, an environmentally friendly, perfluorinated resinsulfonic acid catalyst to give benzophenones and their derivatives. Furthermore, one of the bistrifluoromethylated benzophenone derivative was trifluoromethylated to a new DDT analog.

Highlights

Extensive use of a wide variety of alkylating and acylating agents in Friedel- Crafts alkylation as well as acylation, respectively, has been studied.[1,2,3] Lewis acids of variable strengths were used.[3,4] Mechanistic aspects of different Lewis acid catalysed alkylation and acylation have been well studied.[5,6] Generally, Friedel-Crafts acylation requires molar amounts of the catalyst, which forms complexes with both the acylating agents and the product, carbonyl compounds.[7]
Aqueous workup has been generally used to decompose the carbonyl-Lewis acid complexes, which renders the catalyst in most cases non recoverable
Recent advances towards environmentally friendly processes which are economically feasible have shown that ionic liquid systems have great potential for various reactions.[9]

Summary

Introduction

Extensive use of a wide variety of alkylating and acylating agents in Friedel- Crafts alkylation as well as acylation, respectively, has been studied.[1,2,3] Lewis acids of variable strengths were used.[3,4] Mechanistic aspects of different Lewis acid catalysed alkylation and acylation have been well studied.[5,6] Generally, Friedel-Crafts acylation requires molar amounts of the catalyst, which forms complexes with both the acylating agents and the product, carbonyl compounds.[7]. Nafion-H, a perfluoroalkanesulfonic acid resin, has been found to be a suitable solid acid catalyst with high selectivity, and catalytic activity giving good yields of products.[14] The reaction with Nafion-H conveniently eliminates the use of volatile or noxious reagents. These unique properties have led to the application of Nafion-H to wide variety of organic reactions such as Friedel-Crafts type electrophilic reactions, synthesis of esters and ethers, various rearrangements etc.[14] we report our studies for the convenient intermolecular aroylation of aromatic hydrocarbons using benzoic acids as acylating agents in the presence of Nafion-H as a catalyst.

Results

Conclusion