Friedel–Crafts benzoylation of p-xylene over clay supported catalysts: novelty of cesium substituted dodecatungstophosphoric acid on K-10 clay Original Research Article

2,5-Dimethylbenzophenone is used extensively as a UV light stabilizer in plastics, cosmetics and films and produced by the benzoylation of p-xylene using homogeneous catalysts which pose several problems. The benzoylation of p-xylene with benzoyl chloride was carried out in a batch reactor using clay supported catalysts such as 20% (w/w) dodecatungstophosphoric (DTP) acid/K-10, 20% (w/w) Cs2.5H0.5PW12O40/K-10, 20% (w/w) ZnCl2/K-10 and K-10 itself and sulfated zirconia. Amongst these catalysts, 20% (w/w) Cs2.5H0.5PW12O40/K-10 was found to be a better catalyst which could be reused without any further chemical treatment eliminating the effluent disposal problem. This catalyst was fully characterized. The reaction obeys the Eley–Rideal type of mechanism with a weak adsorption of the benzoylating species.