Selectivity engineering of 4-phenoxyacetophenone by acylation of diphenyl ether with ion exchange resins: modeling of catalyst deactivation and remedies

Abstract

The synthesis of 4-phenoxyacetophenone, an important intermediate for the production of fine chemicals, was carried out via acylation of diphenyl ether with acetic anhydride using various solid acid catalysts, amongst which macroporous cation exchange resins were effective. The effects of various reaction parameters on the rate of reaction and selectivity were investigated to deduce the intrinsic kinetics of the reaction. However, the reusability studies demonstrated that the resin activity falls in subsequent reactions due to blocking of pores by larger products, particularly di-acylated derivatives rendering some pore networks ineffective. This could be modeled to extract both the rate constants and deactivation constants. A first-order model for independent deactivation was found to fit the data satisfactory. A strategy was then developed to increase the selectivity and reduce deactivation of catalyst.