Friedel-Crafts acylation of anisole with hexanoic acid catalyzed by Hβ zeolite-supported tungstophosphoric acid

Friedel-Crafts acylation of anisole with hexanoic acid was studied and an efficient method was established for the green synthesis of 4-methoxy phenyl hexyl ketone over an H beta zeolite-supported tungstophosphoric acid catalyst (HPW/H beta). The conversion of hexanoic acid was 100 % and the yield of 4-methoxy phenyl hexyl ketone reached 89.2 % under the optimized reaction conditions over HPW/H beta, due to the synergistic effect between HPW and H beta zeolite. Inductively coupled plasma results indicated the dealumination of the H beta zeolite due to the treatment of tungstophosphoric acid (HPW), offering more active centers in HPW/H beta. X-ray diffraction and Brunauer-Emmett-Teller results demonstrated that HPW was highly dispersed on the surface and in the larger pores of the H beta zeolite. NH3 temperature-programmed desorption results showed HPW/H beta has larger amounts of strongly acidic sites than the H beta zeolite, accounting for its good catalytic performance. Furthermore, this catalyst can be recycled for four times with the yield of 4-methoxy phenyl hexyl ketone maintained at roughly 70 %, demonstrating its relatively good stability.