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 Hβ zeolite-supported tungstophosphoric acid catalyst (HPW/Hβ). 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/Hβ, due to the synergistic effect between HPW and Hβ zeolite. Inductively coupled plasma results indicated the dealumination of the Hβ zeolite due to the treatment of tungstophosphoric acid (HPW), offering more active centers in HPW/Hβ. X-ray diffraction and Brunauer–Emmett–Teller results demonstrated that HPW was highly dispersed on the surface and in the larger pores of the Hβ zeolite. NH3 temperature-programmed desorption results showed HPW/Hβ has larger amounts of strongly acidic sites than the Hβ 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.