The combination of relatively low-cost ionic liquids, simple copper salt, and terminal oxidant tert-butyl hydroperoxide provided an efficient and environmentally friendly approach to the preparation of ionone-like dienones. Six pyridinium ionic liquids were evaluated in allylic oxidation of α-ionone and β-ionone. The 60%-70% yields of 3-oxo-α-ionone were obtained with 0.02 0.20 mmol of CuCl2·2H2O as catalyst, 3-5 mmol of tert-butyl hydroperoxide as oxidant and 1 g of [Bpy]PF6 as solvent for 4-20 h at 60℃. The facile recovery and recycle of catalyst were also achieved. More significantly, peculiar phase behaviors of [Bpy]PF6 and [Epy]PF6 offered the catalytic system advantages of homogeneous reaction and heterogeneous separation. Scanning electron microscope （SEM） images of [Bpy]PF6 provided evidences for the behaviors. Transmission electron microscope （TEM） micrographs showed copper salt nanoparticles catalyst formed and stabilized in pyridinium ionic liquids.
