Abstract: Copper Schiff base catalyst SB-Cu, cobalt Schiff base catalyst SB-Co and copper-cobalt bimetallic Schiff base catalyst SB-CuCo were synthesised by a two-step solvothermal method for the selective oxidation of p-methylphenol to p-hydroxybenzaldehyde, and the results of scanning electron microscopy-energy dispersive spectroscopy, Fourier transform infraredspectroscopy, and X-ray photoelectron spectroscopy showed that the SB-CuCocatalyst has good adsorption activation effect on molecular oxygen. After 96 h of continuous reaction at atmospheric pressure, temperature of 65 ℃, continuous oxygen bubbling, and n(p-toluene):n(sodium hydroxide):n(methanol) of 1:1.2:13, the conversion of p-toluene to methylphenol and the selectivity of p-hydroxybenzaldehyde under the action of the SB-CuCo catalyst reached 92.42%, and the selectivity of p-hydroxybenzaldehyde was 97.44%.The synergistic effect of copper and cobalt coordination sites resulted in a moderate activation intensity for molecular oxygen and a uniform and stable active site.The selective oxidation reaction mechanism of attacking the C—H bond at the benzyl position of p-methylphenol to generate benzyl radicals by superoxide complexes was further proposed by the study of the conformational relationship.

Key words: schiff base, p-cresol, selective oxidation, p-hydroxybenzaldehyde