A series of copper catalysts based on oxalyl diamide polymers were prepared and screened for the coupling of m-bromobenzaldehyde with phenol. The reaction results demonstrated that the copper catalyst Cu@PSAO of 2,2-diamino- diphenyl sulfide oxalyl diamide polymer exhibited excellent selectivity for the C—O coupling of m-bromobenzaldehyde with phenol with very high selectivity and high activity. The yield of m-phenoxybenzaldehyde can reach 99%. A series of characterizations including X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), infrared absorption spectroscopy (FTIR), and specific surface area test (BET) were employed to study the relationship between the structures and chemical properties of the catalyst Cu@PSAO. Through the characterization results, it was observed that Cu@PSAO presented an irregular three-dimensional structure, and the three-dimensional structure was formed by cross linked or rolled through the coordination of copper with the oxalyl diamide polymers. Compared with the existing processes, the Cu catalyst Cu@PSAO can significantly enhance the selectivity of the C—O coupling of m-bromobenzaldehyde with phenol and effectively avoid the disproportionation side reaction of bromobenzaldehyde under the alkaline condition. The catalyst Cu@PSAO was prepared easily and could be separated simply from the reaction mixture after the reaction. It still maintains stable catalytic performance after multiple reaction cycles, thus exhibiting application prospects for industrial processes.

Key words: m-phenoxybenzaldehyde, copper catalyst, C—O coupling reaction, oxalediamine polymer