Highly Efficient and Selective Oxidation of Benzyl Alcohol by WO42− Catalyst Immobilized by a Phosphonium-Containing Porous Aromatic Framework

Benzoic acid has found a wide range of applications in the chemical industry. The selective oxidation of benzyl alcohol is one of the main routes to produce benzoic acid. In this work, tris(4-bromobiphenyl)phosphine was chosen as a building block to synthesize PAF-181 with a high specific surface area and high yield via a Yamamoto–Ullmann reductive coupling reaction. Subsequently, the WO4@PAF-181 catalyst was successfully prepared via methylation and ion exchange, in which PAF-181 acts as a carrier while WO42− serves as the active catalytic site. The synergistic effect between functional carriers and active sites endows WO4@PAF-181 with distinctive catalytic property for efficient selective oxidation of benzyl alcohol to benzoic acid. Importantly, the catalyst can be conveniently recovered and reused by simple filtration, still maintaining its high catalytic activity.