Immediate Hydroxylation of Benzene to Phenol over a Phase-Transition-Type Vanadium Catalyst via Multidimensional Regulation of Tungsten

The hydroxylation of inert benzene through the activation of the C_sp2–H bond is a representative reaction involving the transformation of C–H bonds to C–O bonds. Despite its far-reaching guiding significance, this process remains a complex scientific challenge. This issue was effectively addressed by achieving the hydroxylation of benzene with H₂O₂ into phenol utilizing a phase transition type catalyst of the VO_x-WO₃ series. This catalyst proved to be an efficient and economical synthesis route and presented a phenol yield of 90.2% (conversion >91%). This represents the highest conversion, which is attributed to the unique properties of the VO_x-WO₃ catalyst. In summary, the reaction path was optimized via the phase transformation of the catalyst at 70 °C. Herein, the introduction of tungsten regulates the acidity of the catalyst and the valence state of vanadium. Furthermore, it protects vanadium and forms a more active V–O–W active site, promoting the efficient transformation of the reaction.