Immediate hydroxylation of arenes to phenols via V-containing all-silica ZSM-22 zeolite triggered non-radical mechanism

• Published in: Nature communications 2018-07, Vol.9 (1), p.2931-10, Article 2931
• Main Authors: Zhou, Yu, Ma, Zhipan, Tang, Junjie, Yan, Ning, Du, Yonghua, Xi, Shibo, Wang, Kai, Zhang, Wei, Wen, Haimeng, Wang, Jun
• Format: Article
• Language: English
• Subjects: 140/131; 140/133; 140/146; 140/58; 147/135; 147/143; 639/638/77/884; 639/638/77/885; 639/638/77/887; Alkylbenzenes; Aromatic compounds; Aromatic hydrocarbons; Benzene; Fine structure; Halogenated hydrocarbons; Humanities and Social Sciences; Hydrocarbons; Hydrogen bonds; Hydrogen peroxide; Hydroxylation; Ionic liquids; multidisciplinary; NMR; Nuclear magnetic resonance; Phenols; Science; Science (multidisciplinary); Silica; Silicalite; Silicon dioxide; Ultrastructure; Vanadium; Zeolites
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-05351-w

Hydroxylation of arenes via activation of aromatic C sp2 –H bond has attracted great attention for decades but remains a huge challenge. Herein, we achieve the ring hydroxylation of various arenes with stoichiometric hydrogen peroxide (H 2 O 2 ) into the corresponding phenols on a robust heterogeneous catalyst series of V–Si–ZSM-22 (TON type vanadium silicalite zeolites) that is straightforward synthesized from an unusual ionic liquid involved dry-gel-conversion route. For benzene hydroxylation, the phenol yield is 30.8% (selectivity >99%). Ring hydroxylation of mono-/di-alkylbenzenes and halogenated aromatic hydrocarbons cause the yields up to 26.2% and selectivities above 90%. The reaction is completed within 30 s, the fastest occasion so far, resulting in ultra-high turnover frequencies (TOFs). Systematic characterization including 51 V NMR and X-ray absorption fine structure (XAFS) analyses suggest that such high activity associates with the unique non-radical hydroxylation mechanism arising from the in situ created diperoxo V(IV) state. Hydroxylation of arenes via activation of aromatic C sp2 –H bond remains a challenge. Here, the authors have managed to get various arenes hydroxylated to corresponding phenols using stoichiometric hydrogen peroxide and a series of robust V–Si–ZSM-22 catalysts synthesized via an ionic liquid involved dry-gel-conversion route.