Mechanistic Insights into Visible Light-Induced Direct Hydroxylation of Benzene to Phenol with Air and Water over Pt-Modified WO3 Photocatalyst

Activation of C(sp2)-H in aromatic molecules such as benzene is one of the challenging reactions. The tungsten trioxide supported Pt nanoparticles (Pt-WO3) exhibited hydroxylation of benzene in the presence of air and H2O under visible-light (420 < λ < 540 nm) irradiation. The photocatalytic a...

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Bibliographic Details
Published in:Catalysts 2020-05, Vol.10 (5), p.557
Main Authors: Kurikawa, Yuya, Togo, Masahiro, Murata, Michihisa, Matsuda, Yasuaki, Sakata, Yoshihisa, Kobayashi, Hisayoshi, Higashimoto, Shinya
Format: Article
Language:English
Subjects:
Benzene
Catalysts
Chemical reactions
Density functional theory
Hydrocarbons
Hydrogen bonds
Hydrogen peroxide
Hydroxylation
hydroxylation of benzene
isotope H218O-labeling
Labeling
Light
Nanoparticles
Oxidation
phenol formation
Phenols
Photocatalysis
Pt-WO3 photocatalyst
Selectivity
Tungsten oxides
visible light
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Summary:Activation of C(sp2)-H in aromatic molecules such as benzene is one of the challenging reactions. The tungsten trioxide supported Pt nanoparticles (Pt-WO3) exhibited hydroxylation of benzene in the presence of air and H2O under visible-light (420 < λ < 540 nm) irradiation. The photocatalytic activities (yields and selectivity of phenol) were studied under several experimental conditions. Furthermore, investigations of mechanistic insight into hydroxylation of benzene have been carried out by analyses with apparent quantum yields (AQY), an H218O isotope-labeling experiment, kinetic isotope effects (KIE), electrochemical measurements and density functional theory (DFT) calculations. It was proposed that dissociation of the O–H bond in H2O is the rate-determining step. Furthermore, the substitution of the OH derived from H2O with H abstracted from benzene by photo-formed H2O2 indicated a mechanism involving a push-pull process for the hydroxylation of benzene into phenol.
ISSN:2073-4344
2073-4344
DOI:10.3390/catal10050557