Highly selective oxidation of benzene to phenol with air at room temperature promoted by water

Xie, Jijia; Li, Xiyi; Guo, Jinsong; Luo, Lei; Delgado, Juan J.; Martsinovich, Natalia; Tang, Junwang

doi:10.1038/s41467-023-40160-w

Cited by 21 publications

(5 citation statements)

References 65 publications

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“…The conversion of benzene oxide to phenol has been documented in various catalytic systems. ,− Here, we describe a pathway in which nickel complex t 8 plays a catalytic role in the conversion of phenol from benzene oxide as well. Intermediate t 18 is reactive toward ring opening (breaking of the O–C bond) of its epoxide moiety via transition structure t TS 18 – 19 by overcoming an energy barrier of 14.5 kcal/mol.…”

Section: Resultsmentioning

confidence: 99%

DFT Mechanistic Investigation into Ni(II)-Catalyzed Hydroxylation of Benzene to Phenol by H₂O₂

Farshadfar,

Laasonen

2024

Inorg. Chem.

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Introduction of oxygen into aromatic C−H bonds is intriguing from both fundamental and practical perspectives. Although the 3d metal-catalyzed hydroxylation of arenes by H 2 O 2 has been developed by several prominent researchers, a definitive mechanism for these crucial transformations remains elusive. Herein, density functional theory calculations were used to shed light on the mechanism of the established hydroxylation reaction of benzene with H 2 O 2 , catalyzed by [Ni II (tepa)] 2+ (tepa = tris[2-(pyridin-2-yl)ethyl]amine). Dinickel(III) bis(μ-oxo) species have been proposed as the key intermediate responsible for the benzene hydroxylation reaction. Our findings indicate that while the dinickel dioxygen species can be generated as a stable structure, it cannot serve as an active catalyst in this transformation. The calculations allowed us to unveil an unprecedented mechanism composed of six main steps as follows: (i) deprotonation of coordinated H 2 O 2 , (ii) oxidative addition, (iii) water elimination, (iv) benzene addition, (v) ketone generation, and (vi) tautomerization and regeneration of the active catalyst. Addition of benzene to oxygen, which occurs via a radical mechanism, turns out to be the rate-determining step in the overall reaction. This study demonstrates the critical role of Ni-oxyl species in such transformations, highlighting how the unpaired spin density value on oxygen and positive charges on the Ni−O • complex affect the activation barrier for benzene addition.

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Section: Resultsmentioning

confidence: 99%

DFT Mechanistic Investigation into Ni(II)-Catalyzed Hydroxylation of Benzene to Phenol by H₂O₂

Farshadfar,

Laasonen

2024

Inorg. Chem.

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“…The yield of phenol increased first and then decreased as the H 2 O 2 /benzene ratio increased since phenol was overoxidated to diphenol and benzoquinone (Figure S6a). 26 Similarly, benzene conversion gradually increased while phenol selectivity decreased with increasing the temperature from 50 to 70 °C (Figure 7b). High temperature caused the overoxidation of phenol.…”

Section: Benzene Hydroxylation Reactionsmentioning

confidence: 87%

Vanadium-Modified TS-1 Catalysts with Enhanced Lewis Acid and Charge Density for Efficient Hydroxylation of Benzene to Phenol

Feng,

Fang,

Wang

et al. 2024

Ind. Eng. Chem. Res.

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Direct hydroxylation of benzene to phenol is an environmentally friendly strategy to produce phenol compared with the conventional process. In this work, vanadium-modified titanium silicate-1 (TS-1) with enhanced Lewis acid and charge density were prepared as catalysts for efficient hydroxylation of benzene to phenol in the presence of hydrogen peroxide as an oxidant under mild conditions. The hierarchical TS-1 zeolites with a high framework Ti content were synthesized in the presence of NH4HCO3, and then vanadium doping was used to change the acidity and charge density. It was found that NH4HCO3 favored the titanium substitution of framework sites and nanocrystal stacking of TS-1. Vanadium doping increased the amount of Lewis acid sites and the charge density associated with the framework Ti. The enhancement in acid and electron characteristics boosted the intrinsic catalytic reactivity of Ti-OOH species, which further improved the performances toward benzene hydroxylation. The presented strategy and mechanistic results clarified the relationship between the structure and acidity in TS-1 zeolite. It was also verified that hydroxyl radicals (•OH) rather than superoxide radicals (•O2 –) were the reactive agents responsible for the consecutive selective oxidation of benzene.

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“…Unlike the traditional heterogeneous catalytic system, where surface kinetics usually dominates the overall catalytic activity, an ideal photocatalytic system highly relies on efficient charge dynamics, which defines the amount of available surface electrons and holes. In photocatalytic C-H activation, both hydrophilic and oleophilic sites are essential to simultaneously realize the generation of polar oxidants and adsorption of organic reactants on the catalytic surface ( 11 ). Therefore, toward achieving efficient charge dynamics and surface kinetics for C-H activation, a photocatalyst not only needs to have excellent charge transport properties but also must have balanced hydrophilic and oleophilic reactive sites.…”

Section: Introductionmentioning

confidence: 99%

Atomically isolated Sb(CN) ₃ on sp ² -c-COFs with balanced hydrophilic and oleophilic sites for photocatalytic C-H activation

Teng,

Zhang,

Yang

et al. 2024

Sci. Adv.

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Activation of carbon-hydrogen (C-H) bonds is of utmost importance for the synthesis of vital molecules. Toward achieving efficient photocatalytic C-H activation, our investigation revealed that incorporating hydrophilic C≡N-Sb(CN) 3 sites into hydrophobic sp 2 carbon–conjugated covalent organic frameworks (sp 2 -c-COFs) had a dual effect: It simultaneously enhanced charge separation and improved generation of polar reactive oxygen species. Detailed spectroscopy measurements and simulations showed that C≡N-Sb(CN) 3 primarily functioned as water capture sites, which were not directly involved in photocatalysis. However, the potent interaction between water molecules and the Sb(CN) 3 -modified framework notably enhanced charge dynamics in hydrophobic sp 2 -c-COFs. The reactive species ·O 2 − and ·OH (ad) subsequently combined with benzyl radical, leading to the formation of benzaldehyde, benzyl alcohol, and lastly benzyl benzoate. Notably, the Sb(CN) 3 -modified sp 2 -c-COFs exhibited a 54-fold improvement in reaction rate as compared to pristine sp 2 -c-COFs, which achieved a remarkable 68% conversion rate for toluene and an 80% selectivity for benzyl benzoate.

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Highly selective oxidation of benzene to phenol with air at room temperature promoted by water

Cited by 21 publications

References 65 publications

DFT Mechanistic Investigation into Ni(II)-Catalyzed Hydroxylation of Benzene to Phenol by H₂O₂

DFT Mechanistic Investigation into Ni(II)-Catalyzed Hydroxylation of Benzene to Phenol by H₂O₂

Vanadium-Modified TS-1 Catalysts with Enhanced Lewis Acid and Charge Density for Efficient Hydroxylation of Benzene to Phenol

Atomically isolated Sb(CN) ₃ on sp ² -c-COFs with balanced hydrophilic and oleophilic sites for photocatalytic C-H activation

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Highly selective oxidation of benzene to phenol with air at room temperature promoted by water

Cited by 21 publications

References 65 publications

DFT Mechanistic Investigation into Ni(II)-Catalyzed Hydroxylation of Benzene to Phenol by H2O2

DFT Mechanistic Investigation into Ni(II)-Catalyzed Hydroxylation of Benzene to Phenol by H2O2

Vanadium-Modified TS-1 Catalysts with Enhanced Lewis Acid and Charge Density for Efficient Hydroxylation of Benzene to Phenol

Atomically isolated Sb(CN) 3 on sp 2 -c-COFs with balanced hydrophilic and oleophilic sites for photocatalytic C-H activation

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Product

Resources

About

DFT Mechanistic Investigation into Ni(II)-Catalyzed Hydroxylation of Benzene to Phenol by H₂O₂

DFT Mechanistic Investigation into Ni(II)-Catalyzed Hydroxylation of Benzene to Phenol by H₂O₂

Atomically isolated Sb(CN) ₃ on sp ² -c-COFs with balanced hydrophilic and oleophilic sites for photocatalytic C-H activation