Direct Synthesis of Phenol from Benzene by PdVO x Nanoparticles Using Molecular Oxygen

Light-Induced Efficient Hydroxylation of Benzene to Phenol by Quinolinium and Polyoxovanadate-Based Supramolecular Catalysts

Direct Hydroxylation of benzene to phenol with high yield and selectivity has been the goal of phenol industrial production. Photocatalysis can serve as a competitive method to realize the hydroxylation of benzene to phenol owing to its cost-effective and environmental friendliness, however it is still a forbidding challenge to obtain good yield, high selectivity and high atom availability meanwhile. Here we show a series of supramolecular catalysts based on alkoxohexavanadate anions and quinolinium ions for the photocatalytic hydroxylation of benzene to phenol under UV irradiation. We demonstrate that polyoxoalkoxovanadates can serve as efficient catalysts which can not only stabilize quinolinium radicals but also reuse H₂ O₂ produced by quinolinium ions under light irradiation to obtain excellent synergistic effect, including competitive good yield (50.1 %), high selectivity (>99 %) and high atom availability.

One-step hydroxylation of benzene to phenol over Schiff base complexes incorporated onto mesoporous organosilica in the presence of different axial ligands

Liquid-phase hydroxylation of benzene to phenol using Schiff base complexes anchored on a mesoporous organosilica support was investigated in various solvents when molecular oxygen was utilized as a green oxidant.

NH3 -Driven Benzene C-H Activation with O2 that Opens a New Way for Selective Phenol Synthesis

Catalytic benzene C-H activation toward selective phenol synthesis with O₂ remains a stimulating challenge to be tackled. Phenol is currently produced industrially by the three-steps cumene process in liquid phase, which is energy-intensive and not environmentally friendly. Hence, there is a strong demand for an alternative gas-phase single-path reaction process. This account documents the pivotal confined single metal ion site platform with a sufficiently large coordination sphere in β zeolite pores, which promotes the unprecedented catalysis for the selective benzene hydroxylation with O₂ under coexisting NH₃ by the new inter-ligand concerted mechanism. Among alkali and alkaline-earth metal ions and transition and precious metal ions, single Cs⁺ and Rb⁺ sites with ion diameters >0.300 nm in the β pores exhibited good performances for the direct phenol synthesis in a gas-phase single-path reaction process. The single Cs⁺ and Rb⁺ sites that possess neither significant Lewis acidic-basic property nor redox property, cannot activate benzene, O₂ , and NH₃ , respectively, whereas when they coadsorbed together, the reaction of the inter-coadsorbates on the single alkali-metal ion site proceeds concertedly (the inter-ligand concerted mechanism), bringing about the benzene C-H activation toward phenol synthesis. The NH₃ -driven benzene C-H activation with O₂ was compared to the switchover of the reaction pathways from the deep oxidation to selective oxidation of benzene by coexisting NH₃ on Pt₆ metallic cluster/β and Ni₄ O₄ oxide cluster/β. The NH₃ -driven selective oxidation mechanism observed with the Cs⁺ /β and Rb⁺ /β differs from the traditional redox catalysis (Mars-van Krevelen) mechanism, simple Langmuir-Hinshelwood mechanism, and acid-base catalysis mechanism involving clearly defined interaction modes. The present catalysis concept opens a new way for catalytic selective oxidation processes involving direct phenol synthesis.

Quinone-amine polymers as metal-free and reductant-free catalysts for hydroxylation of benzene to phenol with molecular oxygen

Quinone-amine polymers can be employed as a metal-free and reductant-free catalyst for the hydroxylation of benzene to phenol and can yield phenol as high as the transition metal catalyst.

High-performance recyclable V–N–C catalysts for the direct hydroxylation of benzene to phenol using molecular oxygen

High-performance recyclable V–N–C catalysts for the direct hydroxylation of benzene to phenol using molecular oxygen were prepared. N-dopants in the carbon material contributed to overcome the leaching of reactive species.