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Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides (CHIPS)
Published on: June 20, 2014
Contact-electro-catalyzed direct hydroxylation of aromatic C-H bonds under ambient conditions
Jiawei Zhao1, Mengqian Xu2, Yanjie Wang1
1State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen, PR China.
Abstract:
The selective activation of inert aromatic C-H bonds for the synthesis of high-value phenols is of considerable scientific and industrial significance. Conventional free radical-based hydroxylation methods typically require ultraviolet irradiation or large amounts of sacrificial agents, which significantly limit their applicability. Here, we present a contact-electro-catalysis (CEC) approach that enables aromatic hydroxylation through hydroxyl radicals (·OH) and strong interfacial electric fields generated at the polytetrafluoroethylene (PTFE)-H2O interface via contact electrification. Using benzene as a model substrate, phenol was obtained via ·OH-mediated oxidation, and a variety of substrates with diverse electronic properties underwent efficient hydroxylation. For example, the transformation of 4-hydroxybenzoic acid yielded hydroquinone and 3,4-dihydroxybenzoic acid with maximum yields of 72.45 and 210.90 μmol·gcat-1 h-1, respectively. Electron paramagnetic resonance (EPR) confirmed the presence of ·OH, whereas nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry (LC-MS) analyses identified the products, thereby supporting mechanistic investigations. This work extends the application of contact-electro-catalysis to organic synthesis, providing a sustainable alternative despite existing challenges in selectivity and scalability.
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