Zeolitic Imidazolate Framework‐8 in Piezo‐Assisted Mechanochemical Oxidation Reactions

Piezocatalysis, in combination with mechanochemical reactions, can create a respectable revolution in organic synthesis by enhancing product yield. In this study, ball milling merging with the synthesized zeolitic imidazolate framework‐8 (ZIF‐8), possessing a specific surface area of 1097 m 2 /g, was explored to catalyze the oxidative mechanochemical solventless homocoupling reaction of thiols (R‐SH) to disulfides (R‐S–S‐R) at 450 rpm within 120 min, as well as the oxidative mechanochemical solvent‐assisted reaction of toluene to phenol at 450 rpm within 180 min. 1‐butanethiol and 4‐aminothiophenol, as the models of thiol compounds, were oxidized to 1,2‐dibutyldisulfane and 4,4′‐disulfanediyldianiline, respectively, with the yields of 40% and 64%. The production of disulfides was monitored by 1 H‐NMR, 13 C‐NMR, and gas chromatography–mass spectrometry. Gas chromatography–flame ionization detection qualitatively and quantitatively explored the phenol production, as the phenol concentration was determined to be 5.550 mmol/L at a pH of 5 and 5.533 mmol/L under the condition of no adjusted pH (the initial pH of ≈3). In the toluene oxidation, O 2 •− species were detected as the main species, through radical trapping experiments. The ZIF‐8 particles could be reused after three cycles with no significant loss in the yield of thiol oxidation product, as further confirmed by their recorded Fourier transform infrared spectrum, powder X‐ray diffraction pattern, and field emission scanning electron microscopy images.