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

Area of Science:

• Materials Science
• Organic Chemistry
• Catalysis

Background:

• Piezocatalysis offers a sustainable approach to organic synthesis by utilizing mechanical energy.
• Zeolitic imidazolate frameworks (ZIFs) exhibit unique properties suitable for catalytic applications.
• Mechanochemical reactions, driven by mechanical force, enable solvent-free or reduced-solvent synthesis.

Purpose of the Study:

• To investigate the catalytic potential of synthesized zeolitic imidazolate framework-8 (ZIF-8) in piezocatalytic reactions.
• To explore the application of ZIF-8 in oxidative mechanochemical reactions for organic synthesis.
• To evaluate the efficiency and reusability of ZIF-8 in thiol homocoupling and toluene oxidation.

Main Methods:

• Ball milling was employed for mechanochemical reactions, integrating synthesized ZIF-8 (surface area: 1097 m²/g).
• Oxidative homocoupling of thiols to disulfides and oxidation of toluene to phenol were performed.
• Product characterization utilized techniques including NMR, GC-MS, GC-FID, and radical trapping experiments.

Main Results:

• ZIF-8 effectively catalyzed the solventless homocoupling of 1-butanethiol (40% yield) and 4-aminothiophenol (64% yield).
• Toluene was oxidized to phenol (5.550 mmol/L) using ZIF-8 under solvent-assisted mechanochemical conditions.
• Superoxide radical anions (O₂•⁻) were identified as key species in toluene oxidation; ZIF-8 showed reusability over three cycles.

Conclusions:

• ZIF-8 is a promising piezocatalyst for efficient oxidative mechanochemical transformations in organic synthesis.
• The combined approach of piezocatalysis and mechanochemistry with ZIF-8 enhances product yield and offers a sustainable synthetic route.
• The reusability of ZIF-8 highlights its potential for cost-effective and environmentally friendly chemical processes.