Selective Sulfide Oxidation with Hydrogen Peroxide Catalyzed by a Silica-Supported Polypyridyl-Iron Complex

Area of Science:

• Catalysis
• Materials Science
• Green Chemistry

Background:

• Non-heme iron oxygenases inspire biomimetic catalysts.
• Sulfide oxidation is crucial in chemical synthesis.
• Developing robust and recyclable oxidation catalysts is essential.

Purpose of the Study:

• To immobilize an iron(II)-polypyridyl complex (Fe-TPAN) onto silica beads.
• To investigate the catalytic activity and selectivity of the immobilized catalyst for sulfide oxidation.
• To compare the performance of the heterogeneous catalyst with its homogeneous counterpart.

Main Methods:

• Covalent anchoring of [Fe-TPAN] onto silica beads.
• Characterization using FT-IR, TGA, XPS, and TEM.
• Testing catalytic oxidation of sulfides using hydrogen peroxide.

Main Results:

• The silica-supported catalyst [Fe-TPAN@SiO2] was successfully prepared and characterized.
• The catalyst exhibited high selectivity for mono-oxygenation of sulfides to sulfoxides.
• The immobilized catalyst showed enhanced conversion and recyclability (up to six cycles) compared to the homogeneous complex.

Conclusions:

• The [Fe-TPAN@SiO2] catalyst offers an efficient and reusable system for sulfide oxidation.
• A mechanism involving iron-oxygen intermediates and Fenton-type processes is proposed.
• This work provides a promising heterogeneous catalyst for selective oxidation reactions.