Photocatalytic Oxidation of Sulfides to Sulfoxides via a Mesoporous WO3 Catalyst

The selective oxidation of sulfides to sulfoxides has both biological and industrial importance, as well as use in the practical application of decontaminating mustard gas. Photocatalytic processes have been commonly used for this purpose, especially in scenarios where it can offer more environmentally benign procedures than traditional procedures. The metal oxide nanoparticle catalyst WO3 has not been widely studied for the oxidation of sulfides in various applications, despite having been shown to be effective in other oxidative processes, such as those intended to degrade contaminants. Within this study, mesoporous WO3 nanoparticles were synthesized from a silica template, and their ability to oxidize various sulfide compounds was investigated. This system uses visible light (rather than UV rays) to promote the reaction, an aldehyde as the primary oxidant, and a solvent (HFE-7100) which promoted high levels of oxygen available for reaction, as well as having the potential benefit of being more benign than other oxidants such as H2O2. The investigation of substrate scope (e.g. aromatic and electronic effects) on reaction rates indicated the ability of this system to oxidize sulfides that are less readily oxidized by many systems.