Iron-catalyzed selective oxidation of sulfides to sulfoxides with the polyethylene glycol/O2 system

Readily available iron compounds were found to be active catalysts for the selective oxidation of sulfide to sulfoxide with molecular oxygen as the oxidant in polyethylene glycol (PEG). As an indispensable component, PEG had a great promotive effect on the reaction. Notably, high conversion (>99%) along with excellent chemo-selectivity of up to 94% could be attained by using Fe(acac)2 as the catalyst at 100 °C. This methodology was proved to be applicable for the transformation of various aromatic and aliphatic sulfides into the corresponding sulfoxides with high selectivity. PEG is considered to play a crucial role in stablizing the Fe(IV)-oxo species formed in situ which is supposed to be responsible for the sulfide oxidation.