Oxidation of dibenzothiophene with hydrogen peroxide in ionic liquids

Structurally different ionic liquids have been used as a medium for oxidation of dibenzothiophene with hydrogen peroxide in the presence of niobium pentachloride and oxaazacrown ethers. The maximum degree of oxidative conversion of dibenzothiophene (63%) was achieved in the presence of 5-(1,4,7,10-tet-raoxa-13-azacyclopentadecan-13-yl)pentadecanoic acid, an oxaazacrown ether bearing the carboxylic group in a side chain.