Oxidation of cyclooctene to suberic acid using perrhenate-containing composite ionic liquids as green catalysts

A series of quaternary ammonium perrhenate/3-hexyl-1-methyl-imidazolium hydrogen sulfate ([Hmim]HSO4) composite ionic liquids has been prepared. For the first time, the composite ionic liquids are used both as catalyst and solvent in oxidation of cyclooctene to suberic acid in the presence of hydrogen peroxide as a green oxidant. It was found that organic perrhenate salts play the important role in improving the selectivity of cyclooctene oxidation to suberic acid. The yield of suberic acid under the mild conditions is from good to high.