Solvent-free oxidation of toluene in an ionic liquid with H2O2 as oxidant

Abstract

A series of 1-alkyl (or acetic acid)-3-methylimidazolium–metal chloride ionic liquids such as AmimBr Cl-,BF4-–MClx (A=ethyl, butyl, acetic acid and benzyl radicals; M=Fe, Cu, Sn, Mn, Ni, Co and Zn; x=2, 3 and 4) and Et3NHCl–FeCl3 were prepared by conventional method. These prepared ionic liquids were used as catalysts in selective oxidation of toluene with H2O2 as an oxidant. Their catalytic activities were compared in the absence of organic solvents. The ionic liquid bmimBr–FeCl3 showed higher catalytic activity with 10.2% conversion and 99% selectivity to benzaldehyde and benzyl alcohol. However, the catalyst was easily recovered and reused for three times without evident activity loss.