Iron-chloride ionic liquid immobilized on SBA-15 for solvent-free oxidation of benzyl alcohol to benzaldehyde with H2O2

Abstract

Iron-chloride immobilized ionic liquid (SIL-FeCl3) was prepared by N-methylimidazole reacting with chloropropylsilane linked on the mesoporous silica SBA-15 and coordinating of FeCl3 to the imidazolium chloride grafted on the surface, as proved by XRD, TEM, NMR, FT-IR, ICP–MS, UV–vis and N2 adsorption–desorption technique. The results showed that the supported FeCl3 species were mainly distributed on the surface with the nonuniform distribution and the coordination linkage of imidazole ring to FeCl3 was stronger enough to keep its not leaching from the surface. The SIL-FeCl3 was demonstrated to be an efficient catalyst for a solvent-free oxidation of benzyl alcohol to benzaldehyde (BzH) using H2O2 as oxidant, exhibiting high TON (125.8mol/molFe). The novelty of the manuscript is based on the distribution of iron species on the surface detected by TEM and EDX and the higher catalytic activity of the catalyst for effective oxidation of alcohol under solvent-free condition The catalyst can be easily recovered and effectively reused without a significant loss in its activity and selectivity, which would lead to its potential application foreground for environmental friendly synthesis of chlorine-free BzH.