Anchoring of Fe(III)salicylamide onto MCM-41 for Catalytic Hydroxylation of Phenol in Aqueous Medium Using Hydrogen Peroxide as Oxidant

Abstract

Fe(III)salicylamide immobilized on MCM-41 has been developed for hydroxylation of phenol in water medium using hydrogen peroxide as the oxidant. In the first step, the amine group containing 3-aminopropyltrimethoxy silane has been immobilized on the surface of MCM-41 via co-condensation. The amine group upon condensed with methyl salicylate afford a bidentate ligand in the mesoporous matrix for anchoring Fe(III) ions in the second step. Small angle XRD, N2 adsorption–desorption isotherms, 13C and 29Si cross-polarization magic angle spinning NMR spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and diffuse reflectance UV–vis spectra were employed for the characterization of the catalysts. The heterogeneous iron salicylamide complex shows excellent catalytic activity in phenol hydroxylation using hydrogen peroxide as the oxidant and water as the solvent. Notably, phenol shows high conversion (64.6%) with very high selectivity for dihydroxybenzene compounds. The heterogeneous catalyst shows a successive slight decrease in catalytic activity when reused for three more times. Fe(III)salicylamide–MCM-41 has been synthesized successfully through an easy co-condensation route. XRD and N2 adsorption–desorption showed mesoporosity is retained even after complexation and FT-IR and diffuse reflectance UV–vis spectra confirmed the formation of complex. The heterogeneous catalyst exhibit excellent catalytic performance and stability in phenol hydroxylation reaction for the formation of dihydroxybenzene derivatives using H2O2.