Chromium(vi) grafted mesoporous polyaniline as a reusable heterogeneous catalyst for oxidation reactions in aqueous medium

Abstract

A new Cr(VI)-grafted mesoporous polyaniline material (Cr-MPANI) has been prepared via simple and facile in situ radical polymerization of aniline followed by reaction with potassium dichromate. This material has been characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (DRS) and Thermogravimetric analysis (TGA). Powder XRD and TEM studies suggested the presence of mesophase and disordered wormhole-like mesopores in this sample. Cr-MPANI acts as a very efficient catalyst for the liquid phase oxidation of alkenes, alkanes and aromatic alcohols using 30% H₂O₂ as oxidant in water. Oxidation reactions were carried out under very mild conditions, and the desired products were obtained with very high selectivity and relatively high yields. Cr-MPANI can be recycled more than five times without an appreciable loss in activity for its respective catalytic reactions.