Designing of Permanganate Based Functionalized Organic-Inorganic Hybrid as Environmentally Benign Oxidative Catalyst for Controlled Oxidation of Benzyl Alcohol

In this study, an organic-inorganic hybrid [MDSIM][MnO₄] of 2-methyl-1,3-disulfoimidazolium [MDSIM]⁺ cation with permanganate (MnO₄⁻) anion was prepared as solid material via metathesis reaction of 2-methyl-1,3-disulfoimidazolium chloride ([MDSIM]Cl) ionic liquid with potassium permanganate. Structural composition of this hybrid was established by FT-IR, UV-Vis DRS, Powder-XRD, Raman, Scanning Electron Microscopy, Energy Dispersive X-ray analysis and elemental mapping studies.Thermo-gravimetric analysis pointed out its extensive thermal stability, whereas SEM images indicated heterogeneous morphology of various sized crystalline granules. The material was explored as recyclable homogeneous oxidative catalyst for controlled oxidation of primary/secondary benzyl alcohols to carbonyl compounds in 10% aqueous H₂SO₄ and acetonitrile solution at 80 °C and in solvent-aided grinding method at room temperature. The role of acid was identified as a co-catalyst in the oxidation reactions. Theoretical calculations using density functional theory (DFT), regarding the optimized structure of the hybrid and proposed mechanism of oxidation reaction, also provided support towards the efficacy of this recyclable material as a catalyst as well as oxidant.

Graphical Abstract

An organic-inorganic hybrid of 2-methyl-1,3-disulfoimidazolium cation with MnO₄⁻ anion was developed as recyclable oxidative catalyst for selective conversion of benzyl alcohol to aldehydes in acidic conditions. Density functional theory was used to optimize the structure of hybrid and plausible mechanism of the oxidation reaction.