Investigation of a sulfonic acid functionalized ammonium-based permanganate hybrid as a sustainable oxidative catalyst for selective conversion of organic sulfides to sulfoxides

Abstract

In this report, two organic–inorganic hybrids of permanganate anions, namely N,N′-diethyldisulfoammonium permanganate [DEDSA][MnO₄] and 1,4-disulfopiperazinium permanganate [DSPZ][MnO₄]₂, were developed as thermally stable oxidants through ion exchange reactions of the respective organic chlorides with a KMnO₄ salt. Various spectroscopic and analytical techniques like FT-IR, PXRD, Raman, UV-vis DRS, SEM and EDX were employed to confirm the structural compositions of both the hybrids. Comparative thermogravimetric analyses with reference to the parent organic chloride salts expressed substantial changes in their thermal stabilities as well as their hydrophilic/hydrophobic properties. The oxidative ability of [DEDSA][MnO₄] was observed through its use as an efficient recyclable homogeneous catalyst for selective formation of sulfoxides from aryl/alkyl aryl sulfides in 10% aqueous sulfuric solution at 80 °C for 40–120 min of reaction, resulting in 67–98% yields of products.