Preparation of manganese/Graphite oxide composite using permanganate and graphite: Application as catalyst in bromination of hydrocarbons

A highly efficient one-pot preparation of manganese/graphite oxide (MnO_X/GO) composite from graphite and KMnO4 is described. Hummers preparation method of GO requires a stoichiometric amount of KMnO4, as a result, the method produces a large amount of reduced Mn species. The Mn residue generally is a waste, therefore, we envisioned converting it to value-Added materials. A MnO_X/GO composite was prepared in one-pot by treating the unpurified GO with aqueous KOH. The composite was characterized by XRD, XAFS, SEM and TEM. Among various applications of the MnO_X/GO composite, we applied it as a recyclable catalyst for bromination of saturated hydrocarbons, one of the most basic but important chemical transformations. The MnO_X/GO composite is expected to be an efficient catalyst because of the high surface area and high accessibility of substrates derived from the 2- dimensional sheet structure. When the reaction of a saturated hydrocarbon and Br2 in the presence of catalytic MnO_X/GO was performed under fluorescent light irradiation, a brominated product was formed in high yield in a short reaction time. GO could strongly bind with Mn to prevent elution to the liquid phase, enabling the high recyclability.