Sulfated SO4 2−/WO3 as an efficient and eco-friendly catalyst for solvent-free liquid phase nitration of toluene with NO2

With the increase in environmental awareness, developing a highly efficient and environmentally benign nitration process has very important academic and applied industrial values in the synthesis of nitro-compounds. Towards this goal, we have developed an efficient and environmentally friendly approach for solvent-free liquid phase nitration of toluene by employing NO 2 as a nitrating agent and sulfated SO 4 2− /WO 3 as a catalyst replacing traditional nitric acid–sulfuric acid under mild conditions. The results indicate that SO 4 2− /WO 3 as an effective and eco-friendly catalyst exhibits excellent catalytic activity and reusability for the nitration of toluene with NO 2 . In addition, the possible pathway for liquid phase nitration of toluene with NO 2 over sulfated SO 4 2− /WO 3 catalyst was suggested. The present method makes this nitration process safe and environmentally friendly, and has the potential to enable a sustainable production of nitro-compounds from the liquid phase nitration of aromatic hydrocarbon with NO 2 in industrial applications.