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

Abstract

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 NO2 as a nitrating agent and sulfated SO4 2−/WO3 as a catalyst replacing traditional nitric acid–sulfuric acid under mild conditions. The results indicate that SO4 2−/WO3 as an effective and eco-friendly catalyst exhibits excellent catalytic activity and reusability for the nitration of toluene with NO2. In addition, the possible pathway for liquid phase nitration of toluene with NO2 over sulfated SO4 2−/WO3 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 NO2 in industrial applications.