H3PW12O40/MCM-41 nanoparticles as efficient and reusable solid acid catalyst for the synthesis of quinoxalines

The condensation reaction of 1,2-diketones and o-phenylenediamines was investigated in the presence of nano-sized mesoporous silica (MCM-41) supported 12-tungstophosphoric acid (TPA) as solid acid catalyst. Nano-sized MCM-41 was synthesized and the catalysts with different loading amounts of TPA (5–15 wt.%) were prepared and characterized by XRD, FT-IR and SEM techniques. The results confirm good dispersion of TPA on the solid support. The catalyst is reusable many times without loss in its activity.