W-doped ZnO nanocomposite was easily prepared by sol-gel method. The sample was characterized using a variety of techniques including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, inductively coupled plasma and BET surface area measurement. This reagent can be used as an efficient and heterogeneous catalyst for the preparation of 1, 8-dioxo-octahydroxanthenes from aldehydes in ethanol under mild conditions. The structures of the products were characterized by their physical constants, comparison with authentic samples and IR, 1 H NMR and 13 C NMR spectroscopy. Easy preparation of the catalyst, mild reaction conditions, easy workup procedure, excellent yields and short reaction times are some advantages of this work. In addition, in this article and for the first time the preparation of 1, 8-dioxo-octahydroxanthenes from the protected derivatives of aldehydes including oximes, semicarbazones and 1,1-diacetates is reported.

In this study, 2,2 0 -bipyridine was treated with chlorosulfonic acid and 1,1 0 -disulfo-[2,2 0 -bipyridine]-1,1 0 -diium chloride, [BiPy](SO 3 H) 2 Cl 2 , as a new ionic liquid catalyst was obtained and characterized with a variety of techniques including IR, 1 H, and 13 C NMR, Hammett acidity function as well as mass spectra method. After preparation and characterization, this ionic liquid was used as an efficient catalyst for the green and mild synthesis of benzimidazole derivatives. In addition, this reagent is efficiently able to catalyze the preparation of benzimidazole derivatives from the protected derivatives of aldehydes including oximes and semicarbazones. All reactions are performed under mild conditions in excellent yields.