Catalytic application of SO42-/Fe-ZrO2 nanoparticles synthesized by a urea hydrolysis method for environmentally benign one pot synthesis of 1,8-dioxodecahydroacridines

A series of Fe2O3-ZrO2 mixed oxides (FexZr) were prepared by a colloidal precipitation method using urea as a mild hydrolyzing agent. The sulfate ions were grafted onto the surface of the mixed oxide by treatment with dilute sulfuric acid and subsequent thermal activation. The resulting sulfate grafted mixed oxides (SFexZr) were characterized using XRD, FTIR, Raman, surface area measurement, UV-vis, XPS, TPD, SEM, FESEM and HRTEM techniques. XRD study indicated formation of a substitutional type solid solution in a limited composition range due to incorporation of iron ions into the zirconia lattice. The selective stabilization of the tetragonal phase of zirconia was observed in the mixed oxide system. The microstructural properties of the sulfate grafted mixed oxide were obtained from the Fourier analysis of the broadened XRD profiles. The presence of well dispersed iron oxide species in the zirconia lattice was ascertained from the Raman and UV-vis study. XPS and FTIR studies confirmed the presence of grafted sulfate functional groups. HRTEM analysis of the SFe10Zr sample revealed the presence of well dispersed mixed oxide particles with sizes in the range of 10-30 nm. The catalytic activity of the SFexZr material was evaluated for the synthesis of 1,8-dioxo-decahydroacridines by multicomponent condensation of dimedone, substituted aryl aldehydes and substituted anilines. A variety of dioxodecahydroacridine molecules were obtained with high yield and purity. The SFe10Zr material exhibited high surface area, and excellent catalytic activity for the synthesis of the 1,8-dioxo-decahydroacridine molecules.