Catalytic Activity of Manganese Oxide Anchored on to Alumina and Zirconia for the Synthesis of Dihydropyrimidinones: Role of Acidity, Crystal Phase and Morphology

Manganese oxide supported on alumina and zirconia has been prepared by precipitation-impregnation method. The materials have been characterized by FT-IR, P-XRD, BET, TPD-NH3, TGA, SEM and TEM techniques for their textural properties. The catalytic activity of these materials has been explored in the synthesis of dihydropyrimidinones via.,Biginelli reaction. A rod like morphology is observed for zirconia containing 5% manganese oxide. These materials exhibited good catalytic activity in terms of isolated yield (>97%) and selectivity (100%) for the synthesis of dihydropyrimidinones. Acidity of the catalysts and the tetragonal phase of zirconia were found to play an important role in catalyzing this reaction. The catalyst with 5%Mn/ZrO2 exhibited distinctly different catalytic activity. The catalyst is reusable without losing its activity upto 5 cycles.