Catalytic Activity of Manganese Oxide Anchored on to Alumina and Zirconia for the Synthesis of Dihydropyrimidinones: Role of Acidity, Crystal Phase and Morphology
Hagalahalli N. Hareesh,
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.
Keywords: Biginelli reaction, dihydropyrimidinones, manganese oxide on alumina/zirconia, role of acidity, solvent free synthesis.
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