Basic Al2O3 as a Recyclable Reagent for the Protection of Carbonyl Groups with Phenylhydrazine Derivatives and Semicarbazides.

Basic alumina is employed as an inorganic basic solid catalyst for the clean and less hazardous protection of carbonyl compounds, such as phenylhydrazones, 2,4-dinitrophenylhydrazones, semicarbazones, and thiosemicarbazones, under solvent-free conditions. The reactions proceed smoothly and require a short reaction time with good to excellent yields, and the alumina used can be recycled. [ABSTRACT FROM AUTHOR]