Direct Dehydrogenative Amide Synthesis from Alcohols and Amines Catalyzed by γ-Alumina Supported Silver Cluster

The heterogeneously catalyzed reaction of alcohols with amines to form amides and H2 using the easily prepared and inexpensive heterogeneous catalyst, Ag/Al2O3 has been reported. Aromatic and aliphatic amides are functional groups of great importance in polymers, natural products, and pharmaceuticals. The catalyst precursors were prepared by impregnating oxides with an aqueous solution of silver nitrate followed by evaporation to dryness at 80°C and calcination at 600°C. The effect of acid-base characteristics of the support, the yield of product 3 and the initial rate were plotted as a function of the electronegativity of metal species in support material, which has been used as a parameter of acidity of metal oxides. The structure-activity relationship and reaction mechanism show that the reaction proceeds by a cooperation of co-ordinatively unsaturated silver site and acid-base sites of Al2O3 support.