Silver nanoparticles supported on alumina–a highly efficient and selective nanocatalyst for imine reduction

Abstract

Silver nanoparticles supported on alumina were prepared and tested in the catalytic reduction of various imines to primary and secondary amines and were shown to be exceptionally active and chemoselective. Furthermore, the catalytic activity of the prepared nanocatalyst was also tested in the synthesis of secondary amines from primary amines in a tandem reaction protocol (oxidation-imination-reduction) using air and molecular hydrogen as oxidizing and reducing agents, respectively. The reported synthesis is performed under mild reaction conditions, which complies with the demands of modern organic synthesis. Due to the mild reaction conditions and high conversion as well as high selectivity, we consider that the utilization of silver nanoparticles supported on alumina represents an attractive and environmentally friendly alternative to the current synthesis of N-alkyl amines.

Selective Reduction of Azines to Benzyl Hydrazones with Sodium Borohydride Catalyzed by Mesoporous Silica‐Supported Silver Nanoparticles: A Catalytic Route towards Pyrazole Synthesis

“…As a continuation of our interest in the heterogeneous catalyzed reductive transformations by supported gold and silver nanoparticles, we introduce herein – for the first time – Ag/HMS‐NaBH 4 as an efficient and highly active catalytic system for the selective 1,2‐reduction of azines to the corresponding benzyl hydrazones, under mild conditions. Recently, silver nanoparticles supported on alumina were reported for the hydrogenation of imines to the corresponding amines, although high temperature and pressure were required (Scheme ) . In the combination of catalytic and synthetic points of view, the present selective heterogeneous reduction provides an alternative route towards the synthesis of benzyl hydrazones which offers advantages such as selectivity, recyclability, clean chemical synthesis, high isolated yields, use of more stable precursors avoiding harsh conditions and acidic additives.The catalytic results are interpreted on the basis of a kinetic analysis, as well as on the product characterization by LC‐MS and NMR spectroscopy.…”

Copper oxide as efficient catalyst for oxidative dehydrogenation of alcohols with air

“…23 Thus, silver nanoparticles or clusters supported on different metal oxides have been reported to be potential catalysts for the oxidative dehydrogenation of alcohols to carbonyl compounds. 10,24 Likewise, copper 25,26 and iron 27,28 have gained importance in recent years and iron oxidesalthough harmless, less toxic, and cheaperare not better catalysts than copper for oxidation reactions of alcohols at low temperatures. 29 Other homogeneous copper catalysts 30 and metallic copper catalysts with styrene as the hydrogen acceptor 31 are also reported for alcohol dehydrogenations.…”

Preparation and catalytic performance of ZrO2‐supported Pt single‐atom and cluster catalyst for hydrogenation of 2,4‐dinitrotoluene to 2,4‐toluenediamine

“…But, such processes entail detrimental environmental consequences, which have led to the banning of such practices. Fortunately, catalytic hydrogenation via supported metal catalysts has become the preferred choice due to its being an environmentally benign and highly efficient method . Precious metal nanoparticles have always been the active component for the 2,4‐DNT hydrogenation reaction .…”