Chemoselective Hydrazine-mediated Transfer Hydrogenation of Nitroarenes by Co3 O4 Nanoparticles Immobilized on an Al/Si-mixed Oxide Support.

Cobalt oxide nanoparticles (size 2 to 3.5 nm) were successfully impregnated on an alumina-silica (mixed oxide) support through an experimentally viable and easily reproducible protocol. The prepared material was well characterized by XRD, HR-TEM, BET surface area, EDX and XPS analyses. Porous alumina-silica having a high surface area served as a protective heterogeneous support on which the well-dispersed Co3 O4 nanoparticles served as an active catalytic species for the hydrazine-mediated transfer hydrogenation of nitroarenes. About 2 mol % of the active catalyst in ethanol at 60 °C was adequate for a successful conversion. Moreover, transfer hydrogenation of nitroarenes by the catalyst was found to take place chemoselectively in the presence of other labile functional groups such as halide, alkene, nitrile, carbonyl, and ester. This inexpensive catalyst was also able to catalyze the reaction on a gram scale reaction and found to be robust and recyclable up to eight runs.