Hydrogenation and hydrogenolysis of nitro-, nitroso-, azo-, azoxy- and other nitrogen-containing compounds on palladium

The formation of nitroso-, azo- and azoxy-aromatics depends of a relatively complex scheme involving consecutive reactions. However, all different pro ducts can be produced in good yields with palladium catalysts, using optimi sed kinetics, selective poisoning or alloying. These reactions show differe nt dependencies of the reaction rate on Pd particle size and alloying. Solv ents have different roles, in addition to the usual one consisting in the s olubilisation of the reactants: they can change the solubility of hydrogen, compete with the reactants for adsorption at the metal surface or catalyse side reactions. (C) 2001 Elsevier Science B.V. All rights reserved.