Hydrogenation of nitrobenzene in the presence of platinum(II) and palladium(II) complexes containing alizarin: Radical intermediates

Abstract

The hydrogenat ion of nitroaromatics occurs with great o efficiency in the presence of only a small number of complex catalysts ~1-4) Earlier it was proposed (sl that the low activity of the 1 majori ty of metallocomplex catalysts in the latter reaction arose from the noncomplementary nature of the process: i.e. the intermediates metal-hydrides are two-electron donors, whereas nitroaromatics are one-electron acceptors. In previous reports ~ '4 '5 ) , metallocomplexes containing quinones or dyes as ligands were shown to be very effective catalysts in the hydrogenat ion of nitroaromatics, apparently 0.5 owing to their ability to transform the two-electron into a oneelectron process (6). In this work we have investigated the plat inum(II) and palladium(II) complexes containing alizarin as catalysts for conversion of n i t robenzene into aniline 141.