A remarkable synergic effect of water-soluble bimetallic catalyst in the hydrogenation of aromatic nitrocompounds

Hydrogenation of nitrobenzene can be catalyzed by the water-soluble catalys t PdCl2(TPPTS)(2) (TPPTS = tris(m-sulfonatophenyl)phosphine trisodium salt) under normal pressure at 65 degrees C in H2O/toluene biphasic solvent syst em. The exhibits higher catalytic activity and selectivity for the hydrogen ation of aromatic nitrocompounds, compared with PdCl2(TPPTS)(2) or H2PtCl6 alone. The transmission electron micrographs demonstrate that the monometal lic catalyst is composed of ultrafine palladium particles of almost uniform size while the particles of bimetallic catalyst are more widely distribute d in size than those of the monometallic ones. (C) 1999 Elsevier Science B. V. All rights reserved.