Silica†supported polymer†palladium complexes as catalysts for the reduction of nitro and azo groups

Palladium complexes of cross‐linked polyvinylpyridine and poly(acryl‐amide‐methacrylic acid) copolymer coated on silica gel have been used as catalysts for the hydrogenation of azo and nitro groups under 101 kPa hydrogen pressure at 30°C. Nitro aromatics were selectively and almost completely reduced to the corresponding amines. A rate equation of the type, rate = k[cat][H2] has been derived for the hydrogenation of nitrobenzene on the basis of the experimental results and kinetic data. Also the selective hydrogenation of azobenzene to hydrazobenzene could be achieved with these catalysts. Copyright © 1992 Society of Chemical Industry