Studies on the reduction of nitrobenzene to aniline catalysed by pd(acac)2-pyridine system

The complex, bis(acetylacetonato)palladium(II) in pyridine, is used as a homogeneous catalyst for the conversion of nitrobenzene to aniline. From a study of various operational parameters the optimum reduction was found to occur at 1 atm pressure and at room temperature in petroleum ether (b.p. 100–120°C) solvent, yielding 90% of aniline on input nitrobenzene basis. The complex [Pd¹¹(acac)H(C₆H₅NO₂)Py] was isolated under similar experimental conditions and was characterised by elemental analysis, magnetic, thermal and spectral studies. Formation of a phenylnitrene metal complex has been suggested as a hypothetical intermediate in the reduction process.