Transition metal complexes of diazenes. Part XXXVII11For number XXXVI, see [1a].. Heterogeneous Rh(I) catalysis: synthesis of N-anilino-2,3-diphenylindole from azobenzene and diphenylacetylene Academic Article uri icon


  • Silica gel supported RhCl(PPh3)3 and silica gel attached {Rh(I)-O- [SiO2] + PPh3} are catalysts in the synthesis of N-anilino-2,3- diphenylindole from azobenzene and diphenylacetylene dissolved in toluene. The physisorption of RhCl(PPh3)3 on the silica gel surface can be described by the model of Freundlich affording an equilibrium constant K(ad) of 124 l/mol. Loading with 4 wt.% of RhCl(PPh3)3 affords SiO2[4.0] which is a better catalyst as compared to samples containing 0.8 and 8.7 wt.%. When the amount of SiO2[4.0] is increased at constant reaction volume, the reaction rate does not reach a constant value but passes through three maxima. The covalently bound catalyst {Rh(I)-O-[SiO2] + PPh3} is much less active and induces a maximum reaction rate when PPh3 is added in a twofold excess.

author list (cited authors)

  • Westernacher, S., Bl├╝mel, J., & Kisch, H.

citation count

  • 2

publication date

  • June 1996