Further studies on the homogeneous hydrogenation of olefins using tris(triphenylphosphine)halogenorhodium(I) catalysts

Abstract

Studies on the homogeneous hydrogenation of olefinic hydrocarbons and other unsaturated substrates using tris(triphenylphosphine)halogenorhodium(I), RhX(PPh₃)₃(X = Cl or Br), as catalyst in benzene solution have been extended. The activation enthalpies and entropies for a number of olefins have been determined and, for other substrates, the relative rates of hydrogenation under standard conditions have been compared. The data can be broadly explained in terms of steric factors but electronic effects are clearly also important. Quantitative studies have been made of the kinetic isotope effect and the influence of the halide and of solvents.