Kinetics of the hydrogenation of 1-octene catalyzed by [Ni( o-MeO-dppp)(OAc) 2

Abstract

The kinetics of the nickel-catalyzed hydrogenation of 1-octene have been studied using nickel(II) acetate in combination with the ligand 1,3-bis(di( o-methoxyphenyl)phosphanyl)propane ( o-MeO-dppp). The effects of temperature and dihydrogen pressure, as well as the influence of the nickel and substrate concentrations have been studied ( T=30–60°C, p(H 2)=30–60 bar, [Ni]=0.35–2.81 mM, [1-octene]=0.98–3.91 M, ligand/Ni=1.1 in a mixture of dichloromethane and methanol). The kinetic study results in the surprisingly simple rate law r= k cat[Ni][1-octene] p(H 2). The kinetic data are consistent with a mechanism in which the terminating hydrogenolysis step of the nickel–alkyl complex is the rate-determining step of the catalytic cycle with all preceding steps at equilibrium. The first-order dependence on the substrate is confirmed by the results with other substrates, as the hydrogenation rate strongly depends on the nature of the substrate.