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

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 degreesC, 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. (C) 2001 Elsevier Science B.V. All rights reserved.