Dimerization of ethylene catalyzed by β-diketonate complexes of cobalt and nickel

Article abstract of DOI:10.1016/0304-5102(90)85037-I

The M(acac)_n-R_x Al₂Cl_6-x (M = Co, n = 2 or 3; Ni, n = 2; R = Et, i-Bu) system, both in the presence and absence of additives, is used for the dimerization of ethylene to a mixture of olefins consisting predominantly of 2-butenes. With the Co(acac)₃-Al(i-Bu)₃ system, a maximum conversion of 76% with selectivity to 2-butenes of 98 is achieved at 25°C and 8 kg cm^-2 ethylene pressure. Selectivity to 2-butenes is higher with the Co(III) complex compared to Co(II) in combination with trialkylaluminum. However, the three-component Co(acac)₂-Et₂AlCl-PR₃ system is superior to Co(acac)₃-Et₂AlCl-PR₃ for the dimerization of ethylene to 2-butenes. The effects of ethylene pressure and reaction temperature on the activity and selectivity to 2-butenes are also investigated.