Codimerization of butadiene and ethylene

Article abstract of DOI:10.1016/S0022-328X(00)89814-9

The catalytic system CoCl₂/1,2-bis(diphenylphosphino)ethane/Et₃Al, in 1,2-dichloroethane, shows high activity and selectivity for the production of cis-1,4-hexadiene from butadiene and ethylene. The temperature of reaction appears to be critical; between 80° and 110° cis-1,4-hexadiene is formed in high yield whereas below 80° more ethylene than butadiene is consumed, with the result that C₈ compounds are produced. Above 110° 1,4-hexadiene is isomerized to 2,4-hexadiene. Ayield of 8 × 10⁴ moles of 1,4-hexadiene per mole of CoCl₂ has been obtained at a rate of formation of the diene of 8 mol · l^-1 · h^-1. The catalytically active species is probably an octahedral complex of a cobalt(I) hydride with Et₃Al. A reaction scheme is proposed.