The Oligomerization of Butadiene with Nickel Complexes Produced by Means of the Electrolysis of Nickel(II) Chloride

The oligomerization of butadiene has been found during the electrolysis of solutions containing nickel(II) chloride and electron donors. The oligomerization was affected by the nature of the electron donors used. When the ethanolic solutions of tetrakis(pyridine)nickel(II) chloride or nickel(II) chloride and pyridine with tetra-n-butyl ammonium perchlorate or methanolic solutions without the perchlorate were electrolyzed in the presence of butadiene, a number of linear and dihydrogenated oligomers, with small amounts of branched oligomers, were obtained. The main oligomers were identified as n-octadiene, n-dodecatriene, and n-hexadecatetraene. By adding triphenylphosphine to the reaction system in place of pyridine, n-octatriene and alkoxyoctadiene were catalytically produced instead of hydrooligomers, accompanied by tetrakis(triphenylphosphine)nickel(0). A mechanism involving π-allyl intermediates was proposed for the oligomerization.