Studies on Nickel-Containing Ziegler-Type Catalysts. IV. Dimerization of Propylene to 2,3-Dimethylbutenes. Part-II

Article abstract of DOI:10.1246/bcsj.66.3079

A small amount of water was found to increase the activity of catalyst (A) for the selective dimerization of propylene to 2,3-dimethylbutenes (DMBS), Ni(naph)2/AlEt3/PR3/Diene/Chlorinated phenol, (A) where Ni(naph)2 denotes nickel naphthenate. The activity increased by about three to five times upon the addition of H2O in amounts of 0.2 to 0.8 mole per mole of AlEt3; the maximum activity was obtained at around 0.5 molar ratio of H2O to AlEt3. On the other hand, the reaction product between H2O and AlEt3 in a molar ratio of 0.5 was isolated and was identified to be μ-oxo-bis(diethylaluminum), the accelerating effect of which was also proved to be high. It is, therefore, concluded that the Lewis acidity of μ-oxo-bis(diethylaluminum) activates the Ni-H bond of the active species through coordination to the square-planar complex of nickel.