| Abstract: | The preparation of a high cis-1,4-polybutadiene, using a novel ternary catalyst system composed of triethylaluminum, a soluble nickel compound, and boron trifluoride diethyl etherate has been reported in the literature. The present paper reports the polymerization results obtained when the triethylaluminum was replaced with other alkylaluminums and the BF3 · Et2O was replaced with other BF3 complexes or HF · Et2O. When utilizing BF3 · Et2O, both the polymerization rate and the polymer DSV decreased significantly as the length of the alkyl group in the alkylaluminum increased from C1 to C6. However, the length and nature of the alkyl group had virtually no effect when utilizing BF3 · phenolate (BF3 · 2C6H5OH) and only a small effect with HF · Et2O; although the length of the alkyl group had no significant effect when using BF3 complexes of aromatic aldehydes, the branched alkyl groups gave greater polymerization rates than did the corresponding n-alkyls. In summary, the strongly acidic complexes, BF3 · phenolate and HF · etherate, promoted rapid polymerization when employed with any of the alkylaluminums. However, with other BF3 complexes, the alkylaluminum selected had an important influence upon either the conversion and/or the polymer DSV. |
