Carbonium ion rearrangement in the cationic polymerization of branched alpha olefins

The polymerization of olefins of the series (n‐1)methyl‐1‐alkenes through carbonium ion intermediates appears to involve a rearrangement from a secondary to a tertiary carbonium ion. The structure of the final polymer, as determined by nuclear magnetic resonance, depends on the relative rates of rearrangement and polymerization. In the homogeneous aluminum chloride catalyzed systems investigated, the rate of rearrangement decreases with increasing length of the monomer and is comparable to the rate of polymerization for 4‐methyl‐1‐pentene. The activation energy for rearrangement is lower than that for polymerization.