Unsaturated telechelic oligoisobutylenes: Appraisal of the transfer efficiency of some dienes

Isobutylene was polymerized in the presence of 1,3‐pentadiene (BF 3 initiator) and 2,5‐dimethyl–2,4‐hexadiene (AlEt 2 Cl initiator) in CH 2 Cl 2 . Analysis combining examination of the H (mainly 300 MHz) and C NMR spectra and oxidative cleavage by RuO 4 of the copolymers obtained was carried out. Some homopolyisobutylenes (TiCl 4 initiator) were synthesized for comparison. The results show that it is possible to account for the structures of macromolecular chain ends by the assumption of hydride or methide transfer. The consequences of this assumption are thoroughly discussed.