Cationic polymerization of isobutylene in toluene: toward well-defined exo-olefin terminated medium molecular weight polyisobutylenes under mild conditions

Medium molecular weight polyisobutylenes (∼35 000 g mol⁻¹) with exo-olefin end groups (>80%) can be obtained by cationic polymerization of isobutylene in toluene using ⁱBu₂AlCl or ⁱBuAlCl₂·nOR₂ (n = 0.6–0.8) as co-initiators.