Highly exo ‐olefinic polyisobutene synthesized using a recyclable acid

Scandium(III) and ytterbium(III) trifluoromethanesulfonate are active for the terminationless polymerization of moderate reactivity olefins (β-pinene, isobutene, styrene) in conjunction with a variety of initiators (e.g., Brønsted acids, halogens, and carbocation synthons). Neither Lewis acid requires chlorinated/toxic solvents to operate. The Yb congener is quantitatively recovered by aqueous extraction, reactivated by dehydration, and maintains its activity after multiple reuses. Both acids produce good yields (up to ~100%) of polyisobutene with an average exo-olefinic end-group content for Sc(OTf)3 of 86% (Alfa Asear) and 75% (Aldrich), and 94% for Yb(OTf)3 (Aldrich). The molecular weights of poly(β-pinene) and polyisobutene made by scandium(III) and ytterbium(III) trifluoromethanesulfonate, respectively, in combination with methanol are quite favorable at ambient temperature.