Bulk andSolution Polymerization of Isobutene UsingTris(pentafluorophenyl)gallium and Tris(pentafluorophenyl)aluminum.

Fromthe standpoint of green chemistry, tris(pentafluorophenyl)gallium(7) and tris(pentafluorophenyl)aluminum (8) outperform all previously explored perfluoroarylated Lewis acids(PFLAs) for the polymerization of isobutene. In comparison to otherPFLA based systems, 7and 8do not requireultrahigh purity monomer, toxic chlorinated solvents, or expensiveand highly sensitive initiators (e.g., metallocenes). Moreover, comparedto other PFLA based initiator systems they provide much larger yieldsof high to medium molecular weight polyisobutene even at polymerizationtemperatures up to ambient. Stopping experiments indicate that strongBrønsted acids formed in situ by reaction with adventitious moisture(9and 10, respectively) induce cationicpolymerization protonically. Unlike other PFLA compounds which requireexpensive and/or energetically unstable precursors, 7and 8are readily synthesized from their correspondinggroup 13 halides in conjunction with bis(pentafluorophenyl)zinc (6), thereby lending themselves to commercial implementation. [ABSTRACT FROM AUTHOR]