Patent ID: 7244870

Claim:
A process for the preparation of polyisobutenes in which at least 80 mol % of the polymer chains have at least one olefinically unsaturated terminal group, by cationic polymerization of isobutene or isobutene-containing monomer mixtures in the condensed phase, wherein the polymerization is carried out in the presence of an initiator system comprising i) a Lewis acid selected from titanium(IV)chloride and boron-trichloride and ii) at least one organic compound I having at least one functional group of the formula FG where X is selected from halogen, C 1 -C 6 -alkoxy and C 1 -C 6 -acyloxy, R 1 is hydrogen or methyl and R 2 is methyl or forms a C 5 - or C 6 -cycloalkyl ring together with R 1 or with the moiety to which the functional group FG is bonded, and R 2 may also be hydrogen if the functional group FG is bonded to an aromatic or olefinically unsaturated carbon atom, which forms a carbocation or a cationic complex under, the polymerization conditions, the organic compound I being selected from compounds of the formulae I-A to I-D: where X has the abovementioned meanings, n is 1, 2, 3, 4 or 5, R 3 , R 4 and R 10 , independently of one another, are each hydrogen or methyl, R 5 , R 6 and R 7 , independently of one another, are each hydrogen, C 1 -C 4 -alkyl or a group CR 3 R 4 —X, where R 3 , R 4 and X have the abovementioned meanings, and R 8 is hydrogen, methyl or a group X and R 9 and R 9′ are each hydrogen or a group X, in a solvent inert toward the Lewis acid, the Lewis acid being used in less than the stoichiometric amount, based on the functional groups FG of the compound I.