Process for preparing butyl polymers with allylic halide functionality

A process for the preparation of a halogenated polymer analogous to halogenated butyl rubber comprising the steps of:

• (A) introducing into a suitable reaction vessel a monomer charge consisting essentially of from about 80 to about 95 weight percent of isobutylene and from about 5 to about 20 weight percent of a conjugated diolefin bearing an allylic halide moiety characterized in that said conjugated diolefin bearing an allylic halide moiety has the formula ##STR9## wherein R.sub.1 and R.sub.2 are selected from the group consisting of hydrogen and methyl groups and may be the same or different and R.sub.3 is hydrogen and X is selected from the group consisting of chlorine and bromine, based on a total of 100 weight percent of said isobutylene and conjugated diolefin bearing an allylic halide moiety, and an initiator having the formula ##STR10## wherein each R.sub.4 may be the same or different and is an alkyl, aryl or aralkyl group of 1 to 8 carbon atoms, Y is a carboxyl, alkoxyl, hydroxyl or halogen group and n is a positive whole number from 1 to 3, in an amount of from about 1.times.10.sup.-5 to about 1.times.10.sup.-3 moles per mole of said isobutylene at a temperature of from about -90.degree. C. to about -10.degree. C.,
• (B) adding a solution of from about 1.times.10.sup.-4 to about 5.times.10.sup.-2 moles of a Lewis acid per mole of isobutylene in an organic solvent to the reaction mixture of (A) at said temperature and polymerizing the monomers to form said halogenated polymer, and
• (C) recovering the halogenated polymer from the solution.