Sulfonation of Tert-Alkyl Chlorides: Application to the Tert-Chloride-Terminated Polyisobutylene System

Document Type

Article

Publication Date

3-15-1991

Department

Polymers and High Performance Materials

Abstract

The direct sulfonation of tert-chloride-terminated polyisobutylene was carried out using acetyl sulfate in methylene chloride/hexanes diluent to produce low molecular weight model ionomer systems with narrow molecular weight distribution. The room temperature sulfonation of 2-chloro-2,4,4-trimethylpentane, which serves as a model for the polyisobutylene chain end obtained in the controlled cationic polymerization of isobutylene, was found to be quantitative after 3 h reaction. The two major products, isomeric beta,gamma-unsaturated sulfonic acids differing only in the location of the double bond, were the same products obtained from the sulfonation of 2,4,4-trimethyl-1-pentene, which serves as a model for the polyisobutylene chain end after quantitative dehydrochlorination. Near-monodisperse, tert-chloride-terminated, three-arm star polyisobutylene was synthesized under living cationic polymerization conditions using the tricumylchloride/TiCl4/pyridine initiation system in hexanes/methyl chloride cosolvents. Sulfonation was carried out directly upon the obtained polymer, and the sulfonated product was purified using ion-exchange chromatography. Structural elucidation was performed using NMR. Titration and molecular weight characterization revealed that sulfonation produced exactly one sulfonic acid group per polyisobutylene chain end.

Publication Title

Journal of Polymer Science Part A: Polymer Chemistry

Volume

29

Issue

3

First Page

317

Last Page

325

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