N-Methylpyrrole-Terminated Polyisobutylene Through End-Quenching of Quasiliving Carbocationic Polymerization
Document Type
Article
Publication Date
5-31-2005
Department
Polymers and High Performance Materials
Abstract
Quasiliving isobutylene polymerization initiated by 2-chloro-2,4,4-trimethylpentane/TiCl4/2,6-dimethylpyridine in 60/40 n-hexane/methyl chloride at -70&DEG; C was allowed to reach 98+% monomer conversion and then reacted with N-methylpyrrole. All polyisobutylene (PIB) chains alkylated the N-methylpyrrole ring to form a mixture of 46% 2-PIB-N-methylpyrrole and 54% 3-PIB-N-methylpyrrole. GPC indicated the absence of coupled PIB, confirming that exclusively monosubstitution had occurred. Complete H-1 and C-13 NMR chemical shift assignments were made for both isomers. The product was converted exclusively to mixed 2- and 3-PIB-N-methylpyrrolidine by catalytic hydrogenation using PtO2 in glacial acetic acid. Quantitative 1H NMR integration of PIB initiated from the difunctional aromatic initiator, 5-tert-butyl-1,3-di(2-chloro-2-propyl)benzene, showed exactly two N-methylpyrrole end groups per aromatic initiator residue. Quantitative reaction of PIB chains with N-methylpyrrole could not be obtained with BCl3 systems. In methyl chloride diluent at -45 &DEG; C, < 10% N-methylpyrrole capping was obtained after 70 min; in 1,2-dichloroethane at -10 &DEG; C, 77% of the PIB chains reacted with N-methylpyrrole after 15 min, and no further reaction was observed up to 18 h. In both BCl3 systems, GPC analysis showed the product to be unimodal, indicating the absence of coupling through dialkylation of N-methylpyrrole.
Publication Title
Macromolecules
Volume
38
Issue
11
First Page
4618
Last Page
4624
Recommended Citation
Storey, R. F.,
Stokes, C. D.,
Harrison, J. J.
(2005). N-Methylpyrrole-Terminated Polyisobutylene Through End-Quenching of Quasiliving Carbocationic Polymerization. Macromolecules, 38(11), 4618-4624.
Available at: https://aquila.usm.edu/fac_pubs/2753