Determination of the Structure of Chlorobutyl and Bromobutyl Rubber by NMR Spectroscopy
1987 ◽
Vol 60
(4)
◽
pp. 636-646
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Keyword(s):
13C Nmr
◽
Abstract An analysis of the 1H and 13C NMR spectra of the chlorobutyl and bromobutyl rubbers was performed. Peaks were assigned based on evidence from broad-band decoupled, off-resonance decoupled, selectively decoupled and J-modulated spectra, the known characterization of butyl rubber and halogenation studies on model compounds. The assignment of the minor peaks indicated that the exomethylene-type structure is predominant in both halogenated rubbers. They also contain some nonhalogenated isoprenyl units. Bromobutyl rubber also contains some α-bromomethyl-type structures resulting from rearrangement of the exomethylene structure. The presence of endo-type structures will require further study for confirmation.