The sulfuration and reversion products of brominated poly(isobutylene-co-isoprene) (BIIR) were characterized through the use of a model compound, brominated. 2,2,4,8,8-pentamethyl-4-nonene (BPMN). The reaction of BPMN with S, produced bisallylic polysulfides of various ranks, yielding sulfur bromide intermediates that likely contributed to the rapid oxidation of allylic sulfides into thiophenes. Reductive cure reversion to pentamethylnonene was also observed in the latter stages of vulcanization. The reaction of 2,2'-dithiobisbenzothiazole with BIIR and BPMN produced a stable adduct that reduced the concentration of allylic bromide available for vulcanization. (C) 2003 Wiley Periodicals, Inc.