Cationic degradation of poly (cyclohexene sulfide)

Summary The polymerization of cyclohexene sulfide initiated by triethyloxonium tetrafluoroborate is quantitative in a few minutes (at 0°C) but is followed by a complete degradation of the polymer to cyclic tetramer and an equimolar mixture of a 1,2,5-trithiepane derivative and cyclohexene. Also poly(cyclohexene sulfide), obtained by coordinative polymerization, degrades to the same compounds when it is treated with a trace of triethyloxonium tetrafluoroborate. The active species for the polymerization as well as for the degradation is believed to be the thiiranium ion. A revised mechanism for the trithiepane formation is proposed.