Cationic ring-opening polymerization behavior of six-membered cyclic s
ulfite (1) was examined. 1 was prepared by the reaction of 1,3-propane
diol with SOCl2 in 80% yield. Cationic ring-opening polymerization of
1 was carried out in the presence of cationic initiators such as benzy
l bromide (BnBr), BF3 . OEt(2), trifluoromethanesulfonic acid (TfOH),
and methyl trifluoromethanesulfonate (TfOMe) in bulk to afford a polym
er consisting of sulfite and ether moieties. The content of the poly(e
ther) unit was estimated to be 30-90%. The relative rate of polymeriza
tion by the initiators was estimated to be TfOH:TfOMe:BF3 . OEt(2) = 3
.5:2.5:1.0. Judging from the time-conversion curves and time-poly(ethe
r) production curves, the elimination of sulfur dioxide in the propaga
ting end of the polymer was confirmed to depend on the character of th
e counteranion.