CATIONIC POLYMERIZATION BEHAVIOR OF 7-MEMBERED CYCLIC SULFITE

Cationic ring-opening polymerization behavior of a seven-membered cycl ic sulfite (1)was examined. 1 was prepared by the reaction of 1,4-buta nediol with SOCl2 in 58% yield. The cationic polymerization of 1 was c arried out at 0, 25, 60, or 100 degrees C with trifluoromethanesulfoni c acid (TfOH), methyl trifluoromethanesulfonate (TfOMe), BF3 . OEt2, S nCl4, methyl p-toluenesulfonate (TsOMe), or MeI as an initiator in bul k under a nitrogen atmosphere to afford the polymer with (M) over bar( n) 1000-10,400. The order of activities of the initiators for 1 was as follows, TfOH congruent to TfOMe > SnCl4 > BF3 . OEt2 > TsOMe congrue nt to MeI. The polymerization of 1 with TfOMe afforded a poly(sulfite) below 25 degrees C, but afforded a polymer containing an ether unit a t 60 degrees C, which was formed by a desulfoxylation. The higher the activity of the initiator was, the more easily the desulfoxylation occ urred. We expected volume expansion on polymerization because cyclic s ulfites have large dipole moment values, but it turned out that 1 show ed 4.34% shrinkage on polymerization. (C) 1997 John Wiley & Sons, Inc.