Polymerization of unsaturated episulfides

The polymerization of four unsaturated episulfides, vinylthiirane, endo‐2,3‐thioepoxy‐norbornene, cyclooctadiene‐1,5‐monoepisulfide and allyloxymethylthiirane can be affected by various ionic catalysts, BuLi, ZnEt2.H2O, BF3.Et2O, etc. In case of conjugated functional groups, some catalysts afford isomeric structures resulting from participation of both the olefinic and the episulfide group; the latter can also be opened separately, but even for radical initiation of vinylthiirane no 1,2‐structure of a pure vinyl polymer was obtained. A rearrangement of 1,3‐ to 1,5‐polymer has been observed in some cases by post treatment.