THERMAL-REACTIONS OF HEXAFLUOROBUTADIENE AND HEXAFLUOROCYCLOBUTENE WITH ELEMENTAL SULFUR

Hexafluorobuta-1,3-diene and hexafluorocyclobutene interact with eleme ntal sulphur under conditions of mutual conversion (greater than or eq ual to 280 degrees C) to give the same products, hexafluoro-3,6-dihydr o-1,2-dithiine (1), hexafluorothiolene-3 (2) and hexafluorothiolanethi one (3). The product composition and ratio depend on the reaction cond itions. Dithiine 1 and thiolene 2 were formed in competitive reactions . Their thermal stability and the retrocycloaddition reaction of dithi ine 1 have been studied. The latter reaction results in thiolene 2 in addition to the formation of hexafluorocyclobutene. This is consistent with a stepwise mechanism for the retrocycloaddition as well as the c ycloaddition reaction.