Reactions involving fluoride ion. Part 22. Dimerisation of perfluoro-2,3-dimethylbutadiene and related reactions

Abstract

Reaction of perfluoro-2,3-dimethylbutadiene (1) with caesium fluoride gives two dimers, the ratios being very temperature-dependent. The structures of the dimers and mechanism of formation are proposed. A corresponding reaction but in the presence of bromine provides a good route to perfluoro-2,3-dimethylbut-2-ene. Further fluorination of the dimers of (1) occurs over cobalt trifluoride and the product may be rationalised on the basis of an intermediate radical cation.