Hexafluorobutadiene is an organofluorine compound with the formula (CF2=CF)2. A colorless gas, it has attracted attention as an etchant in microelectronics. It is the perfluoroanalogue of butadiene.
Preparation
It can be prepared by coupling of fluorinated C2 precursors. Addition of iodine monochloride to chlorotrifluoroethylene gives iododichlorotrifluoroethane that can be coupled in the presence of mercury to give 1,2,3,4-tetrchlorohexafluorobutane:
- 2 CF2Cl−CFCl(I) + Hg → CF2Cl−CFCl−CFCl−CF2Cl + HgI2
Zn-induced dechlorination of this tetrachloride gives the desired perfluorinated diene:[1]
- CF2Cl−CFCl−CFCl−CF2Cl + 2 Zn → CF2=CF−CF=CF2 + 2 ZnCl2
Reactions
The diene can be rehalogenated, e.g. with bromine upon UV irradiation:[1]
- CF2=CF−CF=CF2 + 2 Br2 → CF2Br−CFBr−CFBr−CF2Br
Hexafluorobutadiene dimerizes via a [2+2] process at 150 °C to give perfluorinated divinylcyclobutanes.[2]
In the presence of the strong Lewis acid aluminium chlorofluoride, hexafluorobutadiene isomerizes to hexafluoro-2-butyne:[3]
- CF2=CFCF=CF2 → CF3C≡CCF3
See also
- Hexafluorocyclobutene, an isomer of C4F6
- Hexachlorobutadiene
References
- ^ a b Haszeldine, R. N. (1952). "849. Fluoro-olefins. Part I. The Synthesis of Hexafluorobuta-1:3-diene". Journal of the Chemical Society (Resumed): 4423. doi:10.1039/jr9520004423.
- ^ Lemal, David M.; Chen, Xudong (2005). "Fluorinated Cyclobutanes and Their Derivatives". In Zvi Rappoport; Joel F. Liebman (eds.). The Chemistry of Cyclobutanes. PATAI'S Chemistry of Functional Groups. pp. 955–1029. doi:10.1002/0470864028.ch21. ISBN 0470864001.
- ^ Petrov, V.A.; Krespan, C.G.; Smart, B.E. (1996). "Electrophilic reactions of fluorocarbons under the action of aluminum chlorofluoride, a potent Lewis acid". Journal of Fluorine Chemistry. 77 (2): 139–142. Bibcode:1996JFluC..77..139P. doi:10.1016/0022-1139(96)03391-x.