Hexafluorobutadiene is an organofluorine compound with the formula (CF<sub>2</sub>=CF)<sub>2</sub>. A colorless gas, it has attracted attention as an etchant in microelectronics. It is the perfluoroanalogue of butadiene.
It can be prepared by coupling of fluorinated C<sub>2</sub> 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:
Zn-induced dechlorination of this tetrachloride gives the desired perfluorinated diene:
The diene can be rehalogenated, e.g. with bromine upon UV irradiation:
Hexafluorobutadiene dimerizes via a [2+2] process at 150 ðC to give perfluorinated divinylcyclobutanes.
In the presence of the strong Lewis acid aluminium chlorofluoride, hexafluorobutadiene isomerizes to hexafluoro-2-butyne: