Hexafluoro-2-butyne explained

Hexafluoro-2-butyne (HFB) is a fluorocarbon with the chemical structure CF₃C≡CCF₃. HFB is a particularly electrophilic acetylene derivative, and hence a potent dienophile for Diels–Alder reactions.^{[1] [2]}

Synthesis and reactions

HFB is prepared by the action of sulfur tetrafluoride on acetylenedicarboxylic acid or by the reaction of potassium fluoride (KF) with hexachlorobutadiene.

It reacts with sulfur to give 3,4-bis(trifluoromethyl)-1,2-dithiete.

Cycloaddition of HFB and dithionitronium (NS₂⁺) gives the 1,2,5-dithiazolium cation. This derivative can be reduced to the 7 electron neutral radical. This particular 1,3,5-dithiazole is also rare example of a radical that can be obtained as solid, liquid, and gaseous states. As a gas, it is blue.^[3]

Notes and References

1. Book: 10.1002/047084289X.rn00669. Hexafluoro-2-butyne. Encyclopedia of Reagents for Organic Synthesis. 2006. Essers. Michael. Haufe. Günter. 0471936235.
2. Perfluoroalkyl(aryl)acetylenes. E S Turbanova, A A Petrov. Russian Chemical Reviews. 1991. 60. 5. 501–523. 10.1070/RC1991v060n05ABEH001092. 1991RuCRv..60..501T.
3. 10.1039/B001489N . The Isolation, Characterisation, Gas Phase Electron Diffraction and Crystal Structure of the Thermally Stable Radical CF₃CSNSCCF₃. 2000 . Brownridge . Scott . Du . Hongbin . Fairhurst . Shirley A. . Haddon . Robert C. . Oberhammer . Heinz . Parsons . Simon . Passmore . Jack . Schriver . Melbourne J. . Sutcliffe . Leslie H. . Westwood . Nicholas P. C. . Journal of the Chemical Society, Dalton Transactions . 19 . 3365–3382 .