Hexafluoro-2-butyne
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.[2][3]
Synthesis and reactions[edit]
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.[4]