Reactions involving fluoride ion. Part XII. Reactions of polyfluoro-aromatic compounds with octafluorobut-2-ene

Octafluorobut-2-ene is much more difficult to dimerise, with fluoride ion, than is hexafluoropropene but perfluoro-3,4-dimethylhex-3-ene is obtained under more forcing conditions. In contrast, polyfluoroalkylations with octafluorobut-2-ene are very efficient and results with perfluoro-pyridine, -pyridazine, and -quinoline are described, giving various perfluoro-2-butyl derivatives. Reactions with nitropentafluorobenzene and perfluorotoluene are also described. The ¹⁹F n.m.r. spectra of perfluoro-2-butylaromatic compounds reveal restricted rotation, even at room temperature.