Determination de la structure de perfluoroalcenes a chaines longues par R.M.N. du 19F 2éme Partie : Perfluoroalcenes 2–3 et 4

The fluoride ion induced isomerisation of 1-perfluoroalkenes R_FCFCF₂ (R_F=C₄F₉, (I) -C₅F₁₁ (II), -C₆F₁₃ (III), -C₇F₁₅(IV) has been studied in the polar solvents DMF and VMSO. The reaction gives a mixture which changes to the thermodynamically stable isomer. ¹⁹F n.m.r. spectroscopy allows characterisation of products and shows that all alkenes formed are $\text{cis}$-derivatives. The products formed are explained on the basis of a cyclic intermediate involving participation of the metal cation.