Hexafluoro- and perchlorofluoro-benzenes from perchlorofluoro-cyclohexanes and -cyclohexenes

Fluorine addition to polychlorinated and polybrominated ethenes and arenes using vanadium pentafluoride

“…We have found that trichloroethene reacted easily with vanadium pentafluoride at À10 to 10 8C without solvent to give 1,2,2-trichloro-1,2-difluoroethane (7). The formation of significant amounts of 1,1-difluorotrichloroethane or highly fluorinated products were not detected (Eq.…”

“…Because GC-MS analysis of 9 showed the presence at least four components with the close retention times, product 9 was assumed to be a mixture of isomers C 6 Cl 6 F 6 with cis-and trans-CFCl-CFCl and CF 2 -CCl 2 fragments. Noteworthy, that compounds C 6 Cl 6 F 6 were previously isolated from the reaction mixtures obtained by the fluorination of 3 with elemental fluorine [4][5][6], ClF 3 [7], or CoF 3 [8] or prepared by the chlorine addition to C 6 F 6 under UV irradiation [13]. In any cases, these products were characterised only by analytical data (C, Cl, F) and melting and/or boiling points [6,7,13].…”

“…Moreover, fluorine addition to halopentafluorobenzenes C 6 F 5 X (X: Cl, Br, I) proceeded without C-X bond cleavage and gave halo-undecafluorocyclohexanes C 6 F 11 X as final products [1]. In contrast, reactions of hexachlorobenzene with elemental fluorine [4][5][6], chlorine trifluoride [7], CoF 3 [8] or SbF 5 [9] always lead to a mixture of polychloropolyfluorocyclohexenes and/or polychloropolyfluorocyclohexanes which contained less than six chlorine atoms. Similarly, both parallel fluorine addition and F for Cl substitution occurred in reaction of polychloro-and polychlorofluoroalkenes with elemental fluorine, very often accompanied by oligomerisation of olefins [10].…”

Dehalogenative aromatization of perchlorofluoroalicyclic compounds C6Cl6F6, C10Cl8F8 and C5Cl4F5N in the vapour phase or in solution

“…The easier removal of chlorine than fluorine from perchlorofluorocyclohexanes over heated iron was demonstrated previously [8,9]. However, preparations of perchlorofluorocyclohexanes by fluorine addition to perchloroarenes using elemental fluorine [10][11][12], chlorine trifluoride [9] or cobalt trifluoride [8] are difficult to control, and usually these resulted in a mixture of cyclohexanes C 6 Cl n F 12Àn with an average number of chlorine atoms, n ¼ 4-7.…”

“…However, preparations of perchlorofluorocyclohexanes by fluorine addition to perchloroarenes using elemental fluorine [10][11][12], chlorine trifluoride [9] or cobalt trifluoride [8] are difficult to control, and usually these resulted in a mixture of cyclohexanes C 6 Cl n F 12Àn with an average number of chlorine atoms, n ¼ 4-7. To our knowledge, dehalogenation of perchlorofluorocyclohexanes C 6 Cl n F 12Àn with definite number of chlorine atoms, n ¼ 5, 6 and 7 was described only in reference [9]. In other cases, a mixture of cyclic chlorofluorocarbons C 6 Cl n F 12Àn with various n ¼ 5-7 was used for dehalogenation [8,[10][11][12].…”