144. Direct preparation and some reactions of chlorofluorobenzenes

Abstract

Direct fluorination of hexachlorobenzene gives chlorofluorocyclohexanes of average composition [C,Cl,F,] . Dehalogenation of this mixture with iron filings packed in a cobalt fluoride reactor gives high yields of hexafluorobenzene and chlorofluorobenzenes. Chloropentafluorobenzene forms a Grignard reagent with magnesium in diethyl ether when activated with 1,2-dibromoethane but forms material of high molecular weight when tetrahydrofuran is used as solvent.

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

“…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].…”

Ullmann Reaction Optimization within Bitolyl and Decafluorobiphenyl Synthesis

“…Decafluorodiphenyl is produced using Ullmann reaction with chloropentafluorobenzene [25][26] over copper, while slightly raising temperature from 230 to 320-360 °C increases reaction output a little (from 69 % to 73 %). Using bromopentafluorobenzene under the same conditions substantially increase product output [27][28][29] (from 87% to 91%), yet replacing copper with activated nickel 30 , produced by reducing nickel bromide or nickel iodide with lithium naphthalede, is unsuccessful (37-49%).…”

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

“…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].…”

“…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]. The related syntheses of polyfluorinated naphthalenes and pyridines from the corresponding perchlorofluorocycloalkanes and perchlorofluorocycloalkenes were not reported except of the defluorination of perfluorinated materials [1].…”