| 摘要 |
The invention comprises 1,3-dichlorotetra-fluorobenzene (a), 1,3-dibromotetrafluorobenzene (b) and 1-chloro-2,3,4,6-tetrafluorobenzene (c) and a method of preparing fluorinated aromatic compounds which includes the step of heating an aromatic compound, the nucleus of which is fully and exclusively halogen-substituted (at least one halogen being other than F), in a polar aprotic solvent with a dry fluoride of an alkali metal other than Li. Specified solvents are tetramethylene sulphone, dimethyl sulphone, dimethyl sulphoxide and dimethylformamide. Hexachlorobenzene (or partially fluorinated hexachlorobenzene) gives various chlorofluorobenzenes including (a) and chloropentafluorobenzene (d); hydrogenation (Pd) of (a) gives (c) and 1,2,3,5-tetrafluorobenzene which on bromination gives (b). Reaction of (d) with the following agents gives the products indicated in parentheses: copper bronze (decafluorodiphenyl), alkali metal methoxide (methoxychlorotetrafluorobenzenes), alkali metal hydrogen sulphide (chlorotetrafluorothiophenols), ammonium hydroxide (chlorotetrafluoroanilines), hydrazine hydrate (chlorotetrafluorophenylhydrazines) and H2-Pd (pentafluorobenzene). Ullmann reaction of (b) with bromopentafluorobenzene (e) gives m-perfluoroterphenyl; (e) is obtained together with its dibromotetrafluoro and tribromotrifluoro analogues from hexabromobenzene. Octafluoronaphthalene, obtained from octachloronaphthalene, may be re-submitted to the method of the invention to attain higher priority. |
