The Introduction of Fluorinated Side-chains

Full details (see Vol. 1, p. 185) of the Japanese work on the preparation of trifluoromethylarenes from trifluoroiodomethane and iodoarenes in the presence of copper powder and a dipolar aprotic solvent have become available, and it appears that the best solvent in some cases is pyridine. This method (but with DMF as solvent) has also been used to prepare the compounds PhR [R = Me03C (CF3)3, CF3 0 (CF2)2, or perfluoro-2-tetra-hydrofurfuryl] in good yields from iodobenzene and the corresponding polyfluoroiodo-compounds. Perfluoroalkyl-copper compounds are very probably involved in such reactions, and the reactions of preformed n-perfluoroheptylcopper in dimethyl sulphoxide with the aromatic carbon-hydrogen bonds of benzene, toluene, p-xylene, nitrobenzene, and chlorobenzene also lead to (perfluoroalkyl)arenes (some replacement of chlorine occurs in the case of chlorobenzene). Homolytic substitution by perfluoro-heptyl radicals, perhaps within the co-ordination sphere of the copper atom, 

The gas-phase reaction of benzotrichloride with hydrogen fluoride over a chromium trifluoride catalyst is claimed to give a 93% yield of benzotri-fluoride, and pentafluorobenzaldehyde reacts with sulphur tetrafluoride to give a-jtf-heptafluorotoluene, C,Fj-CFjH (see also Vol. 1, p. 208), a better route to which apparently involves the fluorination of 2,3,4,5,6-pentafiuoro-benzal chloride. Bromination of the heptafluoro-compound gives perfluoro- 

A number of benzophenones (Ar COAr , where Ar = Ar = p-OaN-CeHa, At = Ar = CjFs, or Ar = CoFb, Ar = CeHg) have been converted into the corresponding difluorodiphenylmethanes (Ar CFjAr ) by treatment with sulphur tetrafluoride benzophenone-3,3, 4,4 -tetracarboxylic acid dianhydride yields the tetrakis(acyl fluoride) (10) under similar conditions. The action of sulphur tetrafluoride on mellitic acid, CtfCOaH), yields 

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