REACTIONS OF TETRAFLUOROETHYLENE OLIGOMERS. PART 1. SOME PYROLYTIC REACTIONS OF THE PENTAMER AND HEXAMER AND OF THE FLUORINE ADDUCTS OF THE TETRAMER AND PENTAMER

Article abstract of DOI:10.1016/S0022-1139(00)82660-3

Pyrolyses of these highly branched fluorocarbons over glass beads caused the preferential thermolyses of C-C bonds where there is maximum carbon substitution.Fluorinations of perfluoro-3,4-dimethylhex-3-ene (tetramer) (I) and perfluoro-4-ethyl-3,4-dimethylhex-2-ene (pentamer) (II) over cobalt (III) fluoride at 230 deg C and 145 deg C respectively afforded the corresponding saturated fluorocarbons (III) and (IV), though II gave principally the saturated tetramer (III) at 250 deg C.Pyrolysis of III alone at 500-520 deg C gave perfluoro-2-methylbutane (V), whilst pyrolysis of III in the presence of bromine or toluene afforded 2-bromononafluoorobutane (VI) and 2H-nonafluorobutane (VII) respectively.Pyrolysis of perfluoro-3-ethyl-3,4-dimethylhexane (IV) alone gave a mixture of perfluoro-2-methylbutane (V), perfluoro-2-methylbut-1-ene (VIII), perfluoro-3-methylpentane (IX), perfluoro-3,3-dimethylpentane (X), and perfluoro-3,4-dimethylhexane (III).Pyrolysis of IV in the presence of bromine gave (VI) and 3-bromo-3-trifluoromethyldecafluoropentane (XI): with toluene, pyrolysis gave VII and 3H-3-trifluoromethyldecafluoropentane (XII).Pyrolysis of II at 500 deg C over glass gave perfluoro-1,2,3-trimethylcyclobutane (XIII) and perfluoro-2,3-dimethylpenta-1,3(E)- and (Z)-diene (XIV) and (XV) respectively.The diene mixture (XIV and XV) was fluorinated with CoF3 to give perfluoro-2,3-dimethylpentane (XVI) and was cyclised thermally to give the cyclobutene (XIII).Pyrolysis of perfluoro-2-(1'-ethyl-1'-methylpropyl)-3-methylpent-1-ene (XVII) (TFE hexamer major isomer) at 500 deg C gave perfluoro-1-methyl-2-(1'-methylpropyl)cyclobut-1-ene (XVIII) and perfluoro-2-methyl-3-(1'-methylpropyl)buta-1,3-diene (XIX).Fluorination of XVIII over CoF3 gave perfluoro -1-methyl-2-(1'-methylpropyl)cyclobutane (XX), which on co-pyrolysis with bromine gave VI.XIX on heating gave XVIII.Reaction of XVIII with ammonia in ether gave a mixture of E and Z 1-trifluoromethyl-2-(1'-trifluoromethylpentafluoropropyliden-1'-yl)tetrafluorocyclobutylamine (XXI) which on diazotisation and hydrolysis afforded 2-(2'trifluoromethyltetrafluorocyclobut-1-en-1'-yl)-octafluorobutan-2-ol (XXII).