ADDITION OF 1,2-DIBROMO-1-CHLOROTRIFLUOROETHANE TO CHLOROTRIFLUOROETHYLENE INDUCED BY UV-RADIATION. SYNTHESIS OF PERFLUORO-1,3-BUTADIENE AND PERFLUORO-1,3,5-HEXATRIENE

Article abstract of DOI:10.1016/S0022-1139(00)81263-4

Photochemically initiated reaction of 1,2-dibromo-1-chlorotrifluoroethane (II) with chlorotrifluoroethylene (I) gave 38percent 1,4-dibromo-2,3-dichlorohexafluorobutane (III) and 19percent 1,6-dibromo-2,3,5-trichlorononafluorohexane (IV) in addition to the higher telomers.Dehalogenations of III and IV yielded perfluoro-1,3-butadiene (VI) and perfluoro-1,3,5-hexatriene (VIII) with 3-chlorononafluoro-1,5-hexadiene (VII), respectively.Photochemical reduction of butane III with 2-propanol resulted in a preferential reduction of C-Br bonds, and from 2,3-dichloro-1,1,2,3,4,4-hexafluorobutane (IX) thus formed, esters of difluoroacetic acid were prepared by dehalogenation of IX and subsequent oxidation and esterification of the product.The photochemical reduction of hexane IV gave a mixture of 79percent trichlorononafluorohexane XII and 21percent dichlorononafluorohexane XIII.The mechanism of formation of the unusual products of the title addition reaction is discussed.