Polyfluoroalkyl derivatives of nitrogen. Part XLII. Reaction of N-bromobistrifluoromethylamine with 1H-pentafluoropropene and some further studies on the thermal rearrangement of NN-bistrifluoromethyl-vinylamines

Abstract

N-Bromobistrifluoromethylamine reacts with a 95 : 5 mixture of cis- and trans-1H-pentafluoropropene under free-radical conditions to give a high yield of a mixture of erythro- and threo-2-bromo-1,2,3,3,3-pentafluoro-NN-bistrifluoromethylpropylamine in the ratio 62 : 38. Dehydrobromination of the erythro-isomer affords a mixture of cis- and trans-1,2,3,3,3-pentafluoro-NN-bistrifluoromethylprop-1-enylamine in the ratio 38 : 62 whereas the threo-isomer yields the cis-olefin exclusively. The static pyrolysis of perfluoro-(NN-dimethylvinylamine) at 500 °C affords perfluoro-2-azapent-2-ene in reasonable yield, together with hexafluoroethane and other decomposition products. Pyrolysis in the presence of an excess of toluene gives trifluoromethane and only a low yield of the azapent-2-ene. Similarly 1,2-difluoro-NN-bistrifluoromethylvinylamine affords 4H-octafluoro-2-azapent-2-ene on pyrolysis, but 2-bromo-1,2-difluoro-NN-bistrifluoromethylvinylamine and NN-bistrifluoromethylvinylamine give mainly decomposition products.