Thermal gas-phase reaction of perfluorobuta-1,3-diene with NO2

The reaction of NO2 with perfluorobuta-1,3-diene, CF2CFCFCF2 (C4F6), has been studied at 312.9, 323.0, 333.4, 396.0 and 418.0 K, using a conventional static system. The products formed in the temperature range 312.9–333.4 K were CF2CFCF(NO2)CF2(NO2) (I), CF2(NO2)CFCFCF2(NO2) (II), CF2CFCF(NO2)C(O)F (III) and CF2(NO2)CFCFC(O)F (IV) and FNO. The formation of these compounds was detected performing infrared and Raman spectra. The infrared spectrum shows a band at 1785 cm−1, characteristic to the terminal –CFCF2 group and the Raman spectrum shows a band located at 1733 cm−1, corresponding to –CFCF– group. It indicates, that in this temperature range, NO2 attacks initially only one double bound of CF2CFCFCF2. Since the intermediate radical CF2CFCFCF2(NO2) formed in this process is allylic in nature, so there is no isomerization involved in this process, but rather the allylic radical is able to add the second NO2 either to CF2 or CFCF2(NO2) end, forming the corresponding products. At 396.0 and 418.0 K different products were observed: CF2(NO2)CF(NO2)C(O)F (V), NO, CF3C(O)F, C(O)F2 and traces of epoxide of tetrafluoroethene, showing that, at these temperatures, both double bonds are attacked by NO2 and detachment of CF2 group is produced. The mechanisms consistent with experimental results in the temperature range 312.9–333.4 and at 396.0 and 418 K are proposed.