Mass spectrometric study of vacuum pyrolysis of perfluoroolefins
The primary products of vacuum pyrolysis of tetrafluoroethylene, hexafluoropropene, pentafluoro-2-chloropropene, octafluoroisobutene, octafluorobutene-1, octafluorobutene-2, and perfluoro-2,3-dimethylbutene were studied by mass spectrometry.
The coincidence of the basic fragmentary ions in the mass spectra of perfluoropropene, pentafluoro-2-chloropropene, perfluorobutenes, and perfluoro-2,3-dimethylbutene with the primary products of their vacuum pyrolysis indicates the absence of rearrangements of the molecular radical cations contained as substituents at the double bond of the F atom or CF3 group and permits predicting the primary act of thermal decomposition of perfluoroolefins with the mass spectra obtained with a low ionizing voltage.
The fragmentation changes in the low-energy mass spectra of hexafluoropropene, pentafluoro-2-chloropropene, and perfluoroisobutene confirmed that not olefin-carbene isomerization, but their decomposition, which takes place with the possible participation of 1,3-biradicals, is the predominant process with an increase in the temperature in conditions of vacuum pyrolysis.
KeywordsMass Spectrum Thermal Decomposition Radical Cation Tetrafluoroethylene Molecular Radical
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