Novel CFCs-substitutes recommended by EPA (hydrofluorocarbon-245fa and hydrofluoroether-7100): Ion chemistry in air plasma and reactions with atmospheric ions

  • Ester Marotta
  • Cristina Paradisi
  • R. Graham Cooks
Articles

Abstract

The ion chemistry of the title compounds, a nonafluorobutyl methyl ether and a hydrofluoropropane, is elucidated by a combination of studies using atmospheric pressure ionization mass spectrometry and triple quadrupole mass spectrometry. In the positive ion mode, the hydrofluoroether readily forms an [M−F]+ ion, attributable to hydronium ion induced dehydrofluorination, the product of which can be further hydrated to give a protonated hydrofluoroester. By contrast, the hydrofluoropropane does not react with the hydronium ion but rather gives hydrofluoroalkenylium cations via H atom and F atom abstraction by the dioxygen radical cation. In the negative ion mode, the fluorobutyl methyl ether undergoes dissociative electron capture with O2−·, O2−·(H2O), O3−·, and NO2 to generate the fluorobutoxy anion, which can dissociate by CF2=O loss to give the perfluorocarbanion when the precursor ions are internally excited. The hydrofluoropropane reacts readily with common atmospheric anions to form molecular complexes with F, O2−·, and O3−· and the strongly H-bonded species, O2−·(HF) and F(HF). Interestingly, isomeric pentafluoropropanes form in the reaction with O2−·, either O2−·(HF) or F(HF), depending on the specific pattern of the fluoro substitution.

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Copyright information

© American Society for Mass Spectrometry 2005

Authors and Affiliations

  • Ester Marotta
    • 1
    • 2
  • Cristina Paradisi
    • 1
  • R. Graham Cooks
    • 2
  1. 1.INTM del CNR—Sezione di Padova, Dipartimento di Scienze ChimicheUniversità di PadovaPadovaItaly
  2. 2.Department of ChemistyPurdue UniversityWest LafayetteUSA
  3. 3.Dipartamento di Scienze ChimicheUniversità di PadovaPadovaItaly

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