Unimolecular Metastable Decomposition of Bis(2,2,2-trifluoroethyl) Ether, CF₃CH₂OCH₂CF₃, and Ethyl 2,2,2-Trifluoroethyl Ether, CH₃CH₂OCH₂CF₃, upon Electron Ionization

抄録

The unimolecular metastable decompositions of bis(2,2,2-trifluoroethyl) ether, CF₃CH₂OCH₂CF₃ (1), and ethyl 2,2,2-trifluoroethyl ether, CH₃CH₂OCH₂CF₃ (2), induced by electron ionization, have been investigated by mass-analyzed ion kinetic energy (MIKE) spectrometry and energy-dependent collision-induced dissociation (CID) spectra in conjunction with thermochemical data. In the metastable time window, the molecular ions of 1 decompose into the ions at m/z 113 by the loss of CF3 and m/z 83 by the consecutive losses of CF3 and CH₂O, while those of 2^{+ •} decompose into the ions at m/z 113 and m/z 59 by the elimination of CH3 and CF3 , respectively. The decomposition of the latter fragment ion is similar to that of the m/z 59 ion from the corresponding fluorine-free analogue, diethyl ether, CH₃CH₂OCH₂CH₃ (3), that is, fragment ions m/z 41 and m/z 31 are observed, which correspond to the competitive losses of H₂O and C₂H₄, respectively. The metastable ions m/z 113 from 1^{+ •} and 2^{+ •} decompose in a variety of ways: in addition to the fragment ion m/z 65, which is generated by the elimination of CHFO, four other fragment ions with m/z 83, 63, 61, and 31 are observed , which correspond to the competitive losses of CH₂O, (CH₂O+HF), CH₂F₂, and C₂HF₃ (or C₂H₄F₂O), respectively.