The mass spectrometric behaviour of some halogen-containing epoxyethers

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Eur. J. Mass Spectrom. 3, 37 - 48 (1997)

The mass spectrometric behaviour of some halogen-containing epoxyethers

Donata Favretto and Martina D'Alpaos
CNR, Area della Ricerca, Corso Stati Uniti 4, I-35020 Padova, Italy.
Pietro Traldi
CNR, Centro di Studio sulla Stabilita e Reattivita dei Composti di Coordinazione, Via F. Marzolo 1, I-35100 Padova, Italy.
Jean Pierre Begue, Daniele Bonnet-Delpon and Michael H. Rock,
CNRS, BIOCIS, Rue J. B. Clement, 92296 Chatenay-Malabry, France.

ABSTRACT:

The mass spectrometric behaviour of 1,2-epoxy-1-phenyl-2-ethoxy-3,3,3-trifluoropropane (1), 1,2-epoxy-1-phenyl-2-ethoxy-3,3-difluoro-3-chloropropane (2) and 2,3-epoxy-1-cyclohexyl-3-ethoxy-4,4,4-trifluorobutane (3) has been studied by means of electron impact and fast atom bombardment experiments. The decomposition pathways of odd electron molecular ions and protonated molecules have been studied by means of metastable ion spectra. Specific fragmentation channels are present for the three compounds; while for all the compounds, C₂H₅O^" loss is highly favoured, for 2 the ethyl radical loss becomes predominant. This has been justified by formation of a chloronium cation. Compound 3 only exhibits a product ion related to cleavage of the oxirane ring, suggesting that the lack of conjugation leads to labilisation of the oxirane ring. The protonated molecules partially decompose according to the structure of alkoxycarbenium ion already proposed in condensed phase. In the case of 1 the hydroxyl localization on C(2) has also been evidenced.

Keywords: Epoxyethers, fluorinated compounds, S_N2-like ring opening, alkoxy carbenium ion.

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