The unimolecular decompositions of the metastable ions produced from 2,2,2-trifluoroethyl acetate, CH
3COOCH
2CF
3,
1, (
Mw: 142), 2,2,2-trifluoroethyl trifluoroacetate, CF
3COOCH
2CF
3,
2, (
Mw: 196), and
S-ethyl trifluorothioacetate, CF
3COSCH
2CH
3,
3, (
Mw: 158) upon electron ionization have been investigated by means of mass-analyzed ion kinetic energy (MIKE) spectrometry and D-labeling. The metastable ions
1+ decompose exclusively to give the ion at
m/z 122 by losing HF
via an 1,2-elimination.
In the normal mass spectrum of
2, no molecular ion is observed, while the ion corresponding to the loss of CF
3 gives rise to an intense peak at
m/z 127 (about 90% of the base peak) and the ion corresponding to the loss of F gives the peak at
m/z 177 with moderate intensity (about 20%). Both ions consist of two isomeric ions. Some interesting rearrangement processes, such as CF
3 or OCH
2CF
3 migration followed by the loss of a CO molecule, occur during the metastable fragmentations of these ions.
The molecular ion of
3, which is a base peak, decomposes into the ions at
m/z 89 and 61 by losing CF
3 and CF
3CO, respectively, in the metastable time region. The relative abundance of ions in the MIKE spectrum are rationalized with the thermochemical data estimated by the PM 3 method.
抄録全体を表示