The mass spectrometric behaviour of two trifluoromethyl-substituted 4,5-dihydro-3H-pyrazoles and of their corresponding regioisomers 4,5-dihydro-1H-pyrazoles has been studied and compared with that of two non-fluorinated analogues. Electron-impact experiments, together with metastable ion studies and accurate mass measurements, evidenced many different fragmentation processes. Among them, the mechanism(s) related to the loss of the trifluoromethyl radical from the molecular ion proved to be particularly interesting, due to the observation of a composite metastable peak. An interesting retrosynthetic process was detected among the decomposition routes involving ring fission.
Electron-impact Mass-spectrometry of Trifluoromethyl-substituted 4,5-dihydro-1h-pyrazoles and 4,5-dihydro-3h-pyrazoles
FAVRETTO, DONATA;
1992
Abstract
The mass spectrometric behaviour of two trifluoromethyl-substituted 4,5-dihydro-3H-pyrazoles and of their corresponding regioisomers 4,5-dihydro-1H-pyrazoles has been studied and compared with that of two non-fluorinated analogues. Electron-impact experiments, together with metastable ion studies and accurate mass measurements, evidenced many different fragmentation processes. Among them, the mechanism(s) related to the loss of the trifluoromethyl radical from the molecular ion proved to be particularly interesting, due to the observation of a composite metastable peak. An interesting retrosynthetic process was detected among the decomposition routes involving ring fission.Pubblicazioni consigliate
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