Chemistry of Heterocyclic Compounds

, Volume 21, Issue 12, pp 1368–1374 | Cite as

Negative ion mass spectra and structure of 4-substituted 1-phenyl-3-methyl-5-pyrazolones

  • A. I. Ermakov
  • A. A. Sorokin
  • V. G. Voronin


This is the first study of the electron capture dissociative resonance (ECDR) mass spectra of 4-substituted 1-phenyl-3-methyl-5=pyrazolones. The major features of the fragmentation of these compounds under ECDR. conditions were found relative to their substituent properties. After loss of the methyl group from the nitrogen atom, the pyrazolone ring isomerizes to a pyrazole ring with localization of the negative charge on the oxygen atom of the carbonyl group. The intensity of the [M - Ch3] fragment depends on the substituent properties.


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Copyright information

© Plenum Publishing Corporation 1986

Authors and Affiliations

  • A. I. Ermakov
    • 1
  • A. A. Sorokin
    • 1
  • V. G. Voronin
    • 1
  1. 1.Branch of the S. Ordzhonikidze All-Union Pharamaceutical Chemistry Research InstituteStaraya Kupavna

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