Metastable Ions ☆ | ScienceGate

The mass spectra of representative series of simple alkyl acetoacetates, alkyl acetothioacetates, and some unsaturated esters derived from unsaturated alcohols or phenols are reported and discussed. The fragmentation schemes have been established by high resolution measurements, appropriate metastable ions, and by deuterium and 18O labelling. Many of the spectra show significant skeletal rearrangement fragments arising from either loss of carbon monoxide or carbon dioxide.

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Translational energy release and stereochemistry of steroids. VIII-The mechanism of the elimination of water from metastable ions in epimeric 3-hydroxy steroids of the 5α-series

Organic Mass Spectrometry ◽

10.1002/oms.1210230605 ◽

1988 ◽

Vol 23 (6) ◽

pp. 453-459 ◽

Cited By ~ 11

Author(s):

Z. V. I. Zaretskii ◽

J. M. Curtis ◽

A. G. Brenton ◽

J. H. Beynon ◽

Carl Djerassi

Keyword(s):

Energy Release ◽

Translational Energy ◽

Metastable Ions

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Lifetime of heliumlike metastable ions measured

Physics Today ◽

10.1063/1.3022618 ◽

1971 ◽

Vol 24 (3) ◽

pp. 19-19

Author(s):

John T. Scott

Keyword(s):

Metastable Ions

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Metastable ions derived from triethylamine and benzylamine: Electron impact ionization compared to infrared multiple-photon dissociation

Chemical Physics Letters ◽

10.1016/0009-2614(83)80530-2 ◽

1983 ◽

Vol 97 (4-5) ◽

pp. 467-470 ◽

Cited By ~ 1

Author(s):

Yehuda Haas ◽

Chava Lifshitz

Keyword(s):

Electron Impact ◽

Impact Ionization ◽

Electron Impact Ionization ◽

Infrared Multiple Photon Dissociation ◽

Metastable Ions

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Detection of Metastable Ions With the Mass Spectrometer

Selected Scientific Papers of E.U. Condon ◽

10.1007/978-1-4613-9083-1_36 ◽

1991 ◽

pp. 496-498

Author(s):

J. A. Hipple ◽

E. U. Condon

Keyword(s):

Mass Spectrometer ◽

Metastable Ions

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Metastable Ions as a Guide to Reaction Mechanisms. Loss of ’OH from Substituted Nitrobenzene Molecular Ions

Zeitschrift für Naturforschung A ◽

10.1515/zna-1974-0323 ◽

1974 ◽

Vol 29 (3) ◽

pp. 507-512

Author(s):

T. Keough ◽

J. H. Beynon ◽

R. G. Cooks ◽

C. Chang ◽

R. H. Shapiro

Keyword(s):

Nitro Group ◽

Hydrogen Transfer ◽

Direct Interaction ◽

Kinetic Energy Release ◽

Molecular Ions ◽

Time Range ◽

Direct Role ◽

Ion Fragmentation ◽

Distinct Process ◽

Metastable Ions

Loss of ‘OH from the molecular ions of nitrobenzenes having various substituents in the m- and p-positions does not involve substituent randomization and reaction through the ortho-isomer; the kinetic energy release accompanying metastable ion fragmentation shows this latter to be an entirely distinct process. The origin of the hydrogen lost as 'OH in the m- and p-compounds is the ring (mainly the position ortho to the nitro group in methyl p-nitrobenzoate). However, the hydrogens of the substituent do play a direct role in the reaction as shown by an isotope effect upon the abundances of metastable peaks. Hydrogen atom abstraction by the ionized nitro group apparently occurs independently of participation by the substituent on the nitrobenzene but a second hydrogen transfer from this substituent to the ring precedes fragmentation. Direct interaction between groups o ' the aromatic ring that are not ortho to each other therefore apparently does not occur. Inversion of the rate constants for two reactions, NO' loss and CH2O loss from the methyl p-nitrobenzoate molecular ion in the metastable ion time range, has been observed following isotopic substitution.

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