Metastable Ions and Isotope Effects in the Mass Spectra of Methane and the Deuteromethanes

1971 ◽  
Vol 54 (9) ◽  
pp. 3834-3845 ◽  
Author(s):  
Lorin P. Hills ◽  
Marvin L. Vestal ◽  
Jean H. Futrell
Keyword(s):  
Mass Spectra ◽  
Isotope Effects ◽  
Metastable Ions

Electron impact studies. VI. Mass spectra of esters and thioesters. Skeletal rearrangement on electron impact

1967 ◽  
Vol 20 (4) ◽  
pp. 689 ◽  
Author(s):  
JH Bowie ◽  
RG Cooks ◽  
P Jakobsen ◽  
S Lawesson ◽  
G Schroll
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
High Resolution ◽  
Electron Impact ◽  
Mass Spectra ◽  
Skeletal Rearrangement ◽  
Unsaturated Esters ◽  
Impact Studies ◽  
Unsaturated Alcohols ◽  
Metastable Ions

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.

Squaraine chemistry. On the anomalous mass spectra of bis(4-dimethylaminophenyl)squaraine and its derivatives

1986 ◽  
Vol 64 (8) ◽  
pp. 1607-1619 ◽  
Author(s):  
Kock-Yee Law ◽  
F. Court Bailey ◽  
Lynn J. Bluett
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Mass Number ◽  
Equal Mass ◽  
Transfer Reactions ◽  
Ionization Mass ◽  
Structure Property ◽  
Fragment Ions ◽  
Structure Property Relationship ◽  
Metastable Ions

The electron impact (EI) mass specra of bis(4-dimethylaminophenyl)squaraine 1 and its derivatives 2–14 have been studied. Ions of mass number higher than the molecular ion, which are shown to be precursors of fragment ions of lower mass numbers, are observed. From the structure–property relationship, these ions are assigned to [Formula: see text] and [Formula: see text] where CH2R is the alkyl group in the N,N-dialkylanilino moiety of squaraine. Evidence is provided that the formation of [Formula: see text] and [Formula: see text] is the result of alkyl transfer and H transfer reactions within a squaraine aggregate rather than intermolecular vapor phase reactions in the mass spectrometer. This molecular aggregate is later shown to be a trimer by analysis of metastable ion data and chemical ionization mass spectrometry. The fragmentation sequence of this trimeric species is elucidated with the assistance of metastable ions. Results show that the trimer may break down to monomelic and dimeric species upon electron impact; alternatively, the four-membered ring of the central squaraine in the trimer may cleave to generate two species of approximately equal mass number. These two species usually dominate the mass spectrum and further fragment into [Formula: see text] and [Formula: see text] Detailed fragmentation schemes for [Formula: see text] and [Formula: see text] are proposed and discussed.

Spectroscopie de masse des gem-diesters cycliques. Fragment anhydride

1972 ◽  
Vol 50 (10) ◽  
pp. 1535-1538
Author(s):  
Krzysztof Jankowski ◽  
Jean Couturier ◽  
Jean-Yves Daigle
Keyword(s):  
Mass Spectra ◽  
Metastable Ions ◽  
Fragmentation Patterns

Mass spectra of four gem-diesters on three-, four-, five-, and six-member rings are analyzed. The fragmentation patterns of the investigated compounds supported by metastable ions are illustrated by Schemes 1–5 and Tables. A new fragment anhydride is proposed.

Detector for the Metastable Ions Observed in the Mass Spectra of Organic Compounds

1968 ◽  
Vol 39 (8) ◽  
pp. 1163-1167 ◽  
Author(s):  
N. R. Daly ◽  
A. McCormick ◽  
R. E. Powell
Keyword(s):  
Organic Compounds ◽  
Mass Spectra ◽  
Metastable Ions

Mechanism and structure in chemical ionization mass spectrometry: tricyclic flavanoid compounds

1973 ◽  
Vol 26 (7) ◽  
pp. 1577 ◽  
Author(s):  
JW Clark-Lewis ◽  
CN Harwood ◽  
MJ Lacey ◽  
JS Shannon
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Chemical Ionization ◽  
Ionization Mass Spectrometry ◽  
Chemical Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Fragmentation Pathways ◽  
Fragment Ions ◽  
Metastable Ions ◽  
Fragmentation Patterns

The chemical ionization mass spectra of a series of tricyclic flavanoid compounds have been examined using isobutane and hydrogen as reagent gases and the fragmen- tation modes have been correlated systematically in terms of structure. The technique produces simple fragmentation patterns and abundant metastable ions. The use of deuterium as reagent gas reveals the influence of extraneous water on the spectra and facilitates the interpretation of the fragmentation pathways. The fragment ions appear to arise from isomeric progenitors protonated at different sites in the molecules.

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