Electron impact studies. XLVIII. Specific hydrogen-rearrangements in the mass spectra of ortho-alkoxyanils

1969 ◽  
Vol 22 (6) ◽  
pp. 1219 ◽  
Author(s):  
JH Bowie ◽  
PJ Hoffmann
Keyword(s):  
Electron Impact ◽  
Aromatic Ring ◽  
Mass Spectra ◽  
Bond Cleavage ◽  
Aromatic Rings ◽  
Hydrogen Atoms ◽  
Deuterium Labelling ◽  
Alkoxyl Group ◽  
Impact Studies

The mass spectra of anils with ortho-alkoxyl substituents in the aromatic ring derived from the aldehyde contain pronounced peaks prod- uced by C=N bond cleavage accompanied by one and/or two hydrogen transfers to the nitrogen-containing fragment. Deuterium-labelling studies show that the hydrogen atoms involved are those attached to the α-carbon (α to oxygen) of the alkoxyl group. The extent of the hydrogen rearrangements may be altered by the addition of further substituents to the aromatic rings.

Electron impact studies. XXXVII. Skeletal-rearrangement fragments in the mass spectra of alkyl and aryl isoxazoles

1969 ◽  
Vol 22 (3) ◽  
pp. 563 ◽  
Author(s):  
JH Bowie ◽  
RKMR Kallury ◽  
RG Cooks
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Skeletal Rearrangement ◽  
Deuterium Labelling ◽  
Isoxazole Ring ◽  
Impact Studies ◽  
Rearrangement Processes

The mass spectra of substituted isoxazoles are reported and discussed. The spectra of isoxazoles are strikingly different from those of oxazoles because the initial fragmentations of isoxazoles involve N-O bond fission. Specific skeletal-rearrangement processes are observed in many spectra, and it is proposed that they proceed through azirine and oxazole intermediates. Certain fragmentations have been studied by deuterium labelling. The hydrogens attached to an isoxazole ring do not randomize with the hydrogens of the methyl and phenyl substituents.

Electron impact studies. II. Mass spectra of quercetagetin derivatives

1966 ◽  
Vol 19 (9) ◽  
pp. 1627 ◽  
Author(s):  
JH Bowie ◽  
DW Cameron
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Mass Measurements ◽  
Exact Mass ◽  
Deuterium Labelling ◽  
Impact Studies ◽  
Metastable Ions ◽  
Fragmentation Processes

The mass spectra of 11 quercetagetin derivatives are reported and discussed. The spectra are generally simple and amenable to analysis. 4 number of fragmentation processes have been substantiated by exact mass measurements, appropriate metastable ions, and deuterium labelling.

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.

ENERGETICS AND MECHANISM OF HYDRONIUM ION FORMATION BY ELECTRON IMPACT

1963 ◽  
Vol 41 (12) ◽  
pp. 3118-3126 ◽  
Author(s):  
D. Van Raalte ◽  
A. G. Harrison
Keyword(s):  
Water Molecule ◽  
Electron Impact ◽  
Proton Affinity ◽  
Mass Spectra ◽  
Kcal Mole ◽  
Deuterium Labelling ◽  
Ion Formation ◽  
Hydronium Ion

The reactions leading to formation of the hydronium ion in the mass spectra of a number of alcohols and formate esters have been elucidated through a study of appearance potentials and metastable transitions and by the use of deuterium labelling. The results lead to ΔHf(H3O+) = 157 ± 3 kcal/mole corresponding to a proton affinity of the gaseous water molecule of 151 ± 3 kcal/mole.

AN ELECTRON IMPACT STUDY OF SOME C8HI0 ISOMERS

1965 ◽  
Vol 43 (1) ◽  
pp. 211-218 ◽  
Author(s):  
F. Meyer ◽  
P. Haynes ◽  
Stewart McLean ◽  
A. G. Harrison
Keyword(s):  
Mass Spectrum ◽  
Electron Impact ◽  
Mass Spectra ◽  
Major Part ◽  
The Other ◽  
Fragmentation Pattern ◽  
Impact Study ◽  
Deuterium Labelling ◽  
Appearance Potential ◽  
Alkyl Benzenes

The mass spectra of 1-, 2-, and 6-methylspiro[2.4]hepta-1,3-diene have been measured and found to be very similar to the spectra of 7-methylcycloheptatriene and the isomeric alkyl benzenes. It is concluded that in all cases the major part of the fragmentation occurs by identical paths involving identical intermediates. This conclusion is supported by deuterium labelling and appearance potential data. On the other hand the mass spectrum of 2,5-dimethyl-1,5-hexadien-3-yne, an acyclic C8H10 isomer, shows a number of significant differences in its fragmentation pattern. These differences are reflected in the energetics of ion formation and it is concluded that in this case the fragmentation proceeds through different intermediates.

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