The mass spectra of [18]annulene derivatives. Skeletal rearrangement upon electron impact

1967 ◽  
Vol 20 (12) ◽  
pp. 2669 ◽  
Author(s):  
GM Badger ◽  
JH Bowie ◽  
JA Elix ◽  
GE Lewis ◽  
UP Singh
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Skeletal Rearrangement ◽  
Rearrangement Processes

The mass spectra of a series of [18]annulene derivatives are reported and discussed. The majority of fragmentation modes exhibited in these spectra are produced by well-defined skeletal reorganization. In the case of one compound, all the observed fragmentations occur as the result of skeletal rearrangement processes. This appears to be the first reported example of such a phenomenon.

Electron impact studies. XXXI. Skeletal-rearrangement fragments in the mass spectra of anils

1968 ◽  
Vol 21 (8) ◽  
pp. 2021 ◽  
Author(s):  
JH Bowie ◽  
RG Cooks ◽  
JW Fisher ◽  
T McL Spotswood
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Electron Impact ◽  
Mass Spectra ◽  
General Type ◽  
High Resolution Mass Spectrometry ◽  
Aromatic Aldehydes ◽  
Skeletal Rearrangement ◽  
Rearrangement Processes ◽  
Resolution Mass

Skeletal-rearrangement fragments are observed in the mass spectra of all anils derived from aromatic aldehydes. The rearrangement processes have been studied by high-resolution mass spectrometry and in certain cases by deuterium labelling. All processes are of the general type [ABC]+ → [AC]+ +B.

Some skeletal-rearrangement processes of phosphoranes upon electron impact

1970 ◽  
Vol 23 (2) ◽  
pp. 307 ◽  
Author(s):  
AP Gara ◽  
RA Massy-Westropp ◽  
JH Bowie
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Bond Formation ◽  
Skeletal Rearrangement ◽  
Deuterium Labelling ◽  
Rearrangement Processes

The mass spectra of acyl phosphoranes exhibit peaks which arise by P-O bond formation. The problem of thermal against electron impact rearrangement is considered and the rearrangements have been studied by deuterium labelling. The formation of the fluorenyl cation (m/e 165) has also been investigated.

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. 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.

Electron impact studies. XXXII. Negative-ion mass spectra of aromatic compounds containing the =N-O- substituent

1968 ◽  
Vol 21 (8) ◽  
pp. 2031 ◽  
Author(s):  
JH Bowie ◽  
SO Lawesson ◽  
BS Larse ◽  
GE Lewis ◽  
G Schroll
Keyword(s):  
Electron Impact ◽  
Aromatic Compounds ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Negative Ion ◽  
Skeletal Rearrangement ◽  
Marked Contrast ◽  
Azoxy Compounds ◽  
Positive Ion ◽  
Fragmentation Processes

The negative-ion mass spectra of aromatic azoxy compounds, nitrones, and N-oxides exhibit pronounced molecular ions and simple fragmentation processes. No skeletal-rearrangement fragments are produced upon electron impact, in marked contrast to those exhibited in the positive-ion spectra of these compounds.

Mass spectra of substituted thioglycollic acids and esters. Skeletal rearrangement upon electron-impact

1969 ◽  
Vol 2 (4) ◽  
pp. 413-424 ◽  
Author(s):  
J. H. Bowie ◽  
J. Ø. Madsen ◽  
S.-O. Lawesson ◽  
R. G. Cooks
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Skeletal Rearrangement

Synthesis of 1,3-dihydro-2H-benzo-1,4-diazepin-2-ones and 1,2-dihydropyrazin-2-ones via iminophosphoranes. Mass spectra of 1,5-disubstituted-1,2-dihydropyrazin-2-ones

1979 ◽  
Vol 57 (20) ◽  
pp. 2696-2702 ◽  
Author(s):  
Jack Ackrell ◽  
Edvige Galeazzi ◽  
Joseph M. Muchowski ◽  
Laszolo Tökés
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Skeletal Rearrangement ◽  
Molecular Ion ◽  
Phenyl Derivative ◽  
Mild Conditions

The azido ketones 4c–e and 10a–d reacted with triphenylphosphine under mild conditions to give the benzo-1,4-diazepin-2-ones 7c–e and the 1,2-dihydropyrazin-2-ones 12a–d, respectively.The electron impact induced fragmentation of the 1,5-disubstituted-1,2-dihydropyrazin-2-ones was shown to occur by extensive skeletal rearrangement. The 1,5-diaryl derivatives 12a–c fragmented via 1,4-diarylimidazole species produced by the expulsion of CO from the molecular ion. In contrast, the 1-cyclohexyl-5-phenyl derivative 12d fragmented almost entirely via a 2-hydroxypyrazine intermediate derived from the molecular ion by McLafferty cleavage.

Hydroxamic acids. III. Mass spectra of substituted hydroxamic acids and cyclic imides

1969 ◽  
Vol 22 (1) ◽  
pp. 175 ◽  
Author(s):  
JH Bowie ◽  
MTW Hearn ◽  
AD Ward
Keyword(s):  
Electron Impact ◽  
Hydroxamic Acid ◽  
Mass Spectra ◽  
Hydroxamic Acids ◽  
Skeletal Rearrangement ◽  
Cyclic Imides ◽  
Derivatives Of ◽  
Hydroxamic Acid Derivatives

Aryl hydroxamic acid derivatives fragment in a diagnostic manner upon electron impact. A hydroxamic acid containing both styryl and benzyl substituents undergoes skeletal-rearrangement of the type ABC → AC+B. The mass spectra of the O- and N-acetyl derivatives of O- benzylhydroxamic acids are indistinguishable. M-CO2 fragments are again observed in the mass spectra of several substituted phthalimides.

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