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.

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. 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. 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. 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.

Electron impact studies. XI. Mass spectra of aromatic azoxy compounds. Skeletal rearrangement upon electron impact

1967 ◽  
Vol 20 (8) ◽  
pp. 1601 ◽  
Author(s):  
JH Bowie ◽  
RG Cooks ◽  
GE Lewis
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Skeletal Rearrangement ◽  
Impact Studies ◽  
Azoxy Compounds

The mass spectra of 15 aromatic azoxy compounds are reported and discussed. The spectra exhibit pronounced molecular ions, and fragmentation modes which are produced by both simple cleavage and complex skeletal reorganization processes.

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. XL. Negative-ion mass spectra of organosulphur compounds : Thioglycollic acids and arylsulphinylamines

1969 ◽  
Vol 22 (1) ◽  
pp. 153 ◽  
Author(s):  
JH Bowie ◽  
F Duus ◽  
S Lawesson ◽  
FCV Larsson ◽  
J+ Madsen
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Negative Ion ◽  
Skeletal Rearrangement ◽  
Marked Contrast ◽  
Impact Studies ◽  
Positive Ion ◽  
Hydrogen Rearrangement

The negative-ion mass spectra of thioglycollic esters and S- alkylthioglycollic acids exhibit ions produced by simple cleavage and/or cleavage with hydrogen rearrangement. Similar spectra of arylsulphinylamines show pronounced molecular ions together with simple cleavage fragments. No skeletal-rearrangement fragments are present in the negative-ion spectra, in marked contrast with those observed in the corresponding positive-ion spectra.

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.

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