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.

IONIZATION AND DISSOCIATION OF FORMATE ESTERS BY ELECTRON IMPACT

1963 ◽  
Vol 41 (8) ◽  
pp. 2054-2059 ◽  
Author(s):  
D. Van Raalte ◽  
A. G. Harrison
Keyword(s):  
Formic Acid ◽  
Electron Impact ◽  
Proton Affinity ◽  
Mass Spectra ◽  
Methyl Formate ◽  
Ethyl Formate ◽  
Kcal Mole ◽  
Deuterium Labelling ◽  
Appearance Potential

The mass spectra of methyl formate-d, ethyl formate-d, and isopropyl formate-d are compared with the mass spectra of the undeuterated compounds. By use of the deuterium labelling and appearance potential studies the dissociation reactions leading to a number of the oxygen-containing ions have been elucidated. The proton affinity of formic acid is estimated to be 157 kcal/mole from the appearance potential of the HC(OH)2+ ion in the mass spectra of ethyl formate and isopropyl formate.

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.

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.

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.

Notizen: Hydrogen Scrambling in 1-Naphthol under Electron Impact

1972 ◽  
Vol 27 (11) ◽  
pp. 1681-1682
Author(s):  
L. Klasinc ◽  
H. Güsten
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Hydroxyl Group ◽  
Deuterium Labelling ◽  
Molecular Ion ◽  
Hydrogen Scrambling

Abstract The fragmentation of 1-naphthol and the scrambling of the hydroxyl group hydrogen under electron impact has been studied by means of deuterium labelling. The mass spectra of 1-naphthol (I), 1-naphthol-OD (II), 2,3,4,5,6,7,8-heptadeu-tero-1-naphthol (III) and perdeutero-1-naphthol (IV) indicate that only the hydrogen of the hydroxyl group is involved in the dehydration of the molecular ion. The loss of 29 mass units from the molecular ion yielding m/e 115 ([M-HCO·]) is pre-ceded by hydrogen scrambling to an extent of 25%, while in the further decomposition of the [M-HCO ]-ion complete hydrogen randomization is involved.

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.

AN ELECTRON IMPACT STUDY OF METHYL PHENYL ETHERS

1964 ◽  
Vol 42 (8) ◽  
pp. 2008-2017 ◽  
Author(s):  
F. Meyer ◽  
A. G. Harrison
Keyword(s):  
Electron Impact ◽  
Methyl Ether ◽  
Mass Spectra ◽  
Impact Study ◽  
Deuterium Labelling ◽  
Appearance Potential ◽  
Phenyl Ethers ◽  
Methyl Phenyl

The mass spectra of anisole, anisole-methoxy-d3, meta and para methylanisole, meta and para methyl-d3-anisole, and meta and para niethylanisole-methoxy-d3 have been recorded. From the deuterium labelling and appearance potential studies, the main fragmentation paths on electron impact have been elucidated. The energetics of formation of the CH3OC7H6+ ion from the methylanisoles, benzyl methyl ether, 7-methoxycycloheptatriene, and the ethylanisoles have been studied.

Mass spectra of 4,4-dimethyl-A-homo-4a,6-cholestadien-3-ols, 4,4-dimethyl-A-homo-5-cholestene-3,4a-diols and their derivatives

1982 ◽  
Vol 47 (10) ◽  
pp. 2768-2778
Author(s):  
Antonín Trka ◽  
Helena Velgová
Keyword(s):  
Carbon Atom ◽  
Electron Impact ◽  
Mass Spectra ◽  
Molecular Ions

Partial electron impact induced mass spectra are given of 3α-hydroxy-, 3β-hydroxy-, 3β-methoxy-, 3α-acetoxy- and 3β-acetoxy-4,4-dimethyl-A-homo-4a,6-cholestadienes, 3α,5α-epoxy-4,4-dimethyl-A-homo-5-cholestane, isomeric 4,4-dimethyl-A-homo-5-cholestene-3α(β),4aα(β)-diols, their 3-acetoxy derivatives and 3-methyl ethers. The fragmentation of the molecular ions of these substances involves the usual elimination of substituents (in the form of H2O, CH3OH, CH3COOH, CH2CO), but the most abundant and characteristic ions are products of the contraction of ring A (to a six- or five-membered one), accompanied by expulsion of a fragment containing the carbon atom C(4) with both methyls.

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