Mass Spectra of Some Tropolones and Tropolone Methyl Ethers

1972 ◽  
Vol 50 (6) ◽  
pp. 821-825 ◽  
Author(s):  
J. L. C. Wright ◽  
W. D. Jamieson ◽  
S. Safe ◽  
L. C. Vining
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Electron Impact ◽  
Mass Spectra ◽  
Formyl Radical ◽  
Sequential Loss ◽  
Ion Stability ◽  
Hydrogen Radical ◽  
Fragmentation Patterns ◽  
Competing Reactions

The mass spectra and fragmentation patterns of several tropolones and tropolone methyl ethers are reported. Deuteration studies confirmed that elimination of a formyl radical from 2-methoxytropone upon electron impact involves a specific rearrangement of the methoxyl group but sequential loss of carbon monoxide and a hydrogen radical from the ring are competing reactions. They also showed that in a dimethyl ether of anhydrosepedonin elimination of a formyl radical is completely suppressed. In the methyl ether of stipatatonic acid elimination of carbon monoxide is followed by expulsion of carbon dioxide with no loss of 29 mass units. The mass spectrum of [8-13C]-anhydrosepedonin as well as the energy spectrum for sepedonin have been investigated. These results not only provide a plausible account of the fragmentation of tropolones following electron impact but also illustrate the effect of product ion stability in determining which among a number of alternative modes of fragmentation will be more probable.

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.

Chemical Ionization Mass Spectrometry of Organophosphorus Insecticides

1974 ◽  
Vol 57 (5) ◽  
pp. 1050-1055 ◽  
Author(s):  
Roy L Holmstead ◽  
John E Casida
Keyword(s):  
Mass Spectrometry ◽  
Electron Impact ◽  
Mass Spectra ◽  
Chemical Structure ◽  
Chemical Ionization ◽  
Ionization Mass Spectrometry ◽  
Chemical Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Organophosphorus Insecticides ◽  
Fragmentation Patterns

Abstract The chemical ionization (CI) mass spectra of 15 important organophosphorus insecticides and 14 of their major metabolites are discussed in relation to the effect of chemical structure on fragmentation patterns. The fragments obtained with CI are sometimes quite different from those formed on electron impact and, in general, simpler spectra are obtained with CI.

Mass Spectra of Fifteen Chlorinated Aromatic Fungicides

1971 ◽  
Vol 54 (1) ◽  
pp. 178-186
Author(s):  
O Hutzinger ◽  
W D Jamieson ◽  
S Safe
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Chlorine Atoms ◽  
Fragmentation Patterns

Abstract Fragmentation patterns on electron impact of 15 chlorinated aromatic fungicides were investigated. In most cases strong molecular ions were obtained and the peak clusters due to the 35Cl and 37Cl isotopes and the number of chlorine atoms in the molecule were highly characteristic. Many of the polychlorinated fungicides give ions (e.g., C6Cl4, C6Cl3, C6Cl2, C6Cl, and C6 (CN)2) whose structures can be best represented as acyclic polyunsaturated moieties.

MASS SPECTRA OF OXYGENATED QUINOLINES

1966 ◽  
Vol 44 (7) ◽  
pp. 781-788 ◽  
Author(s):  
D. M. Clugston ◽  
D. B. MacLean
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Fragmentation Mechanism ◽  
Significant Extent ◽  
Fragmentation Pathways ◽  
Molecular Ion ◽  
One Step ◽  
The Stability ◽  
Hydroxy Compounds ◽  
Fragmentation Patterns

The mass spectra of the monohydroxyquinolines, the monomethoxyquinolines, N-methyl-2-quinolone, and N-methyl-4-quinolone have been recorded. The isomeric hydroxy compounds vary somewhat in the stability of the molecular ion, but all show the same fragmentation mechanism. Two general fragmentation patterns are discernible in the spectrum of each of the monomethoxyquinolines, but there is considerable variation among the isomers in the extent to which the two patterns occur. In addition, 8-methoxyquinoline undergoes a peculiar fragmentation wherein all three methyl hydrogens are lost. The 3-methoxy compound is unusual in that loss of 43 mass units from the molecular ion occurs in one step. Deuterium- and 13C-labelling experiments have proved to be useful in interpreting the fragmentation pathways. The spectra of the two N-methylquinolones prove that O to N methyl rearrangement does not occur to any significant extent upon electron impact.

Inelastic scattering of high energy electrons by atmospheric gases

1969 ◽  
Vol 47 (10) ◽  
pp. 1733-1774 ◽  
Author(s):  
Edwin N. Lassettre
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Inelastic Scattering ◽  
Electron Impact ◽  
Cross Sections ◽  
High Energy ◽  
Oscillator Strengths ◽  
Atmospheric Gases ◽  
High Energy Electrons ◽  
Forbidden Transitions

Inelastic scattering of electrons by nitrogen, oxygen, carbon monoxide, carbon dioxide, water, argon, and helium is reviewed. Electron impact spectra at both high (less than 40 keV) and low (greater than 15 eV) kinetic energies are presented and discussed. Collision cross sections and generalized oscillator strengths are described, when data are available, and the connection with optical oscillator strengths is discussed. The limiting selection rules which hold in the excitation of atoms and molecules by electron impact are discussed and typical examples of forbidden transitions are described.

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