Combined deuterium labeling and appearance potential measurements to uncover competing reaction mechanisms in the electron-impact-induced loss of water from cyclohexanol

1975 ◽  
Vol 10 (8) ◽  
pp. 679-681 ◽  
Author(s):  
Mark M. Green ◽  
Don Bafus ◽  
J. L. Franklin
Keyword(s):  
Electron Impact ◽  
Reaction Mechanisms ◽  
Deuterium Labeling ◽  
Appearance Potential

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.

Appearance potential and electron impact ionisation cross-section of C60

1992 ◽  
Vol 114 (1-2) ◽  
pp. R1-R8 ◽  
Author(s):  
M. Sai Baba ◽  
T.S. Lakshmi Narasimhan ◽  
R. Balasubramanian ◽  
C.K. Mathews
Keyword(s):  
Electron Impact ◽  
Cross Section ◽  
Appearance Potential ◽  
Ionisation Cross Section ◽  
Impact Ionisation

Fragmentation of isomeric dideoxy derivatives of 1,6-anhydro-β-D-hexopyranoses under electron impact

1981 ◽  
Vol 46 (10) ◽  
pp. 2390-2403 ◽  
Author(s):  
František Tureček ◽  
Tomáš Trnka ◽  
Miloslav Černý
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Hydroxyl Group ◽  
Fragmentation Pattern ◽  
Positional Isomers ◽  
Deuterium Labeling ◽  
Stereochemical Assignment ◽  
Electron Impact Mass ◽  
Derivatives Of ◽  
Impact Mass

Electron impact mass spectra of all possible dideoxy derivatives of 1,6-anhydro-β-D-hexopyranoses and their sixteen specifically deuterium-labeled derivatives are reported. The spectra of positional isomers differ considerably making possible the reliable location of the hydroxyl group by mass spectrometry. The configuration of the hydroxyl group at C(2) and C(4) has only a negligible effect on the fragmentation pattern of stereoisomers. However, mass spectra of the C(3)-configurational isomers differ sufficiently to permit a stereochemical assignment. The fragmentation paths were elucidated by means of deuterium labeling and metastable spectra.

Mass Spectrometry in Structural and Stereochemical Problems. CCXVII. Electron Impact Promoted Fragmentation of O-Methyl Oximes of some α,β-Unsaturated Ketones and Methyl Substituted Cyclohexanones

1972 ◽  
Vol 50 (17) ◽  
pp. 2776-2785 ◽  
Author(s):  
Younus M. Sheikh ◽  
Raymond J. Liedtke ◽  
A. M. Duffield ◽  
Carl Djerassi
Keyword(s):  
Mass Spectrometry ◽  
Electron Impact ◽  
High Resolution Mass Spectrometry ◽  
Unsaturated Ketone ◽  
Deuterium Labeling ◽  
Oxime Ether ◽  
Ether Group ◽  
Unsaturated Ketones ◽  
Carbonyl Derivatives ◽  
Mass Spectrometric Fragmentation

Deuterium labeling and high resolution mass spectrometry have been utilized to delineate the modes of mass spectrometric fragmentation of O-methyl oximes of α,β-unsaturated ketones and methyl substituted cyclohexanones. α,β-Unsaturated ketone and 2- and 4-methylcyclohexanone O-methyl oxime ether derivatives fragment upon electron impact in a manner reminiscent of the carbonyl derivatives from which they were prepared. However, several fragmentation sequences characteristic of the O-methyl oxime ether group were observed.

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.

Charge localization and the electron-impact fragmentation of carbonyl compounds

1967 ◽  
Vol 20 (11) ◽  
pp. 2387 ◽  
Author(s):  
JL Occolowitz
Keyword(s):  
Electron Impact ◽  
Carbonyl Group ◽  
Carbonyl Compounds ◽  
Charge Retention ◽  
Charge Localization ◽  
Appearance Potential ◽  
Impact Fragmentation ◽  
Group Structures ◽  
Hydrocarbon Fragment

Ionization and appearance potential measurements on aliphatic and ω- phenyl carbonyl compounds show that electron-impact fragmentation of these compounds α and β to the carbonyl group resulting in charge retention on the hydrocarbon fragment can occur without ionization of the carbonyl group. Structures are assigned to ionic and neutral fragments on the basis of their enthalpies, and evidence is presented favouring the elimination of the neutral enol forms of acetone and acetaldehyde in the hydrogen-rearranged β fission of ketones and aldehydes.

AN ELECTRON IMPACT STUDY OF CHLOROMETHYL AND DICHLOROMETHYL DERIVATIVES

1962 ◽  
Vol 40 (9) ◽  
pp. 1730-1737 ◽  
Author(s):  
A. G. Harrison ◽  
T. W. Shannon
Keyword(s):  
Mass Spectrum ◽  
Electron Impact ◽  
Methyl Chloride ◽  
Heat Of Formation ◽  
Mass Spectrometric ◽  
Spectrometric Method ◽  
Mass Spectrometric Method ◽  
Impact Study ◽  
Kcal Mole ◽  
Appearance Potential

The appearance potential of the CH2Cl+ ion has been measured from methyl chloride, dichloromethane, bromochloromethane, and ethyl chloride. The results lead to ΔHf(CH2Cl+) = 230 ± 3 kcal/mole. The heat of formation of CHCl2+ is estimated to be 215 ± 3 kcal/mole from the appearance potential of this ion in the mass spectrum of chloroform and of bromodichloromethane. By the indirect mass spectrometric method ΔHf(CH2Cl) = 29 ± 3 kcal/mole and ΔHf(CHCl2) = 15 ± 3 kcal/mole are obtained. The ionization potentials of a number of chlorine-containing compounds have been measured.

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