Rearrangements in the Molecular Ions of Some ortho-Substituted Schiff Bases

1993 ◽  
Vol 46 (6) ◽  
pp. 895 ◽  
Author(s):  
T Blumenthal ◽  
M Dosen ◽  
RG Gillis ◽  
QN Porter
Keyword(s):  
Kinetic Energy ◽  
Schiff Bases ◽  
Molecular Ions ◽  
Energy Spectra ◽  
Supporting Evidence ◽  
Deuterium Labelling ◽  
Methyl Group ◽  
Molecular Ion ◽  
Fragment Ions ◽  
Ion Kinetic Energy

Under electron ionization conditions, the ortho-substituted Schiff bases N-benzylidene-o-toluidine (1a), N-(o-methylbenzylidene)aniline (1b), N-salicylideneaniline (1c) and N-(o-methoxybenzylidene)aniline (1d) give fragment ions which have been shown by collision-activated mass-analysed ion kinetic energy spectra to have the structure of the protonated molecular ions of indole (2), benzofuran (3), and 1,2-benzisoxazole (4). The molecular ion of N-(o-methylbenzylidene)-o-toluidine (1f) gives as fragment ions not only the protonated molecular ion (2) of indole and the tropylium ion but also the molecular ion of anthracene. Attempts to find supporting evidence for a mechanism for this rearrangement by deuterium labelling of a methyl group in (1b), such as (1g), have been unsuccessful.

The Electron Impact Induced Fragmentation of 1-Aryl-5-hydroxy-1,2,3-triazole-4-carboxamides

1990 ◽  
Vol 43 (12) ◽  
pp. 2021 ◽  
Author(s):  
AT Lebedev ◽  
TY Samguina ◽  
T Blumenthal ◽  
MY Kolobov
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Kinetic Energy ◽  
Electron Impact ◽  
High Resolution Mass Spectrometry ◽  
Energy Spectra ◽  
Molecular Ion ◽  
High Resolution Mass ◽  
Ion Kinetic Energy ◽  
Resolution Mass

The pathways of the electron impact induced fragmentation of 1-aryl-5- hydroxy-1,2,3-triazole-4-carboxamides were studied. The compositions of the key ions were confirmed by high-resolution mass spectrometry. The proposed pathways were established from mass analysed ion kinetic energy spectra, and B/E and B2/E linked scans. A variety of structures for the molecular ion of the title compounds is proposed.

Ion–Molecule Reactions in Methyl Fluoride and Methyl Chloride

1971 ◽  
Vol 49 (13) ◽  
pp. 2217-2222 ◽  
Author(s):  
A. A. Herod ◽  
A. G. Harrison ◽  
N. A. McAskill
Keyword(s):  
Kinetic Energy ◽  
Methyl Chloride ◽  
Molecular Ions ◽  
Rate Coefficients ◽  
Minor Importance ◽  
Methyl Fluoride ◽  
Ion Molecule Reactions ◽  
Fragment Ions ◽  
Ion Energies ◽  
Ion Kinetic Energy

The reactions of the molecular ion have been studied as a function of the ion kinetic energy for methyl fluoride and methyl chloride. The following reactions are observed[Formula: see text]For methyl fluoride (X = F) reactions c and d have kinetic energy thresholds and become significant at high ion energies. For CH3Cl (X = Cl) reaction a is not observed and reactions c and d are of only minor importance at high ion energies. Rate coefficients for the molecular ions and a number of fragment ions as well as rate coefficients for further reaction of CH4X+ are reported.

Mass spectral investigations on selenium compounds. II. The behaviour of meta-and para-substituted benzeneseleninic acids and of meta-nitrophenyl selenocyanate under electron impact

1982 ◽  
Vol 35 (7) ◽  
pp. 1365 ◽  
Author(s):  
A Benedetti ◽  
C Preti ◽  
L Tassi ◽  
G Tosi
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectrum ◽  
Electron Impact ◽  
Molecular Ions ◽  
Selenium Compounds ◽  
Molecular Ion ◽  
Mass Spectral ◽  
Low Intensity ◽  
Fragment Ions

Substituted benzeneseleninic acids of the type XC6H4SeO2H (X = m-Cl, p-Cl, m-Br, p-Br, p-Me, m-NO2, p-NO2) have been investigated by mass spectrometry. The fragmentation modes and the fragment ions are discussed and compared with those obtained from the mass spectrum of m-nitro-phenyl selenocyanate, O2NC6H4SeCN. Generally, as regards the acids, besides very weak peaks due to the molecular ions, a number of peaks at higher mass numbers and of greater intensity is observed; these peaks are in multiplets typical of the presence of two selenium atoms, and they correspond to the disubstituted diphenyl diselenides of the type XC6H4SeSeC6H4X. m-Nitrophenyl selenocyanate shows an intense molecular ion peak and the relative fragmentation, while the peak due to the diselenide is of very low intensity.

Angle-dependence of ion kinetic energy spectra obtained by using mass spectrometers II. Experimental considerations and preliminary results on non-fragmenting systems

1984 ◽  
Vol 392 (1802) ◽  
pp. 89-106 ◽  
Keyword(s):  
Kinetic Energy ◽  
Energy Analysis ◽  
Energy Spectra ◽  
Observation Angle ◽  
Initial Angle ◽  
Mass Spectrometers ◽  
Small Uncertainty ◽  
Ion Kinetic Energy ◽  
Double Focusing ◽  
Selection Of

Experimental problems associated with studies of the scattering of kilovolt projectile ions in mass spectrometers designed primarily for chemical analysis are discussed. The parameters that are important in satisfactorily controlling and defining the actual scattering angle in relation to the observation angle are considered in detail. Two different experimental configurations are considered; angular selection before, or after kinetic energy analysis of the collision products. A modification to a VG ZAB-2F double-focusing mass spectrometer, in order to observe angle-resolved ion kinetic energy spectra of collisionally scattered ion beams, is described. Initial angle-resolved experiments on systems that do not involve fragmentation, have been performed. The results are presented for the angle-resolved energy loss spectra of Ar + and N 2 + and the angle-resolved charge-stripping of Ar + . A feature of the apparatus described is the small uncertainty in the angular selection of the analysing angle-resolved slit.

Laser photodissociation of the isotopic hydrogen molecular ions. Comparison between experimental and ab initio computed fragment kinetic energy spectra

1976 ◽  
Vol 16 (1) ◽  
pp. 75-80 ◽  
Author(s):  
J.-B. Ozenne ◽  
J. Durup ◽  
R.W. Odom ◽  
C. Pernot ◽  
A. Tabché-Fouhaillé ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Ab Initio ◽  
Molecular Ions ◽  
Energy Spectra ◽  
Isotopic Hydrogen ◽  
Fragment Kinetic Energy
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