The Behavior of 1-Phenyl-2-benzimidazolinethione and 1-Phenyl-2-benzimidazolinone upon Electron Impact and Pyrolysis

1974 ◽  
Vol 52 (13) ◽  
pp. 2359-2366 ◽  
Author(s):  
Denis C. K. Lin ◽  
Michael L. Thomson ◽  
Don C. DeJongh
Keyword(s):  
Mass Spectrum ◽  
Electron Impact ◽  
Mass Spectra ◽  
Path Loss ◽  
Starting Material ◽  
Base Peak ◽  
Pyrolysis Products

The mass spectra of 1-phenyl-2-benzimidazolinethione (3) and 1-phenyl-2-benzimidazolinone (4) have been compared with their pyrolysis products and similarities have been found. In the 70 eV mass spectrum of 3, the base peak results from the loss of H•; at low ionizing voltages, this path and a competing path, loss of S, are the only ones which remain. At 650° in a stream of N2, 1-phenylbenzimidazole (8, 20%) formed from the loss of S and benzimidazo-[2,1-b]benzothiazole (5, 11%) formed by loss of H2. The major fragmentation paths in the mass spectrum of 4 are loss of CHO• and NCO•. At 950°, phenazine (6, 35%) formed by loss of CH2O, and carbazole (7, 14%) formed by loss of HNCO. In each pyrolysis, 65–70% of the starting material was recovered or accounted for.

N-Benzylidene-2-nitrobenzenesulfenamide and 1-Nitro-2-(phenylthio)benzene: Comparison of Their Behavior on Flash Vacuum Pyrolysis and Under Electron Impact

1990 ◽  
Vol 43 (10) ◽  
pp. 1779 ◽  
Author(s):  
RG Gillis ◽  
QN Porter ◽  
LL Yeoh
Keyword(s):  
Mass Spectrum ◽  
Electron Impact ◽  
Preparative Thin Layer Chromatography ◽  
Gas Chromatography Mass Spectrometry ◽  
Base Peak ◽  
Pyrolysis Products ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Electron Impact Mass ◽  
Layer Chromatography

The molecular ion of N-benzylidene-2-nitrobenzenesulfenamide (1) loses SO2 and N2 and gives a base peak at m/z 165, C13H9, and another abundant peak at m/z 166, C13H10. Analysis, by gas chromatography/mass spectrometry and by preparative thin-layer chromatography, of the products of flash vacuum pyrolysis at 500-800°C of (1) showed no detectable hydrocarbon, but dibenzothiophen (mol. wt 184) was isolated and identified. The abundance of m/z 184 in the positive-ion mass spectrum of (1) is about 1%. In the mass spectrum of 1-nitro-2-( phenylthio )benzene (2a) the base peak is at m/z 167, C12H9N, and there is a fragment ion at m/z 184, C12H8S (35%). However, carbazole (3) could not be isolated from the flash vacuum pyrolysis products, but dibenzothiophen (4) was obtained in increasing yield as the pyrolysis temperature was raised from 500 to 800°C. It is clear from these results that drawing analogies between electron impact mass spectra and flash vacuum pyrolysis results is somewhat hazardous.

Pyrolyses and Mass Spectra of 2-Benzoxazolinone, 2-Benzimidazolinone, and 2-Benzothiazolinone

1973 ◽  
Vol 51 (20) ◽  
pp. 3313-3321 ◽  
Author(s):  
Michael L. Thomson ◽  
Don C. DeJongh
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Chemical Ionization ◽  
Starting Material ◽  
Ionization Mass ◽  
Isolation And Identification ◽  
Pyrolysis Products

The electron-impact and chemical-ionization mass spectra of 2-benzoxazolinone (5), 2-benzimidazolinone (6), and 2-benzothiazolinone (7) have been compared with their pyrolysis products and parallels have been found. In each case, loss of CO occurs from [Formula: see text] followed by loss of CO for 5 and by HCN for 6 and 7. At 950° in a stream of N2, 5 gave 17% of C5H5N isomers, related to the loss of 2CO, along with 5.6% of quinoline. Compound 6 gave 14% of C6H4N2 isomers, related to the loss of CO. At 950°, 7 gave 2-thiophenecarbonitrile (1.1%), cyanonaphthalenes (4.5%), aniline (3%), cyanobenzene (2.5%), naphthalene (1.5%), and phenylisocyanate (2.5%). From 5–720–70% of the starting material was recovered or accounted for by isolation and identification of products in each case. G.c./m.s. was used to study pyrolysis mixtures.

The isolation of 11-oxotetrahydrorhombifoline from Ormosia coutinhoi and a study of its mass spectrum

1967 ◽  
Vol 45 (7) ◽  
pp. 751-757 ◽  
Author(s):  
Stewart McLean ◽  
A. G. Harrison ◽  
D. G. Murray
Keyword(s):  
Mass Spectrum ◽  
Electron Impact ◽  
Mass Spectra ◽  
Equilibrium Theory ◽  
Side Chain ◽  
Fragmentation Reaction ◽  
Quasi Equilibrium ◽  
Molecular Ion ◽  
Dihydro Derivative ◽  
A Minor

11-Oxotetrahydrorhombifoline (I) has been isolated from the alkaloidal extract of the bark of Ormosia coutinhoi, and its dihydro derivative II has been prepared. An examination of the mass spectra of these compounds and of their 3,3-d2 derivatives has led to the elucidation of the course of the major electron impact induced fragmentations undergone by the molecules. The main fragmentation of I leads to loss of C3H5 from the side chain to form an ion of m/e 221, with a minor path involving a central fission of the molecular ion to form an ion of m/e 150. The mass spectrum of II shows that the loss of C3H7 to form the ion of m/e 221 is a minor process, the main fragmentation reaction involving a central fission to form an ion of m/e 152 analogous to the ion of m/e 150 from I. This change in the spectrum is shown to be consistent with predictions based on the quasi-equilibrium theory of mass spectra.

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.

Spectres de masse d'hydrazino-2 benzo- et naphtothiazoles et d'hydrazones des méthyl-3 benzo- et naphtothiazolinones-2

1975 ◽  
Vol 53 (23) ◽  
pp. 3677-3680 ◽  
Author(s):  
Jean-Claude Richer ◽  
Philippe Lapointe ◽  
Martine Beljean ◽  
Michel Pays
Keyword(s):  
Mass Spectrum ◽  
Mass Spectra ◽  
Base Peak ◽  
Molecular Ion ◽  
Ion Fragmentation ◽  
Fragment Ions ◽  
Sampling Probe ◽  
Electron Impact Mass ◽  
Impact Mass ◽  
Hydrazone Form

Electron impact mass spectra are reported for the hydrazones of 3-methyl-2-benzothiazolinone (1), of 4-, 5-, 6-, and 7-chloro-3-methylbenzo-2-thiazolinones (2, 3, 4, and 5) and of 3-methyl-naphtho[2,1-d]-2-thiazolinone (6), as well as for 2-hydrazinobenzothiazole (7), for 4-, 5-, 6-, and 7-chloro-2-hydrazinobenzothiazoles (8, 9, 10, and 11) and for 2-hydrazinonaphtho[2,1-d]thiazole (12). The results obtained in the two series are compared. The 2-hydrazone and 3-methyl-benzo-2-thiazolinone and its derivatives all form a base peak corresponding to the molecular ion; fragmentation proceeds mainly by successive losses of·NH2, HCN, HCN, and then CS. Initial losses of N2H2, NH·, and NH3 are minor fragmentation routes.In the case of 2-hydrazinobenzothiazole and its derivatives, the base peak is still that of the molecular ion; however, the relative proportions of the various fragment ions vary with the position of sampling probe inside the apparatus. Thus it is concluded that the observed mass spectrum is that of a mixture of the possible hydrazone-hydrazine tautomers. The principal fragmentations involve the initial loss of NH3 (leading to a stabilized ion), of NH2· (probably from the hydrazone form), and of N2H2.(Journal Translation)

Mass spectra of 4,4-dimethyl-A-homocholestane-3,5- and 3,4a diols and their derivatives

1982 ◽  
Vol 47 (12) ◽  
pp. 3328-3338
Author(s):  
Antonín Trka ◽  
Helena Velgová
Keyword(s):  
Mass Spectrum ◽  
Electron Impact ◽  
Mass Spectra ◽  
Neutral Fragment ◽  
Molecular Ion ◽  
Impact Fragmentation ◽  
Fragmentation Processes

Partial mass spectra of the following 4,4-dimethyl-A-homocholestane derivatives are given: 3,5-epoxides I and II, 3,5-diols III-VI, 3-methoxy-5-ols VII-IX, 3-acetoxy-5-ol X, 3,4a-diols XI-XIV, 3-acetoxy-4a-ols XV-XVIII and 4,4-[2H6]-dimethyl-3,4a-diol XIX, and their electron impact fragmentation investigated. The mass spectra of epoxides I and II, diols III-VI and acetate X are very similar. Considerable differences in mass spectra of methoxy derivatives VII-IX are explained by two mechanisms of elimination of CH3OH from M+. The same similarity of the fragmentation processes and the mass spectra is also observed in diols XI-XIV and acetates XV-XVIII. For the formation of the characteristic ion m/z 288 a fragmentation scheme containing an usual cleavage of the rings A, B, and C is proposed. On the basis of comparison with the mass spectrum of the 4,4-[2H6]dimethyl analogue XIX it was shown that the ion m/z 361 in the mass spectra of diols XI-XIV is formed by elimination of the neutral fragment C6H13 from A-ring of the molecular ion, the last process being accompanied by the 3-hydroxyl transfer from A-ring to the rest of the molecular ion.

The Fragment Ion C13H9O2 m/z 197 in the Mass Spectra of 2-(2′-R-phenyl)benzoic Acids

1990 ◽  
Vol 43 (1) ◽  
pp. 203 ◽  
Author(s):  
RG Gillis ◽  
QN Porter
Keyword(s):  
Mass Spectrum ◽  
Electron Impact ◽  
Mass Spectra ◽  
Chemical Ionization ◽  
Electron Impact Mass Spectrum ◽  
Benzoic Acids ◽  
Ipso Substitution ◽  
Methane Chemical Ionization ◽  
Electron Impact Mass ◽  
Impact Mass

In the electron impact mass spectrum of 2-(2°-R-phenyl)benzoic acids where R=H, NO2, OCH3, COOH, or Br, an abundant fragment ion m/z 197 is formed by an ipso substitution in which R is expelled as a radical. The structure of the ion m/z 197 has been shown by collision-activated dissociation to be identical with that of the protonated molecule formed by methane chemical ionization of 6H-dibenzo[ b,d ]pyran-6-one.

Oxygen equilibration in the mass spectra of 2-benzoylbenzoic acid

1976 ◽  
Vol 29 (2) ◽  
pp. 301
Author(s):  
MJ Lacey ◽  
JS Shannon
Keyword(s):  
Mass Spectrum ◽  
Benzoic Acid ◽  
Electron Impact ◽  
Mass Spectra ◽  
Chemical Ionization ◽  
Molecular Ions ◽  
Electron Impact Mass Spectrum ◽  
Primary Fragmentation ◽  
Electron Impact Mass ◽  
Impact Mass

Positional integrity of the label is maintained in the molecular ions of 2-ben~oyl[18O]benzoic acid prior to a number of primary fragmentation modes. Positional integrity is also evident for some source and metastable reactions of the protonated molecular ions formed in its chemical ionization (H2) mass spectrum. The (M-Ph)+ ions formed in the electron impact mass spectrum, however, fragment further after complete equilibration of their oxygen atoms.

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