Mass spectra of ar-nitrostyrenes

1974 ◽  
Vol 27 (12) ◽  
pp. 2583 ◽  
Author(s):  
S Middleton ◽  
M Butcher ◽  
RJ Mathews
Keyword(s):  
Mass Spectra ◽  
Fragmentation Pathways ◽  
Ortho Isomer

The mass spectra of m- and p-nitrostyrene are relatively simple but that of the ortho isomer is quite complicated due to the intervention of numerous fragmentation pathways which involve interaction between the nitro and vinyl groups.

Differentiation of the Isomeric o-(m- and p-) Nitro-(Chloro- and Bromo-)Benzyl-2,4-(and 2,1-) Disubstituted 2-Thiocytosinium Halides by Electron Impact Ionisation and Fast Atom Bombardment Mass Spectrometry

2009 ◽  
Vol 15 (4) ◽  
pp. 497-506 ◽  
Author(s):  
Tomasz Pospieszny ◽  
Elżbieta Wyrzykiewicz
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Fast Atom Bombardment ◽  
Collision Induced Dissociation ◽  
Mass Measurements ◽  
Fragmentation Pathways ◽  
Mass Spectral ◽  
Fragment Ions ◽  
Accurate Mass Measurements ◽  
Impact Ionisation

Electron ionisation (EI) and fast atom bombardment (FAB) mass spectral fragmentations of nine 2,4-(and 2,1-) disubstituted o-( m- and p-)nitro-(chloro- and bromo-)-2-thiocytosinium halides are investigated. Fragmentation pathways, whose elucidation is assisted by accurate mass measurements and metastable transitions [EI-mass spectrometry (MS)], as well as FAB/collision-induced dissociation (CID) mass spectra measurements are discussed. The correlations between the abundances of the (C11H10N4SO2)+1–3; (C11H10N3SCl)+4–6 and (C11H10N3SBr)+7–9 ions and the selected fragment ions (EI-MS), as well as (C18H16N5SO4)+1–3; (C18H16N3SCl2)+4–6 and (C18H16N3SBr2) + 7–9 ions and the selected ions (C7H6NO2)+1–3; (C7H6Cl)+ 4–6; (C7H6Br)+ 7–9 (FAB-MS) are discussed. The data obtained can be used for distinguishing isomers.

Fragmentation pathways in the mass spectra of isomeric phenylazoxypyridine-N-oxides

1992 ◽  
Vol 70 (4) ◽  
pp. 1028-1032 ◽  
Author(s):  
Nigel J. Bunce ◽  
H. Stewart McKinnon ◽  
Randy J. Schnurr ◽  
Sam R. Keum ◽  
Erwin Buncel
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Electron Impact ◽  
Mass Spectra ◽  
Chemical Reduction ◽  
Ion Source ◽  
Tandem Mass ◽  
Mass Spectral Fragmentation ◽  
Fragmentation Pathways ◽  
Mass Spectral

The mass spectral fragmentation pathways of a series of phenylazoxypyridine-N-oxides have been studied under electron impact conditions using tandem mass spectrometry. Besides simple C—N cleavages, the azoxypyridine-N-oxides undergo deep-seated rearrangements directly from the molecular ion. In addition, the spectra are complicated by a purely chemical reduction of the N—O functionalities that occurs in the ion source prior to ionization.

scholarly journals Fragmentation pathways of drugs of abuse and their metabolites based on QTOF MS/MS and MSE accurate-mass spectra

2011 ◽  
Vol 46 (9) ◽  
pp. 865-875 ◽  
Author(s):  
Lubertus Bijlsma ◽  
Juan V. Sancho ◽  
Félix Hernández ◽  
Wilfried M.A. Niessen
Keyword(s):  
Mass Spectra ◽  
Drugs Of Abuse ◽  
Accurate Mass ◽  
Fragmentation Pathways

Mass Spectrometry of some Nuclear Substituted Styryl Ketones

1972 ◽  
Vol 50 (6) ◽  
pp. 871-879 ◽  
Author(s):  
P. J. Smith ◽  
J. R. Dimmock ◽  
W. G. Taylor
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Aromatic Substitution ◽  
Fragmentation Pathways ◽  
Fragment Ions ◽  
Aliphatic Ketones ◽  
Decomposition Processes ◽  
Structure Formula ◽  
Related Compounds ◽  
Carbonyl Function

The mass spectra of a series of nuclear substituted styryl ketones with the structure[Formula: see text]and several relaTed compounds have been determined. The major fragmentation pathways include such processes as an aromatic substitution reaction occurring in the molecular ion as well as the McLafferty rearrangement. Only one of the two possible α-cleavages at the carbonyl function was observed. The major decomposition processes are outlined and compared with the recent results of a study on α,β-unsaturated aliphatic ketones. Mechanistic pathways are suggested for the formation of the major fragment ions.

The mass spectra of pyrimidines. II. 2(1H)-Pyrimidinethiones and some N(1)-substituted derivatives

1984 ◽  
Vol 62 (11) ◽  
pp. 2340-2343 ◽  
Author(s):  
Robin T. B. Rye ◽  
Oswald S. Tee ◽  
Eva M. Kazdan
Keyword(s):  
Kinetic Energy ◽  
Energy Release ◽  
Mass Spectra ◽  
Kinetic Energy Release ◽  
Exact Mass ◽  
Metastable Peak ◽  
Fragmentation Pathways

The EI induced fragmentation of 2(1H)-pyrimidinethione (1), some N(1)-substituted derivatives, and 2(1H)-pyrimidineselenone (4) have been studied. Principal fragmentation pathways have been identified using 2H-labelling, metastable defocussing, and exact mass measurements.The fragmentations of 1 and 4 generally parallel those reported for 2(1H)-pyrimidinone. In contrast to the oxo-compound, however, direct expulsion of the exocyclic hetero atom is significant in the fragmentation of 1, and dominates the spectrum of 4.Based on metastable peak abundances and kinetic energy release measurements, it is postulated that the [M – H]+ entity generated from N-ethyl-2-pyrimidinethione has a thiazolinium structure.

Mass spectral studies of some desaurins and related 3,5-bismethylene-1,2,4-trithiolanes

1968 ◽  
Vol 46 (3) ◽  
pp. 365-375 ◽  
Author(s):  
Peter Yates ◽  
Thomas R. Lynch ◽  
L. S. Weiler
Keyword(s):  
Carbonyl Group ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Spectral Studies ◽  
Mass Measurements ◽  
Metastable Peak ◽  
Fragmentation Pathways ◽  
Mass Spectral ◽  
Accurate Mass Measurements ◽  
Doubly Charged

The mass spectra of three desaurins and four related 3,5-bismethylene-1,2,4-trithiolanes have been interpreted with the aid of metastable peak assignments and accurate mass measurements. Strong molecular ion peaks are observed in the case of the aryl desaurins but not in that of their trithiolane counterparts. A variety of fragmentation pathways are postulated for the molecular ions, including cleavage on either side of a carbonyl group and elimination of a molecule of acylthioketene. In the case of the desaurins the latter process results in the formation of acylthioketene molecular ions, which could be distinguished from the doubly charged desaurin molecular ions. In the case of two of the trithiolanes, it is proposed that the ions resulting from loss of acylthioketene from the molecular ions undergo a novel type of McLafferty rearrangement and loss of carbon suboxysulfide to give aryl mercaptan molecular ions.

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.

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