Mass Spectrometry of Some Substituted 2-Benzylidenecyclohexanones and 2,6-bis-Benzylidenecyclohexanones

1973 ◽  
Vol 51 (9) ◽  
pp. 1458-1470 ◽  
Author(s):  
P. J. Smith ◽  
J. R. Dimmock ◽  
W. A. Turner
Keyword(s):  
Mass Spectrometry ◽  
Carbon Monoxide ◽  
Substitution Reaction ◽  
Mass Spectra ◽  
Aromatic Substitution ◽  
Fragmentation Pathways ◽  
Ortho Substituent

The mass spectra of a series of some substituted 2-benzylidenecyclohexanones and a series of substituted 2,6-bis-benzylidenecyclohexanones have been determined at 70 eV. The major fragmentation pathways include an intramolecular aromatic substitution reaction leading to the loss of an ortho-substituent with the formation of a stable benzopyrylium ion, loss of carbon monoxide and ethylene from the parent ion and also further ions derived from subsequent cleavages of the cyclohexanone ring. The structural and electronic factors involved in the aromatic substitution reaction were examined by comparing the M – H/M and M – Cl/M ratios determined from the spectra of the various substrates.

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.

Studies on the mass spectrometry of some acyclic nuclear substituted styryl ketoximes and ketones with special reference to the ortho effect

1979 ◽  
Vol 57 (22) ◽  
pp. 2908-2915 ◽  
Author(s):  
C. B. Nyathi ◽  
J. R. Dimmock ◽  
L. M. Smith
Keyword(s):  
Mass Spectrometry ◽  
Special Reference ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Fragmentation Pathways ◽  
Total Absence ◽  
Cyclization Process ◽  
Steric Factors ◽  
Acyclic Ketones ◽  
Ortho Substituent

The mass spectra of several ring substituted acyclic styryl ketoximes and analogous ketones have been determined at 70 eV and also at low ionization voltages. The major fragmentation pathways for the oximes are loss of the ortho substituent from the parent ion as well as loss of the hydroxyl and hydroxylamine radicals. Other fragmentation pathways include γ- and δ-cleavages as well as the McLafferty rearrangement. While there was a total absence of α-cleavage from the parent ions, the facility of loss of the ortho substituents from the oxime molecular ions was compared with the same process occurring in the corresponding acyclic ketones, as well as the related cyclic derivatives, namely the substituted 2-benzylidinecyclohexanones and oximes. Stabilization of the resultant cyclized ion as well as steric factors are considered as factors favouring the cyclization process.

Mass Spectrometry of Some Substituted 2-Benzylidenecyclohexanone Oximes

1973 ◽  
Vol 51 (9) ◽  
pp. 1471-1475 ◽  
Author(s):  
P. J. Smith ◽  
J. R. Dimmock ◽  
W. A. Turner
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectrum ◽  
Hydroxyl Radical ◽  
Mass Spectra ◽  
Similar Process ◽  
Fragmentation Pathways ◽  
Ortho Substituent

The mass spectra of several substituted 2-benzylidenecyclohexanone oximes have been determined at 70 eV and at lower ionization voltages. The major fragmentation pathways for the oximes are loss of the ortho substituent from the parent ion as well as loss of hydroxyl radical. The facility of loss of the ortho substituent is compared with a similar process involved in the fragmentation of substituted 2-benzylidenecyclohexanones. In addition, the mass spectrum of the acetate of 2-benzylidenecyclohexanone oxime was determined and showed a M – 1 peak and also a peak corresponding to the parent oxime formed by loss of ketene.

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.

Mechanism and structure in chemical ionization mass spectrometry: tricyclic flavanoid compounds

1973 ◽  
Vol 26 (7) ◽  
pp. 1577 ◽  
Author(s):  
JW Clark-Lewis ◽  
CN Harwood ◽  
MJ Lacey ◽  
JS Shannon
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Chemical Ionization ◽  
Ionization Mass Spectrometry ◽  
Chemical Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Fragmentation Pathways ◽  
Fragment Ions ◽  
Metastable Ions ◽  
Fragmentation Patterns

The chemical ionization mass spectra of a series of tricyclic flavanoid compounds have been examined using isobutane and hydrogen as reagent gases and the fragmen- tation modes have been correlated systematically in terms of structure. The technique produces simple fragmentation patterns and abundant metastable ions. The use of deuterium as reagent gas reveals the influence of extraneous water on the spectra and facilitates the interpretation of the fragmentation pathways. The fragment ions appear to arise from isomeric progenitors protonated at different sites in the molecules.

scholarly journals Elucidation of the Mass Fragmentation Pathways of Tomatidine and β1-Hydroxytomatine using Orbitrap Mass Spectrometry

2015 ◽  
Vol 10 (4) ◽  
pp. 1934578X1501000 ◽  
Author(s):  
Giovanni Caprioli ◽  
Michael Cahill ◽  
Serena Logrippo ◽  
Kevin James
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Ion Trap ◽  
Biological Effects ◽  
Biologically Active ◽  
Fragmentation Pathways ◽  
Multi Stage ◽  
Orbitrap Mass Spectrometry ◽  
Characteristic Fragmentation ◽  
Collisional Induced Dissociation

Tomatoes, members of the Solanaceae plant family, produce biologically active secondary metabolites, including glycoalkaloids, which may have both adverse and beneficial biological effects. Using the linear ion trap (LIT) mass spectrometry, multi-stage collision induced dissociation (CID) experiments (MSn) were performed to elucidate characteristic fragmentation pathways of the glycoalkaloid, tomatidine and of β1-hydroxytomatine. High resolution with high accuracy mass analysis using an Orbitrap fourier transform MS with higher-energy collisional induced dissociation (HCD) was used to produce mass spectra data across a wide spectral range for confirmation of proposed ion structures and formulae.

scholarly journals Mass Spectrometry of Bis-Quinolizidine Alkaloids: FAB-MS of Oxo-Substituted Sparteines

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Beata Jasiewicz ◽  
Elżbieta Wyrzykiewicz
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Collision Induced Dissociation ◽  
Quinolizidine Alkaloids ◽  
Positional Isomers ◽  
Mass Spectral Fragmentation ◽  
Fragmentation Pathways ◽  
Mass Spectral

The unpublished in the literature FAB mass spectral fragmentation of seven oxosparteines (i.e., 2-oxosparteine, 15-oxosparteine, 17-oxosparteine, 2,17-dioxosparteine, 2,13-dioxosparteine, 2-oxo-13-hydroxysparteine, and 2-oxo-17-hydroxysparteine) is investigated. Fragmentation pathways, elucidation of which was assisted by FAB/collision-induced dissociation (CID) mass spectra measurements, are discussed. The data obtained create the basis for distinguishing positional isomers.

The Mass Spectrometry of para-Substituted Benzyl Nitrates

1971 ◽  
Vol 49 (2) ◽  
pp. 333-337 ◽  
Author(s):  
P. J. Smith
Keyword(s):  
Mass Spectrometry ◽  
Isotope Effect ◽  
Mass Spectra ◽  
Deuterium Isotope Effect ◽  
Deuterium Labelling ◽  
Fragmentation Pathways ◽  
Hydrogen Deuterium

The mass spectra of several para-substituted benzyl nitrates have been measured at 70 and 15 eV. The major fragmentation pathways have been established using deuterium labelling and measurement of metastable peaks. The formation of the para. Y.C6H4.CH2O+ ions from the parent ions approximately correlate with the Hammett sigma constants. A hydrogen-deuterium isotope effect of approximately 1.8 was found for the loss of hydrogen (deuterium) from the C6H6CHDO+ ion at 10 eV.

scholarly journals ESI-MSnstudy on the fragmentation of protonated cyclic-dipeptides

2009 ◽  
Vol 23 (3-4) ◽  
pp. 131-139 ◽  
Author(s):  
Yan-Chun Guo ◽  
Shu-Xia Cao ◽  
Xiang-Kun Zong ◽  
Xin-Cheng Liao ◽  
Yu-Fen Zhao
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
High Resolution Mass Spectrometry ◽  
Biological Activities ◽  
Fragmentation Pathway ◽  
Amino Acid Residues ◽  
Cyclic Dipeptides ◽  
Fragmentation Pathways ◽  
Potential Applications ◽  
Characteristic Fragment

Cyclic dipeptides are relatively simple compounds that can exhibit a great variety of important biological activities. The fragmentation pathways of protonated cyclic dipeptides have been studied by electrospray ionization multistage mass spectrometry (ESI-MSn). The mass spectra studies of the cyclic dipeptides showed that the cyclic dipeptides with the similar substituents, the side chains of amino acid residues at the diketopiperazine ring, followed the same fragmentation pathway. In the fragmentation spectra of protonated cyclic dipeptides, some characteristic fragment ions were observed and could be used to distinguish the cyclic dipeptides. The hydrogen/deuterium (H/D) exchange experiment and the high-resolution mass spectrometry (Q-TOF) were used to verify and rationalize the proposed fragmentation pathways. These observations may have some potential applications in the structural elucidation and interpretation of the mass spectra of homologous compounds.

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