ChemInform Abstract: Characterization of Cyanogen N-Oxide Radical Cation (NCCNO.+) in the Gas Phase by Tandem Mass Spectrometry Methodologies and ab initio Calculations.

ChemInform ◽  
2010 ◽  
Vol 29 (11) ◽  
pp. no-no
Author(s):  
R. FLAMMANG ◽  
M. BARBIEUX-FLAMMANG ◽  
P. GERBAUX ◽  
C. WENTRUP ◽  
M. W. WONG
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Gas Phase ◽  
Radical Cation ◽  
Tandem Mass ◽  
Abstract Characterization

Characterization of New Cumulenes C2NX2(X = O or S):  Tandem Mass Spectrometry and ab Initio Studies

1996 ◽  
Vol 100 (25) ◽  
pp. 10536-10541 ◽  
Author(s):  
Ming Wah Wong ◽  
Curt Wentrup ◽  
Eva H. Mørkved ◽  
Robert Flammang
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Ab Initio ◽  
Tandem Mass

The decarbonylation of ionized β-hydroxypyruvic acid: the hydrogen-bridged radical cation [CH2=O . . .H . . .==C-OH].+ studied by experiment and theory

1998 ◽  
Vol 76 (3) ◽  
pp. 335-349 ◽  
Author(s):  
Lorne M Fell ◽  
Peter C Burgers ◽  
Paul JA Ruttink ◽  
Johan K Terlouw
Keyword(s):  
Mass Spectrometry ◽  
Methyl Ester ◽  
Tandem Mass Spectrometry ◽  
Ab Initio ◽  
Radical Cation ◽  
Glycolic Acid ◽  
High Energy ◽  
Low Energy ◽  
Tandem Mass ◽  
Low Energy Ions

The intriguing gas-phase ion chemistry of β-hydroxypyruvic acid (HPA), HOCH2C(==O)COOH, has been investigated using tandem mass spectrometry (metastable ion (MI) and (multiple) collision-induced dissociation (CID) experiments, neutralization-reionization mass spectrometry (NRMS), 18O and D isotopic labelling on both the acid and its methyl ester) in conjunction with computational chemistry (ab initio MO and density functional theories). HPA does not enolize upon evaporation, but it retains its keto structure. When ionized, decarbonylation occurs and, depending on the internal-energy content, this dissociation reaction proceeds via two distinct routes. The source-generated, high-energy ions lose the keto C==O, not via a least-motion extrusion into ionized glycolic acid, HOCH2COOH.+ , but via a rearrangement that yields the title H-bridged radical cation CH2==O ... H ... O==C-OH.+ for which Δ Hf0 = 99 ± 3 kcal/mol. The long-lived low-energy ions enolize prior to decarbonylation and lose the carboxyl C==O. Again, this is not a least-motion extrusion (which would produce the most stable isomer, HOC(H)==C(OH)2.+ Δ Hf0 = 73 kcal/mol) but a rearrangement yielding the ion-dipole complex HOC(H)C==C==O.+/H2O. The methyl ester of HPA behaves analogously, yielding CH2==O... H ...O==C-OCH3.+ and HOC(H)C==C==O.+ / CH3OH upon decarbonylation of the high- and low-energy ions, respectively. Decarboxylation into the ylidion CH2OH2.+ characterizes the dissociation chemistry of both the title H-bridged ion and its glycolic acid isomer HOCH2COOH.+ . A computational analysis of this reaction (which satisfies the experimental observations) leads to the proposal that the decarboxylation of the acid occurs via CH2-O(H) ... H ... ==C==O.+ as the key intermediate, whereas the title H-bridged ion follows a higher energy route that involves ion-dipole rotations leading to the ionized carbene HO(H2)CO-C-OH.+ and the distonic ion H2O-C(H2)-O-C==O.+ as key intermediates.Key words: tandem mass spectrometry, hydrogen-bridged radical cation, hydroxypyruvic acid, ab initio calculations, keto-enol tautomerization, 18O labelling.

ChemInform Abstract: Characterization of Flavonoids by Tandem Mass Spectrometry and Metal Complexation Strategies

ChemInform ◽  
2008 ◽  
Vol 39 (19) ◽  
Author(s):  
Jennifer S. Brodbelt ◽  
Junmei Zhang ◽  
Michael Pikulski ◽  
Barry D. Davis ◽  
Basavaraj Girennavar ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Metal Complexation ◽  
Tandem Mass ◽  
Abstract Characterization

Gas-Phase Reactivity of Glycosides and Methyl Glycosides with Cu+, Ag+ and Pb2+ Ions by Fast-Atom Bombardment and Tandem Mass Spectrometry

2001 ◽  
Vol 7 (4-5) ◽  
pp. 321-330 ◽  
Author(s):  
Jean-Yves Salpin ◽  
Laurence Boutreau ◽  
Violette Haldys ◽  
Jeanine Tortajada
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Gas Phase ◽  
Fast Atom Bombardment ◽  
The Other ◽  
Tandem Mass ◽  
Pyranose Ring ◽  
Analytical Potential ◽  
Anomeric Center

The analytical potential of the complexation of three isomeric monosaccharides (D-glucose, D-galactose, D-fructose)and two methyl glycosides ( O-methyl-α-D-glucose and O-methyl-β-D-glucose)by three metal ions, Ag+, Cu+ and Pb2+, has been investigated by fast-atom bombardment (FAB)ionization and tandem mass spectrometry. Our results have shown that the unimolecular reactivity of Ag+ complexes allows the characterization of the C(4)stereochemistry of the pyranose ring, whereas a distinction between D-glucose and D-fructose is not achieved. On the other hand, each of the three [Cu + monosaccharide]+ complexes exhibits specific dissociation patterns. We have also observed that Pb2+ ions induce the richest reactivity and are of particular interest for the identification of the three isomers. Finally, this study has demonstrated that the stereochemistry of the anomeric center of O-methyl-D-glucose is easily determined by reaction with Ag+ or Pb2+ ions. Several mechanisms are proposed to account for the main fragmentations of cationized glucose.

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