Structure and fragmentation of C5H11O+ ions formed by chemical ionization

1985 ◽  
Vol 63 (3) ◽  
pp. 609-618 ◽  
Author(s):  
John V. Headley ◽  
Alex. G. Harrison
Keyword(s):  
Proton Transfer ◽  
Mass Spectra ◽  
Chemical Ionization ◽  
Collision Induced Dissociation ◽  
Ionization Mass ◽  
Fragmentation Reaction ◽  
Isotopic Labelling ◽  
Precursor Structure ◽  
Reaction Channels

The proton transfer chemical ionization mass spectra of eleven C5H10O isomers have been obtained using H3+, N2H+, HCO+, and D3+ as reagent ions. The chemical ionization mass spectra in combination with isotopic labelling and metastable ion studies have made it possible to elucidate the major fragmentation reaction channels of the C5H11O+ ions formed and their dependence on precursor structure. From collision induced dissociation studies nine stable distinct C5H11O+ ion structures have been identified; protonated 3-methylbutanone and protonated 2,2-dimethylpropanal readily interconvert by a pinacolic – retro-pinacolic rearrangement.

Effect of reaction exothermicity on the proton transfer chemical ionization mass spectra of isomeric C5 and C6 alkanols

1981 ◽  
Vol 59 (14) ◽  
pp. 2125-2132 ◽  
Author(s):  
Jan A. Herman ◽  
Alex. G. Harrison
Keyword(s):  
Mass Spectra ◽  
Chemical Ionization ◽  
Energy Partitioning ◽  
Ionization Mass ◽  
Fragmentation Reaction ◽  
Secondary Alcohols ◽  
Primary Alcohols ◽  
Tertiary Alcohols ◽  
Protonation Reaction ◽  
Alkane Elimination

The chemical ionization mass spectra of eight C5 alkanols and fourteen C6 alkanols have been obtained using H3+, N2H+, CO2H+, N2OH+, and HCO+ as reactant ions. This choice of reactant ions allows the exothermicity of the protonation reaction to be varied from ∼90 kcal mol−1 (H3+) to ∼50 kcal mol−1 (HCO+). The major fragmentation reaction in all cases was H2O elimination from the protonated alcohol forming the appropriate C5H11+ or C6H13+ alkyl ion. The extent of further fragmentation of the alkyl ions decreased with decreasing exothermicity of the protonation reaction and was greatest for alkyl ions derived from primary alcohols, less for alkyl ions derived from secondary alcohols, and very small for alkyl ions derived from tertiary alcohols. The results indicate that there is negligible rearrangement to more stable alkyl ions prior to attaining the critical configuration which determines the energy partitioning between R+ and H2O in the fragmentation of ROH2+. Other less important reaction modes in the CI spectra involved formation of (M – H)+ ions and formation of oxycarbonium ions by alkane elimination from protonated alcohols.

scholarly journals Discrimination of structural isomers of amphetamine using carbon dioxide negative-ion chemical ionization mass spectrometry

1997 ◽  
Vol 13 (2) ◽  
pp. 151-161 ◽  
Author(s):  
Kevin B. Thurbide ◽  
C. M. Elson ◽  
P. G. Sim
Keyword(s):  
Carbon Dioxide ◽  
Mass Spectra ◽  
Chemical Ionization ◽  
Negative Ion ◽  
Ionization Mass ◽  
Structural Isomers ◽  
Mass Spectral ◽  
Negative Ion Chemical Ionization ◽  
Spectral Behaviour ◽  
Carbon Dioxide Plasma

The negative‒ion chemical ionization mass spectra of a group of structural isomers of amphetamine have been studied using carbon dioxide as the reagent gas. Characteristic and reproducible differences are observed for each member of the set implying that this technique offers a means of distinguishing among groups of amphetamine isomers. Characteristic adducts to the molecular ion are observed in the form (M–[H]+[O]) and (M–[H]+[CO2]). Descriptions of some fragments are given based on the mass spectral behaviour of a set of analogue compounds and the results of oxygen-18 labelled carbon dioxide reagent gas experiments. Contents of the carbon dioxide plasma and their impact on various analytes is also discussed.

The monomeric metaphosphate anion in negative-ion chemical-ionization mass spectra of phosphotriesters

1984 ◽  
Vol 106 (23) ◽  
pp. 6877-6883 ◽  
Author(s):  
Seymour Meyerson ◽  
Donald J. Harvan ◽  
J. Ronald Hass ◽  
Fausto Ramirez ◽  
James F. Marecek
Keyword(s):  
Mass Spectra ◽  
Chemical Ionization ◽  
Negative Ion ◽  
Ionization Mass ◽  
Negative Ion Chemical Ionization

Negative chemical ionization mass spectra of polycyclic chlorinated insecticides

1972 ◽  
Vol 6 (11) ◽  
pp. 1171-1181 ◽  
Author(s):  
Ralph C. Dougherty ◽  
John Dalton ◽  
Francis J. Biros
Keyword(s):  
Mass Spectra ◽  
Chemical Ionization ◽  
Ionization Mass ◽  
Negative Chemical Ionization

Isobutane chemical ionization mass spectra of lanthanide perfluorinated .beta.-diketonates

1974 ◽  
Vol 46 (6) ◽  
pp. 726-728 ◽  
Author(s):  
T. H. Risby ◽  
P. C. Jurs ◽  
F. W. Lampe ◽  
A. I. Yergey
Keyword(s):  
Mass Spectra ◽  
Chemical Ionization ◽  
Ionization Mass

Chemical ionization mass spectra of mononitroarenes

1980 ◽  
Vol 15 (6) ◽  
pp. 284-288 ◽  
Author(s):  
Alex. G. Harrison ◽  
R. Krishna Mohan Rao Kallury
Keyword(s):  
Mass Spectra ◽  
Chemical Ionization ◽  
Ionization Mass
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