Metastable Ion Studies. V. The Identification of C2H4O+ · Ion Structures from their Characteristic Kinetic Energy Releases

1975 ◽  
Vol 53 (14) ◽  
pp. 2076-2083 ◽  
Author(s):  
John L. Holmes ◽  
Johan K. Terlouw
Keyword(s):  
Kinetic Energy ◽  
Kinetic Energy Release ◽  
Ethyl Vinyl Ether ◽  
Ethyl Vinyl ◽  
Free Region ◽  
Unequivocal Identification ◽  
Field Free Region ◽  
Activation Data ◽  
Labelling Experiment ◽  
Good Energy

Metastable ion peaks for the fragmentation C2H4O+ • → C2H3O+ + H• have been studied in the first field-free region of a double focussing mass spectrometer under conditions of good energy resolution. Three isomeric C2H4O+ • ions were generated[Formula: see text] (b) CH3CHO+, and (c) CH2=CHOH+ • from ethylene oxide, acetaldehyde, and ethyl vinyl ether respectively, each fragment producing a different 1m* peak having a characteristic shape and kinetic energy release. The above ions do not therefore interconvert prior to fragmentation and their characteristic 1m* peaks permit their unequivocal identification, thus providing a powerful method for ion structure determination.In agreement with some recent collisional activation data it was found that the unbranched aldehydes, cyclic alcohols, and 2-haloethanols investigated generated (c) type C2H4O+ • ions. These are also produced by glycidol and α-furfuryl alcohol. Some compounds generated composite 1m* peaks, e.g. 1,3-dioxolane produces (a) and (c) ions, while compounds which produce prominent C2H5O+ ions having the protonated acetaldehyde structure, generate m/e 44 ions of structures (b) and (c). In isopropanol these components were separated by a deuterium labelling experiment. Contrary to earlier proposals, pyruvic acid does not generate (b) type ions but produces predominantly ions of structure (c).

scholarly journals Metastable ion studies. VI. The identification of C2H5N+• ion structures from their characteristic kinetic energy releases

1976 ◽  
Vol 54 (7) ◽  
pp. 1007-1014 ◽  
Author(s):  
John L. Holmes ◽  
Johan K. Terlouw
Keyword(s):  
Kinetic Energy ◽  
Energy Release ◽  
Kinetic Energy Release ◽  
Open Chain ◽  
Structural Identity ◽  
Free Region ◽  
Unequivocal Identification ◽  
Field Free Region ◽  
Labelling Experiment ◽  
Precursor Molecules

Metastable peaks for the fragmentation C2H5N+• → C2H4N+ + H• have been studied in the first field-free region of a double focussing mass spectrometer. Isomeric structures of C2H5N+• ions derived from a variety of precursor molecules were characterised by their metastable peak shape and kinetic energy release. The identifications were aided by appropriate deuterium labelling experiments. Four isomeric ionsr [Formula: see text]were shown to retain their structural identity within the ion energy and lifetime ranges observable in these experiments. Ion (a), generated from aziridine was found to be indistinguishable from its open chain isomer [Formula: see text]The results closely parallel those previously found for the isoelectronic C2H5N+• ions, but the differences in characteristic kinetic energy release are smaller. A simple deuterium exchange labelling experiment may be necessary for the unequivocal identification of C2H5N+• ion structures.

scholarly journals Kinetic Energy Release in Metastable Transitions. I

1967 ◽  
Vol 22 (1) ◽  
pp. 15-19 ◽  
Author(s):  
M. Barber ◽  
K. R. Jennings ◽  
R. Rhodes
Keyword(s):  
Kinetic Energy ◽  
Energy Release ◽  
Mass Spectrometer ◽  
Kinetic Energy Release ◽  
Peak Shape ◽  
Free Region ◽  
Field Free Region ◽  
Product Ions ◽  
Electrostatic Analyser

A method is described for detecting metastable transitions which take place with the release of kinetic energy in the field-free region between the source and electrostatic analyser of a doublefocusing mass spectrometer, and a procedure is given for evaluating the kinetic energy release. Values are given for a number of transitions and are in agreement with those obtained by other methods where comparison is possible. The variation of peak shape with accelerating voltage is ascribed to the varying efficiency with which product ions are collected.

An investigation of the structures of isomeric ions derived from acetone, diacetone alcohol, and mesityl oxide

1988 ◽  
Vol 66 (4) ◽  
pp. 591-597 ◽  
Author(s):  
Raymond Evans March ◽  
Alexander Baldwin Young
Keyword(s):  
Condensation Reaction ◽  
Small Variation ◽  
Kinetic Energy Release ◽  
High Energy ◽  
Mesityl Oxide ◽  
Ion Molecule Reactions ◽  
Diacetone Alcohol ◽  
Free Region ◽  
Hybrid Mass Spectrometer ◽  
Field Free Region

An investigation of the structures of isomeric ions formed in ion/molecule reactions occurring in 2-propanone (acetone), 4-hydroxy-4-mefhyl-2-pentanone (diacetone alcohol), and 4-methyl-3-penten-2-one (mesityl oxide) has been performed using a hybrid mass spectrometer of reversed geometry. Ions of m/z 117, which have been observed as products of ion/molecule reactions in acetone and in diacetone alcohol, may have a single structure if an aldol type condensation reaction occurs under acidic conditions in the gas phase; however, high energy collision induced dissociation (CID) results proved the two ions to be isomeric only.Dehydration of the m/z 117 ions produced a species of m/z 99 which, in the case of diacetone alcohol, may have the structure of protonated mesityl oxide. That the m/z 99 ion formed was unique to each system was demonstrated by high energy CID and kinetic energy release (KER) spectrometry. In the acetone system, CID results suggested that m/z 99 was an ion–dipole complex of [Formula: see text]; this hypothesis was tested by clustering [Formula: see text]with (CD3)2CO and comparison of its CID results with those obtained above. In the case of m/z 99 derived from diacetone alcohol or mesityl oxide, the neutral lost via metastable decomposition in the second field-free region was found to be C4H8, presumably 2-methyl propene. While the ion of m/z 99 may also eliminate methane to yield a species of m/z 83, the dominant metastable elimination from this ion is carbon monoxide rather than ethene as shown by collision induced dissociative ionization (CIDI). The ions of m/z 83 observed in the two systems exhibit very similar CID spectra; however, a small variation in the yield of products of m/z 41 and 43 suggests two structures for the ion derived from diacetone alcohol, one of which is identical to that seen in mesityl oxide.

The Ion Kinetic Energy Spectra of Benzyl Fluoride and the Isomeric Fluorotoluenes

1974 ◽  
Vol 52 (6) ◽  
pp. 867-869 ◽  
Author(s):  
S. Safe ◽  
W. D. Jamieson ◽  
D. J. Embree
Keyword(s):  
Mass Spectrometry ◽  
Kinetic Energy ◽  
Mass Spectrometer ◽  
Aromatic Compounds ◽  
Mass Spectra ◽  
Energy Spectra ◽  
Model Compounds ◽  
Free Region ◽  
Field Free Region ◽  
Ion Kinetic Energy

One of the classical problems in mass spectrometry is the structure and formation of the C7H7+ and XC7H6+ ions which are generated in the mass spectra of alkylbenzenes and many other aromatic compounds. The intermediacy of both symmetrical tropylium ion structures and unsymmetrical benzyl ions has been postulated using a number of different approaches. We have investigated this problem using ion kinetic energy spectroscopy, a relatively new technique, with the isomeric fluorobenzenes and benzyl fluoride as model compounds. Our results indicated incomplete substituent (i.e. fluorine) scrambling in the first field-free region of the mass spectrometer and thus incomplete equilibration in the decomposing FC7H6+ ions and these conclusions are in contrast to results obtained using other techniques.

Isotope effects on kinetic energy release. Elimination of CH4 from [CH3CHOH]+ and [CH2OCH3]+

1989 ◽  
Vol 93 (2) ◽  
pp. 215-223 ◽  
Author(s):  
Kevin F. Donchi ◽  
Einar Uggerud ◽  
Georg Hvistendahl ◽  
Peter J. Derrick
Keyword(s):  
Kinetic Energy ◽  
Energy Release ◽  
Isotope Effects ◽  
Kinetic Energy Release
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