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  • 1970-1974  (16)
  • 1
    Electronic Resource
    Electronic Resource
    Ortho effects-I: Fragmentation mechanisms in some ortho-substituted nitroarenes (1970)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1970), S. 993-1007 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of o-nitrobenzoic acid, o-nitroanisole, o-nitrosobenzoic acid, o-nitrobenzamide, o-nitrobenzyl alcohol and o-nitrosobenzaldehyde have been studied. Fragmentation mechanisms are proposed for the above compounds; their elucidation was aided by isotopic labeling with D and O18. Two ‘ortho-effects’ are discussed; one involving H atom transfer between substituents and the other migration of an atom or group to a charge carrying vacant ortho position. The importance of nitro to nitrite conversion in molecular and fragment ions is discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210030803
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The mass spectra of isomeric hydrocarbons - I: Norbornene and nortricyclene; The mechanisms and energetics of their fragmentations (1971)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 5 (1971), S. 1349-1362 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of norbornene, nortricyclene and deuterium labeled derivatives thereof have been studied. The appearance potentials of the ions [C7H10]+·, [C7H9]+, [C6H7]+ and [C5H6]+· have been determined for both compounds and heats of formation of the hydrocarbons have been estimated. Detailed fragmentation schemes are proposed for the molecular ions and it is concluded that they dissociate by essentially different mechanisms which do not involve common intermediates. The structures and energy contents of the primary fragment ions are discussed in detail by comparing energetics, labeling experiments and metastable ion abundances.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210051202
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The mass spectra of carboxylic acids - III: The structures of molecular and fragment ions in benzoic acid and related molecules (1970)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 4 (1970), S. 97-107 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of benzoic acid and its carboxyl-deuterated derivative have been studied in detail. Molecular and fragment ion structures are proposed and the role of ortho hydrogen atoms in rearrangements is discussed. The behaviour under electron-impact of phthalaldehydic acid and its carboxyl deuterated derivative provides evidence in support of ion structures in the benzoic acid fragmentation. From these results the fragmentation mechanism for phthalic acid is further elucidated. The mass spectrum and fragmentation mechanism of thiobenzoic acid is described and compared with that of benzoic acid.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210040111
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    A feature of the fragmentation mechanism of exo-2-norbornyl chloride. Stereoselective hydrogen atom abstraction revealed by metastable ion studies (1971)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 5 (1971), S. 1339-1341 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The position of deuterium in the products of the addition of HCL and DCI to exo 5, 6-d2 norbornene has been determined mass spectrometrically by measuring metastable ion abundances. The results show a stereo-selective hydrogen atom abstraction when the molecular ion of exo-2-norbornyl chloride fragements by loss of a chloroethyl radical.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210051111
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Intramolecular amide-amide interaction in the mass spectra of some geometric isomers (1973)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 7 (1973), S. 335-339 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of maleic, fumaric, citraconic, mesaconic and itaconic diamides have been studied. In the molecular ions of the cis isomers, amide-amide interaction does take place, analogous to but less pronounced than, the carboxyl-carboxyl interaction of the corresponding acids.In spite of the weaker interaction a prominent loss of CONH from the molecular ion of a diamide would be strong evidence in support of a cis or similarly rigid geometrical arrangement of the amide groups. The mass spectra of maleic and fumaric nitriles are also reported.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210070312
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  • 6
    Electronic Resource
    Electronic Resource
    Thermochemistry and metastable energy release for the dissociation [C3H7]+ → [C3H5]+ + H2 (1974)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1974), S. 618-621 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reverse activation energy, Erev, for the dissociation [C3H7]+ → [C3H5]+ + H2 has been determined as 0.24 ± 0.06 eV from measurements of the AP of [C3H5]+ produced by electron-impact from thermally generated sec-C3H7 radicals. The energy release observed in the corresponding metastable dissociation is 0.21 ± 0.01 eV, indicating that virtually all of Erev is partitioned as translational Kinetic energy of the fragmentation products. The metastable ion peak shape is also discussed with respect to the evaluation of the energy release.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210090612
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  • 7
    Electronic Resource
    Electronic Resource
    The mass spectra of carboxylic acids-II: Fragmentation mechanisms in the homologous series HOOC(CH2)nCOOH (1970)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1970), S. 1505-1518 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of the homologous series of acids HOOC(CH2)nCOOH from n = 0 to 12 have been studied together with certain deuterium labeled members. The fragmentation mechanisms of the lower homologues are discussed in some detail. The loss of one or two molecules of water from the molecular ions was shown to proceed most favorably via a 6-centred intermediate involving the methylene group β- to a carboxyl function. It was observed that the ease of carboxyl-carboxyl interaction promoting CO2 elimination from the molecular ion could be simply correlated with n and thus serves as a structure-identifying feature.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210031207
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  • 8
    Electronic Resource
    Electronic Resource
    The mass spectra of benzamide and thiobenzamide (1971)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 5 (1971), S. 525-530 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of benzamide, thiobenzamide and their N-d2 analogues have been studied In addition to fragmenting by simple bond cleavages the molecular ions dissociate partly from their imide forms. Equilibration or ‘scrambling’ of ortho ring hydrogen atoms with amide hydrogen did not occur in benzamide but such exchange must take place in the thiocompound whose fragmentation behaviour is very complex. Neither labelled compound produced the label-retaining benzoyl (thiobenzoyl) cation which has been the subject of much interest in the mass spectrum of O-d1 benzoic acid.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210050504
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  • 9
    Electronic Resource
    Electronic Resource
    Specific and random fragmentations in the mass spectra of some neopentyl compounds (1972)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 6 (1972), S. 897-903 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of neopentyl alcohol, bromide and chloride and some 13C and 2H labelled analogues have been studied. Most fragmentations of the molecular ions of these compounds occur by simple bond cleavages and do not involve rearrangement before fragmentation. We propose that in the [M — CH3]+ fragment ions, seven of the eight hydrogen atoms and all four carbon atoms are involved in randomisation when an ethylene molecule is ejected. The eighth hydrogen atom (which comes from a methyl group) is probably associated with the heteroatom. The neopentylcation, observed only in the mass spectrum of the bromide, fragments mainly by loss of an ethylene molecule, also containing randomly selected hydrogen and carbon atoms. The [C4H7]+ ion also was observed to undergo complete atom scrambling.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210060809
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  • 10
    Electronic Resource
    Electronic Resource
    The mass spectrum and fragmentation mechanism of exo- and endo- norborneol (1973)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 7 (1973), S. 559-572 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of exo -and endo-norborneol and a number of deuterium labelled and-logues have been studied in detail. The two alcohols have common fragentation pathways, the major routes of which can be related to specific rearrangements of the molecular ion. The loss of water from the molecular ion consists of two processes, one involving and one4 not involving the hydroxyl hydrogen atom. The limitions of the labelloing experiements are discussed.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210070507
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