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  • 1
    Electronic Resource
    Electronic Resource
    Internal energy effects on the mass spectral fragmentations of some phosphorus heterocycles (1973)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 7 (1973), S. 459-461 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In addition to the elimination of C6H5· and C7H7·, 2,8-dimethyl-10-phenyl- and 10-(p-tolyl)-phenothiaphosphines lost C6H5S· and C7H7S·, respectively from high internal energy molecular ions, while the low internal energy ions eliminated C6H5PH and C7H7PH, respectively. 2,8-Dimethyl-10-phenylphenoxaphosphine lost C6H5·, C6H5P and C6H5PH· both in the source and in the first field-free region, but the expulsion of C6H5O· was not observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210070410
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  • 2
    Electronic Resource
    Electronic Resource
    Structure and fragmentations of [C3H7S]+ ionsPart II: for Part I, see Ref. 1. (1979)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1979), S. 36-45 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The principal fragmentation reactions of metastable [C3H7S]+ ions are loss of H2S and C2H4. These reactions and the preceding isomerizations of [C3H7S]+ ions with six different initial structures were studied by means of labelling with 13C or D. From the results it is concluded that the loss of H2S and C2H4 both occur at least mainly from ions with the structure [CH3CH2CH—SH]+ or from ions with the same carbon sulfur skeleton, with the exception of the ions with the initial structure [CH3CH2S—CH2]+, which partly lose C2H4 without a preceding isomerization. For all ions, more than one reaction route leads to [CH3CH2CH=SH]+. It is concluded that the loss of H2S is at least mainly a 1,3-elimination from the [CH3CH2CH=SH]+ ions. Both decomposition reactions are preceded by extensive but incomplete hydrogen exchange.
    Additional Material: 9 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210140111
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  • 3
    Electronic Resource
    Electronic Resource
    Rearrangements and fragmentations of [C2H5S]+ ions (1978)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1978), S. 232-235 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [C2H5S]+ ions (m/e 61) with different initial structures were generated in the mass spectrometer from twelve precursor ions. Abundance ratios of competing metastable ion decompositions were used to determine whether these ions decompose through the same or different reaction channels. It was concluded that all [C2H5S]+ ions isomerize to a common structure or mixture of structures prior to decomposition in the first field free region. From 13C labelling experiments it was concluded that [C2H5S]+ ions generated from the molecular ions of 2-propanethiol-2-[13C], partially rearrange to a symmetrical structure before decomposition to [CHS]+ and CH4, whereas in [C2H5S]+ ions generated from the the molecular ions of 1,2-bis-(thiomethoxy-[13C]) ethane, the two carbon atoms become fully equivalent before CH4 loss occurs.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210130413
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  • 4
    Electronic Resource
    Electronic Resource
    Rearrangements and fragmentations of phenyl styryl sulfides: 1 - Metastable ion spectra (1982)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 17 (1982), S. 424-429 
    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 two isomeric phenyl styryl sulphides show abundant peaks for fragment ions formed after interesting and unusual rearrangements, e.g. loss of CHS· and C7H7·. Information about these rearrangements was obtained by comparison of the metastable peak intensities and peak shapes with those of four isomers. It appears that isomerization reactions between the phenyl styryl sulfides and the isomers are possible and that most of the metastable ion fragmentations proceed via reacting configurations that are common to two or more of the compounds investigated. The results indicate that an earlier proposed mechanism for the fragmentation of phenyl vinyl sulfides is incomplete and only partly correct for the compounds studied. Metastable ion spectra were obtained using high voltage scans and constant B/E scans: a short comparison of the results obtained with the two methods is given.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210170906
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  • 5
    Electronic Resource
    Electronic Resource
    Fragmentations and rearrangements of metastable [C2H5OS]+ ions (1992)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 27 (1992), S. 1131-1133 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several [C2H5OS]+ ions with different structures were generated from the appropriate precursors and their metastable ion spectra were determined. Deuterium labelled analogues of some of the [C2H5OS]+ ions were used to elucidate the nature of the observed fragmentations and their mechanisms. [C2H5OS]+ ions with different C—O—S skeletons were found to give different fragmentation reactions. There are no indications for fast isomerization reactions leading to common intermediates before fragmentation. Most of the observed fragmentations can occur directly from the initial structures.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210271025
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  • 6
    Electronic Resource
    Electronic Resource
    13C FT-NMR spectra of alkyl substituted furans. A study of the influence of steric interactions (1974)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 461-465 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 13C FT-NMR spectra of thirteen furans, monodi- or trisubstituted with methyl and/or t-butyl groups, were studied in detail. Substituent effects of methyl and t-butyl groups on the chemical shifts of ring carbon atoms are additive in nonsterically hindered furans. Steric shifts for the ring carbon atoms are found in furans with bulky neighbouring substituents, but the hybridisation of the carbon atoms in these hindered furans is not changed. The chemical shifts of the substituents are calculated according to the Grant-Cheney formula. No simple relationship between steric shift and steric hindrance can be ascertained.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270060815
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  • 7
    Electronic Resource
    Electronic Resource
    Ring expansion and hydrogen scrambling in the molecular ion of 3-methylthiophene (1972)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 6 (1972), S. 963-970 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ratio [M — D]/{[M-D] + [M — H]} in the 70 eV mass spectra of six deuterated 3-methylthiophenes has been determined. From these values the mole fractions of the molecular ions that lose hydrogen atoms specifically from the various positions of the molecule were calculated, as well as the mole fraction in which the hydrogen atoms are fully scrambled before hydrogen elimination. It appears that hydrogen atoms are mainly lost from a fully scrambled [C5H6S]+· ion and from the α-position of the original molecular ion. A deuterium isotope effect of 1·60 to 1·72 was calculated for the hydrogen elimination. The reaction was also studied at low electron energies. In order to determine the degree of scrambling in the [C5H5S]+ ions, some decomposition reactions of this ion were investigated.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210060905
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  • 8
    Electronic Resource
    Electronic Resource
    The mass spectrometric fragmentation of α-diazosulphones (1974)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1974), S. 837-839 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fragmentation of four α-diazosulphones under conditions of electron-impact was studied with the aid of high resolution mass measurements and the metastable defocusing technique. An important difference from the spectra of the related α-diazoketones is the absence of peaks for [M — N2]+·. Metastables show, however, that these fragments probably exist as intermediates.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210090813
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  • 9
    Electronic Resource
    Electronic Resource
    Rearrangements and fragmentations of [C2H5S]+ ionsPart II: for Part I, see Ref. 1. (1979)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1979), S. 543-549 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From deuterium labelling experiments it was concluded that metastable molecular ions of ethyl methyl sulfide lose a methyl radical with the formation of both [CH3S=CH2]+ amd [CH3CH=SH]+· The fragmentation reactions of metastable ions generated with these structure are losses of C2H2, H2S and CH4. These reactoins and the preceding isomerizations have also been studied by means of deuterium labelling. From the results it is concluded that the three fragmentation reactions most probably occur from ions with a C—C—S skeleton. Appearance energy measurements for ions generated with the two structures above and all give rise to the same ΔHf value for these three isomeric forms. Ab initio molecular orbitals calculations confirm that these three ions fortuitously have very similar heats of formation. A potential energy diagram rationalizing the isomerizations and the principal fragmentation reaction is presented.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210141006
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  • 10
    Electronic Resource
    Electronic Resource
    Potential energy profiles for the unimolecular reactions of [C3H7S]+ Ions (1980)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1980), S. 229-234 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Appearance energies were measured for several types of [C3H7S]+ ions. From these appearance energy values the heats of formation of the ions were calculated. For the isomeric ions that could not be generated in the mass spectrometer, the heats of formation were estimated by means of the isodesmic substitution method. Transition state energies for the decomposition to C2H4 and [CH3S]+ along two pathways were determined from the appearance energies of these ions. Using the energy values, potential energy diagrams were constructed for the rearrangements and decompositions of the [C3H7S]+ ions. A supplementary 13C Clabelling experiment is described for the determination of the rearrangement pathway of [CH3CH2CH=SH]+ ions prior to decomposition.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210150504
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