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  • Analytical Chemistry and Spectroscopy  (6)
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  • 1
    Electronic Resource
    Electronic Resource
    Heterocyclic studies - XXIX:For Part XXXVIII, see Ref. 1. Mass spectra of some 1,2-dihydro-5-trifluoromethyl-pyrimido(5,4-E)AS-triazines (1973)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 7 (1973), S. 225-231 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass spectra of five 7-substituted-1,2-dihydro-5-trifluoromethylpyrimido(5,4-e)as-triazine derivatives are recorded. Fragmentation pathways, elucidation of which was assisted by deuterium labelling and accurate mass measurements, are compared with those of corresponding heteroaromatic compounds. Loss of HF initiated the major breakdown pathways, unless a large 7-substituent was present, which then fragmented preferentially.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210070212
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  • 2
    Electronic Resource
    Electronic Resource
    Heterocyclic studies - XXX:For Part XXIX, see Ref. 1. Application of mass spectrometry to the study of covalent hydration (1973)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 7 (1973), S. 737-752 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Comparison of the mass spectra of 3,4-hydrated 4-trifluoromethylpteridine derivatives with those of corresponding anhydrous compounds shows that this technique can be used to deduce the position of covalent hydration in heterocyclic compounds.It is less easy to demonstrate the presence of added water molecules in 5,6,7,8-dihydrated derivatives of ethyl pteridine-4-carboxylates, but spectra run at low ionising voltages give the required information.Two hydrates (3,4-hydrates of 4-ethoxycarbonyl- and 4-trifluoromethyl-pteridine-2(1H)-thione) which are very much more thermally stable than usual are also discussed.Metastable peaks and accurate mass measurements support many of the postulated fragmentation pathways.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210070609
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  • 3
    Electronic Resource
    Electronic Resource
    Heterocyclic studies - XXV:For Part XXIV, see Ref. 1. Mass spectra of some 4-trifluoromethylpteridine derivatives (1971)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 5 (1971), S. 1419-1427 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass spectra of 4-trifluoromethylpteridine and nine of its derivatives are recorded. Electron impact induced fragmentations of 4-trifluoromethylpteridine and its 2-chloro-, 7-methyl- and 6, 7-dimethyl-derivatives resemble those of pteridine and simple methylpteridines except that loss of a trifluoromethyl radical usually intervenes at some stage. Fragmentation of 4-trifluoromethyl-pteridine derivatives with an amino, substituted-amino, alkoxy or alkylthio group in the 2-position fragment by a variety of mechanisms. Accurate mass measurements and deuterium labelling were used to help elucidate some fragmentation pathways.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210051209
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  • 4
    Electronic Resource
    Electronic Resource
    Heterocyclic studies - XXVIIIFor Part XXVII, see Ref. 1. Mass spectra of some 5-trifluoromethylpyrimido-(5,4-e)as-triazines (1972)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 6 (1972), S. 467-473 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fragmentation of 7-substituted 5-trifluoromethylpyrimido(5,4-e)as-triazines is dominated by consecutive losses of N2 and HCN from the triazine ring. Deuterium labelling, accurate mass measurements and spectral changes with substitution patterns confirm the fragmentation pathways.Comparison of the spectra with those of corresponding pteridines indicates that the 1,2,4-triazine ring fragments much more readily than the pyrazine ring.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210060502
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  • 5
    Electronic Resource
    Electronic Resource
    Heterocyclic studies - XXII.For Part XXI, see Ref. 1. Mass spectra of some 3-hydroxypteridin-4-ones (1971)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 5 (1971), S. 447-452 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass spectra of 3-hydroxypteridin-4-one and five of its mono-and di-methyl derivatives are recorded. Fragmentation of the non-methyl compound (I; R1 = R2 = R3 = H) occurred mainly by successive losses of NO, CO, HCN and HCN. Changes in m/e values of the major peaks with methyl-substitution pattern in the derivatives were consistent with the proposed fragmentation pattern. Several minor fragmentation pathways were also observed but all involved an initial loss from the oxygen containing ring.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210050410
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  • 6
    Electronic Resource
    Electronic Resource
    Heterocyclic studies - XXIV:For Part XXIII, see Ref. 1. Mass spectra of some pteridin-4(3H)-ones and 3-methoxypteridin-4(3H)-ones (1971)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 5 (1971), S. 993-1002 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass spectra of pteridin-4(3H)-one and all its mono-, di- and tri-C-methyl derivatives are recorded. Spectra of 3-methoxypteridin-4(3H)-one and four of its mono- and dimethyl derivatives are also recorded.Pteridin-4(3H)-one fragments mainly by loss of CO and HCN in either order. Methyl substitution in the pyrazine ring leads to that ring fragmenting in preference to the oxygen bearing pyrimidine ring. Elucidation of fragmentation pathways was facilitated by changes in peak positions with changing methyl substitution patterns.3-Methoxypteridin-4(3H)-ones fragment mainly through initial loss of CH2O, but the ions so produced break down differently from isomeric molecular ions of pteridin-4(3H)-ones. Several fragmentation pathways are discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210050812
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