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  • Analytical Chemistry and Spectroscopy  (5,382)
  • 1975-1979  (3,254)
  • 1970-1974  (2,128)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 429-435 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Surface roughening by diatomaceous support (5 micron particles deposition) ; Organic glue (polar polymethacrylate acetate) used as intermediate material ; Reproducibility and durability of capillaries discussed ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A technique for adhesion of fine particles (ca. 5 μ) of the 405 white diatomaceous support on the inner wall of glass tube with organic glue [poly (diethylaminoethyl methacrylate) acetate] is described. The coated tube was drawn to capillary column by using a machine designed according to Desty's. The capillary column was then coated with stationary phase (such as squaiane, QF-1, Dexsil 300, PEG 20 M, OV-1, SE 30 and etc.) by the conventional dynamic or static method. This preparation method has proved easy to duplicate and is simple. The coating efficiency (UTE %) is within 60-90. The theoretical plate number per meter of an SE 30 column is about 4000, and per meter of a PEG 20 M column is about 2500. The columns thus prepared have been successfully used to analyze petroleum hydrocarbons, essential oils, petrochemicals, pheromone, steroid metabolites and others.
    Additional Material: 6 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 7 (1975), S. 470-474 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The diastereomers of 16 1,3-oxa-, 1,3-aza- and 1,3- thiaphospholanes were assigned by means of the coupling constants 2J(P—C—H) and 3J(P—C—CH3) and the linewidths of the 31P signals and 1H chemical shifts of CH3 groups. It is shown that the change in the 31P chemical shifts allows the estimation of the relative configuration in these compounds.
    Notes: Die Diastereomeren von 16 1,3 Oxa-, 1,3-Aza-und 1,3-Thiophospholanen wurden mit Hilfe der Kopplungs-konstanten 2J(P—C—H) und 3J(P—C—CH3), der Signalbreite der 31P-Signale und der 1H-chemischen Verschiebungen der CH3-Gruppen zugeordnet. Es wird gezeigt, daß auch die 31P-chemischen Verschiebungen eine Bestimmung der relativen Konfiguration dieser Verbindungen gestatten.
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 568-573 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The geometric factor G [G = (3 cos2 θ -1) r-3] of selected protons relative to a centre of co-ordination [Eu(dpm)3] is determined using Dreiding models of different conformers of 1,3-aza- and 1,3-oxaphospholanes. The centre of co-ordination is supposed to be joined to the oxygen of the carbonyl group or to the nitrogen and oxygen in the hetero-ring, respectively. The graphs of the geometric factors against the paramagnetic shifts of the relevant protons are straight lines only for the preferred conformers on the basis of a correct centre of co-ordination.As a measure for the paramagnetic shift of a proton the slope of the graph of chemical shift against the concentration of Eu(dpm)3 (in mol %) is chosen. By variation of the relative configuration at C-5 in the models and calculation of the geometric factor, it is possible to determine the different diastereomers, which are distinguished by the relative position of the substituent at phosphorus and C-5.
    Notes: An Dreiding-Modellen der verschiedenen Konformere von 1,3-Aza- und 1,3-Oxaphospholanen werden die Geometriefaktoren G [G = (cos2θ - 1)r-3] einzelner Protonen bezüglich eines Koordinationszentrums [Eu(dpm)3] bestimmt. Das Koordinationszentrum wird entweder an dem Sauerstoff der Carbonylgruppe oder an dem Stickstoff oder Sauerstoff im Heteroring gebunden angenommen. Die graphische Darstellung der Geometriefaktoren gegen die paramagnetischen Verschiebungen der betreffenden Protonen ergibt nur für die bevorzugten Konformere bei Zugrundelegung der richtigen Koordinationszentren Geraden. Als Maßzahl für die paramagnetische Verschiebung eines Protons wird die Steigung der Geraden gewählt, die sich beim graphischen Auftragen der chemischen Verschiebung gegen den Gehalt an Eu(dpm)3 (in Mol-%) ergibt. Durch Variation der relativen Konfiguration am C-Atom 5 an den Modellen und Berechnung der Geometriefaktoren ist es möglich, die unterschiedlichen Diastereomere zuzuordnen, die sich bezüglich der Substituentenstellung am Phosphor und am C-Atom 5 unterscheiden.
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  • 4
    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 polyenic compounds of the type RC6H4(CH=CH)nCOPh, n=1, R=H,p-NMe2,p-OH,p-OMe,p-Cl,p-Br,p-NO2,m-NO2; n=2, R=H, p-NMe2, p-OMe,p-Cl,p-Br, p-NO2; n = 3, R = H, p-OMe,p-Cl, p-Br,p-No2 have been measured. The ratio of the intensities of the common ion PhCO (m/e 105) to the intensities of the molecular ions for these series is correlated with the Hammett-Brown equation with reaction constants p = 0.73 (when n = 1), 0.25 (when n =2), 0.11 (when n = 3). The transmission coefficients were calculated as π'=0.72,0.25 and 0.11 respectively [assuming p=1.01 for benzophenone series-see M. M. Bursey and F. W. McLafferty, J. Am. Chem. Soc. 89, 1 (1967)]. The contributions of the inductive mesomeric direct polar conjugation and non-additive interaction were calculated in accordance with the equation log Z/Z0= ρIσI + ρc+σc+ + ρI, cσIσc+. It was found that the inductive influence as well as the mesomeric influence of substituents decreases rapidly with the increase in the number of double bonds in the chain. The direct polar effect has a very small value in all series for all substituents with the exeption of NMe2. Non-additive interaction effects are large. They probably express the general influence of RC6H4(CH=CH)n on COPh.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 423-428 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, nickel ; „Transevaporator“ into packed pre-column as sampling technique prior capillary described ; Application to volatile metabolite body fluid analysis for early detection of disease ; Serum and human breast milk as examples ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nickel capillary columns coated with moderately polarstationary phases such as Witconol can be used for the separation of the organic volatile fraction from biological fluids. A “transevaporator” sampling technique for the collection of the organic volatiles on glass beads from as little as 5 to 500 μl of biological fluids (e.g. urine, serum, amniotic fluid, breast milk, saliva, etc.) is described. The organic volatiles are thermally desorbed from the glass beads into a short precolumn cooled in liquid nitrogen, which overcomes the problems associated with sample introduction onto narrow-bore capillary columns. The application of the full analytical technique to problems associated with the early detection of disease is illustrated.
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1976), S. 388-393 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methane and isobutane chemical ionization mass spectra of ten 2,4,6-trinitroaromatic compounds have been recorded. The mass spectra contain intense [M + 1]+ ions and usually little fragmentation. However, in some cases major fragmentation processes have been observed. Some unusual adduct ions have been found with isobutane as the reagent and their temperature dependence has been studied.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1976), S. 1114-1119 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fatty acids with a hydroxyl moiety at the C-3 position are found widely in bacterial lipids, but only rarely in mammalian lipids. The mass spectra of the methyl ether derivative of these hydroxy acids exhibit an intense ion at m/e 75, rather than the rearrangement ion at m/e 74 more typical of fatty acid methyl esters. The mass spectrometric behavior of several 3-methoxy fatty acid methyl esters were studied, and the origin of the unique ion at m/e 75 was established using 18O and 2H labeled analogs and metastable ion transitions. this ion was shown to arise from the loss of ketene from the 3,4 cleavage ion at m/e 117.
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 346-354 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A large series of cyclohexane and cyclopentane spiro compounds has been studied by carbon-13 NMR. Increments have been derived in terms of α, β, γ spiro substituent effects, one ring being considered as the substituent of the other. As usual α and β effects are paramagnetic and γ effects are diamagnetic. They are compared with the corresponding effects associated with the introduction of a gem dimethyl group into a cyclohexane or cyclopentane ring. The size of the two rings involved in the spirane structure has a marked influence especially on the chemical shift of the spirane carbon atom. Comparison between monospiro and dispiro derivatives gives information about the so-called 1,5 or δ effect which is paramagnetic. From an analytical point of view, carbon-13 NMR appears to be a powerful method of detecting the spirane structure, apparently including the relative size of the rings.
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 492-493 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The 13C NMR spectral study of epoxy bicyclo [2.2.1]-heptanes reveals a strong influence on the chemical shift of the bridging 13C, due to the endo or exo orientation of the heterocyclic ring. The difference between the 13C and 1H Δδ shows that the observed results cannot be explained by the ring current alone.
    Notes: L'étude RMN 13C de composés époxybicyclo[2.2.1]-heptaniques fait ressortir une forte influence de l'orientation endo ou exo de l'hétérocycle sur le glissement chimique du 13C pontal. La différence entre les variations de glissements chimiques en 13C et 1H montre que l'effet de courant de cycle ne peut seul rendre compte des résultats observés.
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 4 (1977), S. 155-158 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of antipyrine metabolites show characteristic fragmentation patterns which depend on the presence and position of functional groups. A substituent at position 4 is indicated by an intense key fragment at m/e 56 and a substituent at the methyl group in position 3 causes a significant increase in the intensity of the peak at m/e 82. The fragment at m/e 96, which is characteristic for antipyrine itself, is suppressed if there is a substituent in either position 3 or 4. Mass spectra of the glucuronides of 4-hydroxyantipyrine and 3-hydroxymethylantipyrine are also discussed.
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  • 11
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1978), S. 65-73 
    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 nine diastereoisomeric pairs of 4-methyl-2-X-2-Y-1,3,2-dioxaphosphorinanes have been examined. The differences between the intensities of particular ions in the mass spectra of geometrical isomers are reported and rationalized in terms of the conformations adopted by compounds.
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  • 12
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Raman scattering of two vibrational overtones of benzene is found to undergo strong preresonance enhancement as the excitation frequency approaches the 1B2u state, the lowest lying, forbidden electronic transition at 265 nm. These preresonance active modes are the first overtone of the 606 cm-1 e2g fundamental, which is responsible for the vibronically induced 1B2u intensity, and the first overtone of the 848 cm-1 e1g fundamental, an out-of-plane C—H bending mode. In order to treat this overtone preresonance Raman behavior theoretically, the molecular polarizability is consistently expanded to second order in nuclear displacements, and thus we consider all preresonance contributions of this order. The leading contributions of strictly dipole-forbidden electronic transitions to the scattering cross-section of overtones are exposed. Within this theoretical context it is seen how scattering cross-section for each of these resonance active overtones is derived from different sources. The preresonance scattering of the 606 cm-1 overtone results from the vibronic activity of this fundamental in the 1B2u transition. On the other hand, the 848 cm-1 overtone derives its 1B2u resonance activity from the change in its fundamental frequency (to 585 cm-1) in this excited electronic state. Furthermore, the 848 cm-1 overtone activity is built upon signifficant background preresonance contributions from other higher lying electronic transitions.
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  • 13
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 5 (1976), S. 181-192 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Vibronic coupling of the Herzberg-Teller type is discussed as a possible source of the depolarization dispersion of a fundamental line of a totally symmetric vibration in resonance Raman scattering (RRS). Two cases are discussed separately. The first case concerns RRS from an electronic state that borrows part of its intensity from a non-overlapping electronic state of different symmetry. In this case the depolarization ratio of the fundamental line for right angle scattering linearly polarized light can vary between the limits 1/8 and 3/4. The second case arises when part of the intensity is borrowed from an electronic state of the same symmetry but with a transition moment non-parallel to that of the resonant state. Such a situation can occur in molecules with a symmetry corresponding to one of the following point groups: C1, Ci, C2, Cs, C1h, C2h, S2. In this situation the depolarization ratio ρl can vary between the limits 1/8 and. In both cases the amplitude of the variations of ρl depends on the damping constant. In the second case the value of the displacement parameter of a totally symmetric mode has a major influence on the range of change of ρl. Both cases show prominent resonance-antiresonance coincidences between depolarization dispersions and excitation profiles, which has been previously predicted for non-totally symmetric modes, and for molecular dimers. It is pointed out that the depolarization ratio in the preresonance region is very sensitive to vibronic coupling and can serve as a probe of such coupling.
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  • 14
    Electronic Resource
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    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 6 (1977), S. 53-56 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The theory of interference effects between preresonance scattering from an intense electronic transition and resonance scattering from a forbidden electronic transition is formulated. A simple closed formula for the cross-section of a totaliy-symmetrical fundamental line is derived for the case where the vibrational structure of both electronic transitions is smeared out. This formula reproduces very well recently obtained experimental excitation profiles in such complex compiunds as tris (ethylenediamine) cobalt (III) chloride and tetrabromopalladate ion.
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  • 15
    Electronic Resource
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    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 4 (1972), S. 585-589 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Proton and carbon-13 spectra of benzyl compounds of the general formula (C6H5CH2)nX with a large variety of X substituents have been measured. While a linear relationship between the CH2 chemical shift and the substituent electronegativity was found both for 1H and 13C, large deviations from linearity were observed for transition metals such as titanium and zirconium. These later results are correlated with the X-ray studies of the latter compounds.
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  • 16
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 9 (1977), S. 218-223 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformations of dihydrolysergamides and 10-methoxydihydrolysergamides have been inferred from the study of the chemical shifts of the amide hydrogens and their temperature dependence. The 13C chemical shifts have been shown to be sensitive to conformational changes of the piperidine ring. The results indicate that the conformation of the latter depends both on the substituent in position 10 and on the solvent.
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  • 17
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The field desorption mass spectra of eight rifamycins were obtained and compared with their electron impact mass spectra. All the compounds gave abundant molecular or quasimolecular ions, while no significant fragmentation was observed in the low mass region of the spectra. Therefore, field desorption mass spectrometry has been shown to be of great importance for the determination of the molecular weight of these antibiotics.
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  • 18
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1974), S. 1062-1062 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 19
    Electronic Resource
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1978), S. 43-50 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Gas chromatography mass spectrometry was used to examine a large number of 2,4,6-trialkoxy-s-triazines. The fragmentation of these compounds upon electron impact is discussed. This method permits reliable and rapid identification of mixtures of triazines obtained by reaction of 2,4,6-trichloro-s-triazine with mixtures of alcohols.
    Notes: Zahlreiche 2.4.6-Trialkoxy-s-triazine wurden mittels Gaschromatographie-Massenspektrometrie untersucht. Die Fragmentierung dieser Verbindungen bei Elektronenbeschuß wird diskutiert. Die Methode erlaubt, komplexe Triazingemische, die bei der Umsetzung von 2.4.6-Trichlor-s-triazin mit Alkoholgemischen entstehen, schnell und sicher zu identifizieren.
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  • 20
    Electronic Resource
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1978), S. 248-253 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The fragmentation of the homologous fatty acid tetraesters of pentaerythritol (C-2 to C-14) upon electron impact was investigated. The main fragment ions are [M—RCOO]+ and [M—RCOOH]+, for which cyclic acetal structures are postulated. Subsequent fragmentation was elucidated by ‘direct analysis of daughter ion’ (DADI) measurements and high resolution measurements. Esters of branched fatty acids can be distinguished from esters of n-fatty acids by characteristic ions. Isomeric esters of n-fatty acids cannot be separated by gas chromatography but identification is also possible by mass spectrometry.
    Notes: Die Fragmentierung der homologen Fettsäuretetraester des Pentaerythrits (C-2 bis C-14) bei Elektronenbeschuß wurde untersucht. Hauptspaltfragmente entstehen durch [M—RCOO]+ und [M—RCOOH]+. Diese Ionen liegen vermutlich als cyclische Acetale vor. Der weitere Zerfall dieser lonen wird anhand von DADI-Messungen und Massenfeinbestimmungen geklärt. Ester verzweigter Fettsäuren können anhand charakteristischer Ionen von solchen aus n-Fettsäuren unterschieden werden. Die massenspektrometrische Identifizierung von isomeren n- Fettsäureestern, die gaschromatographisch nicht aufgetrennt werden können, ist ebenfalls möglich.
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  • 21
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1976), S. 1313-1314 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 13C labelling of position 4 in homoadamantane shows that in the electron impact induced elimination of CH3 from the molecular ion each carbon atom of the CH2-CH2 bridge participates to the extent of 25%.
    Notes: Durch 13C-Markierung der Position 4 des Homoadamantans wird gezeigt,daß bei derelektronenstoß-induzierten CH3-Abspaltung aus dem Molekül-Ion jedes Kohlenstoff-Atomder CH2-CH2-Brücke zu 25% beteiligt ist.
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  • 22
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1975), S. 317-319 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The electron-impact-induced fragmentation of naphthalene-2,1-diazooxide shows the stepwise elimination of N2 and CO like other α-diazoketones. From the mass spectrum of lh13C-naphthalene-2,1-diazooxide, it is concluded that no oxirene species participates in the [M — N2]+· ions.
    Notes: Napthalin-2,1-diazooxid eliminiert unter Elektronenstoα---wie andere α-Diazoketone-schrittweise N2 und CO. Das Massenspektrum von 1-13C-Naphtalin-2.1-diazooxid zeigt, daß keine Oxiren-Spezies zu den [M — N2]+·-Ionen beiträgt.
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  • 23
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 5 (1971), S. 373-381 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectra of some alkyl-,aryl-, acyl-and aroyl-substituted 1,2,3-thiadiazoles and ofbenzothiadiazole are reported and interpreted. After the elimination of N2 from the molecular ion a rearrangement of the [M - N2]+.-ion occurs producing a thioketenion-radical. Some of the subsequent fragmentation processes demand this structure. Additionally expulsion of S and ·SH respectively from the non-rearranged [M - N2]+.-ion is discussed.
    Notes: Die Massenspektren einiger alkyl-, aryl-, acyl- und aroylsubstituierter 1,2,3-Thiadiazole und des Benzothiadiazols werden mitgeteilt und interpretiert. Nach der Abspattung von N2 aus dem Molekiilion erleidet das [M - N2]+.-ion eine Art WolRsche Umlagerung zu einem Thioketen-Ionen-Radikal. Ais Beweis wird die Bildung von Fragmentionen angefiihrt, die eine solche Umlagerung voraussetzen. Außerdem wird die Eliminierung von S bzw. ·SH aus dem nicht ungelagerten [M - N2]+.-Ion diskutiert.
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  • 24
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The formation of the [M—43]+ ion in equilenin is due mainly to elimination of Me radical from the [M—CO]+ ion and, to a lesser extent, to CO loss from the [M—Me]+ ion. In 14β-isoequilenin the [M—CO]+ ion is absent, and the formation of [M—43]+ occurs via the [M—Me]+ ion. This makes the determination of the mode of junction of the rings C and D in the equilenin series possible, using high resolution mass spectra, even when only one stereoisomer is available.
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  • 25
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectral fragmentation of p-nitrobenzoyl esters of vitamin D3 stereoisomers has been investigated. The differences in the intensities of the main characteristic ions provide a basis for (E)- or (Z)-configurational assignments to the compounds of this series.
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  • 26
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The metastable/daughter ion ratios, [m*]/[D+], for dipeptides were measured in the first field free region. The [m*]/[D+] values were found to be influenced by the amino acid sequence in peptide molecules.
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  • 27
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ionization potentials of methyl ethers of D-homoequilenine, its 14ß-isomer, D-homoestrone and its 8°-isomer, as well as appearance potentials of certain fragment ions have been determined by means of electron-impact. The dissociation energies of the bonds which are split in the course of formation of these ions have been calculated.
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  • 28
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    Organic Magnetic Resonance 4 (1972), S. 1-25 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described which permits the analysis of many substituted benzene compounds. The method is useful for mono-through tetra- substituted aromatics. In ideal cases, the number and disposition of the substituents and the chemical shifts of the residual protons can be accurately determined. The method assumes approximate first order couplings and is useful for roughly 50% of all aromatics. Frequently observed anomalous spectra are also discussed.
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  • 29
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    Biological Mass Spectrometry 11 (1976), S. 675-679 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using the stereoisomeric 1,2-dimethyl-4-alkyldecahydroquinol-4-ols and various examples described elsewhere it was shown that there are many cases when decreasing of the electron energy does not lead to an increase in the quantitative differences between the mass spectra of stereoisomers.
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  • 30
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The main fragmentation pathways of the N-1, C-2 and C-4 stereoisomers of the 1,2-dimethyl-4-R-transdecahydroquinoline-4-ol N-oxides (R=C≡CH, CH=CH2 and C2H5) under electron impact are discussed. The correlation between the mass spectrometric chromatographic behaviour and the configuration of polar groups in the N-oxides examined is discussed. The mass spectra of the N-1 stereoisomers may be subdivided into two groups, depending only on the orientation of N→O group and not of the 4-OH group. The spectra of N-oxides with the axial N-oxide group reveal less intense ions and much more intense [M—CH3]+, [M—O]+, [M—OH]+ and ions, whereas in the spectra of their equatorial epimers the abundance of the ions exceeds the intensities of the latter ions.
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  • 31
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    Biological Mass Spectrometry 13 (1978), S. 366-367 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The elimination of C2H6 from the molecular ions of trans-fused 2- and 3-ethylbicyclo [4.4.0] decanes with the axial C2H5 group takes place to a greater extent than in the corresponding equatorial epimers.
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  • 32
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ionization potentials for the stereoisomers of trans-fused 2- and 3-methylbicyclo[4.4.0]decanes and the appearance potentials for the ions at m/e 137 [M-CH3]+, 109, 96, 95 and 82 were measured by the electron impact method. The ionization potentials and appearance potentials of the [M-CH3]+ ions appeared to be equal for each of the epimers. Appearance potentials of the other ions were always lower for the less stable epimer. No quantitative correlation was observed between the difference in the appearance potentials for any ions and the differences in enthalpies of the ground states.
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  • 33
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ionization potentials for the stereoisomers of trans-fused 1,2-dimethyl- and 1-ethyl-2-methyl-4-R-decahydroquinol-4-ols (R=C≡CH, CH=CH2 or C2H5) and the appearance potentials for the [M-CH3]+ and [M-C2H5]+ ions (loss of 2-CH3 and 4-C2H5 groups potential, respectively) were measured by using the electron impact method. The ionization and appearance potential for [M-CH3]+ are always lower for the isomers with the axial 2-CH3 group. For the C-2 epimers, the difference between the appearance potentials for the [M-CH3]+ ion values is likely to be equal to the enthalpy differences between the ground states of the epimers and the dissociation energy differences between the axial and equatorial C2-CH3 bonds. The appearance potentials for [M-C2H5]+ for the C-4 epimers possessing the 4-C2H5 group were very similar. At the same time, the appearance potentials for the [M-CH3]+ ions were lower for less stable epimers which had an axial 4-C2H5 group.
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  • 34
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The ion intensity ratios from competing α-fissions of 30 tertiary aliphatic alcohols and 24 ethers of tertiary alcohols have been measured at 13 eV. The intensity ratios of ions [M — alkyl1]+ and [M — alkyl2]+ agree well with the reciprocal mass ratios of the respective ions in the case when the alkyl groups are not methyl (ion mass effect). The intensity ratios of [M — alkyl]+ and [M — methyl]+ are always too high, but intensity ratios of [M — alkyl1]+ and [M — alkyl2]+ may be derived indirectly from them, which also agree well with those values expected from the ion mass effect. By the indirect method it is shown, that for the 2,2-dialkyl-1,3-dioxolanes (ethylene ketals) the ion mass effect plays a dominant role too.
    Notes: Von 30 tertiären aliphatischen Alkoholen und 24 Äthern teriärer Alkohole wurden die Ionenintensitätsverhältnisse aus konkurrierenden α-Spaltungen bei 13 eV gemesen. Die Intensitätsverhältnissen der Ionen [M — Alky1]+ und [M — Alkyl2]+ bei Alkyl stimmen mit den reziproken Massenverhältnissen der zugrundeliegenden Ionen gut überein (Ionenmasseneffekt). Die Intensitätsverhältnisse von [M — Alkyl]+ und [M — Methyl]+ sind immer zu hoch, doch lassen sich aus ihnen indirekt Intensitätsverhältnissen von [M — Akyl2]+ bestimmen, die ebenfalls gut mit den Werten anch dem Ionenmasseneffekt übereinstimmen. Durch die indirekte Bestimmungsmethode wird gezeigt, daß auch bei den 2,2-Dialkyl-1,3 dioxolanen (Äthylenketale) der ionenmasseneffekt eine dominierende Rolle spielt.
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  • 35
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The ion intensity ratios from α-fissions of N-t-alkylethylamines are independent of electron energy above 18 eV and they directly follow the ‘ion mass effect’ in this region. The course of the intensity ratios over the whole energy range can be explained by combination of appearance energy differences and the ion mass effect. In the upper energy region the increase of the ion intensity ratios I(M—Rlarge): I(M—Rsmall) normally found with increasing electron energy is mainly caused by successive decomposition of the ions. This is shown from investigations of N-t-alkylacetamides. A correlation is found between the masses of the primary ions and the tendency towards secondary ion formation, and the internal energy of the primary ions is found to have an influence too. The ‘ion mass effect’ is not a direct effect of the ion masses.
    Notes: Die Ionenintensitätsverhältnisse aus α-Spaltungen von N-t-Alkyl-ethylaminen sind oberhalb 18 eV unabhängig von der Elektronenenergie und gehorchen in diesem Bereich dem ‘Ionenmasseneffekt’. Der Verlauf der Intensitätsverhältnisse über den gesamten Energiebereich kann durch Zusammenwirken von Auftritts-energie-Differenzen und Ionenmasseneffekt erklärt werden. Anhand der N-t-Alkyl-acetamide wird gezeight, daß der übliche Anstieg der Intensitätsverhältnisse I(M—Rgroß): I(M—Rklein) mit zunehmender Elektronenenergie im oberen Energiebereich hauptsächlich durch den Weiterzerfall der Ionen verursacht wird. Für die Bildungstendenz der Sekundärionen wird ein Zusammenhang mit den Massen sowie offenbar mit der inneren Energie der Primärionen festgestellt. Der ‘Ionenmasseneffekt’ ist kein direkter Effekt der Ionenmassen.
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  • 36
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The dependence of ion intensity ratios of competing α-fissions on electron beam energy, source temperature, influences of electron multiplier and ion optics, were investigated. A mass discriminating effect of the ion optics was found. It is shown that the ion mass effect found on tertiary aliphatic alcohols is real. So far as it is known today, this effect is pronounced in such aliphatic compounds which exhibit no molecular ion peak under electron impact and form very stable ions by α-fission. Two alternative explanations are proposed.
    Notes: Die Abhängigkeit der Intensitätsverhälthisse aus konkurrierende α-spaltungen von experimentellen Einflüssen, wie Electronennergie, Quellentemperatur, SEV- und Fokussierungsbedingungen wird untesucht. Ein Massendiskriminierungseffekt der Ionenoptik wird gefunden. Es wird gezeigt, daß der an tertiären aliphatischen Alkoholen gefundene [Ionenmasseneffekt] echt ist. Er tritt nach den bisherigen kenntnissen deutlich bei solchen aliphatischen Verbindungen auf, die unter Elektronenstoß keinen Moleküpeak zeigen und sehr stabile Ionen aus der α-spaltung bilden. Zu seiner Erklärung werden zwei alternative Vorschläge angeboten.
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  • 37
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The identification of a number of metabolites of the novel antiarrhythmic agent, α,α-dimethyl-4-(α,α,β,β-tetrafiuorophenethyl)benzylamine (MK-251), is presented. The compound is extensively metabolized by dog, monkey, baboon and man. Similar metabolic profiles were obtained for all species. Isolation and purification were accomplished by solvent extraction and chromatographic (column, gas and thin-layer) procedures. Gas chromatography, derivatization, infrared, nuclear magnetic resonance and particularly combined gas chromatography low and high resolution mass spectrometry techniques were employed to characterize the metabolites. The major urinary and plasma metabolites were identified as 2-[4-(α,α,β,β-tetrafluorophenethyl)phenyl]-2-propanol and its glucuronide conjugate. Other metabolites characterized were: the N-glucuronide of MK-251; 2-[4-(α,α,β,β-tetrafluorophenethyl)phenyl]propene; 2-nitro-2-[4-(α,α,β,β-tetrafluorophenethyl)phenyl]propane; α,α,β,β-dimethyl-4-(α,α,β,β-tetrafluorophenethyl)benzyl methyl ether; and 4-(α,α,β,β-tetrafluorophenethyl)acetophenone. The O-methyl ether metabolite represents the first instance of in vivo alkylation of a tertiary alcohol. Tentative identification was made for the N-hydroxy analog of MK-251 and for the glycol analog of 2-[4-(α,α,β,β-tetrafluorophenethyl)phenyl]-2-propanol. The observed pharmacological response appears to result mainly from MK-251 and not from the four metabolites.
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  • 38
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    Journal of Raman Spectroscopy 6 (1977), S. 227-234 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Infrared and Raman spectra of [Ni(NH3)6]X2 compounds were measured at temperatures from 80 K to 300 K in the frequency range below c. 400 cm-1. Besides the simple bands previously reported additional ones were seen, especially at lower temperatures. The broad band which appeared between the lattice vibration and the δ(NNiN) deformation vibration was interpreted as partly representing the phonon density distribution from the whole Brillouin zone. Its appearance is induced by crystal imperfections connected with NH3 vacancies. Additíonal bands between δ(NNiN) deformation vibration and ν(NiN) stretching, and those above the ν(NiN) stretching were interpreted as combination bands in which the lattice vibration combines with the deformation in the former case and with the stretching mode in the latter. A satellite band close to the ν(NiN) stretching was interpreted as a combination of the stretching and libration mode of the whole [Ni(NH3)6]2+ ion. A model correlation function describing the librations was fitted to the experimental correlation function obtained from the i.r. spectra.
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  • 39
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The temperature dependence of NQR frequencies and spin-lattice relaxation times in Menshutkin's complexes, prepared on the basis of AsCl3 and AsBr3 have been investigated.The rotational oscillation frequencies νt and the average life times τa of rotational oscillation quanta have been calculated by both the Bayer and Woessner-Gutowsky theories.
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  • 40
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    Biological Mass Spectrometry 12 (1977), S. 98-99 
    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 1-adamantyl substituted carboxylic acids and alcohols with and without deuterated hydroxyl groups were studied. Deuterium exchange between functional group and adamantane nucleus was observed and a possible explantation of the phenomenon is given.
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  • 41
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    Biological Mass Spectrometry 3 (1970), S. 1401-1410 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Homoadamantane derivatives can be divided into two groups according to their mass spectra. To the first group belong compounds with electron attracting substituents (COOH, CI, COOCH3, Br); compounds with electron releasing substituents (OCH3, OH, NH3, NHCOCH3) constitute the second group.The most characteristic feature of the first group compounds is the splitting off of the substituent. The hydrocarbon fragment [C11H17]+ thus formed then loses olefin molecules with the formation of corresponding ionic species C11-nH17-2n. The 3-substituted compounds of this group undergo thermal Wagner-Meerwein type rearrangements into adamantane derivatives, resulting in the [C10H15]+ (m/e 135) ion formation; this is the main difference between 1- and 3-substituted homoadamantanes.The series of [CnH2n-6X]+ ions (where X = OCH3, OH, NH2, NHCOCH3, n = 6 to 10) are characteristic of the mass spectra of the second group compounds, the ion [C6H6X]+, [M — C5H11]+ being the most abundant. The intensity ratio of [M — C5H11]+ to [M — C4H9]+ ions is 10:1 for 1-substituted and 3:1 for 3-substituted compounds of this group, allowing the location of the substituent. Some individual features of the spectra are also reported.
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  • 42
    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 1,1-dimethyl-1-silacyclobutane (I - as reported by Cherniak et al.),6, 1,1-dimethyl-1-germacyclobutane (II), 1,1,2,2-tetramethyl-1,2-disilacyclopentane (III) and 1,1,2,2-tetramethyl-1,2-digermacyclopentane (IV) are compared and some correlations between electron-impact fragmentation and thermal decomposition are derived. The mass spectra of the germanium compounds with respect to the silicone compounds are enriched by light fragment ions and exhibit lower intensities of odd-electron ions. The composition of some ions and apparently of neutral fragments coincides with that of the unstable intermediates which are suggested in the thermal decomposition mechanism of some related compounds. The loss of C2H4 is more characteristic under electron-impact as well as in thermal decomposition of Si-compounds, while C3H6 is preferable eliminated by the Ge-compounds.
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  • 43
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    Biological Mass Spectrometry 8 (1974), S. 267-277 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The suitability of n-hexane and n-octane as reactant gases in chemical ionization mass spectrometry has been investigated. The mass spectra of these substances have been investigated as a function of pressure up to 2·4 Torr for n-hexane and 1·7 Torr for n-octane. The major ion present in n-hexane at 0·8 Torr is [C6H13]+ (m/e 85) with a relative intensity of 0·65. In n-octane at 0·8 Torr the major ions are [C8H17]+ (m/e 113), [C6H13]+ (m/e 85) and [C5H11]+ (m/e 71). The relative intensities of these ions are 0·38, 0·12 and 0·19, respectively. These alkyl ions in both n-hexane and n-octane are thought to have tertiary structures. Rate constants for the rates of reaction of the primary ions in the two compounds have been determined.The n-hexane chemical ionization spectra of 26 compounds were determined. The spectra of polar compounds are dominated by proton transfer, whereas those of nonpolar compounds exhibit proton transfer and in addition often surprisingly large amounts of electron transfer. The n-octane chemical ionization spectra of 15 compounds were determined and the spectra in general are quite similar to those obtained with n-hexane. n-Hexane and n-octane can be used as reagents in analytical chemical ionization mass spectrometry, but except in certain specialized uses they would probably have no advantage over i-butane.
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  • 44
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    Biological Mass Spectrometry 4 (1970), S. 147-155 
    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 cis- and trans-decahydroquinoline, their N-methyl and their N-benzoyl derivatives have been examined. Several deuterated derivatives of the N-methyl compounds and one C-methyl derivative have been prepared and a study of their spectra has aided in the interpretation of the mechanism of fragmentation. The major fragment ions are formed by loss of two, three and four carbon fragments from the homocyclic ring.
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  • 45
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    Biological Mass Spectrometry 6 (1979), S. 253-259 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Following intraperitoneal administratin to rats of [14C]loperamide, [carbonyl-14C] 4-(p-chlorophenyl)-4-hydroxyl-N,N-dimethyl-α,α-diphenyl-1-piperidinebutyramide, metabolites in feces and urine were separated, and identified by means of mass spectrometry. In feces, six metabolites were identified in addition to the unchanged drug. The main metabolic pathways involved are dealkylation in the dimethyl amide moiety to give desmethyl- and didesmethylloperamide, both of which were in turn monohydroxylated either in the α-phenyl ring or possibly in the α-carbon in the piperidine ring. It is noteworthy that metabolites hydroxylated in the piperidine ring were isolated as pyridinium derivatives, possibly due to spontaneous aromatization of its 2,4-dihydroxy-4-(p-chlorophenyl)piperidine ring. In urine, only two metabolites were found and identified to be desmethyl- and didesmethylloperamide, since [14C]loperamide was excreted into urine only in a small amount.
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  • 46
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    Biological Mass Spectrometry 6 (1979), S. 191-193 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In water soluble substances obtained by water extraction from human skin surface, free glycerol was detected by gas chromatography mass spectrometry. A selected ion monitoring method was employed to measure low concentration of free glycerol and the mean amounts were found to be about 0.7 μg cm-2 on the cheek and 0.2 μg cm-2 on the forearm and sole.
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  • 47
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemical ionization mass spectra of four explosive compounds have been obtained by using water as reagent gas. The compounds are 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane, 1,3,5-trinitor-1,3,5-triazacyclohexane, pentaerythritol tetranitrate, and an explosive which has been used in letter bombs, containing the two latter compounds and a plasticizer. The chemical ionization H2O mass spectra were recorded at an ion source temperature range of 170 to 225°C, a probe temperature range of 160 to 265°C and a reagent gas (H2O) pressure range of 0.07 to 0.10 Torr. Unlike in chemical ionization using methane or isobutane, chemical ionization H2O spectrum of these compounds provides a method for obtaining quasimolecular peaks. Adduct ion peaks like [M + H3O]+, [M + H5O2]+, [M + NO]+ and [M + NO2]+ are also observed in the chemical ionization H2O mass spectra of these compounds. Chemical ionization H2O mass spectra provide thus a better means of explosive identification.
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  • 48
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    Biological Mass Spectrometry 2 (1975), S. 279-280 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A pressure measuring probe has been built for the chemical ionization source of a Du Pont 21 490-B mass spectrometer. The probe fits exactly in the place of the solid sample probe and, when connected to a Baratron manometer, enables pressure measurement directly in the source. This can be used to calibrate an ionization gauge connected to the source housing or a manometer in the reagent gas inlet line. The probe has been used to determine the maximum source pressure attainable for various reagent gases in the Du Pont 21 490-B mass spectrometer.
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  • 49
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    Biological Mass Spectrometry 13 (1978), S. 167-171 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formation of ions in chemical ionization mass spectrometry of flavonoid compounds has been studied. Production of adduct ions and fragment ions as a function of ring substituents and of reagent gas has been observed. Pressure and repeller field dependence of ions has been found as a function of ring substituents.
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  • 50
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    Biological Mass Spectrometry 6 (1979), S. 465-466 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 51
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    Biological Mass Spectrometry 5 (1978), S. 47-51 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new methodology has been applied to the analysis of human white blood cells obtained both from donors with normal white cells and from donors having one of several cytologically identified leukemias. The analytical process makes use of evolution patterns of molecular fragments generated during the well controlled degradation of the cells. The process has been shown to be effective both in grouping together malignant cells that originate from the same diseases and in distinguishing between malignant cells originating from different diseases. The reproducibility of the method has been demonstrated.
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  • 52
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    Biological Mass Spectrometry 5 (1971), S. 135-146 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular ions of phenyl benzoate, methyl benzoate, t-butylbenzene, phthalic anhydride, p-dimethoxybenzene, o-dimethoxybenzene and acetophenone each undergo two consecutive reactions ([M]+.→[A]+→[B]+). These unimolecular reactions are treated within the framework of the quasi-equilibrium theory (QET); a simple modification of the original equation relating the rate constant (k) with the internal energy (E) was used to calculate mass spectra of the above compounds from 12 to 20 eV. Good agreement between calculated and observed spectra is obtained.
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  • 53
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    Biological Mass Spectrometry 9 (1974), S. 1063-1072 
    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 morellin and other related natural products, isolated from the various Garcinia species, have been recorded and the data has been rationalised. The characteristic cleavage is the opening of the bicyclo(2.2.2) octenone ring system by a retro-Diels-Alder reaction. The γ-pyrone ring also undergoes the retro-Diels-Alder fragmentation. These two modes of cleavage indicate the different substituents on the main skeleton of morellin. The hydrogenated derivatives show slight variations in their fragmentation modes. The mass spectral data assists considerably in the structural elucidation of similar complex molecules, if isolated in minute quantities.
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  • 54
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    Organic Magnetic Resonance 12 (1979), S. 87-91 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The noise-decoupled nitrogen-15 NMR spectra of ten pyridine N-oxides and two quinoline N-oxides have been obtained at the natural-abundance level by high-resolution NMR spectroscopy. Substituents at the 4-ring position of pyridine N-oxide, capable of resonance interaction with the N-O moiety, give fairly large shifts in the expected directions. Spectra taken in dimethyl sulfoxide solution give 5-20 ppm and 33-55 ppm downfield shifts with respect to the solutions of the same substances in 2,2,2-trifluoroethanol and trifluoroacetic acid. Solvent influences are discussed in terms of hydrogen bonding and protonation of the N-oxide oxygen. Carbon-13 chemical shifts and one-bond carbon-hydrogen coupling constants of some substituted pyridine N-oxides are reported and discussed.
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  • 55
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    Organic Magnetic Resonance 12 (1979), S. 340-342 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 15N NMR spectra of ten isocyanates, four isothiocyanates, and four N-sulfinylamines have been obtained at the natural-abundance level by high-resolution NMR spectroscopy. The results show that isocyanates and isothiocyanates have 15N chemical shifts over 200 ppm toward higher fields compared to those of N-sulfinylamines. The sensitivity of the 15N shifts in these substances to substituent and electronic effects are discussed.
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  • 56
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    Biological Mass Spectrometry 3 (1970), S. 23-29 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Many reports on the mass spectra of organotransition-metal complexes have appeared in recent years,1 whilst there have only been a few reports on the mass spectra of transition metal olefin complexes, some metal carbonyl olefin complexes234 and π-cyclooctenyl-π-cyclooctadienyl cobalt.5 Recently fragmentation paths of π-cyclopentadienyl-cyclooctadiene rhodium were elucidated by King.6 The present authors found metastable ions in the mass spectra of π-cyclopentadienyl-diene cobalt complexes as well as in the mass spectra of π-cyclopentadienyl-diene rhodium complexes.7.In the present paper the authors wish to report the mass spectra of several π-cyclopentadienyl diene cobalt complexes.
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  • 57
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    X-Ray Spectrometry 7 (1978), S. 23-25 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The Kα1,2, Kβ1,3, Kβ5, and Kβ″ emission spectra of vanadium in the element and several V (III), V(IV), and V(V) compounds have been measured with a two-crystal X-ray spectrometer. The Kα1 and Kβ1,3 peaks shift slightly to lower energies with increasing lthe oxidation state of vanadium atom and the Kβ5 peak shifts to higher with it. An approximately linear relationship between Kα1 width and Kα1/Kα2 intensity ratio can be used for lindentification of vanadium oxidation state.
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  • 58
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas chromatographic separation and mass spectrometric identification of mycolic acids ranging from C28 to C68 in Nocardia and related acid-fast groups of bacteria was established. Using this method, the molecular species of mycolic acids were clearly separated as the trimethylsilyl (TMS) derivatives of the methyl esters, according to their total carbon numbers. From the ions produced by gas chromatography mass spectrometry, the total carbon and double bond numbers were determined, while the straight and branched chain structures were identified by the mass fragment ions due to C2 ∼ C3 cleavage [R—CH—O—Si—(CH3)3]+, and C3 ∼ C4 cleavage [(CH3)3—Si—O—CH—CH(R′)—COOCH3]+, respectively. Based on the molecular species composition, the average carbon numbers of the mycolic acids from 16 strains of Nocardia and related taxa (Mycobacterium rhodochrous complex and Gordona bronchialis) were determined. Each species of bacteria was demonstrated to possess a characteristic profile of mycolic acid composition, and they were shown to be classified approximately into at least four groups: (1) C28 to C48 (average carbon numbers C33 ∼ 38) mostly saturated for Nocardia erythropolis and several ‘Mycobacterium rhodochrous complex’; (2) C34 to C50 (average C43 ∼ 34) monoenoic and dienoic for N. rubra, N. corallina and N. lutea; (3) C44 to C58 (average C51 ∼ 52) monoenoic to tetraenoic for N. asteroides and ‘true’ nocardiae; (4) C56 to C68 (average C62 ∼ 64) monoenoic to pentaenoic for N. polychromogenes and Gordona bronchialis. The results indicate that the structural determination of mycolic acids by gas chromatography mass spectrometry can be one of the most useful criteria for the chemotaxonomy of Nocardia and related bacteria.
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  • 59
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    Journal of High Resolution Chromatography 2 (1979), S. 487-496 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Comparison of FID, ECD, FPD for detection limit. linearity, peak shape etc. ; Practical results for pesticide residue and coal hydrogenation products given ; Concentration dependent detectors in capillary GC interesting, when optimized ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A comparison of the characteristics and Performance of the flame ionization, electron capture, and flame photometric detectors with capillary columns is described. Factors which may affect the limits of detection, linearity, chromatographic peak shape, and other detector performance characteristics are discussed and compared with the results of a model derived for the behavior of concentration and mass flow-rate dependent chromatographic detectors used with capillary GC systems. Examples are given of highly complex and labile mixtures such as pesticide residues and products from coal hydrogenation.
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  • 60
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    Journal of Raman Spectroscopy 5 (1976), S. 219-241 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A pulsed-laser Raman spectroscopy system using a doubled Nd: YAG laser is described. Comparisons between spectra recorded using the repetitive mode (low peak power and high duty cycle) with those recorded using the burst mode (high peak power and low duty cycle) are presented showing the degree of discrimination against fluorescence and stray ambient light obtained with a gated detection system. Spectra of nylon, acrylic, benzene with acridine orange, doped SrF2 crystal, and various forms of aluminum oxide and hydroxide are presented. The spectra suggest that the burst mode consistently gives, in all cases, at least a slightly improved Raman-signal-to-noise ratio with some cases showing specular improvement. The results of a preliminary analysis of the Raman spectra of benzene liquid and vapor adsorbed on aluminum oxide/hydroxide powder using the gated burst mode are also presented. Although these spectra were found to differ from that of the liquid, some tentative line identities are offered.
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  • 61
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    Biological Mass Spectrometry 12 (1977), S. 119-124 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fragmentation behavious under electron of di- and tri-peptide analogues containing amino acid (aa) and aminomethylphosphonic acid (ap) groups are described. Successive fragmentations of the molecular ions provided a convenient method for the sequence determination of peptides containing aa and ap units.
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  • 62
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    Biological Mass Spectrometry 6 (1979), S. 205-207 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Field desorption mass spectrometry was applied to the screening of aquatic environments for herbicides. The standard field desorption mass spectra of these compounds are also presented. The spectra of standard herbicides showed molecular and isotope ions, but fragment ions were not observed. The molecular ion was observed as the base peak. The spectra of the extracts of water showed positive responses at m/z 257 and m/z 344 corresponding to molecular ions of benthiocarb and oxadiazon. These herbicides were simultaneously confirmed when present in mixtures.
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  • 63
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High-resolution mass spectra of anti- and syn-acylferrocene oximes were examined at various ionizing voltages and fragmentation patterns of the oximes are presented. Significant differences between the anti- and syn-isomers were found in the fragmentation behaviour of the low voltage (15 to 20 eV) spectrum of formylferrocene oxime.
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  • 64
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    Biological Mass Spectrometry 13 (1978), S. 113-118 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The behaviour under electron impact of methyl 2,3-dideoxy-2,3-epithio-α-D-allopyranoside, methyl 2,3-dideoxy-2,3-epithio-β-D-allofuranoside, 1,6-anhydro-2,3-dideoxy-2,3-epithio-β-D-allopyranose, 1,6-anhydro-2,3-dideoxy-2,3-epithio-β-D-allofuranose and 2,3-dideoxy-2,3-epithio-β-D-allofuranose has been examined. The fragmentation pathways have been deduced by determination of the fragment ions elemental compositions, assignment of the metastable ions fröm the mass number shifts resulting from deuterium replacement, and by the comparison with an epoxide analogue.
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  • 65
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    Organic Magnetic Resonance 12 (1979), S. 254-256 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The carbon chemical shifts of several series of α-haloketones have been measured. Whereas the carbon carrying the halogens shows a regular downfield shift with increasing electronegativity of the substituents, the adjacent carbonyl carbon is shifted upfield by chlorine, bromine and iodine, and is little affected by fluorine substitution. The conformational implications of these results are discussed.
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  • 66
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    Biological Mass Spectrometry 14 (1979), S. 405-413 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass fragmentation of twelve new 2- and 4-alkylthio substituted derivatives of uracils is discussed and fragmentation pathways, elucidation of which was assisted by accurate mass measurements and metastable transitions, are proposed. It has been found that the position of uracil ring thiation may be deduced on the basis of mass spectral fragmentation patterns.
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  • 67
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    Biological Mass Spectrometry 6 (1972), S. 559-563 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectral fragmentations of a number of steroidal 3,5- and 4,5-diols and some derivatives have been examined using high resolution mass spectrometry and deuterium labelling. Although the 3,5- and 4,5-diols have very similar mass spectra those of the derived ketols are quite characteristic. A pathway for the formation of the important m/e 332 ion in the mass spectrum of cholestan-4β,5α-diol has been postulated.
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  • 68
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    Organic Magnetic Resonance 4 (1972), S. 463-467 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Examination of PMR spectra of the four 3-dimethylamino-trans-2-decalols and the corresponding quaternary ammonium iodides allows the suggestion to be made that the ordinary double chair conformation usually admitted for trans-decalin is disurbed in the above compounds, especially when the amino and hydroxy groups are (a, e); truer conformations would, in fact, be better represented as ‘flattened chair’ in the case of the dimethylamino compound and ‘twist chair’ in the case of the quaternary ammonium salt.
    Notes: L'examen des spectres de RMN des quatre diméthylamino-3-décalols-2-trans et des iodures d'ammonium quaternaires correspondants permet d'envisager pour ces composés une déformation de l'un des cycles de la décaline trans habituellement double chaise.Cette déformation est apparente specialement dans le cas de l'isomère cis à groupements hydroxyle equatorial et diméthylamino axcial, pour lequel on propose une conformation ‘chaise aplatie'. Le passage à l'ammonium quaternaire accentue entre deformation jusqu’à la conformation chaise-bateau ou préférentiellement chaise croisée.
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  • 69
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    Organic Magnetic Resonance 6 (1974), S. 497-498 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The four isomeric 3-dimethylamino-trans-2-decalols-1,1,4,4-d4 have been synthesised. Examination of PMR spectra of these compounds allows us to confirm the ‘flattened-chair’ conformation for the cis N(CH3)2a OHe isomer, whereas the remaining three conserve the double chair conformation. The same type of flattening is also observed in the case of the diaxial quaternary ammonium salt and is even more marked in the cis N(CH3)3a OHe isomer resulting in a ‘twist-chair’ conformation.
    Notes: Les quatre tétradeutério-1,1,4,4 diméthylamino-3 décalols-2 trans ont été synthétisés. L'examen des spectres de RMN de ces composés permet de confirmer la conformation ‘chaise aplatie’ de l'isomère cis à groupement diméthylamino axial et hydroxyle équatorial, tandis que les autres d'ammonium quaternaires on note également une déformation dans le cas du composé diaxial, cette déformation est accentuée dans l'iodure d'ammonium quaternaire cis N(CH3)3a OHe, conduisant à la conformation ‘chaise croisée’.
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  • 70
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    X-Ray Spectrometry 8 (1979), S. 102-103 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Odd-shaped pieces of material were analysed by first setting them in a thermoplastic resin containing copper or iron powder. In subsequent measurements the copper or iron was used as monitor to correct the measurements on the sample. Corrections for coincidence losses of counts were found to be very important when applying this method.
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  • 71
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    X-Ray Spectrometry 7 (1978), S. 33-37 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The Thallium Acid Phthalate (TIAP) analysing crystal is compared with KAP, RBAP and pentaerythritol (PE) crystal for the determination of light elements. Peak and background intensities are compared for various crystal-collimator combinations. It is shown that TIAP is a very useful crystal to cover the range of elements F to Si.
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  • 72
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    Organic Magnetic Resonance 8 (1976), S. 532-535 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The longitudinal 13C spin relaxation times T1 and the 13C{1H} nuclear Overhauser enhancement were measured in a concentrated aqueous solution of the basic pancreatic trypsin inhibitor. The correlation time for overall rotational motions of the basic pancreatic trypsin inhibitor molecules was found to be τR ≈ 2 × 10-8 s. In connection with previous 1H n.m.r. studies of intramolecular motions of the aromatics, we were particularly interested in the correlation times τG for intramolecular segmental motions of the aromatic rings. The present experiments revealed no manifestation of intramolecular motions of the aromatics, indicating that τG ≫ 2 × 10-8 s for the aromatic ring carbon atoms. On the other hand, rapid segmental motions were evidenced for the peripheral carbon atoms of aliphatic amino acid sidechains. Comparison of the 1H and 13C n.m.r. data on the basic pancreatic trypsin inhibitor indicates that the time scale of high resolution 1H n.m.r. at high fields may in many instances be more appropriate for studies of the molecular dynamics in globular proteins than the time scale of spin relaxation measurements.
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  • 73
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    Biological Mass Spectrometry 7 (1973), S. 1253-1265 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectra of simple alkyl-N-phenylcarbamates are presented. The wellknown skeletal rearrangement of ethyl-N-phenylcarbamate giving rise to the [C6H5NHCH2]+ ion2 also plays an important role in the fragmentation of the methyl, propyl and butyl homologues. The mechanism of its formation postulated by Lewis in 1964 has been shown to be incorrect with the aid of deuterium and 13C-labelling.
    Notes: Die Massenspektren einfacher Alkyl-N-Phenylcarbamate werden beschrieben, Die bekannte Skelettumlagerung, die beim Aethyl-N-phenylcarbamat zu einem [C6H5NHCH2]+-Ion2 führt, wird auch bei den Methyl-, Propyl- und Butylhomologen beobachtet. Anhand deuterium- und 13C-markierter Verbindungen wird gezeigt, daß der von Lewis 1964 formulierte Umlagerungs- mechanismus die tatsächlichen Verhältnisse nicht richtig wiederzugeben vermag.
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  • 74
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    Biological Mass Spectrometry 5 (1971), S. 743-750 
    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 4-hydroxy-6-methyl-2-pyridone, its N-methyl and N-phenyl derivatives, and also their 4-O-acetyl and 3-C-acyl derivatives have been studied. The proposed fragmentation pathways were supported by comparison of the mass spectra and in some cases by the spectra of deutero analogues. A strong N-phenyl group effect has been found, which in the case of N-phenyl-4-hydroxy- and N-phenyl-4-acetoxy-6-methyl-2-pyridones promotes the formation of the stable [M - H]+ and [M - CH3CO]+ ions respectively. These ions are not characteristic of the N - H and N - Me analogues.
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  • 75
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The configuration at C-2 and C-4 in the molecules of 2-methyl- and 1,2-dimethyl-4-vinylethinyl(n-butyl)-4-hydroxyperhydroquinolines was determined by mass spectrometry. The principal conclusions concerning the stereochemistry were made on the basis of differences in the values of the I[M-15]+/I[M]+·, I[M-17]+/I[M]+·, I[M-43]+/I[M]+· and I[M-57]+/I[M]+· ratios in the mass spectra of the epimeric vinylethinylic alcohols, and of the I[M-15]+/I[M]+· and I[M-15]+/I[M]+· ratios in the case of the n-butylic alcohols.
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  • 76
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    Biological Mass Spectrometry 7 (1973), S. 1313-1320 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: With the aid of the mass spectra of 14,14-d2 analogues the majority of the m/e 98 ions in the spectrum of allomatridine were shown to contain ring D, whereas in the case of matridine and isosophoridan the m/e 98 ions mainly include rings A or B. The m/e 84 ion results mostly from a charge localisation on ring D for allomatridine and isosophoridan, while in the case of matridine it may arise due to charge localisation on ring D accompanied by migration of the 14-H atom from the charged fragment, as well as on rings A or B with a hydrogen atom migrating to the charged species.
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  • 77
    ISSN: 0935-6304
    Keywords: Gas chromatography / electron impact (EI) and chemical ionization (CI) / mass spectrometry ; N,N-diethyl-m-toluamide ; Characterization of urinary metabolites of DEET in man ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies of the pharmacology and toxicology of the popular insect repellant, N,N-diethyl-m-toluamide (DEET), have largely been done in animal models using radioactive tracing without the structural elucidation of its metabolites.This paper describes a high resolution gas chromatography/mass spectrometry (GC/MS) technique and reports the results of the preliminary characterization of the metabolites of DEET in the urine of a 30-year-old man who had been exposed to DEET contained in a commercial product. The metabolites were extracted and separated with an OV-101 glass capillary column, 30 m × 0.3 mm, and mass spectrometric elucidations were carried out with both Electron Impact (EI) and Chemical Ionization-Methane (MCI) modes.Oxidation of the benzylic moiety and hydroxylation of the sidechain of DEET molecules appeared to be the predominate routes of metabolism in man. The artifacts were also proposed.
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    Journal of High Resolution Chromatography 2 (1979), S. 189-190 
    ISSN: 0935-6304
    Keywords: Gas Chromatography ; Capillary, glass ; Tin-selective FPD ; Triphenyltin hydroxide ; TPTH ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new method for the determination of triphenyltin hydroxide using capillary column gas chromatography with a tin-selective flame photometric detector has been developed. Triphenyltin hydroxide and its potential metabolites are converted to methyl derivatives and separated on glass capillary columns coated with OV-101. Derivatization of triphenyltin hydroxide, triphenyltin chloride, diphenyltin dichloride, phenyltin trichloride, and bis-triphenyltin oxide is nearly quantitative with a minimum of redistribution products. The selectivity of the flame photometric detector is cearly demonstrated by the comparison of chromatographic profiles obtained from using both the flame photometric and flame ionization detectors.The use of this chromatographic system in the analysis of triphenyltin hydroxide in a fortified water sample demonstrates the potential use of this system in organotin residue chemistry.
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    Organic Magnetic Resonance 9 (1977), S. 155-156 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituent effects upon 3J(FF) are demonstrated to be additive, and a previous analysis of 4J(FF) and 5J(FF) in polysubstituted fluorobenzenes is updated.
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  • 80
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: There has been much interest recently in both electron-impact induced remote functional group interaction and migration of the trimethylsilyl moiety. The title compound illustrates these phenomena, showing an important (at 12 eV) peak at mass 179 which incorporates both functionalities. Moreover, the cis and trans stereoisomers show a marked difference in the relative intensity (Rel. int.) of this peak, indicating that stereochemical integrity is maintained after initial ionization. The origin of all characteristic peaks has been demonstrated using specifically labeled isotopic analogs, high resolution measurements and metastable defocusing.
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  • 81
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The [C6H6O]+· ion from C6H5OC4H9 is structurally similar to the molecular ion from phenol as demonstrated by 13C labeling.
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  • 82
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    Biological Mass Spectrometry 14 (1979), S. 596-600 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A variety of thiol and thion esters, including acetates and benzoates with n-butyl and β-phenethyl alkyl groups, have been studied by electron impact mass spectrometry. Several rearrangement ions were documented and their persistence in low voltage and field ion spectra demonstrated. Among the significant ions found in the rich thion spectra, the most general requires O to S rearrangement of the alkyl group and subsequent cleavage to yield acyl ions (CH3CO or PhCO). This process is more important in longer chain compounds than in the methyl and ethyl homologues studied previously.
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  • 83
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    Biological Mass Spectrometry 1 (1974), S. 154-155 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first application of field desorption mass spectrometry to the analysis of intact diacyl glycerophosphorylcholines (lecithins) has led to the detection of prominent molecular ions. This technique enables positive identification of the components of a mixture of phosphatidylcholines, which will provide valuable information on the phospholipid composition of biological fluids.
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  • 84
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    Biological Mass Spectrometry 1 (1974), S. 425-426 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition of a macrocyclic ligand, such as a crown ether or cryptate, to the solution of an organic compound containing alkali metal ions prior to field desorption mass spectral analysis, has been shown to result in a reproducible, smooth field desorption process at low anode temperature. Crystalline dibenzo-18-crown-6 ether complexes of NaI and KI give field desorption spectra in which free and complexed ligands are of comparable intensity. Cryptate complexes retain the metal ion even more strongly, as illustrated by the fact that the complex of LiCl with [2.1.1]-cryptate yields almost exclusively the complexed lithium peak on field desorption. Alkali metal salts with organic anions also desorb more smoothly after complexation, although in the case of simple carboxylates the anion is found only in a cluster peak.
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  • 85
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Field desorption mass spectra have been obtained for dipalmitoylphosphatidyl choline-d0, -d4 and -d9. The two latter compounds were synthesized from dimethylene-d4 choline bromide and trimethyl-d9 choline bromide, respectively. Comparison was made of spectra of these three compounds obtained at different field anode temperatures in order to establish the composition of the major cleavage, rearrangement, and association ions. At low anode heating currents (≤ 20 mA) the most intense peak is [M + 1]+ which accounts for c. one-third of the total ionization. At higher temperatures various fragmentation processes, some of which are without analogy in electron impact mass spectrometry, become more important. The presence of an intermolecular methyl transfer process has been confirmed.
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  • 86
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    Biological Mass Spectrometry 10 (1975), S. 1147-1151 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Choline chloride, bromide and iodide all contain a peak at m/e 118 [M + 14] in their field desorption mass spectra. Comparison with choline(methyl-d9) chloride demonstrates that this peak arises from an intermolecular transfer of a methyl group. Partial exchange of hydroxyl hydrogen on choline chloride does not displace the m/e 118 peak, suggesting that this hydrogen is lost during methyl transfer. The structure of the [M + 14] species should then correspond to choline methyl ether.
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  • 87
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    Biological Mass Spectrometry 2 (1975), S. 63-64 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 88
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    Biological Mass Spectrometry 8 (1974), S. 279-287 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relative rates of the McLafferty rearrangement in n-butyl acetate and several related molecules have been examined over the time range 10-11 to 10-5 s by means of a field ionization mass spectrometric technique. It was found that the introduction of a substituent group of low ionization potential (phenyl, dimethylamino) at sites remote from the ester oxygens reduces the rate of the McLafferty rearrangement and that the rate becomes lower as the substituent is moved further away from the ester group. The results suggest that for the cases examined the charge on the molecular ion may be localized on the functional group of lowest ionization potential.
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  • 89
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    Biological Mass Spectrometry 2 (1975), S. 204-205 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A N-dealkylated metabolite, 1-phenylcyclohexylamine, was detected in a urine sample of a patient who had ingested phencyclidine. The identification was facilitated by a feeding experiment using a mouse administered a 1:1 mixture of unlabeled and phenyl-d5-labeled drug. A control experiment was also performed in which a mouse was fed only the unlabeled drug. Two hydroxylated metabolities were also identified in human urine samples. One of the hydroxylated metabolites has a hydroxy group located at the piperidine moiety of phencyclidine while the other has the hydroxy group located at the cyclohexane ring of the drug. It was also shown that 1-phenyl-cyclohexene detected in the human samples, was an artifact which arose from pyrolysis of phencyclidine during gas chromatography.
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  • 90
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dihydrodiols are derived from intermediary arene oxides during the metabolism of polycyclic aromatic hydrocarbons. In this study, the mass spectra of the trimethylsilyl ether derivatives obtained from the 5,6-dihydrodiol and 8,9-dihydrodiol of 7,12-dimethylbenz[a]anthracene were compared. The mass spectral fragmentation patterns indicate some key features in distinguishing a K-region dihydrodiol from its non K-region isomer. The 8,9-dihydrodiol, a non K-region metabolite, exhibits a greater tendency to undergo a ringcontraction fragmentation process while the K-region 5,6-dihydrodiol participates preferably in other fragmentation pathways. The data presented in this report will be useful in characterizing K-region and non K-region metabolic epoxidation of polycyclic aromatic hydrocarbons.
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  • 91
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    Biological Mass Spectrometry 11 (1976), S. 375-382 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The elimination of small neutral fragments from acetyl-, formyl- and ethoxycarbonyl- phenylhydrazines with formation of [C6H8N2]+⋅ ions has been studied. Evidence is obtained from deuterium labelling and from metastable peak intensity ratios, to show that ketene loss from both acetylphenylhydrazines is accompanied (or preceded) by hydrogen transfer to the acylated nitrogen atom to give ions structurally analogous to the phenylhydrazine molecular ion. The decomposing [C6H8N2]+⋅ ions formed from formyl- and ethoxycarbonylphenylhydrazines are also suggested to have a phenylhydrazine-like structure. In the molecular ion of phenylhydrazine interchange occurs between the two ortho hydrogen atoms and two of the three hydrazine hydrogens prior to decomposition; labelling data suggest that the N-1 hydrogen does not participate in the interchange process.
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  • 92
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    Biological Mass Spectrometry 11 (1976), S. 394-397 
    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- and S-phenylbenzohydrazonates and the isomeric N, N-diphenylbenzohydrazides have been examined. The benzohydrazonates decompose by expulsion of a phenoxy (thiophenoxy) radical, or by elimination of phenol (thiophenol); the latter is a new example of the mass spectral retro 1, 3-dipolar cycloaddition reaction. There are no indications of a mass spectral Chapman rearrangement in these compounds, while evidence is adduced for a mass spectral retro Chapman rearrangement in the spectrum of N, N-diphenylthiobenzohydrazide.
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  • 93
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    Biological Mass Spectrometry 13 (1978), S. 338-340 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complete isomerization of the molecular ion of r-2-deuterio-2, cis-4,cis-6-trimethyl-1,3,5-trithian into equal proportions of 3, 5- and 6-d1-3,5,6-trimethyl-1,2,4-trithian molecular ions adequately accounts for all major fragmentations of the former. These fragmentations are losses of C4H8, C2H4S, S2H·, C4H8S and C2H4S2. Similar rearrangements are proposed for other 1,3,5-trithans and 1,3-dithians.
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  • 94
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    Biological Mass Spectrometry 9 (1974), S. 181-188 
    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 di-, tri- and tetraaryl substituted 1,3,4-thiadiazolines have been examined. They are characterized by thiadiazolium ions, formed by elimination of a C-5 substituent, by ions formed through elimination of C6H5S· radicals arising by transannular phenyl migration and by ions generated via elimination of thiocarbonyl neutrals in retro-1,3-dipolar cycloaddition reactions. The influence of the stability of the dipolarophile on the latter reaction is discussed and the fragmentation reactions of thiadiazolines and oxadiazolines are compared.
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  • 95
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: From collisional activation data it is concluded that the non-decomposing [MH—H2O]+ ions from both cis-and trans-1,2-cyclohexanediol possess the structure of protonated cyclopentanecarboxaldehyde. The mechanism of this process as well as alternatives are discussed.
    Notes: Stoßaktivierungsspektren legen den Schluß nahe, daß die H2O-Abspaltung aus protoniertem cis- und trans-1,2-Cyclohexandiol zum protonierten Cyclopentylcarbaldehyd führt. Der Mechanismus dieser und alternativer Reaktionen wird diskutiert.
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  • 96
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The consecutive dehydration of protonated molecules [MH]+ of 1,2- and 1,3-cyclohexanediols (cis and trans isomers) by loss of two H2O molecules has been investigated. Analysis of 2H labelled compounds showed that loss of the first H2O molecule represents a simple heterolysis, i.e. a dissociation without exchange of hydrogens between O - H and C - H bonds. Subsequent elimination of the second H2O molecule in the process [MH-H2O]+→[MH-2H2O]+ followed several competing paths. The two major ones corresponded formally (with reference to an intact 6-ring skeleton) to 1,3- and 1,4-eliminations; in comparison, the alternative 1,2-elimination is only a minor route at most. At least for the 1,3-elimination, water loss from the [MH-H2O]+ ions is not direct, but is associated with skeletal rearrangement, most probably of the Wagner-Meerwein-type, effecting contraction of the 6- to a 5-membered ring.
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  • 97
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The introduction of a benzene ring between the hydroxyl and carbomethoxyl groups of long chain aliphatic hydroxy esters results in a steric hindrance which restrains the interactions between the functional groups and the resulting fragmentations. The study of a series of methyl p-(hydroxyalky) benzoates shows that the importance of these interactions decreases considerably state with (9 + φ)links, or less to the benefit of those fragmentations which do not require such interactions. It is further shown that the specific transfer of a benzylic hydrogen atom to the carbomethoxyl group involves transfer via the hydroxyl group.
    Notes: L'introduction d'un noyau benzénique entre les groupes hydroxyle et carbométhoxyle d'hydroxyesters aliphatiques à longue chaîne introduit une contrainte stérique qui s'oppose aux interactions entre les deux groupes fonctionnels et aux fragmentations qui en résultent. L'étude d'une série de p-(hydroxyalkyl)benzoates de méthyle montre que l'importance de ces interactions diminue considérablement lorsque le transfert de l'hydrogène hydroxylique sur le groupe carbométhoxyle nécessite un état de transition de (9+ φ) chaînons, ou moins, au profit des fragmentations qui ne résultent pas de ces interactions. Il est montré qu'un transfert spécifique d'un hydrogène benzylique sur le groupe carbométhoxyle s'opère via le groupe hydroxyle qui sert de relais.
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  • 98
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the basis of the CNDO/2 method paramagnetic screening constants of the central atom of tetrasubstituted silicon compounds of the type Me4-nSiXn (X = F, OMe, NMe2, C1) are calculated, both with and without ΔE approximation. The results are compared with the experimental 29Si n.m.r. chemical shifts. The ‘averaged excitation energies’ ΔE obtained from the comparison of calculated values depend on the charge of the central atom and cannot be considered to be constant for quantitative studies.
    Notes: Auf der Basis des CNDO/2-Verfahrens werden paramagnetische Abschirmungskonstanten für das Zentralatom tetrasubstituierter Siliciumverbindungen Me4-nSiXn (X = F, OMe, NMe2, C1) mit und ohne ΔE-Näherung berechnet und mit den experimentellen 29Si-NMR-chemischen Verschiebungen verglichen. Die aus dem Vergleich der berechneten Werte erhaltenen ‘mittleren Anregungsenergien’ ΔE sind von der Ladung am Zentralatom abhängig und können für quantitative Betrachtungen nicht als konstant angesehen werden.
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  • 99
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    Biological Mass Spectrometry 9 (1974), S. 594-600 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mass spectra of closo-phosphorimide, P4(NCH3)6, closo-thiophorimides, P4(NCH3)6Sn with n ranging from 1 to 4 and closo-arsenimide As4(NCH3)6 were obtained, and systematic trends were recognised in their fragmentation patterns. The introduction of thiophosphoryl groups gives a superposition of the fragmentation modes indentified with P4(NCH3)6 and P4(NCH3)6Sn. The fragmentation paths are completely different from those of adamantane and its derivatives or hexamethylene teramimne.
    Notes: Les spectres de masse du closo phosphorimide P4(NCH3)6Sn, où n = 1 à 4, et du closo arsenimide As4(NCH3)6 ont été et des schémas de fragmentations systématiques ont été dégagés, L'introduction des groupes thiophosphoryles se traduit par une superposition des deux types de fragmentations identifiées pour P4(NCH3)6 P4- dérivés ou de l'hexaméthylène tétramine.
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  • 100
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    Biological Mass Spectrometry 6 (1979), S. 173-178 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A study of the effect of crystal size on the bioavailability of benoxaprofen, 2-[4-chlorophenyl]-α-methyl-5-benzoxazoleacetic acid, in man is reported. The technique utilized comparison of either the plasma concentrations or urine levels, resulting from administration of deuterium labeled (2H7) drug in solution coadministered with a test capsule formulation. Drug concentrations were determined by gas chromatography, and the ratio of labeled to unlabeled drug was obtained by gas chromatography mass spectrometry. Measurements following coadministration of labeled and unlabeled drug in solution established the absence of an isotope effect due to the presence of deuterium. The dry formulations consisted of either a 3.17-100 micron fraction (mean = 18.5 microns) or a 32-1000 micron fraction (mean = 610 microns) formulated with starch powder. The results in three subjects indicate an almost complete availability (0.95-0.98) of the small crystals as measured by comparison of either area under the plasma level curves or urine excretion (0.94-0.97) of labeled versus unlabeled drug measured to 168 hours. The larger crystals exhibited a lower availability as shown by plasma levels (0.41-0.46) or urine recovery (0.39-0.43). A higher dose of the large crystal formulation resulted in decreased relative availability with a fourfold dose dropping availability to 0.22 in a single subject.
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