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  • Analytical Chemistry and Spectroscopy  (12)
  • ELISA  (5)
  • 11
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 224-225 
    ISSN: 0030-4921
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: The fast tautomeric equilibrium of (N15)-4-phenylisoxazolin-5-one (2) has been investigated by a study of 2J(N15—H3) coupling. Comparison of the observed values for 2 and for the two fixed forms (N15)-2-methyl-4-phenylisoxazolin-5-one (3) and (N15)-4-phenyl-5-methoxyisoxazol (4) indicates a considerable amount of enolic type structure for 2 in basic media.
    Notizen: La comparasion des constantes de couplage 2J(N15—H3) présentées par la (N15)-4-phénylisoxazoline-5-one (2) et par deux de ses formes fixes, la (N15)-2-méthyl-4-phénylisoxazoline-5-one (3) et le (N15)-4-phényl-5-méthoxyisoxazole (4), indique une participation élevée de structure énolique (et/ou ionique) dans les milieux basiques.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 12
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Low energy collision induced dissociation (CID) spectra indicate that m/z 173 ions formed by the loss of a halogen atom from diethyl chloro- and bromo-succinate under electron impact are mixtures of O-protonated diethyl maleate (〉90%) and fumarate (〈10 %). Hydrogen migration precedes the C-halogen bond cleavage in these cases. The low energy CID spectrum of the m/z 173 [M—I]+ ion obtained from diethyl iodosuccinate shows that only a small fraction of the [M—I]+ ions are the O-protonated species formed by hydrogen migration. The results of this study demonstrate the potential of low energy CID in the determination of structure (including configuration) of gas phase ions.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 13
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 28 (1990), S. S82 
    ISSN: 0749-1581
    Schlagwort(e): 27 Al MAS NMR ; Quadruopolar interaction parameters ; Isotropic chemical shfits ; Spectral simulation ; Al2Ge2O7 ; LaAlGe2O7 ; Pentacoordinated aluminium environment ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Characterization by 27Al MAS NMR of two pentacoordinated environments of aluminium has been carried out in different fields and at different spinning speeds for Al2Ge2O7 and LaAlGe2O7. Complete simulations of the spectra have been performed, including computation of the individual shape and intensity of each spinning side band, which lead to the determination of both the quadrupolar interaction parameters and isotropic chemical shifts, and enable the detection of impurities in the material. The parameters determined are: .
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 14
    ISSN: 0749-1581
    Schlagwort(e): 13C NMR ; 1H NMR ; Ni-Pd-Pt series ; Ni-Pd-Pt substituent effects ; Ni/Pd/Pt-induced paramagnetic shifts ; M(PEt3)2X substituents ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 13C and proton NMR spectra of several arylpalladium and some arylnickel and arylplatinum complexes have been compared. The Ni(PEt3)2X and Pd(PEt3)2X substituents induce a paramagnetic shift of Cipso (of the phenyl ring) which is much larger than that induced by Pt(PEt3)2X. However, there are no significant differences along the Ni/Pd/Pt series for the ortho, meta and para positions. For the six compounds of general formula trans-[ArPdBr(PEt3)2] reported here, the mean Δ(δ)C values induced on the ArH by the introduction of the PdBr(PEt3)2 substituent are found to be 26.9 (Cipso), 7.2 (Cortho), -1.1 (Cmeta), -5.5 (Cpara), -0.03 (Hortho), -0.28 (Hmeta) and -0.38 ppm (Hpara).
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 15
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 24 (1986), S. 284-286 
    ISSN: 0749-1581
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: As an extension of previous work on simple amino acids, deuterium nuclear relaxation rates were used to study the molecular dynamics of γ-2,2-[2H2]aminobutyric acid, d,l-2-[2H1]glutamic acid and d,l-2-[2H1]lysine, and also model compounds 2,2,2-[2H3]acetic acid and 1,1-[2H2]butylamine. This study was carried out in aqueous solution in the pH range ca 0-14. From the observed rotational correlation times and solution viscosities, molecular volumes of various ionic forms were calculated using the Gierer and Wirtz model. The results obtained are in good agreement with conformational changes expected in the pH range investigated.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 16
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 25 (1987), S. 16-20 
    ISSN: 0749-1581
    Schlagwort(e): 13C NMR ; 13C Relaxation Times ; Prototropic equilibria ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Quaternary 13C dipole-dipole spin-lattice relaxation times are used to analyse prototropic equilibria of 2-acetylbenzimidazole (1) and 4-azabenzimidazole in DMSO-d6 solutions. For the first compound, fast exchange between the two chelated structures prevails for 13C relaxation times, whereas proton and 13C chemical shifts characterize a slow exchange. For 4-azabenzimidazole, 13C and 1H spectra do not exhibit absorptions from structures in slow exchange. Analysis of the T1 values of carbons 8 and 9 before and after isotopic exchange of the labile amino hydrogen clearly show that the major component of the equilibrium is the 3H structure.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 17
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 9 (1980), S. 291-296 
    ISSN: 0377-0486
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Raman spectroscopy and microscopy have been used to study some catalysts: Mo supported on alumina. Different Mo species were found, depending upon the amount of molybdenum deposited on the carrier. At low coverages (4% wt MoO3) distorted molybdate tetrahedra were observed. Increasing the surface coverage resulted in the formation of a polymolybdate phase with octahedrally surrounded molybdenum. Additionally, ‘bulk MoO3’ appeared when amounts were above 16% wt MoO3. When the supports were washed during their preparation with aqueous NH4OH and HNO3 solutions, preferential formation of polymolybdate phase was observed. In case of washing with alkaline solution ‘free MoO3’ was also detected. Finally using the Raman microprobe MOLE, a map giving the distribution of the different species at the surface of support was obtained.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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