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  • 1
    Electronic Resource
    Electronic Resource
    N.m.r. studies of the keto-enol tautomerism of acylthioacetamidesChelates of β-dicarbonyl compounds and their derivatives, Part 51. (1977)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 10 (1977), S. 151-156 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acetylthioacetamides exist as different keto and enol isomers in chloroform solutions. The keto form with intramolecular hydrogen bonding between the NH and the carbonyl group is the dominant keto isomer. On the other hand the enol forms with intramolecular hydrogen bonding between the OH and the thioketo group are the dominant enol isomers in the temperature range 60°C to -60°C. The thermodynamic data of the keto-enol equilibria were obtained by measuring the intensities of appropriate high resolution proton signals as a function of temperature. At low temperatures all lines characteristic of the enol forms are doubled in the N-phenyl-substituted derivatives because the rotation of the NH—C6H5 group around the C—N bond becomes slow and the chemical shifts characteristic of the E and Z isomers are different. We estimated approximate thermodynamic data of the E/Z equilibrium in some of the compounds. The changes of the line shape as well as the chemical shifts as a function of temperature indicate the presence of various additional exchange processes. In order to obtain further information we performed curve fittings of the chemical shifts of one acetylthioacetanilide and of a series of monothio-β-diketones (studied in another paper) assuming a fast two site exchange process. On the basis of the results obtained a reaction scheme for N-substituted acylthioacetanilides in solution is proposed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270100135
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  • 2
    Electronic Resource
    Electronic Resource
    Hydrolysis of γ-[1-methyl-5-bis(β-chloroethyl) amino-2-benzimidazolyl]butyric acid. Studied by 1H NMR (1982)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 19 (1982), S. 15-20 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High resolution 1H NMR is applied to the study of hydrolysis and equilibria in the complex system of γ-[1-methyl-5-bis(β-chloroethyl)amino-2-benzimidazolyl]butyric acid and D2O. Kinetic data for the individual hydrolytic steps are obtained for the first time. The hydrolytic reactions are pseudo first order. The differences in the activation energies of the two hydrolysis steps are accounted for by different intermediates. Furthermore, equilibrium constants for the deuteration of the N mustard group in the individual products are quantitatively estimated. They show an increase of the basicity of N mustard with hydrolysis. The applicability of the 1H NMR method is restricted to a pD range of 0.5-4.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270190105
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  • 3
    Electronic Resource
    Electronic Resource
    Zur Friedel-Crafts-Acylierung von 8-Hydroxychinolin (1981)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 323 (1981), S. 521-524 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Friedel-Crafts-Acylation of 8-Hydroxyquinoline
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19813230321
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  • 4
    Electronic Resource
    Electronic Resource
    Chelate von β-Diketonderivaten. XIIVorbericht: Z. anorg. allg. Chem. 359, 333 (1968).. Thermodynamische Stabilität von Protonen- und Metallchelaten isomerer β-Thioxoketone (1969)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 364 (1969), S. 153-160 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The stability constants for metal and proton chelates of some β-thioxoketones were determined potentiometrically in dioxane-water mixture, and the influence of substituents on chelate stability was studied for zinc compounds as a model. Additional information about the stability of the proton chelates could be received by NMR spectroscopic work from the chemical shifts of methine and hydroxyl protons. The dependence of complex stability on the nature of central ions is discussed by means of stability data for metal chelates of thiodibenzoyl-methane.
    Notes: Die Stabilitätskonstanten der Metall- und Protonenchelate einer Reihe von β-Thioxoketonen wurden auf potentiometrischem Wege in Dioxan-Wasser-Mischung bestimmt und am Beispiel der Zinkchelate der Einfluß der Substituenten auf die Chelatstabilität studiert. Weitere Aussagen über die Stabilität der Protonenchelate konnten durch NMR-spektroskopische Untersuchungen aus den chemischen Verschiebungen für Methin- und Hydroxylprotonen erhalten werden. Die Abhängigkeit der Komplexstabilität vom Charakter des Zentralatoms wurde an Hand von Stabilitätskonstanten für Metallchelate des Thiodibenzoylmethans diskutiert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19693640306
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesen in der Isochinolinreihe. III. Die Stereochemie der Addition von Methylvinylketon an 1-Benzyl-2-acetyl-3-carbomethoxy-4-piperidon: Ein Beitrag zur Stereochemie der MICHAEL-AdditionDr.-Ing. Karl Smeykal zum 65. Geburtstag gewidmet (1965)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 29 (1965), S. 142-157 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Die MICHAEL-Addition von Methylvinylketon an 1-Acetyl-2-benzyl-3-carbomethoxy-4-piperidon verläuft vollständig stereoselektiv und liefert in zwei Reaktionsstufen praktisch ausschließlich eines von vier möglichen Enantiomerenpaaren des 1-Benzyl-2-acetyl-6-keto-9-carbomethoxy-10-hydroxy-decahydroisochinolins (IIIa), wie aus der quantitativ gelungenen Trennung der Säure (IIIb) in die optischen Antipoden hervorgeht. Aus der Rotationsdispersion ergibt sich eine cis-Verknüpfung der beiden Ringe, die außerdem chemisch bewiesen wird.Die Reduktion der 6-Ketogruppe nach MEERWEIN-PONNDORF-VERLEY bzw. durch katalytische Hydrierung an RANEY-Nickel führt überwiegend zum entsprechenden axialen Alkohol, während die Reduktion mit Natriumborhydrid ein Gemisch von äquatorialem und axialem Alkohol (etwa 2:1) liefert. Durch Überführung des äquatorialen Alkohols in das Lacton wird bewiesen, daß von den beiden denkbaren cis-Konformationen diejenige mit (in bezug auf den Cyclohexanring) axialer 9-Carboxylgruppe entstanden ist. Das steht auch in Übereinstimmung mit den Verseifungsgeschwindigkeiten von IIIa und anderen Estern dieses Systems und den Ergebnissen der NMR-Spektroskopie.Die Konformation der Benzylgruppe ließ sich mit Hilfe der IR- und der NMR-Spektroskopie ermitteln.Die Ergebnisse erlauben es, die absolute Konfiguration der Verbindung IIIa festzulegen.Die Gründe für den gefundenen sterischen Verlauf der MICHAEL-Addition werden erörtert und einige allgemeinere Folgerungen daraus abgeleitet.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19650290303
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  • 6
    Electronic Resource
    Electronic Resource
    Berichtigung zur Arbeit „Die Stereochemie der Addition von Methylvinylketon…“ (1966)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 32 (1966), S. 112-112 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19660320116
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  • 7
    Electronic Resource
    Electronic Resource
    199Hg NMR of aqueous solutions of inorganic mercury salts. Chemical shifts of HgCl2 - n with n = 0-4 (1993)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 31 (1993), S. 548-551 
    Details
    ISSN: 0749-1581
    Keywords: Mercury chlorides ; 199Hg chemical shifts ; Chemical exchange ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 119Hg NMR chemical shifts of the stable mercury species HgCln2 - n with n = 0-4 were determined by a least-squares algorithm from 199Hg chemical shifts measured in 50 mM aqueous mercury solution as a function of the chlorine concentration at 25°C. The concentrations of the corresponding mercury species in the solutions necessary in this special procedures were calculated by using published equilibrium constants. The results relative to dimethyl-mercury are -2256 ppm (Hg2+), -1897 ppm (HgCl+), -1560 ppm (HgCl2), -1436 ppm (HgCl3-) and -1152 ppm (HgCl42-) with maximum errors of ±5 ppm.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260310606
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