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  • 1
    Electronic Resource
    Electronic Resource
    Stopped-flow determination of carbon dioxide-diethanolamine reaction mechanism: Kinetics of carbamate formation (1983)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 15 (1983), S. 1147-1160 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction mechanism of carbon dioxide with diethanolamine (DEA) is investigated using the stopped-flow method with optical detection in the ranges of concentration [DEA] = 0.111-8.4 × 10-2M and [CO2] = 2.94-5.6 × 10-3M. The comparison of the fast time-dependent light transmission change of a pH indicator with theoretical simulations of integrated rate equations requires a kinetic model in which a simple carbamate formation takes place simultaneously with hydration reactions, whose contributions are far from being negligible. A first-order reaction relative to DEA is thus found with a rate constant for carbamate formation smaller than usually predicted (110 ± 15M-1s-1 at 25°C). The equilibrium constant for the same reaction is also determined giving pKR = 5.3 at 25°C, in satisfactory agreement with values assumed so far.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550151104
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Transferts Protoniques de Sels d'Ammonium Substitues - VII: Deprotonation de Sels de N-Methylpiperidinium en Solution Aqueuse (1972)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 4 (1972), S. 651-665 
    Details
    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 deprotonation of N-methylpiperidinium salts BHa⊕, observed by means of the coalescence of the N-methyl doublet, is operated either by OH⊖, or by the conjugate base B. The action of OH⊖ is predominant as the steric hindrance increases around Ha and is twice as fast in the axial direction.
    Notes: La déprotonation de sels de N-méthylpipéridinium BHa⊕, observé par la coalescence du doublet N-méthylique en RMN, s'effecute soit par OH⊖ (k1 ∼ 1010 M-1 s-1), soit par la base conjugée B (k2 ∼ 108 M-1 s-1). L'action de OH⊖ est prédominante lorsque croi' l'encombrement stérique autour de Ha, et a lieu 2 fois plus facilement en direction axiale.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270040506
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Le Spectre de L'Alcool Propargylique en Fonction du pH. Un Exemple de Transferts Protoniques Complexes sur un Diacide Organique (1977)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 9 (1977), S. 523-527 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dimethyl sulphoxide (DMSO) is used as a solvent to investigate the kinetic acidity of very weak organic diacids by 1H d.n.m.r. An inspection of the spectrum of propargyl alcohol as a function of the pH allows the assignment of various proton transfer mechanisms:
    Notes: Le diméthylsulfoxyde (DMSO) est utilisé comme solvant pour étudier l'acidité cinétique de très faibles diacides organiques par RMN du proton. Un examen du spectre de l'alcool propargylique en fonction du pH met en évidence less mécanismes de transfer suivants:.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270090907
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Complexation of lanthanide(III) ions with a β-diphosphorylated ligand: Nonamethylimidodiphosphoramide (NIPA). A 1H and 31P NMR study (1987)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 25 (1987), S. 609-618 
    Details
    ISSN: 0749-1581
    Keywords: 1H NMR ; 31P NMR ; complexation ; β-diphosphorylated ligand ; lanthanide(III) ions ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Trivalent lanthanide ions form complexes of different stoichiometries with the bidentate ligand nonamethyl-imidodiphosphoramide (NIPA). Depending on the method of preparation, compounds with two or three NIPA molecules may be obtained, which can be distinguished and characterized on the basis of their NMR spectra. The method of preparation for the tris-chelates and an analysis of the isotropic paramagnetic shifts for these compounds are reported; the results allow the conclusion that the complexes in solution are isostructural along the lanthanide series. The same conclusion is drawn for the bis-chelates. In both cases the contact and pseudo-contact contributions to 31P shifts are important, whereas for the 1H nuclei the dipolar contribution is largely predominant.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260250712
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  • 5
    Electronic Resource
    Electronic Resource
    Stopped-flow investigations of the reaction kinetics of carbon dioxide with some primary and secondary alkanolamines in aqueous solutions (1986)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 18 (1986), S. 445-457 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction kinetics of carbon dioxide with four alkanolamines of industrial importance (MEA, DGA, DEA, and DIPA) have been investigated with the aid of the stopped-flow technique, allowing the determination of rate constants for carbamates formation. The constants obtained for MEA at 20°C and 25°C are in good agreement with recent literature data. The kinetic behavior of DGA was found to be almost identical to that of MEA.The rate constants obtained for DIPA at 25°C (54 M-1 s-1) is half as large as that for DEA (110 M-1 s-1). The former one is satisfactorily compared with the recent values proposed by Blauwhoff et al. Activation energies have also been obtained for DEA (23.2 kJ mol-1) and for DIPA (58.7 kJ mol-1) and their mechanistic implications are discussed in relation with the relevanceof a rate-determining proton transfer step in the process of carbamate formation.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550180404
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    Paper (German National Licenses)
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