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  • Organic Chemistry  (3)
  • Polymer and Materials Science  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    A proposed solution for the determination of the ionization constants of sets of ionizing groups in proteins (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 891-902 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A mixture of acids with known pK′ and in a known concentration was dissolved to simulate the ionic character of hemoglobin. The titration curves of the mixture were obtained in water and 3.6 M KCl at 20°C. These curves were subjected to analysis by a reiterative curve-fitting procedure to determine if one could evaluate both the group ionization constants and the numbers of groups. This approach was successful in that the calculated parameters were within the experimental error encountered in obtaining these constants on each of the model compounds. However, analysis for the electrostatic interaction parameter w indicated that there was a possible effect on the ionization of formic acid, pyridine, imidazole, and the α-amino group of glycylglycine in water and on imidazole and the α-amino group of glycylglycine in 3.6 M KCl.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130505
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Complex formation between 1,3,5-trinitrobenzene and 1,8-diazabicyclo-[5,4,0]-undec-7-ene (1988)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 1 (1988), S. 351-357 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The title reaction is an instance of a simple nucleophilic attack of neutral nitrogen on aromatic sp2 carbon. The kinetic data (obtained in dimethyl sulphoxide) are compared to the results reported by the literature for the same reaction of aliphatic amines. Some possible interactions (substrate/nucleophile, substrate/salt) preceding the attack of the nucleophile are discussed.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610010605
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Catalysis in nucleophilic aromatic substitution reactions. A reinvestigation of the reaction between 1-fluoro-2,4-dinitrobenzene and n-butylamine (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 429-434 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reaction between 1-fluoro-2,4-dinitrobenzene and n-butylamine in toluene shows a two-step plot of kobs, values vs the initial values of the concentration of the amine. The usual base-catalysis mechanism for HF elimination from the zwitterionic intermediate hardly explains this kinetic behaviour and the kinetic effect of addition of salts (and of 2-hydroxypyridine) to the reaction mixtures at different initial values of the concentration of n-butylamine. In contrast, the kinetic behaviours are easily explained by the presence of substrate-amine (or catalyst) interactions on the pathway of the substitution reaction.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050707
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Self-catalysis and molecular complexes in aromatic nucleophilic substitution reactions: Reaction between 1,3,5-trinitrobenzene and 1,8-diazabicyclo [5.4.0] undec-7-ene in toluene (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 653-659 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The formation of a σ-like complex by reaction between 1,3,5-trinitrobenzene and 1,8-diazabicyclo [5.4.0]-undec-7-ene was investigated in toluene at various temperatures. The kinetic data showed autocatalytic behaviour. Inspection of the reaction mixtures at zero reaction time indicated the presence of an equilibrium preceding the attack of the nucleophile, affording a molecular complex (substrate-nucleophile) which is responsible for the observed kinetic features. The present and the previous data led to the conclusion that the catalytic behaviours usually observed in SNAr reactions (in apolar solvents with amines as nucleophiles) are better explained by the presence of substrate-catalyst interactions than by catalysis on departure of the proton and leaving group from the zwitterionic intermediate.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020808
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    Paper (German National Licenses)
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