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  • Articles: DFG German National Licenses  (3)
  • Morpholine  (2)
  • N-Nitroso-N-methylurea  (1)
  • 1
    ISSN: 1434-4475
    Keywords: Kinetic study ; N-Methylurea ; Nitrosation ; N-Nitroso-N-methylurea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of nitrosation of Methylurea (MU) in aqueous perchloric solution has been studied using two techniques: a dynamic spectrophotometric and a stopped-flow technique. The rate law obtained, whenpH was varied in the range 0.27–3.22, is $$---d[nitrite]/dt = f[MU][nitrite][H^ + ]/(1 + g/[H^ + ])$$ where [MU] and [nitrite] represent stoichiometric concentrations. At 288.0 K and μ=1.0M,f=(15.6±0.5)M −2s−1 andg=(1.06±0.08) 10−3 M. This rate law becomes independent of the acidity of the solution when this is increased ([ClO4H])〉1.00M). These results together with the activation of the nitrosation rate by the ionic strength and the negative value of the activation entropy shown that only the NO2H2 + or NO+ is the effective carrier for the nitrosation. Comparisons with the nitrosation of dimethylamine were also made leading to the conclusion that there is no simple explanation for the fact that the nitrosation via NO2H2 +/NO+ disappears when the nitrosable compound is of increased basicity.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 115 (1984), S. 155-163 
    ISSN: 1434-4475
    Keywords: Acetic acid/acetate ion buffer ; Kinetics of nitrosation ; Medium effect ; Morpholine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Essigsäure/Acetat-Puffer wirkt bei der Nitrosierung von Aminen katalytisch, unter Bedingungen, wo die alleinigen nitrosierenden Agentien N2O3 und NOBr sind; andererseits wird die Nitrosierung durch H2NO 2 + unterbunden. Die kinetischen Charakteristika dieses Phänomens wurden quantitativ analysiert und mit ähnlichen Effekten der LösungsmittelTHF, DMSO und Dioxan verglichen. Die experimentellen Ergebnisse zeigen, daß dieses Verhalten auf einen Mediumeffekt zurückzuführen ist.
    Notes: Abstract Acetic acid/acetate ion buffer acts catalytically upon the nitrosation of amines under conditions in which the only nitrosating agents are N2O3 and NOBr, but inhibits nitrosation by H2NO 2 + . The kinetic characteristics of these phenomena have been analysed quantitatively and compared with similar effects caused by the solventsTHF, DMSO and dioxane. The experimental results show that this behaviour is an effect of the medium.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-4475
    Keywords: Acetate buffer ; Kinetics of nitrosation ; Morpholine ; N-Nitrosomorpholine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wurde die Kinetik der Nitrosierung von Morpholin in Acetat-Puffer untersucht. Unter den gewählten Reaktionsbedingungen ist das effektive Agens N2O3, dessen Bildung von Acetat-Ionen im Einklang mit dem gezeigten Schema gefördert wird: Zwischen Nitrosylacetat und Amin wurde keine Reaktion beobachtet, vermutlich wegen der niederen Konzentration des ersteren. Der vorgeschlagene Mechanismus erklärt, daß keine Katalyse mittels Puffer unter Bedingungen zu beobachten ist, wo der geschwindigkeitsbestimmende Schritt die Reaktion von N2O3 mit dem Amin ist und daß der katalytische Effekt nur dann beobachtet wird, wenn die Bildung des Nitrosierungsagens geschwindigkeitsbestimmend ist. Gleichgewichts- und kinetische Konstanten, die für den Mechanismus von Bedeutung sind, wurden ermittelt.
    Notes: Abstract The kinetics of the nitrosation of morpholine in acetate buffer have been studied. It was found that in the experimental conditions used the effective nitrosating agent is dinitrogen trioxide, whose formation is promoted by the acetate ion in accordance with the scheme: No reaction between nitrosyl acetate and the a mine was observed, probably owing to the low concentration of the former. The proposed mechanism explains the experimental facts that no catalysis by the buffer is observed in conditions in which the rate controlling step is the reaction of N2O3 with the amine, and that the catalytic effect has only been observed when the formation of the nitrosating agent is also rate controlling. Values have been calculated for several equilibrium and kinetic constants involved in the mechanism proposed.
    Type of Medium: Electronic Resource
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