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  • 1
    Electronic Resource
    Electronic Resource
    Protonation constants of mono-, di- and triethanolamine. Influence of the ionic composition of the medium (1984)
    s.l. : American Chemical Society
    Journal of chemical & engineering data 29 (1984), S. 10-11 
    Details
    ISSN: 1520-5134
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/je00035a004
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of the decomposition of N-chloro-2-(methylamino)ethanol in aqueous solution (1984)
    s.l. : American Chemical Society
    Environmental science & technology 18 (1984), S. 97-100 
    Details
    ISSN: 1520-5851
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/es00120a021
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  • 3
    Electronic Resource
    Electronic Resource
    Microemulsions as a medium in chemical kinetics: the persulfate-iodide reaction (1991)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 95 (1991), S. 6001-6004 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100168a052
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetic studies on the formation ofN-nitroso compounds VII. Nitrosation of morpholine in acetate buffer (1983)
    Springer
    Monatshefte für Chemie 114 (1983), S. 647-660 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01134178
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  • 5
    Electronic Resource
    Electronic Resource
    Kinetische Untersuchungen zur Bildung von N-Nitrosoverbindungen II. Entstehung von N-Nitroso-N-methylharnstoff in wäßriger Perchlorsäurelösung (1979)
    Springer
    Monatshefte für Chemie 110 (1979), S. 1331-1344 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00938290
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  • 6
    Electronic Resource
    Electronic Resource
    Kinetic studies on the formation of N-nitroso compounds XI. Nitrosation of dimethylamine by nitrite esters in aqueous basic media (1986)
    Springer
    Monatshefte für Chemie 117 (1986), S. 335-344 
    Details
    ISSN: 1434-4475
    Keywords: Dimethylamine ; Kinetics of nitrosation ; Nitrite esters ; N-Nitrosodimethylamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die kinetischen Untersuchungen der Nitrosierung von Dimethylamin (DMA) mit Propylnitrit (PrONO) in basischem Medium ergab für den Mechanismus der Bildung von N-Nitrosodimethylamin (NDMA) folgende Geschwindigkeitsgleichung: $$v = d[NDMA]/dt = k_2 [DMA][PrONO]/\left( {1 + \left[ {H^ + } \right]/K_1 } \right)$$ wobei [DMA] und [PrONO] totale Konzentrationen darstellen. Bei 298.2 K undI=0.25M gilt:k 2=(6.59±0.13)·10−2 M −1 s−1 undK 1=(1.16±0.07)· 10−11 M. Der beobachtete Einfluß der Ionenstärke, die kinetischen Resultate in Wasser/Tetrahydrofuran-Mischungen und in schwerem Wasser (k H/k D=2.09), und der Wert von ΔS #(−158 J K−1 mol−1) legen nahe, daß das nitrosierende AgensPrONO das freie Amin unter Ausbildung eines tetrazentrischen Übergangszustandes angreift, wobei dies der geschwindigkeitsbestimmende Schritt der Reaktion ist. Experimentelle Daten mit anderen Nitritestern zeigten eine gute Korrelation zurTaft-Gleichung. Mit einem Wert von ρ*=3.89 fürDMA erhält man eine Beziehung zwischen Struktur und Reaktivität, die es erlaubt, die Geschwindigkeitskonstante für Salpetrige Säure zu errechnen.
    Notes: Abstract A kinetic study of the mechanism of the nitrosation of dimethylamine (DMA) by propyl nitrite (PrONO) in basic media to yield N-nitrosodimethylamine (NDMA) has found the rate equation to be $$v = d[NDMA]/dt = k_2 [DMA][PrONO]/\left( {1 + \left[ {H^ + } \right]/K_1 } \right)$$ where [DMA] and [PrONO] are total concentrations. At 298.2 K andI=0.25M,k 2=(6.59±0.13)·10−2 M −1 s−1 andK 1=(1.16±0.07)·10−11 M. The observed influence of ionic strength, the kinetic results obtained in water/tetrahydrofuran mixtures and in heavy water (k H/k D=2.09), and the value of ΔS # (−158 JK−1 mol−1) suggest that the nitrosating agentPrONO attacks the free amine to create a tetracentric transition state and that this is the rate controlling step of the reaction. Experiments carried out with other nitrite esters have shown there to be a correlation satisfyingTaft's equation between their structure and their reactivity withDMA (ρ*=3.89), which allows the rate constant for nitrous acid to be calculated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00816527
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  • 7
    Electronic Resource
    Electronic Resource
    Estimation of the aggregation number and core radius of microemulsions (1992)
    Springer
    Monatshefte für Chemie 123 (1992), S. 383-389 
    Details
    ISSN: 1434-4475
    Keywords: Microemulsions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird eine einfache Methode zur Abschätzung von Aggregationszahl und Core-Radius von Mikroemulsionen aus Gewichtsmessungen von Natriumbis-2-ethylhexylsulphosuccinat (aerosol-OT oderAOT)/Decan/Wasser-Mikroemulsionen verschiedener Zusammensetzung vorgeschlagen. Unter den Annahmen, daß (i) die Dichte von Wasser innerhalb der Aggregationen die gleiche als bei freiem Wasser ist, (ii) das ganze Emulsionsmittel in der Grenzfläche vorliegt und (iii) das Eindringen der organischen Phase in die Grenzfläche vernachlässigbar ist, können Werte für Aggregationszahlen und Core-Radien erhalten werden, die durchaus mit entsprechenden Werten aus aufwendigeren Methoden vergleichbar sind. Das Leistungsverhältnis (Ergebnisse/geringer Aufwand) ist sehr vorteilhaft und macht die Methode für kinetische Arbeiten zur Bestimmung von Reaktionsmechanismen in Mikroemulsionen interessant.
    Notes: Summary A simple working method for the estimation of the aggregation numbers and core radii from weight measurements of sodium bis-2-ethylhexylsulphosuccinate (aerosol-OT orAOT)/decane/water microemulsions of several compositions is proposed. Starting out from the hypotheses that (i) the density of the water inside the droplets is the same as that of free water, (ii) all the surfactant is localized as interface, and (iii) the penetration of the organic phase into the interface is negligible, values for the aggregation number and core radii comparable to those determined using more sophisticated methods were obtained. The results/methodological simplicity ratio may be of great advantage in kinetic work on reaction mechanisms in microemulsions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00817593
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  • 8
    Electronic Resource
    Electronic Resource
    Kinetic studies on the formation of N-nitroso compounds IX. Nitrosyl acetate as a nitrosating agent (1984)
    Springer
    Monatshefte für Chemie 115 (1984), S. 669-682 
    Details
    ISSN: 1434-4475
    Keywords: Acetate buffer ; Kinetics of nitrosation ; Nitroso compounds ; Nitrosyl acetate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Untersuchung der Nitrosierung von N-Methylanilin und Piperazin mit Salpetriger Säure in Acetat-Puffer unterstützt einen für beide Fälle geltenden Mechanismus, dessen effektiver Ablauf von den Konzentrationsverhältnissen des Nitritions, des Acetations und der nitrosierbaren Substanz abhängt. Im Fall des N-Methylanilins ist das einzige Nitrosierungsagens Nitrosylacetat, während bei der Nitrosierung von Piperazin das Nitrit-Acidium-Ion und Distickstofftrioxid ebenfalls beteiligt sind. Die erhaltenen Resultate scheinen zu zeigen, daß die Nitrosierung durch Nitrosylacetat diffusionskontrolliert ist. Unter dieser Annahme kann die Gleichgewichtskonstante der ReaktionAcOH + HNO2 ⇆AcONO + H2O aus kinetischen Messungen zu etwa 1,4 · 10−8 M −1 abgeschätzt werden. Das bedeutet, daß die Konzentration von Nitrosylacetat im Medium extrem gering sein muß; das erklärt die praktische Undetektierbarkeit dieser Spezies in wäßriger Lösung, ausgenommen mit kinetischen Methoden.
    Notes: Abstract A study of the nitrosation of N-methylaniline and piperazine by nitrous acid in acetate buffer supports a mechanism covering both reactions, whose effective pathway depends on the relationship between the concentrations of nitrite ion, acetate ion, and nitrosatable substrate. In the case of N-methylaniline the only nitrosating agent is nitrosyl acetate, whereas in the nitrosation of piperazine the nitrous acidium ion and dinitrogen trioxide are also involved. The results obtained seem to show that nitrosation by nitrosyl acetate is diffusion controlled. On this assumption, the equilibrium constant of the reactionAcOH + HNO2 ⇆AcONO + H2O has been estimated from kinetic measurements as approximately 1.4 · 10−8 M −1. This means that the concentration of nitrosyl acetate in the medium must be extremely small, which explains the virtual impossibility of detecting it in aqueous solution except by kinetic methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01120962
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  • 9
    Electronic Resource
    Electronic Resource
    Kinetic studies on the formation of N-nitroso compounds (1984)
    Springer
    Monatshefte für Chemie 115 (1984), S. 155-163 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00798406
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  • 10
    Electronic Resource
    Electronic Resource
    Kinetic studies on the formation of N-nitroso compounds X. The nitrosation ofN-methylacetamide and its differences with respect to the nitrosation of amines (1984)
    Springer
    Monatshefte für Chemie 115 (1984), S. 1047-1057 
    Details
    ISSN: 1434-4475
    Keywords: Kinetics of nitrosation ; N-Nitrosation ofN-methylacetamide ; Proton transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Kinetik der Nitrosierung vonN-Methylacetamid wurde mittels Spektrophotometrie untersucht. Es wurden signifikante Unterschiede zum Mechanismus der Nitrosierung von Aminen beobachtet: die Abwesenheit einer Katalyse durch Halogenide, die Existenz einer generellen basischen Katalyse durch Acetat und dessen chlorierten Derivaten unter Übereinstimmung mit demBrønstedschen Gesetz (mit β=0,49) und einem beobachtbaren Isotopeneffekt (mit einem Verhältnis von 7,9 zwischen den Geschwindigkeitskonstanten in H2O und D2O). All das zeigt an, daß der geschwindigkeitsbestimmende Schritt im Mechanismus der Transfer eines Protons vom protonierten Nitrosamid zum Reaktionsmedium sein muß.
    Notes: Abstract The kinetics of the nitrosation ofN-methylacetamide have been studied using spectrophotometry. Significant differences with respect to the mechanism of nitrosation of amines were observed: the absence of catalysis by halides, the existence of general basic catalysis by acetate and its chlorated derivatives obeyingBrønsted's law (with β=0.49), and the primary isotopic effect (with a ratio of 7.9 between the rate constants for the elementary process in H2O and D2O). All this indicates that the slow step of the mechanism must be the transfer of a proton from the protonated nitrosamide to the reaction medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00798771
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