Effect of Medium on Acid-Catalyzed Decomposition of N-(Phenylazo)-Substituted Nitrogen Heterocycles

[img]PDF - Authorized users only
Language: English
128Kb
Title:Effect of Medium on Acid-Catalyzed Decomposition of N-(Phenylazo)-Substituted Nitrogen Heterocycles
Creators:
Ludwig, Miroslav
Bednářová, Iva
Pařík, Patrik
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 64, 10, pp. 1654-1672
Uncontrolled Keywords:Chemometrics, Solvent effects, Reaction kinetics, Mechanism, Triazenes

Abstract

Four <i>N</i>-(phenylazo)-substituted saturated nitrogen heterocyclics were synthesized and their structure was confirmed by <sup>1</sup>H and <sup>13</sup>C NMR spectroscopy. The kinetics of their acid-catalyzed decomposition were studied at various concentrations of the catalyst (pivalic acid) in 40, 30, and 20% (v/v) aqueous ethanol at 25 °C. The values obtained for the observed rate constants were processed by the non-linear regression method according to the suggested kinetic models and by the method of principal component analysis (PCA). The interpretation of the results has shown that the acid-catalyzed decomposition of the heterocyclics under the conditions used proceeds by the mechanism of general acid catalysis, the proton being the dominant catalyst particle of the rate-limiting step. The decrease in the observed rate constant at higher concentrations of the catalyst was explained by the formation of a non-reactive complex composed of the undissociated acid and the respective <i>N</i>-(phenylazo)heterocycle. The effect of medium and steric effect of the heterocyclic moiety on the values of catalytic rate constant are discussed. <p>

Title:Effect of Medium on Acid-Catalyzed Decomposition of N-(Phenylazo)-Substituted Nitrogen Heterocycles
Creators:
Ludwig, Miroslav
Bednářová, Iva
Pařík, Patrik
Uncontrolled Keywords:Chemometrics, Solvent effects, Reaction kinetics, Mechanism, Triazenes
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:64
Number:10
Page Range:pp. 1654-1672
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19991654UNSPECIFIED
ID Code:1587
Item Type:Article
Deposited On:06 Feb 2009 17:10
Last Modified:06 Feb 2009 16:10

Citation

Ludwig, Miroslav; Bednářová, Iva; Pařík, Patrik (1999) Effect of Medium on Acid-Catalyzed Decomposition of N-(Phenylazo)-Substituted Nitrogen Heterocycles. Collection of Czechoslovak Chemical Communications, 64 (10). pp. 1654-1672. ISSN 0010-0765

Repository Staff Only: item control page