Steric Effects in Acid-Catalyzed Decomposition and Base-Catalyzed Cyclization of 1-(2-Alkoxycarbonylphenyl)-3-phenyltriazenes

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Title:Steric Effects in Acid-Catalyzed Decomposition and Base-Catalyzed Cyclization of 1-(2-Alkoxycarbonylphenyl)-3-phenyltriazenes
Creators:
Pytela, Oldřich
Halama, Aleš
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 61, 5, pp. 751-763
Uncontrolled Keywords:Inductive effect, Triazenes, acid-catalyzed decomposition of, Steric effects, Triazenes, base-catalyzed cyclization of

Abstract

Eight derivatives of 1-(2-alkoxycarbonylphenyl)-3-phenyltriazene (R = methyl, ethyl, propyl, isopropyl, butyl, isobutyl, hexyl, and allyl) have been synthesized and their UV-VIS, IR, <sup>1</sup>H and <sup>13</sup>C NMR spectra measured. The NMR spectra have been interpreted in detail. The kinetics of acid-catalyzed decomposition and base-catalyzed cyclization of the title compounds have been measured in 52.1% w/w methanol at 25.0 °C. The unit reaction order has been verified and the cyclization product has been identified. The pH-profiles obtained have been used to calculate the catalytic rate constants <i>k</i><sub>A </sub>(acid-catalyzed decomposition) and <i>k</i><sub>B </sub>(base-catalyzed cyclization) of all the derivatives; the constants have been interpreted with regard to inductive and steric effects. The catalytic rate constant <i>k</i><sub>A </sub>has been found to be independent of the substituents. The catalytic rate constant <i>k</i><sub>B </sub>depends statistically significantly upon both inductive and steric effects, the sensitivity to the former being more significant. The experimental results and their interpretation confirm the base-catalyzed cyclization mechanism with formation of tetrahedral intermediate as the rate-limiting step. <p>

Title:Steric Effects in Acid-Catalyzed Decomposition and Base-Catalyzed Cyclization of 1-(2-Alkoxycarbonylphenyl)-3-phenyltriazenes
Creators:
Pytela, Oldřich
Halama, Aleš
Uncontrolled Keywords:Inductive effect, Triazenes, acid-catalyzed decomposition of, Steric effects, Triazenes, base-catalyzed cyclization of
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:61
Number:5
Page Range:pp. 751-763
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19960751UNSPECIFIED
ID Code:975
Item Type:Article
Deposited On:06 Feb 2009 17:05
Last Modified:06 Feb 2009 16:05

Citation

Pytela, Oldřich; Halama, Aleš (1996) Steric Effects in Acid-Catalyzed Decomposition and Base-Catalyzed Cyclization of 1-(2-Alkoxycarbonylphenyl)-3-phenyltriazenes. Collection of Czechoslovak Chemical Communications, 61 (5). pp. 751-763. ISSN 0010-0765

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