Kinetics and Mechanism of the Formation and Decomposition of Imidazolin-4-ones from 2-(N-Benzoylamino)alkanamides in Aqueous Medium

[img]PDF - Authorized users only
Language: English
148Kb
Title:Kinetics and Mechanism of the Formation and Decomposition of Imidazolin-4-ones from 2-(N-Benzoylamino)alkanamides in Aqueous Medium
Creators:
Sedlák, Miloš
Hanusek, Jiří
Bína, Radim
Kaválek, Jaromír
Macháček, Vladimír
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 64, 10, pp. 1629-1640
Uncontrolled Keywords:Solvent isotope effect, Imidazolinones, Reaction kinetics, 2-Phenyl-5-imidazolinones, Mechanism of cyclization, 2-Benzoylaminoalkanamides

Abstract

The cyclization reactions of substituted 2-(<i>N</i>-benzoyl-<i>N</i>-methyl)aminoalkanamides <strong>1a</strong>-<strong>1g</strong> have been studied in aqueous medium. The Hammett reaction constant is ρ = 1.4 for the cyclization reactions of compounds <strong>1a</strong>-<strong>1e</strong> in sodium hydroxide solutions. 2-[<i>N</i>-Methyl- <i>N</i>-(4-nitrobenzoyl)amino]-2-(4-nitrophenyl)propanamide (<strong>1g</strong>) is cyclized to imidazolinone <strong>2g</strong> in aqueous amine buffers of pH 9-11.5; the reaction is subject to specific base catalysis in these media, and the rate-limiting step is the formation of a tetrahedral intermediate. In sodium hydroxide solution, the primary cyclization product is hydrolyzed to give an intermediate <strong>M</strong> which is subsequently decomposed to sodium 4-nitrobenzoate and 2-methylamino- 2-(4-nitrophenyl)propanamide. At low sodium hydroxide concentration, the rate-limiting step of the opening of imidazoline ring of compound <strong>2g</strong> is non-catalyzed decomposition of the intermediate. At higher sodium hydroxide concentrations, the other reaction path begins to make itself felt: hydroxide-ion-catalyzed decomposition of the intermediate. The dependence of observed rate constant of cyclization of compound <strong>1f</strong> on sodium hydroxide concentration was used to determine kinetically the value of p<i>K</i><sub>a</sub> = 13.5 ± 0.1. The kinetic deuterium isotope effect of cyclization of compounds <strong>1f</strong> giving <strong>2f</strong> (<i>k</i><sub>C</sub><sup>H</sup>/<i>k</i><sub>C</sub><sup>D</sup> = 1.7) was determined in solutions of NaOD in D<sub>2</sub>O. <p>

Title:Kinetics and Mechanism of the Formation and Decomposition of Imidazolin-4-ones from 2-(N-Benzoylamino)alkanamides in Aqueous Medium
Creators:
Sedlák, Miloš
Hanusek, Jiří
Bína, Radim
Kaválek, Jaromír
Macháček, Vladimír
Uncontrolled Keywords:Solvent isotope effect, Imidazolinones, Reaction kinetics, 2-Phenyl-5-imidazolinones, Mechanism of cyclization, 2-Benzoylaminoalkanamides
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. 1629-1640
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19991629UNSPECIFIED
ID Code:1585
Item Type:Article
Deposited On:06 Feb 2009 17:10
Last Modified:06 Feb 2009 16:10

Citation

Sedlák, Miloš; Hanusek, Jiří; Bína, Radim; Kaválek, Jaromír; Macháček, Vladimír (1999) Kinetics and Mechanism of the Formation and Decomposition of Imidazolin-4-ones from 2-(N-Benzoylamino)alkanamides in Aqueous Medium. Collection of Czechoslovak Chemical Communications, 64 (10). pp. 1629-1640. ISSN 0010-0765

Repository Staff Only: item control page