Kinetics and mechanism of gas-phase pyrolysis of N-aryl-3-oxobutanamide ketoanilides, their 2-arylhydrazono derivatives, and related compounds
✍ Scribed by Rana N. Malhas; Nouria A. Al-Awadi; Osman M. E. El-Dusouqui
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 295 KB
- Volume
- 39
- Category
- Article
- ISSN
- 0538-8066
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Rates and products of reaction and Arrhenius activation parameters were determined for the gas‐phase thermolysis of 14 substrates of the title compounds using sealed pyrex reactor tubes and HPLC/UV‐VIS to monitor substrate pyrolysis. The 14 compounds under study are N‐phenyl‐3‐oxo‐ (1), N‐(p‐chlorophenyl)‐3‐oxo‐ (2), N‐(p‐methylphenyl)‐3‐oxo‐ (3), and N‐(p‐methoxyphenyl)‐3‐oxobutanamide (4), in addition to (i) four substrates (5–8) obtained by the replacement of the pairs of methylene hydrogens at the 2‐position of compounds (1–4), each pair by a phenylhydrazono group; (ii) three arylhydrazono derivatives (9–11) in which Cl, CH~3~, or OCH~3~ groups are substituted at the para position of the phenylhydrazono moiety of compound 5; (iii) 3‐oxobutanamide (acetoacetamide, 12), N‐phenyl‐3‐oxo‐3‐phenylpropanamide (13), and N,N′‐diphenylpropanediamide (14). The reactions were conducted over 374–546 K temperature range, and the values of the Arrhenius log A(s^−1^) and E~a~(kJ mol^−1^) of these reactions were, respectively, 12.0 ± 2.0 and 119.2 ± 17.0 for the ketoanilides (1–4, 12–14), and 13.0 ± 0.7 and 157.5 ± 8.6 for the arylhyrazono compounds (5–11). Kinetically, the arylhydrazono derivatives were found to be ca. 1.4 × 10^3^ to 5.7 × 10^3^ times less reactive than the parent ketoanilides. A mechanism is proposed to account for reaction products and to rationalize molecular reactivities. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 39: 82–91, 2007