Kinetics of the gas‐phase homogeneous unimolecular elimination of selected ethyl esters of 2‐oxo‐carboxylic acids |
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Authors: | Andreina Reyes Rosa M Domínguez Maria Tosta Armando Herize Gabriel Chuchani |
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Institution: | Centro de Química, Instituto Venezolano de Investigaciones Científicas (IVIC), Apartado, Caracas, Venezuela |
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Abstract: | The gas‐phase elimination kinetics of selected ethyl esters of 2‐oxo‐carboxylic acid have been studied over the temperature range of 270–415 °C and pressures of 37–114 Torr. The reactions are homogeneous, unimolecular, and follow a first‐order rate law in a seasoned static reaction vessel, with an added free radical suppressor toluene. The observed overall and partial rate coefficients are expressed by the following Arrhenius equations: - Ethyl oxalyl chloride
- log koverall (s?1) = (13.22 ± 0.45) ? (179.4 ± 4.9) kJ mol?1 (2.303 RT)?1
- Ethyl piperidineglyoxylate
- log k(CO2) (s?1) = (12.00 ± 0.30) ? (191.2 ± 3.9) kJ mol?1 (2.303 RT)?1
- log k(CO) (s?1) = (12.60 ± 0.09) ? (210.7 ± 1.2) kJ mol?1 (2.303 RT)?1
- log kt(overall) (s?1) = (12.22 ± 0.26) ? (193.4 ± 3.4) kJ mol?1 (2.303 RT)?1
- Ethyl benzoyl formate
- log k(CO2) (s?1) = (12.89 ± 0.72) ? (203.8 ± 9.0) kJ mol?1 (2.303 RT)?1
- log k(CO) (s?1) = (13.39 ± 0.31) ? (213.3 ± 3.9) kJ mol?1 (2.303 RT)?1
- log kt(overall) (s?1) = (13.24 ± 0.60) ? (205.8 ± 7.6) kJ mol?1 (2.303 RT)?1
The kinetic and thermodynamic parameters of these reactions, together with those reported in the literature, lead to consider three different mechanistic pathways of elimination. Copyright © 2010 John Wiley & Sons, Ltd. |
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Keywords: | ethyl benzoyl formate ethyl oxalyl chloride ethyl piperidineglyoxylate gas‐phase elimination kinetics mechanism |
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