Kinetics of the gas-phase homogeneous unimolecular elimination of selected ethyl esters of 2-oxo-carboxylic acids

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. 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 kinetic and thermodynamic parameters of these reactions, together with those reported in the literature, lead to consider three different mechanistic pathways of elimination.