Kinetic Study of the Reactions of CF3O2 Radicals with Cl and NO

Published

October 1, 1999

Author(s)

F Louis, Donald R. Burgess Jr., M Rayez, J P. Sawerysyn

Abstract

Kinetic studies of the reactions CF₃O₂ + Cl and CF₃O₂ + NO were performed at room temperature in the gas phase using the discharge flow/mass spectrometric technique (DF/MS). The reactions were investigated under pseudo-first-order conditions with Cl or NO in large excess with respect to the CF₃O₂ radicals. The rate constant for the reaction CF₃O₂ +NO was measured at 298 K and the value of (1.6 0.3} x 10^-11 cm ³ molecule^-1 s^-1 is in very good agreement with all previous values. For the reaction CF₃O₂ + Cl, we obtain a rate constant 298 K of (4.2 0.8) x 10^-11 cm³ .molecule^-1 s^-1 in excellent agreement with the only published value. Product analysis shows that this reaction occurs via the major reaction pathway CF₃O₂ + Cl -> CF₃O + ClO at room temperature. In addition, an ab initio theoretical study was performed to gain insights on the different postulated reaction pathways. There is a significant disagreement between experimental and ab initio values recommended for the formation enthalpies of CF₂O, CF₃O and related molecules produced in this system. Consequently, we provide self-consistent values of enthalpies based on isodesmic reactions for the CF₃O₂ + Cl reaction system using the G2, G2(MP2) and CBS-Q methods. These values are also compared with BAC-MP4 heats of formation calculated in this work.

Citation

Physical Chemistry Chemical Physics

Volume

1

Pub Type

Journals

Keywords

ab initio, chemical kinetic, environment, HFC's, rate measurement, stratospheric ozone

Citation

Louis, F. , Burgess Jr., D. , Rayez, M. and Sawerysyn, J. (1999), Kinetic Study of the Reactions of CF₃O₂ Radicals with Cl and NO, Physical Chemistry Chemical Physics (Accessed July 18, 2024)