Kinetic study of the reactions of CF3O2 radicals with Cl and NO

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 (DFMS). 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)×10-11 cm3 molecule-1 s-1 is in very good agreement with all previous values. For the reaction CF3O2+Cl, we obtain a rate constant at 298 K of (4.2±0.8)×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 abinitio theoretical study was performed to gain insights on the different postulated reaction pathways. There is a significant disagreement between experimental and abinitio 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.