An experimental and theoretical study on the reaction of Cl with CF3CF2CH2OH

Abstract

An absolute kinetic study of the reaction of Cl atoms with CF3CF2CH2OH is reported as a function of temperature (T = 268–377 K) and at a total pressure of 100 Torr by the Pulsed Laser Photolysis - Resonance Fluorescence (PLP-RF) technique. No pressure dependence of the rate coefficient for the title reaction, k, was observed between 50 and 200 Torr of He at 298 K. The derived Arrhenius expression in that T-range was k(T) = (2.18 ± 0.24) × 10−12 exp(–(333 ± 34)/T) cm3 molecule−1 s−1, where the uncertainties are ±2σ. From these results, the average tropospheric lifetime of CF3CF2CH2OH due to the reaction with Cl was estimated to be 50 years, considering a global Cl concentration of 103 atom cm−3 and an average temperature of 272 K. Additionally, a theoretical study of the Cl + CF3CF2CH2OH reaction has been carried out by ab initio Möller–Plesset second-order perturbation treatment with 6-311G** basis set to investigate the reaction mechanism. Molecular energies of the different critical points of the potential energy surface have been calculated at QCISD(T) level. The theoretical study shows that the H-atom abstraction from the –CH2– group is the most favourable reaction pathway.