Kinetics of the reactions of hydroxyl radicals with some halocarbons: CHFCl2, CHF2Cl, CH3CCl3, C2HCl3, and C2Cl4

Abstract

Rate constants for the reactions of hydroxyl radicals with five halocarbons were measured in a discharge-flow apparatus using resonance fluorescence detection for OH in the 109 – 1011 cm−3 concentration range and with large excess of halocarbon. Over the approximate temperature range of 250 – 400°K the three saturated halocarbons CHFCl2, CHF2Cl, and CH3CCl3 had Arrhenius rate constant expressions of 1.16×10−12 exp(−1073/T), 1.20×10−12 exp(−1657/T), and 1.95×10−12 exp(−1331/T) cm3 sec−1, respectively. For the C2HCl3 and C2Cl4+OH reactions, Arrhenius expressions of 5.3×10−13 exp(445/T) and 9.4×10−12 exp(−1199/T) cm3 sec−1 are reported. These findings are compared with results by other investigators and their kinetic significance as well as their implications for stratospheric pollution problems are discussed.