Kinetics of the OH + CH3CF2Cl Reaction over an Extended Temperature Range

Rate coefficients of the reaction of hydroxyl (OH) radicals with CH 3 CF 2 Cl over an extended temperature range are reported. Measurements were performed using a laser photolysis/laser-induced fluorescence technique under slow flow conditions at a total pressure of 740 ± 10 Torr. Arrhenius plots of the data exhibited significant curvature and were fitted to the form of k ( T ) = AT B exp(− C / T ). A semiempirical fitting approach was used in which A and B were obtained from transition state theory (TST) and C was determined from a nonlinear least-squares fit to the experimental data. Ab initio calculations were used to reveal the thermochemical properties of the activated complex. The resulting modified Arrhenius expression was k (295−808 K) = (1.20 ± 0.32) × 10 -17 T 1.89±0.05 exp[(−1541 ± 128)/ T ] cm 3 molecule -1 s -1 . This semiempirical fit is shown to be superior to a purely empirical fit to the data. The expression was in good agreement with experimental results and previous experimental studies between temperatures of 240 and 480 K. The TST-based modified Arrhenius expression is compared to previous TST and structure−activity relationship predictions.