Kinetics of OH radical reaction with CF3CHFCH2F (HFC-245eb) between 200 and 400K: G3MP2, G3B3 and transition state theory calculations

Abstract

The rate coefficients of hydroxyl radical (OH) reaction with CF 3 CHFCH 2 F (HFC-245eb) were computed using G3MP2 and G3B3 theories between 200 and 400 K. Nine different transition states were identified for the title reaction and confirmed by intrinsic reaction coordinate (IRC) calculations. The contributions of all the individual hydrogen atoms in different rotamers for the title reaction were computed and compared with the results obtained by experimental methods and structure activity relationships (SAR). The rate coefficients for the title reaction were computed to be k = (1.57 ± 0.14) × 10 −13 exp[−(690 ± 26)/ T ] cm 3 molecule −1 s −1 at G3MP2, and k = (0.97 ± 0.13) × 10 −13 exp[−(513 ± 39)/ T ] cm 3 molecule −1 s −1 at G3B3 theories. Theoretically calculated rate coefficients are found to be in good agreement with the experimental results. The tropospheric lifetime of CF 3 CHFCH 2 F because of its reaction with OH radicals are computed to be 2.52 and 2.14 years at G3MP2 and G3B3 level of theories, respectively.