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

The rate coefficients of hydroxyl radical (OH) reaction with CF₃CHFCH₂F (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] cm³ molecule^-1 s^-1at G3MP2, and k = (0.97 ± 0.13) × 10^-13 exp[-(513 ± 39)/T] cm³ 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 CF₃CHFCH₂F 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.