Atmospheric Chemistry of CFH ₂ CH ₂ CH ₂ CFH ₂ : Kinetics and Mechanism of Reactions With Cl Atoms and OH Radicals

ABSTRACT The atmospheric chemistry of 1,4‐difluorobutane (CFH 2 CH 2 CH 2 CFH 2 ) was investigated through a kinetic and mechanistic study of the reaction with chlorine (Cl) atoms and hydroxyl (OH) radicals. Using Fourier transform infrared (FTIR) spectroscopy and relative rate methods, the rate constants ( k ) for the reactions were determined at 298 ± 2 K as k (Cl + CFH 2 CH 2 CH 2 CFH 2 ) = (2.96 ± 0.31) × 10 −11 cm 3 molecule −1 s −1 and k (OH + CFH 2 CH 2 CH 2 CFH 2 ) = (8.23 ± 0.77) × 10 −13 cm 3 molecule −1 s −1 . The major product formed in both reactions was HC(O)F. Additional primary and secondary products were observed, and a proposed degradation mechanism is presented. The atmospheric lifetime of 1,4‐difluorobutane with respect to reaction with OH radicals was determined to be 29 days. The IR spectrum of 1,4‐difluorobutane was obtained using FTIR at Copenhagen Center for Atmospheric Research (CCAR) and at University of Castilla–La Mancha (UCLM). From these measurements, the radiative efficiency of CFH 2 CH 2 CH 2 CFH 2 was calculated resulting in a lifetime‐adjusted effective radiative efficiency of 0.015 W m −2 ppb −1 . The Global Warming Potential (GWP) values for CFH 2 CH 2 CH 2 CFH 2 were determined to 3.1, 0.9, and 0.3 for time horizons of 20, 100, and 500 years, respectively.