Assessing 2‑Fluorobutane (CH₃CHFCH₂CH₃) as a Climate-Friendly Alternative: Atmospheric Chemistry and Global Warming...

2-Fluorobutane (HFC-3-10-1se, CH₃CHFCH₂CH₃), a simple fluoroalkane, has received less attention than other widely used hydrofluorocarbons. Understanding its atmospheric chemistry is essential for evaluating its potential as a low- Global Warming Potential (GWP) alternative in industrial applications. Currently, only estimates of GWP relative to carbon dioxide (CO₂) at time horizons of 20 and 100 years (GWP₂₀ and GWP₁₀₀) have been reported to be 4 and 1, respectively, based on the calculated radiative efficiency (RE) and estimated rate coefficients (k _OH) for the gas-phase reaction of hydroxyl (OH) radicals. Here, we present the first experimental kinetic study of the gas-phase reaction of OH radicals with CH₃CHFCH₂CH₃ using a pulsed laser photolysis/laser-induced fluorescence technique (PLP-LIF) (T = 264.0-353.2 K; P = 60-230 Torr of helium). Contrary to previous estimates, no temperature dependence of the OH-rate coefficients, k _OH(T), was observed. A weighted average of k _OH(T)=(1.75 ± 0.56)×10^-12 cm³ molecule^-1 s^-1 corresponds to a global tropospheric lifetime, τ_OH, of 6.7 days. Additionally, the ultraviolet (UV, λ = 190-300 nm) and infrared (IR, 3500-500 cm^-1) absorption cross sections of CH₃CHFCH₂CH₃ were determined at 298 K by gas-phase UV and Fourier Transform infrared (FTIR) spectroscopies. No absorption above 219 nm was observed, therefore UV photolysis of 2-fluorobutane in the solar actinic region (λ > 290 nm) is not expected. From the IR absorption cross sections, the instantaneous radiative efficiency (RE_inst) was calculated to be 0.0562 W m^-2 ppbv^-1, while RE with atmospheric lifetime correction and adjustment for stratospheric temperature was 0.0037 W m^-2 ppbv^-1. Using lifetime corrected RE and τ_OH values, GWP₂₀ and GWP₁₀₀ were calculated to be 0.220 and 0.062. These findings suggest that its rapid atmospheric removal minimizes its contribution to climate change.