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

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, τOH, 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 (REinst) 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 τOH 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.