Rate Coefficients for the OH Reaction with CF3SCF3: Atmospheric Lifetime and Global Warming Potential

Abstract

Bis(trifluoromethyl) sulfide (CF3SCF3) is a candidate insulating gas whose atmospheric persistence is poorly constrained: the structure–activity relationship cannot be reliably extrapolated to this perfluorinated species, and the only available theoretical estimate has not yet been tested against experiment. We measured the rate coefficient of its dominant atmospheric loss, reaction with OH, by pulsed laser photolysis–laser-induced fluorescence over 272–328 K at 50 Torr. The reaction is slow and nearly temperature independent, with k1(298 K) = (2.15 ± 0.34) × 10–15 cm3 molecule–1 s–1 and a slight positive trend (apparent Ea = (0.30 ± 0.14) kcal mol–1). No O2 dependence was detectable at 50 Torr. The measured k1 exceeds the theoretical value by approximately an order of magnitude, implying an OH-initiated lifetime of ∼14.7 years and a 100-year GWP of ∼2570, well below that of SF6 (24300), supporting further evaluation of CF3SCF3 as an alternative dielectric gas.