Rate coefficients over the temperature range 206–380 K are reported for the gas-phase reaction of OH radicals with 2,3,3,3-tetrafluoropropene (CF₃CFCH₂), k₁(T), and 1,2,3,3,3-pentafluoropropene ((Z)-CF₃CFCHF), k₂(T), which are major components in proposed substitutes for HFC-134a (CF₃CFH₂) in mobile air-conditioning units. Rate coefficients were measured under pseudo-first-order conditions in OH using pulsed-laser photolysis to produce OH and laser-induced fluorescence to detect it. Rate coefficients were found to be independent of pressure between 25 and 600 Torr (He, N₂). For CF₃CFCH₂, the rate coefficients, within the measurement uncertainty, are given by the Arrhenius expression k₁(T) = (1.26 ± 0.11) × 10⁻¹² exp[(−35 ± 10)/T] cm³ molecule⁻¹ s⁻¹ where k₁(296 K) = (1.12 ± 0.09) × 10⁻¹² cm³ molecule⁻¹ s⁻¹. For (Z)-CF₃CFCHF, the rate coefficients are given by the non-Arrhenius expression k₂(T) = (1.6 ± 0.2) × 10⁻¹⁸T² exp[(655 ± 50)/T] cm³ molecule⁻¹ s⁻¹ where k₂(296 K) = (1.29 ± 0.06) × 10⁻¹² cm³ molecule⁻¹ s⁻¹. Over the temperature range most relevant to the atmosphere, 200–300 K, the Arrhenius expression k₂(T) = (7.30 ± 0.7) × 10⁻¹³ exp[(165 ± 20)/T] cm³ molecule⁻¹ s⁻¹ reproduces the measured rate coefficients very well and can be used in atmospheric model calculations. The quoted uncertainties in the rate coefficients are 2σ (95% confidence interval) and include estimated systematic errors. The global warming potentials for CF₃CFCH₂ and (Z)-CF₃CFCHF were calculated to be <4.4 and <3.6, respectively, for the 100 year time horizon using infrared absorption cross sections measured in this work, and atmospheric lifetimes of 12 and 10 days that are based solely on OH reactive loss.

Hydrochlorofluorocarbons (HCFCs) are ozone depleting substances and potent greenhouse gases that are controlled under the Montreal Protocol. However, the majority of the 274 HCFCs included in Annex C of the protocol do not have reported global warming potentials (GWPs) which are used to guide the phaseout of HCFCs and the future phase down of hydrofluorocarbons (HFCs). In this study, GWPs for all C₁–C₃ HCFCs included in Annex C are reported based on estimated atmospheric lifetimes and theoretical methods used to calculate infrared absorption spectra. Atmospheric lifetimes were estimated from a structure activity relationship (SAR) for OH radical reactivity and estimated O(¹D) reactivity and UV photolysis loss processes. The C₁–C₃ HCFCs display a wide range of lifetimes (0.3 to 62 years) and GWPs (5 to 5330, 100-year time horizon) dependent on their molecular structure and the H-atom content of the individual HCFC. The results from this study provide estimated policy-relevant GWP metrics for the HCFCs included in the Montreal Protocol in the absence of experimentally derived metrics.