Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Avda. Camilo José Cela, s/n. 13071 Ciudad Real, Spain.
J Phys Chem A. 2012 Jun 21;116(24):6041-50. doi: 10.1021/jp2111633. Epub 2012 Feb 10.
Fluorinated alcohols, such as 2,2,3,3-tetrafluoropropanol (TFPO, CHF(2)CF(2)CH(2)OH) and 2,2,3,3,3-pentafluoropropanol (PFPO, CF(3)CF(2)CH(2)OH), can be potential replacements of hydrofluorocarbons with large global warming potentials, GWPs. IR absorption cross sections for TFPO and PFPO were determined between 4000 and 500 cm(-1) at 298 K. Integrated absorption cross sections (S(int), base e) in the 4000-600 cm(-1) range are (1.92 ± 0.34) × 10(-16) cm(2) molecule(-1) cm(-1) and (2.05 ± 0.50) × 10(-16) cm(2) molecule(-1) cm(-1) for TFPO and PFPO, respectively. Uncertainties are at a 95% confidence level. Ultraviolet absorption spectra were also recorded between 195 and 360 nm at 298 K. In the actinic region (λ > 290 nm), an upper limit of 10(-23) cm(2) molecule(-1) for the absorption cross sections (σ(λ)) was reported. Photolysis in the troposphere is therefore expected to be a negligible loss for these fluoropropanols. In addition, absolute rate coefficients for the reaction of OH radicals with CHF(2)CF(2)CH(2)OH (k(1)) and CF(3)CF(2)CH(2)OH (k(2)) were determined as a function of temperature (T = 263-358 K) by the pulsed laser photolysis/laser induced fluorescence (PLP-LIF) technique. At room temperature, the average values obtained were k(1) = (1.85 ± 0.07) × 10(-13) cm(3) molecule(-1) s(-1) and k(2) = (1.19 ± 0.03) × 10(-13) cm(3) molecule(-1) s(-1). The observed temperature dependence of k(1)(T) and k(2)(T) is described by the following expressions: (1.35 ± 0.23) × 10(-12) exp{-(605 ± 54)/T} and (1.36 ± 0.19) × 10(-12) exp{-(730 ± 43)/T} cm(3) molecule(-1) s(-1), respectively. Since photolysis of TFPO and PFPO in the actinic region is negligible, the tropospheric lifetime (τ) of these species can be approximated by the lifetime due to the homogeneous reaction with OH radicals. Global values of τ(OH) were estimated to be of 3 and 4 months for TFPO and PFPO, respectively. GWPs relative to CO(2) at a time horizon of 500 years were calculated to be 8 and 12 for TFPO and PFPO, respectively. Despite the higher GWP relative to CO(2), these species are not expected to significantly contribute to the greenhouse effect in the next decades since they are short-lived species and will not accumulate in the troposphere even as their emissions grow up.
氟醇，如 2,2,3,3-四氟-1-丙醇（TFPO，CHF(2)CF(2)CH(2)OH）和 2,2,3,3,3-五氟-1-丙醇（PFPO，CF(3)CF(2)CH(2)OH），可以作为全球变暖潜能值（GWP）较大的氢氟碳化物的潜在替代品。在 298 K 下，测定了 TFPO 和 PFPO 在 4000 到 500 cm(-1) 之间的红外吸收截面。在 4000-600 cm(-1) 范围内的积分吸收截面（S(int)，base e）分别为（1.92 ± 0.34）×10(-16) cm(2) molecule(-1) cm(-1)和（2.05 ± 0.50）×10(-16) cm(2) molecule(-1) cm(-1)，用于 TFPO 和 PFPO。不确定性处于 95%置信水平。还在 298 K 下记录了紫外吸收光谱，在 195 到 360nm 之间。在光化区（λ > 290nm），报道了吸收截面（σ(λ)）的上限为 10(-23) cm(2) molecule(-1)。因此，预计这些氟丙醇在对流层中的光解不会导致明显的损失。此外，通过脉冲激光光解/激光诱导荧光（PLP-LIF）技术，确定了 OH 自由基与 CHF(2)CF(2)CH(2)OH（k(1)）和 CF(3)CF(2)CH(2)OH（k(2)）反应的绝对速率系数作为温度（T = 263-358 K）的函数。在室温下，获得的平均值为 k(1) = (1.85 ± 0.07) × 10(-13) cm(3) molecule(-1) s(-1)和 k(2) = (1.19 ± 0.03) × 10(-13) cm(3) molecule(-1) s(-1)。k(1)(T)和 k(2)(T)的观察到的温度依赖性由以下表达式描述：(1.35 ± 0.23) × 10(-12) exp{-(605 ± 54)/T}和 (1.36 ± 0.19) × 10(-12) exp{-(730 ± 43)/T} cm(3) molecule(-1) s(-1)，分别。由于 TFPO 和 PFPO 在光化区的光解可以忽略不计，因此这些物质的对流层寿命（τ）可以近似为与 OH 自由基的均相反应的寿命。TFPO 和 PFPO 的全球值分别估计为 3 和 4 个月。在 500 年的时间跨度内，相对于 CO(2)的全球变暖潜能值（GWP）分别计算为 8 和 12。尽管相对于 CO(2)的 GWP 较高，但由于这些物质是短寿命物质，即使它们的排放量增加，也不会在对流层中积累，因此它们在未来几十年内预计不会对温室效应产生重大影响。
