Perfluorinated carboxylic acids are widely distributed in the environment, including remote regions, but their sources are not well understood. Perfluoropropionic acid (PFPrA, CF(3)CF(2)C(O)OH) has been observed in rainwater but the observed amounts can not be explained by currently known degradation pathways. Smog chamber studies were performed to assess the potential of photolysis of perfluoro-2-methyl-3-pentanone (PFMP, CF(3)CF(2)C(O)CF(CF(3))(2)), a commonly used fire-fighting fluid, to contribute to the observed PFPrA loadings. The photolysis of PFMP gives CF(3)CF(2)C.(O) and .CF(CF(3))(2) radicals. A small (0.6%) but discernible yield of PFPrA was observed in smog chamber experiments by liquid chromatography-mass spectrometry offline chamber samples. The Tropospheric Ultraviolet-Visible (TUV) model was used to estimate an atmospheric lifetime of PFMP with respect to photolysis of 4-14 days depending on latitude and time of year. PFMP can undergo hydrolysis to produce PFPrA and CF(3)CFHCF(3) (HFC-227ea) in a manner analogous to the Haloform reaction. The rate of hydrolysis was measured using (19)F NMR at two different pHs and was too slow to be of importance in the atmosphere. Hydration of PFMP to give a geminal diol was investigated computationally using density functional theory. It was determined that hydration is not an important environmental fate of PFMP. The atmospheric fate of PFMP seems to be direct photolysis which, under low NO(x) conditions, gives PFPrA in a small yield. PFMP degradation contributes to, but does not appear to be the major source of, PFPrA observed in rainwater.

中文翻译：

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全氟-2-甲基-3-戊酮在大气中的降解：光解，水解和水合作用。

全氟羧酸广泛分布在环境中，包括偏远地区，但其来源尚不清楚。在雨水中已观察到全氟丙酸（PFPrA，CF（3）CF（2）C（O）OH），但目前已知的降解途径无法解释观察到的量。进行烟雾试验室研究以评估全氟-2-甲基-3-戊酮（PFMP，CF（3）CF（2）C（O）CF（CF（3））（2））的光解潜力使用的灭火液有助于观察到的PFPrA负荷。PFMP的光解产生CF（3）CF（2）C.（O）和.CF（CF（3））（2）自由基。在烟雾室实验中，通过液相色谱-质谱联用离线室样品观察到PFPrA的产量小（0.6％），但可辨别。对流层紫外线可见（TUV）模型用于估计PFMP在4-14天的光解过程中的大气寿命，具体取决于一年中的纬度和时间。PFMP可以水解，以类似于Haloform反应的方式产生PFPrA和CF（3）CFHCF（3）（HFC-227ea）。使用（19）F NMR在两个不同的pH值下测量水解速率，该水解速率太慢，无法在大气中发挥重要作用。使用密度泛函理论计算研究了PFMP的水合反应，生成了一种双晶二醇。确定水合不是PFMP的重要环境命运。PFMP在大气中的命运似乎是直接光解，在低NO（x）条件下，PFPrA的收率很小。PFMP降解是雨水中观察到的PFPrA的促成因素，但似乎不是其主要来源。