Atmospheric Degradation of Perfluoro-2-methyl-3-pentanone: Photolysis, Hydrolysis and Hydration

Abstract

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.

Photolysis study of fluorinated ketones under natural sunlight conditions

“…The maximum absorbance was found at 306 nm with s max = (6.38 AE 0.32) Â 10 À20 cm 2 molecule À1 , in good agreement with those reported in previous studies. 4,5 In Fig. 4,5 In Fig.…”

“…5 Previous studies have shown that PFMP reactions with OH and Cl atoms are very slow. Furthermore, this procedure may be extended to other terrestrial locations through calculation of the average actinic radiation at the corresponding latitudes, as described for PFMP.…”

The Effect of Epoxy Resin on the Properties of Encapsulated Fire Extinguishing Agent

“…The effect of UV radiation on the properties of EFA and EP composite material containing EFA are analyzed. It is known (13) that NovecTM1230 decomposes under the influence of UV. Samples of pure EFA and EP composite containing EFA were kept at the average UV radiation value (5000 MJ/m 2 ) from 1 to 50 hours at 25 ℃.…”

“…Perfluoro (2-methyl-3-pentanone) (FK-5-1-12, 3M TM Novec TM 1230) is one of the most promising agents (11) . It is aligned with the Montreal Protocol and is a liquid under normal conditions (12,13) .…”

Environmental and safety aspects of AirPlus insulated GIS

“…As with other compounds that contain no halogen other than fluorine, the ozone depletion potential (ODP) is zero. In addition, we determined that the atmospheric degradation of fluoroketones do not lead to the generation of long chain acids that are of environmental concern [6]. For liquid fluoroketone, care must be taken to prevent its discharge into water.…”