Perfluorocarboxylates

CF COONa and higher perfluorocarboxylated salts (116,117), CF2S02Na (118), and esters such as CF2CICOOCH2 (119) or FSO2CF2COOCH2 (120), represents a novel trifluoromethylation concept. 

Membrane cells are the state of the art chlor-alkah technology as of this writing. There are about 14 different membrane cell designs in use worldwide (34). The operating characteristics of some membrane cells are given in Table 3. The membranes are perfluorosulfonate polymers, perfluorocarboxylate polymers, and combinations of these polymers. Membranes are usually reinforced with a Teflon fabric. Many improvements have been made in membrane cell designs to accommodate membranes in recent years (35,36). 

Direct perfluoroalkylatwn of electron poor aromatic and heterocyclic systems with perfluorocarboxylic acids is mediated by xenon difluonde [165] (equation 142)... 

Hori H, A Yamamoto, E Hayakawa, S Taniyasu, S Kutsuna, H Kiatagawa, R Arakawa (2005a) Efficient decomposition of environmentally persistent perfluorocarboxylic acids by use of persulfate as a photochemical oxidant. Environ Sci Technol 39 2383-2388. 

Hori H, A Yamamoto, S Kutsuna (2005b) Efficient photochemical decomposition of long-chain perfluorocarboxylic acids by means of an aqueous/liquid COj biphasic system. Environ Sci Technol 39 7692-7697. 

Wallington TJ, Hurley MD, Xia J, Wuebbles DJ, Sillman S, Ito A, Penner JE, Ellis DA, Martin J, Mabury SA, Nielsen OJ, Andersen MPS (2006) Formation of C7F15COOH (PFOA) and other perfluorocarboxylic acids during the atmospheric oxidation of 8 2 Fluorotelomer Alcohol. Environ Sci Technol 40 924-930... 

The 3M company uses electrochemical fluorination (ECF) technology for the production of over lOOt/year perfluorocarboxylic acid, sulphonic acids, alkanes, trialkylamines, alkyl ethers [48]. 

Perfluoroalkylsulfonyl fluorides, 11 865 Perfluorocarbons, 15 716-717 as blood substitutes, 4 112-113 Perfluorocarboxylate ionomers, 14 475 Perfluoroethers, thermal stabilities of, 11 879... 

Two independent analytical methods—LC-MS-MS and 19F-NMR— for the determination of perfluorinated anionic surfactants in environmental water samples were presented. Perfluorinated alkanesulfonates and perfluorocarboxylates were determined qualitatively and quantitatively because of an accidental release of perfluorosurfactant contaminated fire-fighting foam [55]. Ci8-SPE was applied for concentration of the compounds from water samples. Methanol was used for elution prior to ESI-LC-MS(—) analysis. The negatively recorded LC-MS-MS TIC for the determination of PFOS, PFHxS, PFOA, perfluor-oheptanoic acid (PFHpA), perfluorododecanoic acid (PFDoA internal standard) in water samples was presented [55]. 

Aromatic and a-substituted aliphatic aldehydes react with oxiranes under neutral conditions to yield 1,3-dioxoIanes [35] whereas a-unsubstituted aldehydes undergo a simple aldol condensation under such conditions. In a somewhat similar manner, perfluorocarboxylic esters react with oxiranes to produce cyclic orthoesters (-50%) [36]. The corresponding reaction with non-fluorinated esters fails. 

The oxirane (3 mmol), perfluorocarboxylic ester (3 mmol) and TBA-Br (48 mg, 0.15 mmol) are stirred at 90 °C for 24-72 h. The mixture is extracted with CH2C12 (3x15 ml) and the combined extracts are washed well with H20, dried (MgS04), and fractionally distilled to yield the orthoester. 

Selected examples of the ring-opening of oxiranes with perfluorocarboxylic esters... 

Under the agreement, companies will reduce emissions of these compounds from their facilities and consumer products by 95 per cent by 2010, and work towards eliminating the sources of PFOA by no later than 2015. Furthermore, PFOS and PFOA as well as other perfluorocarboxylic acids (PFCAs) are stable degradation products and/or metabolites of neutral PFCs such as fluorotelomer alcohols (PFTOHs), perfluorinated sulphonamides (PFASAs) and perfluorinated sulphonamide ethanols (PFASEs) [22]. Therefore, the largest global manufacturer and supplier of fluorotelomers such as Capstone, DuPont have adapted its entire product line to utilise short-chain chemistry because short-chain molecules cannot break down to PFOA in the environment. 

SPE strategies have been carried out using a variety of media according to the different polarities exhibited by PFCs. Ionic perfluorocarboxylates (PFCAs) and perfluorosulphonates (PFSAs) require moderately polar media (Oasis WAX-SPE or methanol and acetonitrile) for efficiently trapping of water-soluble short-chain... 

The applications of commercially available perfluorinated compounds have been reported in a number of recent pub-Kcations [395-397]. In the presence of perfluorocarboxylic acids, the current efficiency increased, and surface morphology... 

Employment of Zn—Cu couple is representative of another approach. For example, reaction of perfluoroalkyl iodides with carbonates gives fluorocarboxylic esters (equation 107)132. Similarly, reaction of perfluoroalkyl iodides with Zn—Cu couple and C02 or S02 in DMSO affords the perfluorocarboxylic acids and sulfonyl chlorides, respectively133. A double methylene inserted product is formed when dibromomethane is used as a substrate (equation 108)134. 

The preparation of many long-chain perfluorocarboxylic acids and diacids is now carried out on the industrial scale using direct fluorination techniques (Fig. 36) [15,16,100]. 

More recently, Rozen found that treating suspensions of sodium or potassium perfluorocarboxylates with fluorine in an inert solvent, such as trichlorofluoro-methane, afforded oxidising solutions which proved to be mixtures of hypofluorites (Fig.82) [190-192]. 

Armitage, J.M., MacLeod, M. and Cousins, I.T. (2009) Comparative assessment of the global fate and transport pathways of long-chain perfluorocarboxylic acids (PFCAS) and perfluorocarboxylates (PFCS) emitted from direct sourcess. Environ Sci Technol, 43, 5830-5836. 

---