Perfluorinated acid

Pubhcations have described the use of HFPO to prepare acyl fluorides (53), fluoroketones (54), fluorinated heterocycles (55), as well as serving as a source of difluorocarbene for the synthesis of numerous cycHc and acycHc compounds (56). The isomerization of HFPO to hexafluoroacetone by hydrogen fluoride has been used as part of a one-pot synthesis of bisphenol AF (57). HFPO has been used as the starting material for the preparation of optically active perfluorinated acids (58). The nmr spectmm of HFPO is given in Reference 59. The molecular stmcture of HFPO has been deterrnined by gas-phase electron diffraction (13). 

Perfluorinated acid fluorides containing heteratoms are also accessible by ECF. Long-chain perfluorinated acid fluorides produced by ECF containing nitrogen (10—12), oxygen (13), and sulfur (14,15) have been reported. The fluorinated mixed sulfonic acid—carboxyflc acid precursors are also known. ECF of hydrocarbon sultones has led to formation of FS02(CF2) C0F, where n = 2,3 (16). 

During electrochemical fluorination retention of important functional groups or atoms in molecules is essential. Acyl fluorides and chlorides, but not carboxylic acids and anhydrides (which decarboxylate), survive perfluorination to the perfluorinated acid fluorides, albeit with some cyclization in longer chain (>C4) species [73]. Electrochemical fluorination of acetyl fluoride produces perfluoro-acetyl fluoride in 36-45% yields [85]. Electrochemical fluorination of octanoyl chloride results in perfluorinated cyclic ethers as well as perfluorinated octanoyl fluonde. Cyclization decreases as initial substrate concentration increases and has been linked to hydrogen-bonded onium polycations [73]. Cyclization is a common phenomenon involving longer (>C4) and branched chains. a-Alkyl-substituted carboxylic acid chlorides, fluorides, and methyl esters produce both the perfluorinated cyclic five- and six-membered ring ethers as well as the perfluorinated acid... 

Molecular ions are usually not observed with perfluorinated acids, but may be deduced by adding 17(OH) or 45 (C02H) Daltons to... 

Carboxylic acids with a halide, hydroxy or amino group in the a-position form no dimers (Table 2, No. 11), except when two or three fluorine atoms are pr ent there (Table 2, No. 12). A large amount of work has been devoted to the coupling of fluoro-carboxylic acids (Table 2, Nos. 13-16) due to interesting properties of the produced fluorohydrocarbons. By statistical analysis optimal conditions for Kolbe ela trolysis of perfluorinated acids have been calculated [135]. 

Dinglasan MJA, Y Ye, EA Edwards, SA Mabury (2004) Eluorotelomer alcohol biodegradation yields poly-and perfluorinated acids. Environ Sci Technol 38 2857-2864. 

By treating Nafion (NR-50), a perfluorinated acidic ion exchanger based on sulfonic acid groups, with scandium(III) chloride hexahydrate Kobayashi et al. generated a solid scandium-derived catalyst (29) (Nafion-Sc) that proved to be effective in al-lylation reactions of carbonyl compounds with tetraallyltin (Scheme 4.15). Since the catalyst is stable in both organic solvents and water, even unprotected carbohydrates could be transformed directly in aqueous solvents. The resulting homo-allylic alcohols were separated by simple filtration [97]. 

Yamashita, N. Kannan, K. Taniyasu, S. Horii, Y Okazawa, T. Petrick, G. Gamo, T. Analysis of Perfluorinated Acids at Parts-per-Quadrillion Levels in Seawater using Liquid Chromatography-Tandem Mass Spectrometry. Environ. Sci. Technol. 2004, 38, 5522-5528. 

Phillips, M.M., Dinglasan-Panlilio, M.J.A., Mabury, S.A., Solomon, K.R. and Sibley, P.K. (2007) Fluorotelomer acids are more toxic than perfluorinated acids. Environ Sci Technol, 41, 7159-7163. 

Keywords Perfluorinated acid Precursors Perfluorooctane sulfonamides ... 

DesMarteau et al. synthesised new perfluoroalkyl hypofluorites [44] and hypobromites [52]. The first ones were produced from perfluorinated acid fluorides or halogenated ketones as depicted in the following schemes [44] ... 

Finally perfluorinated alkenes, prepared according to various routes (decarboxylation of perfluorinated acids or anhydrides, action of organolithium, magnesium reagents or metallic zinc-copper couple to perfluoroalkyl iodides, oligomerisation of TFE and of HFP, addition of perfluoroalkyl iodides to per-fluoroallyl chloride [304], addition of KF to perhalogenated esters or alkanes... 

Kannan, K., Choi, J.W., Iseki, N., Senthilkumar, K., Kim, D.H., Masunaga, S., Giesy, J.P., 2002. Concentrations of perfluorinated acids in livers of birds from Japan and Korea. 

The usually accepted reaction mechanism [22-23] involves an a-diketonated intermediate which, in an alkali medium, leads to the salts of both corresponding perfluorinated acids as shown in the following scheme ... 

Moreover, the fluorinated gem-diols can be prepared by reduction of the corresponding perfluorinated acids in spite of the formation of the monoalcohol. This was illustrated by Sokoya s investigations [201] ... 

Martin, J. W., Mabury, S. A., Solomon, K. R. and Muir, D. C. G. (2003) Bioconcentration and tissue distribution of perfluorinated acids in rainbow trout (Oncorphynchus Mykiss). Environ. Toxicol. Chem., 22, 196. 

However, it is known that carboxylic perfluorinated acids, in particular perfluorooctanoic acid, accumulate in the living organisms and are environmentally persistent [68],... 

The acid-anhydrofluoride behavior of perfluorinated acids, not dissociating in H20... 

Substrates may be dip-coated in solutions or melts of the solid of interest. The technique has been applied, for example, to perfluorinated acids on platinum foil [175], to fluorosurfactants on glass, mica, or silicon wafer [69-72.166.172], and to the production of elastomeric films of butyl rubber [176], The properties of the resulting film are dependent on the concentration of the solution, which is usually low, and on the speed at which the substrate is withdrawn from the liquid. The latter is best controlled by attaching the substrate to an electric motor with a withdrawal speed of between 0.2 and 10 mm/s. 

The indirect exposure to PFCAs through ingestion of chemicals applied to food contact paper packaging was investigated by D eon and Mabury [146]. In this study, the load of PFCAs in rats was quantified following exposure to polyfluoroalkyl phosphate surfactants (PAPS), a class of nonpolymeric PFCs approved for application to food contact paper products. Increased levels of PFOA were observed in the dosed animals, linking ingestion of PAPS with in vivo production of perfluorinated acids [146]. 

Yamashita, N., Kannan, K., Taniyasu, S., Horii, Y, Okazawa, T., Petrick, G., et al. Analysis of perfluorinated acids at parts-per-quadriUion levels in seawater using liquid chromatography-tandem mass spectrometry. Environ. Sci. TechnoL, 38 5522-5528 (2004). 

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