Polyfluorinated anions

Polyfluoroalkylation Some of the chemistry of polyfluoroalkyl anions, generated by reaction of fluoroalkenes with fluoride ion, was discussed in Chapter 7, where the analogy between the role of fluoride ion in fluorocarbon chemistry and the role of the proton in hydrocarbon chemistry was emphasised. This analogy has been extended to include reactions of polyfluorinated anions, generated in the same way, with activated poly-fluoro-aromatic systems in what may be regarded as the nucleophilic counterpart of Friedel-Crafts reactions [119] (Figure 9.50). 

Large Polyfluorinated Anions Used To Generate Coordinative Unsaturation in Cations... 

A1(0CH2CF3)3, polymerization of fluorinated aldehyde, 214 Anion(s), polyfluorinated. See Polyfluorinated anions Anion basicity scale, dimethyltin(IV) cation, 352-354... 

Generation of electrophilic species from organic polyfluorinated materials usually requires direct interaction of a strong Lewis acid with a substrate, which can result in formation of a cation either by abstraction of a halogen anion (usually F ) from a substrate (Eq. 8) or by formation of a zwitterionic intermediate as a result of coordination of the Lewis acid with an unshared electron pair on a multiply bonded heteroatom (Eq. 9) [12] ... 

Aliphatic and cyclic polyfluorinated alkencs are readily oxidized by potassium permanganate. Polylluoroalkenes whose C = C bonds are deficient in electrons are readily attacked by the permanganate anion. Depending on the substitution of the C = ( bond, the resulting products are acids or ketones. 

Anions may be generated by reaction of fluoride ion with polyfluorinated aza-alkenes in a manner similar to that described earlier for fluoroalkenes (see Chapter 7, Section IIC, Subsection b) but, not being as readily available as fluoroalkenes, the chemistry is less well developed. Some examples of reactions induced by formation of aza-anions from aza-alkenes are shown in Figure 8.114. 

Chambers, R.D. Philpot, P.D. Russell, PL. Anionic i -complexes from polyfluorinated s-triazines. J. Chem. Soc., Perkin Trans. 1 1977, 1605-1608. 

Polyfluorinated compounds comprise hundreds of chemicals characterized by hydrophobic linear alkyl chains partially or fully fluorinated (as the perfluorinated compounds [PFCs]) and containing different functional groups. Polyfluorinated compounds include perfluoroalkyl sulfonamides (PFASAs), fluorotelomer alcohols (FTOHs), polyfluorinated alkyl phosphates (PFAPs), fluorotelomer unsaturated carboxylic acids (FTUCAs), perfluoroalkyl acids (PFAAs), and their salts. The most common PFAAs are perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFASs). In particular, PFASs contain one or more fluorinated alkyl chains bonded to a polar head, which at neutral pH can be charged (anionic, cationic, and amphiphilic surfactants) or noncharged (nonionic surfactants). 

PFOA, PFOS, and anionic and nonionic polyfluorinated surfactants... 

Trier, X., Granby, K., and Christensen, J. H. 2011. Tools to discover anionic and nonionic polyfluorinated alkyl surfactants by hquid chromatography elechospray ionisation mass spectrometry. J. Chromatogr. A 1218 7094-7104. 

ESI operating in the negative ion (NI) mode has been the interface most widely used for the analysis of anionic polyfluorinated surfactants. In addition, ESI has also been optimized for the determination of neutral compounds such as the sulfonamides PEGS A, Et-PEOSA, and t-Bu-PEOS. The use of atmospheric pressure photoionization (APPI) has been explored in few works [72-74]. Takino et al. [72] fotmd the absence of matrix effects as the main advantage of this technology, but the limits of detection were considerably higher than those obtained by LC-ESI-MS/MS. 

Maayan, G., Fish, R. and Neumann, R. (2003) Polyfluorinated Quaternary Ammonium Salts of Polyoxometalate Anions Fluorous Biphasic Oxidation Catalysis with and without Huorous Solvents, Org. Lett., 5, pp. 3547-3550. 

Nonchain reactions initiated by elechon ttansfer to the aromatic and fragmentation of the radical anion have been reported for good acceptors, e.g., for some polyfluorinated... 

---