Perfluoroalkyl sulfonic acids/sulfonates

Arylsulfmic acids are perfluoroalkylated under the conditions, but the yield IS low [77 (equation 70) The isolated product is an aryl perfluoroalkyl sulfone. The possible formation of a perfluoroalkyl aryl sulfinate intermediate, arising from an 0-alkylation reachon, has not been discussed. 

Generally, treatment with electron-deficient olefins such as nitroethylene or vinyl sulfone is effective for radical addition reactions, since alkyl radicals derived from O-acyl esters (2) are nucleophilic and take SOMO-LUMO interaction. However, treatment of O-acyl esters ) derived from perfluoroalkyl carboxylic acids (RfC02H) generates electrophilic radicals, Rf, which react preferably with electron-rich olefins such as vinyl ether, as shown in eq. 8.16 [52]. 

Also under development is use of the alternative feedstock, toluene, for PTA and/or DMT production. Carbonylation of toluene to produce p-tolualdehyde was shown to proceed in 90-95% yield when catalyzed by HF BF3 [31], or by higher perfluoroalkyl sulfonic acids [32], or in greater than 99% yield when catalyzed by trifloromethanesulfonic acid [33]. The p-tolualdehyde, which is regularly an intermediate in both the Witten DMT and Amoco TPA processes (see Schemes 2 and 3, respectively), can then be readily oxidized with minimal changes to the oxidation process. 

The development of new polymeric materials for polymer electrolyte fuel cell is one of the most active research areas, aiming at the new energy sources for electric cars and other devices. The mainstream of the material research for fuel cell is perfluoroalkyl sulfonic acid membranes such as Nafion, Acipex, and Flemion. The most well-known one is Nafion of Du Pont, which is derived from copolymers of tetrafluoro-ethylene and perfluorovinyl ether terminated by a sulfonic acid group.Protons, when dissociated from the sulfonic acid groups in aqueous environment, become mobile and the membrane becomes a proton conducting electrolyte membrane. 

C11-14-branched alkyl acetate CIS-rich. See Oxo-dodecyl acetate C9-C10 alkanes, perfluoro-, sulfonic acid, ammonium salts. See Ammonium C9-10 perfluoroalkyl sulfonate... 

Poly(phenylene ether) s with pendant perfluoroalkyl sulfonic acids with an ion exchange capacity of 1.17-1.83 equivalents/g have been synthesized by an aromatic nucleophilic substitution reaction of a perfluo-romonomer, such as decafluorobiphenyl or hexafluo-robenzene with 2,5-bis(4 -iodophenyl)hydroquinone, followed by a Ullman coupling reaction with potassium 1,1,2,2-tetrafluoro-2-(l, 1,2,2-tetrafluoro-2-iodoethoxy)ethanesulfonate [100]. 

Nakabayashi K, Higashihara T, Ueda M. Polymer electrolyte membranes based on poly-(phenylene ether)s with pendant perfluoroalkyl sulfonic acids. Macromolecules 2011 44(6) 1603-9. 

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). 

Qiu, Y, He, J., and Shi, H. 2010. Perfluorocarboxylic acids (PFCAs) and perfluoroalkyl sulfonates (PFASs) in surface and tap water around Lake Taihu in China. Front. Environ. 

Vestergren, R., UUah, S., Cousins, I. T., and Berger, U. 2012. A matrix effect-free method for reliable quantification of perfluoroalkyl carboxylic acids and perfluoroal-kane sulfonic acids at low parts per ttilhon levels in dietary samples. J. Chromatogr. A 1237 64-71. 

Abstract Fluorinated surfactants have been conunercially available since the 1950s. The first available were perfluoroalkyl sulfonic acids. The unique properties e.g., surface tension lowering in aqueous systems, high chemical and thermal stability of these acids and their derivatives when used at low concentrations resulted in their widespread use in industrial processes and consumer uses. The most common commercially produced peifluorinated surfactants are the perfluoroalkyl acids. 

PFSA Perfluoroalkyl sulfonic acid PHxSF perfluorohexane sulfonyl fluoride POSF Perfluorooctane sulfonyl fluoride... 

Rayne S, Forest K (2009) Perfluoroalkyl sulfonic and carboxylic acids A critical review of physicochemical properties, levels and patterns in waters and wastewaters, and treatment methods. J Environ Sci Health A Tox Hazard Subst Environ Eng 44 1145-1199... 

Scheme 2.50 Structures of poly(phenylene ether)s with pendant perfluoroalkyl sulfonic acid groups. Taken from Ref. [183],...

K. Yoshimura, K. Iwasaki, Aromatic polymer with pendant perfluoroalkyl sulfonic acid for fuel cell applications. Macromolecules 42 (23) (2009)9302-9306. 

Water and oil repellent finishes, normally perfluoroalkyl sulfonate (PFAS) and perfluorooctane sulfonate (PFOS), are not to be used, and their threshold limit is 1 pg/m each in the coated material whereas all other PFAS forms, the threshold limit is 20 pg/kg and MSDS is required to be supplied for verification. The test method is based on solvent extraction and GC-MS or HPLC-MS. For per fluoro carboxylic acids and salts (PFCA), the limiting value is 0.05 ppm or sum total is 0.1 ppm. 

Chem. Descrip. Salt of perfluoroalkyl sulfonic acid Ionic Nature Anionic... 

SPES with Pendant Perfluoroalkyl Sulfonic Acids.179... 

Many research studies have focused on improving the nanophase-separated structures between the hydrophilic and hydrophobic units to increase the proton conductivity of the aromatic ionomers under low RH. In this section, recent approaches to improve the membrane properties, especially the proton conductivity, which is usually the first characteristic considered when evaluating membranes for fuel cells, and morphology will be discussed as follows (1) multiblock SPES copolymers, (2) locally and densely SPES, (3) SPES with high lEC values and high free volume, (4) SPES with pendant perfluoroalkyl sulfonic acids, (5) cross-linked SPES, and (6) thermally annealed SPESs. 

Another approach to improve the performance of the aromatic PEMs as well as high lEC values is the introduction of perfluoroalkyl sulfonic acids in place of the normal sulfonic acids. Compared to the acidity of the sulfonated aromatic polymers... 

Despite its higher lEC values, the proton conductivity of the membranes was lower than that of the Nafion membrane. The authors concluded that acidity was a crucial factor to determine the proton conducting properties. However, other structural factors, such as the hydrophobicity and flexibility of the main chain, would have to be optimized for further improving the proton conductivity of the aromatic ionomer membranes [51]. On the other hand, Ueda and coworkers reported a novel PES containing binaphthyl units with pendant perfluoroalkyl sulfonic acids (BNSH-PSA) for PEM [52]. The BNSH-PSA (1EC=1.91 meq./g) was prepared by the aromatic nucleophilic substitution reaction of l,T-binaphthyl-4,4 -diol and 4,4 -dichlorodiphe-nylsulfone, followed by bromination with bromine, and then the Ullmann coupling reaction with PSA-K (Scheme 4.19). 

The BNSH-PSA membrane with highly acidic perfluoroalkyl sulfonic acids prepared by solution casting showed a high oxidative and dimensional stability. It also produced a high proton conductivity comparable to the Nafion 117 membrane in the range of 30%-95% RH, regardless of the moderate lEC value (1.91 meq./g) (Figure 4.45). Furthermore, AFM observation supported the formation of the phase-separated structure in which the hydrophilic domains were well dispersed and connected to each other. 

Nakagawa, T, Nakabayashi, K., Higashihara, T., and Ueda, M. 2011. Polymer electrolyte membrane based on poly(ether sulfone) containing binaphthyl units with pendant perfluoroalkyl sulfonic acids. J. Polym. Sci. A Polym. Chem. 49 2997-3003. 

Recently, an interesting modified postsulfonation procedure was developed by He et al. to prepare a series of perfluoroalkyl sulfonic acid-functionalized polyphosphazenes (PSA-P) [94]. A polymer precursor, poly[(4-bromophenoxy) (phenoxy)phosphazene], was synthesized first before reacting with potassium... 

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