Perfluorinated sulfonamides

Shoeib, M., Harner, T., Wilford, B.H., Jones, K.C. and Zhu, J.P. (2005) Perfluorinated sulfonamides in indoor and outdoor air and indoor dust occurrence, partitioning, and human exposure. Environmental Science and Technology, 39, 6599-606. 

These new compounds offer the possibility of less persistance than DDT. Many are quite active. USDA chemists have found that perfluorinated sulfonamides and sulfonates have a delayed action on the fire ant. 

Perfluorinated sulfonamide monomers were prepared by DesMarteau. A typical synthetic scheme is given in Fig. 16 [39,40]. The temperature dependency and humidity dependency of proton conductivity of the sulfonamide copolymer with TFE were examined, and the properties were proved to be similar to those of a sulfonic acid type membrane [41-43]. Fuel cell performance was dependent upon membrane thickness and/or lEC, and there do not seem to be large differences depending on the species of the ion-exchange groups. Synthesis of a short side chain type sulfonimide monomer is also reported (see Fig. 17 [44]). 

Fig. 16 Typical synthetic scheme for the perfluorinated sulfonamide monomers...

Chu S, Letcher RJ (2008) Analysis of fluorotelomer alcohols and perfluorinated sulfonamides in biotic samples by liquid chromatography-atmospheric pressure photoionization mass spectrometry. J Chromatogr A 1215 92-99... 

ESI operating in the negative ion mode has been the interface most widely used for the analysis of anionic perfluorinated surfactants. In addition, ESI has also been optimized for the determination of neutral compounds such as the sulfonamides perfluorooctanesulfonamide (PFOSA), perfluorooctanesulfonami-doacetate (A-EtFOSAA), and t-Bu-PFOS. The use of APPI has been explored in few works [126-128], Takino et al. [126] found as the main advantage of this technology, the absence of matrix effects, but the LODs were considerably higher than those obtained by LC-ESI-MS-MS. 

Keywords Perfluorinated acid Precursors Perfluorooctane sulfonamides ... 

Perfluoroalkyl acids (PFAs) are synthetic, perfluorinated, straight- or bran-ched-chain organic acids characterized by a carboxylate or sulfonate moiety [1]. PFAs are manufactured directly but can also be formed through transformation of many precursor molecules containing a perfluoroalkyl moiety [2], These include fluorotelomer alcohols (FTOHs) and perfluoroalkyl-sulfonamides (Table 1, Fig. 1), however, others likely exist. Collectively, this family of chemicals including PFAs and their polyfluorinated precursors will be referred to in this document as perfluoroalkyl substances (PFSs). 

A good measure of past and continuing interest in ionomer membranes issued from the development of perfluorinated ionomers, the first-announced being Nafion(44). These materials are characterized by remarkable chemical resistance, thermal stability and mechanical strength, and they have a very strong acid strength, even in the carboxylic acid form. The functionalities that have been considered include carboxylate, sulfonate, and sulfonamide, the latter resulting from the reactions of amines with the sulfonyl fluoride precursor. 

Since the conductivity of electrolytes and the cross section and thickness of the membrane are known, a can be determined from the voltage drops across the three pairs of probe electrodes 1-2, 3-4 and 5-6. The sodium current efficiency (CE) can also be determined by titrating the amount of caustic soda generated over a given period of time. The confinement chambers around the working electrodes are used to eliminate free bubbles near the membrane. Our normalized transport data for sulfonate, carboxylate and sulfonamide ionomers are plotted In Figure 5 the universal percolative nature of perfluorinated ionomers can be clearly eeij. The prefactor sulfonate ionomers. The exponent t is 1.5 0.1 in reasonable agreement with theory and the thresholds are between 8 to 10 vol. %, which are consistent with the bimodal distribution in cluster size postulated by the cluster-network model (5.18). This theory has also been applied recently to delineate sodium selectivity of perfluorinated ionomers (20). 

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). 

There seems to be a number of other candidates suitable as a third comonomer (e.g., trilluorovinyl monomers containing phosphonic acid, sulfonamide, sulfraiimide, and/or cross-linkable moieties) [8-12], however, high production cost of these rather complex perfluorinated vinyl compounds may be an obstacle to the practical industrial applications. 

PFOS and related perfluorinated compounds have been found in many organisms around the world. Generally, they are found in the highest amounts in the tissues of predators at the top of the food chain, which have fish as the major food component. In addition to PFOS, perfluorooctane sulfonamide (PFOSA) is usually present, one of the precursors of PFOS. In fish there are often higher PFOSA concentrations than PFOS concentrations, whereas in mammals the opposite is true. This may indicate that mammals have metabolic apparatus that can metabolise PFOSA to PFOS. 

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