Perfluorinated applications

Bergbreiter DE, Li J (2004) Applications of Catalysts on Soluble Supports. 242 113-176 Bertrand G, Bourissou D (2002) Diphosphorus-Containing Unsaturated Three-Menbered Rings Comparison of Carbon, Nitrogen, and Phosphorus Chemistry. 220 1-25 Betzemeier B, Knochel P (1999) Perfluorinated Solvents - a Novel Reaction Medium in Organic Chemistry. 206 61-78 Bibette J,see SchmittV (2003) 227 195-215... 

Du Font s Nafion membranes have been the first truly successful membranes in these applications. They are made of a perfluorinated and sulfonated polyal-kylene ionomer (-CFj- or >CF- throughout). Such a composition leads to... 

The strategy of using two phases, one of which is an aqueous phase, has now been extended to fluorous . systems where perfluorinated solvents are used which are immiscible with many organic reactants nonaqueous ionic liquids have also been considered. Thus, toluene and fluorosolvents form two phases at room temperature but are soluble at 64 °C, and therefore,. solvent separation becomes easy (Klement et ai, 1997). For hydrogenation and oxo reactions, however, these systems are unlikely to compete with two-phase systems involving an aqueous pha.se. Recent work of Richier et al. (2000) refers to high rates of hydrogenation of alkenes with fluoro versions of Wilkinson s catalyst. De Wolf et al. (1999) have discussed the application and potential of fluorous phase separation techniques for soluble catalysts. 

The evaluation for aquatic toxicity on daphnids and fish is reported in Tables 12 and 13. Bold values indicate that compounds are out of the model applicability domain (ECOSAR) or that the prediction is not reliable. ECOSAR and ToxSuite are able to predict all the selected compounds while T.E.S.T. fails in prediction for the daphnia toxicity of perfluorinated compounds (PFOS and PFOA). Tables 12 and 13 include also a limited number of experimental results provided by the model training dataset (some data are extracted from USEPA Ecotox database). Predicted results are in agreement for five compounds only (2, 3, 5, 13 and 14) for both endpoints while the predictions for the other compounds are highly variable. 

FEP polymer, 10 220 18 306—307. See also Fluorinated ethylene propylene (FEP) Perfluorinated ethylene-propylene (FEP) copolymers applications of, 18 315—316 chemical properties of, 18 313 dispersion processing of, 18 314 economic aspects of, 18 315 effects of fabrication on properties of, 18 315... 

Under RP-Cis column separation conditions, no differentiation between conventional AE and fluorinated AE in retardation behaviour could be observed. The application of a perfluorinated RP-C8 column to a mixture of standards of non-ionic fluorinated surfactants and the extracts of wastewater sludges spiked with these compounds using realistic concentrations, however, resulted in good separation of AE and fluorinated AE (cf. mass traces and TIC in Fig. 2.9.46(a), (b) or (e) and Fig. 2.9.46(c), (d) or (e), respectively) or matrix and fluorinated AE surfactants (Fig. 2.9.46(f), (g) or (h), respectively) [52]. 

Dolye, M. and Rajendran, G. 2003. Perfluorinated membranes. In Handbook of fuel cells—Fundamentals, technology and applications, part 3, ed. W. Vielstich, A. Lamm and H. A. Gasteiger, 351. Colchester, England John Wiley Sons. 

Eisman, G. A. 1990. The applications of Dow GhemicaTs perfluorinated membranes in proton exchange membrane fuel cells. Journal of Power Sources 29 389-398. 

Another approach to isolate the catalyst from the products is the application of perfluorinated catalytic systems, dissolved in fluorinated media [63], which are not non-miscible with the products and some commonly used solvents for catalysis like THE or toluene at ambient temperature. Typical fluorinated media include perfluorinated alkanes, trialkylamines and dialkylethers. These systems are able to switch their solubility properties for organic and organometallic compounds based on changes of the solvation ability of the solvent by moving to higher temperatures. This behavior is similar to the above-mentioned thermomorphic multiphasic PEG-modified systems [65-67]. 

An important step towards a possible application of these compounds in technical syntheses of chemicals was the successful demonstration of a ther-momorphic reversible immobihzation of perfluorinated catalysts on teflon or other solid fluorous matrices, which might be practiced in industrial low-scale applications, e.g., of pharmaceutical intermediates in the case of quantitative recovery of the organometalHc compound. The facile separation due to their physicochemical behavior and the constant good performance in coupHng reactions of the involved perfluorinated pincer complex makes this system attractive for further investigations. 

On the basis of their previous experiences with lithium borates coordinated by substituted ligands. Barthel and co-workers modified the chelatophos-phate anion by placing various numbers of fluorines on the aromatic ligands. Table 13 lists these modified salts and their major physical properties. As expected, the introduction of the electron-with-drawing fluorines did promote the salt dissociation and reduce the basicity of phosphate anion, resulting in increased ion conductivity and anodic stability. The phosphate with the perfluorinated aromatic ligands showed an anodic decomposition limit of 4.3 V on Pt in EC/DEC solution. So far. these modified lithium phosphates have attracted only academic interest, and their future in lithium ion cell applications remains to be determined by more detailed studies. 

Palladium(ll) complexes of imidazolin-2-ylidenes bearing perfluorinated side chains 46 were prepared and suggested to be useful in flourous biphasic catalysis as well as in supercritical C02. ° However, catalytic applications have not been reported yet. 

The perfluoroacetamide catalysts, rhodium(II) trifluoroacetamidate [Rh2(tfm)4] and rhodium(II) perfluorobutyramidate [Rh2(pfbm)4], are interesting hybrid molecules that combine the features of the amidate and perfluorinated ligands. In early studies, these catalysts were shown to prefer insertion over cycloaddition [30]. They also demonstrated a preference for oxindole formation via aromatic C-H insertion [31], even over other potential reactions [86]. In still another example, rhodium(II) perfluorobutyramidate showed a preference for aromatic C-H insertion over pyridinium ylide formation, in the synthesis of an indole nucleus [32]. Despite this demonstrated propensity for aromatic insertion, the perfluorobutyramidate was shown to be an efficient catalyst for the generation of isomtinchnones [33]. The chemoselectivity of this catalyst was further demonstrated in the cycloaddition with ethyl vinyl ethers [87] and its application to diversity-oriented synthesis [88]. However, it was demonstrated that while diazo imides do form isomtinchnones under these conditions, the selectivity was completely reversed from that observed with rhodium(II) acetate [89, 90]. 

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