Perfluoroalkanesulfonic acid

PerfluoroaLkanesulfonic acids and thek derivatives are of commercial significance because of thek unusual acid strength, chemical stabiUty, and the surface activity of the higher members of the series (eight carbons and larger). 

The perfluoroalkane sulfonic acids were fkst reported ki 1954. Trifluoromethanesulfonic acid was obtained by the oxidation of bis(ttifluoromethyl thio) mercury with aqueous hydrogen peroxide (1). The preparation of a series of perfluoroalkanesulfonic acids derived from electrochemical fluotination (ECF) of alkane sulfonyl haUdes was also disclosed ki the same year (2). The synthetic operations employed when the perfluoroalkanesulfonic acid is derived from electrochemical fluotination, which is the best method of preparation, are shown ki equations 1—3. 

Perfluorosulfonyl fluorides can also be prepared by the electrochemical fluotination of saturated or unsaturated cycHc sulfones (3—5). Perfluorobutanesulfonyl fluoride can be prepared ki 40—48% yield from sulfolane (eq. 4) (6). 

Yields of sulfonyl fluorides prepared by ECF vary depending on the particular stmcture. Chain degradation becomes more important as the chain length kicreases (6). Yields can vary from 96% for perfluoromethanesulfonyl fluoride (7) to 43—50% for perfluorooctanesulfonyl fluoride (8). Trifluoromethanesulfonic acid can be prepared via trifluoromethanesulfenyl chloride as shown ki equations 5—7 (9). 

Other preparations of trifluoromethanesulfonic acid kiclude oxidation of methyltrifluoromethyl sulfide under a variety of conditions (10,11). Perfluorosulfonyl fluorides have also been prepared by reaction of fluoroolefkis with sulfuryl fluoride (12,13). Chinese chemists have pubflshed numerous papers on the conversion of telomer-based alkyl iodides to sulfonyl fluorides (14,15) (eqs. 8 and 9)  

Perfluoroalkanesulfonic Acids. Perfluoroalkanesulfonic acids were first reported in 195616 and subsequently have been prepared by electrochemical fluorination (ECF) of the corresponding alkanesulfonyl halides and subsequent hydrolysis17-19 [Eq. (2.8)]. The boiling points, density, and //0 values of these acids are compared in Table 2.2. 

Trifluoromethanesulfonic Acid. Trifluoromethanesulfonic acid (CF3SO3H, triflic acid), the first member in the perfluoroalkanesulfonic acid series, has been studied extensively, and excellent reviews describing its physical and chemical properties have been published.18,19 Besides its preparation by electrochemical fluorination of methanesulfonyl halides,20 triflic acid may also be prepared from 

In 2000, Rhodia began the production of triflic acid by a new process, which includes sulfination of potassium trifluoroacetate, oxidation of the resulting potassium triflinate, followed by acidification and purification23 [Eq. (2.11)]. 

Extreme care should be taken while handling the perfluoroalkanesulfonic acids. Studies suggest that extreme irritation and permanent eye damage could occur following eye contact, even if the eyes are flushed immediately with water. Acute inhalation toxicity studies (in albino rats) indicate that high vapor or mist concentrations can cause significant respiratory irritation. All contacts of the acids and their esters with the skin should be avoided. Usual procedures for treatment of strong acid bums should be applied. 

Contact of the perfluoroalkanesulfonic acids with cork, mbber, cellulose, and plasticized materials will cause discoloration and deterioration of these materials. Samples are best stored in glass ampoules or glass bottles with Kel-For Teflon plastic screw-cap linings. 

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Fluotinated higher carboxyHc acids, Perfluoroalkanesulfonic acids,... 

The boiling pokits of a series of perfluoroalkanesulfonic acids are Hsted ki Table 1 (2). 

The longer perfluoroalkanesulfonic acids are hydroscopic oily Hquids. Distillation of the acid from a mixture of its salt and sulfuric acid gives a hydrated mixture with melting points above 100°C. These acids show the same general solubiUties as trifluoromethanesulfonic acid, but are insoluble in ben2ene, heptane, carbon tetrachloride, and perfluorinated Hquids. AH of the higher perfluoroalkanesulfonic acids have been prepared by electrochemical fluorination (20). 

Perfluoroacylbenzene sulfonates, 12 174 Perfluoroacyl fluorides, 11 865 alkylation of, 11 883 Perfluoroalkanesulfonic acids, 12 191 Perfluoroalkoxy (PFA) fluorocarbon resins, 18 329... 

Tetrakis(perfluoroalkanesulfonates) Zr(RFS03)4 (RF = CF3 or C2F5) have been prepared by reaction of ZrCl4 with an excess of the perfluoroalkanesulfonic acid.467 Hie mode of attachment of the perfluoroalkanesulfonate ligands is unknown. 

Palladium complexes exhibit even higher catalytic activity and produce branched acids preferentially.132 133 The selectivity, however, can be shifted to the formation of linear acids by increasing the phosphine concentration.134 Temperature, catalyst concentration, and solvent may also affect the isomer ratio.135 Marked increase in selectivity was achieved by the addition of Group IVB metal halides to palladium136 and platinum complexes.137 Linear acids may be prepared with selectivities up to 99% in this way. The formic acid-Pd(OAc)2-l,4-bis(diphe-nylphosphino)butane system has been found to exhibit similar regioselectivities.138 Significant enhancements of catalytic activity of palladium complexes in car-bomethoxylation by use of perfluoroalkanesulfonic acid resin cocatalysts was reported.139,140... 

FLUORINECOMPOUNDS,ORGANIC - PERFLUOROALKANESULFONIC ACIDS] (Vol 11) 3-fluoro-chloramphemcol [73212-55-2]... 

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