Perfluoroalkanesulphonic acids acidity

Trifluoromethanesulphonic acid is commercially available and is the most readily obtained member of this series by electrochemical fluorination [202-205] (Figure 8.68), since the yields of perfluoroalkanesulphonic acids decrease as the size of the alkyl group increases. 

Straight-chain perfluoroalkanoic or perfluoroalkanesulphonic acids fluorides derived by electrofluorination can be subjected to hydrolysis, esterification, amidation and other modifying, as illustrated with the following reactions [124, 126] ... 

T. Gramstad, R. N. Haszeldine, J. Chem. Soc. 1956, 173-180. Perfluoroalkyl derivatives of sulphur. Part IV. Perfluoroalkanesulphonic acids. 

Perfluoroalkanesulphonic Acids and Related Compounds. Continued industrial interest in this area of fluorocarbon chemistry has ensured a steady flow of patent literature relevant to this Report, some of which has been included in a list at the end of this chapter (p. 287). 

Perfluoroalkanesulphonic Acids and Related Compounds. In addition to work on the electrochemical fluorination of sulphones noted earlier (see above), application of this technique to sulpholene and 3-methylsulpholene, respectively, has been shown to yield perfluorobutane-l-sulphonyl fluoride and a mixture of the isomers CFs-(CF2)4S02F, (CF3)2CF-(CF2)2 S02F, and CFs CF2 CF(CF,)-CFj S02F. The preparation of perfluoropropane-2-sulphonyl fluoride via the carbanion route, using perfluoropropene. 

Anodic oxidation of iodoperfluoroalkanes in the presence of perfluorosulphonic acids leads to the production of perfluoroalkyl perfluoroalkanesulphonate esters in good yields393. 

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