500. Fluorinated sulphonic acids. Part I. Perfluoro-methane-, -octane-, and -decane-sulphonic acids and their simple derivatives

Abstract

Periluoro-methane-, -%-octane-, and -%-decane-sulphonyl fluoride were prepared from alkanesulphonyl chlorides by electrochemical fluorination. Various derivatives of the fluorocarbonsulphonic acids were made. The long-chain acids were highly surface-active.RECENT patents assigned to the Minnesota Mining and Manufacturing Company on the preparation of perfluoroalkanesulphonyl fluorides prompt us to publish some of our preliminary, very similar, results. The present paper describes the preparation, by the well-known electrochemical procedure of Simons ,2 of perfluoro-methane-, +octane-, and -n-decane-sulphonyl fluoride from the corresponding alkanesulphonyl chloride (which was made from the alkyl bromide via the sodium alkanesulphonate). The acid fluorides were then converted into simple derivatives of the fluorocarbonsulphonic acids.Trifluoromethanesulphonyl fluoride was obtained in 50-60% yield (cf. Gramstad and Haszeldine 3). Yields of perfluoro-n-octane-and -1.2-decane-sulphonyl fluoride were lower (12-15%) and large amounts of sulphur-free material, probably perfluoro-n-octane and perfluoro-n-decane, were obtained, together with smaller amounts of shorter-chain fluorocarbons and some polymeric residue. It appeared that the chlorine atoms of the sulphonyl chlorides were displaced electrolytically, since no apparent reaction took place with anhydrous hydrofluoric acid alone but a chlorine-containing gas was obtained during the fluorination of methanesulphonyl chloride. The yields of the fluorocarbonsulphonyl fluorides could probably be increased by more detailed individual studies.Various salts were prepared from these acid fluorides by treatment with the appropriate aqueous metal hydroxide. The sodium and potassium salts of the C, and C, , acids were almost insoluble in water. However, though salts of strong acids, they were rather more soluble in ethanol than in the more highly ionising solvent, water. They differed from the corresponding perfluorocarboxylates in their much greater thermal stabilities. They melted below 330", and were stable for long periods at 300" but decomposed in air at 350" (over a period of days) with the formation of sulphate ion : perfluorocarboxylic salts, on the other hand, decompose rapidly at about 250" to give 01efin.s.~The free C, acid 5* formed a hydrate sufficiently stable to be distilled from concentrated sulphuric acid. With phosphoric oxide the anhydrous acid gave the anhydride which decomposed partly after a few days, sulphur dioxide being evolved.The C, and C,, acids were not isolated completely pure by distillation of mixtures of their salts with sulphuric acid because of their somewhat comparable volatilities. An aqueous solution of the C,, acid was prepared by treatment of a saturated solution of the sodium salt with an ion-exchange resin (Zeo-Karb 225). The free acid was converted, in sit%, into its anilinium salt. An attempt to hydrolyse the C, sulphonyl fluoride with water at 160" for 60 hr. failed, no reaction taking place. Under milder conditions however, the C, fl...

Perfluoroalkanesulfonylimides and their lithium salts: synthesis and characterisation of intermediates and target compounds

“…NLi 59 Table 6 Ionic conductivity of perfluorinated lithium bis(perfluoroalkanesulfonyl)imides, CF 3 SO 3 Li and LiPF 6 cell was charged, under nitrogen 12 l/h flow, with CH 3 SO 2 F (410 g; 4.18 mol) during 5 days, the ECF process was runned at 5.3-5.5 V and 6.4-7.3 A. At the end of the fluorination the liquid inside the cell appeared colourless.…”

“…In particular, the ECF obtainment of perfluoroalkanesulfonylfluorides has been intensively investigated [5][6][7][8][9]12], with some contributions by Fluorine Chemistry Laboratory of Padua University [10,11].…”

Hydrotrope‐Induced Enhancement of Room Temperature Surface Activity for High Krafft Point Fluorinated Surfactants

“…Potassium perfluorooctane sulfonate (KPFOS, 98 %) and sodium perfluorooctane sulfonate (NaPFOS, 98 %) are products from Beijing FLUOBON Surfactant Institute. The two surfactants were synthesized from perfluorooctanesulfonyl fluoride (98 %, Aldrich) and KOH/NaOH in aqueous solution and were then filtered and purified [17,18]. Sodium p-methylbenzene sulfonate (BS, Acros) and urea (Beijing Chemical Works, AR grade) are purchased and used as received.…”

Functional Compounds Containing Oxygen, Sulphur or Nitrogen and their Derivatives

“…Also, intermediate peroxides are formed in the oxidation of perfluorinated alkenes, e.g. [5,7,200,201] A Perfluoroalkanesulphonic acids Trifluoromethanesulphonic acid is commercially available and is the most readily obtained member of this series by electrochemical fluorination [202][203][204][205] (Figure 8.68), since the yields of perfluoroalkanesulphonic acids decrease as the size of the alkyl group increases. [5,7,200,201] A Perfluoroalkanesulphonic acids Trifluoromethanesulphonic acid is commercially available and is the most readily obtained member of this series by electrochemical fluorination [202][203][204][205] (Figure 8.68), since the yields of perfluoroalkanesulphonic acids decrease as the size of the alkyl group increases.…”

“…Triflate salts are important catalysts because the anions are poorly co-ordinating [214,215] (Figure 8.71 Trifluoromethanesulphonic acid forms a very stable crystalline hydrate [205,218] and reacts vigorously with alcohols, ethers and ketones. Oxonium salts are formed and further reaction may occur on heating (Figure 8.73).…”