Fluorine‐Containing Polymers, Perfluoroalkanesulfonic Acids

Abstract

Perfluoroalkanesulfonic acids and their derivatives are of commercial significance because of their unusual acid strength, chemical stability, and the surface activity of the higher members of the series (eight carbons and larger). The best method of preparation is via the perfluorinated sulfonyl fluorides derived from electrochemical fluorination, although other methods including direct fluorination with fluorine gas are known. The first member of the series, trifluoromethanesulfonic acid, is one of the strongest acids known. Alkyl esters of trifluoromethanesulfonic acid are among the best leaving groups known and are commonly used in that capacity in displacement reactions. Lithium trifluoromethanesulfonate solutions are very conductive and can find application as electrolytes in primary lithium batteries and as antistats for films. Derivatives of the longer‐chain perfluoroalkanesulfonic acids have a number of unique surface‐active properties and have formed a basis for a number of commercial products. The longer‐chain acids and their salts, particularly C 8 F 17 SO 3 H and higher, are surface‐active agents in aqueous media. They reduce the surface tension of water to levels not possible with hydrocarbon surfactants. Preparation of difunctional perfluoroalkanesulfonates and their derivatives is discussed, including fluorosulfonylacetyl fluoride. Fluorosulfonyldifluoracetyl fluoride is an important industrial intermediate used in the production of Du Pont's Nafion ion‐exchange membranes and in many other applications.

Toxicological profile for perfluoroalkyls

“…Perfluoroalkyls been manufactured industrially by electrochemical fluorination (ECF), fluorotelomer iodide oxidation, fluorotelomer olefin oxidation, and fluorotelomer iodide carboxylation (Prevedouros et al 2006;Schultz et al 2003). During the ECF process, an organic acyl or sulfonyl fluoride backbone structure is dissolved in a solution of aqueous hydrogen fluoride (Savu 1994b;Siegemund et al 2005). A direct electrical current is then passed through the solution, which replaces all of the hydrogens on the molecule with fluorines.…”

“…Perfluoroalkanesulfonyl fluorides produced by ECF are hydrolyzed under alkaline conditions to form the corresponding salt (Savu 1994b;Siegemund et al 2005). Acidification followed by distillation yields the anhydrous perfluoroalkanesulfonic acid.…”

Predicting risks in an increasingly complex world

“…Perfluoroalkyls have been manufactured industrially by electrochemical fluorination (ECF), fluorotelomer iodide oxidation, fluorotelomer olefin oxidation, and fluorotelomer iodide carboxylation (Prevedouros et al 2006;Schultz et al 2003). During the ECF process, an organic acyl or sulfonyl fluoride backbone structure is dissolved in a solution of aqueous hydrogen fluoride (Savu 1994b;Siegemund et al 2005). A direct electrical current is then passed through the solution, which replaces all of the hydrogens on the molecule with fluorines.…”

“…R hCOF + HF RfCOF + H2 + byproducts RfCOF + H2O RfCOOH + HF Perfluoroalkanesulfonyl fluorides produced by ECF are hydrolyzed under alkaline conditions to form the corresponding salt (Savu 1994b;Siegemund et al 2005). Acidification followed by distillation yields the anhydrous perfluoroalkanesulfonic acid.…”

An overview of the uses of per- and polyfluoroalkyl substances (PFAS)

“…[23][24][25][26][27][28][29] Reports and books that address fluorosurfactants and fluoropolymers in general were also included. 3,8,12,16,20,21,[32][33][34][35][36][37][38][39][40][41][42][43] Literature specific to certain use categories was retrieved for more information either on the substances used, or to understand why PFAS are, or were, necessary for a given use. All specific references are cited in the Electronic Supplementary Information 1 (ESI-1).…”