Fluorinated Higher Carboxylic Acids

Abstract

Perfluorinated carboxylic acids are corrosive liquids or solids. The acids are completely ionized in water. The acids are of commercial significance because of their unusual acid strength, chemical stability, high surface activity, and salt solubility characteristics. The higher members of the series have the property of decreasing the surface tension of aqueous solutions well below the point possible with any type of hydrocarbon surfactant. There are five methods for the preparation of long‐chain perfluorinated carboxylic acids and derivatives: electrochemical fluorination, direct fluorination, telomerization of tetrafluoroethylene, oligomerization of hexafluoropropylene oxide, and photooxidation of tetrafluoroethylene and hexafluoropropylene. In general, the reactions of the perfluoroacids are similar to those of the hydrocarbon acids, although in some cases the electronegativity of the perfluoroalkyl groups make formation of certain derivatives easier or harder. A general summary of formation and properties of the derivatives of perfluorinated acids is discussed. Data on the fluorinated dicarboxylic acids and their derivatives are also summarized.

Predicting risks in an increasingly complex world

“…The fluorotelomer iodide oxidation process was developed by DuPont and has served as the basis for their fluoropolymer production chemistry (Buck et al 2011;Hekster et al 2003;Savu 1994a;Siegemund et al 2005). It begins with the preparation of pentafluoroiodoethane from tetrafluoroethene.…”

Reply to Comment on “Highly Selective Removal of Perfluorinated Contaminants by Adsorption on All‐Silica Zeolite Beta”

“…So far we have focused on linear compounds like PFOAorPFOS,which fit well even in the linear sections of the *BEA channels.H owever,t he intersections of the 12-membered ring *BEA channels are significantly more spacious,a nd could easily accommodate even branched perfluorinated compounds.T he latter are less important than linear compounds:w hile indeed the electrochemical Simons fluorination may produce am inor fraction ( % 20 %) of branched isomers alongside linear ones (80 %), the products are often further purified, and alternative,more recent production techniques,based on for example,telomerisation of tetrafluoroethene,d on ot generate branching. [9] Nevertheless,a snewm olecules,i ncluding degradation products of fluoropolymers come into focus,t here will be an eed for rationally designed alternative adsorbents;and the case of all-silica Beta sets the scene for use of other all-silica zeolites with even more spacious topologies (IWV,Y FI, UTL…). [10] Whenever using microporous materials,d iffusion limitation may come into play.A ll-silica zeolites synthesized with F À as am ineralizer are not only much more defect free than materials synthesized with OH À ;t hey often grow into significantly larger crystals,d ue to the dissolution of small nuclei.…”