Physical and Chemical Properties of a New Series of Carboxylic Acids, Cl (CF₂CFCl)_xCF₂CO₂H.

Abstract

T he announcement of the electrochemical fluorination process in 1949 (6) has made available, or potentially so, a whole series of perfluorinated alkanoic acids. Somewhat later, Berry (2) described a process for converting , ,trihydroperfluoro alcohols into the corresponding -hydroperfluoro acids. This process, which utilizes liquid polymers of tetrafluoroethylene, is limited to -hydroperfluoro acids having an odd number of carbon atoms. In this article a new series of perhalogenated alkanoic acids having the general formula C1(CF2CFC1)XCF2C02H is described. These acids, which contain an even number of carbon atoms, are prepared by the hydrolysis of the corresponding alkanes, C1(CF2CFC1)X+ jCl.Nomenclature. The International system of nomenclature is cumbersome to use for describing chlorofluorocarbons. Hence, in this article the compound is described by the number of carbon atoms present and the nature of the functional group.Thus, 3,4-dichloropentafluorobutyric acid, C1CF2CFC1CF2C02H, is designated as the C4 chlorofluorocarboxylic acid.These acids are commercially available under the trade name of KEL-F acids (registered trade-mark of the M. W. Kellogg Co. for its fluorocarbon polymers).PHYSICAL PROPERTIES AND ANALYTICAL DATA Solubility and Surface Activity. The chlorofluorocarboxylic acids are soluble in most organic liquids: aromatics, aliphatics, ethers, ketones, esters, and chlorinated hydrocarbons.The solubility of the chlorofluorocarboxylic acids in water depends markedly on the chain length.The C4 chlorofluorocarboxylic acid is completely miscible with water, whereas the C, and higher acids have very limited solubility. Determination of the exact solubility limits of these acids in water is complicated by the fact that they probably exist as ions only in very dilute solution. As the acid concentration is increased, small spherical micelles are formed, which undergo further development into laminar micelles in which the degree of order is very great. This behavior has been extensively investigated for thehydroperfluoro acids by Arrington and Patterson (l). The concentration at which critical micelle formation occurs corresponds approximately to the break in the surface tension vs. concentration curve.This break occurs, as can be seen in Figure 1, at 15 grams per 100 ml. for the C4 chlorofluorocarboxylic acid, at 0.5 gram per 100 ml.for the C9 compound, and at 0.002 gram per 100 ml. for the C12 compound. All surface tensions were determined on a precision model DuNouy tensiometer.The surface activity of the chlorofluorocarboxylic acids develops even with very short chain lengths-that is, C6 or C8-whereas the hydrocarbon analogs do not develop

Degradation Pathways and Complete Defluorination of Chlorinated Polyfluoroalkyl Substances (Clx−PFAS)

“…Those structures have been well known as building blocks and degradation products of surfactants 13,14 and coatings. 15,16 However, "alternative" PFAS containing −O−, [17][18][19] -H, 20,21 and -Cl 22,23 in the fluorinated moiety (RF) have also been systematically developed and extensively applied for decades. Recent studies have confirmed their negative health effects [24][25][26][27] and worldwide pollution in water [28][29][30][31][32][33][34][35][36] and soil.…”