What Is So Special about the Sorption Behavior of Highly Fluorinated Compounds?

Abstract

Highly fluorinated organic compounds are often said to exhibit unique sorption and partition properties. Terms such as "fluorophilicity" have been used to describe these properties, and fudge factors depending on the degree of fluorination have been used in predictive partition models to make them work for fluorinated solutes. Here we demonstrate that highly fluorinated compounds differ from other molecules only in that they exhibit van der Waals interactions much smaller than those of other molecules of same size. A simple cavity model for partitioning is shown to give good results for fluorinated compounds if the nonspecific interactions are correctly parametrized.

Aqueous phase hydration and hydrate acidity of perfluoroalkyl and n:2 fluorotelomer aldehydes

“…Such potential errors with SPARC in dealing with the equilibrium behavior of perfluorinated compounds has been previously reported in the literature. [3,35,36].…”

Treatment technologies for aqueous perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA)

“…The diverse FC applications are due to the unique physiochemical properties [1][2][3] gained upon replacing the majority of the hydrogens in an organic with fluorines. Organic poly-and moreso perfluorination yields a more thermally stable (i.e., C 2 H 5 -H of 101 kcal/mol vs. C 2 F 5 -F of 127 kcal/mol, and CF 3 -CF 3 of 99 kcal/mol vs. CH 3 -CH 3 of 89 kcal/mol), a more oxidatively resistant (i.e., F + e -!…”

Congener specific organic carbon normalized soil and sediment-water partitioning coefficients for the C1 through C8 perfluoroalkyl carboxylic and sulfonic acids

“…This knowledge gap is of importance, since an inverse correlation was found between PFA chain length and the steady state biota sediment accumulation factors (BSAFs) using the aquatic oligochaete Lumbriculus variegatus, [78] highlighting the need to extend existing organic matter-water partitioning datasets for the longer chain PFAs to the shorter chain congeners who may have higher BSAFs. It should also be noted that the difficulty of both measuring and estimating the partitioning constants and physicochemical properties of perfluorinated compounds (PFCs) in general has led to a significant amount of discussion in the literature, [85][86][87][88][89][90][91][108][109][110][111][112][113] potentially dissuading rigorous investments in extended experimental investigations.…”