Abstract
AbstractTemperature dependent rate constants were estimated for the acid- and base-catalyzed and neutral hydrolysis reactions of perfluorinated telomer acrylates (FTAcrs) and phosphate esters (FTPEs), and the SN1 and SN2 hydrolysis reactions of fluorotelomer iodides (FTIs). Under some environmental conditions, hydrolysis of monomeric FTAcrs could be rapid (half-lives of several years in marine systems and as low as several days in some landfills) and represent a dominant portion of their overall degradation. Abiotic hydrolysis of monomeric FTAcrs may be a significant contributor to current environmental loadings of fluorotelomer alcohols (FTOHs) and perfluoroalkyl carboxylic acids (PFCAs). Polymeric FTAcrs are expected to be hydrolyzed more slowly, with estimated half-lives in soil and natural waters ranging between several centuries to several millenia absent additional surface area limitations on reactivity. Poor agreement was found between the limited experimental data on FTPE hydrolysis and computational estimates, requiring more detailed experimental data before any further modeling can occur on these compounds or their perfluoroalkyl sulfonamidoethanol phosphate ester (PFSamPE) analogs. FTIs are expected to have hydrolytic half-lives of about 130 days in most natural waters, suggesting they may be contributing to substantial FTOH and PFCA inputs in aquatic systems. Perfluoroalkyl sulfonamides (PFSams) appear unlikely to undergo abiotic hydrolysis at the S-N, C-S, or N-C linkages under environmentally relevant conditions, although potentially facile S-N hydrolysis via intramolecular catalysis by ethanol and acetic acid amide substituents warrants further investigation.
Highlights
The fate of perfluorinated compounds (PFCs) in natural and engineered systems is of current interest.[13]
No works have explored in detail the potential abiotic hydrolysis of any fluorotelomer alcohols (FTOHs), perfluoroalkyl carboxylic acids (PFCAs), or PFSA precursor compounds under the wide range of solution conditions that can be found in aquatic systems
To better understand the potential abiotic hydrolysis of PFCA and PFSA precursors in natural and engineering systems, the current study critically examines the limited direct information available on selected PFCs, integrates the broader relevant literature on similar compound classes, and uses various computational approaches to estimate the hydrolytic behavior of FTAcrs, FTPEs, perfluoroalkyl sulfonamidoethanol phosphate ester (PFSamPE), fluorotelomer iodides (FTIs), and perfluoroalkyl sulfonamides (PFSams)
Summary
The fate of perfluorinated compounds (PFCs) in natural and engineered systems is of current interest.[13]. Among the various possible precursors, the perfluorinated telomer acrylates (FTAcrs), phosphate esters (FTPEs), iodides (FTIs), PFSams, and perfluoroalkyl sulfonamidoethanol phosphate esters (PFSamPEs) (Fig. 1) have functional groups that may be susceptible to hydrolytic cleavage. In addition to their direct releases into the environment near production and processing facilities, these compounds may be released from consumer products, where they can be present at concentrations up to the low percent by weight.[24]. [43] Glowa, G.A.; Wren, J.C. Aqueous-gas phase partitioning and hydrolysis of organic iodides.
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