title: Aqueous phase hydration and hydrate acidity of perfluoroalkyl and n:2 fluorotelomer aldehydes.
abstract: The SPARC software program and comparative density functional theory (DFT) calculations were used to investigate the aqueous phase hydration equilibrium constants (Khyd) of perfluoroalkyl aldehydes (PFAlds) and n:2 fluorotelomer aldehydes (FTAlds). Both classes are degradation products of known industrial compounds and environmental contaminants such as fluorotelomer alcohols, iodides, acrylates, phosphate esters, and other derivatives, as well as hydrofluorocarbons and hydrochlorofluorocarbons. Prior studies have generally failed to consider the hydration, and subsequent potential hydrate acidity, of these compounds, resulting in incomplete and erroneous predictions as to their environmental behavior. In the current work, DFT calculations suggest that all PFAlds will be dominantly present as the hydrated form in aqueous solution. Both SPARC and DFT calculations suggest that FTAlds will not likely be substantially hydrated in aquatic systems or in vivo. PFAld hydrates are expected to have pKa values in the range of phenols (ca. 9 to 10), whereas n:2 FTAld hydrates are expected to have pKa values ca. 2 to 3 units higher (ca. 12 to 13). In order to avoid spurious modeling predictions and a fundamental misunderstanding of their fate, the molecular and/or dissociated hydrate forms of PFAlds and FTAlds need to be explicitly considered in environmental, toxicological, and waste treatment investigations. The results of the current study will facilitate a more complete examination of the environmental fate of PFAlds and FTAlds.
authors.affiliation: a Chemologica Research , Moose Jaw , Saskatchewan , Canada.
authors.forename: Sierra
authors.initials: S
authors.lastname: Rayne
authors.affiliation: b Department of Environmental Engineering Technology , Saskatchewan Polytechnic , Moose Jaw , Saskatchewan , Canada.
authors.forename: Kaya
authors.initials: K
authors.lastname: Forest
mesh_terms: D000179:Acrylates / Q000737:chemistry*; D000447:Aldehydes / Q000737:chemistry*; D005465:Fluorocarbon Polymers; D005466:Fluorocarbons / Q000737:chemistry*; D006801:Humans; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D000179:Acrylates; D000447:Aldehydes; D005465:Fluorocarbon Polymers; D005466:Fluorocarbons; D006845:Hydrocarbons, Fluorinated; D007220:Industrial Waste; D014874:Water Pollutants, Chemical; C540553:fluorotelomer acrylate polymers
keywords: Hydration; fluorotelomer aldehydes; hydrate acidity; perfluoroalkyl aldehydes