High-Level Quantum Chemical Prediction of C–F Bond Dissociation Energies of Perfluoroalkyl Substances

Abstract

In this study, 550 C−F bond dissociation energies (BDEs) of a variety of per-and polyfluoroalkyl substances (PFASs) obtained from high-level DLPNO-CCSD(T)/CBS calculations were used to assess the accuracy of contemporary density functional theory (DFT) and semiempirical methods. DLPNO-CCSD(T)/CBS gas phase C−F BDEs fall between 404.9−550.7 kJ mol −1 and M06-2X and ωB97M-V in conjunction with the aug-cc-pVTZ basis set predicted BDEs closest to the benchmark level with a mean absolute deviation (MAD) of 7.3 and 8.3 kJ mol −1 , respectively. It was observed that DFT prediction errors increase with the degree of fluorination and system size. As such, previous model chemistry recommendations based on smaller nonfluorinated systems may not be carried over to modeling the energetics of PFASs and related systems.

Evolutionary obstacles and not C–F bond strength make PFAS persistent

“…The failure of many polyfluorinated compounds to undergo biodegradation in multiple environments is often attributed to the strength of carbon‐to‐fluorine (C–F) bonds (Berhanu et al., 2023 ; Key et al., 1997 ; Lorpaiboon & Ho, 2023 ; Xiao et al., 2023 ). The stability of PFAS to thermal, oxidative, and photochemical degradation is well known (Achiha et al., 2010 ; Haupt, 2021 ; Krespan, 1965 ; O'Hagan, 2008 ).…”

Uranium and lithium extraction from seawater: challenges and opportunities for a sustainable energy future

“…Recently, the use of density functional theory (DFT) computation has gained significant traction as a high-throughput tool to study materials properties such as atomic and electronic structures as well as stability and chemical reactivity from first principles. 256,257 This is joined by the growing interest in machine learning (ML), which – when combined with DFT computation – serves as a powerful predictive framework for materials discovery. A properly trained and optimized ML model by exploiting sizable DFT data from either empirical results or existing literature and databases can enable greater computational accuracy at a shorter lead time.…”

Accurate Enthalpies of Formation for PFAS from First-Principles: Combining Different Levels of Theory in a Generalized Thermochemical Hierarchy

“…In a separate study, Khan et al provided a systematic study for the decomposition of perfluorocarboxylic acids, up to and including PFOA . Lorpaiboon and Ho computed bond dissociation energies (BDE) for a broad range of PFAS containing up to 26 heavy atoms (e.g., PFPA), based upon DLPNO–CCSD­(T) single-point energies from DFT geometries . Raza et al.…”