Early Events in the Reductive Dehalogenation of Linear Perfluoroalkyl Substances

This work details the early events in the reductive defluorination of perfluoroalkyl substances (PFASs) and presents a straightforward methodology for predicting the reduction behavior of the perfluoroalkyl acids (PFAAs) using electronic structure calculations. Electron attachment to linear perfluorocarboxylic acids generally occurs at the alpha-carbon and is energetically not correlated to chain length, contrary to the case for linear perfluoroalkanesulfonates, where electrons generally insert into other positions. Perfluorooctanesulfonate and perfluorooctanoic acid, two widely studied and scrutinized PFAAs, are therefore predicted to be reduced through diverging pathways. Our protocol can predict the standard reduction potentials of PFAAs, provides a rational basis for probing reaction intermediates, establishes free energy relationships, and accounts for PFASs' inherent structural diversity beyond the linear substrates.