BEP-Like Correction of Nonequilibrium Thermodynamic Parameters of the Solvent-Assisted Reactions: The DFT and Ab Initio Study of Hydration, Peroxidation, and Enolization of Acetone and 1,1,1-Trifluoroacetone in Aqueous Solutions.

Abstract

The mechanisms of enolization and reactions of nucleophilic addition to carbonyl compounds were analyzed by density functional theory (DFT) (PBE1PBE) and ab initio (DLPNO-CCSD(T)) level of theory using the interaction of water and hydrogen peroxide with acetone and 1,1,1-trifluoroacetone (TFA) as the reference reactions. The transition states of the studied reactions were localized within the integrated approach that includes both the dielectric continuum theory (polarizable continuum model (PCM)) and the cyclic or two-cluster explicit solvation models. The considered models provide proton transfer in the enolization, hydration, and peroxidation reactions by the Grotthuss mechanism. It is shown that the calculated activation parameters at a sufficiently high level of theory and a sufficiently flexible solvation model can be additionally refined using the Bell-Evans-Polanyi (BEP)-like correction (in a form of the Bell-Evans-Polanyi equation), which is linear scaling of the model potential energy surface according to the equilibrium parameters of the reference reaction (experiment or high-level calculation). Quite good correspondence of the corrected and reference activation parameters and the lower sensitivity of the calculation results to the choice of the solvation model indicate the high reliability of the proposed BEP-like correction technique.