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A Theoretical Study of Ene Reactions in Solution: A Solution‐Phase Translational Entropy Model
Author(s) -
Zhao Liu,
Li ShiJun,
Fang DeCai
Publication year - 2015
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201500662
Subject(s) - chemistry , ene reaction , gibbs free energy , thermodynamics , enthalpy , solvent , entropy (arrow of time) , standard molar entropy , solvent effects , density functional theory , activation energy , computational chemistry , standard enthalpy of formation , organic chemistry , physics
Several density functional theory (DFT) methods, such as CAM‐B3LYP, M06, ωB97x, and ωB97xD, are used to characterize a range of ene reactions. The Gibbs free energy, activation enthalpy, and entropy are calculated with both the gas‐ and solution‐phase translational entropy; the results obtained from the solution‐phase translational entropies are quite close to the experimental measurements, whereas the gas‐phase translational entropies do not perform well. For ene reactions between the enophile propanedioic acid (2‐oxo‐1,3‐dimethyl ester) and π donors, the two‐solvent‐involved explicit+implicit model can be employed to obtain accurate activation entropies and free‐energy barriers, because the interaction between the carbonyl oxygen atom and the solvent in the transition state is strengthened with the formation of C−C and O−H bonds. In contrast, an implicit solvent model is adequate to calculate activation entropies and free‐energy barriers for the corresponding reactions of the enophile 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione.