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ChemPhysChem [LCSOM]

juil. 6 2020

Abstract :

To figure out the possible role of 1,1,1,3,3,3‐hexafluoropropan‐2‐ol (HFIP) as well as to provide reference thermochemical data in solution, the formation of Lewis acid‐base complexes between HFIP (Lewis acid) and a series of 8 different Lewis bases (3 sulfoxides, 3 Nsp2 pyridine derivatives, 1 aromatic amine, 1 cyclic aliphatic ether) was examined by Isothermal Titration Calorimetry (ITC) experiments and static Density Functional Theory augmented with Dispersion (DFT‐D) calculations. Measured ITC association enthalpy values ΔHa spanned ‐9.3 kcal/mol to ‐14 kcal/mol. Computations including a PCM implicit solvation model produced similar exothermicity of association of all studied systems compared to the ITC data with ΔHa values ranging ‐8.5 – ‐12.7 kcal/mol. An additional set of calculations combining implicit and explicit solvation by chlorobenzene of the reactants, pointed out the relatively low interference of the solvent with the HFIP‐base complexation, which main effect is to slightly enhance the Gibbs energy of the HFIP‐Lewis base association. It is speculated that the interactions of bulk HFIP with Lewis bases therefore may significantly intervene in catalytic processes not only via the dynamic miscrostructuration of the medium but also more explicitly by affecting bonds’ polarization at the Lewis bases.

Reference :

Jean-Pierre Djukic, Milan R. Milovanović, Quentin Dherbassy, Joanna Wencel-Delord, Françoise Colobert, Snežana D. Zarić

The affinity of some Lewis bases for Hexafluoroisopropanol as a reference Lewis acid: an ITC/DFT study.

ChemPhysChem, First published: 03 July 2020 – DOI : https://doi.org/10.1002/cphc.202000560


Contact chercheur :

Jean-Pierre Djukic, équipe LCSOM, Institut de Chimie (UMR 7177).