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Proton transfer between sulfonic acids and various propylamines by density functional theory calculations
Irina V Fedorova1, Lyubov P Safonova2
1G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, 1 Akademicheskaya Street, Ivanovo, 153045, Russia. fiv@isc-ras.ru.
Journal of Molecular Modeling
|July 5, 2023
Summary
Proton transfer in acid-base systems is complex. Computational studies reveal that while ionic pairs are favored by Coulomb interactions, molecular complexes can exhibit stronger hydrogen bonds, impacting acid-base interactions and protic ionic liquid design.
Area of Science:
- Computational Chemistry
- Physical Chemistry
- Materials Science
Background:
- Proton transfer in acid-base systems is not fully understood, with some reactions deviating from pKa predictions.
- Acid-base interactions are crucial in various chemical processes and material applications.
Purpose of the Study:
- To computationally investigate proton transfer from various acids to amines.
- To analyze the energetic and structural factors governing molecular complex and ionic pair formation.
- To establish relationships between interaction energies and proton affinity differences.
Main Methods:
- Density Functional Theory (DFT) calculations at the B3LYP-GD3/6-31++G(d,p) level.
- Analysis of potential energy curves along the proton transfer coordinate.
- Quantum Theory of Atoms in Molecules (QTAIM) and Natural Bond Orbital (NBO) analyses.
Main Results:
- Larger proton affinity differences (ΔPA) disfavor ionic pair formation.
- Hydrogen bonds in molecular complexes (e.g., PrA-MsO, PrA-BSu) can be stronger than in their ionic pairs.
- Coulomb interactions dominate ionic pair energies, followed by hydrogen bonding and dispersion forces.
Conclusions:
- Hydrogen bonding significantly contributes to acid-base interactions in molecular complexes.
- Ionic pair stability is influenced by cation structure and anion type, with implications for protic ionic liquid design.
- Findings expand the understanding of acid-base interactions and offer guidance for synthesizing novel protic ionic liquids.
Keywords:
DFT calculationsInteractionPropylaminesProton affinityProton transferStructureSulfonic acidsMore Related Videos
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