Ion - reagent interactions contributing to ionic liquid solvent effects on a condensation reaction

Keaveney, Sinead Teresa; Harper, Jason Brian; Croft, Anna K.

Abstract

Molecular dynamics simulations of solutions of hexan-1-amine or 4-methoxybenzaldehyde in acetonitrile, an ionic liquid/ acetonitrile mixture (XIL = 0.2), and a number of different (neat) ionic liquids were performed, to further understand the solvent effects on the condensation reaction of these species. This work indicates that, in the presence of an ionic liquid, the amine group of hexan-1-amine is exclusively solvated by the compo- nents of the ionic liquid, and not by acetonitrile, and that the anion interacts with the aldehyde group of 4-methoxybenzalde- hyde. These interactions showed little dependence on the proportion of the ionic liquid present. When varying the cation of the ionic liquid there were changes in the cation–amine interaction, and 1-butyl-2,3-dimethylimidazolium bis (trifluoro-methanesulfonyl) imide ([Bm2im][N(CF3SO2)2]) was found to order more than expected about the amine. This ordering is likely the origin of the large rate constant values determined in [Bm2im][N(CF3SO2)2] for this condensation reaction and explains an anomaly seen previously. When changing the anion, changes were seen in the interactions between both the cation and anion with hexan-1-amine, and the anion with 4-methoxyben- zaldehyde. The differing magnitude of these interactions likely causes subtle changes in the activation parameters for this condensation reaction, and provides an explanation for the anomalous rate constant values previously determined when varying the anion.

Citation

Keaveney, S. T., Harper, J. B., & Croft, A. K. (2018). Ion - reagent interactions contributing to ionic liquid solvent effects on a condensation reaction. ChemPhysChem, 19(23), 3279-3287. https://doi.org/10.1002/cphc.201800695

• Journal Article Type: Article
• Acceptance Date: Oct 5, 2018
• Online Publication Date: Oct 5, 2018
• Publication Date: Oct 5, 2018
• Deposit Date: Oct 29, 2018
• Publicly Available Date: Oct 6, 2019
• Journal: ChemPhysChem
• Print ISSN: 1439-4235
• Electronic ISSN: 1439-7641
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 19
• Issue: 23
• Pages: 3279-3287
• DOI: https://doi.org/10.1002/cphc.201800695
• Keywords: Ionic liquid; Molecular dynamics; Solvent effect; Interactions; Ordering
• Public URL: https://nottingham-repository.worktribe.com/output/1205461
• Publisher URL: https://onlinelibrary.wiley.com/doi/abs/10.1002/cphc.201800695
• Additional Information: This is the peer reviewed version of the following article: Keaveney, S.., Harper, J. and Croft, A.. (2018), Ion ‐ reagent interactions contributing to ionic liquid solvent effects on a condensation reaction. ChemPhysChem., which has been published in final form at https://doi.org/10.1002/cphc.201800695. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.