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

Sinead T. Keaveney*, Jason B. Harper, Anna K. Croft

*Corresponding author for this work

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Molecular dynamics simulations of solutions of hexan-1-amine or 4-methoxybenzaldehyde in acetonitrile, an ionic liquid/acetonitrile mixture (χIL=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 components of the ionic liquid, and not by acetonitrile, and that the anion interacts with the aldehyde group of 4-methoxybenzaldehyde. 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(trifluoromethanesulfonyl)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-methoxybenzaldehyde. 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.

Original languageEnglish
Pages (from-to)3279-3287
Number of pages9
JournalChemPhysChem
Volume19
Issue number23
Early online date5 Oct 2018
DOIs
Publication statusPublished - 5 Dec 2018

Keywords

  • interactions
  • ionic liquids
  • molecular dynamics
  • ordering
  • solvent effects

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