Effect of Modifying the Anion of an Ionic Liquid on the Outcome of an SN2 Process

Abstract

The effect of a series of ionic liquids containing different anions (bis(trifluoromethanesulfonyl)imide, dicyanimide, hexafluorophosphate, tetrafluoroborate, and bromide) on the rate constant of a bimolecular substitution process was investigated. A general ionic liquid effect was noted, with increases in the rate constant observed in all ionic liquids used when compared with that in acetonitrile. Temperature-dependent kinetic data allowed calculation of activation parameters in each of the reaction mixtures considered; these parameters showed that the microscopic origins of the rate enhancements observed were not the same for all of the ionic liquids used, demonstrating the importance of the nature of the anion.

Unimolecular Solvolyses in Ionic Liquid: Alcohol Dual Solvent Systems

“…In conclusion, the favorability of the substitution and the elimination mechanistic pathways correlate strongly, though not completely, with the Kamlet-Taft solvatochromic parameters of the hydrogen bond donating and accepting ability of the ILs. It is interesting to note that this differs from the results found for bimolecular (S N 2) substitution reactions [10,11].…”

“…Molecules 2016, 21, 60 2 of 8 IL anion [11] on SN2 reactivity. Their work has shown that the identities of both the IL cation and anion have little effect on the reaction outcome other than general electrostatic effects.…”

“…Comprehensive reviews have been published by Lancaster [8] and Hallett and Welton [9]. More recently, the Harper group has undertaken more detailed studies of the effects of individually varying the IL cation [10] and the IL anion [11] on S N 2 reactivity. Their work has shown that the identities of both the IL cation and anion have little effect on the reaction outcome other than general electrostatic effects.…”

Developing principles for predicting ionic liquid effects on reaction outcome. The importance of the anion in controlling microscopic interactions

“…6,7,[16][17][18][19][20][21][22][23][24] The use of this method allows convenient analysis of this reaction 27 and circumvents any issues with work-up of the reaction mixture (such as selective extraction of components of the reaction mixture 16 ). 6,7,[16][17][18][19][20][21][22][23][24] The use of this method allows convenient analysis of this reaction 27 and circumvents any issues with work-up of the reaction mixture (such as selective extraction of components of the reaction mixture 16 ).…”

Fluorine Chemistry

“…Blanch and Wentrup (University of Queensland) describe an investigation into fluorinated carbene reactive intermediates [1] ; Read and co-workers (UNSW) report on the synthesis of novel fluorous surfactant molecules [2] ; Chebib (University of Sydney) and co-workers describe the receptor binding properties of shape-controlled fluorinated GABA analogues [3] ; Matesic and co-workers (Australian Nuclear Science and Technology Organisation) publish a microfluidic protocol for the automated production of 18 F-labelled compounds [4] ; Fraser and Easton (ANU) review the state-of-the-art in biosynthesis approaches to fluorinated peptides and proteins [5] ; Gardiner (CSIRO) reviews the production and commercial applications of fluoropolymers [6] ; Patel and Liu (Macquarie University) describe the synthesis and conformational analysis of fluorinated N-heterocycles [7] ; Harper and co-workers (UNSW) report on the outcomes of S N 2 reactions performed in fluorinated ionic liquid media [8] ; Kassiou and co-workers (University of Sydney) report on the clandestine production of fluorinated recreational drugs [9] ; Hunter and co-workers (UNSW) describe an investigation of fluorinated proline derivatives as enantioselective organocatalysts [10] ; and in an international contribution to this issue, O'Hagan and co-workers (University of St Andrews, UK) report on the fluorovinyl thioether functional group as a novel potential bioisostere of thioester enolates. [11] I sincerely thank all of the authors who have made such fine contributions to this Research Front, as well as the editorial and administrative staff of Aust.…”