The effects of a series of ionic liquids, with systematic variations in the cation, on the condensation of an alkyl amine with an aromatic aldehyde were investigated, and the outcomes compared with those predicted based on related reactions. The addition of ionic liquids increased the observed rate constant; the mole fraction dependence of this increase was qualitatively consistent with predictions. Temperature-dependent kinetic analyses were used to demonstrate that the microscopic origins of the effects were as forecast, though the relative weighting of enthalpic and entropic contributions was dependent on the salt used.

The self-diffusion coefficients of each component in mixtures of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Bmim][N(SO CF ) ]) and acetonitrile were determined. The results suggest that the hydrodynamic boundary conditions change from "stick" to "slip" as the solvent composition transitions from "ionic liquid dissolved in acetonitrile" (χ <0.4) to "acetonitrile dissolved in ionic liquid" (χ >0.4). At higher χ , the acetonitrile species are affected by "cage" and "jump" events, as the acetonitrile molecules reside nearer to the charged centre on the ions than in the "non-polar" regions. The self-diffusion coefficients of hexan-1-amine, dipropylamine, 1-hexanol and dipropylether in mixtures of [Bmim][N(SO CF ) ] and acetonitrile were determined. In general, the nitrogen-containing solutes were found to diffuse slower than the oxygen-containing solutes; this indicates that there are greater ionic liquid-N interactions than ionic liquid-O interactions. This work demonstrates that the self-diffusion coefficients of species can provide valuable information about solvent-solvent and solvent-solute interactions in mixtures containing an ionic liquid.

A series of nitrogen and phosphorus nucleophiles have been investigated to determine whether the previously established ionic liquid solvent effects on a bimolecular nucleophilic substitution (S N 2) reaction vary with the nature of the nucleophilic centre. Reaction of group 15 triphenyl nucleophiles with benzyl bromide showed a different trend in the rate constant with increasing proportions of ionic liquid in the reaction mixture than was observed with pyridine. This result suggests additional interactions are important; a supposition supported by differences in reaction outcome observed when the electrophile was varied in reactions with triphenylphosphine. A novel ionic liquid solvent effect was observed in the reaction of tributylamine with benzyl bromide, with the position of equilibrium varying with the proportions of the ionic liquid present in the reaction mixture. Overall, the work presented demonstrates the importance of considering all possible interactions between an ionic liquid solvent and species along the reaction coordinate and has expanded upon our current predictive framework for ionic liquid solvent effects. Such understanding is important as it allows further development of a predictive framework for the application of ionic liquids in preparative chemistry. ; Fax: +61 2 9385 6141; Tel: +61 2 9385 4692 † Electronic supplementary information (ESI) available: Preparation of the ionic liquid 6; details of the NMR signals used to follow reaction progress in each case; the mathematical forms from which the rate data was derived for each system; mole fraction kinetic dependence plot for the reaction between species 1 and 3; Eyring plots from which activation parameters were derived; the ratio between the forward and reverse rate constants for the reaction between reagents 3 and 10a; the compositions of all the stock solutions prepared; rate constant data, including the data on which Fig. S1 and S2-S6 are based, including temperature dependent kinetic data from which the activation parameters shown in Tables 1 and 5 are derived. See

Machine learning models were developed for an organic reaction in ionic liquids and validated on a selection of ionic liquids.

Rate constants for a bimolecular nucleophilic substitution (SN2) process in a range of ionic liquids are correlated with calculated parameters associated with the charge localisation on the cation of the...