Volumetric properties of binary mixtures containing chiral ionic liquids with a (−)-menthol substituent with acetonitrile at 298.15 K

The intermolecular interactions and the influence of alkyl chain length have been investigated for three binary systems of 3-alkyl-1-[(1 R ,2 S ,5 R )-(−)-menthoxymethyl]imidazolium bis(trifluoromethylsulfonyl)imide ionic liquid (alkyl = butyl, octyl, and dodecyl) with acetonitrile at 298.15 K by means of density measurements over the entire composition range. From the experimental values, the excess molar volumes and partial molar volumes were calculated and subsequently fitted using the Redlich–Kister equation. We have found that the excess molar volumes were negative for all three systems corresponding to a better arrangement of the molecules and/or stronger interactions. The parameters of the Redlich–Kister equation were optimized by means of a robust regression along a gnostic influence function. This made possible a deeper analysis of the experimental data. Partial molar volumes and excess molar volumes at infinite dilution using these parameters could then be calculated, allowing for a sound estimate of the solute–solvent interaction between the studied ionic liquids and acetonitrile. Graphical abstract