Enthalpies of transfer of tetrabutylammonium bromide from water to highly aqueous water–methanol, –ethanol, –propan-1-ol and –acetonitrile mixtures at 298 K: consideration of the extended coordination model solvation parameters

Abstract

Previous studies have established that the extended coordination model of solvation can satisfactorily account for the variation in the transfer enthalpies of solutes in mixed-solvent systems. However, the model parameter relating to the solute-induced disruption of the solvent structure shows a marked dependence on the nature of the mixed solvent. This result is not consistent with the underlying model of the solvation process.

In the present paper we report the transfer enthalpies of tetrabutylammonium bromide, for which this dependence is large, into a series of highly aqueous mixed solvents. Analysis of these in terms of the extended coordination model confirms both the model's ability to account for the experimental data, and the variability of the structural disruption parameter. The possible origins of this latter result are considered in detail.