Enthalpies of transfer of tetrabutylammonium bromide as indicators of the structure of aqueous solvents: aqueous methanol, ethanol, propan-1-ol, 2-methylpropan-2-ol and 1,4-dioxane systems

Abstract

Enthalpies of transfer for tetrabutylammonium bromide from water to aqueous methanol, ethanol and 1,4-dioxane are reported and analysed in terms of solvation theory. Combination of these analyses with those for aqueous propan-1-ol and 2-methylpropan-2-ol (TBA) mixtures shows that the extent to which tetrabutylammonium bromide disrupts the solvent structure increases systematically from aqueous methanol to aqueous TBA, with those for aqueous methanol and 1,4-dioxane being comparable. The concentration of the organic cosolvent at which the water structure breaks down decreases in a similar order. These changes in the solvation of tetrabutylammonium bromide are discussed in terms of the effects of the organic cosolvents on the aqueous structure.