Effect of water as cosolvent in the organic phase on the partitioning of nonelectrolytes between aqueous solution and octan-1-ol

Enthalpies of solution at infinite dilution of propanone, tetrahydrofuran, n-propylamine, and tri-n-butylamine in water-octan-1-ol mixtures, Delta(soln)H degrees (oct-w), with water content ranging from zero to saturation have been determined, The observed trends of Delta(soln)H degrees (oct-w) vs. the mole fraction of water are discussed and compared with the trend of the apparent molar volume of water in octan-1-ol. The connection between structural organization of water in the solvent medium and enthalpies of solution are pointed out and discussed. An attempt is also made to evaluate the observed phenomenology in terms of a preferential solvation model.