INTERACTIONS IN SOLUTIONS - A CALORIMETRIC STUDY OF PURE AND MIXED-SOLVENT SYSTEMS

Enthalpies of solution of electrolytes as well as nonelectrolytes in several pure and mixed solvents are discussed. The resulting enthalpies of transfer from one solvent to another in solvent systems containing water show the influence of hydrophobic hydration for solutes containing alkyl groups, viz. tetraalkylammonium bromides, alkanols and substituted ureas. Enthalpies of dilution give information on the energetic aspects of solute-solute interactions. Here too, the mediating solvent is important and when hydrophobic solutes are involved water distinguishes itself from other solvents. Attention is given to a group of dipeptide amides as model compounds for intramolecular interactions of globular proteins. In amidic solvents with functional groups similar to those of the dipeptides, the influence of size and shape of the alkyl groups and that of chirality is discussed.