Solute–solvent interactions in lactams–water ternary solvents

Abstract

This work reports on a variety of experiments performed as a contribution to an improved understanding of the structure and dynamics of amide-water mixtures. Several thermophysical properties of the pyrrolidin-2-one–N-methylpyrrolidinone–water ternary mixed solvent and its binary constituents were measured at 298.15 K. From the experimental readings excess and mixing properties were evaluated and analyzed in connection with structural effects and ternary interactions. The properties investigated support the formation of strong hydrogen bonds between water and the cyclic amides. For the binary constituents, the derived properties support 1∶2 PYR–water and 1∶3 NMP–water intermolecular interactions. The observed weakening of hydrogen bonds in the ternary system compared with the binary constituents reveals that no significant ternary net interactions are present in the mixture.