Pyrrolidone Derivatives in Water Solution: An Experimental and Theoretical Perspective

In this paper thermophysical properties of 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-cyclohexyl-2-pyrrolidone, in binary and ternary liquid mixtures with water are reported at 298.15 K and 0.1 MPa over the whole composition range. Derived excess and mixing properties were used to analyze mixtures' structure. To infer a detailed picture of the intermolecular interactions in the studied fluids, attenuated total reflection infrared absorption spectroscopy was used. To study fluid properties from a molecular viewpoint, density functional theory computations were carried out, leading to structural and energetic information. Formation of H-bonding and dipolar interactions between cyclic amides and with water were observed, resulting in complex fluid structures that were stronger in binary mixtures containing water than in ternary ones. Intermolecular forces are weakened upon mixing by the presence of a second cyclic amide in the mixture.