Molecular Interactions in Binary Mixtures of Lactams with Cyclic Alkanones

Abstract

The densities ρ12, speeds of sound u12, for the binary mixtures of pyrrolidin-2-one or 1-methylpyrrolidin-2-one (NMP) (1) + cyclopentanone or cyclohexanone or cycloheptanone (2) at (293.15, 298.15, 303.15, 308.15 K), and excess molar enthalpies \( H_{12}^{\text{E}} \), of the same mixtures at 298.15 K have been measured as a function of composition. The observed data were employed to determine the excess molar volumes, \( V_{12}^{\text{E}} \), and excess isentropic compressibilities, \( \left( {\kappa_{S}^{\text{E}} } \right)_{12} \). The results have been analyzed in terms of the Graph and Prigogine–Flory–Patterson theories. The analysis of \( V_{12}^{\text{E}} \) data of pyrrolidin-2-one or NMP (1) + cyclic alkanones (2) mixtures in terms of Graph theory suggest that while pyrrolidin-2-one (1) + cyclic alkanones (2) are characterized by interactions between the hydrogen and oxygen atoms of pyrrolidin-2-one with the oxygen and carbon atoms of cyclic alkanones, 1-methyl pyrrolidin-2-one (1) + cyclic alkanones (2) mixtures are characterized by interactions between the nitrogen and oxygen atoms of NMP with the oxygen and carbon atoms of cyclic alkanones to form 1:1 molecular complexes. IR studies support this viewpoint. It has been observed that the \( V_{12}^{\text{E}} ,\,H_{12}^{\text{E}} \), and \( \left( {\kappa_{S}^{\text{E}} } \right)_{12} \) values evaluated by Graph theory compare well with their corresponding experimental values.