Densities, Speeds of Sound and Heat Capacities of Binary and Ternary Mixtures Containing Cyclic Amines, Lactam and Pyridine

The densities, ρ, speeds of sound, u, of binary piperidine or 1-methylpiperidine (1) + 2-pyrrolidinone or pyridine (2), and densities, ρ123, speeds of sound, u123, of ternary piperidine or 1-methylpiperidine (1) + 2-pyrrolidinone (2) + pyridine (3) mixtures and molar heat capacities, CP, for the aforesaid binary mixtures have been measured over the entire composition range at temperatures ranging from (293.15–308.15) K with an increment of 5 K. The excess molar volumes $$V^{\text{E}}$$ , $$V_{123}^{\text{E}}$$ , excess isentropic compressibilities, $$\kappa_{S}^{\text{E}}$$ , $$(\kappa_{S}^{\text{E}} )_{123}$$ for the binary and ternary mixtures and excess heat capacities, $$C_{P}^{\text{E}}$$ , for investigated binary mixtures (determined by using experimental data) were fitted with the Redlich–Kister equations, and adjustable binary as well as ternary parameters along with the standard deviations have been estimated. The analyses of $$V^{\text{E}}$$ , $$\kappa_{S}^{\text{E}}$$ , $$C_{P}^{\text{E}}$$ data, quantum mechanical calculations and IR spectra of binary mixtures have revealed that piperidine (1) + 2-pyrrolidinone (2) mixtures are characterized by interactions between nitrogen and hydrogen atoms of piperidine with the hydrogen and oxygen atoms of 2-pyrrolidinone; 1-methylpiperidine (1) + 2-pyrrolidinone (2) mixtures are characterized by interactions between nitrogen and electron deficient carbon atom of 1-methylpiperidine with hydrogen and oxygen atoms of 2-pyrrolidinone; piperidine (1) + pyridine (2) mixtures are characterized by interactions between the hydrogen atom of piperidine with the nitrogen atom of pyridine; 1-methylpiperdine (1) + pyridine (2) mixtures are characterized by the interaction of the nitrogen atom of 1-methylpiperidine with the Π-electron cloud of pyridine’s aromatic ring.