Thermodynamics of ketone plus amine mixtures 7. Volumetric and speed of sound data at (293.15, 298.15 and 303.15) K for 2-pentanone plus aniline, plus N-methylaniline, or plus pyridine systems

Densities, rho, and speeds of sound, u, of 2-pentanone + aniline, + N-methylaniline, or + pyridine systems have been measured at (293.15, 298.15 and 303.15) K and atmospheric pressure using a vibrating tube densimeter and sound analyzer Anton Paar model DSA-5000. The rho and u values were used to calculate excess molar volumes, V-m(E), and the excess functions at 298.15 K for the speed of sound, u(E), the thermal expansion coefficient, alpha(E)(P), and for the isentropic compressibility, kappa(E)(S) at 298.15 K. V-m(E) and kappa(E)(S) are both negative magnitudes and increase in the same sequence: aniline <N-methylaniline< pyridine, while uE is positive and increases in the opposite way. The similar trends are observed for mixtures including the same aromatic amines and propanone, 2-butanone or 2-heptanone. The data have been interpreted assuming strong ketone-amine interactions, which become weaker when the chain length of the 2-alkanone is increased in solutions with a given aromatic amine. Ketone-amine interactions are more easily created in mixtures with aniline. Interactions between unlike molecules are stronger than in 2-alkanone + dipropylamine, or + dibutylamine, or + triethylamine systems. These findings are confirmed by the results obtained from internal pressures and molecular interaction parameters for the investigated mixtures. (C) 2011 Elsevier B.V. All rights reserved.