Viscosities and densities for binary mixtures of N-methylpiperazine with methanol, ethanol, n-propanol, iso-propanol, n-butanol and iso-butanol at 293.15, 298.15 and 303.15 K

Abstract

Viscosity ( η) and density ( ρ) values are reported for binary mixtures of N-methylpiperazine (NMP) with methanol, ethanol, n-propanol, iso-propanol, n-butanol and iso-butanol over the entire range of mole fraction at 293.15, 298.15, and 303.15 K and atmospheric pressure. The viscosity deviation (Δ η), excess molar volume ( V E), and excess Gibbs energy of activation ( G *E) have been calculated. These results were fitted with Redlich–Kister type polynomial equation. All the investigated systems exhibit very large positive values of Δ η and G *E, and negative values of V E over the whole composition range. The obvious deviations attribute to the strong cross association between the alkanol and NMP molecules through the hydrogen bond of O H ⋯ N. The temperature has significant effect on Δ η and relatively slight effect on V E and G *E. From the experimental data, the thermodynamic functions of activation have been estimated for each binary mixture. The viscosity data have been correlated with several semi-empirical equations. Two-parameter equation of McAllister can give satisfactory results.