Thermodynamics of mixtures with strongly negative deviations from Raoult's law. XII. Densities, viscosities and refractive indices at T = (293.15 to 303.15) K for (1-heptanol, or 1-decanol + cyclohexylamine) systems. Application of the ERAS model to (1-alkanol + cyclohexylamine) mixtures

Highlights: • The properties (ρ,η,n_D) at T = (293.15 to 303.15) K are given for CH₃(CH₂)_nOH (n = 6,9) + C₆H₁₁NH₂. • These data are used to determine V_m^E, Δη, ΔG^∗,Δn_D, and R_m. • (1-Alkanol + cyclohexylamine) mixtures have been studied using the ERAS model. V_m^E and R_m increase with the increasing of n, while Δη and Δn_D decrease. • (Alkanol + amine) interactions become weaker and dispersive ones are more important when n increases. - Abstract: Densities, ρ, kinetic viscosities, ν, and refractive indices, n_D, have been measured for (1-heptanol or 1-decanol + cyclohexylamine) systems at T = (293.15 to 303.15) K. The experimental ρ, ν, n_D values were obtained using an Anton Paar DMA 602 vibrating-tube densimeter, an Ubbelohde viscosimeter and a refractometer model RMF970, respectively. These data are used to determine a number of derived properties: excess molar volumes, V_m^E, dynamic viscosities, η, deviations of this magnitude from linear dependence on mole fraction, Δη, Gibbs energies of activation of viscous flow, ΔG^∗, deviations of n_D from the ideal state, Δn_D, or molar refractions, R_m. In addition, (1-alkanol + cyclohexylamine) mixtures have been studied by means of the ERAS model. The corresponding parameters are reported. Viscosity data have been correlated by the following semi-empirical equations: Grunberg–Nissan, Hind, Frenkel, Katti–Chaudhri, Tamura–Kurata, Teja–Rice, McAllister and Heric. The deviations obtained are usually lower than 2%. The large negative V_m^E values of the studied solutions reveal the existence of strong alcohol-amine interactions. The properties V_m^E and R_m increase with the increasing of the chain length of the 1-alcohol, while Δη and Δn_D decrease. These variations suggest that interactions between unlike molecules are weakened and dispersive interactions become more important when the alcohol size increases. On the other hand, ΔG^∗ is essentially determined by enthalpic effects. The effect of replacing cyclohexylamine by an isomeric amine, hexylamine (HxA), dipropylamine (DPA) or N,N,N-triethylamine (TEA) in mixtures with a given 1-alkanol is also investigated. It is shown that the strength of the methanol-amine interactions become stronger in the sequence: TEA < DPA < HxA ≈ cyclohexylamine. The application of the ERAS model to (1-alcohol + cyclohexylamine) mixtures supports these findings. The parameters obtained in this work fit well into the general ERAS treatment of (1-alkanol + amine) systems