Abstract
Thermodynamic activation parameters, enthalpies (Delta H-double dagger), entropies (Delta S-double dagger) and Gibbs energies (Delta G(double dagger)) for viscous flow of the systems tert-butanol (TB)+n-butylamine (NBA), TB+di-n-butylamine (DBA) and TB+tri-n-butylamine (TBA) have been calculated from measured density and viscosity data at temperatures ranging from 303.15 to 323.15 K over the composition range 0 <= x(2) <= 1, where x2 is the mole fraction of TB. For all systems, the corresponding excess properties Delta H-double dagger E, Delta S-double dagger E and Delta G(double dagger E) have been determined, which are negative in the whole range of composition. The observed negative excess activation properties have been accounted for in terms of dispersive forces and H-bonding. The derived properties are well represented by fourth degree polynomial equations whereas the excess properties could be fitted to third degree Redlich-Kister polynomial equations. Furthermore, the viscosities have been predicted by using the UNIFAC-VISCO model, Grunberg-Nissan model and McAllister three-body interaction model. The UNIFAC-VISCO model and Grunberg-Nissan model do not show good agreement with the experimental data, whereas the McAllister three-body interaction model shows excellent agreement for all three systems, with small average absolute percent deviations (AAD% = 0.6-2.3). The DFT-B3LYP method with the 6-311 G (d, p) basis set has been employed for the optimization of the geometry and calculation of the total energies of the pure compounds and their binary complexes.