Excess properties, computational chemistry and spectroscopic analyses of 1,2-propanediamine plus n-propanol/isopropanol binary mixtures

To understand excess properties and intermolecular interactions of 1,2-propanediamine and n-propanol/isopropanol binary mixtures, their density and viscosity were systemically measured at T = (298.15-318.15) K under atmospheric pressure (1005 hectopascals in Tianjin, China), and their excess molar volume (V-m(E)), viscosity deviation (Delta eta) and excess viscous activation free energy (Delta G(*E)) were also calculated. From the results of VmE, it can be inferred that two n-propanol/isopropanol molecules and one 1,2-propanediamine molecule have the strongest binding capacity and form the most stable intermolecular hydrogen bonds. The experimental density and kinematic viscosity were correlated and predicted by several semi-empirical models, among which the Jouyban-Acree model had a better fit for the density and the McAllister four-body equation had a better fit for the kinematic viscosity, and the calculated results of V-m(E), Delta eta and Delta G(*E) were analyzed using the R-K equation. Meanwhile, the apparent molar volume, partial molar volume, thermal expansion coefficient and viscous activation parameters of 1,2-propanediamine and n-propanol/isopropanol solutions were calculated and analyzed. After that, the existence of intermolecular hydrogen bonds (IHBs) between 1,2-propanediamine and n-propanol/isopropanol binary mixtures was demonstrated on the basis of computational chemistry. And then, the IHBs between 1,2-propanediamine and n-propanol/isopropanol binary mixtures with the form of -OH center dot center dot center dot NH2- were further confirmed based on Raman, ultraviolet (UV), fluorescence (FLS) and nuclear magnetic resonance (H-1 NMR) spectral technologies.

Automated summary

The excess properties and intermolecular interactions of 1,2-propanediamine and n-propanol/isopropanol binary mixtures were studied by measuring their density and viscosity and calculating the excess molar volume, viscosity deviation, and excess viscous activation free energy. The results indicated that the strongest binding capacity and most stable intermolecular hydrogen bonds were formed by two n-propanol/isopropanol molecules and one 1,2-propanediamine molecule. Various semi-empirical models were used to correlate and predict the experimental density and kinematic viscosity, and the calculated results were analyzed using the R-K equation. The existence of intermolecular hydrogen bonds between 1,2-propanediamine and n-propanol/isopropanol binary mixtures was demonstrated using computational chemistry and confirmed using spectroscopic technologies.