Density, viscosity, excess property and intermolecular interaction visualisation studies of trans-1,2-diaminocyclohexane plus water mixture

The determined density and viscosity data of trans-1,2-diaminocyclohexane (t-DCH) + water mixtures decrease with the increase in the temperature from 293.15 K to 333.15 K at atmospheric pressure, while all of the data show a maximum value along with the molar fraction of t-DCH increasing. In addition, excess molar volume (V-E), viscosity deviation (Delta eta) and excess Gibbs free energy (Delta G*(E)) were calculated and correlated using the Redlich-Kister equation. All of the V-E values are negative, while Delta eta and Delta G*(E) are positive. The intermolecular interactions between t-DCH and water were characterised by quantum chemistry methods. The length of hydrogen bonds, binding energy, and the topological properties of electron density at bond critical points are calculated. The results show that the stability of the t-DHH trimer is stronger than that of the t-DH dimer. On the basis of theoretical calculation, the reason why the density and viscosity of t-DCH+water binary system increases first and then decreases is explained.