Physicochemical Properties of the Dicationic Ionic Liquid 1,2-Bis(1-methylimidazolium-3)ethane Dibromide

A dicationic ionic liquid of 1,2-bis(1-methylimidazolium-3)ethane dibromide of a new composition, having a solid state of aggregation, has been synthesized. The presence of the corresponding functional groups in the structure of the ionic liquid was confirmed by IR Fourier and NMR spectroscopy. It was established by viscosimetry that the viscosity of an aqueous solution of the dicationic ionic liquid increases with concentration due to association of the dicationic ionic liquid and water molecules. A conductometric study showed that the electrical conductivity increases with the concentration and temperature of the dicationic ionic liquid. The melting point of the obtained dicationic ionic liquid is 236 ± 0.5°C. The high melting point of the dicationic ionic liquid is explained by steric hindrances, caused by the fact that the imidazolium cations are linked to each other by an ethane chain, which promotes the convergence of ions and, as a result, does not prevent hydrogen bonding. At increased concentrations of the dicationic ionic liquid in aqueous solution, the surface tension of solutions decreases. The ion association is characterized by the negative Gibbs energy and enthalpy of aqueous solutions, which indicates that the interaction is spontaneous and exothermic.