Deep eutectic solvents: Quantum chemical investigation, thermal stability and physicochemical properties

The current quantum-based research focuses on the eutectic mixtures formulated by combining hydrogen bond donors (Urea, Lactic acid, Xylitol, Proline Xylitol) and acceptor (Betaine, Choline chloride, Proline) molecules. The quantum chemical investigation reveals that DESs Choline chloride-Proline and Choline chloride-Xylitol are the best solvents with the lowest energy gap, highest chemical softness, and the least chemical hardness. FTIR spectroscopy spectra provided evidence of the production of new hydrogen bonds between the two DES components, illuminating the mechanisms behind the impact of the components on the physicochemical characteristics of the DESs. The thermal stability, viscosity, electrical conductivity of DESs under the effect of type of HBAs/HBDs was studied. The influence of the water on the electrical conductivity, density and viscosity are discussed. The initiation of decomposition temperatures for DESs was derived from dynamic thermogravimetric analysis (TGA). DESs have the second level of thermal stability, which means they can be used in technological processes with a range of operating temperatures within similar to 100-150 degrees C.