Siberian Federal University

The paper presents the results of a comparative study of two different methods for preparing three- component systems of deep eutectic solvents (DESs) based on tetra atomic alcohol, urea and a salt of a quaternary ammonium base. To study the phase equilibrium of mixtures of hydrogen bond donors and acceptors, two- component mixtures of different molar ratios of components, from 1:10 to 10:1 mole fractions, were prepared, followed by determination of the melting/crystallization temperature and construction of phase equilibrium diagrams of the components. Based on the results of a study of phase equilibrium diagrams of two component systems and the established coordinates of eutectic points, a phase equilibrium diagram of a three- component system was constructed. A study of two methods for preparing a three- component DES mixture (preparation of binary systems with the addition of a third component and a method of simultaneous mixing of three components) showed that the most correct is the simultaneous mixing of all three components, based on a theoretical calculation of the composition of a three- component mixture from two- component mixtures of eutectic composition