Topological transformation of the phase diagram for the ternary system cesium nitrate-water-acetonitrile

In the ternary system cesium nitrate-water-acetonitrile, in which liquid-liquid phase separation with an upper critical solution point (UCSP) exists in the liquid binary subsystem, was studied in the range from ?5 to 120°C using visual polythermal analysis. Liquid-liquid phase separation in the ternary system is observed above 96.0°C and below 2.8°C. Acetonitrile distribution coefficients between the aqueous and organic phases of monotectic equilibrium were calculated for various temperatures. Phase isotherms of the system confirm the general scheme of the topological transformation of phase diagrams in salt-binary solvent ternary systems with salting out.