Pure and Applied Chemistry

Abstract: The goal of this work is to consider some peculiarities of heterogeneous systems with chemical interactions. The main task is to analyze the features of liquid–liquid (LL) phase diagrams of the systems with equilibrium and nonequilibrium chemical reaction in solution. The consideration of topology of these phase diagrams should include additional elements, such as stoichiometric lines, chemical equilibrium (CE), and isoaffinity manifolds (i.e., curves, surfaces, or hypersurfaces of constant affinity). The thermodynamic conditions of mutual disposition of LL tie-lines, isoaffinity, and stoichiometric lines in ternary system are presented in the paper. Quaternary mixtures are discussed with the use of our experimental data on the solubility in the systems with ethyl acetate and n-propyl acetate synthesis reactions. The binodal and CE surfaces in these systems are presented. The opportunity of simultaneous LL and CE is discussed. The special aim is to consider the critical surfaces in these systems: the examples are presented on the basis of our experimental data.