New physicochemical data for trans-perfluorodecalin (trans-PDF) and cis-perfluorodecalin (cis-PFD) are presented. Based on the differential scanning calorimetry, the temperature and heat of the solid−liquid phase transition are determined. The coefficients of Antoine’s equation are calculated based on the experimental temperature–pressure dependence data. This article also presents data on the rheological properties («zero» shear viscosity and apparent activation energy for the viscous flow) of the studied compounds. The dependencies of refractive index and excess volume (density) on temperature are studied. Gas chromatography–mass spectrometry data and FTIR, ¹³C NMR, and ¹⁹F NMR spectra are provided. The dependencies are given for the perfluoro(butylcyclohexane) (BCH)–trans-PFD, BCH–cis-PFD, and trans-PFD–cis-PFD binary systems and BCH–trans-PFD–cis-PFD ternary system: refractive index and density (liquid molar volume and excess molar volume) of composition and temperature. The dependences of the excess molar volume on the composition and temperature of the mixtures are correlated with Redlich-Kister and Kohler equations.

The purification of perfluoro(7-methylbicyclo[4.3.0]nonane) industrial fractions with a component content above 0.950 in mass fraction is not effective and requires the use of special separation methods. According to experimental data, the separation factor of the initial mixture during distillation with no additional substances is close to 1. At the same time, the addition of acetone (Ac) makes it possible to significantly intensify the process. Ac allowed for obtaining MBCN with a purity higher than 0.998 in mass fraction in one separation cycle, and the degree of recovery was more than 0.85 by weight. The paper presents data on the distribution of components (target product, identified and unidentified impurities of electrochemical fluorination of decalin) between the distillate and bottom product fractions, separation factor, liquid–liquid phase equilibrium in the MBCN-Ac system, and characteristics of the MBCN-Ac heteroazeotrope.

The process of crystallization separation of an industrial mixture of perfluorinated cycloalkanes was considered. The content of target products, cis- and trans-isomers of perfluorodecalin (PFD), in all initial fractions of the investigated samples of the reaction mixture was at least 70 wt.%. Based on the experimental data, the dependences of the crystallization (partition) coefficients between the solid and mother liquor ($D^{s/l}$), the enrichment factor (η^s), and the separation factor (F^s) on the ratio of trans-PFD to cis-PFD, the ratio of mother liquor to solid, and crystallization temperature in the range −50–15 °C were obtained. It was shown that the values $D^{s/l}$ and η^s depended significantly on the concentration of trans-PFD in the initial solution, and that the value of F^s decreased as the process temperature rose.