Separation of an Industrial Mixture of Decalin or Naphthalene Fluorination Products. Physicochemical Foundations of Crystallization of Binary Mixtures of cis- and trans-Perfluorodecalin and Perfluorobutylcyclohexane

Physical–chemical data on the liquid–solid phase transitions in the binary systems trans-perfluorodecalin (trans-PFD)–cis-perfluorodecalin (cis-PFD), trans-PFD–perfluorobutylcyclohexane (BCH), and cis-PFD–BCH are obtained. All three systems are characterized by the presence of a temperature extremum on the fusibility curve. For the trans-PFD–BCH system, the liquidus line can be described by the equation for simple eutectic systems with the assumed activity coefficient \(\gamma _{i}^{l}\) = 1, which indicates that the behavior of the system is close to ideal. The process of bulk crystallization is considered using the example of a cis‑PFD–BCH mixture. It is demonstrated that from cis-PFD–BCH mixtures with an initial content x_cis-PFD = 0.7348 and 0.6447 mol. fr., cis-PFD can be isolated with a purity of more than 0.99 mol. fr. in three crystallization cycles.