Thermochemical and vapor pressure behavior of anthracene and brominated anthracene mixtures

The present work concerns the thermochemical and vapor pressure behavior of the anthracene (1) + 2-bromoanthracene (2) and anthracene (1) + 9-bromoanthracene (3) systems. Solid–liquid equilibrium temperature and differential scanning calorimetry studies indicate the existence of a minimum melting solid state near an equilibrium temperature of 477.65 K at x1 = 0.74 for the (1) + (2) system. Additionally, solid–vapor equilibrium studies for the (1) + (2) system show that the vapor pressure of the mixtures depends on composition, but does not follow ideal Raoult's law behavior. The (1) + (3) system behaves differently from the (1) + (2) system. The (1) + (3) system has a solid solution like phase diagram. The system consists of two phases, an anthracene like phase and a 9-bromoanthracene like phase, while (1) + (2) mixtures only form a single phase. Moreover, experimental studies of the two systems suggest that the (1) + (2) system is in a thermodynamically lower energy state than the (1) + (3) system.

► We report on phase and thermochemical behavior of two binary polycyclic aromatic compound mixture systems. ► The influence of mono bromo substitution position on mixture properties was examined. ► Solid vapor pressures for these mixtures were measured using Knudsen effusion method. ► Anthracene + 2-bromoanthracene mixtures form a single phase, while anthracene + 9-bromoanthracene mixtures form two phases.