Topological and experimental approach to the pressure-temperature-composition phase diagram of the binary enantiomer system d- and l-camphor.

In 1981, Jacques, Collet, and Wilen already put forward the idea to use pressure to influence equilibria in binary enantiomer systems in analogy with temperature (Jacques et al. Enantiomers, Racemates and Resolutions; John Wiley & Sons: New York, 1981). Whereas temperature is used routinely to study phase equilibria, pressure is an all but forgotten parameter. This is therefore possibly the first paper on the influence of pressure on a binary enantiomer system: d- and l-camphor. The study consists of two parts, a topological approach, which uses data obtained from routine measurements (differential scanning calorimetry, X-ray diffraction), and the experimental determination of phase transitions as a function of pressure and temperature. This has resulted in two topological pressure-temperature phase diagrams of the pure enantiomer d-camphor and of the racemic mixture dl-camphor; both have been verified by the experiments as a function of pressure. In turn, these results have been used to construct part of the pressure-temperature-composition phase diagram of d- and l-camphor. A method to obtain the excess Gibbs energy from these binary phase diagrams as a function of pressure is proposed.