Pressure-induced phase separation of miscible liquids: 1: 1 n-pentane/iso-pentane

We report the unexpected pressure-induced and time-dependent nucleation and crystallisation of n-pentane from a 1 : 1 mixture of n-pentane and iso-pentane. The crystal structure of n-pentane at 3.3 GPa is reported; the 19.6% decrease in volume up to 3.3 GPa is caused by the significant reduction of voids within the structure. The study has wider implications for the separation of mixtures of organic compounds that have similar melting and boiling points, as well as the use of a 1 : 1 mixture of n-pentane and iso-pentane as a pressure-transmitting medium in high-pressure diffraction experiments.