Crystallization of an organic compound from an ionic liquid using carbon dioxide as anti-solvent

In this paper the anti-solvency behavior of supercritical carbon dioxide (CO2) as a way to recover an organic compound from an ionic liquid by crystallization is explored. As an example, the conditions for crystallization of the organic compound methyl-(Z)-a-acetamido cinnamate (MAAC) from the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim+][BF4-]) using supercritical CO2 as anti-solvent are studied experimentally by measuring the phase behavior of the ternary system [bmim+][BF4-] + CO2 + MAAC. MAAC can be recovered from [bmim+][BF4-] by either using a shift to higher CO2 concentrations at constant temperature (anti-solvent crystallization) or by using a shift to lower temperatures at constant CO2 concentration (thermal shift)