Solubility of pyrazine and its derivatives in supercritical carbon dioxide

Isopleths and solution densities are reported, from approximate to 25 to 100 degrees C and pressures to approximate to 200 bar, for mixtures of CO2 with pyrazine, 2-methoxypyrazine, 2-acetylpyrazine, 2-methylpyrazine, and 2,3-dimethylpyrazine. These five solute + CO2 systems exhibit type-I phase behavior with similar mixture critical pressures up to 100 degrees C. The Peng-Robinson equation of state, with k(ij) equal to zero, provides a semi-quantitative representation of the data for all of the pyrazines with the exception of the 2-acetylpyrazine + CO2 system, which required a k(ij) of -0.100 to get a reasonable representation of the data. The data presented here further substantiates the observation that supercritical CO2 can be used to extract pyrazines from natural materials.