SOLVATOCHROMIC PARAMETERS AND SOLUBILITIES IN SUPERCRITICAL-FLUID SYSTEMS

Spectroscopic studies of the compound 2-nitroanisole in supercritical fluids CO2 and N2O show that pi values vary linearly with density. Th e solubility trends in these single component supercritical fluid solv ents qualitatively followed the trends in solvent power predicted from pi. However, the relative solvent power predicted for CO2 and N2O ba sed on pi resulted in an opposite order to what was determined experi mentally through solubility measurements. The pi parameter may be of some use for solubility prediction if only a limited set of solute-sol vent systems are considered. Measurements of pi, especially those in binary supercritical fluid solvents, suggest that pi could be a valua ble tool for probing the solute-organized cybotactic region.