A new correlation of solubilities of azoic compounds and anthraquinone derivatives in supercritical carbon dioxide

Solubilities of azoic compounds and anthraquinone derivatives in supercritical carbon dioxide were correlated with a new semiempirical equation and five equations taken from literature. All solutes are dyestuffs or compounds with a molecular structure similar to dyestuffs. The equations were applied to literature solubility data [J. Supercrit. Fluids 21 (2001) 1; J. Supercrit. Fluids 13 (1998) 37; Fluid Phase Equilib. 158–160 (1999) 707; J. Supercrit. Fluids 13 (1998) 43; Talanta 48 (1999) 951; Fluid Phase Equilib. 200 (2002) 31; Fluid Phase Equilib. 194–197 (2002) 895; J. Supercrit. Fluids, in press] and to a new data set of solvent brown 1, experimentally measured by us. Altogether, 16 compounds and over 400 solubility data were considered. In the development of the new correlation, which has three fitting parameters, a dimensionless group was defined: this group, which involves solute molar volume and fusion properties, is a function of solvent density over a significant range of pressures and temperatures. The proposed equation is able to correlate solubility data with good agreement. The mean average absolute percent deviation (AA%D) of the new equation was the lowest among the equations with the same number of fitting parameters.