Solubility In Binary Solvent Mixtures Research Articles

Thermochemical Investigations of Associated Solutions: 4. Calculation of Carbazole–Dibutyl Ether Association Constants from Measured Solubility in Binary Solvent Mixtures

Experimental solubilities are reported for anthracene and carbazole in binary dibutyl ether plus n-hexadecane and dibutyl ether plus squalane solvent mixtures at 25°C. Results of these measurements, used in conjunction with the extended nearly ideal binary solvent (NIBS) model, enabled calculation of the carbazole-dibutyl ether association constant. The numerical value obtained was independent of the hydrocarbon cosolvent, and compared favorably with previously reported values based on carbazole solubilities in solvent mixtures containing much smaller alkane cosolvents.

Thermochemical investigations of associated solutions. II. Calculation of iodine-benzene equilibrium constants from solute solubility in binary solvent mixtures

Solubilities have been determined at 25 °C for iodine in binary mixtures of benzene with n-hexane, n-heptane and isooctane. The results of these measurements are compared to solution models previously developed for solubility in systems containing only non-specific interactions and to models assuming solute-solvent complexation. The Nearly Ideal Binary Solvent Model (NIBS) based entirely on non-specific interactions provides rather poor predictions of the iodine solubilities, with some of deviations greater than 25%. In comparison, a 1:1 solute-solvent complexation model describes the experimental solubilities to within a maximum deviation of 6%, An example is presented to illustrate the calculation of association constants from solubility measurements.

Extended hildebrand solubility approach: Solubility of theophylline in polar binary solvents

A quantitative approach is presented for predicting solubilities of crystalline compounds in binary solvent systems. The solubility of theophylline in mixed solvents consisting of dioxane and water was determined at 25 ± 0.1°. The solubilities across this range of polar solvents were back-calculated using a technique involving an interaction energy term, W. This parameter is regressed against a polynomial expression in δ1, the solubility parameter for the mixed solvents. Except for the end-points, solubilities were predicted within <12% and with considerably better accuracy in most cases. The new approach modifies the well-known Hildebrand solubility equation to make it applicable to polar systems. Although the method may be used with solutes in pure solvents, its greatest application appears to be the prediction of drug solubility in binary solvent mixtures.