Excess free energy approach to the estimation of solubility in mixed solvent systems III: Ethanol-propylene glycol-water mixtures.
The reduced three-suffix solubility equation derived from the Wohl excess free energy expression is used to describe the solubility of phenobarbital in propylene glycol-water, ethanol-propylene glycol, and ethanol-water-propylene glycol mixtures and the solubility of hydrocortisone in propylene glycol-water mixtures. Solvent-solvent interaction constants were obtained by fitting total vapor pressure versus composition data, obtained at 25 +/- 0.1 degrees C, to the Wohl excess free energy model for the solvents. The equation describes solubility in these systems satisfactorily except for phenobarbital in ethanol-propylene glycol, where the solubility is fairly high and assumptions involved in the derivation of the equation do not hold.
D055598:Chemical Phenomena; D002627:Chemistry, Physical; D000431:Ethanol; D006854:Hydrocortisone; D008956:Models, Chemical; D010634:Phenobarbital; D011409:Propylene Glycols; D012995:Solubility; D013816:Thermodynamics; D014867:Water
D011409:Propylene Glycols; D014867:Water; D000431:Ethanol; D006854:Hydrocortisone; D010634:Phenobarbital