title: Extended Hildebrand solubility approach: p-hydroxybenzoic acid in mixtures of dioxane and water.
abstract: The extended Hildebrand solubility approach was used to reproduce the solubilities of p-hydroxybenzoic acid in a dioxane-water system. The solubility parameter of p-hydroxybenzoic acid was determined and found to be approximately 15 (cal/cm3)1/2. Residual plots (scattergrams) were used in conjunction with R2, F, and standard deviation values to determine whether a quadratic, cubic, quartic, or higher degree polynomial was required in the calculations. The earlier iteration method for back-calculations of solubilities was replaced by the more reliable root-finder method. The solubility profile of p-hydroxybenzoic acid in dioxane-water mixtures did not follow a log linear relationship even in the ranges where the solubility parameters of the water-cosolvent mixture might be expected to produce a straight-line function, as observed in other studies.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D004146:Dioxanes; D004355:Drug Stability; D062385:Hydroxybenzoates / Q000032:analysis*; D007700:Kinetics; D010226:Parabens; D012995:Solubility; D012997:Solvents; D014867:Water
chemical_list: D004146:Dioxanes; D062385:Hydroxybenzoates; D010226:Parabens; D012997:Solvents; D014867:Water; C025223:1,4-dioxane; C038193:4-hydroxybenzoic acid