Correlation and Estimation of Aqueous Solubilities of Halogenated Benzenes

Abstract
Quantitative structure-activity relationships have been studied for the aqueous solubility of 42 halogenated benzenes (HBs) at 25°C. Multiple regression correlations of aqueous mole fraction solubility (X) with molecular size descriptors (total molecular surface area, total group surface area, molecular volume or molecular weight), melting point temperature (MP) and a combined molecular symmetry and structure descriptor (R. Molecular size descriptor) are reported. A generalized correlation takes the form of log X = a0 + a1 (Molecular size descriptor)n + a2 (MP—25) + a3 (R. Molecular size descriptor) in which 1 ≤ n ≤ 2, ai refers to the ith regression coefficient and R is a molecular redundancy index. These correlations enable the aqueous solubility to be estimated from melting point temperature and structural information. The best correlation found, from the standpoint of reduced standard deviation and calculational simplicity, does not contain a melting point term (a2 = 0). Agreement between observed and estimated solubilities is quite good. More importantly, the correlations did provide very reasonable predictions for the 7 fluorobenzenes which were measured as part of this investigation, but not included in the regression analysis. The correlations may also be useful in screening experimental solubility for which serious discrepancies exist in the literature.

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