Densitometric determination of the solubility parameter and molal volume of compounds of medicinal relevance.

A procedure is described for the simultaneous determination of molal volumes (v02) and solubility parameters (delta) of compounds of medicinal interest. These include alkanoic acids of various chain length and branching (some solid at room temperature), cholesterol, and cholesteryl esters. The procedure is based on the determination of partial molal volumes (v2) from high-precision density measurements of dilute solutions of these compounds in reference solvents, which range in polarity from carbon tetrachloride (delta = 8.6) to nitrobenzene (delta = 10.0). In some cases, the present results do not agree with values of delta published in the literature. Values calculated from group contributions proposed by other authors are prone to error particularly in the case of branched acids and cholesteryl esters.