Volumetric studies of cholesterol in basic and inert solvents from 25 to 55�C

Abstract

The densities of cholesterol solutions in several proton acceptor solvents (benzonitrile, N,N-dimethylacetamide, N,N-dimethylformamide, N,N,N',N'-tetramethylurea, hexamethylphosphoramide, dibutylether, dibutylamine) and in benzene,n-heptane and 1-heptanol, from 25 to 55°C have been measured. The calculated apparent molar volumes of cholesterol are independent of concentration in solution. The standard partial molar volumes of cholesterol in the solvents whose molecules contain linear hydrocarbon chains (dibutylether, dibutylamine,n-heptane and 1-heptanol) show considerably lower values than those in the remaining media. The observed volume contraction is likely to be due to interactions of van der Waals type. The measured thermal expansion coefficient of cholesterol solutions and of cholesterol in an infinitely dilute solution in all the examined systems, are higher than the thermal expansion coefficients of the pure solvents. It has been found that this difference between the limiting thermal expansion coefficients of cholesterol containing systems and that for the pure solvent is affected by the solvent polarity.