VOLUMETRIC STUDIES OF CHOLESTEROL IN BASIC AND INERT SOLVENTS FROM 25TO 55-DEGREES-C

The densities of cholesterol solutions in several proton acceptor solv ents (benzonitrile, N,N-dimethylacetamide, N,N-dimethylformamide, N,N, N',N'-tetramethyl-urea, hexamethylphosphoramide, dibutylether, dibutyl amine) and in benzene, n-heptane and 1-heptanol, from 25 to 55 degrees C have been measured. The calculated apparent molar volumes of choles terol are independent of concentration in solution. The standard parti al molar volumes of cholesterol in the solvents whose molecules contai n linear hydrocarbon chains (dibutylether, dibutylamine, n-heptane and 1-heptanol) show considerably lower values than those in the remainin g media. The observed volume contraction is likely to be due to intera ctions of van der Waals type. The measured thermal expansion coefficie nt of cholesterol solutions and of cholesterol in an infinitely dilute solution in all the examined systems, are higher than the thermal exp ansion coefficients of the pure solvents. It has been found that this difference between the limiting thermal expansion coefficients of chol esterol containing systems and that for the pure solvent is affected b y the solvent polarity.