Volumetric Properties of Nucleic Acid Bases and Nucleosides in Aqueous Ethanol, 1,2-Ethanediol, 2-Propanol, and 2-Methyl-2-Propanol at 25°C

Partial molar volumes of cytosine, uracil, thymine, cytidine, uridine, thymidine, and adenosine have been measured in different concentrations of aqueous ethanol, 1,2-ethanediol, 2-propanol, and 2-methyl-2-propanol at 25°C using densimetry. These data are utilized in conjunction with the partial molar volumes of these nucleic acid bases and nucleosides in water reported earlier to deduce the partial molar volumes of transfer from water to aqueous alcohol or diol. The results are explained in terms of likely solute–solvent interactions; the role of solvent in these interactions is discussed. The partial molar volume data are also used to calculate the contribution of –CH₂- groups in the nucleic acid base or solvent and of ribose in the nucleoside to the partial molar volume of transfer. The validity of group additivity in these systems is discussed.