Thermodynamic study of organic compounds in di-n-butyl ether. Enthalpy and Gibbs energy of solvation

Abstract

The Gibbs energies and enthalpies of solvation of some hydrocarbons (n-hexane, n-octane, cyclohexane), alcohols (methanol, propan-1-ol, butan-1-ol, butan-2-ol), ethers (diethyl ether, tetrahydrofuran), ketones (propanone, pentan-3-one, cyclopentanone), amines (n-propylamine, n-butylamine), and acetonitrile in di-n-butyl ether have been determined at 298.15 K from vapour–liquid equilibrium measurements and from limiting enthalpies of solution. The data obtained have been compared with the corresponding values of the solvation functions in octan-1-ol and hexadecane. The phenomenology has been discussed in terms of a simple group additivity scheme. The interaction effects of polar and non-polar groups with the solvents have been deduced from the above group contributions combined with the cavity terms estimated through the scaled particle theory. The linear solvation energy relationships (LSER) have also been used for correlating the thermodynamic solvation function to the structural features of the solutes. All the approaches consistently highlight that the hydrophobic groups exhibit interactions with the solvent of nearly the same strength in the three media, while clearly different interactions are shown by polar groups.