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

Enthalpy of Solvation Correlations for Gaseous Solutes Dissolved in Water and in 1-Octanol Based on the Abraham Model

“…Our method of eq 10 is quite comparable and predicts the enthalpies of solvation compounds in 1-octanol to within a standard deviation of 2.66 kJ/mol using just five independent variables. Bernazzani et al 32 …”

“…In Table S2 (Supporting Information) are collected values of the enthalpies of solvation in octanol for 138 compounds. 22,[31][32][33]42,[49][50][51][52][62][63][64][65] Application of the general eqs 1 and 2 leads to eqs 10 and 11.…”

“…Our search of the chemical literature found compilations of enthalpy of solvation data for 456 and 89 solutes dissolved in water 22,24 and 1-octanol, [31][32][33] respectively, plus several papers that reported experimental partial molar enthalpies of solution of liquid and crystalline organic compounds. The latter data were determined by either direct calorimetric methods or calculated on the basis of the temperature dependence of measured infinite dilution activity coefficient data, and the published values were converted to gas-to-water and/or gas-to-octanol enthalpies of transfer by subtracting the solute's standard molar enthalpy of vaporization, 70 ∆ Vap H 298K°, or standard molar enthalpy of sublimation, 71 ∆ Sub H 298K°, at 298.15 K.…”

“…Plyasunov and co-workers [26][27][28][29][30] have also set out fragmentation schemes for ∆ Solv H W°, but these are restricted to specific compounds (for example, aliphatic esters or aliphatic ethers). As regards the correlation of ∆ Solv H OTOH°v alues, only Bernazzani et al 31,32 have reported any scheme, and that for a limited number of compounds only.…”

Volumetric properties of (an organic compound + di-n-butyl ether) atT= 298.15 K

“…Moreover, the system (DBE + tetrahydrofuran), as well as the previously investigated (DBE + cyclohexane), (11) displays positive values of V E m , which can be explained by the destruction of DBE orientational order when this long-chain ether is mixed with an "order destroyer" such as a cyclic molecule. (25) It is worth noting that all systems examined here exhibit positive H E m and G E m values, (6,26) thus indicating a net destruction of the order present in the pure liquids, while negative V E values displayed by (DBE + methanol, or butanol, or diethyl ether, or cyclopentanone, or acetonitrile) indicate a more ordered structure in solution. These apparently conflicting results are difficult to explain.…”