Thermodynamics of mixtures containing alkoxyethanols. Part XXII. Densities, excess molar volumes, speeds of sound and isothermal compressibilities for 2-(2-alkoxyethoxy)ethanol + dibutylether systems at 293.15, 298.15 and 303.15 K

Abstract

Densities, ρ, and speeds of sound, u, of systems formed by 2-(2-methoxyethoxy)ethanol (22MEE), 2-(2-methoxyethoxy)ethanol (22EEE) or 2-(2-butoxyethoxy)ethanol (22BEE) and dibutylether (DBE) have been measured at 293.15, 298.15 and 303.15 K and atmospheric pressure using a vibrating-tube densimeter and sound analyser Anton Paar model DSA-5000. The ρ and u values were used to calculate excess molar volumes, V E, and deviations from the ideal behaviour of the thermal expansion coefficient, Δ α P, or of the isentropic and isothermal compressibilities, Δ κ S and Δ κ T, respectively. Molar excess isochoric magnitudes, internal energies and heat capacities have been also estimated. V E decreases with the size of the 2-(2-alkoxyethoxy)ethanol as the strength of the interactions between hydroxyether molecules decreases in the same order. Systems involving 22MEE or 22EEE are characterized by positive V E values, which suggests that the main contribution to this excess function comes from the disruption of the interactions between cellosolve molecules. Negative V E values, over the whole mole fraction range, are encountered for the 22BEE mixture due to structural effects that are predominant in this system. Dipolar interactions become weaker when the chain length of the hydroxyether increases along a homologous series. For solutions containing homomorphic hydroxyethers with different numbers of etheric atoms the molar excess enthalpy, H E, and V E are higher for those mixtures with the larger number of etheric atoms, indicating that dipolar interactions become stronger when the number of oxyethylene groups in the alkoxyethanol increases. In contrast, compressibility decreases at these conditions.