Volumetric Behavior of Binary Mixtures of Tetrahydrofuran and C1-C4 Alkoxyethanols at Different Temperatures

The volumetric behavior of binary mixtures of tetrahydrofuran (THF) +2-methoxyethanol (2-MeOEtOH), + 2-ethoxyethanol (2-EtOEtOH) and 2-butoxyethanol (2-BuOEtOH) were studied at 293.15, 298.15 and 303.15 K to identify the types and strengths of intermolecular interactions taking place in the solvent systems. The densities, ρ, of the pure solvents and the binary mixtures ranging from 0.0003-0.9997 of THF were obtained at the working temperatures. Excess molar volumes, V, of the binary mixtures were calculated from the density data. The calculated excess molar volumes were fitted into the Redlich-Kister polynomial and the fitting coefficients, Ai, obtained. The values of excess molar volumes were negative in all the solvent systems and at all temperatures in the mole fraction region of0.00-0.50 THF. Beyond the mole fraction region of 0.50, the excess molar volumes were slightly positive. The negative excess molar volumes in the region of low THF concentration are attributed to intermolecular hydrogen bonding between unlike molecules of THF and the alkoxyethanols. The magnitudes of the negative excess molar volumes were also found to be dependent upon the chain length of the alkoxy group and the temperature. The results show that the excess molar volumes become more negative when the chain length of the alkoxy group increased and this was attributed to the relative proton-donating ability of the alkoxyethanols investigated.