Dipole moments of mono-, di-, tri- and tetra(oxyethylene) glycol in 1,4-dioxane and benzene solutions at 298.15 K

The permittivity of 1,4-dioxane and benzene solutions of mono(oxyethylene) glycol, MEG, di(oxyethylene) glycol, DEG, tri(oxyethylene) glycol, TEG and tetra(oxyethylene) glycol, TTEG was measured at 298.15 K. From the experimental data, the apparent molar polarizations at infinite dilution were calculated. The limiting apparent molar polarization for a definite compound depends on the theoretical model used and is the highest for the Kirkwood model relative to the Debye or Onsager approach. The electric dipole moment of the investigated solutes was estimated according to the Debye, Onsager and Kirkwood theoretical approaches. The calculated dipole moments (Debye method) linearly increase with the square root of the number of monomeric units, while the Onsager dipole moments do not show a simple linear relation. The Kirkwood correlation factor depends on the molecular weight of the solute and is close to one. From the group dipole moment of the polar monomeric unit the factor g, which takes into account the degree of flexibility of the chain, was calculated and found to be greater than one for the lower members. (C) 2003 Elsevier B.V. All rights reserved.