Dielectric relaxation study of binary and ternary diol(s)/mono-alcohol mixtures in cyclohexane

• Published in: Journal of molecular liquids 2000-12, Vol.89 (1), p.57-79
• Main Authors: Hanna, F.F., Saad, A.L.G., Youssef, M.H., Soliman, A.
• Format: Article
• Language: English
• Subjects: alcohols; Dielectric spectroscopy; diols; hydrogen bonding and ternary mixtures; non-polar solvent
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/S0167-7322(00)90005-9

The dielectric relaxation of binary and ternary diol(s)/monohydric alcohol diluted with a non-polar solvent (cyclohexane) has been studied. Different diols of different chain lengths and OH groups positions and three mono-alcohols namely n-butanol, n-hexanol and cyclohexanol are used. The relaxation spectra have been analyzed in two Debye terms. The predominating term is related to the association process. Its variation with the viscosity η is also considered. A good correlation exists between dielectric parameters and the number density of dipoles N D for ternary and quaternary mixtures of the same alcoholic concentration X in mol. Values of S R/N D (which is proportional to the dipole moment μ), relaxation time τ 1 and relaxation strength G 1 increase with the increase in concentration N D as well as the diols chain length, with the exception of those having the OH- group in the positions 1,2. They have low values which could be due to intramolecular hydrogen bonding. This may lead to the conclusion that the two OH- groups are close to each other so that intramolecular hydrogen bonding could occur.