The values of complex permittivity for alcohol-1,4-dioxane (DX) mixtures with various concentrations have been determined in the frequency range 10 MHz to 20 GHz using the time domain reflectometry (TDR) method. Numbers of hydrogen bonds between alcohol-alcohol and alcohol-dioxane pairs are estimated from the values of the static dielectric constant by using the Luzar model. The model provides a satisfactory explanation of the experimental results related to the static dielectric constant. The binding energies for alcohol-alcohol (pair 11) and alcohol-DX (pair 12) are estimated to be -13.98 and -16.25 kJ/mol, respectively. The results have also been compared with previous results of the ethyleneglycol-DX system.

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The molecular interactions between water and dioxane are studied using hydrogen bonding model and density functional method. The average number of hydrogen bonds obtained using hydrogen bonding model is maximum at 0.83 mole fraction of water in dioxane. This concentration corresponds to five water molecules and a dioxane molecule in a complex [Mashimo et al., J Chem Phys 1992, 96, 6358; Kanse et al., J Ind Chem Soc 2007, 83, 168]. The values of dielectric constant for the mixture obtained by hydrogen bonding model are in excellent agreement with the experimental values. Density functional theory calculations show that the most stable conformer of dioxane-5H 2 O hydrogen bonded complex has six short hydrogen bonds. Number of hydrogen bonds from density functional calculations and hydrogen bonding model are in excellent agreement at 0.83 mole fraction of water. In this hydrogen bonded complex five water molecules bridging the two oxygen atoms of dioxane molecule and thus is a cyclic structure, which is also in agreement with the experiment.

Complex dielectric permittivity measurements of 1,2-propanediol-1,4-dioxane mixtures has been carried out at different concentration and in the frequency range of 10 MHz to 20 GHz using time domain reflectometry (TDR). The least squares fit method has been used to obtain the static dielectric constant, relaxation time, and Bruggeman factor for binary mixtures. The Kirkwood-Frohlich theory is applied to compute the dielectric constant for the mixtures. It adequately reproduces the experimental values of static dielectric constants for the 1,2-propanediol-dioxane mixtures. The excess parameters confirm that the heteromolecular hydrogen bonding interactions between 1,2-propanediol and dioxane molecules vary significantly in the mixture. The Bruggeman model for the nonlinear case has been fitted to the experimental dielectric data for mixtures.

A time-domain reflectometry technique has been used to measure complex dielectric permittivity ε*(ω) = εʹ(ω) − jε″(ω) of 1-propanol-dioxane, 2-propanol-dioxane, aniline-dioxane, N-methylaniline-dioxane and N,N-dimethylaniline-dioxane mixtures in the frequency range of 10 MHz to 30 GHz. The complex permittivity spectrum has been fitted with a single relaxation time with a small amount of Davidson-Cole behaviour. The least squares fit method has been used to obtain the static dielectric constant (ε 0 ), relaxation time (τ), Bruggeman factor and Kirkwood correlation factor. The Luzar theoretical model is used to compute the binding energies and average number of hydrogen bond between co-solvent-co-solvent and co-solvent-dioxane molecules.