Studies on Hydrogen-Bond Interactions in Ternary Mixtures of Polar Solvents by Dielectric Constant Measurements

Abstract

The static dielectric constant of equimolar mixtures of formamide + N, N-dimethylformamide and formamide + 2-aminoethanol mixed with water, ethyl alcohol, dimethylsulphoxide, and 1,4-dioxane were measured over the entire composition range at 303.15 K. The concentration-dependent non-linear behavior of the dielectric constant of the ternary mixtures confirms the formation of hydrogen-bond interactions between the mixture constituents. The excess dielectric-constant values of the mixtures were determined and discussed in view of the strength of hydrogen-bond interactions and the nature of dipolar ordering. It is found that in ternary mixtures, water acts as a structure-maker and ethyl alcohol, dimethylsulphoxide, and 1,4-dioxane act as structure-breakers for the equimolar formamide + N,N-dimethylformamide and formamide + 2-aminoethanol binary structures.