Dielectric characterization and molecular interaction behaviour in binary mixtures of amides with dimethylsulphoxide and 1,4-dioxane

Abstract

Hydrogen bond molecular interactions and dipolar ordering in binary mixtures of amides (N-methylformamide (NMF), formamide (FA), N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA)) with dimethylsulphoxide (DMSO) and 1,4-dioxane (Dx) have been investigated by dielectric measurements at 30 °C. The static dielectric constant, high frequency limit dielectric constant, excess dielectric constant, effective Kirkwood correlation factor, and corrective Kirkwood correlation factor of the binary mixtures over the entire concentration range were determined to explore the effect of substituted and unsubstituted amides on hetero-molecular interactions. Results confirm that the unlike molecule hydrogen bond interaction strength is comparatively 1.5 times stronger in amides–Dx mixtures as compared to the amides–DMSO mixtures, which vary linearly with the values of dielectric constant and Kirkwood correlation factor of pure amides. Dielectric studies inferred 2:1 complexation of NMF to DMSO/Dx, whereas other amides–DMSO and amides–Dx mixed solvents form most likely 1:1 complexes.