Structure and hydrogen bonding in binary mixtures of N,N-dimethylformamide with some dipolar aprotic and protic solvents by dielectric characterization

Abstract

The low frequency limit static dielectric constant, optical frequency dielectric constant, excess dielectric constant, and the Kirkwood correlation factor of the binary mixtures of N,N-dimethylformamide with water, ethyl alcohol, ethylene glycol, glycerol, dimethyl sulphoxide, acetone and 1,4-dioxane over the entire composition range are investigated at 30^oC. The values of these functions emphasize strong N,N-dimethylformamide-water hydrogen bond interaction due to breaking of water tetrahedral structure, whereas the N,N-dimethylformamide-alcohols complexations show a strong hydroxyl group number dependence with enhancement in the structural ordering of alcohols. The dielectric functions of N,N-dimethylformamide-water and N,N-dimethylformamide-1,4-dioxane mixtures reveal the similarity in the complexes, although the N,N-dimethylformamide-water interactions are stronger. The excess functions confirm the weak hydrogen bond interactions of N,N-dimethylformamide with dimethyl sulphoxide and acetone. The pronounced deviation in the excess functions of the studied mixtures confirms the formation of a stable adduct of stoichiometric ratio 1:1 in these systems.