Dielectric relaxation and dipole moment of N,N-dimethylformamide in benzene, dioxane and carbon tetrachloride solutions from microwave absorption studies

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Abstract
Using standing-wave techniques, the dielectric constant ( epsilon ') and the dielectric loss ( epsilon ") of dilute solutions of N,N-dimethylformamide (DMF) in benzene, dioxane and carbon tetrachloride have been measured at 9.987 GHz at 25, 35, 45 and 55 degrees C. Following the single-frequency concentration variational method, the dielectric relaxation time ( tau ) and the dipole moment ( mu ) at various temperatures (25, 35, 45 and 55 degrees C) have been evaluated. From these studies the monomer structure of DMF in various solutions (benzene, dioxane and carbon tetrachloride) has been inferred and for a DMF-in-benzene solution a solute-solvent type of molecular association has been found. The energy parameters ( Delta Fepsilon , Delta Hepsilon and Delta Sepsilon ) for the dielectric relaxation of DMF in benzene, dioxane and carbon tetrachloride solutions have been calculated and compared with the corresponding viscosity parameters. A comparison between these two sets of parameters shows that the dielectric relaxation, like the viscous flow, can be considered as a rate process.