Dielectric Relaxation Studies of Binary Mixtures of N,N-Dimethylformamide and N,N-Dimethylacetamide in Benzene Solutions Using Microwave Absorption Technique

Abstract

Using standard microwave X-band technique and by following Gopalakrishna’s single frequency concentration variational method, dielectric relaxation times (τ) of dilute solutions of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA) and several DMF+DMA mixtures in benzene at 15°C have been measured. Such measurements using DMF+DMA mixture containing 50 mol%DMA have also been carried out in benzene at 20, 25 and 30°C. The energy parameters (ΔF_ε, ΔH_ε and ΔS_ε) for the dielectric relaxation process for DMF+DMA mixture containing 50 mol%DMA have been calculated at 15, 20, 25 and 30°C and compared with the corresponding viscosity parameters. A good agreement between the free energy of activation from these two sets of values shows that dielectric relaxation process, like viscous flow, can also be treated as a rate process. From relaxation time behaviour of DMF and DMA binary mixture in benzene solution, solute-solute type of molecular association is proposed.