Density, Viscosity, and Electrical Conductivity of Protic Amidium Bis(trifluoromethanesulfonyl)amide Ionic Liquids

We investigated the densities, viscosities, and electrical conductivities of the protic amidium-based ionic liquids with bis(trifluoromethanesulfonyl)amide ([TFSA]−). The cations were N,N-dimethylformamidium, [DMFH]+, N,N-dimethylacetamidium, [DMAH]+, and N,N-dimethylpropionamidium, [DMPH]+. The physical properties were measured over the temperature range from 273.15 to 363.15 K at atmospheric pressure. The densities were correlated with the linear or quadratic equations, and the transport properties were reproduced well with the Vogel–Fulcher–Tammann equation. The densities and the viscosities increased in the following order: [DMAH][TFSA] > [DMPH][TFSA] > [DMFH][TFSA]. The opposite trend was observed for the electrical conductivities. The empirical Walden plots gave the straight lines in all the present ionic liquids. It was found that the data points for [DMFH][TFSA] appreciably fall below [DMPH][TFSA] and [DMAH][TFSA] on the Walden plot.