Electrical Conductivities, Viscosities, and Densities of N-Methoxymethyl- and N-Butyl-N-methylpyrrolidinium Ionic Liquids with the Bis(fluorosulfonyl)amide Anion

This paper reports the densities, viscosities, and electrical conductivities of the two pyrrolidinium ionic liquids, N-methoxymethyl-N-methylpyrrolidinium bis­(fluorosulfonyl)­amide ([Pyr_1,1O1]­[FSA]) and N-butyl-N-methylpyrrolidinium bis­(fluorosulfonyl)­amide ([Pyr_1,4]­[FSA]), over the temperature range T = (273.15 to 363.15) K at atmospheric pressure. The densities were fitted to polynominals, and the viscosities and electrical conductivities were analyzed with the Vogel–Fulcher–Tammann and Litovitz equations. The densities and electrical conductivities of [Pyr_1,1O1]­[FSA] are higher than those of [Pyr_1,4]­[FSA], while the viscosities of the former salt are smaller than those of the latter. The Walden plots (double logarithm graph of molar conductivity vs fluidity (reciprocal viscosity)) give the straight lines with the slopes being 0.91 to 0.94. The present results for [Pyr_1,1O1]­[FSA] and [Pyr_1,4]­[FSA] are compared with those for the bis­(trifluoromethanesulfonyl)­amide ([NTf₂]⁻) analogues, [Pyr_1,1O1]­[NTf₂] and [Pyr_1,4]­[NTf₂].