Electrical Conductivities, Viscosities, and Densities of N-Acetoxyethyl-N,N-dimethyl-N-ethylammonium and N,N-Dimethyl-N-ethyl-N-methoxyethoxyethylammonium Bis(trifluoromethanesulfonyl)amide and Their Nonfunctionalized Analogues

摘要

The temperature dependences of the density, viscosity, and electrical conductivity were investigated in four ammonium ionic liquids with the bis(trifluoro-methanesulfonyl)amide anion ([Tf2N]"). The cations for the ionic liquids were N-acetoxy-ethyl-N,N-dimethyl-N-ethylammonium ([N_(112,2OCO1)]~+), N,N-dimethyl-N-ethyl-N-meth-oxyethoxyethylammonium ([N_(112,2OCO1)]~+), N,N-dimethyl-N-ethyl-N-pentylammonium ([N_(1125)]~+), and N,N-dimethyl-N-ethyl-N-heptylammonium ([N_(1127)]~+). Measurements were performed over the temperature range T = (273.15 to 363.15) EC at atmospheric pressure. The densities were fitted to quadratic functions of temperature. The ionic liquids with the functionalized cations ([N_(112,2OCO1)]~+ and [N_(112,2OCO1)]~+) have the higher densities than the corresponding counterparts with the nonfunctionalized cations ([N_(1125)]~+ and [N_(1127)]~+). The viscosities and electrical conductivities were analyzed using the Litovitz and Vogel-Fulcher-Tamman equations. The ester functionalized ionic liquid, [N_(112,2OCO1)]-[Tf2N], has poorer transport properties (that is, higher viscosity and lower electrical conductivity) than the nonfunctionalized [N_(1125)][Tf2N], whereas the ether functionalized ionic liquid, [N_(112,2OCO1)][Tf2N], has superior transport properties to its analogue, [N_(1127)][Tf2N]. Empirical Walden plots (double logarithmic graph of molar conductivity vs reciprocal viscosity) give straight lines with slopes less than unity.