Physicochemical Characterization of New Sulfonate and Sulfate Ammonium Ionic Liquids

In this work we describe the synthesis and thermal properties of nine new salts derived from ammonium that incorporate alkanesulfonate and alkanesulfate anions. Their structures were confirmed by H-1 and C-13 NMR and HRMS-ESI. Their thermal properties were determined by differential scanning calorimetry (DSC). Three of the synthesized salts have been shown to be room temperature ionic liquids: N-ethyl-N-(2-hydroxyethyl)-N,N-dimethylammonium butanesulfonate, N-ethyl-N,N-dimethylbutylammonium ethylsulfate, and N-ethyl-N-(2-hydroxyethyl)-N,N-dimethylammonium ethylsulfate. Experimental densities, speeds of sound, dynamic viscosities, and refractive indices of these three ionic liquids were measured at T = 298.15 K.