Density, viscosity and electrical conductivity of protic alkanolammonium ionic liquids

Abstract

Ionic liquids are molten salts with melting temperatures below the boiling point of water, and their qualification for applications in potential industrial processes does depend on their fundamental physical properties such as density, viscosity and electrical conductivity. This study aims to investigate the structure-property relationship of 15 ILs that are primarily composed of alkanolammonium cations and organic acid anions. The influence of both the nature and number of alkanol substituents on the cation and the nature of the anion on the densities, viscosities and electrical conductivities at ambient and elevated temperatures are discussed. Walden rule plots are used to estimate the ionic nature of these ionic liquids, and comparison with other studies reveals that most of the investigated ionic liquids show Walden rule values similar to many non-protic ionic liquids containing imidazolium, pyrrolidinium, tetraalkylammonium, or tetraalkylphosphonium cations. Comparison of literature data reveals major disagreements in the reported properties for the investigated ionic liquids. A detailed analysis of the reported experimental procedures suggests that inappropriate drying methods can account for some of the discrepancies. Furthermore, an example for the improved presentation of experimental data in scientific literature is presented.

Triethylene glycol based deep eutectic solvents and their physical properties

“…Walden rule is often obeyed well empirically, especially by solutions of large and only weakly coordinating ions in solvents with nonspecific ion-solvent interactions [26]. The Walden rule relates the mobility of ions to the fluidity of their surrounding medium according to following equation [27]:…”

Tertiary and Quaternary Ammonium-Phosphate Ionic Liquids as Lubricant Additives

“…More recently, ammonium-based ILs have been examined as neat lubricants or additives [15,[30][31][32][33][34][35]. Other recent work has revealed the merits of protic ILs [36][37][38][39][40][41].…”

Physicochemical and Acid-base Properties of a Series of 2-Hydroxyethylammonium-based Protic Ionic Liquids

“…[33][34][35][36][37] In order to clarify solvent natures, one must have extensive knowledge of physicochemical and Brønsted and/or Lewis acid-base properties of ionic liquids. Experimental results for the physicochemical properties [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52] and solvatochromic parameters [53][54][55] of ionic liquids with the hydroxyl groups have been reported.…”