Protic ionic liquids: Properties and applications

Generally, ionic liquids (ILs) are defined as those fused salts with a melting point less than 100°C with salts that has higher melting points referred to as molten salts. However, a view to include all protic ILs (PILs) and protic molten salts with melting point up to 200°C has been initialized. The inclusion of fused salts with higher melting points was to allow structure and property correlations to be made across a wider range of complexes. PILs with stoichiometric ratios of Brøonsted acid to base have also been covered. The ionicity, physicochemical and thermal properties of the PILs including thermal phase behavior, glass transition, melting point, thermal stability, density and molar volume, refractive index and molar refractivity, surface tension, viscosity, ionic conductivity and polarity are covered followed by description of application where they have been used including organic synthesis, chromatography, biological applications, fuel cells, explosives, and recently, industrial lubricants.