Determination and correlation of the solubility of four Brønsted-acidic ionic liquids based on benzothiazolium cations in six alcohols

• Solubility of four acidic benzothiazolium cations-based ILs was measured.
• The solubilities vary with the polarity of the solvent.
• The solubility of some ILs is with “temperature-sensitive” property.
• The measured solubilities were correlated by Apelblat model and λh model.
• The dissolution enthalpy and entropy of ILs were calculated using the van’t Hoff equation.

Solubilities of four acidic ionic liquids based on benzothiazolium cations in six alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol and 2-methyl-1-propanol) from at temperatures from (253 to 384) K were determined using a static equilibrium method under atmospheric pressure. The modified Apelblat equation and λh equation were employed to correlate the experimental data with good agreement. The solubilities of ILs increase with increasing temperature. It is interesting to find that the solubility of some ILs in alcohols are with “temperature-sensitive” properties. The solubility is related with the polarity and molecular structures of the solvent, as well as the strength of hydrogen bonding between alcohols and anionic groups of ILs. The dissolution enthalpy and entropy of ILs were calculated by the van’t Hoff equation. This study provides useful information for further research and application of the ionic liquids.