Aqueous Biphasic Systems of Pyrrolidinium Ionic Liquids with Organic Acid-Derived Anions and K₃PO₄

Abstract

Aqueous biphasic systems based on ionic liquids (ILs) have been researched as promising extraction and purification routes for a huge diversity of compounds. The inherent tunability offered by ILs combined with the large variety of salts available underlines the reliable phase equilibrium data. In this vein, this work presents novel aqueous biphasic systems based on the 1-butyl-1-methylpyrrolidinium cation combined with anions derived from organic acids, such as acetate, trifluoroacetate, hexanoate, adipate, and one halogenated anion, bromide, in the presence of a powerful salting out species, the inorganic salt K3PO4. The capacity of these ILs to undergo phase separation is discussed in regard to the chemical structure of the IL anion. The results here obtained were compared with those determined for poly­(ionic liquid) analogues, and it was observed that while in ILs the hydrophobicity of the anion has the major role in phase splitting, in poly­(ionic liquid)­s that role is played by the polymer molecular weight. The effect of temperature on the phase equilibria is addressed.

Up/Down Tuning of Poly(ionic liquid)s in Aqueous Two‐Phase Systems

“…For instance, the use of PILs can avoid the toxicity of small-molecule ILs. [17] Considering the outstanding design flexibility of PILs, superior extraction characteristics [18] and versatile stimuli responses [19] can be easily achieved using PIL-based ATPSs. However, PIL-based ATPSs with tunable phase-separation performance have not been extensively reported.…”

Aqueous Biphasic Systems Containing Customizable Poly(Ionic Liquid)s for Highly Efficient Extractions

“…Poly(ionic liquid)s (PILs) are more promising candidates than ILs for the development of ideal ABSs owing to their better structural flexibility . However, there are few reports of PIL‐based ABSs because common PILs synthesized through free radical polymerization have high molecular weights and wide molecular weight distributions, which lead to poor water solubility, precipitation problems and low to moderate extraction performance.…”

Separation and determination of tetracycline hydrochloride in real water samples using binary small molecule alcohol‐salt aqueous two‐phase system coupled with high‐performance liquid chromatography

“…The application of polymer‐polymer and polymer‐salt ATPS has been restricted as their shortcomings such as high viscosity, difficulty in phase separation, and easily emulsify. IL is expensive and just mainly used on the separation and purification of imidazoles and pyridine antibiotics . At present, the small molecule alcohol‐salt ATPS has been applied in different domains of chemistry because of its advantages of low cost, low viscosity, simple operation, and good biocompatibility.…”

“…IL is expensive and just mainly used on the separation and purification of imidazoles and pyridine antibiotics. 26,27 At present, the small molecule alcohol-salt ATPS has been applied in different domains of chemistry because of its advantages of low cost, low viscosity, simple operation, and good biocompatibility. But unitary ATPS composed of one small molecular water-miscible organic solvent and salt cannot effectively adjust the polarity of the aqueous two-phase, and the object solute cannot quickly enter the organic phase.…”