Synthesis and properties of switchable polarity ionic liquids based on organic superbases and fluoroalcohols

• Polarity of SWILs can be switched by CO2.
• SWILs were synthesized via proton transfer reaction.
• CO2 absorption promotes formation of free ions in SWILs.
• Low polar solute can be separated from SWILs.

Switchable polarity ionic liquids (SWILs) with low moisture sensitivity were successfully synthesized from organic amidine/fluoroalcohol and guanidine/fluoroalcohol via proton transfer reaction. The ionic liquids showed low polarity and could be converted into high-polarity fluoroalkylcarbonate ILs upon the treatment with CO2 under mild conditions. Their high polarity state could also readily be reverted to the low polarity state by the removal of CO2 with heating. Changes in the structures and physical properties resulting from the change from low polarity to high polarity were confirmed by NMR spectroscopy, FTIR spectrophotometry, UV–vis spectroscopy, and conductivity and miscibility measurements. These SWILs have potential applications in solute separation and solvent recovery.

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