Effect of aqueous hydrochloric acid and zwitterionic betaine on the mutual solubility between a protic betainium-based ionic liquid and water

Abstract The solubility of hydrophobic betainium bis (trifluoromethylsulfonyl)imide ionic liquid in an aqueous phase with controlled acidity has been investigated by a standard liquid–liquid extraction technique. The effect of zwitterionic betaine added into the aqueous phase has also been studied. Quantitative NMR was employed to characterize the distribution behavior of the ionic liquid constituents between the two phases. A mathematical model to describe the ionic liquid solubility in the aqueous phase was developed. This approach was utilized to estimate the conditional solubility product constant of the ionic liquid. The possibility of the transfer of some dissociation products back into the organic phase was investigated.