Preparation and Hydrophilicity/Lipophilicity of Solubility-Switchable Ionic Liquids

Abstract

Various solubility-switchable ionic liquids were prepared. Their syntheses were readily achieved in a few steps from glyceraldehyde dimethylacetal or its derivatives. Pyridinium, imidazolium, and phosphonium derivatives also exhibited solubilityswitchable properties; acetal-type ionic liquids were soluble in organic solvents, while diol-type ones exhibited a preference for being dissolved in the aqueous phase. The solubility of the ionic liquids prepared in this study also depended on the number of carbon atoms in the cationic parts of the ionic liquids. Interconversion between the diol-type and the acetal-type ionic liquids was readily achieved under the standard conditions for diol acetalization and acetal hydrolysis. One of the prepared ionic liquids was also examined as a solvent for an organic reaction.

Ionic Liquids for the Chemical Recycling of Polymeric Materials and Control of Their Solubility

“…Ammonium-, phosphonium-, imidazolium-, and pyridinium-type solubility-switchable ionic liquids (SSILs) were prepared from commercially available glycerol acetal or glycelaldehyde acetal, and corresponding iodide salt were obtained in good yields (Scheme 13). [37] Anion exchange afforded desired NTf 2 salts, which were all liquid at room temperature. This simple and reliable procedure enabled the large scale synthesis of the ionic liquids.…”

“…A mixture of carboxylic acid, benzyl bromide and base efficiently progressed the reaction in 15 a (Figure 5). [37b] During the workup, the acetal‐type ionic liquid 15 a was firstly hydrolyzed, and then the mixture was extracted using CH 2 Cl 2 and ethyl acetate. The CH 2 Cl 2 extract contained the desired ester 17 in 92 % yield, and the ethyl acetate extract afforded diol‐type ionic liquid 14 a in 92 % recovery.…”