Ionic Liquids

Imagine a smart solvent that can be switched reversibly from a liquid with one set of properties to another that has very different properties, upon command. Here we create such a system, in which a non-ionic liquid (an alcohol and an amine base) converts to an ionic liquid (a salt in liquid form) upon exposure to an atmosphere of carbon dioxide, and then reverts back to its non-ionic form when exposed to nitrogen or argon gas. Such switchable solvents should facilitate organic syntheses and separations by eliminating the need to remove and replace solvents after each reaction step.

The effects of substituents at the alpha-carbon atom on the donor properties of primary amines and amino alcohols have been studied. Such substituted amino species have important applications in industrially relevant gas separation processes. Qualitative molecular orbital arguments, along with detailed calculations at the MNDO level of theory, show that upon methyl substitution at the alpha-carbon atom the interaction of the methyl group properties of the amino species. Infrared spectroscopic data supporting the calculations are also described.

The basicity of several basic ionic liquids is studied quantitatively for the first time, and the basicity of the ionic liquids can be switched repeatedly by bubbling CO2 and N2 through the solution alternately.