Nonaqueous Microencapsulation of Ionic Liquids and Deep Eutectic Solvents: Heterogeneous Organocatalysts for Michael Addition Reaction

This research expands the application of the oil in oil (O/O) emulsion/nonaqueous sol–gel technique for the microencapsulation of ionic liquids (ILs) and proline-based deep eutectic solvents (DESs). The confinement of ILs and DESs within silica microcapsules produced easily handleable powders that could be effortlessly dispersed in different solvents and separated by simple centrifugation. Hence, eliminating the drawbacks caused by the high viscosity of bulk ILs and DESs. In addition, among the microencapsulated ILs and DESs, two proline-based compounds were successfully used as heterogeneous organocatalysts in the Michael addition of thiols to α,β-unsaturated ketones. The capsules were separated from the reaction mixtures and recycled several times without any drop in conversion.