Immobilized ionic liquids on Fe3O4 nanoparticles: A potential catalyst for organic synthesis

Ionic liquids (ILs) are getting prominence as eco-sustainable solvents, especially as alternatives to existing me-diums in chemical reactions because of the advantage of incredibly low vapor pressure, which makes them simple to preserve in a process. Although there are multiple advantages to adopting ILs, still some restrictions place a cap on their usefulness due to which ILs are supported or immobilized on solid support materials which combine the benefits of ILs (low volatility, high solvent capacity, etc.) with heterogeneous support materials. Magnetic nanoparticle-supported catalytic systems have received much attention due to their extraordinary qualities like ease of availability, large surface-to-volume ratio, chemical inertness, and outstanding thermal stability for the immobilization of ILs. However, due to iron cations in two valence states, Fe2+ and Fe3+, magnetite Fe3O4 has the most remarkable characteristics in the inverse spinel structure thus, Fe3O4 MNPs have attracted great importance as solid supports for ILs. However, metal nanoparticles accumulate into massive particles and losses the active reaction sites, promoting deactivation, thus coating of nanoparticles are required to prevent irreversible aggregation, for this all Fe3O4 nanoparticles are coated with a homogenous silica layer providing various benefits, such as relatively good media stability and ease of surface functionalization. This review summarizes the applications of immobilized ILs on Fe3O4 MNPs in organic synthesis. Enhanced efficiency can be achieved by mixing desired ionic liquid and nanoparticle into a hybrid nanostructure.