Ionic liquids in transition metal-catalyzed hydroformylation reactions

The latest state of the art in ionic liquid-based hydroformylation is reviewed in detail in this chapter. This multiphase homogenous catalytic system represents a promising strategy in order to reduce catalyst leaching during product separation and achieve the desired ratio of linear-to-branched aldehyde with a high catalytic activity and yield. A series of different catalytic systems, ionic liquids (ILs), and ligands together with their application in the hydroformylation of a variety of alkenes is presented. The features of those ILs derived from their composition and their interactions with substrates and catalysts are also discussed. In addition, recent studies on the catalyst distribution in the bulk and on the surface of ILs are summarized. Herein, the properties of the ligands show an impact in the activity and selectivity of the reaction. Moreover, not only Co and Rh complexes can be applied in the hydroformylation in ILs but also Pt and Ru complexes. On the other hand, the uses of CO₂ as chemical C¹ feedstock or scCO₂ as carrier for the reagents and products in the hydroformylation reaction are commented. Catalytic processes where supported ionic liquid phases (SILPs) and nanocatalysts intervened complement this work.