Recycling of a homogeneous catalyst using switchable water

Abstract

Aqueous/organic biphasic catalysis allows easy separation of a homogeneous catalyst from product, but is often inefficient when hydrophobic substrates are used. A system based on switchable water is monophasic in the absence of CO₂ and biphasic in its presence. Catalysis can be performed in the monophasic solvent, and then switched to a biphasic system, separating catalyst from product. Removal of CO₂ allows for easy recycling of the catalyst. Hydroformylations have been achieved using this solvent system. The catalyst was recycled several times with minimal loss of activity.