Recycling of a homogeneous catalyst using switchable water

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.