Enhancing the Efficiency of Switching Switchable Hydrophilicity Solvents Using Continuous Flow Approaches

CO₂-switchable hydrophilicity solvents, hydrophobic amines which reversibly react with water and CO₂ to form water miscible solvents, are promising nonvolatile alternatives to conventional organic solvents while offering improved solute separation compared to neoteric solvents such as ionic liquids and deep eutectic solvents. A significant limitation of switchable hydrophilicity solvents is the slow rate of the switching process, which can lead to evaporative losses even of the nonvolatile solvent used as well as incurring a significant energy cost. The lengthy switching procedure can also affect the purity of compounds that possess poor thermal stability. This article details the use of a vortex fluidic device in both batch and continuous flow modes to enhance the efficiency of reactions between the amine switchable hydrophilicity solvent, water, and CO₂, substantially reducing the required reaction time. The ability of the vortex fluidic device to enable the reverse switching process is tested and discussed, along with the implementation of a continuous flow methodology capable of substantially reducing switching times. These results highlight the potential of this strategy to increase the throughput of CO₂-switchable hydrophilicity solvent transformations in both directions, with the potential to scale this approach discussed.