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.