The subtle but substantial distinction between ammonium- and phosphonium-based deep eutectic solvents

摘要

In the search for greener solvents to replace the commercially organic volatile solvents that caused negative impact on both human beings and the environment, researchers investigated a number of potential alternatives, e.g. ionic liquids (ILs), supercritical CO2, deep eutectic solvents (DESs), etc. DESs are mixtures of two or more compounds that due to interaction forces have melting points less than that of any of their constituents. With the wise selection of their constituents, DESs can have attractive physiochemical properties, e.g. low volatility, high thermal stability, moderate electrical conductivity, extremely low toxicity, and biodegradability. In addition, the DESs' properties could be tuned by selecting constituents with suitable chemical structures and by changing the molar ratio of the constituents.