Extending the range of switchable-hydrophilicity solvents

Area of Science:

• Green Chemistry
• Solvent Engineering

Background:

• Switchable-hydrophilicity solvents (SHSs) exhibit tunable miscibility with water.
• Previously reported amine SHSs were limited to specific basicity (9.5 < pKaH < 11) and hydrophilicity (1.0 < log Kow < 2.5) ranges.

Purpose of the Study:

• To extend the functional range of amine-based SHSs.
• To explore the influence of process parameters on SHS performance.

Main Methods:

• Investigating the effect of varying carbon dioxide (CO2) pressure.
• Modifying the water-to-SHS volume ratio during the switching process.

Main Results:

• Successfully enabled amines with lower basicity (pKaH < 9.5) to function as SHSs.
• Facilitated the use of amines with higher hydrophilicity (log Kow > 2.5) as SHSs.
• Demonstrated that increased CO2 pressure and/or water ratio expands SHS applicability.

Conclusions:

• The operational range of amine-based SHSs has been significantly broadened.
• Process parameter control offers a versatile strategy for utilizing a wider array of SHSs.
• This work expands the toolkit for designing and applying switchable solvents in various chemical processes.