Effective extraction of quinine and gramine from water by hydrophobic ionic liquids: The role of anion

In this work, a series of hydrophobic ionic liquids (ILs) with ClO 4 − , BF 4 − , PF 6 − , CF 3 SO 3 − and bis(trifluoromethanesulphonyl)imide (NTf 2 − ) as anions were synthesized. Their extraction ability for the two alkaloids, quinine and gramine was studied. The experimental results suggested that the extraction ability of ILs had no clear relationship with the alkyl chain length on the IL cation but depended on the hydrophobicity and hydrogen-bonding strength of the IL anion. The CF 3 SO 3 − -based ILs were stable against hydrolysis and exhibited better extraction ability for the two alkaloids. Thermodynamic analysis suggested that the extraction of the two alkaloids was an entropy-driven process. These results indicate that CF 3 SO 3 − -based ILs are ideal solvents for recovering alkaloids from the water phase.