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Aqueous Biphasic Systems with Ionic Liquids
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2.2. Experimental Section
2.2.1. Materials
The mutual solubilities with water were studied for the following ILs: 1-methyl-3-
propylimidazolium hexafluorophosphate, [C3mim][PF6], 1-butyl-3-methylimidazolium
hexafluorophosphate, [C4mim][PF6], 1-methyl-3-propylpyridinium hexafluorophosphate,
[C3mpy][PF6], 1,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide,
[C1mim][Tf2N], 1,3-diethylimidazolium bis(trifluoromethylsulfonyl)imide,
[C2C2im][Tf2N], and 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide,
[C4C1mim][Tf2N]. The ILs molecular structures are shown in Figure 3.
Figure 3. Chemical structure of the ILs studied: (i) [C3mim][PF6]; (ii) [C3mim][PF6]; (iii)
[C3mpy][PF6]; (iv) [C1mim][Tf2N]; (v) [C2C2im][Tf2N]; (vi) [C4C1mim][Tf2N].
All ILs were acquired at IoLiTec with the exception of [C1mim][Tf2N] that was
synthesized in our lab (cf. Appendix A), and all had mass fraction purities > 99 %. To
reduce the water and volatile compounds content to negligible values, ILs individual
samples were dried under constant stirring at vacuum (0.1 Pa) and moderate temperature
(circa 350 K), for a minimum of 48 h. After this procedure, the purity of each ionic liquid
was further checked by 1 H, 13 C and 19 F NMR (cf. Appendix A).
The water used was double distilled, passed by a reverse osmosis system and further
treated with a MilliQ plus 185 water purification apparatus. It had a resistivity of 18.2
MΩ·cm, a TOC lower than 5 μg·L -1 and it was free of particles greater than 0.22 μm. The
10
N +
N +
N
F 3C
N
O
F
F F
F
P -
N
F
S S
O
O
F
i ii iii
iv
O
CF 3
F
F F
F
P -
F
F
N +
N
N +
N
N
+
N
O
O
N
S S
v
F3C O O
CF3 vi
N +
F
F 3C
O
F F
F
P -
N
S S
O
F
F
O
O
CF 3