Melting points

Ionic liquids:

Polarity (adjustable) Very low vapor pressureLiquid ranges (> 300 °C)Solubility of gases & a wide range of compoundsImmiscibility with solventsHydrophilicity/lipophilicity (adjustable)Acidity (adjustable)

Charge distribution for [C4mim][PF6]. (4-1-PF6)

Red corresponds to regions of high relative negative charge, and blue to high relative positive charge.

New ionic liquid made up of a cobalt-carbonyl anion and imidazolium cation. The liquid is catalytically active in its own right.

Ionic liquids can form structures in their own right such as a stable smectic liquid crystal eg. [C14mim][PF6].

Ionic liquids made of dialkylimidazolium cations and appropriate anions are useful alternative media of special properties to be employed.

Scheme 1. Friedel-Crafts acetylation reaction of naphthalene.

O

O O Cl

C6H5NO2 EMImAl2Cl7

O Cl

1-isomer2-isomer

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The phase preference of the three forms of thymol blue in [bmim][PF6].

Utilizing recyclable gases to activate the proton switch: (a) Thymol blue in the upper aqueous phase at pH = 13; (b) Bubbling CO2 through the RTIL/aqueous system, note the change in dye color; (c) The yellow form of thymol blue in the RTIL phase; (d) Bubbling NH3 through the RTIL/aqueous system, note the darker color of the dye; (e) The blue form of thymol blue settling into the top aqueous phase.

Solid/liquid separations utilizing the low melting [dmim][PF6]: (a) An acidic thymol blue solution residing over solid [dmim][PF6] prior to melting; (b) After melting the salt, thymol blue partitioned to the [dmim][PF6]; (c) Recrystallization of [dmim][PF6] leaves behind a red residue; (d) An alkaline wash is added to remove the dye from the solid surfaces; (e) The colorless crystalline [dmim][PF6] solid after washing.

a b c d e

Figure 1 | A class apart. Ionic liquids show a range of properties. Here, hydrophobic EMIm NTf2 (bottom phase) is separated from hydrophobic C9H20 by blue-dyed H2O. Involatility was assumed to be a characteristic common to all members of the class, until Earle showed otherwise.

FIGURE 1. Labelled photograph of the Kugelrohr oven and distillation apparatus.

FIGURE 2. Schematic representation of the differences between protic and aprotic ionic liquids, in both the liquid and the gaseous phases.