1-Butyl-3-methylimidazolium hexafluorophosphate

1.92 mS/cm

Clear pale yellow oil

1-Butyl-3-methylimidazolium hexafluorophosphate is an ionic liquid employed in many environmentally friendly reactions.

It can also be used as a medium for reactions such as:

• Ring-closing metathesis of diene and enyne substrates in the presence of a novel recyclable ruthenium carbene complex.
• Nickel(II)acetylacetonate catalyzed oxidation of aromatic aldehydes to the corresponding acids using dioxygen as the oxidant.
• Lipase-catalyzed enantioselective acylation of allylic alcohols.
• Allylation of aldehydes using tetraallylstannane to yield homoallylic alcohols.

those consisting of tetrafluoroborate, alkylsulfate, alkylsulfonate, carboxylate, or phosphate anions are hydrophilic and are completely dissolved in water. Dupont and coworkers first reported stable hydrophobic imidazolium salt, 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) in 1996. Since then, this salt has been used as a typical hydrophobic IL in many chemical reactions because its mixture with water forms a biphasic layer. Furthermore, this IL shows poor solubility in hexane or ether, which allows realization of an easy work-up process. However, [C4mim][PF6] was reported to be sensitive to the moisture at high temperature and produced hazardous hydrogen fluoride as it decomposed. Therefore, bis(trifluoromethanesulfonyl)amide (NTf2) salts are now recommended as the anion for preparing hydrophobic ILs.

1-Butyl-3-methylimidazolium hexafluorophosphate is an imidazolium-based, hydrophobic, room temperature ionic liquid (RTIL). It can be prepared by reacting 1-methylimidazole with chlorobutane. Gaseous hydrofluorocarbons (HFCs) such as fluoromethane, fluoroethane and 1,1,2,2-tetrafluoroethane are soluble in BMIMPF₆.