1-Butyl-3-methylimidazolium hexafluorophosphate explained

1-Butyl-3-methylimidazolium hexafluorophosphate, also known as BMIM-PF₆, is a viscous, colourless, hydrophobic and non-water-soluble ionic liquid with a melting point^[1] of -8 °C. Together with 1-butyl-3-methylimidazolium tetrafluoroborate, BMIM-BF₄, it is one of the most widely studied ionic liquids. It is known to very slowly decompose in the presence of water.^[2]

Preparation

BMIM-PF₆ is commercially available. It may be obtained in two steps: BMIM-Cl is synthesized by alkylating 1-methylimidazole with 1-chlorobutane. A metathesis reaction with potassium hexafluorophosphate gives the desired compound; the tetrafluoroborate may be prepared by analogously using potassium tetrafluoroborate.

See also

• 1-Butyl-3-methylimidazolium tetrachloroferrate

Further reading

• S. Carda-Broch . A. Berthod . D.W. Armstrong . Solvent properties of the 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid . . 375 . 2 . 191–199 . 10.1007/s00216-002-1684-1 . 12560962 . 2003. 32506513 .

Notes and References

1. Book: Ionic Liquids in Chemical Analysis. xxvii. Mihkel Koel. CRC Press. 2008. 978-1-4200-4646-5.
2. R.P. Swatloski . J.D. Holbrey . R.D. Rogers. amp . Ionic liquids are not always green: hydrolysis of 1-butyl-3-methylimidazolium hexafluorophosphate . Green Chem.. 2003 . 5 . 361–363 . 10.1039/b304400a . 4.