Multiphasic liquid

A multiphasic liquid is a mixture consisting of more than two immiscible liquid phases. Biphasic mixtures consisting of two immiscible phases are very common and usually consist of an organic solvent and an aqueous phase ("oil and water").

Multiphasic liquids can be used for selective liquid–liquid extractions or for decorative purposes, e.g. in cosmetics.

While it is possible to get multilayered phases by layering nonpolar and aqueous phases of decreasing densities on top of each other, these phases will not separate after mixing like true multiphasic liquids.

Compositions

The following types of multiphasic liquids exist:

Triphasic systems

Nonpolar solvent / aqueous biphasic mixture
e.g. using hexane, heptane, cyclohexane, or mineral oil as the nonpolar solvent
- Nonpolar solvent / polar solvent / salt / water
  e.g. 100 ml mineral oil, 100 ml isopropanol, 75 ml water, 35 g calcium chloride
- Nonpolar solvent / water-soluble polymer A, water-soluble polymer B, water
  e.g. hexane, polyethylene oxide, dextran, water
- Nonpolar solvent / water-soluble polymer / salt / water
  e.g. hexane, polyethylene oxide, sodium sulfate, water
- Nonpolar solvent A / solvent B / polymer soluble in solvent B and water / water
  e.g. heptane, dichloromethane, polyethylene oxide, water
Nonpolar solvent A / solvent B / polymer soluble in solvent B and water / salt / water
e.g. 16.3% heptane, 21.7% dichloromethane, 9.5% polyethylene oxide, 51.5% water, 0.1% sodium sulfate
Nonpolar solvent / hydrophobic salt / water
e.g. iso-octane, Aliquat 336 (methyltrioctylammonium chloride, a phase transfer catalyst), water [1]
- or: cyclohexane, bmim-PF₆ (an ionic liquid), water [2]
Hydrophobic ionic liquid – water – hydrocarbon systems
- e.g. 1-butyl-3-methylimidazolium hexafluorophosphate – water – cyclohexane

Tetraphasic systems

Nonpolar solvent A / solvent B / polymer soluble in solvent B and water / salt / water
e.g. 10.9% heptane, 15.5% dichloromethane, 7.1% polyethylene oxide, 66.5% sodium sulfate (> 0.1%) in water
Nonpolar solvent / Polar solvent / salt / water / Fluorinated solvent
- e.g. Hexane, isopropanol, brine, perfluoromethylcyclohexane
Non polar solvent / Aprotic polar solvent / Water / Fluorinated solvent
- e.g. Octane, 5-methyl-1,3-dioxolane-4-one, water, perfluorodecaline^[1]

Higher-order multiphasic systems

A system with eight phases is known. In addition to a hydrocarbon and an aqueous phase, it includes a silicone oil, an aniline and a fluorous phase, and molten phosphorus, gallium and mercury.^[2]

References

^ Melchiorre, M. et al. (2023). 1,3-Dioxolane compounds (DOXs) as biobased reaction media. Green Chemistry. https://doi.org/10.1039/D3GC00227F
^ Reichardt, C. (2006). Solvents and Solvent Effects in Organic Chemistry. Wiley-VCH. pp. 9–10. ISBN 3-527-60567-3.

External links

Chem. Commun. 1998, 787 Polymer induced multiphase generation in water/organic solvent mixtures. Strategies towards the design of triphasic and tetraphasic liquid systems (pdf)
US patent application 20050215443 Multiphase aqueous cleansing composition
(Movie) Oil and water separation by molecular dynamics simulation

[1] Melchiorre, M. et al. (2023). 1,3-Dioxolane compounds (DOXs) as biobased reaction media. Green Chemistry. https://doi.org/10.1039/D3GC00227F

[2] Reichardt, C. (2006). Solvents and Solvent Effects in Organic Chemistry. Wiley-VCH. pp. 9–10. ISBN 3-527-60567-3.

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