Perfluorohexane (It hates everything!)

Everyone knows that many organic solvents won't mix with water (or, more generally, some polar solvents won't mix with some nonpolar solvents). What you might not know is that some highly fluorinated liquids aren't very polar at all, but they won't dissolve in water or many organics.


In fact, you can mix certain organic solvents, the fluorous stuff, and water, and end up with three phases! The company in that link has made a business of using perfluorinated tags to stick on your molecule, which in turn stick to a perfluorinated solid support (you later wash off your stuff with something that gets along with the fluorous tag).

3M sells a mixture of fluorinated light hydrocarbons known as "fluorinert" that include molecules such as the above. The bizzareness of fluorine defines these compounds - not only are their solubility characteristics unique, they are really stable thanks to a strong carbon-fluorine bond, making them one of those rare small alkyl halides that aren't toxic - it's even possible to breathe them!


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"What you might not know is that some highly fluorinated liquids aren't very polar at all, but they won't dissolve in water or many organics."

If something is non-polar it is EXPECTED not to dissolve with water. This is a very basic chemical concept and it troubles me that you run a chemistry blog without a basic understanding of solubility.

Cool demo of 4 layers: Sudan III in ethyl acetate is red (top), nickel (II) chloride in water (green), perfluorohexane (colorless), mercury (silver, bottom layer). All four layers are immiscible. Put them in a vial, shake it up and voila, four layers.

In preparing this demo I found that over time hexane and perfluorohexane will mix to a very significant extent but ethyl acetate will not.

By Bunsen Honeydew (not verified) on 22 Jan 2008 #permalink

Molecular biology often makes reference to hydrophobic/hydrophyllic interactions, but, as I have seen demonstrations of multiple mutually-immiscable layers before, I have often wondered if there are other phobic/phyllic interactions in nature.

It isn't much of a stretch to imagine domains of a biological molecule mimicking the perfluoro interactions that you have demonstrated.

By Paddywhacker (not verified) on 22 Jan 2008 #permalink


The unique properties of perfluoro domains have been used in the enrichment of various molecular subsets, i.e. cysteinly peptides, phosphopeptides, amino acids, etc, from complex biological mixtures. The molecules can be tagged with a perfluoro chain, then separated from non-tagged components using a perfluoro modified silica. The seminal paper is Brittain et al, Nat. Biotech. 2005, 23(4), 463.

For all others interested in this area of chemistry and biology, known as fluorous, you can visit the Fluorous Technologies, Inc. website ( where there is a wealth of information.

One of the things you'll also find is F-blog, which is a blog dedicated to all things fluorous. We try to put about 2-3 new posts/week, so you can visit that also.

Disclaimer: I am an employee of Fluorous Technologies, Inc.

Mmmmmm Teflon-ish.

By Vince Noir (not verified) on 23 Jan 2008 #permalink

3 phases?! Is that all you got?!?!? Dig up a copy of Hildebrand and Scott and look at the overleaf page: 10 (that's ten, not a binary 2) fluid layers in 1 test tube.

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