thrax
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Registered: 25-3-2024
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PerFluro Carbon Purification and Distilation.
Do any of you have experience distilling possibly flammable solvents at high temperatures?
I am a biochemist at a university, and for some of our experiments, we use a PFAS compound to treat our cells.
I am more biology-focused than chemistry-focused, so I need advice on how to proceed with this chemical purification.
Here is some background information:
We used to buy FC-3283 from 3M, but they stopped selling in March 2025. We’ve known about this for years, so we
have a couple of years’ worth of the 3M stuff remaining, and we’ve even found alternative suppliers of the compound.
However, whenever we test alternate supplies’ PFAS on our cells, they cause inflammation, while the 3M PFAS does not.
We know the main ingredient in 3 M’s FC-3283
(>99% perfluorotributylamine), (IUPAC: 1,1,2,2,3,3,4,4,4-Nonafluoro-N,N-bis(nonafluorobutyl)butan-1-amine)
3M used to sell this PFAS for applications ranging from semiconductor washing to transformer dielectric, so they
probably purified it to the highest tolerance and sold it for all the applications at the highest purity. In contrast,
alternate supplies mainly sell it as a refrigerant. We also know that 3M prepares it by electrofluorination of
tributylamine under HF. So, we suspect alternate supplies do not refine it to the same extent, so some fluorination
byproducts, like unsaturated alkyl amines or partially fluorinated species, remain in the mixture. These impurities
act as surfactants or irritants which damage the cells.
Overall, the main contaminants will likely be derivatives of tributylamine and some HF.
My plan:
1. Take samples for NMR
2. Neutralize HF if necessary
3. Distill reagents.
4. Re-test for cell reactivity.
To start, I’ll take some samples to a colleague on campus to do NMR and see if our guess was correct. If our suspicions
are confirmed, I’ll attempt to purify the mixtures.
I don’t think any residual HF needs to be distilled out. Instead, I’ll mix it with a high pH aqueous solution to remove
the HF from the organic perfluorotributylamine phase and neutralize it.
Where I'm really concerned with separating the perfluorotributylamine from tributylamine and its derivatives.
Tributylamine has a boiling point of about 214 °C while perfluorotributylamine has a boiling point of 178 °C, so I guess
all the side products will have intermediate boiling points. So, I think I can save the first fraction at 178 °C.
Where it gets complicated is that the tributylamine has a flash point of 86 °C, so I’ll need to distill it under a vacuum,
or I’ll need to add Argon to displace the atmosphere from the apparatus constantly.
What do you all think? Am I on the right track or is this a stupid way to attempt this purification?
Any advice is greatly appreciated.
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Deathunter88
National Hazard
Posts: 572
Registered: 20-2-2015
Location: Beijing, China
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Sounds fine to me, however you don't need to worry about filling anything with inert gas or anything. It is common practice to distill flammable
solvents in air - the vapors themselves will push oxygen out of the system. Also the flash point doesn't mean the material will spontaneously combust.
Gasoline has a flash point of -40C but we can use it at room temperature in air without it catching fire.
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