Alexein
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How to make Hexafluorobutyne?
Hey all.
Anyone got any ideas how to make hexafluorobut-2-yne?
CF3CCCF3 or think of butane with three fluorines on each of the end carbons and a triple bond on the middle two carbons.
So far i've been thinking of dehalogenating 2,3-dichloro hexafluorobut-2-ene by zinc in acetic anhydride. however i wanna stay away from that reaction
for now because 2,3-dichloro hexafluotobut-2-ene is as toxic as nerve gas.
anyone got some ideas?
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solo
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This may help.....solo
Synthesis of Organoflourine Compounds
http://tinyurl.com/2l6j37
[Edited on 14-7-2007 by solo]
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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Alexein
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A very interesting reaction.
It appears that all i need to do is obtain KF and hexachloro-1,3-butadiene dissolve them both into some perfluorinated solvent add heat and
hexafluorobutyne is produced.
Sounds almost too easy 
Thanks alot Solo, i'll do so some more research on it but it sounds like it could work.
P.S: Can anyone suggest a cheap perfluorinated solvent?
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Nicodem
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| Quote: | Originally posted by Alexein
So far i've been thinking of dehalogenating 2,3-dichloro hexafluorobut-2-ene by zinc in acetic anhydride. however i wanna stay away from that reaction
for now because 2,3-dichloro hexafluotobut-2-ene is as toxic as nerve gas. |
Excuse me, but your reasoning makes little sense. Firstly because the product hexafluoro-2-butyne is also similarly toxic but given that it is a gas
it is also more dangerous to deal with than the liquid and volatile cis-2,3-dichloro-hexafluorobut-2-ene. Since they are both commercially available,
if concerned about safety, one would be more reasonable to simply buy hexafluoro-2-butyne even if it is almost five times more expensive than
2,3-dichloro-hexafluorobut-2-ene. In my opinion, a four to five times difference in prices is quite reasonable given the work, yields and risks
involved.
Anyway, there are several methods of preparation in the literature but none is particularly more convenient that what you proposed.
But what I was really curios about is where you got the info that "2,3-dichloro hexafluotobut-2-ene is as toxic as nerve gas"? That simply can not be
true or else the big chemical corporations (you know which ones, no publicity here) would not be freely selling it, if a couple of micrograms were
enough to kill humans. And furthermore they would certainly not sell something as toxic in 50 g ampoules as they do. Its MSDS gives a LC50 at 54 ppm
by inhalation for monkeys, which is only a couple of times more than the usual hydrogen cyanide. Such toxicity is quite low when compared to the
dreaded nerve gases. But why would one be so terribly concerned about this starting material when the MSDS gives a similarly scary toxicity for the
gaseous hexafluoro-2-butyne (81 ppm for rats), the product that he wants to prepare? Not to mention that both compounds are quite surely carcinogenic
being small hydrophobic alkylators.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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Alexein
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I'm sorry man, its just a hyperbole. I didn't think the forum had a policy against use of hyperbole.
I hope you're not angry with me. I honestly didn't think that using that phrase would cause such a backlash.
I'm just trying research as many alternatives as i can.
If i can't find alternatives then i will go with original route.
The reason why i'm trying to make it is because i can't buy it where i am. Its not available in my country. So i'm trying to find preps that can be
done using locally available materials.
For what its worth i'm really sorry. I won't use hyperbole in my posts from now on.
I really hope this incident doesn't alienate me from the forum.
what can i do to make it up to you?
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