ninhydric1
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hydrogen fluoride out of 1,1-difluoroethane
I was browsing my local superstore the other day and came upon a computer duster that claimed to have >99% difluoroethane. I also read up somewhere
in a SM thread that the combustion of difluoroethane yields hydrogen fluoride. So out of curiosity, is it possible collect nearly pure hydrogen
fluoride (as hydrofluoric acid) through the combustion of the difluoroethane? Obviously, I'm not going to try this in my home lab, but what would the
setup be?
[Edited on 8-1-2017 by ninhydric1]
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Assured Fish
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The fluoride carbon bond is generally regarded as the strongest bond in all of chemistry, combined with the fact that fluorine is a stronger oxidizer
than oxygen itself, combustion or burning is just oxidation and thus you could not break the carbon fluoride bond by burning difluoroethane or any
other fluoride carbon bond.
I could be wrong but its unlikely, Could you quote where it stated that combustion of difluoroethane yields HF.
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ninhydric1
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@Assured Fish
It has to be determined on a case-by-case basis, but I absolutely would not use difluoroethane at all for this, as it is flammable and its combustion
yields some very deadly compounds such as HF and fluorophosgene. If you should accidentally ignite it, that could be a disaster.
--zts16
http://www.sciencemadness.org/talk/viewthread.php?tid=71284#...
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unionised
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High temperature reaction with steam should produce HF.
It's also less likely to produce carbonyl fluoride..
It's not obvious what you would make the reaction vessel from.
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ninhydric1
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Possibly PFA (perfluoroalkoxyalkanes). They do sell flasks made of PFA, and it seems to be one of the most resistant plastics.
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clearly_not_atara
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Fluorite (the rock) is preferable since it can be decomposed at room temperature with sulfuric acid and distilled to yield hydrofluoric acid with
nearly no contaminants. Furthermore it is available as an ornamental stone practically everywhere in unlimited quantities. If this is still too
expensive you might be able to find a mine within driving distance and get a large quantity for free.
If any part of this process sounds too difficult you simply have no business making HF. It's dangerous and everything you can make with it is also
dangerous.
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Assured Fish
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Fascinating, never have i felt so intrigued being proven wrong.
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unionised
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Quote: Originally posted by ninhydric1  | | Possibly PFA (perfluoroalkoxyalkanes). They do sell flasks made of PFA, and it seems to be one of the most resistant plastics. |
I said "high temperature", and I meant it.
I'm thinking "red hot" or something like that, to get enough energy to break the C-F bonds.
Anything with C-F bonds is (necessarily) going to fail.
When I saw the start of Clearly_not_Atara's post
"Fluorite (the rock) is preferable since it ..."
I wondered at first if they were suggesting a furnace tube made from fluorite.
I think it might do the job, but I don't think it's very practical.
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ave369
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Another one wants to make HF. Why can't you just use Whink? Whink is the only form of HF that is even remotely practical in an amateur setting.
Smells like ammonia....
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Texium
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Ha, I don't think quoting my post that
is strongly cautioning someone against igniting difluoroethane really helps your case.
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ninhydric1
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Note that this post was meant to think theoretically, and not to actually do it. Please read my original post, as it says that I wasn't going to
actually try it. Please read an OP carefully instead of jumping straight to conclusions.
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ave369
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It is common practice for kewls to ensure everyone that no, they are totally absolutely not making HF, phosgene or something, they are just inquiring
(in reality, they totally intend to try). If they tell everyone that they do intend to try, no one here will help them, so they lie. So it's a warning
just in case.
[Edited on 3-8-2017 by ave369]
Smells like ammonia....
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BromicAcid
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Look into using a spark gap or constant electric discharge or an arc. Those used to be favorites of chemists instead of just a naked flame.
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ninhydric1
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@ave239
Ok. Let me get this straight. Even before I made this post, I knew that you could get HF from the store as Whink rust remover. If I were one of those
kewls, I wouldn't have bothered making this post. Then why did I? I had an idea, and I was curious if it would work, so I decided to run it through
the seasoned members of this forum. And I have never been affiliated, nor do I have the desire to be affiliated with, any synthesis or acquisition of
any chemicals that are related to drugs or chemical weapons. So please have substantial evidence before you jump from assumptions to conclusions.
@BromicAcid Thank you for the info. Through lurking on this forum, I have learned that gases such as ozone can be produced through such methods (a
video by TKOR about Jacob's ladder reminded me of it  ). I will look into the
preparation of hydrogen halides via spark gaps, etc.
[Edited on 8-4-2017 by ninhydric1]
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XeonTheMGPony
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Look up silent arc discharge. as you can make a sealed chamber for reactions.
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CrossxD
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react it with sodium hydroxide and than with conc. sulphuric acid.... i think 
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Rhodanide
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I've found that Glass etchant works great for most of the purposes where HF is required. (Mine is Ammonium Bifluoride and HF in H2O.) [It's probably
got other crap in there, but I digress]
You could probably get HF or AMBF from etchant cream, too.
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chornedsnorkack
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| Quote: Originally posted by Assured Fish | The fluoride carbon bond is generally regarded as the strongest bond in all of chemistry, combined with the fact that fluorine is a stronger oxidizer
than oxygen itself, combustion or burning is just oxidation and thus you could not break the carbon fluoride bond by burning difluoroethane or any
other fluoride carbon bond.
I could be wrong but its unlikely, Could you quote where it stated that combustion of difluoroethane yields HF. |
C-F bond is stronger than C-O, but H-F is also stronger than H-O bond. The reaction
COF2+H2O->CO2+2HF
goes to right, spontaneously and violently.
So even if the initial reaction were
2C2H4F2+5O2->2CO2+4H2O+2COF2
the end result would still be
2C2H4F2+5O2->4CO2+2H2O+4HF
Now as for materials of reaction vessels, standard materials to handle F2and HF are metals which passivate well - Cu and Ni. Which are heat
resistant and common. Because of softness and good heat conductivity of Cu, Cu tubes and tools of working them are common.
If you want to burn fluorocarbon compounds and prevent escape of any noxious fumes, you´d want to ensure that combustion goes to completion, to
CO2 and HF, and then condense/scrub out the HF vapours. How would you set up a condenser to safely capture HF vapours and recover them as
(dilute) hydrofluoric acid?
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