vulture
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Preparation of perchlorates
I was thinking of several methods to prepare perchlorates from chlorates.
As permanganate is a stronger oxidizer, I figured out this hypothetical reaction:
3KClO3 + 2KMnO4 + 2HCl ->
3KClO4 + 2MnO2 + H2O + 2KCl
Now, obviously, there are a lot of unwanted byproducts.
Now someone suggested using HMnO4 instead of KMnO4.
Preparation of HMnO4:
2KMnO4 + H2SO4 -> Mn2O7 + K2SO4 + H2O
Mn2O7 + H2O -> 2HMnO4
The problem here is the separation of K2SO4 from the solution.
KClO3 + HMnO4 -> KClO4 + H2O + MnO2
would then be the final reaction.
Wouter Visser describes a method with persulfate but it seems to produce bad yields, so does the electrolysis.
Any thoughts?
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madscientist
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It doesn't seem right that MnO2 is formed as a product; I'm not sure though, it's possible. Do you have any chemistry books that speak of a reaction
that reduces KMnO4 to MnO2 (and other compounds, obviously)?
Preparing HMnO4 seems to be a broad enough subject to deserve a thread of its own. I'll start one on that topic soon; I have successfully prepared
HMnO4 via several different methods before, and am somewhat familiar with its properties.  For now, there is a little information on it in the "Ammonium permanganate preparation" thread in the Energetic Materials section.
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Polverone
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KClO3 and (even more) KClO4 are not very water soluble. HCl will be oxidized by KMnO4 to release chlorine gas. I would be rather surprised if the
first reaction happened as you wish. An old preparation for KMnO4 was to intimately mix and fuse MnO2 and KClO3 at red heat (taken from Muspratt). It
is possible that some KClO4 is formed during this process, but probably not to a large degree, since this method apparently gave relatively good
yields.
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vulture
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Most cold oxidation reactions with KMnO4 yield MnO2. What could it be else in that reaction, it's been written according to redox theory.
Polverone might be right about the HCl getting oxidized. Hmm, then I would have to use H3PO4, as H2SO4 will cause Mn2O7 formation. While I'm thinking
about it, would that be a bad thing or a good thing? Reaction heat could cause an explosion though.
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Polverone
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You can certainly try H3PO4. After all, would research be any fun if you knew the outcome before hand? H2SO4 would react with both the KMnO4 and the
KClO3. You don't want to use it.
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vulture
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Okay, i've been investigating something more in persulfate oxidation, because I recently acquired some ammoniumpersulfate (which is cheap as dirt).
Wouter Visser describes a process where he boils KClO3 in solution with a persulfate. I think the reaction has to be like this:
KClO3 + (NH4)2S2O8 ->
KClO4 + (NH4)2S2O7
There are a few problems however:
1. The reaction is slow and thus timeconsuming
2.Hazard of ammoniumchlorate formation (although ammoniumchlorate doesn't seem to be as unstable as some claim)
3. How soluble is ammoniumdisulfate?
The reaction would pose not as much problems if one used potassium persulfate, however, there is the question of solubility again.
Also, there is a really MADscience way to produce perchlorate:
3KClO3 + 3H2SO4 -> KHSO4 + HClO4 + 2ClO2 + H2O
Now, according to me, the perchloric acid will react with the KHSO4 to form H2SO4 and KClO4.
(Kb HSO4 - = 10^-18 Ka HClO4 = 4x10^8, resulting in K= 4000)
Now would there be a way to convert the ClO2 to ClO4 -?
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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vulture
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A few corrections
Odd, the equation above with KClO4 and H2SO4 seems to go the other way round.
Anyway, the KMnO4 oxidation experiment has failed so far, even when heated.
I know there's something I'm overlooking here but I don't know what.
I'm going to try dichromate oxidation if I have the time and I have decided to use H2SO4 in the following experiments as the reactants are all dilute.
When brainstorming about KClO4, some really madscience reaction occured to me!
I thought about reacting KClO3 with F2! If you're lucky (and if it won't kill you) you'll end up with KClO4, KF and ClO2 which can be used to prepare
chlorites.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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madscientist
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You may already be aware of this, but it is suicidal to mix concentrated sulfuric acid with a chlorate. The reaction is explosive.
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vulture
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Well, the reaction seems to be explosive when done in larger quantities. It's mainly explosive because the ClO2 decomposes of reaction heat.
Brainfever had an accident with this, but that was because some H2SO4 splattered into a jar filled with AP, IIRC.
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PHILOU Zrealone
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Actually it was H2SO4 (conc) that inflamed some KClO3 that expelled burning/exploding pieces onto drying CTAP that detonated!
KMnO4 and MnO2 are used to free smoothly O2 from KClO3 upon heat!
Better heat KClO3 at the desired T to get KClO4!
4KClO3 -heat-> 3KClO4 + KCl
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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vulture
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I tried the heating method, but unfortunately I only have metal containers to do this, which decompose the chlorate entirely.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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Theoretic
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I think that perchlorates could be prepared by disproportionating chlorates with heat. Example:
4NaClO3->3NaClO4 + NaCl
----------------------------------------------
This has been said a FEW lines above your post. Please read topics before posting!
[Edited on 30-6-2003 by vulture]
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