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Author: Subject: K2MnO4 conversion to KMnO4
JoeChemist
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[*] posted on 14-8-2009 at 07:13
K2MnO4 conversion to KMnO4


Hey how are you all doing, I´m trying to convert K2MnO4 into KMnO4.... i´ve been able to achieve this through liquid oxidation, but out of 1 Kilo my result is about 270 Kg (27%), any ideas on how i can raise the result %?


Edit by chemoleo: title error

[Edited on 15-8-2009 by chemoleo]
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Joauml
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[*] posted on 14-8-2009 at 09:15


well, Im not sure if I understood what you are trying to do( I don't speak english very well), but, what exactly was the metod that you have used to oxidate the K2MnO4?
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Picric-A
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[*] posted on 14-8-2009 at 12:49


Please give us more information on what you have done... what have you used to oxidise it ect...
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kclo4
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[*] posted on 14-8-2009 at 14:16


Perhaps you can add an acid of some sort?

K2MnO4 + HX = KMNO4 + KX

I also found this:
KMnO4 + KI → K2MnO4 + ½ I2




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Jor
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[*] posted on 14-8-2009 at 14:27


Just acidify a conc. solution of K2MnO4 with sulfuric acid, and filter the formed MnO2. Because KMnO4 not very soluble, there´s probably also some KMnO4 crystals mixed in the MnO2.
I´m not sure if boiling down the KMnO4/solution (in H2SO4) will decompose some permanganate, but I would say boil down, cool, and filter.

I have no experience with the above --> I buy my KMnO4.
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DJF90
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[*] posted on 14-8-2009 at 16:10


I'm not sure if this guy is trying to oxidise manganate (VI) or reduce manganate (VII). I'm going to guess the latter, as KMnO4 is much easier to obtain than K2MnO4, and due to this line:
Quote:

I´m trying to convert K2MnO4 into KMnO4....

I'm sure I saw this preparation in inorganic syntheses somewhere...
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Jor
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[*] posted on 14-8-2009 at 16:14


Well, when one wants to make KMnO4, the synthesis goes via K2MnO4.

This is because MnO2 is oxidised to K2MnO4 by heating in a crucible with KOH and KClO3 (or possibly KNO3).

So although K2MnO4 may be harder to buy, it is something wich needs to be made before KMnO4 can be synthesised.
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DJF90
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[*] posted on 14-8-2009 at 16:19


Yes I remember now. Until he says what method he's trying its hard to suggest improvements :/
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entropy51
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[*] posted on 14-8-2009 at 16:25


Both electrolysis and chlorination have been used for oxidation of manganate to permanganate, as in this patent and others:

http://www.google.com/patents/about?id=I9BOAAAAEBAJ&dq=1...

but where I live KMnO4 can be purchased cheaply in bulk at Sears, Home Depot, etc. etc. Says "Potassium Permanganate" right on the label. No muss, no fuss.

[Edited on 15-8-2009 by entropy51]
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TIETSE
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[*] posted on 14-8-2009 at 21:23


hey use chlorine gas , you got a supersaturated solution of K2MnO4 and you put the gas in there , in few minutes all the green turns in violet
To form chlorine do the next reaction:
2 NaCl + 2 H2SO4 + MnO2 → Na2SO4 + MnSO4 + 2 H2O + Cl2




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kclo4
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[*] posted on 14-8-2009 at 22:22


Please explain the reaction where potassium manganate is turned into potassium permanganate with Cl2 please. What does it form, KCl or hypochlorites?







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Taoiseach
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[*] posted on 15-8-2009 at 02:19


In his exact words he has multiplicated 1 kilogram of K2MnO4 into 270 kilograms. Altough this sounds like an achievement of almost biblical scale my guess is that this is not what he really did.

If its about oxidation of K2MnO4 you have numerous options. CO2 would be the easiest:

3 K2MnO4 + 2 CO2 + H2O -------> 2 KMnO4 + MnO2 x H2O + 2 K2CO3

This is a simple disproportionation thus yields will never exceed about 60%. The remaining K2MnO4 precipates as hydrated MnO2.

Electrolytical oxidation or chlorine would allow for higher yields.

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blogfast25
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[*] posted on 19-8-2009 at 08:07


JoeChemist: anything you might possibly want to know about manganate and permanganate is here, obviously:

http://www.sciencemadness.org/talk/viewthread.php?tid=8480
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