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Author: Subject: Oxidisation of KI with Hydrogen Peroxide
raiden
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[*] posted on 21-3-2008 at 02:18
Oxidisation of KI with Hydrogen Peroxide


@ The Moderator: I meant to post this in Reagent Acquisition but used the wrong tab! Sorry!


Hey all.

I remember reading on here somewhere (I think) that one is able to oxidise Potassium Iodide with Hydrogen Peroxide and obtain elemental Iodine. I have searched and searched and cannot find any information!

Basically I have these chemicals:
HCl
KI
MnO2
H2O2
KMnO4

I have tried a method using HCl and KMnO4, which, because the oxidiser was used in excess, oxidised the HCl as well, thus gassing me.

I do not have access to Sulfuric acid for a while due to finances to perform the proper Frogfot synth using it instead of HCl. What should I do?

Thanks.

[Edited on 21-3-2008 by raiden]
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[*] posted on 21-3-2008 at 03:33


Dissolve some of your KI in diluted HCl and slowly drip in H2O2 while stirring. The iodine precipitates right out, and HCl and H2O2 don't make chlorine in dilute aqueous solution.

You need to use at least the same molar amount of HCl than KI, and H2O2 is added until the solution above the iodine precipitate is clear.

2 HCl + 2 KI + H2O2 ---> I2 + 2 KCl + 2H2O




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[*] posted on 21-3-2008 at 07:27


I like to add HCl to NaOCl and bubble the chlorine gas that is generated into a KI solution. This method has worked suprisingly well for me.

Here is a link of how I did it with pictures.
http://www.dererumomnis.org/bbs/index.php?topic=293.0




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[*] posted on 21-3-2008 at 08:06


Yes, that works, but you have to get the amount of chlorine exactly right- too little, and some of your iodine stays in solution as potassium triiodide (deep brown solution), too much and the iodine will be contaminated by iodine chlorides.

The H2O2 method is better because an excess of H2O2 is not going to hurt the yield or product in any way.
3% H2O2 is suitable as well, too.




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[*] posted on 21-3-2008 at 16:07


Okay, I am thinking of using 1 molar solutions of KI and HCl - is this suitable?
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[*] posted on 21-3-2008 at 16:10


Yes, thats suitable. Use HCl in a bit of excess, you really don't want to have a mix of KI and H2O2 under neutral conditions (KI strongly catalyzes H2O2 decomposition, but when there is enough acid only iodine is produced).



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[*] posted on 21-3-2008 at 21:05


Alrighty, I did the synth

6 grams of 37% HCl was added to 70ml of water
8 grams of KI was then dissolved in this liquid

I then added the 6% H2O2 slowly, waiting for the solution to clear, it didn't after about 15ml (is it supposed to take more?).

Crystals were filtered, dried and then resublimed onto a round bottomed flask containing ice cold water.

Yield was between 1 and 2 grams (crap scales). No where near the theoretical (6.3).

Is this method just bad or should I have added more H2O2?

Thanks guys.

By the way, is I about to be stored in normal zip lock bags or will it attack it?

[Edited on 21-3-2008 by raiden]
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[*] posted on 21-3-2008 at 21:12


No! Do not store it in a ziplock bag. I2 will diffuse through most plastics including thin PTFE.

IMO, yes you should use more H2O2. Did your solution ever turn completely clear? If so, what is your I2 source? Is it reagent grade pellets/powder? Many people tend to think that the "iodine pills" are pure KI, they are absolutely not.

If you are using pure KI (and you're sure of the purity) and more H2O2 doesn't work (35% is preferred), try using H2SO4, even dilute H2SO4 should work. It's easy to find and cheaper than HCl. Go get some.




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[*] posted on 21-3-2008 at 22:21


You didn't do what I said- you should have added H2O2 until the solution turned clear above the precipitate. No wonder your yield was bad.
I hope you saved the filtrate, the rest of your iodine is in there, just add more H2O2!




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[*] posted on 22-3-2008 at 05:44


You no not even have to drip in the H2O2. Just take excess acid (how much excess does not matter, as long as it is in excess) and then add excess H2O2 (again, how much excess is not important, better take way too much than some too little).
When you do this, and you put it away, then after an hour (at most) you'll have a nice layer of dark grey solid iodine and a clear light brown liquid above it. The light brown liquid only contains a very little amount of iodine, that loss can be neglected.

If you have too little acid or too little H2O2, then yield will be crap, be sure to use excess of both!




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[*] posted on 25-3-2008 at 10:31


A solution of two parts KI in grams to five parts H20 in ml and three parts HCl in ml is stirred until the KI is dissolved. 3% H2O2 is dripped into this solution with stirring until the solution clears. The iodine will fall in long crystals 5-12mm in length.

An alternative method is to add to the above KI-HCl solution eight parts of NaOCl in ml rather than the peroxide. The solution is stirred after adding the NaOCl, then allowed to sit for five minutes. It is advisable to cover the container during this time, but sealing is not necessary. After five minutes dilute with fifteen parts of water. Collect the iodine by filtering, and rinse well with water. If the filtrate is still dark brownish in color, drip 3% H2O2 into it until the color clears, then allow to stand for approximately an hour. The remaining iodine in the filtrate will collect as grayish crystals at the bottom of the container.

The NaOCl method is the faster of the two; the H2O2 method seems to give slightly purer iodine judged by the residue remaining after subliming the iodine. Dry the iodine well before subliming it.




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[*] posted on 25-3-2008 at 12:55


I wouldn't use bleach for this as it would just add contaminates. Like woelen said, exact measurements are not necessary and more is better than less. Basically, it's difficult to use too much.

Also, my iodine never formed "long crystals" from this method. Strange. Could you post a picture of your crystals geezmeister? That would be an excellent. I will post one once I recieve some more KI (on it's way!) along with a simple write up.

Also, does anyone know of a solvent, in which I2 is completely insoluble, that could be used to wash it to avoid losses?

Geezmeister, why is it that you seem to only be interested in reagents and "syntheses" related to amphetamine production? Are you interested in anything else at all (non-drug)?




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[*] posted on 25-3-2008 at 15:53


I2 from KI http://www.frogfot.com/synthesis/iodine.html



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[*] posted on 25-3-2008 at 19:40


I wouldn't waste potassium permanganate or dichromate on this especially since H2SO4 and H2O2 gives just as high if not higher yields. And both of those leave insoluble contaminates.

I suppose if you have a cheap source of permanganate and you are already going to resublime this is a better method as it doesn't require as much water.

But from my experience, permanganates are not OTC (in the US) and expensive to obtain online (sometimes requiring HAZMAT fees).

[Edited on 25-3-2008 by MagicJigPipe]




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[*] posted on 28-3-2008 at 15:42


Quote:
Originally posted by MagicJigPipe
I suppose if you have a cheap source of permanganate and you are already going to resublime this is a better method as it doesn't require as much water.

But from my experience, permanganates are not OTC (in the US) and expensive to obtain online (sometimes requiring HAZMAT fees).


Get it while you can, folks:

http://www.lowes.com/lowes/lkn?action=productDetail&prod...

I found that only one of the four stores in my area carried it, but that store sold it to me with no questions asked. (I don't know if it was out on display -- I asked about it at the service desk, and they had someone bring a bottle of it up to the front.)

I don't know about its purity, but it certainly behaves like the reagent KMnO4 I had previously, at least with glycerine and with H2SO4. (Mix a fraction of a gram with a few drops of H2SO4, hit it with a stick, get a loud pop and brown and violet smoke rings. Inhale elsewhere first.)
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[*] posted on 29-3-2008 at 04:26


Wow, thanks! This is certainly not in stock at my local Lowe's, however. Unless I'm just oblivious.



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[*] posted on 29-3-2008 at 06:19


Quote:
Originally posted by MagicJigPipe
Wow, thanks! This is certainly not in stock at my local Lowe's, however. Unless I'm just oblivious.


Go to the Web page, enter your zipcode (or a neighboring one if you're feeling particularly paranoid), and see if it's available at another store in your region. I tried this for two different regions that I visit, and in each case, there was one store that had it in stock. I tried it for Los Angeles, though, and it looks like nobody carries it there.

The manufacturer's page for the product (and others) is here:

http://www.summitbrands.com/brands/FilterMateTips.aspx

They also have a store locator at the bottom of that page, but it looks like it just lists stores in your area that carry at least one of their products, not the particular one you want.

They claim that you can get the permanganate through their mail-order distributor, but only as 12 x 1.5lb for $108 or 6 x 5lb for $180. UPS ground shipping is $30 or $35 respectively for New York City.

http://www.cleaningcart.com/merchant2/merchant.mvc?Screen=CT...

So, the good news is that you apparently can get it shipped anywhere in the continental US; the bad news is that you have to get lots and lots. I'm not sure what I'd do with 14 kilos of KMnO4, short of reselling it; I wonder what maximum quantity you can ship without special handling?
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[*] posted on 29-3-2008 at 19:22


Quote:
Originally posted by MagicJigPipe
Geezmeister, why is it that you seem to only be interested in reagents and "syntheses" related to amphetamine production? Are you interested in anything else at all (non-drug)?


Wow, insult one of the elders of the hive. what a punk.



[Edited on 31-3-2008 by vulture]
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[*] posted on 29-3-2008 at 21:40


Whats with the ad hominem attacks? If you want to slander (These are feeble attempts) somone, why don't you do it somewhere where you woln't muck up useful threads. If you are so concerned about the HCS, why aren't you active in trying to make it happen? It seems you dont really care about this imaginary committe (I think he means the HCS) or the donations, just about satisfying a craving to put yourself above others.

To JeffB: Thank you very much for posting that! I now have a brand new bottle of KMnO4! I was relying on this little bairly full jar that I traded for. Now I can try some experiments with manganese heptaoxide!

If you are looking for more pure iodine you could always sublimate it with a little heat and deposit it on a cold surface. I heated mine in a small dish with a flask of cold water above it. Just make sure its not too wet like mine was, or the water will annoy you by condensing over the iodine crystals.
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[*] posted on 30-3-2008 at 00:26


To obtain dry iodine, crude iodine (filtered and pressed dry on a sintered glass filter or paper towels) is melted under conc. sulfuric acid.
The sulfuric acid prevents its vaporisation and enables the iodine to melt while taking up the moisture.
After cooling, a solid iodine disk is obtained:
http://www.versuchschemie.de/topic,5772,-Jod+in+interessante...
This gives completely dry iodine.
The disk tends to have inclusions of conc. sulfuric acid, so a final sublimation to obtain crystalline, dry and pure iodine is in order.

This is the industrial method for drying iodine! The german procedure and the pictures seen in the link are from me.
The procedure also contains the instructions to make the iodine from KI, H2SO4 and H2O2.




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[*] posted on 11-4-2008 at 10:30


Quote:
Originally posted by woelenJust take excess acid (how much excess does not matter, as long as it is in excess) and then add excess H2O2 (again, how much excess is not important, better take way too much than some too little).


i did just that to a J2/KI solution in EtOH, and you know what happened? all the precipitated J2 redissolved and now i'm left with a happily bubbling orange liquid. what did i make?
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