raiden
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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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garage chemist
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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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zeppelin69
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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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garage chemist
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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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raiden
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Okay, I am thinking of using 1 molar solutions of KI and HCl - is this suitable?
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garage chemist
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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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raiden
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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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MagicJigPipe
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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.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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garage chemist
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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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woelen
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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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geezmeister
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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.
mostly harmless
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MagicJigPipe
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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)?
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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WizardX
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I2 from KI http://www.frogfot.com/synthesis/iodine.html
Albert Einstein - \"Great ideas often receive violent opposition from mediocre minds.\"
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MagicJigPipe
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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]
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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-jeffB
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| 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).
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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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MagicJigPipe
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Wow, thanks! This is certainly not in stock at my local Lowe's, however. Unless I'm just oblivious.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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-jeffB
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| 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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chemnut
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| 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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CyrusGrey
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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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garage chemist
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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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stoichiometric_steve
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| 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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