Author Topic: Home-made I2  (Read 8785 times)

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Optimus Prime

  • Guest
Re: Home-made I2
« Reply #20 on: November 27, 1999, 03:44:00 AM »
I read where the addition of aspirin to NaI or the like evolves HI (g) which can be piped into dh2o to give aq. HI.




  • Guest
Re: Home-made I2
« Reply #21 on: November 03, 2002, 09:56:00 AM »
Try this:
1. Dissolve 100g KI in 300ml 10% HCl
                  or in 107ml 28% HCl
                    ->300ml HCl 10% = 30g HCl
                    ->30g HCl/280g/L = 0.107l of 28% HCl
                    ->if using 28% hcl add 126ml h2o also
2. Add 100ml H202 (hydrogen peroxide 10%)(=10g H2O2)
     or 333.33ml H2O2(3%)(10g/0.03g/ml=333.33ml)

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

KI = 166g/mol
H2O2 = 34g/mol
2HCl = 36.4g/mol

SO -> 100g KCl = 0.602 mol
      10g  H2O2 = 0.301 mol 
      22g  HCl = 0.602 mol
->Need pretty exact amounts of potassium iodide and hydrogen peroxide, but excess hydrochloric acid is OK.  Thats why the recipe is for 30g equivalent of HCl when the balanced equation is for 22g HCl.
100% theoretical yield of I2 = 254g/mol x 0.301mol = 76.454g

As you add the H202, I2 falls out. This can
be filtered off, as it is only slightly soluble in water.
It is a good idea to wash it with some distilled water, as it might still contain some KCl.
When I do this in my dreams, I squeeze the filter to get the I2 crystals dry (not completely).
Then it can be purified by resublimation (see above).

reaction mechanism (:-)):

The H2O2 gives off oxygen ions.
These react with the hydrogen ions
from the HCl to form H20. The H202 is now H20, too, since the O left it, because they argued the whole time. Not a very stable relation, that H202.
Now that chlorine ions from the HCl are alone.
But they don't want to be alone. They want to be satified. So they grab the K ions from the KI, since they are stronger than those iodine ions.
Now the iodine ions are alone. And they want to be satisfied, too. So they react with temselves to form I2 :-).

D.G.(original) + Myles(modified)


The BEE game is why im here top score 300 points


  • Guest
> 300ml 10% HCl or in 107ml 28% HCl > ...
« Reply #22 on: November 27, 2002, 12:16:00 PM »
> 300ml 10% HCl or in 107ml 28% HCl
>    ->300ml HCl 10% = 30g HCl
>    ->30g HCl/280g/L = 0.107l of 28% HCl
>    ->if using 28% hcl add 126ml h2o also

You assumed that all the liquids have a density of 1.0. They don't! 28% HCl has a density of ~1.14, and 10% HCl should be around 1.05 if I remember correctly.
The error might be small in some cases but rather big in others!

I'm not fat just horizontally disproportionate.


  • Guest
simplest I2 from povidone feed-stock solns.
« Reply #23 on: December 04, 2002, 10:32:00 PM »
Before I realized I could use ether to x-tract the i2 from the Ka/I soln that resulted from the hyp/hcl additions, I played around with feedstock 1% iodone soln (not povidone, some other shit, real soapy) anyway... I found hcl/hypo didn't precipitate, but formed a dark sludge and seperable light top watery layer. This can also be achieved by gentle heating since it seems to destroy the solvating properties of the shit. So I then proceed to sublime it out of the goo using a big cold finger. It worked but not well. THEN I figured, "I should just distill this shit into dH20 since the soap doesn't come over" SO lo and behold I hooked upi a short pcv tube to a  thermometer adapter on top of the flask and stuck the other end in a jug of dH20. And lo and behold Tons of shiny black crystals dumped into the reciveing jar. You should probably add some sort of trap as when the I2 vapors hit the cold water they SNAP very loudly and cause considerable suck back. but this gave me totally pure super simple I2 fromtheir most prized concoction to keep us from doing just that. Took four hours altogether, haven't really tallied up yield since we lost abunch to fuck ups, breaking flasks (fun) etc. and I'm sure can be tweaked indefinitely for extraction from aqeous solns.
also if you have pure KI Cl gassing is definitely the way to go. And using NP's to extract I2 sure deserves to be explored some more. Have fun....


  • Guest
thanks pebble i tried your method and it ...
« Reply #24 on: March 27, 2003, 10:10:00 PM »
thanks pebble i tried your method and it worked fine for me and to think i even never did anything with chem before i got my some real nice iodine crystals


  • Guest
« Reply #25 on: March 23, 2004, 12:40:00 AM »
so what you're saying is basically boil your iodine after adding HCl and H2O2 in one flask and pipe the vapours into a container of water with ice in it and that's it? that's really neat actually.

I customarily use distilled naptha as a solvent, i was wondering if that would be a good way to fully dry the iodine - separate off the water residual by dissolving the iodine in the naptha and washing off the residual watery stuff. i would think pentane/hexane would be the perfect solvent for this since both dissolve very little water and the distilled fraction that is made boils off mostly before the iodine hits it's sublimation temperature (127*C isn't it?)... then put the iodine in distilled naptha solution on a dish and evaporate slowly,  maybe sitting on something warmish (fast evaporation results in rapid cooling and condensation of water from out of the air)... or maybe in a flask in a hot water bath with a hose feeding over to a drying tube to prevent water from entering while letting the naptha vapours escape.

or simpler: i have a copper condenser, which i dont' think would be suitable to collect the iodine when subliming it, however, it should be fine if a layer of plastic wrap is put around the condenser tip where it goes into the flask to work as a cold finger.

I've noticed those iodine 'washes' in the pet shops too - they contain '.6% available iodine' or something like that, i don't know what the real number of total iodine content is, but it's cheap and comes in a large 500ml container (at that percentage that works out to 3g, where i am works out about half the cost of the wee 25ml bottles from the pharmacy)


  • Guest
« Reply #26 on: March 23, 2004, 03:29:00 AM »
There seems to be only one main iodine tincture available local to me, a very expensive 25ml with 25g/L each of KI and I2 in alcohol, so i thought i might sit down (while buzzing on some presently but probably not much longer to be legal piperazine stimulant ;) ) and work out the precise stochiometry of the reaction so that it can be done more successfully

H2O2   34.0146g/mol
KI   165.9945g/mol
I2   253.809g/mol
HCl   36.5609g/mol

25g/L KI = 0.150607 mol/L
25g/L I2 = 0.098499 mol/L


in 25ml, by weight:
0.625g (0.003765 mol) KI
0.625g (0.002463 mol) I2


2(KI) + H2O2 + 2(HCl)
   2(H2O) + 2(KCl) + I2


2x(0.003765) + 0.003765 + 2(0.003765)

the weights of each would be as follows (per 25ml bottle):
KI: 0.625g
H2O2: 0.128g
HCl: 0.137g

the H2O2 needed to provide the
correct amount would be the following,
depending on the concentration of the

1%  (0.01g/ml) 12.8ml
3%  (0.03g/ml) 4.26ml
6%  (0.06g/ml) 2.13ml
10% (0.10g/ml) 1.28ml
45% (0.45g/ml) 0.284ml

the amount of HCl solution at varying
(common) concentrations:

28% (0.28g/ml)   0.4892ml
30% (0.3g/ml)   0.4566ml
31% (0.31g/ml)   0.4419ml
32% (0.32g/ml)   0.4281ml
33% (0.33g/ml)   0.4151ml

Once the proper proportions of reagents are mixed together, the potassium iodide will be turned into potassium chloride and the iodide ion turns into iodine. The usual thing to do from here is to add lots of water to dilute the alcohol and then the iodine will precipitate from the solution. However, this is inefficient in two ways - one, the alcohol, no matter how dilute, is going to cause some amount of iodine to remain in the solution. And every ml of water, which reduces the amount held by the alcohol dissolves iodine to the rate of 0.03 g/100 mL at 20 C, that's 300mg dissolving into a litre of water.

I think the best way to proceed would be to first convert the iodine into salts, then boil it down and all the pesky alcohol goes away. The precise molar amount of base to use on the 25ml tincture bottle to convert the iodine is 0.004926 moles, if NaOH (molar weight 39.99707g/mol) were used, this would mean 0.197g of NaOH per bottle of tincture.

The total number of moles of iodide ions in the solution would thus be

moles KI + 2x moles I2 = moles I+

0.625g (0.003765 mol) KI
0.625g (0.002463 mol) I2

0.003765 + 2x(0.002463) = 0.008691 moles of iodide ions

Okay, so now we have a mixture of sodium iodide and potassium iodide, we can safely boil it down to dryness without fear of losing I2 or stinking and staining up the kitchen ;) both of them melt at 600+ degrees C, so there's no concern of decomposition or anything, one could bake it in the oven at 250°C until it absolutely has no moisture left in it.

Thus we have defeated the first source of losses.

then, we have 0.008691 moles of iodide ions which we can turn into half as many moles of I2, so we can then turn it back into iodide ions...

back to the formula:

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

okay so that's
iodide ions 0.008691 moles
H2O2 0.0043455 moles (0.1478g)
HCl 0.008691 moles (0.3177g)

ppl can convert their for their own acid and peroxide, but mine's 280g/L HCl and 3% peroxide, so for me that means:

HCl (280g/L) 1.1348ml
H2O2 (30g/L, 3%) 4.9266ml

per 25ml tincture bottle you start with.

Now with this home made Na/K/iodide salt, which is nice and dry, you can add those two reagents, and since you hardly added any water, it's not hard to dry it again.

Because the whole thing is done with proper molar ratios, one should get around 95% yield. For each little 25ml bottle of tincture, theoretical yield of total I2 is 0.0043455 moles or 1.1029g , so it should be possible to get 1.047g out of each little bottle.


  • Guest
from kelp?
« Reply #27 on: March 23, 2004, 03:41:00 AM »
Let's say that a person happened to have a quantity of kelp and they knew the amount of iodide ions contained in it, then the same thing could be done to it (well, more or less, but not so stochiometrically accurate), ensure it's iodide by adding the stochiometric amount of sodium hydroxide, then filter it all out, defat the solution, boil it down to dryness then add the peroxide and hydrochloric acid and wash out rubbish with cold water.

does that seem reasonable?

also, as an alternative to sublimation, could one repeat the process? this would isolate the iodine from the kelp and then the second pass of the process would isolate the iodine from the rubish remaining from the first time.


  • Guest
kelp, I2, and iodate
« Reply #28 on: March 23, 2004, 06:59:00 AM »
i believe (someone will elaborate, this is well known for sure) that for extracting I2 from seaweeds that collect it, the method is:

  "the seaweed is dried then burned. The ashes are leached and, from the solution, K2SO4, KCl, and NaCl are removed by crystallization. The filtrate is evaporated and the residue treated with H2SO4 and MnO2 or with Cl2. The liberated I2 is collected and purified."

  i love the fact that you're going DIY, but i'd just like to use this post to say that any usa bees who are buying their I2 from tincture or elemental I2, well...that can have a high cost, money and freedom-wise. everyone who sells I tincture knows what is up. maybe they're ok with making money off it, but even then it is still much cheaper to just order some iodide or iodate.

  either one is pretty cheap, usually as USP or ACS grade. some sell high, but some sell low, and in the past i've found ACS KIO3 at very low cost per mole of I2. when you start looking at 500g+ quantity you see that you're better off ordering a lot of this once than going to the tincture. much cheaper per mole. cheaper even if you get way more I2 than you'll ever need.

  since i mentioned the iodate, i suggest everyone try a fun reaction not mentioned in the hive before:
  put some dH2O in a flask. add some oxalic acid. it doesn't have to be very much, but given the cheap OTC-ness of the 99% hydrated acid, add as much as you want. add some iodate or iodic acid or I2O5. heat, and place your sublimation apparatus (like an upside-down flask, jug, or bowl with a ice-filled towel wrapped around it, or a metal bowl containing icewater resting on top) over the neck of the flask immediately. if you add iodate to boiling oxalic solution, you get instant and heavy production of iodine vapor. you will also note vigorous gas evolution. it is CO2, there is no CO formed, or side I products, as far as i can tell.
  the reaction proceeds in direct relation to heating.
  i think that you need at least 2 moles oxalic (don't forget that yours is probably the hydrate if you're actually weighing) per mole iodate salt. or acidify with some other acid, then add 1 mole oxalic. the free acid of course is different, but you might as well add excess oxalic anyways. 

Confucius say: "buy a lifetimes worth of chemicals and glassware now, while iodides, toluene, and everything else is still available. maybe future hold no love for chemist without a license to practice chemistry. buy discreetly and store in remote location"


  • Guest
> I think the best way to proceed would be...
« Reply #29 on: March 23, 2004, 09:43:00 AM »
> I think the best way to proceed would be to first convert the iodine
> into salts, then boil it down and all the pesky alcohol goes away.
> The precise molar amount of base to use on the 25ml tincture bottle
> to convert the iodine is 0.004926 moles, if NaOH (molar weight
> 39.99707g/mol) were used, this would mean 0.197g of NaOH per bottle
> of tincture.

Basifying I2 and evaporating will produce a mixture of NaI and NaIO3, which on acidification will react back to I2. No need to add H2O2 for the elemental iodine in this case.

The H2O2 oxidation of iodide is slow, and I assume some H2O2 will be lost due to decomposition, so it's not necessary to go overboard with your significant digits during stoichometry calculations, just add an amount that is somewhat bigger than the theoretical requirement.

The iodide/iodate reaction is pretty fast, you mix the solutions and solid I2 will precipitate immediately. If you can get your hands on NaIO3 or NaIO4 and NaI then your I2 problems will be over.


  • Guest
« Reply #30 on: March 24, 2004, 10:21:00 PM »
i forgot what the rules with significant digits was so i kinda winged it (praise bob that spicey is going to redo his highschool chem  :-[  )

okay, so anyway swis found some 'iodine pet shampoo' at his local pet store and the bottle was 30 something and had 19.7mg/ml of 'crude iodine'

swis set up a little thingy like the one with the bubbling and shiot, chucked salt in the shampoo stuff to stop it frothing, and spent several hours being frustrated - it seemed iodine would sublime for a moment or two then stop and all this distilling business starts happening.

Okay, so that was a wrong turn. Upon inspecting the solution after it cooled, swis discovered that it had separated into layers, a reddish layer on top and a thin black layer at the bottom. swis decided that the bottom layer was where all the 'crude iodine' was hiding, and after rinsing the residue out with hot water after sucking up the thin black layer with a baster to remove the majority of it, swis experienced the usual eye and nose irritation as the iodine sublimed out of the container and the water etc...

so swis tried the boiling bubbling thingy with this oily shiot, but this was frustrating. the residual water distilled across first, and then some kind of oily stuff which didn't seem to be incompatible with the vinyl hosing started coming across.

One more incident of suckback made swis give up on this bubbling/sublimation nonsense and got a nice big capacity vacuum flask (from the charity second hand shop, old tin thing with a very wide mouth) filled it with ice and put a small earlenmeyer flask in it and just let the vapours go into that.

anyways, after some deliberation, swis decided that whatever the stuff that was dissolving the iodine must have been some kind of fatty acid stuff (it kinda smelled like burnt vegetable oil) and that for some reason this stuff would continute to occlude the iodine and be nasty and bump (bumping causes suckback in the bubbling through sublimation, i think it should only be used maybe as a resublimation method, when you know you're not going to have to wait for untold liquid to distill across)

so, rather than do that, swis added a load of sodium hydroxide to that mass, some water, some heat, stirring... swiss the silly fool tried to scrape the crud of the bottom of the flask but with his bodgy bent wire rod and how hot the little 250ml flask was a section was taken out of the side of the flask... swis cast another broken piece of glass in the trash and more or less finished up, the evening was over.

the end result is that swis filtered this basified iodo crap and a nice clear yellow/reddish liquid which boiled down to start precipitating crystals of sodium iodide and friends

Os: so adding base to the iodine makes it into iodides and iodic acids, and this is reversible without using peroxide? then i guess with that liquid one just dumps some HCl into it and voila?

cool, nice to know.. this means dont' have to use the peroxide in the extraction from the iodine shampoos.

So, here's my little story, for everyone else who has noticed they don't sell the 500ml bottles anymore and look at you weird for buying two bottles.

the vet shop girl who serves you gives you the bottle in a plastic bag with a nice warm smile and you go home feeling so much better :D


  • Guest
« Reply #31 on: March 24, 2004, 10:31:00 PM »
swis can't remember now *exactly* what he did... thinking about it now, what would happen if one added a strong acid to a solution of potassium/fatty acid salts - i would think that would steal all the potassium and leave you with two layers. thing is, what kind of vegetable or animal oil is more dense than water? or was this just a factor of having what i estimate to be 9g of iodine (very dense) in it... then again i don't know what you get if you dissociate sodium lauryl suphate either or any other synthetic detergent.

I don't remember putting acid in before cooking it up so i think that it may have just been the salt that did it. sodium chloride does have a pKa of 6.5 or something like that, maybe that was enough. I know that soap precipitates from insolubility sink, but if the oil is dissociated via acid it goes to the top.

The bottle said that it was a 'low foaming' detergent in the formula, so maybe the oil i was distilling was turkey red, sulphonated castor oil, which i know conditions textiles in preparation for dyeing, and softens hair. the shampoo is supposed to be to condition the coat and eliminate skin conditions, and the skin conditions are fixed by iodine so the special soap must be the conditioner.