thunderfvck
Hazard to Others
Posts: 347
Registered: 30-1-2004
Location: noitacoL
Member Is Offline
Mood: No Mood
|
|
Iodine extraction
Hello hello.
Okay. I got 10 bottles of I2 tincture. It's time for another extraction. The first time I did it I first based the solution until it went clear
with NaOH.
Question:
What is chemical equation for this reaction?
2NaOH + I2 --> NaI + NaIO + H2O
That's so it. I don't even have to bother asking. I should erase that but nah, I'll leave right there in the open so you can all
worship me. 
This is done because if HCl/H2O2 were directly added to the tincuture, you wouldn't get all of the I2 out as it is slightly soluble in the
water/minute EtOH.
Okay, so it's based until CLEAR. Is this an indication that all of the I2 has reacted with the NaOH? ie. to hell with calculating, just add it
until clear baby!...but some of us still will persit with the calculations...Ah, the benefits of being lonely.
The solution is then boiled off (too much heat no good? Does it decompose, that powerful ionic NaI & KI?)...to dryness! Then you collect the
crumbly yellowish/brown stuff, grind it up good and proceed with adding your HCl and H2O2...
I recall reading that because of the presence of NaIO, not as much H2O2 needed to be added. Comments?
For the sake of completion...
2NaI + 2HCl + H2O2 ----> 2NaCl + I2 + 2H2O
And BTW, this is not my original idea. The whole thing with adding base to the tincture...I stole this from the Hive and brought it here to build up
our arsenal. I THINK it was geezmeister who handed out this one...
And that's really about it, I do believe.
It's much more fun this way, I think. An extra step which really helps stink up the house (my mom was not pleased...took quite some time for the
smell to leave...). What causes the bad odour? As far as I know, the only solvents in use were ethanol in the tincture and water, and these were
boiled off which stunk like holy hell.
Yes!
[Edited on 26-5-2004 by thunderfvck]
|
|
|
S.C. Wack
bibliomaster
Posts: 2419
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline
Mood: Enhanced
|
|
This is often written as 3I2 + 6NaOH = 5NaI + NaIO3 + 3H2O. And this is also in the Hive. And recently mentioned was doing this in alcohol. This is
Not A Good Thing.
You are right about the balanced equation, to a point. However, the hypoiodite decomposes quickly, so it is written like I just did. But before this,
the hypoiodite reacts with the alcohol, especially if it gets hot, as solutions tend to get when you add NaOH to them, or when they are boiled. This
gives iodoform, which has a very strong smell. Perhaps if you look closely, you will see a small amount of ~yellow precipitate. Doesn't take much
to smell at all. Though I suppose the hypo smells too.
So thats why things are done as they are in the Stims forum. The peroxide forms I2, and the HCl or other acid promotes this. If you add too much acid
and peroxide I suppose you can get ICl or HIO3.
|
|
|
thunderfvck
Hazard to Others
Posts: 347
Registered: 30-1-2004
Location: noitacoL
Member Is Offline
Mood: No Mood
|
|
Ah. Thank you for that.
3I2 + 6NaOH --> 5NaI + NaIO3 + 3H2O
Is this BALANCED equation, ie. the equation I shall use in the calculation of my yield?
I hope this can be answered quickly as I want to start this tonight.
|
|
|
thunderfvck
Hazard to Others
Posts: 347
Registered: 30-1-2004
Location: noitacoL
Member Is Offline
Mood: No Mood
|
|
ANYWAYS.
Went ahead and did it. Realize now that my balanced equation is the right one, in terms of calculating how much NaOH to use anyway. Theoretically 3.6
g of NaOH. It took about 4. Good good.
10 tincture bottles, 5%. d=0.89g/ml, ~26 ml's per bottle.
Added about 4 g of NaOH SLOWLY...After about 2-3 g, it started to clear up...3 g I was able to see the bottom of the flask. 4 g, it started to turn
much lighter, a very nice, rosey red color, still a bit deep. Cleared up completely, slightly yellow (iodoform?)...Temperature didn't exceed
27*C.
Agh. Fucking christ. I just realized that I was all scared about it being too hot and it's the damned hypoiodite that decomposes. Am I retard?
Yes. My honor is shattered. And I KNEW that the NaI and KI was strong enough to resist the forces, but I'm too damned tired for this I suppose.
Shit.
Oh well.
I put it out on a cookie sheet and I'm going to let it evaporate. Great. THat should take a few centuries. I need a bloody fan. Crapping on
christ's crucifix. Hey, that's a pretty good one. Nice.
ANYWHO. When I put the solution onto the cookie sheet, not much happened. Yes. A good observation I think. AND so I had a little bit of good stuff in my flask, so I collected it with water and poured it onto the cookie sheet
with the other stuff. Wow! Nice yellowish, cloudy precipitate. And now it's sparkling all over. It's really quite beautiful. There are
crystals growing on the bottom of the cookie sheet. That, combined with the crazy sparkling, is a nice way to end an evening, I think. So I bid you
all adew (is that how it's spelt?)...and goodnight!
[Edited on 26-5-2004 by thunderfvck]
|
|
|
S.C. Wack
bibliomaster
Posts: 2419
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline
Mood: Enhanced
|
|
You may want to split this up into a few experiments of equal volume and see which gives the highest yield. Such as peroxide/acid, boiling off
alcohol/adding as much OH as it takes to give a colorless solution, and seeing if adding the calculated amount of OH to hot, alcohol-free NaI3/H2O
gives a colorless solution. Or you can do whatever you want. May be best to learn by trial and error. I don't think the hypoiodite survives for
more than a day in solution. Not long, for sure.
And one thing I've found by trial and error, is that things don't go as nicely as these equations would lead you to believe. Even simple
acid/base reactions can go wrong, especially without heating. And there are always side reactions and unreacted precursors.
Anyhow, for those who don't know, the iodate is insoluble in alcohol and easily transformed into iodine later. I'm not so sure about
iodoform, though it can be useful for other syntheses. You should make some if you never have, for the hell of it. It has a distinctive look and
smell.
|
|
|
unionised
International Hazard
Posts: 5104
Registered: 1-11-2003
Location: UK
Member Is Offline
Mood: No Mood
|
|
Acording to my 1963 copy of the British pharmacopoeia (ie this might be wrong), tincture of iodine contains iodine and potassium iodide so adding the
peroxide and acid will get more iodine than just extracting it would. (you wouldn't extract the iodide, only the free iodine and, it's
easier to extract when there isn't an excess of KI there)
|
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
