Intergalactic_Captain
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Separation of Iodine from Xylene
All right, I've already fucked this up and would like to avoid any further mishaps. It began with an attempt to separate elemental iodine from 7%
tincture by the bleach/acid method. I used H2SO4 and what I can only assume was a horribly wrong amount of normal 5% bleach. The problem was,
though, that as soon as the crystals started to form they just went back into solution. I tried adding more bleach and acid, but nothing happened...I
just ended up with a yellow solution with some amount of an unknown, insoluble white salt at the bottom.
Not knowing what to do, I added some baking soda and noticed that the solution became darker. So, I grabbed a quart of xylene and added a bit...It
took up the iodine, so I added more baking soda and xylene until no more color change was observed.
So, I am now left with ~500mL of saturated iodine/xylene solution. I've been looking around trying to figure out how to separate the iodine out, and
have a couple of ideas. First, my original idea, is that since mixed xylenes boil from around 100-110C, I could heat it with a coldfinger apparatus
and try to sublime the iodine out. The problem, though, is that I am afraid that whatever xylene evaporates would wash the iodine off the condenser
and right back into solution.
My second idea is to allow the mix to react with aluminum and form AlI3. From there, I could evaporate the solvent and decompose the AlI3. I have no
idea, though, what I could react it with to yeild elemental iodine or whether this is even a feasible route. I was originally thinking AlI3 plus 3
moles water to iodine and Al(OH)3, but I'm unsure as to whether this would work or just form a hydrated salt.
I have no idea what to do, and I need the Iodine, so if anyone can validate either of these methods or has a feasable route it would be greatly
appreciated.
[Edited on 12-29-06 by Intergalactic_Captain]
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Fleaker
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"I was originally thinking AlI3 plus 3 moles water to iodine and Al(OH)3, but I'm unsure as to whether this would work or just form a hydrated salt."
You would actually get Hydroiodic acid from it, just as with AlCl3 or AlBr3, both of which hydrolyze and form the amphoteric Al(OH)3 and the
corresponding binary acid (HCl + HBr). Basic chemistry.
I've never extracted iodine from tincture before, as it was easier to just buy some (not anymore), but then again, I never use it for anything. I
would probably evaporate out as much alcohol as I could, then when its as saturated with I2 as possible, add to cold water and filter it. Then pop
them in a dessicator.
It is easier to just buy KI or NaI and work from there using your understanding of reduction/oxidation.
As for your present quandary, I do not think adding aluminum (foil or powder) to the xylene would be a good idea, you might even put some iodine onto
your xylene (after all, aluminum halides are lewis acids, needed in Friedel-Crafts akylations). Couldn't you just leave out the xylene until it
evaporates away, leaving iodine crystals? Sure, you'll lose some iodine to sublimation, but its better than the vicious circle that a cold finger
would be...
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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roamingnome
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intersting becuase i have the exact same issue too... since im not in a hurry to use the iodine for anything its just hanging out.
i was going to use simple distillation through a "coldfinger" as you call it... or vaccuum
next time use DCM so it can distill faster... thats what i said to myself
but now i have a mission, so ill tell you tommorow what occurs
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evil_lurker
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Most effective method I've used is HCl/H202... put them in the right proportions, add water and watch the crystals crash out.
Filter and resublime as necessary.
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Intergalactic_Captain
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Damn....I can't believe I didn't realize the HI thing... I should have realized that H+ was missing from the equation. As for the AlI3, I was under
the assumption that it may work as several prep's for other Al halides took place in benzene or toluene and figured xylene may work. That, and it's
the only aromatic solvent I currently have on hand.
I would have used DCM, except for the fact that I need every drop I have for a future experiment. That, and I was afraid it may go to DIM, though I
now realize that that only happens in the presence of I- and not I2.
A quick whiff of the mix reveals more iodine than xylene, so I don't think evaporating out the xylene will work...Actually, that's why I grabbed it in
the first place - A high boiling solvent should allow more sublimation than evaporation.
Is there any way I could take it to an iodide while in solution, then just filter it out and redox it to the element? I can't think of any way to do
it, and have found nothing on the prospect of doing it in a non-polar solvent.
Right now, it looks like the coldfinger approach is my best bet, but I'd really rather avoid it if anyone can come up with a better method.
If you see me running, try to keep up.
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roamingnome
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Preparing for this operation im realizing it will be a slow pain. I looked at adsorbtion methods even. I consider the old standby of freeezing
thawing. If it where 1822 this might be a valid converstion but in 2007 i feel well... anyway
looking at the vapour pressures a tall column will prevent loss of iodine, but the vapours probably mix just as well... good luck chap
Mixed Xylenes
Vapor pressure: 5, 6, and 6.5 mm Hg at 68ºF (20ºC)
Vapour pressure: 16 mm Hg at 37.7 C
(bit a varation from page to page)
Iodine
Vapor pressure: 0.030 mm. at 0°; 0.131 mm. at 15°; 0.469 mm. at 30°; 2.154 mm. at 50°; 26.78 mm. at 90°
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roamingnome
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In the year of our Lord 1918
I addressed correspondence to a fellow associate and relayed the present quandary.
With Godspeed he parlayed to me that he constructed such an apparatus that would greatly benefit all who were not nimble enough to keep iodine out of
xylene.
He further elaborated that this device was so great that someday it would be named after him, but I scoffed saying who would name a piece of glassware
after such a strange name as Dean Stark…..
Since I don’t have one I failed in simple distillation attempts. Further more freezing only produces a yellow slush. I’m glad that I don’t need
iodine at the moment sorry….
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Eclectic
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Sodium hydroxide solution will extract halogens from hydrocarbon solution as a mixed halide/halate. Reacidify to recover your halogen.
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Intergalactic_Captain
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I checked my "Inorganic Chemistry" by Remsen last night and found exactly that reaction, and ended up doing it. I was wondering if someone would beat
me to it...
I'm just working up the nerve to try the extraction again. In the meantime, my leftover xylene still has a yellow hue - It's still transparent, kind
of looks like urine. Anyone know what this is? I read something about a xylene-iodine complex, but figured that the lye would pull kill it.
Activated carbon does nothing, which I half anticipated. Is it possible that I somehow iodinated my xylene, or is this just a stubborn complex that
won't give up?
If you see me running, try to keep up.
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Fleaker
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Good idea Eclectic. As I recall, what you get depends on what the temperature/concentration of the NaOH solution is. Intergalactic_Captain, you may
well need to use a separatory funnel to get proper mixing and therefore fast reaction.
I do not think you added iodine onto your xylene. I'm no expert at all with organic chemistry, but I think you would need more vigorous conditions to
put iodine onto xylene. Others correct me if I'm wrong, but doesn't it get easier to add halogens as their atomic weights increase? As in it would be
easier to brominate, than chlorinate? That is where I'm curious!
[Edited on 30-12-2006 by Fleaker]
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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Ephoton
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ive always used persulfate and hcl or sulfuric. works same as lurkers. saves on peroxide too. yep id stick with the hypo/halide extraction. caustic is
getting harder to get here too.
funny still can get it but many places are stopping to supply it.
e3500 console login: root
bash-2.05#
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Intergalactic_Captain
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red devil stopped production last year, hence the problems
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roamingnome
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hydroxide is still around, just start making biodiesel and experience a little "shrinkage" if you know that term....
the problem is, acidic water is where the iodine was first.... the non polar was used to grab it.
so i have iodine in acidic water. adding h2o2 will now participate the crystals? Im dealing in gallons here for closed loop water treatment for
RV's and off-grid water conservation.
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UnintentionalChaos
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Or take up soapmaking. There are many soap supply companies online who will sell both sodium and potassium hydroxide. Generally, they offer a 2lb (in
the US) size to avoid hazmat fees. One company I found would send up to 33 two lb packages in one order (but that would be SLIGHTLY suspicious if it
wasn't an order from a business).
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Intergalactic_Captain
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I didn't mean it wasn't around...I meant that "Red Devil" brand lye, the easiest to get, cheapest lye (in 1 lb containers, at least) in the U.S., is
no longer in production. My dad had a hell of a time tracking it down last year, and finally found some for $33/12 pack at a hardware store. It's
odd, though...he knows quite a bit of chemistry and doesn't realize it...As long as he can make money, he doesn't need to understand how it works.
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roamingnome
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i dont now how you voyage has gone, but just for the record, as you orginally thought, DCM turns out to be a funky solvent for iodine. It formed a
water iodine DCM miscible layer.... not too helpful
heptane ether mix turned out to be more amiable
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