hkparker
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Reaction between iodoform and chlorine
I'm considering doing a YouTube video on Iodoform (synthesis, properties, etc). I've got the synthesis down but I was thinking about possible
reactions and I'm wondering what would happen with chlorine. I would imagine chlorine would strip the iodines to make CHCl3 but wouldn't it also
remove the hydrogen to make CCl4? Could be useful if it does! I'll be trying this by experimentation soon but I was wondering if anyone knew.
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"Nothing is too wonderful to be true if it be consistent with the laws of nature." -Michael Faraday
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plante1999
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I dont think this will work , but it need a try . Take notte that the I2 will disolve in the chlorinated solvent.
I never asked for this.
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hkparker
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I did it. The reaction was quite exothermic and iodine was produced as well as a solvent. I would imagine this is CCl4. The iodine partly dissolved
in the solvent and it was very very volatile.
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Rogeryermaw
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the extreme volatility certainly sounds like carbon tetrachloride. did it give off a sweet odor?
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hkparker
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I tried to smell it and I got a big wiff of extra chlorine, so I couldn't tell. By the time I got back it was all gone (it was sitting in the sun and
I didn't make much). I will try this again and get a more accurate smell of it and idea of its physical properties.
So if this is CCl4 and I want to save it distillation would be hard as its contaminated with iodine. Im thinking I could add some mossy tin and react
to form SnI4, that way when I distill there will be no more volatile products, sound good?
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AndersHoveland
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Quote: Originally posted by hkparker  |
I was thinking about possible reactions with iodoform and I'm wondering what would happen with chlorine. I would imagine chlorine would strip the
iodines to make CHCl3 but wouldn't it also remove the hydrogen to make CCl4?
I did it. The reaction was quite exothermic and iodine was produced as well as a solvent. I would imagine this is CCl4. The iodine partly dissolved
in the solvent and it was very very volatile. |
Did you do the reaction in water? That could greatly affect the outcome of the reaction. The chlorine disassociates in water to form hypochlorous acid
and hydrochloric acid.
The iodine atoms would easily be substituted with hypochlorite. The intermediate would not be chemically stable, so likely formic acid would be the
oxidation product.
Because iodine atoms have a larger diameter, they substitute out easily, whereas it is generally not feasible to substitute out chlorine atoms from an
alkane because the reaction is so slow (months at room temperature, or an hour of refluxing with aqueous base)
You might try reacting dry chlorine gas with iodoform dissolved in chloroform, I would be somewhat surprised if there is a reaction (if there is a
reaction I think you would only get chloroform and iodine chloride)
One interesting aspect of iodine chemistry, however, is that iodine is surprisingly reactive when it acts as a reducing agent. However, since
iodine is itself generally an oxidizer, we generally do not encounter reactions were iodine acts as the reducing agent.
One suggestion, keep the reaction out of direct sunlight and do not leave the chlorine or iodine to stand with the other reactants for more than an
hour. Alkanes can be halogenated by a free radical cascade mechanism, and this can obscure your results.
[Edited on 9-6-2011 by AndersHoveland]
I'm not saying let's go kill all the stupid people...I'm just saying lets remove all the warning labels and let the problem sort itself out.
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Jor
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You can test if it is CHCl3 or CCl4 by adding the liquid to warm sodium hydroxide solution, and let it stand. I don't know how long the reaction
generally takes, but the chloroform will be hydrolysed to formate, and CCl4 will not react and will remain as the lower layer in the liquid. I however
think you made chloroform, and not CCl4.
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hkparker
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thats a good test Jor, thanks. why don't you think the hydrogen was replaced with chlorine? just not enough reaction time/chlorine?
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Jor
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Because the radical reaction between chloroform and chlorine is very slow at RT AFAIK. I think it is possible to make CCl4 by bubbling chlorine into
boiling chloroform under strong UV-irradiation, but the reaction is probably slow and unefficient. In industry it is done at high temperatures in the
gas phase. When exchanging the halogens, I don't see why that hydrogen would somehow become 'activated'. But again I'm not sure so you should test it.
Did you simply lead chlorine over solid iodoform?
Also be sure to use a large excess of Cl2 or you might get partly chlorinated products (like iododichloromethane?).
And this would be a very expensive way to make CCl4, unless you can constantly recycle the I2 very efficiently and have loads of time.
But then I would try bubbling chlorine through strongly irradiated (blacklight) boiling chloroform. Or if you can get CS2, chlorinate and reduce that.
But I think this is purely an experiment to see what's happening and not to actually wanting to prepare CCl4 for later use? 
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hkparker
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ok, that makes sense. I have read about making CCl4 from chloroform and chlorine but didn't realize it was at such extereme conditions. I led an
excess of dry chlorine over solid iodoform and did consider that some partially chlorinated products could have formed so I was sure to use an excess.
thanks for the help!
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"Nothing is too wonderful to be true if it be consistent with the laws of nature." -Michael Faraday
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AndersHoveland
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| Quote: Originally posted by Jor | | I think it is possible to make CCl4 by bubbling chlorine into boiling chloroform under strong UV-irradiation, but the reaction is probably slow and
unefficient. In industry it is done at high temperatures in the gas phase. When exchanging the halogens, I don't see why that hydrogen would somehow
become 'activated'. |
Leaving chloroform with dissolved chlorine in direct sunlight will very efficiently produce carbon tetrachloride. After only several hours, much of
the chloroform will have reacted. Since it is a radical cascade mechanism, it only takes a single activating photon to cause the reaction of about 40
molecules. If I remember correctly, it requires a short wavelength, typically UV, although bromination can be done with blue-green light.
Alternatively, vaporized chloroform could simply be heated to 400C with chlorine.
Actually, the hydrogen in chloroform might actually be somewhat 'activated'. Consider the rt reaction between chloroform and acetone to form
"chlorobutanol".
I'm not saying let's go kill all the stupid people...I'm just saying lets remove all the warning labels and let the problem sort itself out.
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Rogeryermaw
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a boiling point analysis may also help if you can isolate the liquid. CHCl3 60o vs carbon tet at 76o.
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hkparker
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Gave it a try, and filmed it.
http://www.youtube.com/watch?v=OARF9IIeHVA
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peach
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Thanks for the video Hk!
[Edited on 12-6-2011 by peach]
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hkparker
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No problem!
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"Nothing is too wonderful to be true if it be consistent with the laws of nature." -Michael Faraday
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woelen
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Hmmm... I missed this thread on iodoform and chlorine. I already posted an experiment in the other iodoform thread, which is in the organic chemistry
section. I repeat this post over here:
-----------------------------------------------------------------------
I have done a few experiments to check what happens with this reaction. I found it sufficiently interesting to make a small (text-only) web page about
this experiment:
http://woelen.homescience.net/science/chem/exps/exppatt.cgi?...
The second experiment describes what happens when chlorine gas is passed over iodoform. Based on the results of this experiment I'm almost 100% sure
that no CCl4 is formed, but only CHCl3 and possibly lower substitution products like CHCl2I and CHClI2.
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woelen
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Thread Pruned
15-11-2011 at 03:25 |
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