Sciencemadness Discussion Board

Iodine trichloride

The_Davster - 21-10-2006 at 20:06

Figured I would post this, I just tried it with success, until the filtration of the crystals as I realized I had really stunk up my basement with a mix of chlorine dioxide and chlorine. Oops. ICl3 is interesting as it can be used as a substitute for chlorine gas in many reactions, including the chlorination of iodobenzenes.

2g powdered iodine is mixed with 1g powdered KClO3 in a 50 ml erlenmeyer flask. About a half mL distilled water is added.
Next, 4.5mL of concentrated (37%) HCl is added dropwise under vigorous magnetic stirring, keeping the temp under 40C. Addition takes around 10 min. After addition is completed, the mix which is now a yellow orange liquid, is stirred for 30 min more. During this time, long canary yellow crystals precipitate, which are then filtered off after cooling the flask. Do not wash the ICl3, it is too soluble in water.

Ventilation is a must for the Cl2 and ClO2 given off, not sure how much is given off, as it is just from unintended side reactions, but it is enough to stink up a room, even with my ventilation system going, which normally works quite well.

KClO3 + I2 +6HCl ---> KCl + 2ICl3 +3H2O

I am, however, surprised that the KCl and ICl3 do not end up forming KICl4

( I would have put this in prepublication, but I forgot to charge the camera, and did not end up isolating the ICl3 in the end.)

[Edited on 22-10-2006 by The_Davster]

guy - 21-10-2006 at 20:40

http://jchemed.chem.wisc.edu/jcesoft/cca/cca3/MAIN/CLI/PAGE1...

Looks doable on a larger scale with low temperatures.

Nerro - 22-10-2006 at 00:56

We did this in a practicum once, the crystals looks quite nice indeed and with some gentle prodding can be made into a fluffy ball that stores quite well in the fridge.

It is noteworthy by the way that ICl3 is not the solid that you see, the solid are crystals of I2Cl6, a dimer best described as Cl2-I-(ยต-Cl)2-I-Cl2 :) Basically the iodine nucleus is missing one electron pair because two of the chlorines took it and the hole it left behing is filled up by one of the lone pairs on a Cl of another ICl3.

Come to think of it I believe we may have used the I2Cl6 crystals later on in the practicum to chlorinate something like (N-PCl2)n with n=3 -> inf.

[Edited on Sun/Oct/2006 by Nerro]

woelen - 22-10-2006 at 10:32

I2Cl6 stores very badly. It gives off chlorine like hell and what remains is ICl. I have made ICl3 by leading excess chlorine gas over I2. This gives a yellow powdery solid, but when the excess chlorine is removed, then the ICl3 quickly looses Cl2 and ICl remains behind.

Nerro - 22-10-2006 at 10:34

We stored it at -18 C and it stored for two weeks.

The_Davster - 22-10-2006 at 10:38

Your fridge goes down to -18:o
Anyone know what temp it can be stored indefinatly at without undergoing decomposition? My freezer goes down to -25C ish.

[Edited on 22-10-2006 by The_Davster]

woelen - 22-10-2006 at 10:56

You probably even can store it at room temperature, but then you need to store it in an atmosphere of pure Cl2. If you store it in air, and you want to store it for indefinite periods of time, then I think you will not manage in any fridge, which can be purchased by the general public. If even at -18 C it only keeps well for two weeks, then I think this is not the chemical you should want for long-term stockpiling.

I also made KICl4, isolated it, and stored it in a glass vial.

http://woelen.homescience.net/science/chem/exps/KIO3+HCl/ind...

I still have some of this chemical left, and it looks as good as when I made it. This already is three quarters of a year ago. The only important thing is that the vial must be sealed very well. So, if you want something close to ICl3, then I would go for KICl4. On heating, it gives off ICl3 (which then quickly decomposes to Cl2 and ICl).

Edit: Made link work again.

[Edited on 26-2-16 by woelen]

Nerro - 22-10-2006 at 11:26

That might make a difference yeah, we had it in tightly sealed glass vials in the fridge. They came out weighing exactly the same as when they went in.

The followup experiment with the (N-P(Cl2))n worked fine.

I think the message here is, store it tightly sealid in glass in the fridge and it should keep pretty well.

Waffles - 24-10-2006 at 14:52

Quote:
Originally posted by woelen
You probably even can store it at room temperature, but then you need to store it in an atmosphere of pure Cl2. If you store it in air, and you want to store it for indefinite periods of time, then I think you will not manage in any fridge, which can be purchased by the general public. If even at -18 C it only keeps well for two weeks, then I think this is not the chemical you should want for long-term stockpiling.

I also made KICl4, isolated it, and stored it in a glass vial.

http://woelen.homescience.net/science/chem/exps/KIO3+HCl/ind...

I still have some of this chemical left, and it looks as good as when I made it. This already is three quarters of a year ago. The only important thing is that the vial must be sealed very well. So, if you want something close to ICl3, then I would go for KICl4. On heating, it gives off ICl3 (which then quickly decomposes to Cl2 and ICl).


leave it to our own mr. oelen.

i can't get over how nice the photodocumentation of your procedures is.

Edit(woelen): Modified link so that it works again.

[Edited on 9-6-16 by woelen]