Ormarion
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Registered: 19-12-2017
Location: France
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Mood: Alkylating her DNA
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Carbon tetraiodide synthesis
Hello everyone, today a little post about the synthesis of a interesting halogenomethane i found while going trough very old books, carbon tetraiodide
As a note before we start, this synthesis produce a LOT of ethyl chloride vapors, even my fumehood wich is 1.280 CFM had a hard time to keep up when
too opened, if you perform this reaction, please work in a very well ventilated area
And also carbon tetraiodide is pretty toxic (DL50 in rat 19mg/kg), so keep it in mind, now to the synth !
Ethyl iodide, copper stabilized, was prepared a few weeks ago trough the classic I2/red P methode, and dried over molecular sieve to ensure it was
fully dry, as well as for carbon tetrachloride
In a 250ml 2 neck rbf (previously flame dried) was added 2g of anhydrous aluminium trichloride. A water condensor (that was later replaced with a
MgSO4 moisture trap) was placed on top of the rbf, as well as a gas inlet with a septum on the second neck.
-The reaction apparatus was then inerted with a few flush of argon gas, and 12g of dry carbon tetrachloride was added trough the septum by the help of
a syringe
-Around 48g of dry ethyl iodide was then measured and injected trough the same septum. Both reactant were mixed at room temperature and the liquid
slowly turned to a dark red color.
-Very slight heating (30°C) was applied and the condenser was switched to a moisture trap. At this time the solution became more and more "oily"
looking as carbon tetraiodide started to form and some ethyl chloride vapors were involved.
-After 30min of stirring i opened the argon valve on low flow in order to flush away all the ethyl chloride vapors for the next 15minutes, slight
heating up to 50°C was also applied to ensure full completion.
-After most of the vapors faded away the setup was disassembled and the remaining fumes were sucked away. The dry black solid was rapidly scrapped off
the rbf walls and was poured into a frit funnel to prepare for washings and vacuum filtration.
-At this step water can be added to both the filtered solid, and remaining product stuck to the rbf walls. However be aware that it will neutralise
the remaining AlCl3 and produced a lot of smoke. Surprisingly, water actually worked quite well with a little scrapping to remove all the crystals.
The dark cristalline product was then filtered under vacuum and washed with 30ml of water, before letting it dry on the pump.
-Finally the black powder was scrapped and weighted, giving a mass of 35g (88% of theorical yeild) wich is actually better than the 60% reported by
litterature
The product was then stored in a dark amber glass bottle over some argon, inside of my lab fridge.
You can see a few pics i took of the reaction, the litterature and finally a little youtube link showing the ethyl chloride vapors production and why
good air suction is so crucial ! I plan on recrystallizing it in xylene following Niklas input since it form beautiful crystals, will update with
pictures if i do
https://youtu.be/X3cplg_Gc-0?si=60zvVafbUZMl4OKW
Concerning waste management i just added it to my halogen drum, but considering it hydrolyze slowly to iodoform and iodine in water, i assume it can
be neutralised with thiosulfate
What is insane about this product is its density, of 4.32g/cm^3, it was honestly impressive to hold such a small bottle and feel it weighting so much.
Same as for the carbon to iodine molar weight ratio, where it represent close to 2% of the total molar weight
Overall, a rather "easy" and fast synthesis, might try to perform a IR analysis maybe.
Until next time folks :p
   
[Edited on 26-9-2025 by Ormarion]
[Edited on 26-9-2025 by Ormarion]
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Metacelsus
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Registered: 26-12-2012
Location: Boston, MA
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Cool. I'm curious why this reaction works. Is it the ethyl chloride vapors escaping that drive the equilibrium forward?
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Ormarion
Hazard to Self
Posts: 69
Registered: 19-12-2017
Location: France
Member Is Offline
Mood: Alkylating her DNA
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Its a halogen exchange so i believe it does in some way yes, its why i tried to make sure to remove as much as i could with slight heating, its also
maybe why i got a better yeild. But its still surprising its able to fix 4 iodine on the same carbon atom
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