sauveurdumonde
Harmless
Posts: 33
Registered: 13-7-2021
Location: Canada
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Problems (and success) with CHI3 synthesis
I made some iodoform today, and I got a nice yellow product. Not before a few fails, though.
I first tried making the CHI3 with 5 g I2, and 0.8 g NaOH (1:1 ratio) as I thought the NaOH was mainly for dissolving the I2, like how KI and NaI
solutions dissolve I2 a lot easier... I was wrong. I added this dark yellow solution to excess ethanol. No reaction until after a few minutes, and the
solution went completely clear forming perfectly white crystals. (exactly like the image on the right). The reaction was slightly exothermic as it was
a little warm to touch. And, no, it was not warm from the NaOH dissolving, as I let the solution cool before reacting. This was obviously not CHI3.
When burned, no I2 vapour formed so this likely doesn't even contain iodine. I do believe it is an organic compound though, as it does slowly burn and
leave behind carbon
I tried the reaction again the next day but I used acetone instead of ethanol, and had a 1:2 molar ratio of iodine:lye solution based on this
equation:
3I2 + 6NaOH -> NaIO3 + 5NaI + 3H2O. There mas have also been some NaIO forming, which I thought would be like NaClO, which can make CHCl3 form
acetone.
Upon adding to acetone, absolutely nothing happened for a while. The solution stayed yellowy-red. I then added a small amount of NaOH, and the
solution went completely clear, then yellow, then forming pure white crystals (the actual product is the photo on the right.). Mildly exothermic like
last time.
Afterwards, I tried the exact same route but dissolved the I2 in excess acetone and made a seperate solution of NaOH in water instead. After adding
the NaOH solution to the I2 solution, a small amount of I2 gas was liberated, and then starting forming yellow crystals, which smell like a hospital.
CHI3 (left photo). This time, the reaction was endothermic.
I am baffled as to what these white crystals could be. I first thought it may have been excess NaOH precipitation but it happened after so much time
and these crystals are not water soluble. They seem to be hydrophobic, in fact, forming a small bubble around them when added to water or acetone.
Any suggestions about why these did not work properly the first two times, and any ideas what the white stuff is would be appreciated.
 
"There is a shadow of a nation behind you, the hope of a people... yet it may not matter. The Divide still stands against us."
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aab18011
Hazard to Self
Posts: 74
Registered: 11-7-2019
Location: Connecticut, USA
Member Is Offline
Mood: Moving out and setting up shop in my new chemistry hobbit hole
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I am currently trying to find all possible side reactions or issues. Can you maybe do a more conprehensive solvent test? Is it soluble in Ethanol,
Acetic Acid etc. Maybe some functional group tests.
From what I can see, if you used cold and dilute solutions for reactions then you will only get NaIO. If you used hot and concentrated, you will get
mostly NaIO3.
As far as I can tell, you didnt make any weird iodine conpounds. If you used ethanol you may have made an oil that has encapsulated your gooey white
crystals and thus why they wont dissolve in water. You can dry them and test them later to see if they still behave this way. With acetone, you may
have caused a condensation and iodination via some enol condensation. But im not really sure. Other pictures would be helpful such as reaction photos.
[Edited on 12-18-2021 by aab18011]
I am the one who boils to dryness, fear me...
H He Li B C(12,14) Na S Cl Mn Fe Cu Zn Ba Ag Sn I U(238)
"I'd rather die on my feet than live on my knees" -Emiliano Zapata
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