simba
Hazard to Others
Posts: 175
Registered: 20-5-2011
Member Is Offline
Mood: No Mood
|
|
Question about iodine tincture + lye
I wanted some sodium iodide, and decided to get some from iodine tincture. I bought 10% iodine tincture and added lye to it, until the solution became
clear.
The problem is that the result wasn't exactly what I expected. What I got was a yellow precipitate which I don't know what it is, since sodium iodide
is a white solid which is soluble in water, alcohol and acetone, so I shouldn't get a yellow insoluble solid.
The lye I used contains aluminium hydroxide, sodium chloride and sodium carbonate besides sodium hydroxide, which I think none explain the yellow
stuff I got.
Does anyone know what is this yellow powder?
|
|
|
simba
Hazard to Others
Posts: 175
Registered: 20-5-2011
Member Is Offline
Mood: No Mood
|
|
Ok I think I found out already, the yellow solid is iodoform.
|
|
|
Chemistry Alchemist
Hazard to Others
Posts: 403
Registered: 2-8-2011
Location: Australia
Member Is Offline
Mood: No Mood
|
|
Did you get any Sodium Iodide?
|
|
|
ThatchemistKid
Hazard to Others
Posts: 132
Registered: 2-6-2010
Member Is Offline
|
|
[Edited on 1-10-2011 by ThatchemistKid]
|
|
|
simba
Hazard to Others
Posts: 175
Registered: 20-5-2011
Member Is Offline
Mood: No Mood
|
|
Probably some iodide was formed yes, but I didn't bother to evaporate the solution since judging by the amount of iodoform I got, not much iodide
would be recovered.
The problem was that iodine + NaOH will give sodium iodide, but iodine + NaOH + EtOH will give iodoform...my tincture used EtOH as solvent so it
messed up the reaction.
|
|
|
Chemistry Alchemist
Hazard to Others
Posts: 403
Registered: 2-8-2011
Location: Australia
Member Is Offline
Mood: No Mood
|
|
try evaporate the alcohol a bit but dont let the iodine to sublime...
|
|
|
Mixell
Hazard to Others
Posts: 449
Registered: 27-12-2010
Member Is Offline
Mood: No Mood
|
|
Remember, for every hypoiodite anion that is formed (and consumed to make iodoform) an iodide anion is also formed.
I2+ NaOH --> Na+ (aq) +I-(aq) +IO-(aq) +H+(aq).
[Edited on 1-10-2011 by Mixell]
|
|
|
simba
Hazard to Others
Posts: 175
Registered: 20-5-2011
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by Mixell  | Remember, for every hypoiodite anion that is formed (and consumed to make iodoform) an iodide anion is also formed.
I2+ NaOH --> Na+ (aq) +I-(aq) +IO-(aq) +H+(aq).
[Edited on 1-10-2011 by Mixell] |
I did the experiment again (now without alcohol), and this time I got a light blueish color solution, more than likely because of formed triiodide
ions, and seeing your equation I suppose hypoiodite ions are the responsivel for this, converting iodides to triiodides.
Anyway, I was wondering if other bases like sodium (bi)carbonate will work in place of NaOH, since this would make a cleanup much easier. Anyone
knows?
[Edited on 8-10-2011 by shivas]
|
|
|
simba
Hazard to Others
Posts: 175
Registered: 20-5-2011
Member Is Offline
Mood: No Mood
|
|
Ok, so I just tried the carbonate variation of this reaction, and it works good. The only difference is that it does not occur expontaneously like it
does with NaOH, and needs some heat to happen. Maybe NaOH also needs it, but since it releases heat by itself when dissolved in water, no external
heat needs to be applied.
I mixed iodine crystals (extracted from tincture), with sodium carbonate and then placed it in boiling water. In a few seconds the solution turned a
light-blueish color, then boiled down and powdered sodium iodide was obtained. Unlike NaOH, Na2CO3 can be cleaned away by simply mixing the product
with ethanol.
|
|
|
Chemistry Alchemist
Hazard to Others
Posts: 403
Registered: 2-8-2011
Location: Australia
Member Is Offline
Mood: No Mood
|
|
Is there a way to convert Sodium Iodide to Iodoform with out converting to to Iodine first?
|
|
|
AJKOER
Radically Dubious
Posts: 3026
Registered: 7-5-2011
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by shivas |
I mixed iodine crystals (extracted from tincture), with sodium carbonate and then placed it in boiling water. In a few seconds the solution turned a
light-blueish color, then boiled down and powdered sodium iodide was obtained. |
Actually, characteristic of Iodine, there is a fast disproportionation so in addition to sodium Iodide there will be some Sodium Iodate.
|
|
|
Ephoton
Hazard to Others
Posts: 463
Registered: 21-7-2005
Member Is Offline
Mood: trying to figure out why I need a dark room retreat when I live in a forest of wattle.
|
|
when adding NaOH too KI I dont think you will get a displacement.
but the I2 you should get a mixture of NaI and NaOI
to make NaI from Iodine Tinc which is actualy NaI3 or NaI and I2 mixture you should first
drop the iodine with an oxidising agent like peroxide or ammonium persulfate (any persulfate will work
and usually gives larger and easier crystals to filter than a peroxide.)
then put the newly formed iodine in NaOH solution that is of equal molar content.
evap water then heat NaI and NaOI powder to 200 plus you will have to check the brake down point of NaI
as it will brake down at a certian temp.
this will expell the oxygen from the NaOI and make NaI.
Al in your caustic give up now.
e3500 console login: root
bash-2.05#
|
|
|
Ephoton
Hazard to Others
Posts: 463
Registered: 21-7-2005
Member Is Offline
Mood: trying to figure out why I need a dark room retreat when I live in a forest of wattle.
|
|
@ chemistry Alchemist
I would think peroxide mixed with NaOH solution would do the trick on acetone
when mixed with NaI. but then it is making the I2 insitue then and then forming sodium hypoiodide to
complete haloform reaction.
What can be done that is funky with iodoform ive never used it ?
that is other than its boiling point.
e3500 console login: root
bash-2.05#
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
