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Felab
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Easy synthesis of hydroiodic acid
Hi! I´m in need of some hydroiodic acid not because I wanna make meth but to synthesise lithium, cadmium and amonium iodide (for photographic use).
All the synthesis that where provided by the silver sunbeam book where either out of my reach or extremely dangerous.
This morning, I was thinking about a way to synthesise it and I camed up with an idea: reducing elemental iodine by the means of ascorbic acid. Sure
enough, I tried ading some ascorbic acid to iodine in a beaker and the solution turned deep red at first but then it cleared up as the ascorbic acid
had time to work. The final solution was a very faintly yellow liquid (almost colorless) with a hidrochloric acid like odor (although slightly
different).
Now, should I try this at a larger scale? Am I generating hydroiodic acid or some other weird complex? Is there any other method to produce hydriodic
acid without dangerous or dificcult to get chemicals?
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Tsjerk
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Maybe reduce with sodium dithionite and seperate NaI by crystalization of sodium sulfate, followed by acidifying with sodium hydrogen sulfate or
sulfuric acid, (another crystallization of sodium sulfate in the case of sodium hydrogen sulfate) and then distillation?
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Felab
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I already have potassium iodide and the problem is that the sulphuric acid oxidises it. I- is very easily oxidised.
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Tsjerk
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Then what about phosphoric acid?
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wg48temp9
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Quote: Originally posted by Felab  | | I already have potassium iodide and the problem is that the sulphuric acid oxidises it. I- is very easily oxidised. |
What precisely do you need the iodide for that potassium iodide will not work?
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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Felab
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The problem is that potassium iodide is almost insoluble in absolute ethanol and ether. Also, collodion made with it is quite unsensitive to light.
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Felab
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It's what's normaly used but I don't have any. I could buy but only by the liter so I want an alternative with chemicals that I already own.
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draculic acid69
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HI from h3po4 requires 300+'c to achieve any result.
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WGTR
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Since you want to make ammonium iodide anyway, if you can source (or make) some ammonium phosphate (fertilizer), you may be able to sublimate ammonium
iodide by heating a mixture of the phosphate and potassium iodide. There would probably be some loss of ammonia from this, with the resulting
production of some HI directly. You could also use ammonium sulfate, but as you mentioned before, may end up oxidizing the iodide somewhat.
Attachment: chaiken1962.pdf (726kB)
This file has been downloaded 523 times
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Felab
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| Quote: Originally posted by WGTR | Since you want to make ammonium iodide anyway, if you can source (or make) some ammonium phosphate (fertilizer), you may be able to sublimate ammonium
iodide by heating a mixture of the phosphate and potassium iodide. There would probably be some loss of ammonia from this, with the resulting
production of some HI directly. You could also use ammonium sulfate, but as you mentioned before, may end up oxidizing the iodide somewhat.
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The thing is that ammonium iodide yields a very sensitive to light collodion, but very unstable, decaing only in a few weaks. To arrest this effect,
cadmium iodide is usualy added, but the cadmium iodide is an extremely water soluble cadmium salt, so therefore it is very toxic. Also, you need
hydroiodic to make it. I would prefer to make lithium iodide and bromide, which yields a very good, almost non toxic collodion.
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AJKOER
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My old prior thread on the prep of HI may be of interest at http://www.sciencemadness.org/talk/viewthread.php?tid=18302&... .
Especially:
| Quote: Originally posted by simba | | Quote: Originally posted by blogfast25 |
Same with the 'bisulphite method': if it was that easy we'd be using it NOW. Often these ideas work only on paper and for very weak solutions...
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Indeed, it sounds too good to be true. I don't know if it is a good method for producing HI because I haven't tried it, but it does generate HI
afterall.
I2 + NaHSO3 + H2O → 2 HI + NaHSO4 |
where sulfite salts are available from home brewing sites.
-------------------------------------------------------------------
A path to test (see Patent https://patents.google.com/patent/US5520793A/en ) would be via the action of the reducing hydrogen atom radical. For example, with I2 and H2O, I
would describe the system by the reactions:
I2 + H2O = H+ + I- + HOI
HOI + .H = H2O + .I (pH acidic dependent products)
.I + .I = I2
........(other products)
where, for example, a path to the hydrogen atom radical is:
H+ + e- = .H
and the e- is sourced from electrolysis per patent above.
Interestingly, one could apply the same argument to the so called 'bleach battery' employing Aluminum metal and HOCl (from weakly acidified bleach)
where the products are Cl2 and H2O:
Al --> Al3+ + 3 e-
e- + H+ = .H
HOCl + .H = H2O + .Cl (non-alkaline conditions, see note below)
.Cl + .Cl = Cl2
...
where the e- are sourced in an electrochemical (or battery) cell and not from an external source of electricity as above.
Note, a more accurate radical path is likely:
HOCl + e- = .ClOH- (see Table 1.2a: Chlorine at https://www.bnl.gov/isd/documents/92710.pdf and Supplement Table S1, link below, Reaction [1], and [116] for Iodine)
.ClOH- + H+ = H2O + .Cl (pH < 5, k = 2.1×10^10 Source: Supplement Table S1 at: http://www.mdpi.com/1420-3049/22/10/1684 and click on Supplement F1 to download)
[Edited on 2-1-2019 by AJKOER]
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Felab
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The bisulfite method might work but in a very diluted solution because hydroiodic acid converts the bisulfite into sulfurous acid, which imediatly
disproporcionates into water and sulfur dioxide, consuming the reagent and stopping the wanted reacction.
HI + NaHSO3 = NaI + H2SO3
H2SO3 = H2O + SO2(g)
If you get a yield of hydroiodic acid it will probably be terrible.
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AJKOER
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I view the reaction more like:
I2 + H2O = H+ + I- + HOI
HOI + HSO3- = H+ + I- + HSO4-
------------------------------------------------------
Net: I2 + H2O + HSO3- = 2 H+ + 2 I- + HSO4-
The actual reaction is more complex, as I have ignore the disproportionation reaction of HOI to HIO3. To quote a reference:
"Under acidic conditions Iodate reacts with Iodide to make Iodine, then immediately the Iodine reacts with the Sodium Sulfite until there is no more
Sodium Sulfite. Then the Iodine reacts with the water and the Soluble Starch and that is what forms the blue complex."
Link: http://cssf.usc.edu/History/2002/Projects/J0512.pdf
[Edited on 2-1-2019 by AJKOER]
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Ogannessionn
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H2 + I2 = HI
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Felab
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* H2 + I2 = 2HI*
I would't try having a controled hydrogen fire.
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lordcookies24
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then I would use phosphoric acid
edit: I said something dumb that is wrong
[Edited on 3-1-2019 by lordcookies24]
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clearly_not_atara
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| Quote: Originally posted by Felab | | [Phosphoric acid is] what's normaly used but I don't have any. I could buy but only by the liter so I want an alternative with chemicals that I
already own. |
Well, if you don't mind doing extra work,
- you can make some p-toluenesulfonic acid by heating sulfuric acid and toluene. That will liberate HI without any oxidation.
- Alternatively if magnesium sulfate (Epsom salt) is available you may be able to perform some salt metathesis with potassium iodide, precipitating
K2SO4, then boil down aqueous MgI2 which will eventually liberate HI. This method will have a poor yield, but it should give you some.
- Or if ammonium phosphate is available you can simply heat it to drive off ammonia and leave behind phosphoric acid. Beware of a very bad smell. It
is present in fire extinguishers but usually as a mixture with the sulfate.
- If sulfamic acid (rust remover) is available, that might work.
- If zinc is available, you can try Zn + I2 >> ZnI2, and then dry distillation of the hydrate should liberate HI to leave behind a
hydroxyiodide.
Overall I'd buy a liter of H3PO4. Sounds much easier than any of this crap.
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Felab
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I think I will try the ascorbic acid methode.
Also, I want high yeld since I don't have a lot of iodine.
If I wanted to make more than 40 ml I would probably buy the phosphoric acid, but photographic applications don't require much iodide.
[Edited on 4-1-2019 by Felab]
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Boffis
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What is wrong with the traditional method of using Hydrogen sulphide and iodine. The hydrogen sulphide can be generated from iron sulphide by the
usual process and passed into a suspension of iodine in water. Providing the rate of hydrogen sulphide generation is not too rapid and an inverted
funnel is used to do the gassing then practically not H2S escapes until almost all of the iodine has gone. The milky suspension is then boiled to
expel any excess H2S and also to coagulate the sulphur, to make it easier to filter, and cooled. The solution is normally filtered and then distilled
but you could probably just filter it to remove the sulphur.
This process is described in detail somewhere though I can't remember exactly where, try Brauer though (SM library)
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Sulaiman
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Just had a read ... pp288 Brauer (good memory Boffis!)
I would like a little HI(aq) and I have diy FeS so I could follow this procedure ...
what is the benefit the over the phosphoric acid route ?
(which is mentioned under regeneration of HI(aq))
CAUTION : Hobby Chemist, not Professional or even Amateur
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AJKOER
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The marginal difference in efficiency of the reactions:
HOI + HSO3- = H+ + I- + HSO4-
HOI + H2S = H+ + I- + H2O + S
does not warrant, especially in a home lab setting, of employing H2S over H2SO3 (aqueous SO2)!
Some possible scenarios when using H2S:
1. Your home (and you) smells like rotten eggs, and you hope nobody notices.
2. You dump the residue H2S rich solution and it flows into your neighbor's yard, who then calls the county to investigate a sewage leak.
3. You have investigators knocking on your door and the first point applies.
4. Law enforcement arrives and there don't even bother to knock....
5. H2S is quite toxic (see https://www.ncbi.nlm.nih.gov/books/NBK208170/ ), in the range of 10 to 20 times the lethal dose of HCN (see https://www.cdc.gov/niosh/idlh/74908.html )!
6. At higher exposure levels (which includes both inhalation and possible skin exposure, see http://www.sciencemadness.org/talk/viewthread.php?tid=10491&... ), you may no longer be even able to smell it (making it more deadly), but others
can and you are unaware of the ongoing danger!
7. Because you are still apparently alive, does not mean you have NOT received a fatal dose (a case of the walking dead, with eventual organ failure
progressing)!
8. For those poisoned and surviving, here is an interesting abstract (fom https://www.ncbi.nlm.nih.gov/pubmed/1772008 ):
"A shipyard worker was poisoned by hydrogen sulfide (H2S), and rescued after 15-20 min. He regained consciousness after 2 days. Three days later his
condition deteriorated, and he was more or less comatose for a month. When he woke up, he was amnesic, nearly blind, had reduced hearing, and had a
moderate spastic tetraparesis and ataxia. Two months after the accident, he had greatly improved. Audiograms showed hearing loss with maximum at 2000
Hz and significantly poorer speech discrimination. EEG showed generalized dysrhythmia. At follow-up 5 years later he had not been able to resume his
work, and had slight motor, memory and visual symptoms. CT and MRI showed slight cerebral atrophy. EEG and evoked responses were normal."
While with SO2:
1. A transient smell due to some home brewing, your new legal hobby.
[Edited on 7-1-2019 by AJKOER]
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Felab
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| Quote: Originally posted by Sulaiman | Just had a read ... pp288 Brauer (good memory Boffis!)
I would like a little HI(aq) and I have diy FeS so I could follow this procedure ...
what is the benefit the over the phosphoric acid route ?
(which is mentioned under regeneration of HI(aq)) |
The silver sunbeam details this procedure but I only want to try it as a last resource because H2S is a pain to work with and it is also incredibly
toxic.
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Felab
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Ascorbic acid methode went wrong
This morning I went to try the ascorbic acid methode I described.
Everithing was going well: a slightly yellow liquid came over and got redder and redder as the distilation proceeded.
When I stopped the distilation I smelled the liquid and it smelled like toluene? I was stuned by that and then I tested acidity and it wasn't acidic .
I have no idea of what this thing is.
If someone has, please tell me.
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Boffis
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@Ajoker, I have used hydrogen sulphide as a reducing agent many time because it is so easily handled and the byproduct so easily removed. If you
cannot use it safely then I think its time you moved to stamp collecting or a similar hobby.
The separation of HI from sulphuric acid is not easy as at higher temperatures the reaction goes in the opposite direction and you get your SO2 and I2
back. You could of course selectively precipitate the sulphuric acid by partial neutralization with barium hydroxide but if you can't engineer a
simple and safe set up to handle H2S then the partial neutralization is probably beyond you too.
Clearly ascorbic acid is not a great route either.
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clearly_not_atara
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HI reacts with ascorbic acid to make iodoalkanes. That's probably what you smelled.
I do not recommend working with H2S as, based on your other posts here, you are not skilled enough to handle a substance with an LC50 below 1000 ppm.
Inappropriate technique or poor confinement when generating H2S may cause a severe health hazard to both you and your neighbors.
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