tsathoggua1
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HICl2 / HCl2I dichloroiodic acid
I've just read something interesting, doing some research on interhalogens prior to attempting synthesis of bromine chlorides and iodine bromides.
(one other question-are any interhalogens known containing I, Cl and Br? and are bromine tri or pentahalides absent fluorine known at all? I am
omitting the fluorinated interhalogens from my poking about with this interesting category of compounds. So far, I have successfully synthesized
somewhat over an oz of ICl, and purified it via distillation. all I've done are tests of oxidizing power with various fuels and ignition (unconfined,
since I do not want any explosion potential) and testing on a few tens of mg of fuels and drop scales of ICl. Also some ICl3 remaining in the still
flask that I will purify after running some excess Cl2 through the system. It was prepared by packing a liebig with iodine, and connecting it to a
chlorine generator with a dessicant (CaCl2) in between the generator and the iodine. The vapors were collected and the product was distilled
successfully at atmospheric pressure.
Reportedly, upon treatment with anhydrous hydrogen chloride, a strong hydrohalic acid, dichloroiodic acid, HICl2 or HCl2I is formed, by the action of
the hydrogen halide upon ICl. Do other hydrogen halides, such as hydrogen bromide or HI form HBr2I, or HI3? again, not going to be attempting to
prepare mixed hydrofluoric type hydropolyhalic acids.
Do these have oxyacid derivatives such as perdichloroiodic acid, dichloroiodous/dichlorohypoiodous acids etc? reportedly HCl2I is quite a strong acid.
Anybody ever tried preparing either it, oxyacid derivatives, perhaps by reacting perchloric acid and ICl, hypochlorous acid, hypoiodous acid,
hypobromous acid solutions in a polar, aprotic solvent such as acetonitrile?
Are such acids stable at RT? vapor phase? can they be distilled at atmospheric pressure or under vacuum? I see no reference whatsoever in TFSE to this
acid or others like it. What are the simple group I/II metal salts like with regards to stability? and anybody prepared this or similar hydropolyhalic
acids?
Any ideas for what might be done with it/them? As of yet, I haven't had time to prepare the dichloroiodic acid, but I might give it, or
dichlorobromic, diiodobromic dibromoiodic acids from the respective hydroge halides and interhalogens tonight if I get the urge to start tinkering as
I so often do. IBr and BrCl might be on the to do list as well, now my NaBr has arrived.
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AJKOER
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Assuming HICl2 is as claimed a strong acid:
HICl2 = H+ + ICl2-
The last species could be similar to the well known:
Cl3- = Cl- + Cl2
which implies to me:
ICl2- = Cl- + ICl
To possibly prepare HICl2, add ICl to HCl, so not too mysterious, a path which you did mention.
[Edited on 9-6-2017 by AJKOER]
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tsathoggua1
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Yes, already read that HICl2 can be prepared by treating ICl with anhydrous HCl gas (ICl is non-pyrophoric, but is reactive with H2O and other protic
compounds, in the case of H2O it dissociates into free Cl2 and I2. To say it is prone to hydrolysis is somewhat of an understatement. Addition of 1
drop of freshly distilled iodine mobochloride, cooled down, after taking the bottle from the fridge in which it is kept in order to keep the vapor
pressure as low as possible, and coupled with the inert polymer capped/sealed bottle and a little teflon tape round the screw threads manages to keep
it from escaping; to a container of cold H2O, results in nearly instantaneous decomposition to the free halogens in a puff of Cl2 gas and finely
divided iodine dropping through the water.
Haven't yet gotten to attempting the synthesis of dichloroiodic acid (will try in something fairly inert and suitable for such halogen-like species
such as CH2Cl2 when I do. I've other things on my mind atm such as synthesis of the iodine and bromine chlorides, and iodine bromides.
Was wondering if analogous reactions using a hydrohalic acid and other diatomic interhalogens take place to form similar acids of the general formula
H1Xn2-X where 1X=two halogen atoms of the same element and X=single atom of another of the halogen species.
And also, what practical synthetic use/s HCl2I might have, and properties if well known. There doesn't seem to be a great deal regarding this novel
hydropolyhalic acid online that I've found, and according to TFSE this is the first thread here on it. And there is surprisingly little on the
interhalogens themselves, for such interesting yet accessible chemistry.
Are any corresponding oxyacids known? such as would lead to polyhalide analogs to chlorates or perchlorates, periodates etc?
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clearly_not_atara
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Acidic solutions containing the BrCl2- ion can be made by adding equal parts bromate and bromide to hydrochloric acid. The solutions are brominating
agents. However HBrCl2 does not appear to be stable.
I'd be impressed if someone could crystallize a salt of BrCl2 such as trimethylanilinium or hexamminecobalt. It doesn't sound easy but it might be
possible.
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