UnintentionalChaos
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Lewis Acids
I do not know as much as I would like about lewis acids, so here is my question. Would either ZnCl2 or AlCl3 undergo any reaction with
ethanol/methanol mix under standard conditions? Probably a stupid question, but I don't know too much about lewis acid reactions and I know AlCl3 is a
very powerful one. There would also be a small amount of metal powder present.
I'm actually looking at a simple method of generating anhydrous AlCl3 and ultrafine Zn powder at the same time. The idea is this:
CuSO4 (aq) + CaCl2 (aq) -> CuCl2 (aq) + CaSO4 (s)
This takes advantage of the fact that aqueous CuCl2 can be dried to anhydrous easily, and with an extremely small amount of oxychloride formed, if any
appreciable amount. It is impossible to dry aqueous zinc chloride or aluminum chloride without hydrolysis occuring.
From now on, reactions occur in denatured alcohol, that has been dried (although I find that straight from the can, it has virtually no water in it
anyway).
CuCl2 + Zn -> ZnCl2 + Cu (filter through glasswool or you'll dissolve the cellulose with the ZnCl2)
I have no idea with what you could do with copper that fine, but there must be some use.
3ZnCl2 + 2Al -> 3Zn + 2AlCl3 (I imagine a glasswool filter would be useful here too)
The best part of this is that the AlCl3 prodced will be exceedingly pure, even if you use aluminum foil. The key is to use an excess of metal in each
step and allow to go to completion in a tightly sealed container (keep water out) The main impurities in Al foil are iron and silica. The iron will
not replace the Zn and along with the insoluble silica, fall into the ppt Zn powder, which will be plently pure enough for any pyro uses you may
desire and probably just fine for chemistry. The alcohol should then be evaporated off under vacuum, if possible.
For anyone attempting this, a brief warning. Strong ZnCl2 solution can and will eat holes in your clothing if you let it. Anhydrous AlCl3 has an
enormous heat of hydration and is very hygroscopic. Allowing the anhydrous salt to contact water may cause an "explosion" as the water rapidly boils
and sprays salt everywhere, if not done under controlled conditions. I believe one of our members had an incident like this and could verify my
warning.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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12AX7
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Dunno if ZnCl2 + Al > AlCl3 + Zn works...might not in alcohol or whatever, and obviously though it works in H2O, they also form tenacious hydrato
complexes.
Tim
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UnintentionalChaos
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I'm absolutely sure that an alcohol solution of CuCl2 can eat through steel, so I don't see what would stop aluminum from displacing zinc. It is
possible that there was a small amount (very small) of water in that mixture, however. I'll have to give it a shot.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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The_Davster
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If the rxn goes as hoped any AlCl3 is going to rip off the alcohol proton forming HCl and Al(OCH2CH3)3, aluminum ethoxide. Lots of anhydrous metal
chlorides do this, I have made a whole bunch of the tungsten ones. You need a solvent that is lacking such a negative centre(lewis base character).
Even THF would complex I think.
Not sure if zinc chloride or copper chloride are hard enough acids to do the same thing as aluminum, but I doubt it.
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Ozone
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Interesting:
Opening of the tetrahydrofuran ring under the action of aluminum halides
Journal Russian Chemical Bulletin
Publisher Springer New York
ISSN 1066-5285 (Print) 1573-9171 (Online)
Subject Chemistry and Materials Science and Russian Library of Science
Issue Volume 5, Number 6 / June, 1956
Category Brief Communications
DOI 10.1007/BF01178944
Pages 761-762
SpringerLink Date Wednesday, February 09, 2005
Apparently, AlCl3 can open the ring leading to dichloro-products (AlBr3 is similarly effective). The most serious Lewis acid I have used is SbCl5, and
it perchlorinates just about anything, viz. biphenyl-decachlorobiphenyl.
Zn and CuCl2 are not going to do this under normal conditions, viz. STP.
Cheers,
O3
Olde Skule!
Received: 24 March 1956
Summary
1. It was shown that the tetrahydrofuran ring is opened under the action of aluminum chloride or bromide with formation of dihalo paraffins.
2. It was found that reaction of tetrahydrofuran with aluminum chloride gives 1,4-dichlorobutane in 32% yield, and reaction of
tetrahydro-2-methylfuran with aluminum chloride and with aluminum bromide gives, respectively, 1,4-dichlcfopentane in 58% yield and 1,4-dibromopentane
in 67% yield.
[the summary is a cut-paste; the spelling errors were indigenous]
[Edited on 27-1-2007 by Ozone]
[Edited on 27-1-2007 by Ozone]
[Edited on 27-1-2007 by Ozone]
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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Ozone
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Is not chromium trioxide:H2SO4 a strong *oxidizer*, aka. Jone's reagent, Chromic acid, etc. Without modification this reagent goes all-the-way, viz.
R-OH --> R-O --> R-OOH.
O3
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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