Per
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Highly concentrated H2O2 by extraction with CCl2H2
It is well known that 100% nitric acid can be extracted with CCl2H2 from dilute nitric acid and H2SO4.
So my short question is if this would also be possible with dilute H2O2, let´s say a 30% solution?
Has anybody read something about that?
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hissingnoise
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| Quote: | Originally posted by Per
Has anybody read something about that? |
Nope! If it worked I think we would have!
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crazyboy
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Never heard of that but I don't think your "well known fact" is really a fact. I recall it being extracted but then people were left with a mixture of
dichloromethane and nitric acid that fumed but was difficult to separate and equally difficult to use in nitrations.
Also there was some talk of extracting hydrogen peroxide with diethyl ether but it was deemed suicidal due to the possibility it would form dangerous
organic peroxides.
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hissingnoise
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Yes, those raffinates were a buzz on first reading of the patent---the euphoria, though, evaporated a lot quicker than the solvent.
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garage chemist
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Why should CH2Cl2 work for H2O2? The H2O2 molecule is about as polar as H2O, so I can't see any reason why H2O2 should preferentially go into the
organic phase.
The diethyl ether extraction of H2O2 is mentioned in Brauer. But this uses high-percentage raw material (over 80% IIRC) and is only useful for getting
the concentration above that when one has that.
The >80% H2O2 is stirred with a large volume of Et2O, the Et2O seperated and dried (!) and evaporated carefully.
For getting the concentration from 30% to 70%, vacuum evaporation of the water, preferrably using a column, is best. It was done in industry this way
too, in combination with the earlier peroxodisulfate hydrolysis process for H2O2 production.
The 70% H2O2 is a powerful energetic oxidiser (try putting a few drops on a burning piece of wood! 70% HClO4 has the same effect with the wood.) and
still reasonably safe.
Going above 70% with vacuum evaporation quickly becomes inefficient, since a lot of H2O2 begins to codistill with the water despite the column.
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S.C. Wack
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Well, continuing with the ether thing, it may also be possible with lower concentrations of peroxide, but unfavorable. According to Tet Lett 24, 1737
(1983), 2.5 M anhydrous H2O2 in ether is obtained by repeated extraction of standard 30% H2O2 with ether and drying with MgSO4.
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woelen
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I once tried naively with CH2Cl2 and from my experiment with 30% H2O2 I can confirm the words of garage chemist. It does not work! No H2O2 is
extracted into the CH2Cl2.
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Gruson
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Offtopic: Can someone point me to the thread / further sources on that the DCM/HNO3 method doesn't work as promised, because I can only find threads
mentioning the method itself, or vulture's experiment, which seemed to work.
It could be that the purpose of your life is only to serve as a warning to others.
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Per
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I tried it yesterday at myself, with conz. H2SO4, almost no H2O2 goes into the CH2Cl2 phase, I tried to detect it with the luminescence of an oxalic
acid ester and only a very weak light emission was visible which is a bit curious because the DCM is normally used in this chemiluminescence as
solvent and works fine, and that´s why I came to the idea that the H2O2 extraction could work.
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franklyn
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CO(NH2)2•H2O2 , Carbamide Hydrogen Peroxide Adduct , CAS - 124-43-6
Beilstein Registry Number: 3680414 , Beilstein 3, IV, 94 ,
Solvates with dissociation , in alcohol , acetone or ether.
Forms detonable shock sensitive solution with acetone, particularly with ether.
Given that urea is insoluble in either acetone or ether , this provides a
preparative method of anhydrous H2O2.
Urea Peroxide is prepared by a solution of Urea in 30% hydrogen peroxide , in the
molar ratio of 2 : 3 , it is heated in a Pyrex dish for a few minutes at about 60 ºC.
When cool it is transferred to a crystallizing dish for slow evaporation and crystallization.
Usually the crystals grow in the shape of needles.
A not much safer approach.
Glacial acetic acid forms a salt quantitatively with urea releasing the H2O2.
CO(NH2)2•H2O2 + HOOCCH3 => CO(NH2)2•HOOCCH3 + H2O2
Peracetic acid is not formed unless a stronger mineral acid is present.
see page 38
http://www.jproeng.com/qikan/manage/wenzhang/207239.pdf
________________________
It appears that :
A mixture of acetic acid with acetone can precipitate urea acetate , with acetone
buffering the enthalpy of reaction and providing the liquid phase for the H2O2.
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The WiZard is In
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Quote: Originally posted by Per  | It is well known that 100% nitric acid can be extracted with CCl2H2 from dilute nitric acid and H2SO4.
So my short question is if this would also be possible with dilute H2O2, let´s say a 30% solution?
Has anybody read something about that? |
H2O2 can be concentrated by freezing. The Devil is in the
chemical engineering. You can not do it in your home fridge.
If I hadn't put magic mushrooms of the pizza for dinner I
would try to remember where I read the details.
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Taoiseach
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@franklyn
Fascinating stuff you found there! I have ~500g of urea peroxide, gonna try that extraction ASAP.
Btw here's a method for the preparatio of UP (its in German):
http://www.chemieunterricht.de/dc2/tip/11_05-01.htm
I tried this years ago and it worked quite well.
[Edited on 30-4-2010 by Taoiseach]
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The WiZard is In
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In da US of A it be called UHP or solid hydrogen peroxide.
Noted in passing — commercial H2O2 is usually shipped at 70%. (264 volume.)
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franklyn
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| Quote: Originally posted by The WiZard is In | H2O2 can be concentrated by freezing. The Devil is in the
chemical engineering. You can not do it in your home fridge.
If I hadn't put magic mushrooms of the pizza for dinner I
would try to remember where I read the details. |
Major thread with my informational post
http://www.sciencemadness.org/talk/viewthread.php?tid=1325&a...
From Percarbonate
http://www.sciencemadness.org/talk/viewthread.php?tid=971#pi...
H2O2 concentration by freezing GB889421
H2O2 concentration by freezing US2724640
The definitive paper to freeze fractioning
Anhydrous Hydrogen Peroxide as a Propellant _ R. Bloom , N.J.Brunsvold
Chemical Engineering Progress ( 1957 ) 53 (11) p.541-7
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Ephoton
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I actualy think it might work though in very small amounts of peroxide to DCM
think of a peracetic acid reaction. peroxides have to be soluble to an extent or the synthesis
would not work. understandably there is an organic acid attached to this but most of this
is the salt of an organic acid so some ionics have to be playing part in the equalibrium of DCM's
solvated mix.
I think that it probably is not used or spoken about becouse only a small amount of peroxide would
be disolved in the DCM so it is realy not worth the effort.
but then again continuouse extraction might make a difference
DCM does disolve some water.
e3500 console login: root
bash-2.05#
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