GhostofUnintentionalChaos
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Dehydrating Copper Nitrate
This is UnintentionalChaos. I tried to log on with a different computer and I couldn't remember the password, so I requested it to my e-mail, but I'm
impatient and its taking a while, so I made another name temporarily.
Is it possible to dehydrate Cu(NO3)2 *2.5H2O (or *3H2O) without it decomposing or subliming, both of which occur at very low temperatures. Also, info
on the compound seems to be scarce. Does anyone know just how soluble it is in alcohol? I may have to rethink my synth if it's not as soluble as I'd
hoped.
Thanks,
UnintentionalChaos
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not_important
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The only possibility that I know of is to react it with N2O5, which reacts with the water forming nitric acid.
The hydrated forms of cupric nitrate are reasonably soluble in alcohol, no idea on the anhydrous.
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woelen
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Making anhydrous copper (II) nitrate is very difficult. This has eluded chemists till the sixties of the past century. It finally succeeded by
dissolving copper in liquid NO2, in which some N2O5 was dissolved. The NO2 was diluted with some solvent (IIRC it was CH2Cl2) in order to make the
reaction less vigorous. On evaporation of the solvent, the NO2 and N2O5 at reduced pressure, a solvated solid remains, Cu(NO3)2.xNO2 (I don't remember
x anymore, I think it is 2). On careful heating of this solid (at 80 C or so), the NO2 slowly is given off and anhydrous copper (II) nitrate remains.
Anhydrous copper (II) nitrate is not a salt, but a volatile covalent compound.
Careful heating of Cu(NO3)2.3H2O leads to loss of both water and nitric acid and at best a basic copper nitrate is formed, something like Cu(OH)(NO3),
but the ratio of OH(-) and NO3(-) may be different than I suggest with this formula. Stronger heating of Cu(NO3)2.3H2O leads to loss of all nitric
acid in the form of acid, NO2 and O2. What remains is CuO.
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chemoleo
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And superstrong dehydrating agents won't do the job? I wonder what will happen in i.e. the presence of absolute ethanol/acetone etc, or an active
scavenger such as acetanhydride or trifluoro acetanhydride...
+
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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woelen
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Probably it will loose (some of) the water, but then you don't have it isolated. Probably that has been the lergest problem for preparing the
anhydrous compound. Isolation probably leads to decomposition.
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GhostofUnintentionalChaos
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I wonder if the water of hydration become remotely dissociated in alcohol solution. An insoluble dehydrating agent (MgSO4) could be stirred in,
filtered out, and the alcohol evaporated off, leaving *hopefully* drier copper nitrate. To go ina completely different direction, does anyone know if
tetraammine copper nitrate is alcohol soluble? I was thinking bubble dry ammonia gas through the alcohol solution to ppt the now explosive compound.
This is heading quickly toward energetics...I'd rather not break up the thread though.
[Edited on 19-2-2007 by GhostofUnintentionalChaos]
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AndersHoveland
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If you are trying to make real anhydrous Cu(NO3)2, you can probably forget ethanol. Anhydrous Cu(NO3)2 is a reactive nitrating agent. I think the
anhydrous form is difficult to prepare, and cannot be made by simply heating the hydrate, as the thermal decomposition results in other products.
"at temperatures below –5°, the reaction of diethyl ether with copper(II) nitrate yields exclusively gaseous ethyl nitrite and complexed
acetaldehyde. At higher temperatures, the acetaldehyde is further oxidised to acetate, with liberation of gaseous NO and NO2"
Anhydrous copper(II) nitrate as an oxidising agent. L. C. Coard and R. E. Powell
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Vargouille
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I believe that tetraaminecopper (II) nitrate is insoluble in alcohols. The sulfate monohydrate is, and I believe that I recall a mention that while
most tetraaminecopper (II) salts are mostly insoluble in alcohols, Schweizer's reagent reacts with alcohols. There is also this thread.
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AndersHoveland
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I really do not think this is correct. If you read the synthesis for TACC, it shows that both copper(II) chlorate, and TACC are soluble in methanol.
The TACC does not begin crystallizing out until the methanol begins to evaporate. Nitrates tend to be more solube than chlorate salts, btw.
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