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Author: Subject: Copper(II) Ethoxide Synthesis
ManBearSwine
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[*] posted on 27-1-2012 at 19:21
Copper(II) Ethoxide Synthesis


So, I'm planning on synthesizing some copper ethoxide through the electrolysis of ethanol with a dissolved copper salt. The reaction is fairly straightforward with Curpic Chloride:
2 C2H5OH + 2Cl(-) + Cu(+2) ---> Cu(C2H5O)2 + H2 + Cl2
However, I'd prefer not to have to deal with the chlorine, so I'm thinking about using Copper(II) Acetate, which is where I'm stuck... As far as I can figure it, either acetate will be oxidized to methyl acetate and carbon dioxide or the copper electrode will be oxidized and the acetate will not react. Or both. Any insight on this one?
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[*] posted on 29-1-2012 at 16:34


Do you have some idea on how stable copper ethoxide is?
Is this a known procedure or have you just made it up off your own bat?
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ManBearSwine
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[*] posted on 29-1-2012 at 22:14


It hydrolyses upon contact with water or moist air and decomposes when heated over 120 Celsius.
I've yet to see this process described anywhere, but considering as it can be used to produce sodium ethoxide, I don't see why it wouldn't work for copper.
I've done some more research and I've found that the electrolytic oxidation of acetate forms carbon dioxide and two methyl radicals, which then combine to form ethane. So, the overall reaction should be:
2 C2H5OH + Cu(2+) + 2 CH3COO(-) ---> Cu(C2H5O)2 + H2 + CO2 + C2H6
Now I just need to make some anhydrous copper acetate, which I failed at yesterday. I think I need something gentler than a blue hot flame.
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AJKOER
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[*] posted on 3-2-2012 at 11:20


Quote: Originally posted by ManBearSwine  
It hydrolyses upon contact with water or moist air and decomposes when heated over 120 Celsius......

Now I just need to make some anhydrous copper acetate, which I failed at yesterday. I think I need something gentler than a blue hot flame.


Be careful if you reaction calls for anhydrous Ethanol as well as it is very expensive and you may most likely just have the 95% alcohol / 5% water solution.

Also, have you considered working with CuSO4 (the anhydrous form is a pale green or gray-white powder)?

[Edited on 3-2-2012 by AJKOER]
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[*] posted on 3-2-2012 at 12:20


Its not soluble in ethanol, IIRC.



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BromicAcid
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[*] posted on 3-2-2012 at 12:31


Electrolysis of the acetate would give nice side reactions, look up Kolbe Electrolysis.



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Lithium
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[*] posted on 25-2-2012 at 21:45
Copper ethoxide ?


hello i am new to this forum but have been fascinated by all of it's posts and threads.

i am also thirteen, so excuse me if i miss something obvious.

a year or 2 ago i made some electrolytic copper dust from the electrolysis of copper sulfate with copper electrodes. i had stored it under methylated spirits ( 96% ethanol) for ages and forgot about it.

today i pulled it out and noticed a 1cm layer of a blue crystalline compound on top. when mixed with water it bubbles. the Cu dust may actually Cu2O because they look quite similar.

any thoughts?

Lithium:D
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weiming1998
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[*] posted on 26-2-2012 at 01:40


Have you washed your copper dust properly? Because that might be some leftover copper sulfate.

Copper ethoxide cannot form by copper and ethanol or Cu2O/ethanol. Ethanol is not an oxidizing acid (it is barely an acid at all!), so it cannot react with elemental copper metal. Even if the copper dust is oxidized to Cu2O and reacted, the formation of water will decompose the copper ethoxide, forming ethanol and Cu(OH)2, which might be an alternative explanation to the blue layer. But I highly doubt it; H2O is a stronger acid than ethanol, which is why copper ethoxide decomposes in water in the first place.
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Lithium
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[*] posted on 26-2-2012 at 02:06


Thanks!

you are first to reply to my question, you win a teddy bear!

it was washed 3-4 times minimum,with water and etOH, i thought there was something a bit wrong with this.

though that still doesn't explain why it bubbles on contact with H2O, could it be reacting with a denaturant in the metho perhaps?

Li
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Nicodem
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26-2-2012 at 03:17
weiming1998
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[*] posted on 26-2-2012 at 03:49


That bubbling on contact with water is difficult to explain; even copper ethoxide itself doesn't bubble in water; there are no gaseous products formed! Pyridine and methanol, the two most common denaturants, does not react with water. I think that there are two explanations for this:

Either the dry blue substance (which might be Cu(OH)2) was filled up with air, and then the air bubbled out when it was absorbing moisture in the water, or some sort of copper-pyridine complex was formed that reacted with the water (that requires the copper to be Cu2O, as I don't think pyridine does anything to elemental copper).

Which leads to another question; have you collected some of the substance? If you did, then you might do some tests to determine what it is.

[Edited on 26-2-2012 by weiming1998]
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Lithium
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[*] posted on 26-2-2012 at 11:56


in an attempt to extract the crystals, the copper powder was mixed in also. i managed to salvage some, so i ran some tests:

compound was mixed with ethanol and burnt, no visible decomp. was observed, and it turned from anhydrous (white) back to blue after some time, so it's stable at high temp.

HAHAHAHAHA

oh geez, it doesn't bubble on contact with water, i thought my beaker of 4-amino 1-hydroxy phenol hydrochloride with excess HCl acid was water!:o lucky i don't drink in the lab!:D

the Cu dust now smells horrid, and i was almost sick after getting a good whiff of it.

the Cu probably was oxidised to Cu2O, then that was in equilibrium as small amounts of Cu ethoxide, which was hydrolysed back into ethanol and Cu(OH)2, which fell out as crystals , so the equilibrium was slightly on the right side.

it's probably Cu(OH)2 because on trying to dissolve in water and filtration, they turned brown/black on standing, meaning it"s been oxidized to CuO.

what"s a good test for a pyridine complex?

Li
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smaerd
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[*] posted on 26-2-2012 at 13:56


I have a hard time believing you synthesized Copper II Ethoxide given the reaction conditions presented. The literature presents that Cu(II)Cl is reactive with lithium alkoxides, not ethanol alone. @ OP
Ref:
Synthesis and characterization of some Alkoxide Derivatives of Copper(II)
J. V. Singh,B. P. Baranwal,Prof. R. C. Mehrotra
DOI: 10.1002/zaac.19814770633

@Lithium
There is literature stating copper methoxide can be formed via cupric acetate in methanol in an autoclave at 110*C for three days. The article also mentions that this is a very finicky reaction(slight excess of cupric acetate yields a brown/black compound) and without heat under inert atmosphere for 11 days yields no detectable product. Water, and air readily destroy copper alkoxides iirc.

Copper(II) methoxide: direct solventothermal synthesis and X-ray crystal structure
Kendric J. Nelson a, Ilia A. Guzei b, Gregory S. Lund a, Robert W. McGaff a,
http://dx.doi.org/10.1016/S0277-5387(02)01132-4

So the notion that ethanol(probably wet) and copper (II) oxide stored in a bottle under oxygenated atmosphere, will make this compound seems unrealistic(As other people have stated).

What you made is anyones guess especially considering the error and amount of uncertainty stated in your last post.




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Lithium
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[*] posted on 26-2-2012 at 21:40


ah well, it was just an idea of what the compound might be, only because Cu ( or Cu2O )and EtOH are the main chemicals present.

i genuinely have no idea what this compound is, and if it was copper II ethoxide it would have decomposed by now, so im leaning towards the idea that it is Cu(OH)2, which was stated by weiming1998, though it could be some random thing not even cosidered yet. i should have taken a picture of it before i destroyed the layer of blue ppt.

yes, my last post was a bit wierd, sorry about that:)

Li

[Edited on 27-2-2012 by Lithium]
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weiming1998
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[*] posted on 27-2-2012 at 03:28


If it turned white when heated, then back to blue in a natural environment, then the blue substance must be CuSO4. Cu(OH)2 turns into black CuO when heated, and does not turn back into Cu(OH)2
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[*] posted on 27-2-2012 at 21:24


:o, but the salt only formed after a while in storage.

Li
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