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Author: Subject: Electrolysis of alkali salts at STP
Zyklon-A
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[*] posted on 4-3-2014 at 09:11
Electrolysis of alkali salts at STP


In this book, (on page 53) a process is mentioned were lithium chloride is electrolyzed at room temperature, dissolved in an organic solvent, like acetone or pyridine. Such a procedure is also mentioned in the unconventional sodium topic.
Of course the acetone (I don't have any pyridine) will need to be dried, this method will do.

Anyway, has anyone ever tried this? It seems like it could be the easiest method possible. Well... maybe it's tied with versuchschemie method for potassium.;)
Either way, I would like to try it, does anyone have any information that would be helpful? And does anyone know weather or not it would work with other cations, like sodium?
[EDIT, changed subject]

[Edited on 5-3-2014 by Zyklonb]




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[*] posted on 4-3-2014 at 10:18


Note that in the experiment, amyl alcohol (not easy to find) was recommended, and the lithium was actually reacting with the alcohol - just slower than it was being plated out.



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[*] posted on 4-3-2014 at 11:28


Yes, apparently lithium reacts with acetone too, albeit, very slowly.
This too mentioned Li with acetone.
But, my question remains, Can this be done with sodium? And if not, Why?




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[*] posted on 4-3-2014 at 11:45


It's not nearly as soluble as lithium chloride, apparently.
Try propylene carbonate. Fairly easy to make, all things considered.




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[*] posted on 4-3-2014 at 13:10


I'm sceptical: if a I has a penny for each prescribed 'easy', room temperature method for the preparation of Li metal I'd have quite a bit of beer money.

At a minimum, try and dig up the references of that section of the paper, before trying anything...

Wiki offers this link:

http://link.springer.com/article/10.1007%2FBF00608791

[Edited on 4-3-2014 by blogfast25]




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[*] posted on 4-3-2014 at 16:07


its probably worth mentioning than LiCl or other lithium compounds should be able to be electrolised in propylene carbonate, and that the Li might not react since propylene carbonate is an aprotic solvent. I posted an attempted synth of this somewhere in the organic chemistry section.



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[*] posted on 4-3-2014 at 19:35


Quote: Originally posted by elementcollector1  
Fairly easy to make, all things considered.


It's harder than you think (urea + propylene glycol gives ~9% yield, which must be separated out of a tarry mess.) It might work better on larger scales, though.




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[*] posted on 4-3-2014 at 19:55


Adding a catalyst of ZnO is supposed to give 98% yield...



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[*] posted on 5-3-2014 at 04:32


Quote: Originally posted by elementcollector1  
Adding a catalyst of ZnO is supposed to give 98% yield...


You have a reference for this synthesis and catalysis?




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[*] posted on 5-3-2014 at 04:35


Quote: Originally posted by Zyklonb  
But, my question remains, Can this be done with sodium? And if not, Why?


As elementcollector1 said, the solubility of the sodium salts in non-aqueous medium is significantly worse than the lithium salts severely limiting the number of non-aqueous options you have to work with. The classic example is the electrolysis in nitrobenzene which is often quoted but the whole procedure is misunderstood. It is not simply an electrolysis in nitrobenzene but you must fuse sodium chloride and anhydrous ammonium chloride to get a complex salt to perform the electrolysis, from there the material deposited at the anode is said to be explosive. Again, simple enough in theory but dastardly difficult in practice.

With regards to the preparation of propylene carbonate from urea and propylene glycol, that is another mess waiting to happen. I have not seen (but would be glad to be shown) anyone get anywhere near the yields claimed in the patent in actual practice. My own experience with producing ethylene carbonate by the urea/diol/ZnO process is that you end up with a mess from that whose separation involves filtration, crystallization, followed by vacuum distillation (BP Propylene Carbonate 242C @ ATM).

Non-aqueous routes are exciting, plus they can be tested quickly and easily with a power supply so long as you have your solvent and your salt. But selecting the proper counter ion and solvent... that's the crux of the issue. I would love to see some of your attempts however. I myself had a great many flings electrolyzing lithium chloride in DMSO before after quite a bit of searching I discovered I was making methyl lithium. And what beautiful methyl lithium it was ;)




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[*] posted on 5-3-2014 at 05:59


Quote: Originally posted by elementcollector1  
Adding a catalyst of ZnO is supposed to give 98% yield...


The 9% yield I got was with the ZnO.




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[*] posted on 5-3-2014 at 06:13


Unfortunately, the old reference I had died for whatever reason. However, I did find this: http://www.doiserbia.nb.rs/img/doi/1451-9372/2011/1451-93721...
It uses metal carbonates instead of metal oxides.
How did you prepare your ZnO? Was it calcined?




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[*] posted on 5-3-2014 at 07:10


Has anybody tried just electrolyzing in a hydrocarbon such as pentane, hexane, or heptane?



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[*] posted on 5-3-2014 at 07:42


I've tried two cations that I can remember off the top of my head; lithium, and calcium.

My experience with lithium was somewhat disappointing. Don't underestimate how dry the acetone (and lithium chloride) must
be. I was never able to get more than just a thin film of lithium at one time, just enough that it would "fizz" when I
dunked the electrode into water. Never enough to actually collect.

I tried electrolyzing calcium chloride in ethanol. That didn't work too well either, but again, I got enough to react with water
when the electrode was submerged in it. One thing I found was that the process did not work too well if the alcohol was
absolutely dry. I had to add a drop or two of water to it to get things going. The process was a clever balance between water
content, current density, and salt concentration.
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[*] posted on 5-3-2014 at 07:47


TheChemiKid, there are many criteria for it to work as a suitable solvent (e.g. it can't react, must allow salt to ionize ect.)
blogfast25, excellent link, very informative thank you.

I will buy my Propylene carbonate, I've got some $50.00 designated for this project.

Quote:

At a minimum, try and dig up the references of that section of the paper, before trying anything...

I read all the references that he listed pertaining to the subject.

Quote:

My experience with lithium was somewhat disappointing. Don't underestimate how dry the acetone (and lithium chloride) must be.I was never able to get more than just a thin film of lithium at one time, just enough that it would "fizz" when I
dunked the electrode into water. Never enough to actually collect.


Hmmm, well that's about what I would expect. I will keep the container completely sealed off, (to keep it from absorbing water.) How much current did you use? Voltage?
At least it worked, that's incourageing.
Since I already have lithium, I may try to get sodium from NaClO3, as shown in blogfast25's link. (The reason that I changed the subject of this discussion.) Potassium is another goal....




[Edited on 5-3-2014 by Zyklonb]




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[*] posted on 5-3-2014 at 08:11


Quote: Originally posted by elementcollector1  

How did you prepare your ZnO? Was it calcined?

I prepared it by heating zinc hydroxide (from the reaction of zinc chloride and sodium hydroxide). I did not calcine it.

A full report of my synthesis is in this thread.




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[*] posted on 5-3-2014 at 16:05


Ok, I'm about to purchase this propylene carbonate. Does it look like it will be a good choice?



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[*] posted on 5-3-2014 at 16:18


Quote: Originally posted by Zyklonb  
Ok, I'm about to purchase this propylene carbonate. Does it look like it will be a good choice?

I dont see why not. Don't be surprised though if the electrolysis does not work at first, since there will no doubt be water and other contaminants that react with the propylene glycol.




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[*] posted on 5-3-2014 at 18:49


No doubt, I will have to dehydrate my propylene carbonate and whatever salt that will be electrolyzed (probably not the right term.) All experiments will be controlled in a dedicator, and will be handled only occasionally, and briefly.
I couldn't find any information on dehydrating propylene carbonate.:( .




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[*] posted on 6-3-2014 at 00:02


I imagine that if it only contains a small amount of water you could start electrolysing it, and LiOH would form until the propylene glycol was fully dehydrated, then Li woul be produced. Its quite possible that I am wrong, but its worth a shot I think. As for how to dry it, distill over sulfuric acid? H2SO4 at 180 degrees will dehydrate just about anything.



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[*] posted on 6-3-2014 at 05:37


That's what I would do, but I don't have a distillation setup....
It's quite close to anhydride, so I might be able to use it as is.




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[*] posted on 6-3-2014 at 06:17


Quote: Originally posted by Oscilllator  
I imagine that if it only contains a small amount of water you could start electrolysing it, and LiOH would form until the propylene glycol was fully dehydrated, then Li woul be produced.


Actually, if there is water it will be electrolysed first because H<sub>3</sub>O<sup>+</sup> is much, much easier to reduce than Li<sup>+</sup>.

So start running a low voltage that gives you some current, thus eliminating the water, then increase potential to start reducing Li.

[Edited on 6-3-2014 by blogfast25]




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[*] posted on 6-3-2014 at 06:32


That's a good idea. Thanks.



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[*] posted on 6-3-2014 at 06:39


Quote: Originally posted by Zyklonb  
That's a good idea. Thanks.


And DO report back: I think we're all dying to know how this pans out! :cool:

It would probably help to dry the solvent overnight over anh. MgSO4 and oven dry the LiCl at 120 C for a couple of hours, just prior to use. Oven dry your cell too...

[Edited on 6-3-2014 by blogfast25]




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[*] posted on 6-3-2014 at 07:10


Definitely, I'll report my progress here, and in the Successful experiments topic, if it works:). If not, You'll likely find it here.
MgSO4 will be used to dry the propylene carbonate. I plan on first using NaClO3 to make sodium, to avoid have to buy another chemical. (I don't have any LiCl.) NaClO3 may prove to be hard to dry.... A day in the oven should do it.
[EDIT] Damn, I just ruined my 500th post.... International Hazard! :D



[Edited on 6-3-2014 by Zyklonb]




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