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Author: Subject: Make Potassium (from versuchschemie.de)
mr.crow
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[*] posted on 1-12-2010 at 18:44
Make Potassium (from versuchschemie.de)


Here is something cool I found, not mine of course

http://www.versuchschemie.de/topic,14677,-Synthese+von+Kaliu...

Translation




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Jor
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[*] posted on 1-12-2010 at 19:38


Funny thing. The minute you posted it I also found out and was reading it :P
I immediately wanted to do this as well. However, I will make slight modifications, I will use i-PrOH instead of t-BuOH.
Also I don't know where to buy Shell D70 solvent, so i will use some high boiling hydrocarbon such as mineral turpetine.
I will still have to order some magnesium. I have some ribbon, I think i will use that to try it this weekend, but it's not enough to prepare more than a gram or two (I don't want to waste all the ribbon).
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UnintentionalChaos
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[*] posted on 1-12-2010 at 20:00


I think I'll be trying this with sodium, asap. I lack solid KOH presently...



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[*] posted on 1-12-2010 at 20:16


Very nice thread there! and patent.

What is the purpose of the alcohol in this reaction? Does it react with the KOH to make a more soluble K alcoholate in the shellsol solvent, thus increasing the reaction rate?

I also wonder if solid paraffin from candles could be used instead of shellsol d70.
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BromicAcid
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[*] posted on 1-12-2010 at 20:20


The thread for this is laying around here somewhere. I tried this back in 2005 using KOH and isopropanol in kerosene with promising results but never revisited it.

http://www.bromicacid.com/experiments/october2005.php#a

In the thread on this site however someone had tried to repeat the experiment and failed to have any positive results. I think this dissuaded others from attempting the experiment. It's amazing how similar some of the pictures look on that site, I could have recognized the reaction by sight :)

Edit: It was Len1 that tried the experiment on this site, most of the discussion is here (although it starts on previous pages):

http://www.sciencemadness.org/talk/viewthread.php?tid=2105&p...

Edit: Condennnsa, I do believe as you indicated that the alcohol acts as a phase transfer catalyst of sorts to help bring the KOH into solution so it can react with the magnesium surface. Isopropanol seemed to work but I think that a more non-polar alcohol such as t-butanol would give superior results as in the patent. Part of my lack of success may have also been due to adding all reagents together then heating rather than a feed of alcohol.

[Edited on 12/2/2010 by BromicAcid]




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[*] posted on 1-12-2010 at 20:23


Fascinating, and elegant! Wouldn't have thought it possible (elemental K by chemical means under such mild conditions). I will be interested to see whether isopropanol actually works as well as the tert-butanol...
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[*] posted on 1-12-2010 at 21:01


A fascinating thread indeed but if you read the comments, attempts to reproduce the results with gear oil, kerosene and paraffin oil in place of Shellsol D70 were all failures.



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MagicJigPipe
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[*] posted on 1-12-2010 at 21:19


This is absolutely amazing. And I was still pondering over electrolysis to obtain alkali metals in propylene carbonate (with AlCl3 catalyst). Will isopropanol work for this? I don't see why not. Potassium isopropoxide should form with just a little bit more difficulty, right?



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condennnsa
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[*] posted on 2-12-2010 at 05:19


Well I'm completely confused. Like BromicAcid said, Len1 tried the exact same procedure in the unconventional sodium thread , following the patent precisely. And had zero success. No reaction.
He said that he thought the patent is bogus.

Yet on the Versuchschemie.de forum we see those beautiful blobs of potassium. Why would the guy on the german forum lie!? i don't get it

[Edited on 2-12-2010 by condennnsa]
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mr.crow
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[*] posted on 2-12-2010 at 07:26


It seems people here are too happy to substitute different reagents. Maybe you really need tBuOH and everything has to be anhydrous and at the right temperature. Sort of like how Mg can form grignards or remove the last bit of water from anhydrous alcohol.

I don't know why he would lie, it would have to be the nerdiest troll in history. Why would the patent lie? Those are expensive to get.

I didn't know its already been tried here, but now that we have a new thread everyones seen it :)




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[*] posted on 2-12-2010 at 07:34


Quote: Originally posted by mr.crow  
It seems people here are too happy to substitute different reagents. Maybe you really need tBuOH and everything has to be anhydrous and at the right temperature.


Well Len1 said that he did use t-BuOH as well as shellsol d70. Check the link provided by bromicacid, on page 9

This got me really excited, now I'm boiling some mg chips with NaOH in paint thinner, refluxing it. It doesn't have nearly the boiling point required, it boils at about 80C, I just want to see if anything happens. I also added a few drops of isopropanol. So far, nothing happened. There seem to be no gas bubbles on the surface of the Mg chips.
The liquid did get slightly darker, which i can't explain...
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[*] posted on 2-12-2010 at 07:48


Wow!

As the first commeter over there wrote: 'Geil, mir fehlen die Worte !' ('Blimey, words fail me!').

I remember the len1 thread and what dissapointment it caused. So does this really work? A heterogenous reduction of KOH with Mg? You'd expect a fair amount of heat to be developed...
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[*] posted on 2-12-2010 at 07:51


Quote: Originally posted by mr.crow  
I don't know why he would lie, it would have to be the nerdiest troll in history. Why would the patent lie? Those are expensive to get.

I didn't know its already been tried here, but now that we have a new thread everyones seen it :)


There are shedloads of non-functioning patents out there: often companies patent something on an educated hunch, prior to actual testing, just to beat potentila competitors to it.

I'd advise anyone trying this to stick rigorously to the recipe, at least at first...
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UnintentionalChaos
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[*] posted on 2-12-2010 at 07:53


Quote: Originally posted by condennnsa  
Quote: Originally posted by mr.crow  
It seems people here are too happy to substitute different reagents. Maybe you really need tBuOH and everything has to be anhydrous and at the right temperature.


Well Len1 said that he did use t-BuOH as well as shellsol d70. Check the link provided by bromicacid, on page 9

This got me really excited, now I'm boiling some mg chips with NaOH in paint thinner, refluxing it. It doesn't have nearly the boiling point required, it boils at about 80C, I just want to see if anything happens. I also added a few drops of isopropanol. So far, nothing happened. There seem to be no gas bubbles on the surface of the Mg chips.
The liquid did get slightly darker, which i can't explain...


The temperature is quite important. If potassium (or sodium in your case) is indeed formed, the mix would need to be above the melting point to allow it to ball up.




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[*] posted on 2-12-2010 at 08:13


Interesting experiment. What would be the simplest apparatus/setup to "reflux" the process?

The idea of boiling kerosene is a bit scary, but the result would definitely be total awesomeness!

Robert
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[*] posted on 2-12-2010 at 08:24


Quote: Originally posted by Arthur Dent  
Interesting experiment. What would be the simplest apparatus/setup to "reflux" the process?

The idea of boiling kerosene is a bit scary, but the result would definitely be total awesomeness!

Robert


A long vertical tube... Inert material and aircooled if possible...
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[*] posted on 2-12-2010 at 08:28


It gets crazier: the patent he quoted claims production of cesium from CsOH!
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[*] posted on 2-12-2010 at 08:36


The post on versuchschemie describes heating the shellsol d70 to reflux (that's 200C), with hydrogen evolved mostly in the temperature range of 100-130C. Also the tert-butanol / solvent mix gets added while the solution is still at 200C. I don't think low-boiling solvents are going to cut it.

Quote:
There are shedloads of non-functioning patents out there


No doubt! And if it were just a patent, I'd consider Bromic and len1's experiments a fairly decisive refutation of the claims. But now we have a new claim of reproduction, complete with pretty pictures. It's either a very elaborate troll, or else there is some detail that we're missing; take your pick. Who knows, maybe some naphthene compound that is intermittently present in the shellsol in small quantities (depending on batch :-) ) acts as a catalyst ...
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[*] posted on 2-12-2010 at 08:58


From what I undertand it's realy more a reduction of potassium alcoholate; that makes it a lot more plausible, assuming the alcoholate is soluble in the main solvent...

Low boiling solvents won't do it, I'm pretty sure of it...



[Edited on 2-12-2010 by blogfast25]
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[*] posted on 2-12-2010 at 09:03


Now is the time to buy a tonne of Shellsol! :D
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Arthur Dent
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[*] posted on 2-12-2010 at 09:17


Shellsol D70 has a composition of 60% parrafins and 40% Naphtenes, according to Shell's data sheet. I checked for availability and it's available in canada, I'll have to enquire if it's available in small quantities.

- Robert


[Edited on 2-12-2010 by Arthur Dent]
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[*] posted on 2-12-2010 at 10:04


Here a recent datasheet for Shellsol D70. Link is in PDF form.
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[*] posted on 2-12-2010 at 10:29


I really do not know what to think about this. His procedure is significantly different to the patent and I know that some patents are quite frankly fiction.
My gut feeling is that the reaction just would not occur.
Potassium reduces magnesium chloride to form Rieke magnesium, see below;
http://en.wikipedia.org/wiki/Rieke_metals
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[*] posted on 2-12-2010 at 10:53


Thermodynamically it makes sense though: NaOH HoF 298 K = - 426 kJ/mol, KOH HoF 298 K = - 425 kJ/mol, MgO HoF 298 K = - 606 kJ/mol:

NaOH (KOH) + Mg - Na (K) + MgO + ½ H2 HoR 298 = -602 + 426 = -176 kJ/mol. Quite a bit of heat... This would be typical of quite a slow reaction which is what we're seeing...

It can be shown that the Rielke reactions take place too with the same logic.

Other example: reduction of AlCl3 with K (or Na) but also reduction of NaOH with Al powder or Mg...

If the t-butyl alcohol somehow solubilises the KOH then that's half the work done...


[Edited on 2-12-2010 by blogfast25]
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[*] posted on 2-12-2010 at 11:10


Possible mechanism:

KOH + t-butanol -> K t-butanolate + H2O

Equilibrium driven to the right by evaporating H2O and by

2 K t-butanolate + Mg - 2 K + Mg t-butanolate

Mg t-butanolate + H2O - MgO + t-butanol
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