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Author: Subject: Make Potassium (from versuchschemie.de)
len1
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[*] posted on 21-12-2010 at 14:52


Yes, thats what I was saying up the thread, that you can coalesce potassium a few degrees within its mp, above that it is just too fluid. But I dont need isopropanol for that, it just happens with straight potassium in D70.

Wilco, Ive also tried your method with no stirring except when adding the butanol, but this time I got a load of potassium shot, much like blogfast was getting (a very dangerous mix). Maybe coalescence in this case is a random event, or perhaps its a function of the particle size of magnesium.

[Edited on 21-12-2010 by len1]
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[*] posted on 21-12-2010 at 15:33


Holy Cow blogfast25, you're lucky your "pyrex" measuring cup didn't explode.

regarding teflon, K metal seems like one of the only things that can pry Fluorine away from its carbonaceous slumber




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[*] posted on 22-12-2010 at 00:00


Quote: Originally posted by NurdRage  
Quote: Originally posted by Nicodem  
Higher t-alkoxides (t-amyl alcohol and above) might speed up the reaction if the limited solubility of t-butoxides is found to be an issue.


On this point i'd like to add my purely qualitative observation that t-amyl alcohol did seem to give me greater rate. the hydrogen bubbles seem to go twice as fast than my trials with t-butanol.

I only tried t-amyl alcohol once though and thus i can't say definitively that it's better. But from what i did see, i think it's worth exploring longer chain alcohols.


Nurdrage this is awesome news as t-amyl alcohol is definately easier to get than t-butyl alcohol for me. It can easily be made using ethyl bromide and acetone as reagents in a grignard reaction.
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[*] posted on 22-12-2010 at 00:14


According to the theory above, my experiments with magnesium turnings 3 years ago failed because they lacked sufficient fresh surface after the reaction with water to initiate the main reaction.

I hence repeated the experiment using 1.6gm Mg powder as before, and 5gm Mg turning produced by 12mm drilling into an Mg block. The latter are much cheaper, economizing on the more expensive powder normally reserved for Grignards.

An initial load of 1.0gm Mg powder was added to the mixture and heated to 150C to dehydrate the KOH. The theoretical amount further up the thread is 0.84gm so a slight excess was used. The dehydration reaction does not occur in the D70 bulk, but in the bottom layer where the Mg contacts the molten KOH, hence the use of the powder for this reaction.

After H2 evolution slowed, the remaining 0.6gm Mg powder and 5gm Mg turnings were added to the flask, so the reagents now looked exactly like in the photo 3 years ago, with the turning protruding slightly above the D70 surface. t-BuOH was added, and initiated the reaction, so potassium globules soon appeared on the surface.

The H2 evolution now and the magnesium turning started to slowly disappear. After 5hrs they were completely absent, and this time the reaction produced little sand. The yield appears to be as before (will know exactly tomorrow).

The formation of MgO crust or sand seems to be a function of the reaction rate, wth slow reactions favouring crust. This in turn is governed by Mg particle size.

[Edited on 22-12-2010 by len1]
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[*] posted on 22-12-2010 at 01:44
Deactivated magnesium test


I know it might seem obvious that "deactivated" magnesium shouldn't work, but i thought i'd try it anyway to make certain we're not missing anything.

Abstract: Deactivated magnesium doesn't work to make potassium


So i ran another run using all the same reagents i used in my original paraffin run (25mL paraffin oil, 5g KOH, 2g Mg, 1mL t-amyl alcohol).

But this time I "deactivated" the grignard-quality magnesium turnings by first soaking them in tap water for two days, allowing to dry, then soaking in water for one more day, and then drying in an oven at 130celsius. The magnesium came out very dull brownish with visible powdery appearance.

I ran the reaction using the same conditions and while the first dehydration/hydrogen evolution step worked fine, after adding the alcohol the hydrogen evolution was extremely slow, despite using the more active t-amyl alcohol.

after 2 hours of heating no potassium formation was observed. The reaction was allowed to cool and i did a hard-test by pouring water directly into the mixture. A bit of bubbling accord due to the exothermic solvation of KOH. But no flaming characteristic of potassium metal. Magnesium turnings were still present and by eye it appeared mostly unchanged.



-----> Bottom line the quality of magnesium does play a role. While we've all proven with our different sources that it's not critical, I've shown here that it can be sole cause of a bad run. So when troubleshooting a particular run, care must be taken to use reasonable quality magnesium.

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[*] posted on 22-12-2010 at 06:42


Quote: Originally posted by len1  
Wilco, Ive also tried your method with no stirring except when adding the butanol, but this time I got a load of potassium shot, much like blogfast was getting (a very dangerous mix). Maybe coalescence in this case is a random event, or perhaps its a function of the particle size of magnesium.

[Edited on 21-12-2010 by len1]


len1:

How long did you cook for this time? My experiments were resp. cookimg times of 2 h and 1 1/2 h, so much shorter than your initial ones... and wilco's (and pok's).

And why do you refer to the smaller globules as 'a dangerous mix'?



[Edited on 22-12-2010 by blogfast25]
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[*] posted on 22-12-2010 at 06:43


Quote: Originally posted by mr.crow  
Holy Cow blogfast25, you're lucky your "pyrex" measuring cup didn't explode.


Calm down, I've used some of my pyrex jugs for years on end: yes, with direct flame...
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[*] posted on 22-12-2010 at 06:51


Quote: Originally posted by NurdRage  


I ran the reaction using the same conditions and while the first dehydration/hydrogen evolution step worked fine, after adding the alcohol the hydrogen evolution was extremely slow, despite using the more active t-amyl alcohol.



Nurd: you now seem very sure of your case for the 'more active t-amyl alcohol', do you have more data? And are we definitely talking about 2-methyl-2-butanol as 't-amyl alcohol'?
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[*] posted on 22-12-2010 at 06:57


Quote: Originally posted by blogfast25  
Quote: Originally posted by mr.crow  
Holy Cow blogfast25, you're lucky your "pyrex" measuring cup didn't explode.


Calm down, I've used some of my pyrex jugs for years on end: yes, with direct flame...
In the US, the brand name "Pyrex" is no longer made from borosilicate glass. In Europe (including the UK), it still is. For as many times as this has come up, it's apparently not yet common knowledge.
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[*] posted on 22-12-2010 at 06:58


Quote: Originally posted by len1  
According to the theory above, my experiments with magnesium turnings 3 years ago failed because they lacked sufficient fresh surface after the reaction with water to initiate the main reaction.

I hence repeated the experiment [...]
What was the stirring regime you used here? I infer from the description that you weren't stirring in the dehydration phase. You've reported up-thread that stirring seems to inhibit the initiation phase. What did you do here?
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[*] posted on 22-12-2010 at 07:01


Quote: Originally posted by watson.fawkes  
Quote: Originally posted by blogfast25  
Quote: Originally posted by mr.crow  
Holy Cow blogfast25, you're lucky your "pyrex" measuring cup didn't explode.


Calm down, I've used some of my pyrex jugs for years on end: yes, with direct flame...
In the US, the brand name "Pyrex" is no longer made from borosilicate glass. In Europe (including the UK), it still is. For as many times as this has come up, it's apparently not yet common knowledge.


I have confidence when the label of 'kitchenware pyrex' states that it can be used directly for cooking that that is the case. I have had one or two of these babies crash when I cooled them down too quickly, mainly due to the thickness of the glass which causes big temp. differentials and hence large stresses. Other than that they're very sturdy and much cheaper than lab beakers. But they don't do then in 'conical' or 'round'...;)

[Edited on 22-12-2010 by blogfast25]
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[*] posted on 22-12-2010 at 07:06
More Experimenting


Hello all,

Well this is probably one of the best experiments ever posted on “Science Madness”. Just wish I had some tertiary alcohol, and Shellsol D 70. I could use Paraffin oil, but with the holidays, and etc. I have no funds to buy more chemicals for awhile and still no tert’s.
So hoping someone else will carry out more experiments, the patent says, preferred reaction accelerators are alcohols having 3 to 8 carbon atoms, such as propanol, butanol, pentanol, particularly tertiary butanol or tertiary pentanol. It does NOT say that we have to use Tert’s, but only that they are better. Experiment with some other 3 to 8 carbon atom alcohols. Maybe n-butanol or sec-butanol, and etc.. Maybe with longer heating times or more alcohol?
Also even though the patent does not state the use of Aluminum, why not try it and also Al/Mg or Al/Hg. Maybe longer times would be better here also?
Hope my funds are better in the new year. I could really use some Potassium.
Keep up the great work everyone and have a great New Year, the Alchemist…..


[Edited on 22-12-2010 by Alchemist]
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[*] posted on 22-12-2010 at 07:30


Quote:
I know it might seem obvious that "deactivated" magnesium shouldn't work, but i thought i'd try it anyway to make certain we're not missing anything.


Doing trials to verify negative results? That's hard core... It's almost like you're a scientist or something :cool:
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[*] posted on 22-12-2010 at 07:53


So NurdRage, are you making a video for your channel about making the K? :P

I would be quite interested !
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[*] posted on 22-12-2010 at 10:21


Some K globules made with pok’s reaction, coalesced from very small ones in kerosene at temperatures close to the MP of K (63.6C). The largest one is about 1 cm diameter. they're in Shellsol D70:



More globules and more commentary to follow...

[Edited on 22-12-2010 by blogfast25]
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[*] posted on 22-12-2010 at 11:20


I still think the commonly available glycol ethers may work. (Brake Fluid)
Has anyone tried Barbier reaction of acetone, MEK, or cyclohexanone with zinc and alkyl bromides using the ketone itself as solvent to make tert alcohols?

[Edited on 12-22-2010 by Eclectic]
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[*] posted on 22-12-2010 at 13:52


Well, well. I tried to coalesce the rest of my fines, this time using Shellsol D70 but it seems to be slower than in kerosene (subjective).

Soon I’ll try with a very low viscosity solvent like heptane or octane: lower viscosity means all other things being equal that the layer of solvent between two adjacent globules is thinner and that must be beneficial for coalescence…
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[*] posted on 22-12-2010 at 15:47


In response to nurdrages post about deactivated Mg, I took a chunk of Mg that was sitting in water for a couple days and for the most part has stopped producing hydrogen so I decided to run a quick and simple test.

I took that large piece of Mg and dipped it into HCl holding it there for just a little while as it cleaned and pitted itself. I then washed it under a steady stream of water and then dried it, I once again washed it to ensure all acid was removed.

I compaired this side by side in plain old water with a fresh turning which came from a block of Mg.

The activity of the HCl washed Magnesium was roughtly 2x that of the fresh turning judging from the hydrogen production.

=================================================================================


Is there anything I can add to molten Mg to increase surface area such as sand or possibly carbon? I ask because the slag that formed while I was cleaning the dirty Mg was in the order of 5-10x more active then the pure Mg itself.

If some sort of inert filler could be added then it may very well step this reaction up a notch and make the entire process faster and simpler.



PS: Anyone here have the balls to Ballmill Mg/KOH and an inert solvent to see if any Potassium is produced? I think it may work at a very low temperature but I don't have the time to baby sit it and its not something I wish to leave unattended for even a few seconds.:o ..... Im also sensing a low temperature Phosphorus production variant stemming from this reaction something in the future.





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[*] posted on 22-12-2010 at 16:05


Very cool stuff! I've been thinking about trying out the experiment soon, and have gathered many components.

Since it seems that even dry KOH still contains enough water to affect the reaction, would boiling the straight potassium hydroxide in the solvent for a little while before adding the other reagents permit to "drive off" the remaining water and permiting a relatively anhydrous mix of solvent and KOH?

For the reaction apparatus, would a small graham condenser topped-off with a bubbler be a good method of preventing air from entering the vessel? Or would this be overkill?

Given the relative rarity of the "magic ingredient", namely the Shellsol solvent, would it be possible to make our own by mixing 60% kerosene with 40% cyclohexane? According to the Shell MSDS, it might be a relatively similar "formula" ...

See the quickly-drawn (sorry) sketch below:



in this setup, the condenser would be hooked-up to a cool water source, secured with a neoprene stopper to a 3-neck boiling flask, on top would be a small plastic bubbler filled with solvent, secured with a stopper, and the two remaining neck of the flask would be for temperature monitoring and t-bu addition.

My next task will be to find a proper source of KOH, because the reagent-grade stuff is too expensive.

Thanks for any suggestions and recommendations.

Robert
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[*] posted on 22-12-2010 at 17:54


Quote: Originally posted by Arthur Dent  

Since it seems that even dry KOH still contains enough water to affect the reaction, would boiling the straight potassium hydroxide in the solvent for a little while before adding the other reagents permit to "drive off" the remaining water and permiting a relatively anhydrous mix of solvent and KOH?
I don't think so. If this would be possible, the patent would probably recommend this because this would decrease Mg consumption. I could imagine that the water can't evolve out of the hydrophobic solvent and would rather stay at the KOH even at high temperatures. But I don't know exactly.
Quote: Originally posted by Arthur Dent  
For the reaction apparatus, would a small graham condenser topped-off with a bubbler be a good method of preventing air from entering the vessel? Or would this be overkill?

I think this would be a good idea. condenser = reflux, bubbler = air exclusion. If you carefully control the temperature you can use a simple (but sufficiently long) glas pipe as a reflux condenser. But if you have a graham condenser why not using it? And the idea with a bubbler is a great idea, I think. I will use it :D the next time instead of a stupid balloon. Of course, this will only work as long as you don't change the temperature of your mix up and down very often. If you do so: air would bubble from the outside despite (or because of) using such a bubbler because of increasing and decreasing pressure in your reactor. The same effect may occure at occasionally swirling the reactor (cooling down while taking and swirling it -> decrease of pressure -> influx of air through the bubbler) Hydrogen evolution within the 4 hours of reaction can be very slow and will not guarantee a constant efflux! But if you keep the temperature quite constant it will work very well, I think.
Quote: Originally posted by Arthur Dent  
Given the relative rarity of the "magic ingredient", namely the Shellsol solvent, would it be possible to make our own by mixing 60% kerosene with 40% cyclohexane? According to the Shell MSDS, it might be a relatively similar "formula" ...
I think this wouldn't make sense. The cyclohexane would vaporize at 81°C and would be lost (or only present in the vapour above your reaction mix)!! If you can find a 200-250°C boiling kerosene free from aromatics (like shellsol D70) and mainly C11-C14 paraffines (like shellsol D70) it should work.
Quote: Originally posted by Arthur Dent  
See the quickly-drawn (sorry) sketch below:
The sketch looks fine;)
Quote: Originally posted by Arthur Dent  
My next task will be to find a proper source of KOH, because the reagent-grade stuff is too expensive.
Ebay KOH should be good enough. Maybe you can find a store which sells raw materials for home-made soap production (internet or elsewhere). They sell NaOH, KOH and other stuff in sufficient quality (I got some of my KOH from such a store and used it successfully).

[Edited on 23-12-2010 by Pok]
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[*] posted on 22-12-2010 at 18:01


Does anyone have any idea as to the purity of Mg in Coleman firestarters from Wal-Mart? I suppose regardless of the purity, if it works this will be a great source of Mg/K for those that, for some reason, cannot obtain it over the internet or do not wish to.

That's all I have at the moment. My attempt will be done with OTC Mg and inert reaction medium.

Crossing my fingers...

EDIT:

I almost feel bad about posting a source on here because things like that seem to disappear from shelves. Should I take it off?

Also, Pok, I don't think the boiling point of the solvent is extremely critical as long as it is higher than ~200*C or so, right? If it is critical, why? The only thing I can think of is agitation of the reaction mixture.

And are we absolutely certain that low aromatics is a necessity? I see we have some evidence that supports that hypothesis but we can't be quite certain yet. I suppose alkali metals are more likely to react with aromatics... That makes sense then... Could it just reduce yield instead of somehow poisoning the reaction?

[Edited on 12-23-2010 by MagicJigPipe]




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[*] posted on 22-12-2010 at 23:15
Possibly a Substitute for Shellsol


http://www.homedepot.com/catalog/pdfImages/ab/ab478e2b-db4c-...

Looks like an OTC substitute for shellsol. Its a high boiling point aliphatic petroleum distillate according to the MSDS.
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[*] posted on 22-12-2010 at 23:42


But it's boiling point is "greater than" 316*F which is only 158*C. It would have to be MUCH greater to be on par with Shellsol.

I suggested using Naptha earlier. Then I realized that the boiling points I was seeing were in fahrenheit rather than celsius (I have become so accustomed to reading temperatures in C). So, when I saw a boiling points of 200-300 degrees, I thought, "Hey, this should work!". Wrong...




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[*] posted on 23-12-2010 at 00:16


Blogfast - I always let the reaction go 4-5hrs. In this case I used woelens's sand bath on a hot plate with sand temperature controlled. It did not work under my conditions, although we can clearly see it worked for Wilco. I had to drain the entire solid mass from D70, the added the dioxan. Its slighlty wet so the potassium fizzed. The on heating to 80C on an oil bath it rose to the top and coalesced with slight shaking into a blob about 4cm diameter. This is quite a good method, because the slight amount of moisture in the dioxan generates a protective atmosphere inside the reagent bottle. I used schott plastic capped bottles, tightly shut after initial hydrogen release, immersed in an oil bath at 80C. The K rises to the top and you can leave even small shot there to coalesce over 1-2hrs. The final aggregation can be done by gentle rocking for the last few inutes. It seems theres some force attracting potassium balls to each other - because they seem to 'know' where each other is.

The dioxan is obv mixing with a bit of D70 - no problem, I can distill it off and use again.

The potassium shot is dangerous outside D70, where it can spontaneously burst into flame, especially in solvent such as xylene and toluene.

I cant unfortunately change - I have no edit privelages on what I posted ages ago. I would however like to apologize to Pok (but he should learn how liquid density changes with T in almost all cases, esp far from melting point)


[Edited on 23-12-2010 by len2]

[Edited on 23-12-2010 by len2]
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[*] posted on 23-12-2010 at 00:23


len, I'd like to suggest that you change what you said about this patent in the Sodium metal - illustrated practical guide , now we know the patent is genuine, and the procedure works, just so we keep the sciencemadness prepublication section accurate.
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