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Author: Subject: Make Potassium (from versuchschemie.de)
blogfast25
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[*] posted on 10-12-2010 at 10:11


@plastics:

You seem to be injecting the t-butanol straight into the solvent, that’s what I’m planning to do too…

Try if you can to take stock of temperature in the reactor. A household digital thermometer up to 200 C with needle like probe (straight through the bung!) will set you back about 10 quid, Was the solvent at least boiling?

What's the internal diameter of your 'refluxer'?
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[*] posted on 10-12-2010 at 12:45


Quote: Originally posted by plastics  
There is certainly initial generation of gas after gentle warning and I am able to get the tert butanol to reflux successfully (see pictures). After a couple of hours I just end up with a sludge of magnesium turnings and white powder (? MgO ? Mg(OH)2 this is definitely not the KOH flakes I started with)
Could be potassium tert-butoxide. As Nicodem mentioned, its solubility goes up with temperature. I'll second the blogfast25's call to measure the temperature.

When you're done, it would be useful to know how much of the tert-butanol remains free and how much has reacted. A very simple distillation would be adequate, given the large difference in boiling points.
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[*] posted on 11-12-2010 at 00:33


@plastics , it is really disappointing to me to see you failed... considering you used the right alcohol, i think you should've gotten something.

Did the remains of the reaction at least bubble in water when you washed it down?

Let's just see how woelen's setup turns out , but i have a feeling he won't succeed.

would've been awesome to see this work..
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[*] posted on 11-12-2010 at 10:39


I also tried the experiment twice. Both experiments failed.

One time I tried the safe way in a sand bath with temperature monitoring. The temperature remained between 200 C and 250 C during the entire experiment. I used a 10 times as small a scale as Pok did.
Below follow pictures of the setup I used. The third picture shows that the test tube is filled with white fumes and the glass is wetted. There is some refluxing of t-butanol. The fourth picture shows a typical temperature readout during the experiment and the final picture shows the result.

Unfortunately the result is no potassium at all. Definitely there is some reaction (evolution of gas and formation of a white solid, other than KOH), but no potassium metal is formed.



setup.jpg - 50kB setup2.jpg - 47kB

reflux.jpg - 36kB temperature.jpg - 26kB

result.jpg - 38kB



[Edited on 11-12-10 by woelen]




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[*] posted on 11-12-2010 at 10:51


So, in the first experiment I had no results. I added the t-butanol, dissolved in some paraffin oil in two steps with 20 minutes in between by letting it run through the thin glass tube (I did not want the air to be replaced inside the test tube). Initially, before heating, I flushed the air in the test tube with butane gas to be sure that no oxygen remained. I capped the glass tube with a thick dash of paper tissue which was wetted. At the start of the experiment a small amount of gas was released through this outlet, lateron, I pushed it firmly on the tube and no exchange of gas seemed to happen anymore.
I have kept the test tube in the hot sand bath for around 1 hour and then I allowed it to cool down slowly (which took another hour). Not the faintest sign of formation of potassium. No shiny globules. Pok states that in 20 minutes, but certainly in 30 minutes after adding the tert-butanol one should clearly see shiny globules of potassium. Nothing at all!


In the second experiment I did something unwise ;)

I went outside, took a test tube and put in fresh reagents and with a clamp, I kept the test tube above (not in!) the flame of a propane torch. I did this outside just in case the test tube would crack and the very hot mineral oil would catch fire. With this setup much higher temperartures are possible. I had a very vigorous reaction in this experiment. A thick white cake formed, sticking at the glass and excess Mg-powder was floating around in the mineral oil. I allowed this situation to last for around 30 minutes after adding the tert-butanol, but again no potassium is formed. Part of the Mg reacts, a lot of gas and white smoke is produced, but no K-metal. The vigorous reaction only lasts for a few tens of seconds, after that I had a clearly visible formation of gas, but it was not violent at all.

The KOH, used in my experiments is in the form of half-spheres, diameter around 4 mm and thickness at most 2 mm. The Mg is in the form of moderately fine powder (according to label it is 65 um to 100 um particle size).


Tomorrow I hope to find the time to try the reaction with Mg/Al instead of Mg. My Mg/Al is a fine powder, sold to me as magnalium for pyro purposes. It, however, also is a fine reductor and that is what I am using it for.


[Edited on 11-12-10 by woelen]




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[*] posted on 11-12-2010 at 10:56


@ woelen:

Can you describe your experiments in a little more detail? Duration? Introduction of t-butanol, how and when? Was the solvent effectively boiling?

ooops, you beat me to it!

[Edited on 11-12-2010 by blogfast25]
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[*] posted on 11-12-2010 at 11:07


Actually, I am somewhat disappointed with this result. I really tried to assure that the conditions are like what Pok had. I used temperature monitoring (I was babysitting the whole thing and when temperature went below 220 C I switched on the hot plate and when it went above 240 C I switched it off again, and I'm sure that the temperature never went below 200 C and never went above 250 C). I have used the ratios of Pok and I swirled the test tube just a few times, just as Pok did with his erlenmeyer. I took away the initial oxygen to be sure that no excess magnesium is oxidized in the process and I have used a thin glass tube of approximately the same length as Pok did for the 'refluxing'.

There must be some 'magical' thing with the ShellSol D70, or the piece of magnesium, used by Pok was special. It was some piece of scrap, which most likely is not pure but contains other allied metals.




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[*] posted on 11-12-2010 at 11:28


@woelen:

I bet you are, so are we all (disappointed).

You’re starting from the assumption that pok’s results are genuine (and not a hoax) and that they are dependent on some ‘hidden parameter’, right? It’s possible. It just doesn’t really ring true with me.

Most likely (again assuming his experiment is genuine) it would be some overlooked form of catalysis.

Next we’ll be holding a collection for a representative of SM to fly to Germany and go watch <i>jackpok’s</i> ‘magic’ in the flesh (I just hope he’s not an illusionist as well as a hoaxer! ;)
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[*] posted on 11-12-2010 at 11:45


Yes, up to now I assume that Pok is honest. It might be that he won the 'jackpok' but if that is the case then it is a job for us (and him) to find out what is the 'hidden luck' behind this. Maybe something in the ShellSol D70, maybe in the magnesium he used or even in some of the other chemicals. It might be that we even need more info from Pok himself. Maybe he should try with another batch of magnesium metal.

Anyway, I have an order outstanding at Kremer right now for 1 liter of ShellSol D70. Hopefully they dispatch at the start of next week and then I migt have the stuff next weekend. Shipping times usually are two to four days from Germany to the Netherlands.




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[*] posted on 11-12-2010 at 13:08


Quote: Originally posted by woelen  
Yes, up to now I assume that Pok is honest. It might be that he won the 'jackpok' but if that is the case then it is a job for us (and him) to find out what is the 'hidden luck' behind this. Maybe something in the ShellSol D70, maybe in the magnesium he used or even in some of the other chemicals. It might be that we even need more info from Pok himself. Maybe he should try with another batch of magnesium metal.

Anyway, I have an order outstanding at Kremer right now for 1 liter of ShellSol D70. Hopefully they dispatch at the start of next week and then I migt have the stuff next weekend. Shipping times usually are two to four days from Germany to the Netherlands.


Oh, I thought you'd run this one with Shellsol. Mine got here today (just a few days from Germany to Ole'Blighty). I'm just waiting for one or two more components... Next WE should be my 'Big Day', LOL...
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shocked.gif posted on 11-12-2010 at 13:48
I DID MAKE SOME POTASSIUM!!!



I have had the whole setup in the sand bath cool down completely and I found it was time to cleanup the mess. I added some water to the paraffin oil with the sticky goop inside which is mostly white, but also contained some remains of unreacted magnesium. I was met with a crackling and roaring noise as soon as water went into the test tube and bubbles of gas were produced. I decided to allow the concentration rise somewhat by pressing my thumb on the open end of the test tube and wanted to light the gas with a cigarette lighter, just testing for hydrogen. Suddently, while I still had my thumb on the open end of test tube, the gas mix above the oil exploded :o and immediately after the explosion there was a fairly strong underpressure. Luckily the test tube did not crack and I did not drop it! My heart skipped a few beats :o

After I recovered ;), I took the test tube (it still made a crackling noise) and swirled it somewhat and suddenly a 5 cm long pinkish flame erupts from the test tube and a WHOOP sound is produced. My heart skipped another beat ...

This kind of behavior can ONLY be explained by assuming that some potassium is formed. It only is a minute quantity and it is not formed in the form of nice globules, but definately some potassium is formed. The potassium reacts with water, giving hydrogen gas and when the liquid is swirled, then potassium at the liquid/air interface can form very hot spots, capable of igniting the hydrogen air mix above it.


The second experiment with the test tube above a flame of a propane torch indeed did not make any potassium. So, high temperature and fast reaction is not favorable. Slow reaction in a sand bath is one requirement for making potassium.


[Edited on 11-12-10 by woelen]




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[*] posted on 11-12-2010 at 13:49


Congratulations , woelen!
This is truly a breath of fresh air in this huge thread!
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[*] posted on 11-12-2010 at 13:57


Yes, this result certainly gives hope for better results. The potassium I had must have been very finely dispersed and mixed with the white material and unreacted magnesium, but at least it is proven now that this reaction indeed can make potassium. It might be that the ShellSol D70 allows better coagulation of potassium into larger spheres. The oil I used is quite viscous, the ShellSol is much more like water and that might help.

Let's see what blogfast's results will be when he has all the reactants. I'll try tomorrow with Mg/Al and (hopefully) next weekend with ShellSol D70.




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[*] posted on 11-12-2010 at 14:22


Spurred by woelen, I too added water to the white/grey sludge left after my previous attempt (photos I displayed earlier). The water sank to the bottom and after swirling around I too was greated with a very effervescent reaction which eventually caused the whole mixture to heat up very quickly and boil (picture attached). No actual flames but not what I was expecting

Now to pour some cold water on everything, I have had Shellsol D70 busily refluxing with Mg turnings and tert-butanol for 3 hours and no potassium beads. I will see what happens when everything is coll and I add water.

I too still have some hope but there is still something missing

IMG_4928.jpg - 33kB

IMG_4927.JPG - 40kB

[Edited on 11-12-2010 by plastics]
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[*] posted on 11-12-2010 at 18:25


Quote: Originally posted by woelen  
I added some water to the paraffin oil with the sticky goop inside which is mostly white, but also contained some remains of unreacted magnesium. I was met with a crackling and roaring noise as soon as water went into the test tube and bubbles of gas were produced.
Congratulations on the result. Very exciting.

Something you said reminded of a post-reaction workup, which isn't in the patent but might be useful during this experimental stage of progress. I thought well of blogfast25's comment about using a viscosity modifier, but had no ideas at the time. Combining these two, I suggest a workup with heptane.
&nbsp;&nbsp;&nbsp;&nbsp;Melting point of potassium = 63.38 &deg;C
&nbsp;&nbsp;&nbsp;&nbsp;Boiling point of heptane = 98.42 &deg;C
The idea is that you might use a viscosity modifier in a workup phase rather than in a reaction phase. Rather than adding water, add heptane, and put the vessel back under reflux at a lower temperature. The heptane, at much lower molecular weight, should dramatically reduce the viscosity, and thus also the energetic balance that would otherwise favor surface energy in potassium. There's also an activation energy for getting two potassium boundaries to merge, and heating under reflux could provide that. Furthermore, the alkoxides should be more soluble in heptane, dissolving off some of the surface contamination from K globules that interfere with them merging.

It's possible that heptane might be useful in the reaction phase, either with no ill effect or with positive effect. If the overall reaction is limited by alkoxide transport, then adding heptane would increase solubility and hence also its mobility. On the other hand, since the heptane would also be in reflux at the reaction, it would also tend to deposit alkoxide near the evaporation surface, leading to stratification if nothing were done to counteract it. So it's worth trying, but for present I can only recommend it in workup, given the large number of process parameter we don't understand yet.
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[*] posted on 12-12-2010 at 01:06


Woelen, how difficult was the "gunk" to remove from the test tube? This is merely a question to do with potential cleanup problems.



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[*] posted on 12-12-2010 at 07:20


Yes, that’s exciting indeed! I wondered why woelen hadn’t tested his gunge by now...

Watson’s idea of a work up with a lower viscosity solvent is very reminiscent of example 2 in the patent: sodium from NaOH. There the original solvent Shellsol D70 is removed after reaction and metal recovery carried out with dioxane (1,4-dioxacyclohexane), a low viscosity, low BP (101C) solvent. It's also polar and possibly a better solvent for alkoxides.

I’m pretty convinced that woelen’s Mg was far from ideal for this purpose: 65 to 100 micron is very fine compared to pok’s material. It’s possible that very fine K is formed with woelen’s stuff and that these fine droplets have a hard time coalescing into larger ones, isolated as they are by reagents/debris.

My own Mg seems much closer to pok’s: just about sub mm filings (but reagent grade purity).

What would also be interesting to do as a side show is to verify whether or not t-butanol reacts with KOH. For instance take a ration of 1 mol/0.5 mol t-butanol/KOH and heat it in test tube on a steam bath. Does the KOH dissolve? That would be evidence of t-BuO K forming…


[Edited on 12-12-2010 by blogfast25]
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[*] posted on 12-12-2010 at 07:49


@MJP: The gunk can easily be removed. Just let it soak in water and then rinse with some dilute HCl. It then is gone in minutes.


@blogfast: I also realize that my Mg may be too fine for this purpose. I do have filings, but these, on the other hand, are very coarse with a size of 5 mm and a thickness of 1 to 2 mm. I unfortunately have no block from which I can easily file something and crushing my filings to something smaller is very difficult. The big filings are too coarse, the powder is too fine.





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[*] posted on 12-12-2010 at 10:14


Quote: Originally posted by woelen  
@blogfast: I also realize that my Mg may be too fine for this purpose. I do have filings, but these, on the other hand, are very coarse with a size of 5 mm and a thickness of 1 to 2 mm. I unfortunately have no block from which I can easily file something and crushing my filings to something smaller is very difficult. The big filings are too coarse, the powder is too fine.



Between a rock and a hard place...

And sod it, I’m going to have a go tomorrow. I’ve put together my ‘apparatus’ today. My main problem is that I only have 2-methyl-2-butanol, a tertiary alcohol but not t-butanol.

My experiment will be close to pok’s (same scale but with injection of the alcohol straight into the mix, and using an equivalent amount of 2-methyl-2-butanol). I’ve been messing with a sand bath to find a (gas) setting that takes the reactor slowly to 200C and beyond. I’m as ready as I can be with a bit of a plan to investigate any resulting gunge properly.

Below the ‘magical ingredient’, Shellsol D70. It really is remarkably odourless:


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[*] posted on 12-12-2010 at 13:04


@Blogfast25: To answer your question why I didn't do the check with water earlier, the answer is simple. The goop that I obtained did not look promising at all. It is a somewhat slimy white/grey goop with unreacted magnesium in it. No nice globules of K-metal. Hence I did not expect any interesting properties of this material.


------------------

I also did the experiment with Mg/Al now instead of Mg. Again I used a powder, particle size at the order of magnitude of 50 um, even finer than my magnesium. I don't have anything else, remember this stuff is intented for pyrotechnics purposes such as glitters and flares.

The reaction with Mg/Al is more vigorous than with Mg alone. At times the liquid started foaming up and white smoke erupted from the liquid. Luckily, the reaction never became so violent that foam went into the thin tube. In this experiment, indeed no K-metal is formed at all. After cooling down after a 2 hour period at 200 ... 250 C I added water. No reaction at all. Shaking also did not result in an interesting reaction. The white material just is a mix of Al(OH)3 and Mg(OH)2 or oxides of Al and Mg. Nothing interesting.

For now, I'll skip the experiments with the Hg. It is clear that K-metal is formed, but now we need to find the conditions for formation of easy to separate beads of K-metal.

-----------------------------------------------------------------

I have a source of very coarse reagent grade Mg powder (250 um particles, more or leass spherical). What do you think of that? Would that be suitable? I did not yet order it, minimum amount is 1 kg at around EUR 25 including the price of shipping. This is a decent price, but what must I do with 1 kg of Mg-metal if I it is not useful for making K-metal?




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[*] posted on 12-12-2010 at 13:37


Quote: Originally posted by woelen  
I have a source of very coarse reagent grade Mg powder (250 um particles, more or leass spherical). What do you think of that? Would that be suitable? I did not yet order it, minimum amount is 1 kg at around EUR 25 including the price of shipping. This is a decent price, but what must I do with 1 kg of Mg-metal if I it is not useful for making K-metal?


Srtange of the magnalium yielded nothing. The coarser Mg may work better, who knows what in this riddle/puzzle?!?
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[*] posted on 12-12-2010 at 21:47


Impressive work. I'm amazed this can be done in such a straightforward fashion.

I might try this with ACS grade Tetralin rather than Shellsol D70. I only got t-amyl alcohol at the moment, hopefully it'll be compatible.

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[*] posted on 13-12-2010 at 03:53


Quote: Originally posted by blogfast25  
Watson’s idea of a work up with a lower viscosity solvent is very reminiscent of example 2 in the patent: sodium from NaOH. There the original solvent Shellsol D70 is removed after reaction and metal recovery carried out with dioxane (1,4-dioxacyclohexane), a low viscosity, low BP (101C) solvent. It's also polar and possibly a better solvent for alkoxides.
I reread the patent. I have said above that workup isn't in the patent, which isn't quite right. They do have a single, one-sentence paragraph in their narrative which says "alkali metal [...] may be separated", but don't stress the workup. The examples do have workup. Ex. 1 and 2 have workup with vacuum distillation and 1,4-dioxane, ex. 4-6 by filtering through a frit, and ex. 3 has no workup.

In both of the solvent workup examples, the initial Shellsol solvent is first filtered off by vacuum distillation (1 torr in the first example, 15 torr / 120 &deg;C in the second). Example 2 does explicitly state "when the sodium has the desired particle size", presumably because tiny particles are merging. On the other hand, example 1 says "the potassium rises to the surface [of the dioxane] and is communited by stirring to form spheres of suitable size". Communited means "made smaller", which happens only after K "rises to the surface". Is there an innuendo here that potassium beads are merging together as it rises? When they say that stirring breaks up the potassium, I infer that vigorous mechanical agitation is sufficient to keep K particles small. So agitation from vigorous boiling itself may initially produce small particles of K. If this is the case, then reflux at a lower temperature, with less agitation, may induce merging. I imagine that centrifuging would cause merging as well.

I suggested heptane because (1) it is readily available (as Bestine rubber cement thinner), (2) it is in the same saturated alkane class as the solvent, and (3) it has a boiling point higher than that of potassium. It should be miscible with the reaction solvent, alleviating the need for vacuum distillation. I doubt it works as fast as vacuum distillation and a more polar solvent, though. I'm now thinking that using heptane at slightly beneath its boiling point, but above the melting point of K, would eliminate agitation from bubbling. Gentle kneading with a glass rod or the like might help coalesce K particles. I admit this is mechanically problematic to knead under inert atmosphere.
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[*] posted on 13-12-2010 at 03:58


I'm glad that you've done it, woelen.

About the Mg size: At the photo you can see the Mg I used. It looks coarse (scale is in cm - so about 200µm broad), but these are mainly rolls of very thin (maybe < 50µm thick) Mg "foil" - an effect of filing. So if you use 20-50µm spherical Mg powder or so I think this should be the best size. I'm pretty sure that only 2 Mg properties will effect the outcome: surface area (depends on particle size) and purity (98%-100%).

@ woelen: did you also see small flashes of light (besides the explosion noise) when you added water to the mix? At least at 0.5mm K balls I always observed light flashes when I cleaned the erlenmeyer with water after the experiment. Maybe in your experiment the K was too much dispersed and too small to produce light flashes.

An advantage of a larger reaction volume (e.g. 50ml) is, that failures like income of some oxygen or loss of tert.butanol can be accepted up to a certain amount. But if the same amount (for example due to an equally large hole in your balloon or elsewhere) affects 5ml reactions the relative effect would be 10 times higher. Larger scale also is easier to handle (for exampe: stepwise addition of t-butanol within 30 min might be difficult if your total t-butanol is 0.6ml). But you obviously showed that even in small scale the experiment gives potassium.

I will repeat the synthesis as well in the next time to see if it still works as in the past. If it works, I will try to make Cesium as described in the patent. Making the needed dry CsOH may even be more difficult (for me) than making Cesium from it :D.



[Edited on 13-12-2010 by Pok]
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[*] posted on 13-12-2010 at 04:16


Quote: Originally posted by NurdRage  
I might try this with ACS grade Tetralin rather than Shellsol D70. I only got t-amyl alcohol at the moment, hopefully it'll be compatible.
Example 3 in the patent uses preformed t-amyl alkoxide (called "tertiary amylate" there). Given Nicodem's comment above, it should be readily formed from KOH and t-amyl alcohol in alkane solution.

As far as tetralin, the same example 3 uses decalin as a solvent, the completely saturated version of tetralin, itself the half-saturated version of naphthalene. Shellsol D70 is hydrogen-treated to remove aromatics and alkenes; it has little unsaturated content. I have strong suspicion that somehow this is significant, although I have no particular mechanism to explain why. It might act as a hydrogen scavenger, forcing a side reaction. Double bonds might significant change solvation energy, or preferentially solvate some species and reduce its reactivity.

I'm all in favor of exploring the parameter space of this reaction, but at the current stage of maturity, I wouldn't take failure with this solvent as anything like determinative.

On the plus side, the boiling point of tetralin is a bit higher than that of decalin, which will make the reaction faster. Tetralin as a boiling point right around the lower boiling point of Shellsol D70. That of decalin is in the range of Gamsol, which is easily available and inexpensive in the US.
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