Sciencemadness Discussion Board

Make Potassium (from versuchschemie.de)

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MrHomeScientist - 17-4-2013 at 06:00

I think he's just upset this reaction can't be done with bleach and vinegar. He needs a title like Anders...




I did another run yesterday, using lower-boiling (~210C) Tiki torch fuel. It supposedly contains citronella but is colorless, unlike the yellow stuff you usually find. The hope was that this would give more agitation from boiling, but it didn't really seem to make a difference. I'm starting to think my thermocouple in the sand bath is reading a much different temperature than what's in the reaction flask, despite me placing it right outside the flask.
Fairly routine reaction overall with little difference to my other runs - I'll inspect the products sometime in the next few days.

blogfast25 - 17-4-2013 at 10:34

Quote: Originally posted by watson.fawkes  

I think it's time to stop feeding the trolls.


Agreed.

EC1: he's unlikely to accept you as an unbiased experimenter.

Interestingly, there's a US Patent (1,978,647) that describes the preparation of anhydrous, relatively pure (free of hydroxide) Na or K alkoxides from the alkali metal hydroxides. Reaction of the MOH with an excess of the target alcohol, followed by precipitation of the anhydrous alkoxide by mixing in anhydrous acetone. Sounds very doable. The 'Organics' contributors seem to swear by it...

[Edited on 17-4-2013 by blogfast25]

MrHomeScientist - 17-4-2013 at 10:43

Quote: Originally posted by AJKOER  
OK, no I am not upset, in fact, I am laughing hard.

But, I understand a good many of the followers on this thread worship at the altar of Magnesium as a great reducer or something. It does have a lot of blinding flash, I give it that.

So it doesn't matter that I have revealed your prophet is a follower of someone who is even more clueless than the original author of the background patent (blasphemy, I know).

The amount of ridiculousness you are willing to accept to preserve your false Mg god is inspiring (in plain view of patent inconsistencies on how it could ever work, other peer reviewed research noting the power of Mg in CH3OH, a known creator of an active form of H2, not Mg, that I referenced (some little known chemical journal), but excuse me while I laugh, and laugh, and laugh, after all, you have your 'authority' (but, may I dare recommend, that you teach him how to balance and write at least two full equations).

And, do want to see magic? Cut your Mg dose in half (relative to KOH and ROH) and your false god is totally revealed. But none of you will, you are devout mindless followers. It would be simply too irreligious, unthinkable.

But today is a new day, any more funny explanations (I noticed how you skipped over the small issue of K not reacting at all with water, vow, you are a true devotee). I know, I feel bad, I shouldn't make fun of people with mindless convictions, so I just leave now and laugh privately.

I would recommend, however, that this thread be moved to Organic Chemistry section. They have the right to know that you are making fun and discounting one of their gods - Hydrogenation (something about a Noble prize in Chemistry). Like we could have a 100 year religious war or something (wait, we have already had one of those).
[Edited on 17-4-2013 by AJKOER]


This post is the perfect example of the defeated "internet arguer." "Laughing" at our supposed ignorance, claiming someone's theory is "religious," and offering no real input of your own are the hallmarks of a bad (some might say trolling) post.

If you are so adamant about it, please conduct the experiment you propose. You can't really demand that we persue your own personal theory. We were all able to get the chemicals, and so can you. Don't be an armchair chemist - anyone can balance equations in a vacuum, but the real value is testing things in real world conditions. Personally I'd love to see more data about this reaction. Currently I'm focusing on improving coalescence in my product, rather than exploring alternative hypotheses. I want to get the process down properly before branching out.

I recommend this whole chain of posts (including this one) be sent to detritus. It's clogging up an already tremendously long thread.

blogfast25 - 17-4-2013 at 12:06

We'd all like to see more data about this reaction, Mr HS, but they're unlikely to pop up real soon, considering the resources needed for just one run.

I've just found some isoamyl alcohol (3-methyl-1-butanol, the longest chain alcohol I've got in my larder), very dry, so I might try that patent to synthesize the potassium alkoxide from that...

[Edited on 17-4-2013 by blogfast25]

Nicodem - 18-4-2013 at 11:34

WARNING: I don't want to hear another word about "nascent hydrogen" here!

The next member that tries to troll in this thread with such crackpot ideas will be sanctioned by posting-right suspension.

Is it possible that nobody noticed this thread already has 53 pages of posts, many of which are utterly unnecessary? The last thing we need here is to feed trolls that come out with baits as idiotic as "nascent hydrogen".

I invested a lot of work to split of the dozens of these posts by AJKOER and replies to him. I'm sure I made some injustice to some replies that may have contained other information and some of the posts left here clumsily refer to split off posts, but it is certainly better this way. I left the trolling thread active in Whimsy so that those who like to feed AJKOER can do so without harm to the scientific part of the forum.

bfesser - 18-4-2013 at 14:36

Thank you for all your hard work, Nicodem. It's appreciated.

AJKOER - 18-4-2013 at 14:41

First a review of my take on how the overall reaction is proceeding.

Aqueous phase since as much as 27% of KOH could be water:

Mg + 2 KOH + H2O --> [K2MgO2 + H2O] + H2* (g)

K2MgO2 + H2O <---> 2 KOH + MgO

Net:
Mg + H2O --KOH--> MgO + H2* (g)

Non-aqueous reaction:

KOH + ROH --> ROK + H2O

Mg + H2O --KOH--> MgO + H2* (g)

ROK + 1/2 H2* <---> ROH + K (s)

Net:

KOH + H2O ---> MgO + K (s) + 1/2 H2*

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

Comments: Per Wikipedia (http://en.wikipedia.org/wiki/Tert-Butanol ), to quote:

"For example, the commonly used organic reagent potassium tert-butoxide is prepared by refluxing dry tert-butanol with potassium metal.[5]

K + tBuOH → tBuO−K+ + 1/2 H2

The tert-butoxide species is itself useful as a strong, non-nucleophilic base in organic chemistry."

So, what I am postulating here is that activated hydrogen is formed (most likely via chemisorption, discussed more below) and that with excess H2* (from the initial dehydration) and also pressure (balloon employment) the ROK formation reaction is reversed to some extent:

ROK + 1/2 H2* ---> ROH + K (s)

Now, more on this chemisorbed hydrogen most likely created via the presence of MgO. Here is an abstract (source: "H2 chemisorption and consecutive UV stimulated surface reactions on nanostructured MgO", in Phys. Chem. Chem. Phys., 1999,1, 713-721 (link: http://pubs.rsc.org/en/Content/ArticleLanding/1999/CP/a80844... ). To quote from the abstract:

"MgO nanoparticles obtained by chemical vapour deposition (CVD) were exposed to H2 and subsequently to UV irradiation and/or molecular oxygen at room temperature. A combined IR/EPR study reveals the role of low coordinated surface sites and anion vacancies in the diverse reaction steps. The hydride groups emerging from the initial H2 chemisorption processes (heterolytic splitting) play an active role in the consecutive reactions. They provide the electrons which are required for the UV induced formation of surface colour centres and for the production of superoxide anions (redox reaction). Both the colour centres and the superoxide anions are EPR active. The hydroxy groups resulting from H2 chemisorption do not actively participate in the consecutive reactions. Together with the OH groups formed in the course of colour centre formation they rather play the role of an observer. They undergo specific electronic interactions with both the colour centre and the superoxide anion which are IR inactive (or IR inaccessible) surface species. They may, however, be observed by IR spectroscopy via the specifically influenced OH stretching vibrations. This proves the intimate interplay between IR and EPR spectroscopy as applied to the surface processes under investigation. As a result, two paths were found for the three consecutive surface reaction steps: H2 chemisorption, colour centre formation and superoxide anion formation. In the first one a single, well defined surface area element is involved, namely a low coordinated ion pair, the cation of which is a constituent of an anion vacancy. In the second path a diffusion controlled intermediate step has to be adopted in which the electron required for the colour centre is transported by an H atom travelling from a hydride group to a remote anion vacancy. In either case there is clear experimental evidence that the finally resulting superoxide anions are complexed by the colour centre cations."

See also "Theoretical aspects of H2 and CO chemisorption on MgO surfaces", Surface Science (May 1982), 117 (1-3), pg. 571-580 at http://journals2.scholarsportal.info/details.xqy?uri=/003960...
to quote from the abstract:

"Preliminary ab initio calculations at the SCF level and beyond are reported for the chemisorption of H2 and CO at the (001) surface of MgO. It is concluded that the dissociative chemisorption of H2 requires the presence of defects and that at anion vacancies, V− centres and self-trapped holes the overall process is exothermic in each case. It is predicted to be non-activated at anion vacancies and possibly the same at the other two defects. Binding energies are calculated for the interaction of CO with a non-defective (001) surface of MgO and at impurity ions therein. They range from 2.5 kcal/mole at Al3+ to 20.8 kcal/mole at Cu2+ and are shown to be highly sensitive to lattice relaxation of the defective surface."

where there is an interesting reference to the role of impurities in the MgO.

Now, there are also so studies citing the reaction of between hydrogen and magnesium, but mostly as fine Mg powder (or nano). However, Mg surface attacked by KOH, may be more amiable to H2. Probably, an important speculation is that absence MgO, no or reduced chemisorbed H2 formation, no reduction reaction and no K is produced! Also, less than completely pure Mg, KOH or KOH, could produce detective surfaces on the MgO, increasing yield.

I would speculate that MgO dust on Mg turnings may provide a good contact point for gaseous H2 and, with infrequent stirring to add ROK, help to form potassium. Neither frequent or very infrequent (in agreement with the patent instructions) would be advisable.

Now why is Mg dust no good for this reaction? My speculations, first, the reaction rate would be too fast (also more heat) and limit gaseous contact. Also, absence the Mg turnings, less support for formed MgO thereby limiting the H2 contact.


[Edited on 19-4-2013 by AJKOER]

AJKOER - 18-4-2013 at 17:03

So What Happens with Reduced Mg Input (or too much water)?

So for the non-aqueous reactions, we double the 1st equation to increase the water, and leave the magesium & water equation unchanged:

2 KOH + 2 ROH --> 2 ROK + 2 H2O

Mg + 2 H2O ---KOH---> MgO + H2O + H2* (g)

2 ROK + H2* <---> 2 ROH + K (s)

Net:

2 KOH + Mg ---> MgO + H2O + K (s) --> MgO + KOH + 1/2 H2 (g)

In other words, possibly zero yield on the potassium assuming full mixing occurs.

Interestingly, this result is not predicted by Blogfast (a suggested test of paths).



[Edited on 19-4-2013 by AJKOER]

Substitutes for Mg (MgO)?

AJKOER - 19-4-2013 at 14:08

Based on my presumed reaction mechanisms, are there any potential substitutes for Mg? To answer, I refer to Wikipedia on chemisorption (link: http://en.wikipedia.org/wiki/Chemisorption ), to quote:

"Due to specificity, the nature of chemisorption can greatly differ, depending on the chemical identity and the surface structure."

So, the apparent answer is there is, indeed, something special about Mg (MgO) and potential substitutes would be hard to come by.

Research appears to indicate, however, that Al2O3 with SiO2 and Fe may be a candidate fulfilling part of the requirements. This is based on a review of some related research, for example, "Connection between Chemisorption Kinetics and Adsorption Equilibria of Organic ompounds on Oxide Surfaces†", link (full paper is available): http://oscar.chem.ccu.edu.tw/~wugol/references/afile/Langmui... To quote from the paper:

"The Bronsted and Lewis acid-base sites are the main types of active sites on SiO2, TiO2, Al2 O3, and other pure and mixed oxide surfaces in different chemisorption and catalytic transformations of organic compounds. The kinetics of organic reactions with OH groups of a silica surface is one of best investigated cases among these oxides.1,2 It was established that one occurs through two main mechanisms, namely, electrophilic substitution of hydrogen of this group by organic residue (SEi) and nucleophilic substitution of OH groups by this residue (SNi(Si)). Formation of precursors (linear hydrogenbonded or cyclic donor-acceptor complexes between organic molecules and surface groups) have been proposed in the first stage of these reactions.1,2 Of course, total activation energies, rates, and selectivities of surface reactions strongly depend on the precursor stability."

Another work, "Hydrogen Chemisorption on Al2O3-Supported Gold Catalysts" published in "J. Phys. Chem. B, 2005, 109 (30), pp 14581–14587, Copyright © 2005 American Chemical Society. To quote from the abstract:

"Hydrogen is dissociatively adsorbed on the gold particles in Au/Al2O3 catalysts, as demonstrated by a combination of in-situ X-ray absorption spectroscopy, chemisorption, and H/D exchange experiments. This chemisorption of hydrogen induces changes in the Au L3 and L2 X-ray absorption near-edge structures. The gold atoms on corner and edge positions dissociate the hydrogen, which does not spill over to the face sites. Therefore, the average number of adsorbed hydrogen atoms per surface gold atom increases with decreasing particle size. With temperature, the hydrogen uptake by supported gold increases or remains constant, whereas it decreases for platinum. Furthermore, in H/D exchange experiments, the activity of Au/Al2O3 increases strongly with temperature. Thus, the dissociation and adsorption of hydrogen on gold is activated."

"Chemisorption of hydrogen on aluminum oxide", published by Bulletin of the Academy of Sciences of the USSR, Division of chemical science, January 1971, Volume 20, Issue 1, pp 148-149. From conclusions, to quote:

"1. A highly pure Al2O3 sample, degassed at 500°, does not chemisorb hydrogen. The absorption of microamounts of hydrogen was observed after degassing at 800–900°.
2. The amount of absorbed hydrogen increased 10-fold when the amount of iron impurities in the Al2O3 was increased from 10−7 up to 10−3%."
---------------------------------

So, impure Al2O3 with SiO2 and Fe impurities may fill the chemisorption requirement. But, it is known that the reaction of Al and H2O is very slow unless accelerated with a little I2, which may be unnecessary as the KOH is expected to attack the Al. My expansive take, nevertheless, on this particular Iodine acceleration reaction with Aluminum, if employed, as to be aware of other possible side reactions:

Al + 3 I2 --> 2 AlI3

but, in the presence of water, a hydrolysis occurs:

2 AlI3 + 6 H2O --> 2 Al(OH)3 + 6 HI (see http://en.wikipedia.org/wiki/Aluminium_iodide )

removing some water. Also, with the newly created HI:

2 Al + 6 HI --> 2 AlI3 + 3 H2 (see Wiki same link)

or, for all three reactions the net reaction is:

4 Al + 6 H2O + 3 I2 ----> 2 Al(OH)3 (s) + 3 H2 (g) + 2 AlI3

and, upon adding 6 more H2O to each side:

4 Al + 12 H2O + 3 I2 ---> 4 Al(OH)3 (s) + 3 H2 (g) + 6 HI

and adding 2 more Al to each side:

6 Al + 12 H2O + 3 I2 ---> 4 Al(OH)3 (s) + 6 H2 (g) + 2 AlI3

Note, the process can be repeated, but the quantities '3 I2' and '2 AlI3' will remain constant while the amount of Al and H2O increase. As such, the Iodine acts essentially as a catalyst (only a small amount is required to initiate the reaction regardless of the amount of water, and only that initial Iodine is consumed). This analysis can also suggest the amount of excess Aluminum to employ to remove any water presence from the alcohol (my calculations are 2/3 moles Al are needed to be added for each estimated moles of H2O to be removed). Also, note that when all the water is consumed, the chain breaks and the initial number of moles of Iodine added is now 2/3 as many moles of AlI3.
-------------------------------

So a possible substitute for Mg would be to add impure Al ( Aluminum foil) sufficient to process all water in the aqueous and non-aqueous phase with a little I2 which may be unnecessary as the KOH is expected to attack the Al. At the completion of the 1st phase, add Al2O3. Issues not addressed include possible interaction of the small amount of Iodine and alcohol, best reaction temperature, and the expected loss in efficiency (reaction time) of the chemisorption employing Al2O3 in place of MgO. An obvious solution: replace Al2O3 with the addition of prepared MgO from the dehydration of inexpensive Mg(OH)2.

Overall, assuming their is some validity to my speculated reaction path, I would suspect that this could be an even more problematic synthesis than with Magnesium, but replacing Mg with Al foil (perhaps a touch of I2), and prepared MgO (form say MgSO4), may significantly reduce material accessibility and cost requirements.


[Edited on 20-4-2013 by AJKOER]

blogfast25 - 20-4-2013 at 04:56

AJ, you'll never learn. No doubt your latest nonsense will soon be pruned onto your new whimsy thread, so why not post this stuff directly there? No one's taking a blinding bit of notice here and they won't there either. You'd save Nicodem time and effort.

You're now officially acting in bad faith.

AJKOER - 20-4-2013 at 05:49

Blogfast:

Some background on what has occurred to date.

> I was put a whisper thread. I re-summarized and place my understanding solely on the whisper thread of what I believe is going on citing with references to recent peer review work (not solely personal opinion or unsourced patent references).

> My whisper thread was apparently being placed on the main thread (for a time, this was unknown to me, or as to how this was occurring).

> I sent a U2U to Nicodem to bring the matter to his attention. I also requested, at his discretion, to remove my material on the main thread, and replace a link to the whisper thread for those interested in a documented alternative hypothesis. I also stated to him that in spite my impeccable sources, some may find my material undigestible based solely on presenting an alternate opinion as to reaction mechanism. As such, I told Nicodem that he could use this alone as justification, with my consent, to move my material again.

So far, however, in spite of your apparent attempts to crush documented based alternative hypotheses, I am still here for now. The good news for you as pending future experimental results, I probably have little added material to add. So barring U2Us to comment otherwise, please feel free to present your personal opinion, sources (or lack thereof if you so wish) and any logic (or none) as I for one, promise, not to comment unless you explicity ask me or materially mispresent my hypotheses, and then, my replies will be sourced based responses only.


[Edited on 20-4-2013 by AJKOER]

blogfast25 - 20-4-2013 at 07:50

Quote: Originally posted by AJKOER  

So far, however, in spite of your apparent attempts to crush documented based alternative hypotheses, I am still here for now.


Next you'll invoke 'freedom of speech', idiots of your variety always do, sooner or later.

There's nothing to 'crush' here. There are no 'alternative hypotheses' being presented that are worth reading. Stick the rest of your nonsense where it belongs: in whimsy, NOT HERE.

The alternative is to keep posting it here, where no one will read it and all you'll achieve is to further alienate people and to what good? To have the last word?

[Edited on 20-4-2013 by blogfast25]

Mailinmypocket - 20-4-2013 at 08:27

I miss how this thread used to be up until a short time ago- with experiment results and ideas, pictures and discussions of successes and failures, you know, all that good stuff... :(

blogfast25 - 20-4-2013 at 09:42

MIMP:
Well, we’ve recently seen another 2 member making potassium, so that’s quite positive. I’m sure we will see others follow suit.

Personally I’d like to see some more activity on the possible synthesis of other tertiary alcohols, as per this thread:

http://www.sciencemadness.org/talk/viewthread.php?tid=15171

But t-alcohols aren’t so easy to produce and unfortunately they are the only ones likely to work here.

woelen - 20-4-2013 at 12:03

:mad:

@AJKOER: Didn't you notice how utterly annoying you are? People have asked you to stop adding more and more nonsense, but you seem unstoppable. I suspended your account. After 2 weeks you'll be able to post again. I really do not like this kind of heavy handed moderation, but unfortunately I see no other way to stop this annoying behavior.

elementcollector1 - 23-4-2013 at 20:52

You know what would be interesting? What if I ran this reaction with calcium instead of magnesium metal? That would be a novel contribution (although not necessarily welcome to the home chemist, given the availability of calcium metal vs. magnesium metal).

woelen - 23-4-2013 at 23:31

Experimenting is always welcome. Although calcium is less widely available than magnesium, it is interesting to see how it behaves. I do expect though that you need small granules of calcium and the use of bulk material probably will not lead to acceptable reaction rates.

Pyro - 26-4-2013 at 12:18

How would one go about making small Ca granules from large chunks? A while ago on a warm dry day I used metal cutters to cut part of mine up into 5x5x4mm pieces, I can't realistically get smaller than that.
Would that be small enough?
Ebay has some good prices for Ca, I picked up 100g for 12eur.

blogfast25 - 27-4-2013 at 04:57

Chips, shavings or shavings also work for Mg, so they might for Ca. But Ca is harder to obtain and tarnishes quickly in air, enormous drawbacks for the hobbyist. Very much worth trying for those who have it though...

Pyro - 27-4-2013 at 05:20

but how will I make them?
http://www.benl.ebay.be/itm/CALCIUM-METAL-TURNING-AND-DENDRI...
i bought mine here

[Edited on 27-4-2013 by Pyro]

blogfast25 - 28-4-2013 at 05:15

Quote: Originally posted by Pyro  
but how will I make them?
http://www.benl.ebay.be/itm/CALCIUM-METAL-TURNING-AND-DENDRI...
i bought mine here

[Edited on 27-4-2013 by Pyro]


That's quite a reasonable price.

Size reduction would have to be carried out under argon or under oil. It can be cut just about with a knife (acc. Wiki). Perhaps a small, dedicated food processor or smoothie maker could be used? Load oil (kerosene) and metal, zap for some time and separate fines from coarser material using a sieve. A calcium/kerosene smoothie, yum!

Then add catalyst and KOH and apply the procedure. Be a trailblazer! :cool:


[Edited on 28-4-2013 by blogfast25]

Pyro - 28-4-2013 at 08:23

Nope, No way! it's bloody hard. I needed to put all my weight on the clippers to cut it. I would say it's harder than lead, a bit softer than copper or something like that.

elementcollector1 - 28-4-2013 at 21:36

Really? I had to use a hacksaw to cut through mine, no idea that it could be cut with a straight blade.
Have I mentioned how difficult it is to hacksaw through a 1 cm round lump?

blogfast25 - 29-4-2013 at 05:59

Pyro:

That hard, eh? Try grinding it with a mortar (and oil). But it's probably too soft for that... :(

EC1: seems your hacksaw and pyro's experience are in agreement.

But if it's sufficiently hard it should be obtainable as powder too...

It would be a real coup if someone could pull this off with Ca instead of Mg. Thermodynamically KOH + Ca == > K + CaO + 1/2 H2 is certainly favourable, at least that's something!


[Edited on 29-4-2013 by blogfast25]

elementcollector1 - 29-4-2013 at 09:50

Still, if I could cut through them at all, that'd be nice.
What would a mortar and pestle do? I'd imagine nothing, the calcium is far too hard to be affected by such a blunt instrument. Maybe a hammer on a steel surface.

blogfast25 - 29-4-2013 at 12:28

Quote: Originally posted by elementcollector1  

What would a mortar and pestle do?


Hard and brittle things grind down well in a mortar and pestle. But I imagine Ca metal is too malleable for that. Ball mill grinding (see e.g. Al powder) could work but you need inert atmosphere.

It's probably possible to 'atomise' Ca the same way spherical Al is produced: by rapid cooling/solidifying of an aerosol of liquid Al. Not for us hobbyists, I'm afraid...

[Edited on 29-4-2013 by blogfast25]

blogfast25 - 5-5-2013 at 07:10

Yesterday I prepared some more potassium, this time with a scaled up and upgraded set up but the results weren’t as good as I had hoped for. I scaled up from 50 ml solvent to 150 ml solvent and used 2-methyl butan-2-ol as catalyst (adjusted for MW vis-à-vis t-butanol) and Shellsol D70 as solvent (I had no deodorised kerosene left, so used up most of my remaining Shellsol D70), here’s the setup:



So, a 250 ml flat bottom RBF, an oversized Allihn condenser (no cooling water or air but I had air on standby) and heated by a temperature regulated oil bath.

All in all it went very uneventfully although the sudden burst of hydrogen (early reaction of KOH water with Mg) was particularly violent this time and some white mist did manage to escape through the chimney, due I believe to mechanical entrainment by the sudden hydrogen flux.

Bath temperature settled first at about 207 C, then climbed steadily to nearly 220 C. I refluxed for about 4 hours, detail:



As at some point the solvent started to cloud over (due to fine MgO I think) so I couldn’t see any potassium globules being formed, until at the end after cooling to below 70 C this crap shoot shot showed them:



Once the solvent was removed it became clear though that coalescence this time had been quite sub normal, with only relatively few medium sized potassium globules ready for picking:



Checking the left over dark grey sediment (not shown) I found it to be mostly potassium fines and MgO. I found no residual Mg metal. Some of the MgO slag was very coarse, almost rocky, making further K recovery difficult, so I decided not to bother.

I believe that in this instance the lack of any stirring was partly to blame for the poor coalescence: this upgraded set up is too rigid to even swirl the flask occasionally. Absence of any stirring may also promote MgO agglomeration. Slow, steady stirring just to keep everything in motion is what I would recommend to any first time experimenter.

I also have been thinking for a while now that there must be a better way of harvesting the potassium than 3 hours of additional refluxing. I had found higher up that in the right conditions the actual reduction reaction seems to be over in about 1 – 2 h tops, judging by hydrogen evolution which tails off dramatically after about 1 h of refuxing. Checking hydrogen evolution periodically is of course easy: fill a test tube with the off gases that leave the condenser and check for hydrogen with a match, lighter or Bunsen.

After cessation of reaction, the reactor could then be cooled down to below 80 C, the supernatant solvent removed and replaced by fresh kerosene and this mixture of fines (MgO + fine potassium) treated much the way one pans for gold: here the lighter potassium will ‘travel’ further than the denser MgO (d = 3.58 kg/L). The relatively MgO free potassium should be fairly easy to coalesce at around 100 C.

Another observation (which I’ve made several times) is the following. One objective of this test was to explore the possibility of catalyst recovery/recycling. I’ve noticed many times that the supernatant post-reaction solvent, when decanted off and allowed too cool settles to a viscous, even jelly like material. The proposed reaction mechanism predicts that all catalyst is present in the solvent as the relevant potassium alkoxide, thus the solvent should in principle be recoverable without further to do.

Alternatively, treatment with acid should hydrolyse the potassium alkoxide to salt and the alcohol in question (but the alcohol is soluble in the solvent, of course). Today I checked the supernatant liquid that I had set aside and a whitish, jelly like precipitate had separated out. Could this be potassium 2-methyl butan-2-oxide? I’ve yet to decide what to do with it but there’s enough for two small scale tests.


Finally, another word of caution to those who are new (and old!) to handling potassium. Yesterday I very foolishly disregarded (probably due to tiredness and being in a hurry) the advice I dished out to ‘elementcollector’ and used methylated spirits, INSTEAD F A LOT OF ISOPROPANOL, to react away the fines. The ethanol immediately caught fire, the flame struck inside the small meths HDPE bottle and trying to douse the flames my hand caught fire. I managed to extinguish the fire on my hand quickly and managed also to place the cap on the bottle to deprive it of oxygen. That worked but caused some more burning meths to land on my hand. After extinguishing that too, a large glass beaker was put over the primary fire and that died down instantly.

My hand suffered no lasting consequences but it did hurt a bit for most of the evening. Today it’s fine without even a scar as a memento, although it’s definitely hairless!

So, please take great care in disposing of unwanted potassium and use a large amount of IPA, while stirring constantly and do it where you can’t set fire to anything.



[Edited on 5-5-2013 by blogfast25]

elementcollector1 - 5-5-2013 at 08:50

I should probably mention that when I thought I was using isopropanol, it turned out to be a weak solution of HCl that I had forgotten about.
This explains a lot.

blogfast25 - 5-5-2013 at 08:59

EC: even IPA isn't ideal because it's also flammable. But it's the lesser of evils compared to methanol, ethanol or water, especially with finely divided potassium.

MrHomeScientist - 6-5-2013 at 05:42

I don't like using isopropanol, personally - no matter what I do it always catches fire. In my last attempt I used a Petri dish full of IPA and dropped in very small spatula-fulls one at a time. Each time, there was a hiss, crackle, sparks, and ignition of the dish. Easy enough to blow it out, but still dangerous. In my experience, even if you use a lot of IPA to stop the potassium reaction from heating the liquid to its ignition point, the sparks produced still ignite the alcohol vapor floating over the surface.

Instead I just use a big bucket of water, halfway full, and pour in ~10mL at a time. It certainly doesn't like that, but at least water isn't flammable. If you don't fill the bucket up all the way and go slowly, nothing will splash out at you.

blogfast25 - 7-5-2013 at 06:34

I guess you're right, Mr HS, plain ole' water in copious amounts and away from flammable vapours is probably still best.

Vargouille - 7-5-2013 at 11:17

I was under the impression that potassium was quenched by adding it to dry hexanes/toluene, and then adding dry isopropanol slowly. The hexanes dilutes the isopropanol to keep the reaction from being too vigorous, as does the slow addition of the alcohol.

Toluene - 19-5-2013 at 14:39

Hello, I have a couple of questions: Did anybody try to use another alcohol as catalyst? I have already ordered my t-butanol ,but til it arrives I decided to take a look at household chemicals, I found an interesting alcohol:ethylenglycol (ethanodiol) I know it is not a three or more carbons alcohol so, my question is : should I give a try with the ethylenglycol or I'm just wasting my time?

Another question. I have read the whole thread and I saw that some people say that sodium might be reduced with aluminium did anybody try this?

elementcollector1 - 19-5-2013 at 15:04

There have been attempts with non-tertiary alcohols, but no successes with these so far. Only tertiary alcohols seem to work.

MrHomeScientist - 20-5-2013 at 06:00

If you've actually read the whole thread, then you'd know other alcohols have been tried with little success. The only other one confirmed to work so far is t-amyl alcohol, with others failing for various reasons. I posted a sort of "summary" of the thread back on page 51, I believe, if you don't want to actually read the entire thread. I just copied down posts that were relevant to my own experiments so it certainly leaves out a lot of information, but it's a start.

Toluene - 20-5-2013 at 06:33

Quote: Originally posted by MrHomeScientist  
If you've actually read the whole thread, then you'd know other alcohols have been tried with little success. The only other one confirmed to work so far is t-amyl alcohol, with others failing for various reasons. I posted a sort of "summary" of the thread back on page 51, I believe, if you don't want to actually read the entire thread. I just copied down posts that were relevant to my own experiments so it certainly leaves out a lot of information, but it's a start.


Yes, I downloaded your word sheet, is just that I'm a bit anxious to try the reaction:D

btw, what about aluminium reducing sodium?

MrHomeScientist - 20-5-2013 at 07:04

The issue with using this reaction to produce sodium is that the sodium alkoxide is much less soluble in the reaction solvent than the potassium counterpart, so it's much less (or possibly not at all) effective as a catalyst. The thought was that creating a longer chain tertiary alcohol would be necessary for Na, and there was a separate thread created in the Organics section devoted to it (this has been linked to in this thread a number of times). I don't think there was much progress on that front, unfortunately.

I was certainly anxious the first time too, especially since each failure represents 4 hours of lost time! It went surprisingly well for me in my trials, though, except for coalescence. I think I'm just not running at a high enough temperature. As long as you follow the procedures that have been proven to work by other members, you should hopefully be in the clear.


For your enjoyment, here's a short clip of me trying to dispose of the unrecoverable potassium fines. First in isopropanol, then a big bucket of water. http://www.youtube.com/watch?v=KF79gF81-Dw

It's a very angry reaction in both, but at least the water doesn't catch fire! Use a large bucket, and slow addition. If you only fill it halfway, any splatters from the crackling K are contained in the bucket.

Toluene - 20-5-2013 at 07:29

Thank you so much for the video is awesome how the isopropanol reach enough temperature to self ignite.

As for the sodium how much longer has to be the chain? 6 carbons?

MrHomeScientist - 20-5-2013 at 08:32

I think it's not that the IPA gets hot enough to self-ignite - rather, the sparks produced by the reacting K are capable of igniting the alcohol vapor floating nearby.

I was never involved in the research for sodium production, so I don't have much information about it. I'd recommend you take a look at the "synthesis of longer tertiary chain alcohols" thread in the Organics section (at least I think that's what it was called).

blogfast25 - 21-5-2013 at 09:08

Quote: Originally posted by Toluene  
Hello, I have a couple of questions: Did anybody try to use another alcohol as catalyst? I have already ordered my t-butanol ,but til it arrives I decided to take a look at household chemicals, I found an interesting alcohol:ethylenglycol (ethanodiol) I know it is not a three or more carbons alcohol so, my question is : should I give a try with the ethylenglycol or I'm just wasting my time?

Another question. I have read the whole thread and I saw that some people say that sodium might be reduced with aluminium did anybody try this?


We're 99 % certain that only t-alcohols work: primary and secondary alcohols get chewed up very quickly in these hot, alkaline conditions. The choice of using a tertiary alcohol must have been a very deliberate one on the part of the inventors and based largely on tertiary alcohol's resistance to oxidation in alkaline conditions. p- and s- alcohols oxidise fairly easily to corresponding aldehydes, ketones or acids.

Apart from t-butanol, 2-methyl butan-2-ol (aka 2M2B) also works perfectly, it's the one I use. Longer chain (C5, C6 and higher) t-alcohols of the general structure 2 methyl alkan-2-ol could work too but are less available and as yet largely untested.

Sodium hydroxide can be reduced with Al in very messy, thermite-like conditions but it's highly unlikely to work here. Still, be a trailblazer and be the first to try it!

Magnesium seems eager to form structures like R-Mg- and R-O-Mg- (see Grignard Reactions), of aluminium that is not so evident (at least not to me)...


[Edited on 21-5-2013 by blogfast25]

Toluene - 24-5-2013 at 11:30

Quote: Originally posted by blogfast25  
Quote: Originally posted by Toluene  
Hello, I have a couple of questions: Did anybody try to use another alcohol as catalyst? I have already ordered my t-butanol ,but til it arrives I decided to take a look at household chemicals, I found an interesting alcohol:ethylenglycol (ethanodiol) I know it is not a three or more carbons alcohol so, my question is : should I give a try with the ethylenglycol or I'm just wasting my time?

Another question. I have read the whole thread and I saw that some people say that sodium might be reduced with aluminium did anybody try this?


We're 99 % certain that only t-alcohols work: primary and secondary alcohols get chewed up very quickly in these hot, alkaline conditions. The choice of using a tertiary alcohol must have been a very deliberate one on the part of the inventors and based largely on tertiary alcohol's resistance to oxidation in alkaline conditions. p- and s- alcohols oxidise fairly easily to corresponding aldehydes, ketones or acids.

Apart from t-butanol, 2-methyl butan-2-ol (aka 2M2B) also works perfectly, it's the one I use. Longer chain (C5, C6 and higher) t-alcohols of the general structure 2 methyl alkan-2-ol could work too but are less available and as yet largely untested.

Sodium hydroxide can be reduced with Al in very messy, thermite-like conditions but it's highly unlikely to work here. Still, be a trailblazer and be the first to try it!

Magnesium seems eager to form structures like R-Mg- and R-O-Mg- (see Grignard Reactions), of aluminium that is not so evident (at least not to me)...


[Edited on 21-5-2013 by blogfast25]


Thank you very much, My t-butanol at last arrived!, so, the sodium then may be reduced by the magnesium in the conditions of this experiment?, just using NaOH instead of KOH?

[Edited on 24-5-2013 by Toluene]

[Edited on 24-5-2013 by Toluene]

blogfast25 - 25-5-2013 at 06:38

Quote: Originally posted by Toluene  
[
Thank you very much, My t-butanol at last arrived!, so, the sodium then may be reduced by the magnesium in the conditions of this experiment?, just using NaOH instead of KOH?



Sodium is much more problematic than potassium with this method. Consult the original patent (see top of this long thread) to get a good idea of that difficulty.

Some (like me) believe longer chain t-alcohols might work better for sodium but as yet that remains an unproved hypothesis.

[Edited on 25-5-2013 by blogfast25]

hyfalcon - 25-5-2013 at 14:12

I'm going to give this a shot. My t-butanol came in the other day. Will this be a good substitute for the Shellsol D70?

http://images.tikibrand.com/lamplight/llfwholesale/knowledge...

Boiling point seems to be about the right range.

blogfast25 - 26-5-2013 at 04:43

Yes, as perfect as can be.

I'm always glad to see someone else having a stab at this preparation, so good luck!

[Edited on 26-5-2013 by blogfast25]

Toluene - 27-5-2013 at 06:53

Hello,

Yesterday I tried to produce sodium metal from NaOH, aluminium and the T-BuOH, I grinded aluminium foil in a coffee grinder to make it finer, I followed all the instructions and I got nothing, the truth is that I didn't measure the reagents properly since my precision scale hasn't arrived yet, I'll keep trying on this method

plante1999 - 27-5-2013 at 08:21

It need magnesium, not aluminium.

Toluene - 27-5-2013 at 09:26

Quote:
Quote: Originally posted by plante1999  
It need magnesium, not aluminium.


Yes, that is what it seems, but, If you can reduce it with aluminium under thermite conditions, why not try in this ones?, By the way, the sodium hydroxide turned brownish after 3 hours of refluxing and adding the catalyst, but the aluminium is still pretty shiny :(

blogfast25 - 27-5-2013 at 11:42

Toluene:

As I wrote on 21/5:

"Magnesium seems eager to form structures like R-Mg- and R-O-Mg- (see Grignard Reactions), of aluminium that is not so evident (at least not to me)..."

You're comparing apples and oranges. The reaction with magnesium requires a specific catalyst, clearly specific TO Mg, not to Al.

[Edited on 27-5-2013 by blogfast25]

Toluene - 28-5-2013 at 08:02

Quote: Originally posted by blogfast25  
Toluene:

As I wrote on 21/5:

"Magnesium seems eager to form structures like R-Mg- and R-O-Mg- (see Grignard Reactions), of aluminium that is not so evident (at least not to me)..."

You're comparing apples and oranges. The reaction with magnesium requires a specific catalyst, clearly specific TO Mg, not to Al.

[Edited on 27-5-2013 by blogfast25]


Thank you, since my magnesium seems that doesn't want to arrive, I'm trying it with a metal sharpener (wich I think doesn't have a very pure magnesium content), results this night :cool:r

blogfast25 - 1-6-2013 at 06:42

I’ve been toying with the idea of recovering the catalyst in some way or other and have made a first step in that direction today. As I wrote above on this page:
Quote: Originally posted by blogfast25  

Another observation (which I’ve made several times) is the following. One objective of this test was to explore the possibility of catalyst recovery/recycling. I’ve noticed many times that the supernatant post-reaction solvent, when decanted off and allowed too cool settles to a viscous, even jelly like material. The proposed reaction mechanism predicts that all catalyst is present in the solvent as the relevant potassium alkoxide, thus the solvent should in principle be recoverable without further to do.

Alternatively, treatment with acid should hydrolyse the potassium alkoxide to salt and the alcohol in question (but the alcohol is soluble in the solvent, of course). Today I checked the supernatant liquid that I had set aside and a whitish, jelly like precipitate had separated out. Could this be potassium 2-methyl butan-2-oxide? I’ve yet to decide what to do with it but there’s enough for two small scale tests.


The supernatant with its white/greyish precipitate had been parafilmed and set aside for a few weeks and the consistency of the liquid had returned completely to that of the virgin solvent. The precipitate had collected at the bottom. This was filtered off and washed with a bit of xylene (the only solvent I had at hand that is miscible with kerosene and is quite volatile too), then it allowed to dry for a few days. It then looked like this (on a 110 mm filter paper):



There’s 4.17 g of it.

This was mixed with about 20 ml of water but it’s quite hydrophobic. Then slowly about 30 ml of 36 % HCl was added. It turned out that the darker matter was mostly unreacted magnesium, so the addition was done carefully and the solution heated up very considerably.

If the product contains potassium alkoxide then it should have been hydrolysed acc.:

KOR + HCl → KCl + ROH

Half way through the HCl addition I could already see an oily phase beginning to form on top. After the addition, most of the watery phase (presumed MgCl2 + KCl solution) was separated with a separation funnel, the rest of the mixture was decanted off into a normal size test tube. The organic phase (quite murky) can clearly be seen:



Although it smells of 2-methyl-2-butanol (t-amyl alcohol, the catalyst used) it can’t be excluded that traces of the original kerosene or xylene may be present in this organic phase. I happen to have a micro-still (max capacity 3 ml) and will now try and distil over the presumed 2M2B to get a crude BP.

Edit:

The micro-distillation’s results were a bit inconclusive: 0.5 ml (or thereabouts) is a bit little for a pre-distillation work up and just adding some CaCl2 didn’t really cut it. The result was bumpiness and no way to determine an accurate BP. I did get three drops of turbid distillate that reeked of 2-methyl-2-butanol. But it’s probably heavily contaminated with water and some of the excess HCl.

This is the micro-still:



Right: thermometer; Centre: silicone oil bath and boiler; Bottom: micro-burner (methanol); Top: still head; Left: fractionating tray.



[Edited on 1-6-2013 by blogfast25]

[Edited on 1-6-2013 by blogfast25]

blogfast25 - 2-6-2013 at 09:27

Today I performed an experiment using decalin as a solvent. Decalin, or decahydronaphtalene, has the advantage of a higher density compared to straight or branched alkanes of similar C numbers: 0.896 which is higher than that of molten potassium: 0.828 (at MP, Wiki). It’s also inert and has the right boiling point (trans: 187 C, cis: 196 C, mine is racemate I think).

Nurdrage had previously reported excellent results with tetralin which has an even higher density.

To demonstrate that K should float in decalin, a few small and fairly dirty K balls were suspended in decalin in a test tube, at 90 C. They float alright albeit not very convincingly (the dirt dropped off on melting):




So the usual set up with the usual ingredients (2M2B as catalyst) was tested, 50 ml decalin scale:



Using a sand bath the temperature rise was less steep and the initial hydrogen evolution (dehydration step) gentler than last time. Everything else also proceeded as normal:

• Checking for hydrogen (inverted test tube over refluxer top) tested positive each time
• Solvent clouded over as usual: formation of MgO

Except: no floating potassium!

I stopped the test slightly prematurely due to a technical problem and cooled down to below 70 C. After decanting off the supernatant liquid no potassium balls were observed but the grey/blue sludge did prove full of extremely fine potassium. No coalescence whatsoever though. Quite disappointing…



[Edited on 2-6-2013 by blogfast25]

MyNameIsUnnecessarilyLong - 13-6-2013 at 20:14

Had success with ~30g Mg chips freshly made on lathe, 60g KOH freshly crushed from flake, and 10.4mL t-butyl in approximately 300-350mL of Lamplight Ultra-Pure Paraffin Oil in a 500mL RBF. Most of the potassium ended up as fine particles with the few largest balls being about .5 - 1mm. I transferred it to another flask and plugged it into a rotary evaporator to see if spinning would help coalescence. It didn't, and actually looks like a lot of the K particulate might've oxidized in the process.

I'm going to try centrifuging a small portion in the next few days.

blogfast25 - 14-6-2013 at 03:40

Quote: Originally posted by MyNameIsUnnecessarilyLong  
Had success with ~30g Mg chips freshly made on lathe, 60g KOH freshly crushed from flake, and 10.4mL t-butyl in approximately 300-350mL of Lamplight Ultra-Pure Paraffin Oil in a 500mL RBF. Most of the potassium ended up as fine particles with the few largest balls being about .5 - 1mm. I transferred it to another flask and plugged it into a rotary evaporator to see if spinning would help coalescence. It didn't, and actually looks like a lot of the K particulate might've oxidized in the process.

I'm going to try centrifuging a small portion in the next few days.


Well, that's certainly an novel approach [centrifuging] in this here context.

How long was your run and what was the average temperature (estimate)?

Did you load all reactants at once or did you used the stepped procedure (patent)?



[Edited on 14-6-2013 by blogfast25]

MyNameIsUnnecessarilyLong - 14-6-2013 at 15:36

Quote: Originally posted by blogfast25  
Quote: Originally posted by MyNameIsUnnecessarilyLong  
Had success with ~30g Mg chips freshly made on lathe, 60g KOH freshly crushed from flake, and 10.4mL t-butyl in approximately 300-350mL of Lamplight Ultra-Pure Paraffin Oil in a 500mL RBF. Most of the potassium ended up as fine particles with the few largest balls being about .5 - 1mm. I transferred it to another flask and plugged it into a rotary evaporator to see if spinning would help coalescence. It didn't, and actually looks like a lot of the K particulate might've oxidized in the process.

I'm going to try centrifuging a small portion in the next few days.


Well, that's certainly an novel approach [centrifuging] in this here context.

How long was your run and what was the average temperature (estimate)?

Did you load all reactants at once or did you used the stepped procedure (patent)?




I ran it for about 1 & 1/2 - 2 hours one night but switched it off and restarted it the next day for an additional 2 & 1/2 hrs. After the initial run, the medium was whitish-grey and very viscous-almost jelly consistency and when cooled, a 3-4mm thick whitish layer formed at the surface. No potassium was seen at that point.

The 2nd run became a darkish grey color about 1hr in, and that's when little potassium balls started popping out.

I mixed everything together in one pot. I tried this synthesis at half-scale last year and dripped in the t-butyl once everything started refluxing, and I got absolutely nothing from that except brownish-grey sludge. I was also using mineral oil for that one instead of thin parrafin oil, and the magnesium was made by grinding a Mg firestarter into oil, and flaked KOH was added instead of crushed.


I broke all my high temp thermometers a few months ago, so I'm not certain how hot it was. It was at a very slow boil (roughly 5-10 bubbles per second), and just by touching the flask it didn't feel to me much hotter than a flask of boiling water. I'd guess it was around 250F.

I noticed that some t-butyl was dripping out of the top of the condenser at the same time the hydrogen was evolving. I sucked air through the condenser manually and that didn't seem to condense it fast enough. Next time I'm going to try coolant.


Pic of reactor during the first 10 minutes:
http://i.imgur.com/d1dxcK8.jpg

[Edited on 6-15-2013 by MyNameIsUnnecessarilyLong]

blogfast25 - 15-6-2013 at 04:49

Interesting how you obtain a jelly like solvent too. I get that every time the reaction is successful. I think it's the K-alkoxide exuding from the solvent.

250 F sounds really lo me.

MyNameIsUnnecessarilyLong - 15-6-2013 at 20:43

Has anyone tried re-using solvent from previous reactions?

Most of the particulates have settled out and it looks pretty clear now. This thin paraffin oil is relatively expensive and I'd like to not have to buy more for each rxn.
Quote: Originally posted by blogfast25  

250 F sounds really lo me.


Maybe. I just remembered I have an IR thermometer. Do you think taking a reading on the glass exterior above the mantle portion would give an accurate representation? Or would it be better to pull the flask out of the mantle for a sec and read the bottom?

blogfast25 - 16-6-2013 at 03:16

Quote: Originally posted by MyNameIsUnnecessarilyLong  
Has anyone tried re-using solvent from previous reactions?

Most of the particulates have settled out and it looks pretty clear now. This thin paraffin oil is relatively expensive and I'd like to not have to buy more for each rxn.




I don't think there should be a problem with that a all and have been meaning to try that. Remember that it may contain some dissolved K t-butoxide but that's not a problem either...

Sublimatus - 16-6-2013 at 08:07

Do we have any good guesses as to the composition of the white smoke seen in MyNameIsUnnecessarilyLong's photo above? I'd always assumed it was the t-butanol, but I'm running the reaction against just now, and the smoke appeared even though I hadn't added any alcohol yet.

It appeared when the reaction mixture reached ca. 90 C, slowly at first, and then became more dense along with violent bubbling of the solvent. Around 130 C the smoke was pushed out of the apparatus (presumably by hydrogen), and no more was generated.

Is this smoke the result of some reaction between the magnesium and hydroxide? The magnesium and the solvent? Is it simply an aerosol kicked up by the sudden escape of the hydrogen gas?

This run I'm using kerosene as the solvent. In the past I've used mineral oil and lamp oil (smelled of naptha). In all cases I've seen this smoke, accompanied by violent bubbling, which then subsides about as quickly as it began.

hyfalcon - 16-6-2013 at 10:42

I would guess it's the water being driven off by those temperatures.

Sublimatus - 16-6-2013 at 11:10

There's something I hadn't considered.

I suppose I could try condensing it next time. Thanks for the hypothesis. :)

Edit:

TLDR below.

Well, I've just finished my fourth shot at getting this reaction to work. All four runs have seemingly yielded no potassium.

All four runs were with 3.5 grams 99.96% very thin magnesium turnings broken up to very small pieces and roughed up in a mortar and pestle under oil, 7.0 grams ACS grade potassium hydroxide prills, and 1 mL of redistilled t-butanol.

During all four runs, beginning at ca. 90 C, a vigorous evolution of gas bubbles and dense white smoke was observed for a few minutes. Capturing some of the gas after the smoke had dissipated confirmed that hydrogen was present.

In the first three runs, the catalyst was added before heating. In the fourth run the catalyst was added at ca. 140 C, after the evolution of smoke had stopped.

The first and second attempts used mineral oil as the solvent, the kind you find at the pharmacy. Approximately 4 hours at 220 C gave no potassium. The resulting reaction mixture was composed of very black remnants of the magnesium turnings and an insoluble white material, possibly MgO or Mg(OH)2.

The third attempt used lamp oil as the solvent. The exact composition is unknown, but it smelled precisely like the mineral spirits one can buy as paint thinner, and had a maximum boiling point of ca. 160 C. 4 hours at that temperature gave the same result as the first two attempts.

The fourth attempt used kerosene as the solvent. The source was a blue quart bottle sold by Coleman as kerosene for their line of lamps. It smells very similar to automotive diesel. The maximum temperature achieved during the reaction was ca. 185 C, which was maintained for 4 hours before shutting down.

As before, the result was a few remaining black fragments of magnesium and an insoluble white material. No potassium spheres or fines were observed. Water was carefully added to a small portion of the solvent and sludge to see if any reaction would occur. No heat, fizzing, or fire occurred.

TLDR: I've tried three solvents, (mineral oil, naptha?, and kerosene) with the best quality reactants I can obtain, but no potassium has been isolated.

Is there anyone with insight or suggestions as to what might be wrong?

The temperature might be the culprit, but I can't see any way to exceed the temperatures I've reached. Cranking up the hot plate seems to have no effect once vigorous boiling has begun.

[Edited on 6/16/2013 by Sublimatus]

MyNameIsUnnecessarilyLong - 16-6-2013 at 13:28

When I went to transfer the mixture to another flask after it partially cooled, more white smoke would suddenly appear. I closed it up and let it cool down to about room temp, then opened it up and there was still a small amount of smoke coming out of the solution.

Could this be a reaction between the potassium and humidity?
Quote: Originally posted by Sublimatus  

Is there anyone with insight or suggestions as to what might be wrong?



Have you tried using powdered/crushed KOH?

[Edited on 6-16-2013 by MyNameIsUnnecessarilyLong]

Sublimatus - 16-6-2013 at 18:11

I did grind the KOH in the second run, but not the rest. I should've been more consistent. :P

I'll grind it up and give it another go in a day or so. I'll report back with success or to beg for more suggestions.

blogfast25 - 17-6-2013 at 04:56

Quote: Originally posted by Sublimatus  
I did grind the KOH in the second run, but not the rest. I should've been more consistent. :P

I'll grind it up and give it another go in a day or so. I'll report back with success or to beg for more suggestions.


In your case I would suggest to:

* try a reagent grade Mg powder or a clean pyro grade
* try to measure temperature at least once, just to be certain. Too low temperature slows down everything. You could even measure it in a 'dummy run', if you have no means of inserting a thermocouple during reaction.

My psychic octopus tells me you're close to success! :)

Sublimatus - 17-6-2013 at 05:47

It's 99.96% magnesium. I'd be surprised if that wasn't clean enough, but I'll look around to see if I can find better. Perhaps the 0.04% contamination is a serious poison for the reaction.

I've had a high-temperature thermometer (-10 to 260 C) right in the reaction solvent on every run. The temperatures I report are the approximate average I observed over the four hours, as there's a small amount of fluctuation.

If your psychic octopus is confident, I'll press on. :P

blogfast25 - 17-6-2013 at 05:55

Sublimatus:

My email notification is on the blink, so I had to 'quickread' your comment. Grrr...

220 C and 99.96 % Mg seem more than adequate. But for the latter a truly powdered form may be worth trying. Octopussy is nodding vigorously so it's all good... :)

Once the greatest experimenter on this board ('len1') didn't get any K either, so there are are some exceptional conditions that can cause failure. Truly bizarre.

hyfalcon - 17-6-2013 at 10:49

I just got my heat source set up in the shop. I've got 200-325 mesh mixed with some 2X4 mm chips of Mg and also some thin machine turnings. I'm going to try a run with a mix of all three. I'm going to pick up some white sand for a sand bath latter today. I'll probably make the run tomorrow.

[Edited on 17-6-2013 by hyfalcon]

blogfast25 - 17-6-2013 at 12:21

Quote: Originally posted by hyfalcon  
I'll probably make the run tomorrow.



Fingers painfully crossed! ;)

Pyrocystis Lunula - 18-6-2013 at 11:32

Greetings everyone! Longtime reader here who has decided to join in the quest for Potassium.
I have been trying this synthesis for the past few days and have been met with failure on the 5 runs I have attempted so far. Here is a quick rundown of what I have tried
Note: All trials use the same Mg, KOH, and t-butanol. Mg is a coarse powder that appears dark but still has plenty of shiny pieces in it. KOH is tech grade flakes from EBay. T-butanol is 99% from Ebay with freeze/melting point matching literature. All trials have used 125ml erlenmeyer flasks and an electric coil kitchen hotplate that I have previously recorded reaching approximately 220 C when dehydrating some baking soda as a test. I dropped my high temperature thermometer and haven't bought a replacement yet.

Trial 1: 3.1g Mg, 6.1g KOH, 1ml t-butanol all placed into flask with 50ml melted paraffin wax (only solvent I had available the first day). Hotplate was set to high and refluxer attached with PTFE tap being used to make an airtight seal. After approximately 5 minutes bubbling began and continued for the next hour. The solution gradually became cloudier and more opaque. After 4 hours, I turned off the heating and checked for any signs of potassium. No globules were identified and there was no reaction when water was poured over the mix after the wax was liquified with mineral spirits.

Trial 2: Same amounts as trial one but t-butanol was added after the bubbling had died down, mixed with 10ml of mineral spirits. A small amount of vapor escaped the refluxer but the majority of the liquid dripped back into the solution. Solution once again became opaque but no signs of potassium at the end of the 4 hours, failing water test once again.

Trial 3: 3.5g Mg, 6g KOH and 1.25ml t-butanol in 50ml of hypoallergenic baby oil. All added in beginning. Bubbling began as normal, solution once again became opaque, but after 4 hours of heating on high there were no balls of potassium. The contents had enlarged and turned a brownish color, very much resembling the sand mentioned before. Upon cooling, I noticed a gel-like layer coated the sediment underneath the baby oil. The oil was the same viscosity, but the gel was thick and opaque. Mixing with water produced no bubbling.

Trial 4: Suspecting that my magnesium was simply too oxidized to react and form the potassium, I tried activating it by mixing the powder in a weak hydrochloric acid solution. The powder was then filtered off and immediately pressed dry with filter paper until no moisture came off. 3.1g of this powder was then mixed with 6.1g KOH and 1ml of t-butanol in another 50ml of fresh baby oil. Bubbling appeared to be more viscous, but this could have simply been water I did not properly remove from the powder. In the end, the flask looked almost the same as the last trial with another layer of gel covering the sediment under the baby oil. Once again, no bubbling with water.

Trial 5: Currently in progress. 3g Mg were placed under 50ml of fresh baby oil which a tiny amount of iodine had been dissolved in. This was rapidly stirred and gently heated. The powder appeared to become brighter with small shiny flecks floating after stirring was stopped. When most of the purple iodine color cleared, 6g KOH and 0.75ml t-butanol were added, the refluxer once again attached, and heating started. Bubbling proceeded normally and as of 2 hours of heating the oil is still clear. The powders have gained volume and a slight crust is apparent on the top. Will report results later this evening. UPDATE: Now at 6 hours of heating, oil has become a cloudy pale yellow color. I've decided to just let it run for the rest of the night, hoping the extra time might give the reaction a better chance.

I believe my magnesium is the culprit here. I ordered a fresh ingot from galliumsource to file or drill turnings from that will not be heavily oxidized. Examining portions of the previous wax runs that did not have water, I noticed a thin layer of the gel-like coating on the reactants. Is this the K-butoxide?

[Edited on 18-6-2013 by Pyrocystis Lunula]

MyNameIsUnnecessarilyLong - 18-6-2013 at 15:02

Quote: Originally posted by Pyrocystis Lunula  


Have you tried breaking up the slag and stirring things occasionally?

My mix was cloudy after the first couple hours and couldn't see any K. I saw a small pile of shiny Mg and KOH in the bottom that was encased in a hard Mg-oxide aggregate, so I reached in with a metal skewer and carefully broke everything up and swirled the flask periodically every 15 minutes or so. The mix eventually became grey after about an hour of that

blogfast25 - 19-6-2013 at 03:37

Pyrocystis Lunula:

Thanks for joining our potassium 'fun/misery' and thanks also for that very concise first post (please keep reporting like that).

When no potassium is obtained at all, I'm inclined to blame the reducing agent, even though quite mysteriously we don't really know WTF might be wrong with it!

So by all means try a different and hopefully better grade of Mg.

Good luck.

MrHomeScientist - 19-6-2013 at 05:32

Quote: Originally posted by hyfalcon  
I would guess it's the water being driven off by those temperatures.


I don't believe that's correct. If you look back a few pages at one of my other posts, I put up a few pictures of the smoke from one of my runs. It seems to condense into a white solid as the smoke dissipates. This has me pretty convinced that it is t-butanol boiling off. My runs still produced K, so I apparently don't lose it all in the smoke plume.

Sublimatus - 19-6-2013 at 05:44

Quote: Originally posted by MrHomeScientist  
I don't believe that's correct. If you look back a few pages at one of my other posts, I put up a few pictures of the smoke from one of my runs. It seems to condense into a white solid as the smoke dissipates. This has me pretty convinced that it is t-butanol boiling off. My runs still produced K, so I apparently don't lose it all in the smoke plume.


I don't think that's right. In my last run I didn't add the t-butanol until after the white smoke had been generated and escaped from the apparatus between 90 and 130 C.

Next time I try this I'm going to include a cold trap to try to condense the smoke and see what it is.

MyNameIsUnnecessarilyLong - 19-6-2013 at 10:01

Quote: Originally posted by MrHomeScientist  
Quote: Originally posted by hyfalcon  
I would guess it's the water being driven off by those temperatures.


I don't believe that's correct. If you look back a few pages at one of my other posts, I put up a few pictures of the smoke from one of my runs. It seems to condense into a white solid as the smoke dissipates. This has me pretty convinced that it is t-butanol boiling off. My runs still produced K, so I apparently don't lose it all in the smoke plume.


My white smoke definitely smelt like t-butyl. Could be an azeotrope with whatever water gets liberated

hyfalcon - 19-6-2013 at 11:16

I've got less then an hour of reflux left. It isn't looking too good at the present. Air is definitely not enough cooling. I stacked two condensers and a fractionating column together to keep things under reflux. I don't know if we are starting out dry enough for this to work right or not. How hard is it to dry your KOH out somewhat before starting? I used 500ml of a water thin paraffin based lamp oil. MSDS says that it boils at 220 C. I added 61.9 g of KOH to a 1000ml 2-necked flask along with 10.5g of 200-325 mesh pyro grade Mg along with 10.5g of Mg chips and then 10.5g of Mg turnings. I had the normal H2 emission at the expected temperatures. If I did anything wrong in retrospect, I think I used too much t-butanol. I tried something different to to t-butanol. I added 3ml at the start and mixed another 7ml in some extra lamp fuel and added to a sep funnel that I had on the second neck. After I started hard reflux and start dripping the extra t-butanol in on a timed release. I'll report back when the reflux is done and things have cooled and I can check for fines.


---------

Well, on clean up, I had a couple flashes of light in the flask when I doused it in the 5 gallon bucket of water. I noticed a lot of unreacted Mg in the bottom of the flask. Somehow I don't think my swirling was enough to keep the reactants mixed properly.

[Edited on 19-6-2013 by hyfalcon]

elementcollector1 - 19-6-2013 at 11:17

Too little Mg, I think... I always thought the ratio was 6.1g KOH:3.1g Mg, or 61g and 31g in your case.

MrHomeScientist - 19-6-2013 at 11:43

Quote: Originally posted by Sublimatus  
I don't think that's right. In my last run I didn't add the t-butanol until after the white smoke had been generated and escaped from the apparatus between 90 and 130 C.

Next time I try this I'm going to include a cold trap to try to condense the smoke and see what it is.


Huh, that's really strange. I would have bet money on it being the alcohol. If you can collect some I'm very interested in what it is. Sounds like you used a number of different oils so it's probably not from any particular solvent, either. Weird...

Sublimatus - 19-6-2013 at 12:31

I also thought it was the alcohol, up until that last run where I forgot to add it before heating things up.

I'm preparing another run now. I've set up a trap at the end of the apparatus that I'm going to cool with a methanol/dry ice mixture to try to capture whatever that gas or aerosol is. It's most definitely overkill, using such a strong coolant, but I figured I'd just bring out the big guns right away, rather than screwing around.

__________________________________________________


Edit:

Disappointingly, the smoke was not generated violently enough to even make it to the trap. It filled the head space in the roundbottom quite densely, but after a minute or so disappeared (without passing up through the condenser).

It seems clear that at least part of the smoke isn't the alcohol. If it was water, I think it would simply reflux under the condenser without dissipating, though I suppose it could be consumed in some reaction in the flask.

I'll have to run this again later with the same conditions as my fifth experiment to get the violent generation of smoke. This time I ran the magnesium through a coffee grinder, and smashed the potassium hydroxide pellets under oil in a mortar in pestle. Why this made the smoke generation less violent, rather than more, I don't understand.

I'll report my failure or success in a few hours.


[Edited on 6/19/2013 by Sublimatus]

hyfalcon - 19-6-2013 at 14:01

I'm looking for a nickel crucible. I'm thinking about running a batch of KOH through a cycle of 800C for about 4-5hrs then see if that helps things along somewhat.

MyNameIsUnnecessarilyLong - 19-6-2013 at 16:45

Quote: Originally posted by hyfalcon  
I've got less then an hour of reflux left. It isn't looking too good at the present. Air is definitely not enough cooling. I stacked two condensers and a fractionating column together to keep things under reflux. I don't know if we are starting out dry enough for this to work right or not. How hard is it to dry your KOH out somewhat before starting? I used 500ml of a water thin paraffin based lamp oil. MSDS says that it boils at 220 C. I added 61.9 g of KOH to a 1000ml 2-necked flask along with 10.5g of 200-325 mesh pyro grade Mg along with 10.5g of Mg chips and then 10.5g of Mg turnings. I had the normal H2 emission at the expected temperatures. If I did anything wrong in retrospect, I think I used too much t-butanol. I tried something different to to t-butanol. I added 3ml at the start and mixed another 7ml in some extra lamp fuel and added to a sep funnel that I had on the second neck. After I started hard reflux and start dripping the extra t-butanol in on a timed release. I'll report back when the reflux is done and things have cooled and I can check for fines.



62g KOH/31g Mg (just chips), and water-thin paraffin oil is exactly what I used in my reaction. Except I used about .4mL more t-butyl than you did and added it all before heating.

The only difference seems to be the amount of stirring. I swirled my flask approximately every 15 minutes and broke up the hard oxide chunks with a skewer. Try doing that next time.


I also didn't dehydrate my KOH. Just crushed it from flake purchased from DudaDiesel off ebay.

[Edited on 6-20-2013 by MyNameIsUnnecessarilyLong]

hyfalcon - 19-6-2013 at 17:45

How do you break up the chunks of oxide and keep oxygen out of the system?

MyNameIsUnnecessarilyLong - 19-6-2013 at 18:00

Quote: Originally posted by hyfalcon  
How do you break up the chunks of oxide and keep oxygen out of the system?



I didn't. I just opened up a joint and had at it with the skewer. It took me less than a minute to get most of it broken up into 1CM chunks or so. After closing it up, I purged the system with more butane.

Sublimatus - 20-6-2013 at 10:16

As I understand it, that could be a very bad idea, depending on the solvent being used.

220 C is at or in excess of the autoignition temperature of kerosene, depending on the grade. The introduction of oxygen from outside the apparatus could start a spontaneous fire. It would probably be a spectacular disaster, given <strike>then</strike> that the solvent would burn, potentially followed by the finely ground magnesium.

The autoignition temperature for mineral spirits is a bit higher, and I imagine it should be even higher for mineral oil. In any case, be careful.

The reaction I started yesterday seems to have failed to produce potassium. One thing I've come to realize is that quite a bit of magnesium is left after stopping the reaction. I'm not sure if this is due to passivation (the magnesium is coated in something black), or insufficient temperature (the kerosene maxes out at 184 C reflux). I may go back to trying mineral oil, since 220+ C can be achieved, and I'm using different potassium hydroxide and magnesium than I used the one time I attempted this reaction with mineral oil.

[Edited on 6/20/2013 by Sublimatus]

hyfalcon - 20-6-2013 at 13:42

I've had some etching in my 1000ml 2 neck using this solvent. Make me think things where kind of "wet".

MyNameIsUnnecessarilyLong - 20-6-2013 at 15:42

Quote: Originally posted by Sublimatus  
As I understand it, that could be a very bad idea, depending on the solvent being used.

220 C is at or in excess of the autoignition temperature of kerosene, depending on the grade. The introduction of oxygen from outside the apparatus could start a spontaneous fire. It would probably be a spectacular disaster, given <strike>then</strike> that the solvent would burn, potentially followed by the finely ground magnesium.

The autoignition temperature for mineral spirits is a bit higher, and I imagine it should be even higher for mineral oil. In any case, be careful.



I did let it cool a bit to the point where it was no longer boiling before I opened it.


I'm running the same reaction again right now (62.7g KOH/33g Mg/10.4mL t-butyl) with the same solvent used in my last run. My IR thermometer gives an average reading of 252F when it's at full boil. White smoke became vigorous at a mere 130F, then it completely halted for about a minute and quickly picked up once again at 180F. This intermittent production of smoke continued at least 5 more times. Can anyone speculate why this would occur in periods instead of as one continuous production?

EDIT: The medium has turned quite cloudy and white gel is building up just above the meniscus. Temperature of the solution now reads 280-293F, while the glass portion above the liquid fluctuates between 215-245F

+2.5 hours later: solution now looking pretty clear with no apparent gel, and oxide is settled out on top of shiny magnesium. I carefully cracked the oxide with a skewer to expose the unreacted magnesium and am now swirling the flask every 15 minutes. Temp now averages at about 330F.


+2 hours after breaking the oxide ^ and swirling every 30 mins, solution has gradually progressed from light gray to dark gray, and a few .5mm - 1mm balls of potassium can be seen when the flask is swirled. Temp is still at 330F


So, looks like it's perfectly OK to reuse solvent from previous (completed) reactions. I noticed my condenser with RT coolant still wasn't able to condense whatever was distilling off early on. Next time I'll try either chilled coolant or a longer column.

17g of magnesium was prepared on a lathe last night over the span of about an hour, the other 15g was left over from about 4 days ago. Both times I just captured the chips into an empty container in open air as they were coming off; no oil was used to prevent oxidation. The 62g KOH was crushed in about 5 minutes then put into a small bottle and covered with cling wrap. I stored the Mg this way too, and both the KOH and Mg were allowed to sit overnight like this before being put into the reaction.

[Edited on 6-21-2013 by MyNameIsUnnecessarilyLong]

Sublimatus - 20-6-2013 at 16:07

Yes, that sounds fine. My apologies if what I wrote came across condescendingly.

I just wanted to mention the possibility. Now and in the future there may be readers who aren't familiar with flash and autoignition points. I think it would be better to read about it in a thread where it's relevant, rather than becoming aware of them the hard way.

MyNameIsUnnecessarilyLong - 21-6-2013 at 00:04

This is the size of the magnesium I used: http://i.imgur.com/ZaYEaGP.jpg

Reaction just after the white smoke ceased: http://i.imgur.com/Lp16lCQ.jpg

Reaction once it became cloudy and a gel precipitate appeared: http://i.imgur.com/D0tFV8U.jpg

Reaction after about 2 hours. Practically no swirling was really done up to this point. Unreacted magnesium lies in bottom of the flask and it's at this point that I punctured and broke up the hard formations with a skewer and began periodically swirling the flask every 25-30mins: http://i.imgur.com/nJx9tJB.jpg

Reaction apprx 2 hours after breaking the aggregate and periodic swirling. Potassium balls are buried in and obscured by dark sediment but a few were seen when the flask was tilted: http://i.imgur.com/SS55Edy.jpg

Finally, swirling was stopped for about an hour, dark grey suspension settled out, and the solvent became crystal clear: http://i.imgur.com/KSD8RNz.jpg

A few clips of the vapor stage:
(2nd eruption @ 3:10 mark) http://www.youtube.com/watch?v=gfEGPTO3tZU

http://www.youtube.com/watch?v=8zRoUqoxJxE

Clip of the rxn when solution became like jelly: http://www.youtube.com/watch?v=gZ-1USwUEwI

blogfast25 - 21-6-2013 at 03:58

What can I say, MNUL?

In my case, when reaction proceeds, the appearance of the reagent mix evolves like this:

1) KOH flakes start breaking down (presumed loss of water)
2) Solvent starts clouding over (presumed formation of fine MgO)
3) Bottom sludge starts darkening
4) All being well globules of K start slowly appearing from about 1 1/2 to 2 h

In most cases the MgO seems to re-agglomerate.

Have you checked for hydrogen emission?

Pyrocystis Lunula - 22-6-2013 at 13:51

Success!
Update on my last unsuccessful trial: despite trying to activate the magnesium with iodine and prolonged heating (6 hour minimum) on 2 separate days, the oxidized magnesium powder did not produce any signs of magnesium. But on to my success!

A 99.95% pure magnesium block was used as my base source. I spent a day trying to figure out how to break it down into powder and turnings. What I ended up doing was wiping it with an oiled paper towel to prevent any extra oxidation, then took a hack saw to a corner. Oiling the saw kept the dust that came off in one place and this was collected. I also tried using a steel chisel and hammer to break off small chunks and ended up with irregular mm sized pieces from that. Finally, I used a drill attachment on a dremel tool because my drill has decided to not work. The turnings felt flaky and were slightly duller than the other samples, but were used nonetheless. All of this only amounted to 0.8g of shiny, fresh magnesium so I went with a small scale approach.

The mixed sample of powder, coarse chunks, and turnings were put in a 25 ml flask and 1.6g KOH flakes from the same source as my previous runs were added. This was put under 25ml of the same hypoallergenic baby oil and 0.4ml of t-butanol was pipetted in. A leibig condenser was attached to the flask with a rubber stopper and air cooling was run through it. The hot plate was set on high and within a few minutes vigorous bubbling began, The bubbling was much more vigorous than when the oxidized powder was used. Over the next hours, the magnesium turnings sticking above the KOH and powder melt slowly darkened to black. The oil remained clear every time I checked in on it. I didn't look at the time when I started and checking now, easily 5 hours later if not longer, I see a shiny blob poking out from the sediment. It does not look like any magnesium or bubbles and doesn't break apart on swirling so I am confidently stating I was successful, despite sloppy attention to procedure.

So some notes on my efforts so far:
Paraffin wax, as noted further up the thread, is NOT worth using. It was an enormous pain as other members said it would be. Go to your local grocery or general store and get some baby oil, it works well.
Comparing the original magnesium powder used to the shiny, fresh sample made from the block it is very clear the old powder was heavily oxidized. Dark grey, oxidized magnesium is once again showing to prevent the reaction from producing potassium. Trying to activate the heavily oxidized magnesium with a tiny amount of iodine was unsuccessful.
Small scale was successful, no word on yield yet however. When the flask cools, I will try to get an estimate. "One-pot" approach also shown to work at this scale, not sure if relevant.

It sure is satisfying to see that shiny blob resting in the flask after so many failed attempts. Don't give up those who haven't yet had success! Once I figure out a better way to process my magnesium block to usable quantities, I'll be scaling this reaction slowly upwards.

MyNameIsUnnecessarilyLong - 22-6-2013 at 16:10

Quote: Originally posted by Pyrocystis Lunula  
.



What diameter was the ball?

hyfalcon - 22-6-2013 at 16:55

I'm about to try ball milling my Mg under some lamp oil. It will make a holy mess, but I should be able to have maximum activation without worrying out oxidation on the Mg. Just to be on the safe side I'm going to do this remotely and outside.

blogfast25 - 23-6-2013 at 04:44

'Well done' to Pyrocystis Lunula. Good idea to downscale!

Re. Mg, I must really try my much finer and positively glistening Mg and compare it to my coarser and fairly dull looking reagent grade Mg. I'm still not convinced Mg is the only source of failure (in those cases where experimenters are seemingly doing everything right).

BobD1001 - 24-6-2013 at 17:59

Well I'm currently on my fifth attempt at this synthesis. All my attempts so far have been faliures to produce elemental K.

Attempts one and two utilized the following reagents:
-Lamplight Medallion lamp oil (about water thin) from Walmart
-Attempts 4 and 5 utilized Ultra Pure Clear Paraffin Oil
-Duda Diesel Potassium Hydroxide
-T-Butyl alcohol from an eBay seller (stated 99.7% purity)
-Fresh magnesium metal turnings from a 15lb AM50A alloy ingot. Approximately 93-95% percent purity with the majority of the remainder being Aluminum.

Here is a visual of my setup that I am using:


It consists of a 50ml boiling flask connected to a vigreux column wrapped in paper towels dampened with water/ipa to provide evaporative cooling. No solvent or t-butyl alcohol seems to escape the vigreux column. There is the a balloon affixed atop the column with small holes poked in it to prevent air from entering the apparatus as well as adding the t-butyl. Also a test tube is used to catch any hydrogen evolved from the reaction.

My reagents are added as follows: 5g KOH, 2g Mg, 30ml solvent, and .8ml t-Butyl.

I have run into the hydrogen production that everyone seems to mention, as well as this strange phenomenon where my solvent begins to 'harden' above the meniscus of the solvent in my reaction vessel (a 50ml boiling flask)



Attempts 4 and 5 utilized a new solvent, the Ultra Pure Clear paraffin oil which is said to be excellent for this reaction.

Currently my 5th attempt at this synthesis has been running for 5 hours at the time of writing this, with no signs of potassium production. Each run my magnesium turnings seem to darken significantly, to the point of being black, but are never reduced to this sand everyone mentions. My other attempts were terminated after 4 hours, however this 5th run will go for 8 hours to see if my time scale is too brief. My other runs also all utilized the one-pot method, whereas this time i have been incrementally adding the t-butyl.

I wonder if this could be impurities in the magnesium (notably the ~4-5% aluminum in this alloy) that could be passivating the turnings. Does anyone have input as to purity of the Mg used?

Here is a picture from the beginning of the current (5th) experiment:



Also of note, I am using my homebuild PID controlled hotplate, which turned out to be a great success, but I am keeping the temp of the plate at approx 260*C on this current run. The sand bath may be slightly cooler than the plate itself, however, previous runs were done at higher temps, however it caused my solvent to gel after a while. Attempt 3 even reached 350*C hotplate temp for an hour, but no change in reaction occurred aside from gelling of the solvent.

Does anyone have some input as to my potential issue here? I am thinking purity of Mg, but could it be the t-Butyl from eBay? (the melting.freezing point matches literature and the smell matches the camphor like odor that is cited online)

I would like to attempt this with t-Amyl alcohol if anyone would be generous enough to share a small amount of which I can reimburse you for as I cannot find it in reasonable prices for small quantities online. Or potentially a more pure source of Mg, which I'll purchase right away if the forum recommends.

[Edited on 25-6-2013 by BobD1001]

12AX7 - 24-6-2013 at 19:19

Hmm, aluminum is a good point: that alloy even burns slowly, in my experience, tending to make clumpy brain-like mounds of metal, oxide and nitride rather than simply burning with the familiar intense white flame. It still works fine for thermite reactions, but so does aluminum.

Any guesses what could be added to destabilize the aluminum (metal, oxide or hydroxide) and potentially prove the culprit and fix the reaction at the same time?

Tim

MyNameIsUnnecessarilyLong - 24-6-2013 at 20:05

Quote: Originally posted by BobD1001  


I'm using the same KOH and T-butyl vender (DudaDiesel/billythec) and Lamplight solvent as you, so it must be your magnesium or the particle size. My rxn runs at about 170°C but your higher temps shouldn't matter. Maybe purge the air out with propane/butane before heating? Did you stir things up after the gel formed?

With large magnesium turnings, you might need to add more to compensate for the lower surface area

[Edited on 6-25-2013 by MyNameIsUnnecessarilyLong]

BobD1001 - 24-6-2013 at 22:34

MNIUL,

I have tried agitating the reaction vessel by both swirling, and stirring with a glass stir rod to break up KOH/Mg clumps. My t-Butyl is from a different seller on eBay, selling it for use as a fragrance carrier, but I believe it is truly t-Butyl due to its matching of cited freezing/melting temps and smell. I just ordered an ingot of 99.9% pure mg from gallium source, so as soon as it arrives, hopefully there will be some potassium made!

MyNameIsUnnecessarilyLong - 25-6-2013 at 00:02

Quote: Originally posted by BobD1001  
MNIUL,

I have tried agitating the reaction vessel by both swirling, and stirring with a glass stir rod to break up KOH/Mg clumps. My t-Butyl is from a different seller on eBay, selling it for use as a fragrance carrier, but I believe it is truly t-Butyl due to its matching of cited freezing/melting temps and smell. I just ordered an ingot of 99.9% pure mg from gallium source, so as soon as it arrives, hopefully there will be some potassium made!




T-butyl from islandscentsability? I bought from him too, and his stuff is actually what I used in my first run, which was successful. And I used billythec's in my second run which was also fine.


Can you post a picture with scale of the size of magnesium turnings you're using?

BobD1001 - 25-6-2013 at 12:00

MNIUL,

Here's a picture of my magnesium turnings alongside a zinc brass penny. The turnings are only perhaps a thousandth of an inch thick, and easily turn to powdery fragments between my fingers. There is also quite a bit of fines along with the turnings, which are of a very fine particle size.



Hopefully the pure Mg i just ordered will do the trick. And have you noticed this reaction taking its toll in your reaction flask? My has been etched pretty badly, but it still very serviceable.

MyNameIsUnnecessarilyLong - 25-6-2013 at 13:25

Quote: Originally posted by BobD1001  



If your chips aren't being reduced to sand, perhaps it's because they're too large. The first failed rxn of mine was with drill turnings from a mg firestarter block that looked something like that. At the time I just figured it was the quality that was the problem. I'm tempted to retry firestarter Mg with a finer grade


This reaction will make your flasks ugly but it probably won't render them unsafe to use for heating purposes. My RBF got heavily pitted the first time doing this because I poured the KOH in first and neglected to stir things, so the KOH pieces sat in the same place for hours. Now, I put magnesium down first in the flask then lay the KOH on top. Once the water is liberated from the rxn the KOH will no longer etch things as much and you can stir it and let it rest wherever.

BobD1001 - 2-7-2013 at 22:41

Can anyone direct me to a source for t-Amyl alcohol, I'm spinning my wheels trying to find this stuff in a small quantity ~50ml or so.

If not, would anyone be willing to provide a small quantity to me? I would compensate you for your costs and shipping.

blogfast25 - 3-7-2013 at 09:10

Quote: Originally posted by BobD1001  
Can anyone direct me to a source for t-Amyl alcohol, I'm spinning my wheels trying to find this stuff in a small quantity ~50ml or so.

If not, would anyone be willing to provide a small quantity to me? I would compensate you for your costs and shipping.


Where are you?
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