Sciencemadness Discussion Board » Fundamentals » Chemistry in General » Make Potassium (from versuchschemie.de) Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues   » Detritus   » Test Forum

Pages:  1  ..  4    6    8  ..  66
Author: Subject: Make Potassium (from versuchschemie.de)
Sedit
International Hazard

Posts: 1935
Registered: 23-11-2008
Member Is Offline

Mood: Manic Expressive

 Quote: Originally posted by blogfast25 I’ve been thinking a bit about the problem of metal coalescence in the case of a typical set up (conical or round flask as reactor) because pok mentioned a test where the metal didn’t seem to want to coalesce into larger globules. A load of small globules store potential energy which is wholly or partly released when the globules coalesce into larger ones. This is reflected in the thermodynamical definition of surface tension s = dW/dS (J/m2) with W energy and S surface area. To increase the surface area (make smaller, not larger globules), dW = s x dS (with dS < 0). To promote the formation of larger globules you’d have to do something that actually increases surface tension, so the opposite of adding a surfactant. What could achieve that?

My only thought is in order to increase surface tension what is needed is a drop in temperature. Perhaps the larger globs are made by swirling the mixture while it is relatively cold as compared to heavy stirring when its very hot.

BTW can anyone think of a source of Mg I might have around the house? It doesn't have to be pure at all.

Knowledge is useless to useless people...

"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
ScienceSquirrel
Super Moderator

Posts: 1863
Registered: 18-6-2008
Location: Brittany
Member Is Offline

Mood: Dogs are pets but cats are little furry humans with four feet and self determination!

I am not rubbishing the claimed procedure but trying to take a reasonable position as a constructive critic.
It is possible that it may work under the right conditions but they could be quite critical eg D70 as the solvent, t-butanol as the co solvent / reactant and the right grades of potassium hydroxide and magnesium.
I would be delighted to see it work.
a_bab
National Hazard

Posts: 449
Registered: 15-9-2002
Member Is Offline

Mood: Angry !!!!!111111...2?!

 Quote: Originally posted by Sedit BTW can anyone think of a source of Mg I might have around the house? It doesn't have to be pure at all.

Jor
International Hazard

Posts: 950
Registered: 21-11-2007
Member Is Offline

Mood: No Mood

Is this magnesium fine for a Grignard, or is too fine (and thus too reactive):
http://cgi.ebay.de/100g-Magnesium-Pulver-200-m-Mg-/330501433...

If it fine, can an even finer powder be used for Grignards, as fine powder is more useful for producing some funny compounds such as magnesium silicide.

[Edited on 7-12-2010 by Jor]
Sedit
International Hazard

Posts: 1935
Registered: 23-11-2008
Member Is Offline

Mood: Manic Expressive

 Quote: Originally posted by ScienceSquirrel I am not rubbishing the claimed procedure but trying to take a reasonable position as a constructive critic. It is possible that it may work under the right conditions but they could be quite critical eg D70 as the solvent, t-butanol as the co solvent / reactant and the right grades of potassium hydroxide and magnesium. I would be delighted to see it work.

I have seen various attempts such as lens fail. He used the best and weighed things to a T yet he failed. As have others.

Im speculating that this has nothing at all to do with the proper equipment or process but am more inclined to believe that this is the result of contamination of some sorts such as perhaps Al in the Mg and the possibiliy that the formed Potassium aluminate is what is being reduced with Magnesium to yeild Potassium. Or there is the possibility that there is some sort of chlorocarbon in the solvent forming some sort of grignard which is acting like a catalyst in the reaction.

I know its far fetched but it seems the simpler someone goes with this the better results we see. Now we are sure that K can be generated by the reduction of KOH with Mg but the solvent and low temperature conditions seem to prohibit it. My logic is I say we start to test as many things as we can in hopes of activating the Mg the best way possible as well as trying various alloys. I personally want to try amalgumated Mg in KOH and see what I get out of it.

Thanks, I forgot all about pencil sharpeners. I know them and fireblocks are all I could think of.

Knowledge is useless to useless people...

"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
Sedit
International Hazard

Posts: 1935
Registered: 23-11-2008
Member Is Offline

Mood: Manic Expressive

Ok I have read and read and watched and read some more but.... Something really really bugs me here Pok that I hope you can answer quickly so I don't think you had time to think up a lie.

Where is your Mg in this picture

It appears there is alot of K around and what also appears as a bunch of unreacted KOH yet there is a single problem. There is NO PRECIPITATE. There should be Magnesium hydroxide or something of the sorts in there and there is NON.

I want to believe and I want to prove you right but..... Its starting to appear that the Mg we see in the start is nothing more then K that has been heated... stirred... then allowed to cool while still stirring. Then as we heat the solvent the "Mg" reacts with the KOH producing K. In reality it appears the KOH is doing nothing and there is no Mg there at all.

Im not trying to make an enemy here im only stating what I see and I honestly have a good sence of when someones pulling the wool over my eyes..... What would the motivation for such an act be?

You know what it takes to be a chemist since we are all overly critical so you MUST reproduce this experiment in order for it to stand again peer review. And before doing so you must allow us to tell you how to do it. If you can not do that then.... its not worthy of my money and time im willing to invest to prove your cause.

Knowledge is useless to useless people...

"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
woelen

Posts: 6839
Registered: 20-8-2005
Location: Netherlands
Member Is Offline

Mood: interested

Next weekend I plan to do a few different tests. I have no ShellSol D70, but I do have high grade paraffin oil (colorless viscous liquid, perfectly odorless and completely free of acidic and unsaturated ingredients). I also have the following chemicals:
- KOH, general reagent grade, 85...90% KOH, balance is water
- Al needles, ultra pure 99.99%
- Al powder, different grades, mostly pyro-stuff
- Magnalium powder (50Mg/50Al), pyrotechnic grade
- tert-butanol, synthetic grade (I need to melt this first, now it is a hard lump of ice, MP is 25 C)
- mercury

I could try different things systematically each time at 5 ml volumes of oil (one tenth of what Pok did):

- original experiment, using KOH, Mg turnings, paraffin oil and a drop of tert-butanol
- variation 1: Use Mg powder instead of Mg turnings
- variation 2: Use magnalium powder instead of Mg (influence of presence of Al)
- variation 3: Use magnalium powder with a tiny amount of Hg added for amalgation and destruction of oxide layer
- variation 4: Use Al needles instead of Mg
- variation 5: Use Al needles with a tiny amount of Hg added for amalgation

All experiments I can do in a test tube with a tight seal and a small thin tube as gas outlet for the hydrogen. Heating to 200 C is no problem with this. The use of mercury is a last resort for me due to the toxicity of the resulting waste and I will only use tiny amounts. I only do these if all other experiments fail.

If you have any ideas of how to improve the experiment series, please let me know. I want to try this next weekend. I really want this to be resolved. Making K-metal in this way sounds too good to be true, but I'll give it a try anyway.

The art of wondering makes life worth living...
Want to wonder? Look at https://woelen.homescience.net
Arthur Dent
International Hazard

Posts: 540
Registered: 22-10-2010
Member Is Offline

Mood: entropic

As soon as I have a minute of my time this Friday, i'll visit a few art supply stores in my neighborhood, maybe I'll get lucky and find that Shellsol solvent. I vaguely remember that name from a few years back as an oil paint solvent and brush cleaner. Maybe I'm wrong but it would be great to find that stuff (or something similar to it).

I just found out that "Bestine" rubber cement solvent is 100% pure heptane! Cool!

I found a good source of Tert-Butanol at $36 for 500 ml... Is that a fair price? Robert Pok potassium Prometheus Posts: 156 Registered: 5-12-2010 Member Is Offline Mood: No Mood  Quote: Originally posted by Sedit Ok I have read and read and watched and read some more but.... Something really really bugs me here Pok that I hope you can answer quickly so I don't think you had time to think up a lie. I'm not 24/7. But if you wish answers within seconds/minutes, I could tell you a date and time so we can do something like chatting. And I couldn't think about lies.  Quote: Originally posted by Sedit Where is your Mg in this picture http://www.versuchschemie.de/upload/files3/2272042_4948.jpg It's gone (this is a picture of the end of the reaction!).  Quote: Originally posted by Sedit It appears there is alot of K around and what also appears as a bunch of unreacted KOH yet there is a single problem. There is NO PRECIPITATE. There should be Magnesium hydroxide or something of the sorts in there and there is NON. There isn't alot of K around. The only K you can see are more or less large balls (shiny). The rest (gray stuff) is the Mg(OH)2 or MgO (the patent says "MgO" if I remember correctly). The reason why there isn't a precipitate or dust of Mg(OH)2 or oxide is: I put in the non-modified KOH-Chips at the beginning. And I did it without stirring continiously. Stirring would definitely devide the Mg(OH)2 or oxide into dust/powder.  Quote: Originally posted by Sedit I want to believe and I want to prove you right but..... Its starting to appear that the Mg we see in the start is nothing more then K that has been heated... stirred... then allowed to cool while still stirring. Then as we heat the solvent the "Mg" reacts with the KOH producing K. In reality it appears the KOH is doing nothing and there is no Mg there at all. I can absolutely understand that you are sceptically. I for myself would react exactly the same way. The Mg at the one photo (Mg in Shellsol + KOH in bag) really is Mg. (BTW: which photo do you mean? On versuchschemie.de I put a collage of photos where the second one shows the beginng of the reaction (after the total t-butanol addition). The shiny pearls ARE already K! The white stuff is KOH, the dark gray stuff is Mg (in reality more shiny). At the 4th photo you can see larger K balls coated by Mg filings. The grayish stuff here is KOH and MgO, the dark gray stuff is a mix of tiny K balls and Mg) If you would put some bought K into the Shellsol and devide it into such fine drops, it would rapidly oxidise on its surface (especcially if you assume, that I heated something like small K balls which united to form larger K balls). I HAD the problem sometimes, that K balls didn't unite.  Quote: Originally posted by Sedit Im not trying to make an enemy here im only stating what I see and I honestly have a good sence of when someones pulling the wool over my eyes..... What would the motivation for such an act be? The motivation for a lie would be recognition. Of course, I want this . Nevertheless it's a true experiment which I've done.  Quote: Originally posted by Sedit You know what it takes to be a chemist since we are all overly critical so you MUST reproduce this experiment in order for it to stand again peer review. And before doing so you must allow us to tell you how to do it. If you can not do that then.... its not worthy of my money and time im willing to invest to prove your cause. I know science. I know that reproduction is neccessary. But if I just do it again and again, this wouldn't help you. Some of YOU has to do it (scientifically - which means: in exactly the same way I did it.) Tell you how to do it? I thought you already have every detail. Look at versuchschemie.de and here. I made it like the patent with modifications that I already told you. You should easily be able to repeat this synthesis. I hope you know what "exactly" means: 50ml, 25cm-glaspipe with wet toilet paper (moisten it sometimes to prevent dehydration), balloon at the top with tiny hole, zero oxygen input, Mg filings made from 99-100% Mg made by filing with a medium file. and so on It might be that I really forgot one or two details. If this is the case, I would apologize - just ask! (I'll be back in 24 hours) I can also give you a really detailed description where no questions will be left. But this takes time and only be possible tomorrow or in max. 3 days. [Edited on 7-12-2010 by Pok] [Edited on 7-12-2010 by Pok] metalresearcher International Hazard Posts: 501 Registered: 7-9-2010 Member Is Offline Mood: Reactive  Quote: Originally posted by woelen but I do have high grade paraffin oil (colorless viscous liquid, perfectly odorless and completely free of acidic and unsaturated ingredients). Where can I get this oil ? Or can I melt candles which is also paraffin ? [Edited on 2010-12-7 by metalresearcher] wallschem Harmless Posts: 6 Registered: 17-11-2010 Member Is Offline Mood: No Mood I found this in an old Spanish chemistry book that is very similar to what pok is doing to synthesized Potassium. Instead of using Shellsol D70 and Ter-butol in this book they use Paraffin and Toluene at 180 degree Celsius. ScienceSquirrel Super Moderator Posts: 1863 Registered: 18-6-2008 Location: Brittany Member Is Offline Mood: Dogs are pets but cats are little furry humans with four feet and self determination! It depends where you live but some UK pharmacists sell very high grade liquid paraffin. It is about the viscosity of motor oil and completely odourless and tasteless as well. It used to be taken internally for constipation in humans but I think this use is now deprecated but it is still given to horses to get them 'moving', it is still used for eczema. Cheap as chips on eBay! http://cgi.ebay.co.uk/Liquid-Paraffin-500-ml-/260694362661?p... watson.fawkes International Hazard Posts: 2793 Registered: 16-8-2008 Member Is Offline Mood: No Mood  Quote: Originally posted by woelen - original experiment, using KOH, Mg turnings, paraffin oil and a drop of tert-butanol - variation 1: Use Mg powder instead of Mg turnings - variation 2: Use magnalium powder instead of Mg (influence of presence of Al) - variation 3: Use magnalium powder with a tiny amount of Hg added for amalgation and destruction of oxide layer - variation 4: Use Al needles instead of Mg - variation 5: Use Al needles with a tiny amount of Hg added for amalgation [...] If you have any ideas of how to improve the experiment series, please let me know. If you're going to try with Hg, do also try a variation with the different forms of Mg itself as opposed to the magnalium alloy. I'm not sure it's worth doing the experiments with the Al needles unless the ones with Mg or magnalium work. Aluminum isn't claimed in the patent; it's only mentioned there as a reducing agent in thermochemical processes. Using magnalium is interesting because it might give some indication if Al could either hinder or promote the reaction. Consider doing a mixed x% Mg + (100-x)% magnalium series. I'm not going to go so far as to suggest that you make alloy compositions in these percentages, but I'll mention it. I find it plausible that certain alloying agents might causing lattice strains that change the activation energy of Mg atoms leaving the lattice. That is, the thermodynamics might well be different for Mg alloys than pure Mg. Here's Wikipedia on magnesium alloys. The patent is silent on the purity and detail composition of the Mg used, but I have to imagine that they might have been using some "technical grade" alloy, say with as much as 3% non-Mg. That would be plenty of material to cause lattice strain and change activation energy. Related to this, the patent does state that the Mg is employed "particularly in the form of turnings", which I read as meaning that was the form they tried that worked best. Machining processes put really large stresses on crystal lattices, and there's mechanical strain remaining in the chips, as a rule. This mechanical strain is an available energy source to drive the reaction. In other words, the energy content in strained Mg is higher than that in non-strained (annealed, as it were). I note that Pok's Mg was in filings, which would have the same kind of strain resulting from a machining process. In short, it's possible that strained Mg and non-strained Mg should be treated as different reagents in this process. blogfast25 Thought-provoking Teacher Posts: 10334 Registered: 3-2-2008 Location: Old Blighty Member Is Offline Mood: No Mood Quote: Originally posted by a_bab  Quote: Originally posted by Sedit BTW can anyone think of a source of Mg I might have around the house? It doesn't have to be pure at all. Pencil sharpeners? Why make pencil sharpeners from Mg when the cheaper and safer Al will do? Sources of Mg include anodic protection blocks, often found on boilers and such like for corrosion protection, and flint blocks for emergency fire making (hikers, mountaineers, explorers – any multi purpose sports store will sell them). And the streets of eBay are paved with sellers of pyrotechnical Mg powder. Look for fairly pure, fairly coarse stuff…  Quote: Originally posted by Sedit Where is your Mg in this picture http://www.versuchschemie.de/upload/files3/2272042_4948.jpg It appears there is alot of K around and what also appears as a bunch of unreacted KOH yet there is a single problem. There is NO PRECIPITATE. There should be Magnesium hydroxide or something of the sorts in there and there is NON. I want to believe and I want to prove you right but..... Its starting to appear that the Mg we see in the start is nothing more then K that has been heated... stirred... then allowed to cool while still stirring. Then as we heat the solvent the "Mg" reacts with the KOH producing K. In reality it appears the KOH is doing nothing and there is no Mg there at all. Im not trying to make an enemy here im only stating what I see and I honestly have a good sence of when someones pulling the wool over my eyes..... What would the motivation for such an act be? There is precipitate (or 'stuff' as part of the deception), look closer. The Mg ‘at the start’ really looks like Mg filings, not like suspended K at all. If it is a hoax (I’m 50/50 on that), an emulsion of liquid K and some grit would have been created separately, then allowed to coalesce into larger globules. As regards ‘motive’, that is entirely beside the point: if it is a hoax we’ll probably never know the motive, nor does it matter.  Quote: Originally posted by Arthur Dent As soon as I have a minute of my time this Friday, i'll visit a few art supply stores in my neighborhood, maybe I'll get lucky and find that Shellsol solvent. I vaguely remember that name from a few years back as an oil paint solvent and brush cleaner. Maybe I'm wrong but it would be great to find that stuff (or something similar to it). I just found out that "Bestine" rubber cement solvent is 100% pure heptane! Cool! I found a good source of Tert-Butanol at$36 for 500 ml... Is that a fair price? Robert

Cool for the heptane, unfortunately it is totally UNSUITABLE for this purpose: way too low boiling point…

t-butanol, \$36 for 500 ml? Very, very good, go for it and sell some back to those here who can’t get any!!!

@woelen:

Finally a systematic approach (leading by example, eh? ) I’ve got stuff in the post but I’m holding fire until someone gets some results either way. I’m a little too agnostic to start experimenting just yet.

@pok:

Thank you for continuing to follow this thread. Nothing else is really required of you: it is now up to US to corroborate (or not) your results and conclude they are genuine or not. Thanks again!

[Edited on 7-12-2010 by blogfast25]
blogfast25
Thought-provoking Teacher

Posts: 10334
Registered: 3-2-2008
Location: Old Blighty
Member Is Offline

Mood: No Mood

 Quote: Originally posted by watson.fawkes Related to this, the patent does state that the Mg is employed "particularly in the form of turnings", which I read as meaning that was the form they tried that worked best. Machining processes put really large stresses on crystal lattices, and there's mechanical strain remaining in the chips, as a rule. This mechanical strain is an available energy source to drive the reaction. In other words, the energy content in strained Mg is higher than that in non-strained (annealed, as it were). I note that Pok's Mg was in filings, which would have the same kind of strain resulting from a machining process. In short, it's possible that strained Mg and non-strained Mg should be treated as different reagents in this process.

Isn’t nearly all size reduced Mg, with the exception perhaps of Rieke metal, formed by stressing the metal? Turnings are achieved by means of various kinds of stresses, filings (as used by pok) mainly shearing forces. Where would you get non-strained but size-reduced Mg? (Apart from Rieke metals). Event ‘atomised’ Al (spherical Al – not sure whether they do this in Mg too) will contain stresses on rapid cooling of the spray…
blogfast25
Thought-provoking Teacher

Posts: 10334
Registered: 3-2-2008
Location: Old Blighty
Member Is Offline

Mood: No Mood

 Quote: Originally posted by wallschem I found this in an old Spanish chemistry book that is very similar to what pok is doing to synthesized Potassium. Instead of using Shellsol D70 and Ter-butol in this book they use Paraffin and Toluene at 180 degree Celsius.

Interesting but really this is something we kind of accept: that it is possible to disperse molten K into a hot inert liquid. That would not be a 'solution' though, it is an 'emulsion'. You could even call it a 'potassium latex'. It should segregate quickly though, like oil and water mixtures (think salad dressing of liquid K and high boiling inert solvent! :cool

[Edited on 7-12-2010 by blogfast25]
blogfast25
Thought-provoking Teacher

Posts: 10334
Registered: 3-2-2008
Location: Old Blighty
Member Is Offline

Mood: No Mood

And as I keep saying till I’m blue in the face, for those who can’t get the Shellsol, a good quality kerosene should come very close. The Shellsol is really nothing more than a high grade paint thinner, I refuse to believe it contains some magical ingredient. But it may have the ideal ration of high BP and low viscosity...
ScienceSquirrel
Super Moderator

Posts: 1863
Registered: 18-6-2008
Location: Brittany
Member Is Offline

Mood: Dogs are pets but cats are little furry humans with four feet and self determination!

That is a recipe for potassium sand, sodium sand is made in a similar way.
The solvent is heated up with the metal in it then vigorously shaken or stirred while cooling so the metal remains in very fine particles.
The high boiling solvent is then removed under dry argon and replaced with hexane or similar.
It is a very reactive reducing and metallating reagent.
watson.fawkes
International Hazard

Posts: 2793
Registered: 16-8-2008
Member Is Offline

Mood: No Mood

I went over the patent last night, to see if I'd notice new things not mentioned yet in this thread. I noted a number of things.
• The abstract mentions an alcohol as a "reaction accelerator". I'm guessing the authors managed to make this work without it, albeit in some commercially impractical way.
• The authors mention doing the reaction under increased pressure. I know one member here with an autoclave (hint, hint). From a physical chemistry point of view, if this is relevant, it means that this reaction is limited by activation energy, because that's what higher pressure gives you&mdash;extra activation energy.
• The patent states that Mg(OH)2 is formed dehydrating KOH, and that MgO is formed at higher temperatures. Example 1, however, categorically states that the residue was MgO. Is conversion really total? It matters because Mg(OH)2 sequesters more oxygen per mole Mg than does MgO.
• Example 1 says that potassium t-butylate is left as a residue, which they extract as a solute from 1,4-dioxane. They don't actually state that this is where the rest of the 13% K ends up, and they don't mention if this reside contains any KOH.
• The residue question is even more interesting in Example 6, where they mention the residue contains Mg butylate. This seems like a bona-fide side reaction to be avoided.
I had this giant hunch when I woke this morning that this reaction has a relatively narrow Goldilocks temperature range; too hot or too cold and it doesn't go. The boiling range of Shellsol D70 may be part of the secret sauce, in that putting it under reflux at its low boiling temperature (200 &deg;C) may put the reaction into its sweet spot.

To all people replicating this, therefore: Please at least measure your temperature. It's too much to ask most of you to use a PID controller, but (again) I'll mention it.

Writing this post up, I realized that the patent contains two clues about how too hot a temperature might diminish the reaction.
• The formation of Mg(OH)2 is more efficient at receiving hydroxyl groups from KOH. Formation of MgO presumably scavenges more of the available Mg, removing its reaction potential with KOH. MgO is promoted by higher temperatures.
• The formation of Mg t-butylate removes two reagents from availability. I haven't looked it up, but I'm guessing that the energy to form the Mg butylate is higher than that to form the K butylate. In this case the higher heat leads away from the desired reaction pathway.

Edit: Added quotation for "reaction accelerator"; those are the words in the patent itself.

[Edited on 7-12-2010 by watson.fawkes]
blogfast25
Thought-provoking Teacher

Posts: 10334
Registered: 3-2-2008
Location: Old Blighty
Member Is Offline

Mood: No Mood

 Quote: Originally posted by ScienceSquirrel That is a recipe for potassium sand, sodium sand is made in a similar way. The solvent is heated up with the metal in it then vigorously shaken or stirred while cooling so the metal remains in very fine particles. The high boiling solvent is then removed under dry argon and replaced with hexane or similar. It is a very reactive reducing and metallating reagent.

The closest you can get to sodium/potassium powder, eh? Interesting: I've found a company some time ago that sold Li powder, I wonder if it's made in similar fashion...
watson.fawkes
International Hazard

Posts: 2793
Registered: 16-8-2008
Member Is Offline

Mood: No Mood

 Quote: Originally posted by blogfast25 Isn’t nearly all size reduced Mg, with the exception perhaps of Rieke metal, formed by stressing the metal? Turnings are achieved by means of various kinds of stresses, filings (as used by pok) mainly shearing forces. Where would you get non-strained but size-reduced Mg? (Apart from Rieke metals).
The nature of the stresses from, say, ball milling Mg are different from that of putting a machine tool on it. Without getting too much into the continuum mechanics, it seems that milling creates a strain with one eigenvalue >1 and one <1 with constant volume, i.e. product = 1. By contrast, milling would tend to strain only one axis, compressing it (eigenvalue <1) and leaving the other axis about the same (eigenvalue ~ 1). I don't know enough of the detailed metallurgy of Mg to defend this hypothesis, but I find it plausible that different manipulations leave different amounts of residual stress.

Perhaps much more important, however, is how recently the machining was done. The passage of time causes annealing, fairly slowly with iron alloys, but I believe much more quickly with Mg. The fact that the Mg filings or turnings are fresh may be the significant factor.
blogfast25
Thought-provoking Teacher

Posts: 10334
Registered: 3-2-2008
Location: Old Blighty
Member Is Offline

Mood: No Mood

 Quote: Originally posted by watson.fawkes I went over the patent last night, to see if I'd notice new things not mentioned yet in this thread. I noted a number of things.The abstract mentions an alcohol as a reaction accelerator. I'm guessing the authors managed to make this work without it, albeit in some commercially impractical way. The authors mention doing the reaction under increased pressure. I know one member here with an autoclave (hint, hint). From a physical chemistry point of view, if this is relevant, it means that this reaction is limited by activation energy, because that's what higher pressure gives you—extra activation energy. The patent states that Mg(OH)2 is formed dehydrating KOH, and that MgO is formed at higher temperatures. Example 1, however, categorically states that the residue was MgO. Is conversion really total? It matters because Mg(OH)2 sequesters more oxygen per mole Mg than does MgO. Example 1 says that potassium t-butylate is left as a residue, which they extract as a solute from 1,4-dioxane. They don't actually state that this is where the rest of the 13% K ends up, and they don't mention if this reside contains any KOH. The residue question is even more interesting in Example 6, where they mention the residue contains Mg butylate. This seems like a bona-fide side reaction to be avoided. I had this giant hunch when I woke this morning that this reaction has a relatively narrow Goldilocks temperature range; too hot or too cold and it doesn't go. The boiling range of Shellsol D70 may be part of the secret sauce, in that putting it under reflux at its low boiling temperature (200 °C) may put the reaction into its sweet spot. To all people replicating this, therefore: Please at least measure your temperature. It's too much to ask most of you to use a PID controller, but (again) I'll mention it. Writing this post up, I realized that the patent contains two clues about how too hot a temperature might diminish the reaction. The formation of Mg(OH)2 is more efficient at receiving hydroxyl groups from KOH. Formation of MgO presumably scavenges more of the available Mg, removing its reaction potential with KOH. MgO is promoted by higher temperatures. The formation of Mg t-butylate removes two reagents from availability. I haven't looked it up, but I'm guessing that the energy to form the Mg butylate is higher than that to form the K butylate. In this case the higher heat leads away from the desired reaction pathway.

Your point 1. I think you’re playing with words here. Isn’t ‘reaction accelerator’ a cautious term for ‘catalyst’? There are many reactions that simply do not proceed without the ‘reaction accelerator’.

Point 2. Increased pressure gives you higher activation energy? Please explain that for the case of an incompressible reaction medium.

Point 3. As indicated above the reaction 2 KOH + Mg --- > 2 K + Mg(OH)2 seems thermodynamically more favourable than 2 KOH + Mg --- > 2 K + MgO + H2O (somewhat to my surprise). According Wiki, Mg(OH)2 only dehydrates at 332C, as len1 also pointed out. And as he he also correctly pointed out, the patent makes some statements that are patently (no pun intended) the result of calculation (or reason, if you prefer) rather than observation (see the 'hydrogen evolved' issue). Their claim on MgO may not have been the result of analysis...

Goldilocks? It’s possible, then pok just hit the jackpot… (jackpok??)

[Edited on 7-12-2010 by blogfast25]
blogfast25
Thought-provoking Teacher

Posts: 10334
Registered: 3-2-2008
Location: Old Blighty
Member Is Offline

Mood: No Mood

Regards stresses in metal ‘powders’, it could possibly explain some strange discrepancies I’ve jotted down over the years with various Goldschmidt (and analogous) reactions.

In the mean time, somewhat disappointingly, no movement at versuchschemie.de on this issue at all...

[Edited on 7-12-2010 by blogfast25]
ScienceSquirrel
Super Moderator

Posts: 1863
Registered: 18-6-2008
Location: Brittany
Member Is Offline

Mood: Dogs are pets but cats are little furry humans with four feet and self determination!

We used to use it to make sodium cyclopentadienide aka NaCp.
This was used to make other substituted cyclopentadienes and then remetallated and then used to make metal complexes.
The sand can be very fine if it is made properly, you just need a bit of nerve and a fast, powerful stirrer. I have seen it made by wrapping the flask in a towel and shaking vigorously while it cooled, that would probably result in a whole litter of Elf and Safety kittens these days.
A description of the process is here;

http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv7...
watson.fawkes
International Hazard

Posts: 2793
Registered: 16-8-2008
Member Is Offline

Mood: No Mood

 Quote: Originally posted by blogfast25 Your point 1. I think you’re playing with words here. Isn’t ‘reaction accelerator’ a cautious term for ‘catalyst’? There are many reactions that simply do not proceed without the ‘reaction accelerator’. Point 2. Increased pressure gives you higher activation energy? Please explain that for the case of an incompressible reaction medium. Point 3. As indicated above the reaction 2 KOH + Mg --- > 2 K + Mg(OH)2 seems thermodynamically more favourable than 2 KOH + Mg --- > 2 K + MgO + H2O (somewhat to my surprise). According Wiki, Mg(OH)2 only dehydrates at 332C, as len1 also pointed out. And as he he also correctly pointed out, the patent makes some statements that are patently (no pun intended) the result of calculation (or reason, if you prefer) rather than observation (see the 'hydrogen evolved' issue). Their claim on MgO may not have been the result of analysis...
1. The words "reaction accelerator" were in the original; I've edited my original post to make that clearer. My point is that it's possibly that the author may have managed to make this work without a catalyst at all, possibly under pressure.

2. Increased pressure is a source of free energy to overcome activation energy. I should have worded that more carefully. Pressure is just a kind of energy per unit volume. Microscopically, it's from electron clouds not wanting to overlap (both electrostatically and from Pauli exclusion).

3. Mg(OH)2 is thermodynamically favorable simply because its dehydration to MgO is endothermic. Nevertheless, it seems that MgO might be kinetically favorable at higher temperatures. If so, that would make the claim of the authors I discussed realistic. It would also entail that Mg(OH)2 is kinetically favorable at lower temperatures, meaning the process as a whole might not work well if you get it too hot.

The 332 &deg;C temperature is for a solid phase decomposition. That's only one possible pathway and it puts an upper temperature bound on what other pathways would be observable. It doesn't exclude other pathways, though.

I do agree that the examples have a certain amount of idealization in them. The degree of it, however, does not rise to lead me to believe that they were entirely fabricated from whole cloth. My working model of what's going on there is commercial obfuscation rather than patent fraud.
Pages:  1  ..  4    6    8  ..  66

 Sciencemadness Discussion Board » Fundamentals » Chemistry in General » Make Potassium (from versuchschemie.de) Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues   » Detritus   » Test Forum