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Author: Subject: Galinstan keeps dissolving in distilled water ...???
Googolplex
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[*] posted on 5-7-2017 at 12:47
Galinstan keeps dissolving in distilled water ...???


Hi Guys,

Can somebody explain this?

I'm interested in the Galinstan/Al reduction reaction of nitromethane. So I bought 10g of Galinstan on ebay. I made a 50/50 amalgame with standard kitchen Al-foil, this works great (I first tried to make it with thick aluminium, that kind you can use on you BBQ or put chinese food in , but this stuff didn't do anything ...).

After some stirring I had a nice paste of 10g Galinstan and 10g aluminium. Now I had put it in some distilled water to see if it would generate some hydrogen gas. And yes it did!! I also timed the reaction because I wanna see how long it would react. The first 20 min where very vigorously, Than it kept bubbling more but at a lower rate for some 20 min.

After 50 minutes there was a large glossy Galinstan blob on the bottom of the cup. It was still fizzing but not as vigorous as before. So I decanted the galium of, and washed it with some distilled water in the new beaker. After adding the distilled water it was fussing some more again.

I thought there was still some aluminium left in it that was reacting, so I left it alone for 1 hour. When I came back the water was more grey as before with some pieces floating in it. The Galinstan was still slight buzzing but now it was 1/3 of the size as when I left it ...? The Galinstan was going in solution!?!?

Everywhere I read that at the end of the reaction you recuperate almost 100% of your Galinstan. Not in my case ...??? after decanting and washing the Galinstand I was left with no more that 3g of Galinstan (this is a 70% loss ...!!!). I tried to dry it a little bit with the tipof a paper towel and put it in a little vial. Now it looks like a pasty black and white oxidatet piece of crap.

Does anybody know whats is happening here? Am I missing a step to get my Galinstran back???

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Melgar
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[*] posted on 5-7-2017 at 21:07


Did you throw the sludge away from the first time you reacted it yet? I hope not, because I bet that's where most of it is. When it reacts very quickly like that, it'll throw off bits and pieces of galinstan too. When you thought it was dissolving it really WAS just aluminum dissolving, it's just that the blob was more aluminum than you probably realized. Also, check out my thread in the Prepublication forum, I make an alloy with it, and use that for organic reduction. The alloy is convenient because it'll break itself up into pieces the size of grains of sand, since the gallium, tin, and indium deposit along grain boundaries. I'm finding that it works better to use a 10:1 or 8:1 ratio though, since otherwise you usually have unreacted aluminum, and more sludge.

If you're buying from the eBay store I think you are, it's overpriced; I'll sell it for $0.50 a gram. I have quite a bit.

If you want to get it off the inside of a container, put some VERY diluted hydrochloric acid in the container and shake it up really well. It'll eventually form a round blob.




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[*] posted on 6-7-2017 at 01:39


Quote: Originally posted by Melgar  
Did you throw the sludge away from the first time you reacted it yet? I hope not, because I bet that's where most of it is.


Thank for your reply Melgar! Yes, unfortunately I threw it all away. At first I thought it was aluminium sludge. I also didn't had a good separate container to collect it in so i threw it away. When I noticed it was shrinking in size and weight far under the 10g I already regret it that I throw it away :(.

So If I would do this again and the galinstan is throwing away some pieces. Do I just wait until they sink to the bothem and merge again with the big blob at the bottom of the beaker? Are what should I do?

I think I already read most of your treats on Galinstan on this forum. They were very helpful, thanks! Next time I'm gonna melt the aluminium with a torch and add 5% galinstan as you described in the "Prepublication Forum" tread. I didn't have a crucible. Yesterday I order one from Aliexpress, so I should have it in 14 days.

For less sludge and unreacted aluminium you give the ratio 10:1 - 8:1, by which you mean Al/Galinstan, not Galistan/Al, em I right?

If you would do a reduction reaction with nitromethane and a ketone do you drop the amalgame in it all at once, or do you split it in different editions throughout the reaction?

[Edited on 6-7-2017 by Googolplex]
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[*] posted on 6-7-2017 at 07:21


To reclaim it from the sludge, add hydrochloric acid slowly to the sludge to dissolve it, but try to add only as much as you need to and not more than that. When it becomes clear, add some aluminum, preferably with a low surface area to limit how fast it reacts. The aluminum should dissolve, but in the process, pull gallium, indium, and tin out of solution, eventually forming a liquid blob itself.

Yes, that's what I meant by ratio. If you're trying to make drugs, don't. You're not ready, first of all, and easily-obtained ketones like acetone and MEK don't work very well for reductive amination. Try an aldehyde instead, like vanillin or benzaldehyde, to make n-methyl benzylamines.

Also, for a solvent, ethanol works best, with a small amount of water. Everclear is probably the best solvent to use, of the ones I've tried. Methanol and isopropanol work too, but for any really important reactions, ethanol is the way to go.




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[*] posted on 6-7-2017 at 08:56


Quote: Originally posted by Melgar  
To reclaim it from the sludge, add hydrochloric acid slowly to the sludge to dissolve it, but try to add only as much as you need to and not more than that. When it becomes clear, add some aluminum, preferably with a low surface area to limit how fast it reacts. The aluminum should dissolve, but in the process, pull gallium, indium, and tin out of solution, eventually forming a liquid blob itself.


This morning I started again by putting the Galinstan back in a beaker with distilled water. Now 8 hours later its still fizzing. I already have filtered of quite some light grey sludge (Al(OH)3 + galinstan presumably, ).So gallium, indium, and tin also get oxidized in small amounts (I didn't know this.)? Can you explain this reaction mechanism, this is not so clear.? I'm gonna try your techniek, thanks for the information.

And I'm not making drugs. I'm a chemist from education but it has been a few years, I regret that I'm not working in the field and that all my knowledge that i had from chemistry is fading away. So I'm trying to pick it back up piece by piece. At school I did plenty reduction reaction with the Hg/Al amalgam. But we never did it whit gallium/galinstan. At that time it was more expensive.

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[*] posted on 6-7-2017 at 13:39


Of the metals in galinstan, gallium is the most reactive, but its reactivity in distilled water is similar to but less than aluminum. It'll gradually form an oxide coating on its surface, and stop at that. Indium is essentially nonreactive to water, and so is tin. The bubbles you're seeing are from residual aluminum still. It takes a long time for it all to dissolve because of how slowly it diffuses through the alloy, and because of the oxide layer that gallium will form on its surface. You can speed that up by adding a small amount of acid or sodium hydroxide, or you could heat it up. Gallium dissolves in either, but much more slowly than aluminum. I tried to dissolve a gram or so of gallium in sodium hydroxide, but had to give up after a few weeks because of how slow it was at room temperature. In your case though, any aluminum left in the alloy will preferentially reduce gallium salts rather than reduce water, so any acid or alkali will just speed up that process.



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[*] posted on 10-7-2017 at 05:47


I tried your method to recover the Galinstan and it worked great ;). Thanks!!

First I added a diluted HCl solution to the galinstan blob, after 30 minutes it stops fizzing. Than I collected all the sludge (Al(OH)3 + Galinstan) by filtration, dissolved it in concentrated HCl until it was a clear solution. After adding aluminium foil balls piece by piece in a course of 45 min until no more aluminium would dissolve, there was a tiny Galinstan pearl in the bottom of the beaker.

I also tried to recover the AlCl3 by evaporation, cooling, filtration, air drying (100°C). This wassend a success because after filtration I had put the AlCl3 still on the filter paper (coffee filter) in the oven. After it was dry the AlC3 has been suckt up in to the filter paper and was now like a crumble mess af paper and AlCl3. So next time I'm gone dry the AlCl3 on A watch glass :D.

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