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mad.gif posted on 11-4-2005 at 18:22
Melting Lithium


What would be the best way to melt lithium foil into lithium chuncks/bars? Neither steel or graphite crucibles work.



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[*] posted on 11-4-2005 at 18:27


What do you mean by 'they don't work'? Do they fall apart/melt/burn?

Whatever you do, don’t use an oxide-based material (glass, porcelain, etc.) Liquid Li will react with just about anything it can, rather violently, too. You don't want a thermite reaction on your hands.
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[*] posted on 11-4-2005 at 18:46


Lithium reacts with graphite to form some sort of lithium carbide. In a steel crucible the lithium forms a hard, less reactive chunck that I couldn't get off the steel. Also, once I was reacting lithium in water in a plastic bottle, it actually caught on fire and burned with the plastic.:o



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[*] posted on 12-4-2005 at 02:15


It sounds like it's reacting with air. Maybe add a cap to your crucibles?
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[*] posted on 12-4-2005 at 04:23


I had a cap on my crucibles. My problem is that the lithium 'wets' the steel crucible.
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[*] posted on 12-4-2005 at 05:24


How about covering the crucible in a layer of powdered lithium chloride or magnesium oxide? Or even using the ground materials to 'sand cast' the lithium as with iron?
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[*] posted on 12-4-2005 at 06:00


Wont it thermite with the magnesium oxide?



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[*] posted on 12-4-2005 at 10:47


Quote:
Originally posted by Saerynide
Wont it thermite with the magnesium oxide?


You'd think so, but MgO is more stable than Li2O. I seem to recall someone obtained some useful metal this way.

Tim
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[*] posted on 12-4-2005 at 11:41


A little bit out of topic but would an alkane gas, such as butane, be unreactive towards lithium? I was planning a molten state electrolysis of lithium chloride under a butane environment, totally absent of air, although not in the near future. Butane would be a cheap alternative, it can be dried by passage through conc. sulfuric acid. Would CO also be unreactive towards lithium?



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[*] posted on 12-4-2005 at 12:04


Butane will work, it is actually a very good idea.
The butane from the can is already dry enough, no drying is necessary.
CO reacts with potassium to form the potassium salt of hexahydroxybenzene, maybe something similar happens with lithium? I wouldn't use it as a protective gas.
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[*] posted on 12-4-2005 at 12:14


Thanks for the help. I am going to try the extraction using apparatus similar to that I am trying to set-up for an electrochemical extraction of sodium from the hydroxide, in which case I will either use butane or nitrogen gas.



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[*] posted on 12-4-2005 at 14:23


Another problem is that whenever molten lithium comes in contact with lithium it starts burning vigorously. So much for that lithium.:mad: I currently do not have inert gas melting capabilities.



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[*] posted on 12-4-2005 at 14:58


Maybe try using an oil to coat the inside of your steel vessel. Lithium suspensions can be made in mineral oil and it has a very high boiling point and should be able to stand molten lithium in it. Just a little coated on the inside of the crucible might work.



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[*] posted on 12-4-2005 at 15:18


"CO reacts with potassium to form the potassium salt of hexahydroxybenzene". This would involve aromaticization, which normally requires pressure on gas-phase unsaturated carbon compounds. Have you a reference for this?

BTW hydrolysis of this salt to hexahydroxybenzene could, in theory, be a route to a powerful explosive, by subsequent esterification with nitric acid, in the form of the hexanitrate, C(NO3)6.
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[*] posted on 12-4-2005 at 16:43


There are plenty. I read it elsewhere too, but can't remember where.
JohnWW, the man of knowledge never heard of this? How disappointing :P

http://www3.interscience.wiley.com/cgi-bin/abstract/10973052...

Edit: Forming the hexanitrateester??
The question is, does this behave as a hexa acid or a hexabase? Looks like a very weak base. Doubt it would be possible by direct nitration.
Also I seem to remember that the hexahydroxybenzene salt is explosive.

[Edited on 13-4-2005 by chemoleo]




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[*] posted on 13-4-2005 at 01:09


Oops, that hexanitrate (from hexahydroxybenzene) formula I speculated should be C6(NO3)6.

No wonder I did not know of that reference Chemoleo gave; its title is in German, which imposed difficulty in searching for it, although the body of the abstract is in English. It reads:-

"Zur Kenntnis der sogenannten «Alkalicarbonyle» IV [1]. Über die Reaktion von geschmolzenem Kalium mit Kohlenmonoxid
W. Büchner, E. Weiss
Cyanamid European Research Institute, Cologny/Genf

Die Zahlen in eckigen Klammern verweisen auf das Literaturverzeichnis, S. 1423.

Abstract
The reaction between molten potassium and carbon monoxide (without solvent) has been studied. The reaction products obtained have been shown to be a mixture of potassium acetylenediolate, an organometallic compound, and the potassium salt of hexahydroxybenzene, the relative amounts of which vary with temperature. At reaction temperatures near the melting point of potassium (62,3°), potassium acetylenediolate and the organometallic compound are the major products, whereas at temperatures higher than 180° the potassium salt of hexahydroxybenzene predominates."

The abstract does not say what pressure was applied, unfortunately, which would have a profound effect on the reaction. The acetylenediolate ion produced as a competing product would presumably be the dimeric form -O-C[triplebond]C-O- . The unidentified other so-called "organometallic" product may be a salt with the free-radical anion •C[triplebond]O- , which would certainly tend to polymerize to the hexahydroxybenzenide anion, especially under pressure. Or perhaps the potassium reduces some of the CO to carbon and forms the graphite salt in which the K+ ions are in layers between sheets of carbon atoms, with some of the K being oxidized to K2O, K2O2, and KO2.

As regards reactions of phenols with HNO3: if there are places available on the ring occupied by something removable like H, the tendency is for ortho- and para-nitration with -NO2 groups. However, esterification of phenols with strong acids like HNO3 would require much more severe conditions, unlike esterification of aliphatic alcohols, because of the greater acidity of phenolic -OH groups; and would require other sites on the ring to be "blocked" to nitration (to form -NO2 groups), which happens to be the case with hexahydroxybenzene. And the -OH groups on hexahydroxybenzene would be substantially more acidic than that of C6H5OH; it might work with pentamethylphenol. In addition, more severe conditions with HNO3, or anhydrous nitronium salts, might result in oxidation to a quinone derivative.

But if the hexanitrate could be obtained somehow, it would be a marvellously powerful explosive.
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