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Author: Subject: Mellitic Acid Synthesis and Properties
StevenRS
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[*] posted on 18-7-2008 at 19:21
Mellitic Acid Synthesis and Properties


I heard about this acid a long time ago, and suddenly remembered about it, with a sudden urge to make it and test its properties.

From the very little amount of data available on this acid, I have learned that it is actually not impossible to make! But I still have no idea how to make it with reasonable yield, so any help would be appreciated.

Other than its relative unreactivity, I have also found very little details on its properties, physical or chemical.

For anyone who does not know what it is, it is an exotic oxide of carbon, and its formula is C12O9 (anhydrous).

Being an acid, I would assume it is ionic, and disassociates in water, forming a conductive solution, but what would the ions be? If electrolyzed, would it produce graphite and water?

If it could form salts, what would be their properties???

For synthesis, my guess is a very strong acid with a very strong oxidizer, like a chlorate and nitric acid, or something along those lines attacking carbon powder, maybe lampblack or activated carbon.

Any thoughts?

EDIT: I found this, but I have no mellite.

Mellitic acid may be prepared by warming mellite with ammonium carbonate, boiling off the excess of the ammonium salt and adding ammonia to the solution. The precipitated alumina is filtered off, the filtrate evaporated and the ammonium salt of the acid purified by recrystallization. The ammonium salt is then converted into the lead salt by precipitation with lead acetate and the lead salt decomposed by hydrogen sulfide. The acid may also be prepared by the oxidation of pure carbon, or of hexamethyl benzene, in the cold, by alkaline potassium permanganate, or by hot concentrated nitric acid.[3]

[Edited on 18-7-2008 by StevenRS]
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[*] posted on 18-7-2008 at 19:46


I seem to recall the first proton is rather acidic (nearly strong). I don't remember if I saw that factually somewhere or if I just extrapolated it. That would assume that the aid doesn't dehydrate in solution, which I bet it would at that pH..

Complete reduction would give hexamethylbenzene, just as complete oxidation of same gives mellitic acid. If it polymerized to a large extent on reduction, it could give graphite. Probably, something like a 1:1 mixture of methanol and aldehyde groups would dehydrate nicely to an amorphous, carbonaceous resin of sorts.

But yeah, as for synthesis, I don't know. I do know graphite, after electrolyzing for a few hundred amp-hours, gets distinctly hydrophilic. For sure, it's being functionalized, how much I don't know. It's a surface effect, and due to the granular structure, soon spalls off as granular graphite muck. I guess it's worth a try throwing some hot and heavy oxidizers at it and seeing what happens.

Tim




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[*] posted on 18-7-2008 at 21:17


Electrolytic oxidation of carbon produces most of the higher members of the poly-carboxylic-benzene family.

Oxidation of carbon is the general royte, yields vary greatly depending on the particular carbon source used. Some charcoals give zero yield, others a decent amount. Many carbon sources also yield the penta and quad acids along with oxalic acid.

It's also known as graphitic acid, the anhydride as graphitic oxide; although those also are as names of modified graphites or poly-aromatic homologs of mellitic acid

decent description of properties of the acid and a number of salts is at A Treatise on Chemistry by H.E. Roscoe & C. Schorlemmer :

http://books.google.com/books?id=4LIEAAAAYAAJ&pg=PA373&a...

U.S. patents 2176348 and 2798878 are methods of preparing mellitic acid, the 2nd includes a number of references to earlier literature on mellitic acid.
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JohnWW
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[*] posted on 18-7-2008 at 21:18


I think I remember reading somewhere about mellitic acid being made by the action of hot concentrated nitric acid on graphite, under certain conditions. This is confirmed by http://en.wikipedia.org/wiki/Mellitic_acid , which gives alkaline KMnO4 as an alternative oxidant, and hexamethylbenzene as an alternative substrate. . However, hexanitrobenzene, or hexamethylnitrobenzene, are other possible products. Actually it is mellitic anhydride that is the oxide of carbon with formula C12O9, or C6(C2O3)3. The acid itself is C6(COOH)6.

Other references are:
http://www.answers.com/topic/mellitic-acid
http://www.1911encyclopedia.org/Mellitic_Acid
http://www.freepatentsonline.com/2176348.html
http://www.freepatentsonline.com/2250204.html
http://encyclopedia.jrank.org/MEC_MIC/MELLITIC_ACID_benzene_...
http://www.nature.com/nature/journal/v185/n4715/abs/185756a0...
http://scripts.iucr.org/cgi-bin/paper?a03023
http://encarta.msn.com/mellitic%2Bacid.html

Inclusions of mellitic acid have been found in coal deposits which have been subjected to heating and acid waters, which could happen if volcanic lava comes into contact with coal. It was first discovered in 1799 as the mineral mellite, which is the aluminium salt.
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[*] posted on 18-7-2008 at 23:19


Graphitic acid is explosive.

"Carbon from Graphitic Acid.-When graphitic acid is heated it explodes with the formation of a large volume of an extremely finely divided and fluffy material described in the literature as amorphous carbon." JACS, 45, 572 (1923)

Attachment: Mellitic Acid from Coals, Cokes and Graphites - JACS, 59 (1937).pdf (663kB)
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ShadowWarrior4444
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[*] posted on 19-7-2008 at 01:44


I wonder if it would be possible to form an ester with Diacetone Alcohol, then peroxidate it. That might be a particularly interesting explosive.

(Or any number of other similar procedures to form novel explosives, or aesthetically pleasing organic molecules.)

[Edited on 7-19-2008 by ShadowWarrior4444]




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StevenRS
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[*] posted on 19-7-2008 at 16:05


I tried the cold, alkaline KMno4 method, and it did not work. I started with 5g of carbon powder, and ended up with the same. I will try it with other sources of carbon, and then I will try nitric acid.
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[*] posted on 19-7-2008 at 16:30


I think cold KMnO4 was meant with the hexamethylbenzene. I don't see anything non-electrolytic attacking graphite in the cold, well maybe ozone.

Tim




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[*] posted on 20-7-2008 at 09:39


Brauer has a preparation of "Graphite oxide" which probably contains a decent amount of mellitic acid. Page 638.



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