Sciencemadness Discussion Board

Mellitic acid

libavius - 21-11-2009 at 08:14

Anyone knows the method to produce (oxidize) the carbon to Mellitic acid?
I had read it somewhere but now I can not find the procedure.
Thanks!

JohnWW - 21-11-2009 at 19:43

I have read somewhere of the stuff, formula C6(COOH)6, being made by oxidizing graphite or hexamethylbenzene with hot concentrated HNO3 or alkaline KMnO4. This has been in a thread here somewhere before. It was first discovered in 1799 in the mineral mellite (honeystone), which is the aluminium salt of the acid, and which is produced when strongly acid waters caused by oxidation of sulfide minerals buried in clays, thereby containing Al in solution, come into contact with coal.

The free acid was first 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.

Its anhydride, C12O9, obtained by heating the acid, contains no H and is so an oxide of carbon.

For further info about its properties, see http://en.wikipedia.org/wiki/Mellitic_acid and http://en.wikipedia.org/wiki/Mellitic_acid


200px-Mellitic-acid-anhydride.png - 14kB

[Edited on 22-11-09 by JohnWW]

200px-Mellitic-acid.png - 14kB

not_important - 22-11-2009 at 00:20
Quote:
Electrochemical oxidation of graphite anode in deionized water at galvanostatic mode is investigated. It is found that mellitic acid and graphite oxide colloid (>20 nm) are coexisted as main products, as identified by XRD and TEM, FTIR and XPS. They can be separated successfully through several procedures. A few amounts of graphene and graphene rolls are also appeared as co-products.

http://dx.doi.org/10.1016/j.elecom.2008.12.003


http://www.osti.gov/energycitations/product.biblio.jsp?osti_...

Mellitic Acid from the Oxidation of Graphite with 90% Nitric Acid.
http://pubs.acs.org/doi/abs/10.1021/je60022a027

Mellitic Acid from Coals, Cokes and Graphites
http://pubs.acs.org/doi/abs/10.1021/ja01280a052

somewhat related
PYROMELLITIC ACID
http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv2...


also use this site's search function, I believe that the topic has been discussed before.


libavius - 22-11-2009 at 06:04

Thanks JohnWW, thanks Not_important, you were very useful for me.
I knew that was a synthesis difficult, but I expected a better yield!
Perhaps the one only slightly executable will Pyromellitic acid.
Bye

chemoleo - 22-11-2009 at 08:20

And how would one best reduce this to the cyclohexane version (hexacarboxycyclohexane)?
Birch reduction - not even sure if that would work, and in any case one would get the diene version.
Looks like metal catalyst, i.e. Pd/H?

sparkgap - 22-11-2009 at 08:34

Using rhodium as the catalyst (or still plain Pd but with really high pressure) would definitely reduce the benzene ring to cyclohexane; as to whether the carboxyls will survive that treatment unreduced (to the alcohol, that is) is what I ain't too sure about.

sparky (~_~)