Mellitic acid
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2008-06-23T23:49:02Z
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{{Chembox new
| Name = Mellitic acid
| Reference =<ref>[http://msds.ourlib.org/Msds_Detail.asp?id=5184&pname=Mellitic%20acid,%2099%25&cas=517-60-2&Synonym=&page=130 MSDS for mellitic acid]</ref>
| ImageFile = Mellitic-acid.png
<!-- | ImageSize = 200px -->
| ImageName =
| IUPACName = Benzene-1,2,3,4,5,6-hexacarboxylic acid
| OtherNames = Graphitic acid<br />Benzene hexacarboxylic acid
| Section1 = {{Chembox Identifiers
| CASNo = 517-60-2
| SMILES = O=C(O)C1=C(C(O)=O)C(C(O)=O)<br />=C(C(O)=O)C(C(O)=O)=C1C(O)=O
}}
| Section2 = {{Chembox Properties
| Formula = C<sub>12</sub>H<sub>6</sub>O<sub>12</sub>
| MolarMass = 342.16 g/mol
| Density = 1.68 g/cm<sup>3</sup>, 2.078 (calc.)<ref name=spider>[http://www.chemspider.com/RecordView.aspx?id=2244 Curate Data: Predicted Properties: 2244]. ChemSpider.com.</ref>
| MeltingPt = >300 °C
| BoilingPt = 678 °C (calc.)<ref name=spider/>
| }}
}}
'''Mellitic acid''', also called '''graphitic acid''', '''benzene hexacarboxylic acid''', and '''benzene-1,2,3,4,5,6-hexacarboxylic acid''' (IUPAC name) is an [[acid]] first discovered in [[1799]] by [[Martin Heinrich Klaproth|M. H. Klaproth]] in the [[mineral]] [[mellite]] (honeystone), which is the [[aluminium]] [[salt]] of the acid.
==Preparation==
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 [[precipitate]]d [[alumina]] is filtered off, the [[filtrate]] [[evaporate]]d 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]].<ref>[http://www.webelements.com/webelements/elements/text/C/chem.html WebElements.com]</ref>
==Reactions==
It crystallizes in fine silky needles and is soluble in [[water]] and [[alcohol]]. It is a very stable compound, [[chlorine]], concentrated [[nitric acid]] and [[hydriodic acid]] having no action upon it. It is decomposed, on dry distillation, into [[carbon dioxide]] and [[pyromellitic acid]], C<sub>10</sub>H<sub>6</sub>O<sub>3</sub>; when distilled with [[lime (mineral)|lime]] it gives carbon dioxide and [[benzene]]. Long digestion of the acid with excess of [[phosphorus pentachloride]] results in the formation of the acid chloride, which crystallizes in needles, melting at 190 °C. By heating the ammonium salt of the acid to 150-160 °C as long as ammonia is evolved, a mixture of paramide (mellimide), C<sub>6</sub>(CONH)<sub>3</sub>, and [[ammonium euchroate]] is obtained. The mixture may be separated by dissolving out the ammonium euchroate with water. Paramide is a white amorphous powder, insoluble in water and alcohol.
The high stability of mellitic acid salts and that they are the endproduct of the oxidation of [[polycyclic aromatic hydrocarbon]]s, which are present in the solar system, made them a possible organic substance in [[Mars|Martian]] soil.<ref>{{cite journal
| author = S. A. Benner, K. G. Devine, L. N. Matveeva, D. H. Powell
| year = 2000
| title = The missing organic molecules on Mars
| journal = [[Proceedings of the National Academy of Sciences]]
| volume = 97
| issue = 6
| pages = 2425–2430
| doi = 10.1073/pnas.040539497
| pmid = 10706606
}}</ref>
==Mellitic anhydride==
[[Image:Mellitic-acid-anhydride.png|thumb|120px|right|Mellitic acid anhydride]]
The [[Acid anhydride|anhydride]] of mellitic acid, C<sub>12</sub>O<sub>9</sub>, is one of the exotic oxides of carbon as it only consists of carbon and oxygen like the other oxides [[carbon dioxide|CO<sub>2</sub>]], [[carbon monoxide|CO]], [[Carbon suboxide|C<sub>3</sub>O<sub>2</sub>]] and [[dicarbon monoxide|C<sub>2</sub>O]].<ref>{{cite journal
| author = Meyer H, Steiner K
| year = 1913
| title = A new carbon oxide C<sub>12</sub>O<sub>9</sub>
| journal = [[Chemische Berichte|Berichte der Deutschen Chemischen Gesellschaft]]
| volume = 46
| pages = 813–815
}}</ref>
==References==
<references/>
===Further reading===
Henry Enfield Roscoe, Carl Scholemmer, "Mellitene Group", "''[http://books.google.com/books?id=4LIEAAAAYAAJ&pg=PA373&lpg=PA373&dq=mellitic&source=web&ots=B5lVM-UdyO&sig=qzTdUZwifSfjXt5zfSJ170aepsE A Treatise on Chemistry]'': ''V.III: The Chemistry of the Hydrocarbons and their Derivatives on Organic Chemistry: P.V'':529. D. Appleton and Co. (1889).
{{1911}}
[[Category:Carboxylic acids]]
[[Category:Benzoic acids]]
[[Category:Aromatic compounds]]
[[lv:Melitskābe]]
[[ja:メリト酸]]