Orthocarbonic acid

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Orthocarbonic acid
Stereo skeletal formula of orthocarbonic acid Ball and stick model of orthocarbonic acid
CAS number 463-84-3 N
PubChem 9547954
ChemSpider 7826887 YesY
Jmol-3D images Image 1
Molecular formula CH4O4
Molar mass 80.04 g mol−1
Related compounds
Related compounds Dihydroxymethylidene

Silicic acid

Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Orthocarbonic acid or methanetetrol is the name given to a hypothetical compound with the chemical formula H4CO4 or C(OH)4. Its molecular structure consists of a single carbon atom bonded to four hydroxyl groups. It would be therefore a fourfold alcohol. In theory it could lose four protons to give the hypothetical oxocarbon anion CO44− (orthocarbonate), and is therefore considered an oxoacid of carbon.

Orthocarbonic acid is highly unstable, decomposing spontaneously into carbonic acid monohydrate:[2][3]

H4CO4 → H2CO3 + H2O.

Orthocarbonic acid is one of the group of carboxylic ortho acids that have the general structure of RC(OH)3.The term ortho acid is also used to refer to the most hydroxylated acid in a set of oxoacids.

Orthocarbonate anions[edit]

By loss of one through 4 protons, orthocarbonic acid could yield four anions: H3CO4, H2CO42−, HCO43−, and CO44−.

As of 2002, salts of these anions had yet to be observed. However, theoretical studies suggest that Na4CO4 might be stable.[4]

Orthocarbonate esters[edit]

The tetravalent moiety CO4 is found in stable organic compounds; they are formally esters of orthocarbonic acid, and therefore are called orthocarbonates. For example, ethyl orthocarbonate can be prepared by the reaction between chloropicrin and sodium ethoxide in ethanol.[5] Polyorthocarbonates are stable polymers that might have applications in absorbing organic solvents in waste treatment processes,[6] or in dental restorative materials.[7]


  1. ^ "Methanetetrol - PubChem Public Chemical Database". The PubChem Project. USA: National Center for Biotechnology Information. 
  2. ^ S. Bohm, D. Antipova, J. Kuthan (1997) "A Study of Methanetetraol Dehydration to Carbonic Acid". International Journal of Quantum Chemistry, volume 62, pages 315–322 doi:10.1002/(SICI)1097-461X(1997)62:3<315::AID-QUA10>3.3.CO;2-N
  3. ^ Carboxylic Acids and Derivatives IUPAC Recommendations on Organic & Biochemical Nomenclature
  4. ^ Musstafa Al-Shemali and Alexander I. Boldyre (2002), "Search for Ionic Orthocarbonates: Ab Initio Study of Na4CO4". J. Phys. Chem. A, volume 106, issue 38, pages 8951–8954 doi:10.1021/jp020207+
  5. ^ Orthocarbonic acid, tetraethyl ester Organic Syntheses, Coll. Vol. 4, p.457 (1963); Vol. 32, p.68 (1952)
  6. ^ Sonmez, H.B.; Wudl, F. (2005). "Cross-linked poly (orthocarbonate) s as organic solvent sorbents". Macromolecules 38 (5): 1623–1626. doi:10.1021/ma048731x'). 
  7. ^ Stansbury, J.W. (1992). "Synthesis and evaluation of new oxaspiro monomers for double ring-opening polymerization". Journal of Dental Research 71 (7): 1408–1412. doi:10.1177/00220345920710070901. PMID 1629456. Retrieved 2008-06-19.