Orthocarbonic acid


Orthocarbonic acid is the name given to a hypothetical compound with the chemical formula H4CO4 or C4. Its molecular structure consists of a single carbon atom bonded to four hydroxy groups. It would be therefore a fourfold alcohol. In theory it could lose four protons to give the hypothetical oxocarbon anion , and is therefore considered an oxoacid of carbon.
Orthocarbonic acid is highly unstable. Calculations show that it decomposes spontaneously into carbonic acid and H2O:
Orthocarbonic acid is one of the group of carboxylic ortho acids that have the general structure of RC3.The term ortho acid is also used to refer to the most hydroxylated acid in a set of oxoacids.
Researchers at the Moscow Institute of Physics and Technology predict that orthocarbonic acid is stable at high pressure; hence it may form in the interior of planets.

Orthocarbonate anions

By loss of one through four protons, orthocarbonic acid could yield four anions:,,, and .
As of 2002, salts of these anions had yet to be observed. However, theoretical studies suggest that Na4CO4 might be stable.

Orthocarbonate esters

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