In organic chemistry, a dicarbonate, also known as a pyrocarbonate, is a compound containing the divalent [-O-(C=O)-O-(C=O)-O-] or C
52• functional group, which consists of two carbonate groups sharing an oxygen atom. These compounds can be viewed as double esters of a hypothetical dicarbonic acid, H
5 or HO-(C=O)-O-(C=O)-OH. Two important examples are dimethyl dicarbonate H3C-C2O5-CH3 and di-tert-butyl dicarbonate (H3C-)3C-C2O5-C(-CH3)3.
The term "dicarbonate" is sometimes used erroneously to refer to bicarbonate, the common name of the hydrogencarbonate anion [HCO3]− or organic group [HCO3-].