In
chemistry, peroxydicarbonate (sometimes peroxodicarbonate) is a
divalentanion with the chemical formula C 2O2− 6. It is one of the
oxocarbon anions, which consist solely of
carbon and
oxygen. Its molecular structure can be viewed as two
carbonate anions joined so as to form a
peroxide bridge –O–O–.
In addition, the peroxodicarbonate anion can be obtained by
electrosynthesis on
boron doped diamond (BDD) during water oxidation.[3][4] The formal
oxidation of two carbonate ions takes place at the anode. Due to the high oxidation potential of the peroxodicarbonate anion, a high anodic overpotential is necessary. This is even more important if
hydroxyl radicals are involved in the formation process. Recent publications show that a concentration of 282 mmol/L of peroxodicarbonate can be reached in an undivided cell with
sodium carbonate as starting material at current densities of 720 mA/cm2.[5] The described process is suitable for the pilot scale production of sodium peroxodicarbonate.
Potassium peroxydicarbonate K2C2O6 was obtained by
Constam and
von Hansen in 1895;[6] its crystal structure was determined only in 2002.[7] It too can be obtained by electrolysis of a saturated potassium carbonate solution at −20 °C. It is a light blue crystalline solid that decomposes at 141 °C, releasing
oxygen and carbon dioxide, and decomposes slowly at lower temperatures.[7]
Rubidium peroxodicarbonate is a light blue crystalline solid that decomposes at 424 K (151 °C). Its structure was published in 2003.[2] In both salts, each of the two carbonate units is planar. In the
rubidium salt the whole molecule is planar, whereas in the
potassium salt the two units lie on different and nearly perpendicular planes, both of which contain the O–O bond.[2]
^Chen, Li-Jiang; Lin, Chang-Jian; Zuo, Juan; Song, Ling-Chun; Huang, Chao-Ming (2004). "First Spectroscopic Observation of Peroxocarbonate/ Peroxodicarbonate in Molten Carbonate". The Journal of Physical Chemistry B. 108 (23): 7553–7556.
doi:
10.1021/jp035749l.
^
abcDinnebier, Robert E.; Vensky, Sascha; Jansen, Martin (2003). "Crystal and Molecular Structure of Rubidium Peroxodicarbonate Rb2[C2O6]". Chemistry: A European Journal. 9 (18): 4391–4395.
doi:
10.1002/chem.200304914.
PMID14502625.