Percarbonate Compounds

Peroxycarbonates (also known as peroxocarbonates) play an important role in the synthesis of plastics, for example in the production of PVC or PE. Many heavy-duty detergents contain percarbonates as bleaching substances.

Peroxy(di)carbonates contain bound peroxides

The underlying peroxycarboxylic acid H2CO4 is not stable and rather hypothetical, but there are the anions HCO4 and CO42-, which are present in sodium peroxycarbonate.

The two corresponding anions of peroxycarboxylic acid
The two corresponding anions of peroxycarboxylic acid

There are also sodium peroxydicarbonates with the anion C2O62-.

Peroxydicarboantes can be formed by the electrolysis of carbonates:

2 CO32- —> C2O62- + 2 e (Anode)

When in contact with water, peroxy(di)carbonate anions easily convert to normal carbonate CO32- ions. In this process hydrogen peroxide is split off.

HCO4 + H2O —> HCO3 + H2O2

CO42- + H2O —> CO32- + H2O2

C2O62- + 2 H2O —> 2 HCO3 + H2O2

During the synthesis of plastics, sodium peroxydicarbonate breaks down into two radicals as the peroxo bridge is split homolytically.

C2O62-  —> 2 CO3

These radicals start the polymerization of monomer molecules in the synthesis of plastics.

Sodium percarbonates are peroxohydrates

However, these are only hydrate-like H2O2 adducts, like 2 Na2CO3 • 3 H2O2. The exact name for the group is sodium carbonate peroxohydrate.

They disintegrate in water with the formation of carbonate as well as oxygen and hydroxyl radicals. These have a bleaching effect, which is why percarbonates are added to detergents instead of peroxoborates. Unlike perborates, sodium percarbonate does not have a harmful effect on the environment.