Tetraoxidane

Tetraoxidane is an inorganic compound of hydrogen and oxygen with the chemical formula H
₂O
₄.^[1][2][3] This is one of the unstable hydrogen polyoxides.^[4]

Tetraoxidane

Names
IUPAC name Tetraoxidane
Other names Hydroxyperoxide, dihydrogen tetroxide, diperoxide, bisperoxide
Identifiers
CAS Number	29683-94-1
3D model (JSmol)	Interactive image
ChemSpider	4417295
PubChem CID	5250043
InChI InChI=1S/H2O4/c1-3-4-2/h1-2H Key: RSPISYXLHRIGJD-UHFFFAOYSA-N
SMILES OOOO
Properties
Chemical formula	H2O4
Molar mass	66.012 g·mol−1
Density	1.8±0.1 g/cm3
Related compounds
Related compounds	Pentaoxidane
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Synthesis

The compound is prepared by a chemical reaction between hydroperoxyl radicals (HOO•) at low temperatures:^[5][6]

2 HOO• ⇌ H₂O₄

Physical properties

This is the fourth member of the polyoxidanes. The first three are water [(mon)oxidane], hydrogen peroxide (dioxidane), and trioxidane. Tetraoxidane is more unstable than the previous compounds. The term "tetraoxidane" extends beyond the parent compound to several daughter compounds of the general formula R
₂O
₄, where R can be hydrogen, halogen atoms, or various inorganic and organic monovalent radicals. The two Rs together can be replaced by a divalent radical, so heterocyclic tetraoxidanes also exist.^[7]

Ionization

Tetraoxidane autoionizes when in liquid form:

H₂O₄ ⇌ H⁺ + HO−4

2 H₂O₄ ⇌ H₃O+4 + HO−4