Chlorine peroxide (also known as dichlorine dioxide or ClO dimer) is a molecular compound with formula ClOOCl.
Chemically, it is a
dimer of the
chlorine monoxide
Chlorine monoxide is a chemical radical with the chemical formula ClO•. It plays an important role in the process of ozone depletion. In the stratosphere, chlorine atoms react with ozone molecules to form chlorine monoxide and oxygen.
:Cl• ...
radical (ClO·). It is important in the formation of the
ozone hole
Ozone depletion consists of two related events observed since the late 1970s: a lowered total amount of ozone in Earth, Earth's upper atmosphere, and a much larger springtime decrease in stratospheric ozone (the ozone layer) around Earth's polar ...
.
Chlorine peroxide catalytically converts ozone into oxygen when it is irradiated by ultraviolet light.
Production
Chlorine peroxide can be produced by laser or ultraviolet
photolysis
Photodissociation, photolysis, photodecomposition, or photofragmentation is a chemical reaction in which molecules of a chemical compound are broken down by absorption of light or photons. It is defined as the interaction of one or more photons wi ...
of the chlorine molecule with ozone.
The lasers used to break up the chlorine molecule into atoms can be an
excimer laser
An excimer laser, sometimes more correctly called an exciplex laser, is a form of ultraviolet laser which is commonly used in the production of microelectronic devices, semiconductor based integrated circuits or "chips", eye surgery, and micro ...
at 248, 308, or 352 nm wavelength.
(CF
2Cl
2) can also act as a source of chlorine atoms for the formation of the peroxide.
Microwave discharge can also break up chlorine molecules into atoms that react with ozone to make chlorine peroxide.
:Cl
2 + ''h''ν
→ 2Cl
:Cl + O
3 → O
2 + ClO·
:2ClO· + M
→ ClOOCl + M
:ClOOCl + ''h''ν
→ Cl + ClO
2
:ClO
2 + M
→ Cl + O
2 + M
Properties
Chlorine peroxide absorbs ultraviolet light with a maximum absorbing wavelength of 245 nm. It also absorbs longer wavelengths up to 350 nm to a lesser extent. This is important as ozone absorbs up to 300 nm.
The Cl−O bond length is 1.704 Å, and the O−O bond is 1.426 Å long.
The ClOO bond angle is 110.1°, and the
dihedral angle between the two Cl−O−O planes is 81°
References
{{Chlorine compounds
Peroxides
Chlorine oxides