Chlorine monoxide

From Wikipedia, the free encyclopedia
Jump to: navigation, search
This article is about the compound ClO. For the oxoanion with the formula ClO
, see hypochlorite. For the molecule Cl2O, see Dichlorine monoxide.
Chlorine monoxide
Chlorosyl.svg Chlorine-monoxide-3D-vdW.png
Abbreviations ClO(.)
CAS number 12301-79-0
PubChem 166686 YesY
ChemSpider 145843 YesY
MeSH Chlorosyl
Jmol-3D images Image 1
Molecular formula ClO
Molar mass 51.45 g mol−1
101.8 kJ/mol[1]
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Chlorine monoxide is a chemical radical with the 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· + O
→ ClO· + O

This reaction causes the depletion of the ozone layer.[1] This reaction can go on and the ClO· radicals can go on to react as such:

ClO· + O· → Cl· + O

regenerating the chlorine radical. In this way, the overall reaction for the decomposition of ozone is catalyzed by chlorine, as ultimately chlorine remains unchanged. The overall reaction is:

O· + O
→ + 2O

This has been a significant impact of the use of CFCs on the upper stratosphere. The nonreactive nature of CFC's allows them to pass into the stratosphere, where they undergo photo-dissociation to form Cl radicals. These then readily form chlorine monoxide, and this cycle can continue until two radicals react to form dichlorine dioxide, terminating the radical reaction. Because the concentration of CFCs in atmosphere is very low, the probability of a terminating reaction is exceedingly low, meaning each radical can decompose many thousands of molecules of ozone.


  1. ^ a b Egon Wiberg; Nils Wiberg; Arnold Frederick Holleman (2001). Inorganic chemistry. Academic Press. p. 462. ISBN 0-12-352651-5.