2099. Chlorine Monoxide

Nomenclature

CAS number: 7791-21-1
Dichlorine monoxide; dichloromonoxide; dichloroxide; hypochlorous anhydride.
Cl2O; mol wt 86.91.
Cl 81.59%, O 18.41%.

Description and references

First preparation by J. L. Gay-Lussac in 1842 from yellow mercuric oxide and chlorine. See also: Cady, Inorg. Synth. 5, 156 (1957); Schmeisser in Handbook of Preparative Inorganic Chemistry vol. 1, G. Brauer, Ed. (Academic Press, New York, 2nd ed., 1963) p 299. Use as a powerful and selective chlorinating agent: F. D. Marsh et al., J. Am. Chem. Soc. 104, 4680 (1982).

Properties

Yellowish-brown gas. Disagreeable, penetrating odor. Explodes on contact with organic matter. Can also be caused to explode by a spark or by heating. Dec at moderate rate at room temp. mp -120.6°. bp 2.2°. Trouton constant: 22.5. Suffers photochemical and thermal decompn: at 100-140° there is an induction period, followed by a second order reaction, see N. V. Sidgwick, The Chemical Elements and Their Compounds vol. II (Oxford, 1950) p 1201. One vol of water at 0° dissolves more than 100 vols Cl2O with formation of HClO; sol in CCl4. Stored as a liquid or solid at temps below -80°.

Caution

Intensely irritating to eyes, skin, mucous membranes, respiratory tract.

Use

Chlorinating agent.