Title: Chlorine Monoxide
CAS Registry Number: 7791-21-1
Additional Names: Dichlorine monoxide; dichloromonoxide; dichloroxide; hypochlorous anhydride
Molecular Formula: Cl2O
Molecular Weight: 86.91
Percent Composition: Cl 81.59%, O 18.41%
Literature 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°.
Melting point: mp -120.6°
Boiling point: bp 2.2°
CAUTION: Intensely irritating to eyes, skin, mucous membranes, respiratory tract.
Use: Chlorinating agent.