7335. Phosgene

Nomenclature

CAS number: 75-44-5
Carbonic dichloride; carbonyl chloride; chloroformyl chloride.
CCl2O; mol wt 98.92.
C 12.14%, Cl 71.68%, O 16.17%.
Cl2C=O.

Description and references

Prepn from chlorine + carbon monoxide: Whitehouse, US 1231226 (1917); Peacock, US 1360312 (1921); Bradner, US 1457493 (1923); Douthitt, US 2847470 (1958 to Texas Co.); from carbon monoxide + nitrosyl chloride: Williams, US 1746506 (1930 to du Pont Ammonia Corp.); from carbon tetrachloride + oleum: Murphy, Reuter, Aust. Chem. Inst. J. Proc. 15, 144 (1948). Toxicology: S. A. Cucinell, Arch. Environ. Health 28, 272 (1974). Review: E. E. Hardy in Kirk-Othmer Encyclopedia of Chemical Technology vol. 17 (Wiley-Interscience, New York, 3rd ed., 1982) pp 416-425.

Properties

Colorless, highly toxic gas; suffocating odor; when much diluted with air there is an odor reminiscent of moldy hay. Condenses at ≈0° to a clear, colorless, fuming liquid. d40 1.432. mp -118°. bp760 8.2°. Vapor press at 20°: 1215 mm. Poisonous; corrosive; spontaneously combustible. Slightly sol in water and slowly hydrolyzed by it; freely sol in benzene, toluene, glacial acetic acid and most liquid hydrocarbons.

Caution

Severe pulmonary irritant, although not immediately irritating even in potentially lethal exposures. Potential symptoms of overexposure by inhalation may initially be mild and transient and include burning of eyes, cough, dry burning throat, dyspnea, foamy sputum, chest pain, vomiting. Delayed symptoms include peribronchial edema, pulmonary congestion, alveolar edema, cyanosis, anoxia. Direct contact with liquid may cause frostbite. See Clinical Toxicology of Commercial Products, R. E. Gosselin et al., Eds. (Williams & Wilkins, Baltimore, 5th ed., 1984) Section II, p 96; NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH, 97-140, 1997) p 252; Patty's Industrial Hygiene and Toxicology vol. 2F, G. D. Clayton, F. E. Clayton, Eds. (Wiley-Interscience, New York, 4th ed., 1994) pp 4557-4563.

Note

Paper soaked in alcoholic or carbon tetrachloride soln contg 10% of a mixture of equal parts of p-dimethylaminobenzaldehyde and colorless diphenylamine, then dried, will turn from yellow to deep orange in the presence of approx the max allowable concn of phosgene, and should always be used where the generation of this gas is possible or suspected.

Use

For the prepn of many organic chemicals; as a war gas.