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Phosgene gas

Phosgene
Full structural formula with dimensions
Space-filling model
Names
Preferred IUPAC name
Carbonyl dichloride
Other names
CG
Carbon dichloride oxide
Carbon oxychloride
Chloroformyl chloride
Dichloroformaldehyde
Dichloromethanone
Dichloromethanal
Identifiers
75-44-5 YesY
3D model (Jmol) Interactive image
ChEBI CHEBI:29365 YesY
ChemSpider 6131 YesY
ECHA InfoCard 100.000.792
EC Number 200-870-3
PubChem 6371
RTECS number SY5600000
UNII 117K140075 YesY
UN number 1076
Properties
COCl2
Molar mass 98.92 g/mol
Appearance colorless gas
Odor suffocating, like musty hay
Density 4.248 g/L (15 °C, gas)
1.432 g/cm3 (0 °C, liquid)
Melting point −118 °C (−180 °F; 155 K)
Boiling point 8.3 °C (46.9 °F; 281.4 K)
decomposes in water
Solubility soluble in benzene, toluene, acetic acid
decomposes in alcohol and acid
Vapor pressure 1.6 atm (20°C)
−48·10−6 cm3/mol
Structure
Planar, trigonal
1.17 D
Hazards
Safety data sheet ICSC 0007
Very Toxic T+
R-phrases R26 R34
S-phrases (S1/2) S9 S26 S36/37/39 S45
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 4: Very short exposure could cause death or major residual injury. E.g., VX gas Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point Non-flammable
0.1 ppm
Lethal dose or concentration (LD, LC):
500 ppm (human, 1 min)
340 ppm (rat, 30 min)
438 ppm (mouse, 30 min)
243 ppm (rabbit, 30 min)
316 ppm (guinea pig, 30 min)
1022 ppm (dog, 20 min)
145 ppm (monkey, 1 min)
3 ppm (human, 2.83 h)
30 ppm (human, 17 min)
50 ppm (mammal, 5 min)
88 ppm (human, 30 min)
46 ppm (cat, 15 min)
50 ppm (human, 5 min)
2.7 ppm (mammal, 30 min)
US health exposure limits (NIOSH):
PEL (Permissible)
TWA 0.1 ppm (0.4 mg/m3)
REL (Recommended)
TWA 0.1 ppm (0.4 mg/m3) C 0.2 ppm (0.8 mg/m3) [15-minute]
IDLH (Immediate danger)
2 ppm
Related compounds
Related compounds
Thiophosgene
Formaldehyde
Carbonic acid
Urea
Carbon monoxide
Chloroformic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY  (what is YesYN ?)
Infobox references

Phosgene is the chemical compound with the formula COCl2. This colorless gas gained infamy as a chemical weapon during World War I where it was responsible for about 85% of the 100,000 deaths caused by chemical weapons. It is also a valued industrial reagent and building block in synthesis of pharmaceuticals and other organic compounds. In low concentrations, its odor resembles freshly cut hay or grass. In addition to its industrial production, small amounts occur from the breakdown and the combustion of organochlorine compounds, such as those used in refrigeration systems. The chemical was named by combining the Greek words "phos" (meaning light) and "genesis" (birth); it does not mean it contains any phosphorus (cf. phosphine).

Phosgene is a planar molecule as predicted by VSEPR theory. The C=O distance is 1.18 Å, the C−Cl distance is 1.74 Å and the Cl−C−Cl angle is 111.8°. It is one of the simplest acid chlorides, being formally derived from carbonic acid.

Industrially, phosgene is produced by passing purified carbon monoxide and chlorine gas through a bed of porous activated carbon, which serves as a catalyst:

The reaction is exothermic, therefore the reactor must be cooled. Typically, the reaction is conducted between 50 and 150 °C. Above 200 °C, phosgene reverts to carbon monoxide and chlorine, Keq(300 K) = 0.05. World production of this compound was estimated to be 2.74 million tonnes in 1989.


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