The common name for carbonyl chloride, COCl2, a colorless, poisonous gas made by the action of chlorine on carbon monoxide. It was used as a poison war gas. But it is now used in the manufacture of metal chlorides and anhydrides, pharmaceuticals, perfumes, isocyanate resins, and for blending in synthetic rubbers. Because of its toxicity, most phosgene is produced and employed immediately in captive applications. The biggest use of the material is for toluene diisocyanate (TDI), which is then reacted into polyurethane resins for foams, elastomers, and coatings. Polycarbonate is used for making breakresistant housings, signs, glazings, and electrical tools. Phosgene also is a reactant for the isocyanates that are used in pesticides, and the di- and polyisocyanates are adhesives, coatings, and elastomers.
Phosgene is severely irritating and corrosive to all body tissues. Irritation of the throat occurs immediately at 3 ppm, while 4 ppm causes immediate eye irritation. Exposure to 20 to 30 ppm for as little as 1 min may cause severe irritation of the upper and lower respiratory tract, with symptoms including burning throat, nausea, vomiting, chest pain, coughing, shortness of breath, and headache. Brief exposure to 50 ppm can be fatal within a few hours. Severe respiratory distress may not develop for 4 to 72 hours after exposure, at which point pulmonary edema progressing to pneumonia and cardiac failure may occur. Phosgene vapor is irritating to the eyes, and the liquid can cause severe burns to the eyes and skin. Phosgene is not regarded as a substance with adequate warning properties. Phosgene has not been found to be carcinogenic or to show reproductive or developmental toxicity in humans.
work with phosgene should be conducted in a fume hood to prevent exposure by
inhalation, and splash goggles and impermeable gloves should be worn at all times
to prevent eye and skin contact. Containers of phosgene solutions should be stored in
secondary containers, and phosgene cylinders should be stored in a cool, wellventilated
area separate from incompatible materials.
Flammability and Explosibility
When heated to decomposition or on contact with water or steam, PHOSGENE will react to produce toxic and corrosive fumes. Reacts violently with aluminum; tert-butyl azido formate; 2,4-hexadiyn-1,6-diol; isopropyl alcohol; potassium; sodium; hexafluoro isopropylidene; amino lithium; lithium. Stable in steel containers if dry. Avoid moisture.
Phosgeneisahighlypoisonousgas.Itseffectscan be treacherously dangerous, as there maynot be any immediate irritation even at lethalconcentrations. The initial symptoms aremild. However, severe congestion of lungsor pneumonia occurs 6–24 hours after exposure. The toxic symptoms include coughing, dry burning of throat, choking, chestpain, vomiting, foamy sputum (often containing blood), labored breathing, and cyanosis.Death results from anoxia. It hydrolyzes toHCl and CO2 in the lungs. A 30-minute exposure to about 100 ppm of phosgene in aircan be fatal to humans, causing death withina few hours of exposure. A concentrationof 15–20 ppm, however, exhibits only mildeffects. Chronic exposure may result in bron-chitis and fibrosis. Exposure to the gas cancause eye irritation. Contact with the liquidcan cause skin burns.
Phosgene decomposes on heating at 300°C forming chlorine and carbon monoxide:
COCl2 → Cl2 + CO
Phosgene readily reacts with water at ordinary temperatures forming hydrogen chloride and carbon dioxide:
COCl2 + H2O → 2HCl + CO2
Metal oxides decompose phosgene at elevated temperatures, forming their chlorides and carbon dioxide
COCl2 + CdO → CdCl2 + CO2
COCl2 + Fe2O3 → 2FeCl3 + 3CO2
Similar decomposition occurs when phosgene is heated with metal sulfide; the products are usually the metal chloride and carbonyl sulfide:
COCl2 + ZnS → ZnCl2 + COS
Highly poisonous gas. It manifests delayed effects. Initial symptoms may be mild, but severe congestion of lungs occurs within 6 to 24 hours after exposure. Symptoms are dry burning of the throat, choking, chest pain, vomiting, labored breathing, and cyanosis.
Phosgene is available for commercial and industrial use from various suppliers at a typical
minimum purity of99 mole percent.
Moisture, alkalis, ammonia, alcohols, copper. Reacts slowly in water to form corrosive hydrogen chloride and carbon dioxide. Violent reaction with strong oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alcohols, alkaline materials, strong acids, strong bases, alcohols, ammonia, amines, aluminum, alkali metals. Attacks many metals in presence of water. Phosgene (CG) reacts violently with strong oxidants, amines, alkalis, and many metals. Above 300C, phosgene decomposes in the presence of moisture to form hydrochloric acid and carbon dioxide. In the presence of moisture, phosgene attacks plastic, rubber, coatings and many metals.
ChEBI: An acyl chloride obtained by substitution of both hydrogens of formaldehyde by chlorine.
Phosgene was prepared first in 1812 by reacting carbon monoxide with chlorine. Phosgene was used historically as a military gas in warfare. At present, it is used extensively to make polyurethanes. These urethane polymers produce polycarbonates and chloroformates for making pesticides and pharmaceuticals.
Phosgene is an important commodity and a major industrial chemical used in the production of pesticides and plastics. As a chemical intermediate it is used in the manufacture of dyestuffs, isocyanates and their derivatives, and many other organic chemicals. It was formerly used as a war gas and is also known by itsmilitary designation as “CG.”Much of the clinical information on phosgene poisoning has been developed in the context of its military applications. It is also used in the pharmaceutical industries and in metallurgy. Of the total phosgene produced, 62% is used to manufacture toluene diisocyanate, and varying amounts are used to manufacture related chemicals.
Air & Water Reactions
Decomposes slowly in water or moist air (or when inhaled) to form very corrosive hydrogen chloride gas (hydrochloric acid) and carbon monoxide.
Phosgene, COCL2, also known as carbonyl chloride and chlorofonnyl chloride, is a colorless,poisonous gas produced by the action of chlorine and carbon monoxide. It condenses at 0 °C (32 OF) to a fuming liquid. Phosgene was used as a war gas, but is now used in the production of metal chlorides, pharmaceuticals, isocyanate resins,and perfumes.
Dry the gas with Linde 4A molecular sieves, de-gas it and distil it under vacuum at low temperature. This should be done in a closed system such as a vacuum line. It is hydrolysed by H2O but does not fume in moist air. It is available in cylinders and as a ~20% solution in toluene. It is HIGHLY TOXIC and should not be inhaled. If it is inhaled, the operator should lie still and, be made to breathe in ammonia vapour which reacts with phosgene to give urea. [Pope et al. J Chem Soc 117 1410 1920, Beilstein 3 IV 41.]
Phosgene (CG) is a colorless gas above 8.2C. Fog-like when concentrated. Colorless, fuming liquid below 8.2C. May have the appearance of a white cloud. Light yellow liquid when refrigerated or compressed. It is shipped as a liquefied compressed gas in steel cylinders. At low concentrations CG has a sweet (not pleasant) odor like newly mown hay, green corn, or moldy hay. In higher concentrations, it is poisonous with an odor that is suffocating, irritating, and pungent. The odor is only detectable for a short amount of time when CG is initially released and odor should not be regarded as a reliable indicator of overexposure. A fuming liquid below 8.3C/47F. Shipped as a liquefied compressed gas. The Odor Threshold is between 1.56 milligram per cubic meter. A choking agent, phosgene (CG) rapidly decompose in relative humidity over 70%.
PHOSGENE is a lung toxicant that causes damage to the capillaries, bronchioles and alveoli of the lungs, by decomposition to hydrochloric acid. There is little immediate irritant effect upon the respiratory tract, and the warning properties of the gas are therefore very slight. Pulmonary edema, bronchopneumonia and occasionally lung abscesses develop. Degenerative changes in the nerves have been reported as later developments. A concentration of 25 ppm is dangerous for exposures lasting 30-60 minutes and 50 ppm is rapidly fatal after even short exposure.
Phosgene is produced commercially by the reaction of CO
and chlorine gas catalyzed by activated carbon. Estimated
worldwide production exceeds 5 billion pounds. Although a
gas at atmospheric temperature and pressure, phosgene is
often supplied to industry in liquid form in pressurized steel
cylinders or in limited quantities as a solid triphosgene.
It is used in the manufacture of a variety of organic chemicals,
including dyestuffs, isocyanates, carbonic acid esters (polycarbonates),
acid chlorides, insecticides, and pharmaceuticals
(293). In metallurgy, it is used to refine ores by
chlorination of metal oxides.
Suspected sources of atmospheric phosgene are fugitive
emissions. Phosgene can be generated by thermal decomposition
of chlorinated hydrocarbons (including carbon tetrachloride,
methylene chloride, trichloroethylene, or butyl
chloroformate) and photooxidation of chloroethylenes in
the ambient air. Occupational exposures have resulted
from heating paint removers, degreasers, and welding on
freshly degreased parts. Phosgene levels have
been measured in ambient air with an ambient concentration
median of 80 ng/m3. Chlorinated hydrocarbons,
such as chloroform, can also degrade spontaneously. One
example involved laboratory personnel who became ill when
working with 3-year-old chloroform. Subsequent analysis
found 15,000 ppm phosgene in the headspace of the bottle
and a 1.1% phosgene concentration in the bulk solution
(299, 300). Decomposition of chlorinated hydrocarbons
can produce other toxic chemicals, including hydrogen
chloride, chlorine, and dichloroacetyl chloride.
UN1076 Phosgene, Hazard Class: 2.3; Labels: 2.3-Poisonous gas, 8-Corrosive material, Inhalation, Hazard Zone A. Cylinders must be transported in a secure upright position, in a well-ventilated truck. Protect cylinder and labels from physical damage. The owner of the compressed gas cylinder is the only entity allowed by federal law (49CFR) to transport and refill them. It is a violation of transportation regulations to refill compressed gas cylinders without the express written permission of the owner. Military driver shall be given full and complete information regarding shipment and conditions in case of emergency.AR 50-6 deals specifically with the shipment of chemical agents. Shipments of agent will be escorted in accordance with AR 740-32
PHOSGENE is an intermediate in organic synthesis, especially production of toluene diisocyanate and polymethylene polyphenylisocyanate; in metallurgy to separate ores by chlorination of the oxides and volatilization; occurs as a product of combustion whenever a volatile chlorine compound comes in contact with a flame or very hot metal; originally manufactured as an agent for chemical warfare during World War I.
COCl2 is a very poisonous gas that was used in combat in the early twentieth
century. When not concentrated, it smells like newly cut hay or grass.
Principles and methods for destruction of chemical weapons: “Destruction of chemical weapons” means a process by which chemicals are converted in an essentially irreversible way to a form unsuitable for production of chemical weapons, and which in an irreversible manner renders munitions and other devices unusable as such. Each nation shall determine how it shall destroy chemical weapons, except that the following processes may not be used: dumping in any body of water, land burial or open-pit burning. It shall destroy chemical weapons only at specifically designated and appropriately designed and equipped facilities. Each nation shall ensure that its chemical weapons destruction facilities are constructed and operated in a manner to ensure the destruction of the chemical weapons; and that the destruction process can be verified under the provisions of this Convention (Organization for the Prohibition of Chemical Weapons; Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and Their Destruction). Return refillable compressed gas cylinders to supplier. Phosgene may be neutralized by covering it with sodium bicarbonate or an equal mixture of soda ash and slaked lime. After mixing, spray carefully with water. Transfer slowly to a larger container of water. Do not use water directly on spill. Pass controlled discharges of phosgene through 10% NaOH solution in a scrubbing tower . Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal.
Phosgene can be deadly at a concentration as low as 2 ppm. Phosgene is used as an intermediate in the manufacture of many industrial chemicals, including dyes and plastics; in the making of dyestuffs based on triphenylmethane, coal tar, and urea. It is also used in the organic synthesis of isocyanates and their derivatives, carbonic acid esters (polycarbonates); and acid chlorides. Other applications include its utilization in metallurgy; and in the manufacture of some insecticides and pharmaceuticals. Exposure to phosgene may occur during arc welding and in fires involving vinyl chloride; released from household paint removers and degreasers when they are used in the presence of heat. Phosgene (CG) has been used as a military choking, pulmonary agent since WW I, and has become a staple of chemical arsenals in many countries
Phosgene is a strong lung irritant and also attacks other parts of the respiratory system. Low
concentrations in air cause watering of the eyes
and coughing, which may result in a thin, frothy
expectoration. It will also result in upper respiratory tract irritation and bronchitis. High concentrations cause greater distress such as shortness of breath, choking, coughing, chest tightness, and painful breathing.
ACGIH recommends a Threshold Limit
Value-Time-Weighted Average (TLV-TWA)
of 0.1 ppm (0.40 mg/m3) for phosgene. The
TLV- TWA is the time-weighted average concentration for a normal 8-hour workday and a
40-hour workweek, to which nearly all workers
may be repeatedly exposed, day after day, without adverse effect. In addition, ACGIH recommends a Threshold Limit Value-Ceiling (TLVq of 0.1 ppm (0.4 mg/m3) for phosgene. The
TLV-C is the concentration that should not be
exceeded during any part of the working exposure.
One serious difficulty with the treatment of
persons exposed to phosgene is that more serious symptoms may not appear until 2 to 24
hours after the exposure. These include bloody
sputum, increasing shortness of breath, pulmonary edema, and respiratory failure. The delayed action of phosgene can be particularly
injurious if the victim performs heavy exercise
after having been exposed. Persistent effects
after acute lung injury from phosgene can include bronchiolitis obliterans.
Phosgene is hydrolyzed to hydrogen chloride
and chlorine in the alveoli ofthe lungs, which in
turn causes irritation and results in pulmonary
edema and subsequently leads to respiratory and
All persons who have been exposed to phosgene must be examined by a physician as soon
as possible because serious symptoms may develop subsequently.
PHOSGENE is water reactive. Incompatible with strong oxidizing agents, alcohols, amines, alkali. May react violently with aluminum, alkali metals (lithium, potassium, sodium), alcohols (isopropyl alcohol, 2,4-hexadiyn-1,6-diol), sodium azide [Bretherick, 5th ed., 1995, p. 134]. May react vigorously or explosively if mixed with diisopropyl ether or other ethers in the presence of trace amounts of metal salts [J. Haz. Mat., 1981, 4, 291]. PHOSGENE reacts with phosphate or silicate salts, yielding water-reactive and toxic POCl3 with phosphates (Dunlap, K.L. 2005. PHOSGENE. In Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley & Sons, Inc.).
Phosgene is manufactured in many facilities in the United States and in many other countries. Typical production processes involve the reaction of carbon monoxide with nitrosyl chloride, or the reaction of carbon tetrachloride with oleum.
Phosgene is used mainly as an intermediate in the manufacture of many types of compounds, including barbiturates; chloroformates and thiochloroforrnates; carbamoyl chlorides, acid chlorides, and acid anhydrides; carbamates; carbonates and pyrocarbonates; urethanes; ureas; azo-urea dyes, triphenylmethane dyes, and substituted benzophenones; isocyanates and isothiocyanates; carbazates and carbohydrazides; malonates; carbodimides; and oxazolidinedions. It is also used in bleaching sand for glass manufacture and as a chlorinating agent.
A human poison by inhalation, A severe eye, skin, and mucous membrane irritant. In the presence of moisture, phosgene decomposes to form hydrochloric acid and carbon monoxide. This occurs in the bronchioles and alveoli of the lungs, resulting in pulmonary edema followed by bronchopneumonia and occasionally lung abscess. There is little immediate irritating effect upon the respiratory tract, and the warning properties of the gas are therefore very slight. There may be no immedate warning that dangerous concentrations are being inhaled. After a latent period of 2 to 24 hours, the patient complains of burning in the throat and chest, shortness of breath, and increasing dyspnea. Where the exposure has been severe, the development of pulmonary edema may be so rapid that the patient dies within 36 hours after exposure. In cases where the exposure has been less, pneumonia may develop several days after the occurrence of the accident. In patients who recover, no permanent residual disability is thought to occur. A common air contaminant. Under the appropriate conditions it undergoes hazardous reactions with Al, tertbutyl azido formate, 2,4-hexadiyn-l,6-diol, isopropyl alcohol, K, Na, sodium azide, hexafluoroisopropylideneamino lithium, lithium. When heated to decomposition or on contact with water or steam it will react to produce toxic and corrosive fumes of CO and Cl-. Caution: Arrangements should be made for monitoring its use
Phosgene is prepared by the reaction of carbon monoxide and chlorine. The mixture of these gases is passed over activated carbon:
CO + Cl2 → COCl2
Alternatively, phosgene can be made by reacting carbon monoxide with nitrosyl chloride, or by treating carbon tetrachloride with oleum.
Colorless gas; density 4.34 g/L; heavier than air, density in air 3.41 (air=1); liquefies at 8.3°C; liquid density 1.432 g/mL; freezes at –118°C; slightly soluble in water with slow decomposition; also decomposed by alcohol and acids; soluble in benzene, toluene and acetic acid; critical temperature 182°C; critical pressure 56.04 atm; critical volume 190 cm3/mol.
Colorless gas at ambient temperature; strong, pungent odor; density of the gas 4.045 g/L at 25°C; density of the liquid 1.392 g/mL at 4°C; liquefies to a light yellow fluid at 8.2°C; freezes at -128°C; critical temperature 182°C, critical pressure 55.96 atm, critical volume 190 cm3/mol; slightly soluble in water with slow hydrolysis; soluble in benzene, toluene and acetic acid.
Anhydrous phosgene in the liquid state is compatible with a variety of common metals, including aluminum (of 99.5 percent purity), copper, pure iron or cast iron, steel (including cast
steel and chrome-nickel steels), lead (up to
250°F or 121°q, nickel, and silver; it is also
compatible with platinum and platinum alloys in
instruments. Nonmetallic materials with which
liquid anhydrous phosgene is also compatible
include acid resistant linings (ceramic plates and
carbon blocks), enamel on cast iron or
glass-lined steel, Pyrex or Kimax, porcelain,
quartzware, granite or basalt natural stone,
stoneware, and Teflon.
In the presence of moisture, phosgene is not
compatible with copper, steel, or pure or cast
iron. Detailed data on the corrosion resistance
of various materials to phosgene under a range
of conditions are given in Corrosion Data Survey-Metals Section of the National Association
For commercial (nonlaboratory) applications,
steel piping with seamless fittings is recommended for handling phosgene, and pipe no
smaller than 4-inch (l0.2-cm) nominal size
should be used to ensure rigidity and minimize
possible leaks. For pipe size up to 4 inches
(10.2 cm), Schedule 80 seamless (or alloy steel
to ASTM A333 GR3) piping is recommended;
6-inch (15.2-cm) diameter Schedule 40 seamless may be used as a larger pipe size.
Screwed or flanged joints should be kept to a
minimum, and cast iron or malleable iron fittings and valves should not be used; nonarmored porcelain valves must not be used, regardless of the pressure with either liquid or
gaseous phosgene. Only outside yoke or rising stem valves are recommended to reduce the
possibility of accident; nonindicating valves
should not be used. Monel is the material generally used in manually operated valves for the
disk, seat, and stem components.
A pipe joint compound of Teflon-based type
dope is usually used. Detailed recommendations
on these and other materials for various purposes in phosgene service may be obtained from
Phosgene is a colourless, reactive, non-flammable gas that is heavier than air with a musty
hay odour. Phosgene is commonly stored under high pressure as a liquid. Phosgene
reacts with water to form corrosive acids, reacts with most metals in the presence of
moisture, liberating hydrogen, an extremely flammable gas, and reacts violently with
alkalis. As an industrial and commercially important chemical, phosgene is a precursor
material/chemical intermediate, and has extensive application in the manufacture
of a wide range of products such as polymers – polyurethanes and polycarbonates –
pesticides, medicines, dyestuffs, some insecticides, pharmaceuticals, and in metallurgy.