|Phosgene is the chemical compound with the formula COCl2. It is a colorless gas which gained importance as a chemical weapon during World War I.Phosgene was synthesized by the British chemist John Davy in 1812 by exposing a mixture of carbon monoxide and chlorine to sunlight.
In low concentrations, its odor resembles freshly cut hay or grass.
|It is also an industrial reagent in synthesis of pharmaceuticals and other organic compounds. In addition to its industrial production, small amounts occur naturally from the breakdown and the combustion of organochlorine compounds, such as those used in refrigeration systems.Phosgene is produced by passing purified carbon monoxide and chlorine gas through a bed of porous activated carbon, which serves as a catalyst.
Upon ultraviolet (UV) radiation in the presence of oxygen, chloroform slowly converts into phosgene. To suppress this photodegradation, chloroform is often stored in brown-tinted glass containers.
The great majority of phosgene is used in the production of isocyanates, The isocyanates are precursors to polyurethanes.
Significant amounts are also used in the production of polycarbonates. Polycarbonates are an important class of engineering thermoplastic found, for example, in lenses in eye glasses.
|Phosgene is an insidious poison as the odor may not be noticed and symptoms may be slow to appear. Its high toxicity arises from the action of the phosgene on the proteins in the pulmonary alveoli, which are the site of gas exchange. The damage to the alveoli disrupts the blood-air barrier, causing suffocation.Sodium bicarbonate may be used to neutralise liquid spills of phosgene. Gaseous spills may be neutraised with ammonia.|
|Following the extensive use of phosgene gas in combat during World War I, it was stockpiled by various countries as part of their secret chemical weapons programs.Phosgene was frequently used by the Imperial Japanese Army against the Chinese during the Second Sino-Japanese War.|
|Chlorine was Discovered in 1774 by Carl Wilhelm Scheele.Chlorine gas is two and one half times as heavy asair, has an intensely disagreeable suffocating odor, and is exceedingly poisonous. In its liquid and solid form it is a powerful oxidizing, bleaching, and disinfecting agent.In nature it is only found combined with other elements chiefly sodium in the form of common salt – NaClIt is an essential microutrient for higher plants. Growth suffers if the amount of chloride in the soil fall below 2 ppm.|
|Chlorine is an important chemical in water purification. Chlorine is also used widely in the manufacture of many products and items directly or indirectly:
|Exposure to chlorine can occur in the workplace. People who use laundry bleach and swimming pool chemicals containing chlorine products are usually not exposed to chlorine itself. Chlorine is generally found only in industrial settings.Chlorine enters the body breathed in with contaminated air or when consumed with contaminated food or water. It does not remain in the body, due to its reactivity.Effects of chlorine on human health depend on how the amount of chlorine that is present, and the length and frequency of exposure. Effects also depend on the health of a person or condition of the environment when exposure occurs.Breathing small amounts of chlorine for short periods of time adversely affects the human respiratory system. Effects differ from coughing and chest pain, to water retention in the lungs. Chlorine irritates the skin, the eyes, and the respiratory system. These effects are not likely to occur at levels of chlorine that are normally found in the environment.|
As a Chemical Weapon
The German Army first used chlorine gas cylinders in April 1915 against the French Army at Ypres. French soldiers reported seeing yellow-green clouds drifting slowly towards the Allied trenches. They also noticed its distinctive smell which was like a mixture of pineapple and pepper. At first the French officers assumed that the German infantry were advancing behind a smoke screen and orders were given to prepare for an armed attack. When the gas arrived at the Allied front-trenches soldiers began to complain about pains in the chests and a burning sensation in their throats.
Chlorine gas destroyed the respiratory organs of its victims and this led to a slow death by asphyxiation.
|VX is O-ethyl S-diisopropylaminomethyl methylphosphonothiolateIt is a brownish liquid substance and its vapours are odourless. The United States began producing it in April 1961, but its composition was not known for another decade. VX is among the most toxic substances known. Mere droplets can kill. It can remain on material and, equipment and terrain for long periods. Uptake is mainly through the skin but also through inhalation of the substance as a gas or aerosol.|
|It was invented by a German chemist, Gerhard Schrader, in the mid 1930s.It is a colourless or brownish as a liquid and odorless as a vapor. Schrader worked for IG Farben, a company that later used slave labour from the Birkenau concentration camp to produce its products. Another one of Fraben’s invention was Zyklon-B, a type of hydrogen cyanide used by the Nazis to gas victims in those same camps during World War II. Tabun is also an organophosphate like many pesticides and is among the easiest to nerve gases to manufacture.|