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Chloropicrin
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Chloropicrin, also known as "PS", is a chemical compound with the structural formula Cl3CNO2. This colourless highly toxic liquid was once used in chemical warfare and is currently used as a fumigant and nematocide.
ropicrin was first discovered in 1848 by a Scottish chemist John Stenhouse. He prepared it by the reaction of a chlorinating agent with picric acid:
- HOC6H2(NO2)3 + 10 NaOCl ? 3 Cl3CNO2 + 3 NaOH + NaCl + 3 CO2
Because of the precursor he used, Stenhouse named the compound chloropicrin, although the two compounds are structurally dissimilar.
Arguably, chloropicrin's most famous use was in World War I.
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Encyclopedia
Chloropicrin, also known as "PS", is a chemical compound with the structural formula Cl3CNO2. This colourless highly toxic liquid was once used in chemical warfare and is currently used as a fumigant and nematocide.
History
Chloropicrin was first discovered in 1848 by a Scottish chemist John Stenhouse. He prepared it by the reaction of a chlorinating agent with picric acid:
- HOC6H2(NO2)3 + 10 NaOCl ? 3 Cl3CNO2 + 3 NaOH + NaCl + 3 CO2
Because of the precursor he used, Stenhouse named the compound chloropicrin, although the two compounds are structurally dissimilar.
Arguably, chloropicrin's most famous use was in World War I. In 1917, there were reports that the Germans were testing and using a new chemical in warfare. That chemical was chloropicrin. While not as lethal as other chemical weapons, it caused vomiting and was a lachrymatory agent. This combination of properties forced allied soldiers to remove their masks to vomit, exposing them to toxic gases. This cause a large amount of casualties on the Italian front.
Preparation
Chloropicrin is manufactured by the reaction of nitromethane with sodium hypochlorite:
- H3CNO2 + 3 NaOCl ? Cl3CNO2 + 3 NaOH
Properties
As listed in the Table, chloropicrin is a colorless liquid that is insoluble in water, with which it is stable. With a vapor pressure of 24 mm Hg, its volatility is between that of phosgene and mustard gas in persistency, although closer to phosgene because it is related to the compound. Tests have shown that chloropicrin causes humans to shut their eye shuts involuntary. Chloropicrin can be absorbed systemically through inhalation, ingestion, and the skin. It is severely irritating to the lungs, eyes, and skin. Because of these properties, chloropicrin can only be delivered in shell form as a chemical weapon.
Application
Chloropicrin, today, is used as a fumigant to control pests found in the soil. Although less common it can be used as a poison for vertebrates, such as rabbits. Chloropicrin is commonly used in combination with other fumigants, such as methyl bromide, for increased potency and as a warning agent.
Chloropicrin has been used in chemical warfare. It first appeared in 1917 when the Germans tested a new chemical weapon on the Italian front. The new chemical weapon was devastating to the Allies at first, since they had never encountered it before.
Safety
Chloropicrin is a highly dangerous and toxic chemical. At concentrations above 1.1 ppm, chloropicrin irritates the eyes; between 1 to 3ppm can also cause excessive crying. Above 4ppm will limit a person's ability to participate in work or activity. A one minute exposure to chloropicrin above 15ppm can cause respiratory damage.
Because of chloropicrin's stability, protection requires highly effective absorbents, such as activated charcoal. Chloropicrin, unlike it's relative compound phosgene, is absorbed readily at any temperature, which may pose a threat in low or high temperature climates.
See also
- Use of poison gas in World War I.
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