Chloropicrin

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Chloropicrin
Identifiers
CAS number 76-06-2 YesY
ChemSpider 13861343 YesY
UNII I4JTX7Z7U2 YesY
KEGG C18445 YesY
ChEBI CHEBI:39285 YesY
Jmol-3D images Image 1
Properties
Molecular formula CCl3NO2
Molar mass 164.375
Appearance colorless liquid
Density 1.692 g/ml[1]
Melting point

-69 °C

Boiling point

112 °C (dec)

Hazards
Main hazards Extremely toxic and irritating to skin, eyes, and lungs.
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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 nematicide as a stand alone treatment or in combination / co-formulation with methyl bromide and 1,3-Dichloropropene.[2][3]

Contents

[edit] 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 + 11 NaOCl → 3 Cl3CNO2 + 3 Na2CO3 + 3 NaOH + 2 NaCl

Because of the precursor he used, Stenhouse named the compound chloropicrin, although the two compounds are structurally dissimilar.

Arguably[weasel words], 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.[4] That chemical was chloropicrin. While not as lethal as other chemical weapons, it caused vomiting and was a lachrymatory agent.[4] This combination of properties forced Allied soldiers to remove their masks to vomit, exposing them to toxic gases.[4] This caused a large number of casualties on the Italian front.[4]

[edit] Preparation

Chloropicrin is manufactured by the reaction of nitromethane with sodium hypochlorite:[5]

H3CNO2 + 3 NaOCl → Cl3CNO2 + 3 NaOH

[edit] 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.[6] Tests have shown that chloropicrin causes humans to shut their eyes involuntarily.[4] Chloropicrin can be absorbed systemically through inhalation, ingestion, and the skin. It is severely irritating to the lungs, eyes, and skin.[7] Because of these properties, chloropicrin can only be delivered in shell form as a chemical weapon.[6]

[edit] Application

US Army poster from WW2.

Chloropicrin, today, is used as a fumigant to control pests found in the soil.[2] Although less common, it can be used as a poison for vertebrates, such as rabbits.[2] Chloropicrin is commonly used in combination with other fumigants, such as methyl bromide and sulfuryl fluoride, for increased potency and as a warning agent.[2]

Chloropicrin has been used in chemical warfare. It first appeared in 1917 when the Germans tested a new chemical weapon on the Italian front.[6] The new chemical weapon was devastating to the Allies at first, since they had never encountered it before.

[edit] Safety

Chloropicrin is a highly toxic chemical: NIOSH 1995 states that:

  • Chloropicrin is a lacrimator and a severe irritant of the respiratory system in humans; it also causes severe skin irritation on contact. When splashed onto the eye chloropicrin has caused corneal oedema and liquification of the cornea.
  • Exposure to concentrations of 15 ppm cannot be tolerated for more than 1 minute, and exposure to 4 ppm for a few seconds is temporarily disabling.
  • Exposure to 0.3-0.37 ppm chloropicrin for 3 to 30 seconds causes tearing and eye pain. Exposure to 15 ppm for a few seconds can cause respiratory tract injury.
  • Exposure to 119 ppm in air for 30 minutes is lethal; death is caused by pulmonary oedema.

Examples of industrial exposure in humans: 27 workers in a cellulose factory who were exposed to high levels of chloropicrin for 3 minutes developed pneumonitis after 3 to 12 hours of irritated coughing and difficulty on breathing; they subsequently developed pulmonary oedema, and one died.

EU classification of chloropicrin is: R22 Harmful if swallowed, R26 Very toxic by inhalation, R36/37/38 Irritating to eyes, skin and respiratory system, R43 May cause sensitisation by skin contact, R50/53 Very toxic to aquatic organisms, may cause long term adverse effects in the aquatic environment.

Because of chloropicrin's stability, protection requires highly effective absorbents, such as activated charcoal.[4] Chloropicrin, unlike its relative compound phosgene, is absorbed readily at any temperature, which may pose a threat in low or high temperature climates.[6]

The use of the substance has been restricted by the U.S. government, although such restriction is outdated now [8]

[edit] Portrayal in Media

In the 1987 Movie Dragnet, detectives Joe Friday (Dan Aykroyd) and Pep Streebeck (Tom Hanks) thwart an attempt by mad cultists to release a tanker truck of trichloronitromethane at a party attended by several prominent Los Angeles city officials.

The effects cited in explaining the substance (vomiting, suffocation, and death) are consistent with the actual chemical.

[edit] References

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