| |||
| Names | |||
|---|---|---|---|
| IUPAC name Trichloro(nitro)methane | |||
Other names
| |||
| Identifiers | |||
| |||
3D model (JSmol) | |||
| 1756135 | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
| ||
| ECHA InfoCard | 100.000.847 | ||
| EC Number |
| ||
| 240197 | |||
| KEGG |
| ||
| RTECS number |
| ||
| UNII | |||
| UN number | 1580 | ||
| |||
| |||
| Properties | |||
| CCl3NO2 | |||
| Molar mass | 164.375 g/mol | ||
| Appearance | colorless liquid | ||
| Odor | irritating[1] | ||
| Density | 1.692 g/ml | ||
| Melting point | −69 °C (−92 °F; 204 K) | ||
| Boiling point | 112 °C (234 °F; 385 K) (decomposes) | ||
| 0.2%[1] | |||
| Vapor pressure | 18 mmHg (20°C)[1] | ||
| −75.3·10−6 cm3/mol | |||
| Hazards | |||
| Occupational safety and health (OHS/OSH): | |||
Main hazards | Extremely toxic and irritating to skin, eyes, and lungs. | ||
| GHS labelling: | |||
    | |||
| Danger | |||
| H301,H314,H330,H370,H372,H410 | |||
| P260,P264,P270,P271,P273,P280,P284,P301+P310,P301+P330+P331,P303+P361+P353,P304+P340,P305+P351+P338,P307+P311,P310,P314,P320,P321,P330,P363,P391,P403+P233,P405,P501 | |||
| NFPA 704 (fire diamond) | |||
| Lethal dose or concentration (LD, LC): | |||
LC50 (median concentration) | 9.7 ppm (mouse, 4 hr) 117 ppm (rat, 20 min) 14.4 ppm (rat, 4 hr)[2] | ||
LCLo (lowest published) | 293 ppm (human, 10 min) 340 ppm (mouse, 1 min) 117 ppm (cat, 20 min)[2] | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible) | TWA 0.1 ppm (0.7 mg/m3)[1] | ||
REL (Recommended) | TWA 0.1 ppm (0.7 mg/m3)[1] | ||
IDLH (Immediate danger) | 2 ppm[1] | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Chloropicrin, also known asPS (fromPort Sunlight[3]) andnitrochloroform, is a chemical compound currently used as a broad-spectrum antimicrobial, fungicide,herbicide,insecticide, andnematicide.[4] It was used as apoison gas in World War I and the Russian military has been accused of using it in theRusso-Ukrainian War.[5][6][7] Its chemical structural formula isCl3C−NO2.
Chloropicrin was discovered in 1848 by Scottish chemistJohn Stenhouse. He prepared it by the reaction ofsodium hypochlorite withpicric acid:
Because of the precursor used, Stenhouse named the compound chloropicrin, although the two compounds are structurally dissimilar.
Today, chloropicrin is manufactured by the reaction ofnitromethane withsodium hypochlorite:[8]
Reaction ofchloroform andnitric acid also yields chloropicrin:[9]
Chloropicrin's chemical formula isCCl3NO2 and its molecular weight is 164.38 grams/mole.[10] Pure chloropicrin is a colorless liquid, with a boiling point of 112 °C.[10] Chloropicrin is sparingly soluble in water with solubility of 2 g/L at 25 °C.[10] It is volatile, with a vapor pressure of 23.2millimeters of mercury (mmHg) at 25 °C; the correspondingHenry's law constant is 0.00251 atmosphere-cubic meter per mole.[10] Theoctanol-water partition coefficient (Kow) of chloropicrin is estimated to be 269.[10] Its soil adsorption coefficient (Koc; normalized to soil organic matter content) is 25 cm3/g.[10]
Chloropicrin was manufactured for use aspoison gas in World War I.[11] InWorld War I, German forces used concentrated chloropicrin against Allied forces as atear gas. While not as lethal as other chemical weapons, it inducedvomiting and forced Allied soldiers to remove their masks to vomit, exposing them to more toxic gases used as weapons during the war.[12] It was also used by theImperial Russian Army in hand grenades as 50% solution insulfuryl chloride.[13]
In February 2024,Ukrainian GeneralOleksandr Tarnavskyi accused theRussian Armed Forces of using chloropicrinmunitions.[14] In May 2024, theUnited States Department of State also alleged use of chloropicrin by Russian forces in Ukraine, and imposed sanctions against Russian individuals and entities as a response.[15] Dutch and German intelligence agencies found chloropicrin use to be "commonplace" by July 2025.[16]
In agriculture, chloropicrin is injected into soil prior to planting a crop tofumigate soil. Chloropicrin affects a broad spectrum offungi,microbes andinsects.[17] It is commonly used as a stand-alone treatment or in combination / co-formulation withmethyl bromide and1,3-dichloropropene.[17][18] Chloropicrin is used as an indicator and repellent when fumigating residences for insects withsulfuryl fluoride which is an odorless gas.[citation needed] Chloropicrin'smode of action is unknown[19] (IRAC MoA 8B).[20] Chloropicrin may stimulateweedgermination, which can be useful when quickly followed by a more effectiveherbicide.[21]
Chloropicrin was first registered in 1975 in the US. After a 2008 re-approval, theEPA[22] stated that chloropicrin "means more fresh fruits and vegetables can be cheaply produced domestically year-round because several severe pest problems can be efficiently controlled."[23][24] To ensure chloropicrin is used safely, the EPA requires a strict set of protections for handlers, workers, and persons living and working in and around farmland during treatments.[25][24] EPA protections were increased in both 2011 and 2012, reducingfumigant exposures and significantly improving safety.[26] Protections include the training of certified applicators supervising pesticide application, the use of buffer zones, posting before and during pesticide application, fumigant management plans, and compliance assistance and assurance measures.[citation needed]
Used as a preplant soil treatment measure, chloropicrin suppresses soilborne pathogenicfungi and somenematodes andinsects. According to chloropicrin manufacturers, with ahalf-life of hours to days, it is completely digested by soil organisms before the crop is planted, making it safe and efficient.[citation needed] Contrary to popular belief, chloropicrin does notsterilize soil and does notdeplete the ozone layer, as the compound is destroyed by sunlight. Additionally, chloropicrin has never been found ingroundwater, due to its low solubility.[27]
InCalifornia, experience with acute effects of chloropicrin when used as a soil fumigant forstrawberries and othercrops led to the release of regulations in January 2015 creating buffer zones and other precautions to minimize exposure to farm workers, neighbors, and passersby.[28][29]
At a national level, chloropicrin is regulated in theUnited States by theUnited States Environmental Protection Agency as a restricted usepesticide.[30] Because of its toxicity, distribution and use of chloropicrin is available only to licensed professionals and specially certified growers who are trained in its proper and safe use.[30] In the US, occupational exposure limits have been set at 0.1 ppm over an eight-hour time-weighted average.[31]
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Chloropicrin is harmful to humans. It can be absorbed systemically through inhalation, ingestion, and the skin. At high concentrations, it is severely irritating to the lungs, eyes, and skin.[32]
Chloropicrin and its derivativephosgene oxime have been known to damage or compromise earlier generations of personal protective equipment. Some of the soldiers attacked mentioned a white smoke emerging from their gas masks.[citation needed]
The Amended RED incorporated final new safety measures to increase protections for agricultural workers and bystanders. These measures establish a baseline for safe use of the soil fumigants throughout the United States, reducing fumigant exposures and significantly improving safety.
added controls for chloropicrin when it is used as a soil fumigant. The controls are intended to reduce risk from acute (short-term) exposures that might occur near fields fumigated with products containing chloropicrin.
The new measures appearing on soil fumigant Phase 2 labels include buffer zones and posting, emergency preparedness and response measures, training for certified applicators supervising applications, Fumigant Management Plans, and notice to State Lead Agencies who wish to be informed of applications in their states.
