:Chloropicrin

Chloropicrin was discovered in 1848 by Scottish chemist John Stenhouse. He prepared it by the reaction of sodium hypochlorite with picric acid:

{{block indent|{{chem2|HOC6H2(NO2)3 + 11 NaOCl → 3 Cl3CNO2 + 3 Na2CO3 + 3 NaOH + 2 NaCl}}}}

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

Today, chloropicrin is manufactured by the reaction of nitromethane with sodium hypochlorite:{{cite encyclopedia |first=Sheldon B. |last=Markofsky |title=Nitro Compounds, Aliphatic |encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry |publisher=Wiley-VCH |location=Weinheim |year=2005}}

{{block indent|{{chem2|H3CNO2 + 3 NaOCl → Cl3CNO2 + 3 NaOH}}}}

Reaction of chloroform and nitric acid also yields chloropicrin:{{cite journal |title=Chloropicrin |first=Kirby E. |last=Jackson |journal=Chemical Reviews |year=1934 |volume=14 |issue=2 |pages=251–286 |url=https://doi.org/10.1021/cr60048a003 |doi=10.1021/cr60048a003|url-access=subscription }}

{{block indent|{{Chem2|Cl3CH + HONO2 -> Cl3CNO2 + H2O}}}}

Chloropicrin's chemical formula is {{chem2|CCl3NO2}} and its molecular weight is 164.38 grams/mole.{{cite web|title=Executive Summary - Evaluation of Chloropicrin As A Toxic Air Contaminant|url=http://www.cdpr.ca.gov/docs/emon/pubs/tac/exec_sum_0210.pdf|publisher=Department of Pesticide Regulation - California Environmental Protection Agency|access-date=20 September 2013|page=iv|date=February 2010|archive-url=https://web.archive.org/web/20131006220801/http://www.cdpr.ca.gov/docs/emon/pubs/tac/exec_sum_0210.pdf|archive-date=6 October 2013|url-status=dead}} Pure chloropicrin is a colorless liquid, with a boiling point of 112 °C. Chloropicrin is sparingly soluble in water with solubility of 2 g/L at 25 °C. It is volatile, with a vapor pressure of 23.2 millimeters of mercury (mmHg) at 25 °C; the corresponding Henry's law constant is 0.00251 atmosphere-cubic meter per mole. The octanol-water partition coefficient (K_ow) of chloropicrin is estimated to be 269. Its soil adsorption coefficient (K_oc; normalized to soil organic matter content) is 25 cm³/g.

Chloropicrin was manufactured for use as poison gas in World War I.{{cite book |last=Ayres |first=Leonard P. |title =The War with Germany |url=https://archive.org/details/warwithgermanya02ayregoog |publisher =United States Government Printing Office |edition =2nd |date =1919 |location =Washington, DC |page =[https://archive.org/details/warwithgermanya02ayregoog/page/n86 80]}} In World War I, German forces used concentrated chloropicrin against Allied forces as a tear gas. While not as lethal as other chemical weapons, it induced vomiting and forced Allied soldiers to remove their masks to vomit, exposing them to more toxic gases used as weapons during the war.{{Cite journal |last=Heller |first=Charles E. |date=September 1984 |title=Chemical Warfare in World War I: The American Experience, 1917–1918 |url=https://www.armyupress.army.mil/Portals/7/combat-studies-institute/csi-books/leavenworth-papers-10-chemical-warfare-in-world-war-i-the-american-experience-1917-1918.pdf |journal=Leavenworth Papers |issue=10 |pages=23}}

In February 2024, Ukrainian General Oleksandr Tarnavskyi accused the Russian Armed Forces of using chloropicrin munitions.{{cite web |title=Ukraine accuses Russia of intensifying chemical attacks on the battlefield |url=https://www.reuters.com/world/europe/ukraine-accuses-russia-intensifying-chemical-attacks-battlefield-2024-02-09/ |website=Reuters |access-date=2024-02-10}} In May 2024, the United 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.{{cite web |title=Imposing New Measures on Russia for its Full-Scale War and Use of Chemical Weapons Against Ukraine |url=https://www.state.gov/imposing-new-measures-on-russia-for-its-full-scale-war-and-use-of-chemical-weapons-against-ukraine-2/ |publisher=United States Department of State |access-date=2 May 2024}}

In agriculture, chloropicrin is injected into soil prior to planting a crop to fumigate soil. Chloropicrin affects a broad spectrum of fungi, microbes and insects.{{cite web |url=http://www.workcover.nsw.gov.au/Documents/Publications/AlertsGuidesHazards/DangerousGoodsExplosivesFireworksPyrotechnics/chloropicrin_fact_sheet_1371.pdf |title=Factsheet: Chloropicrin |location=New South Wales |publisher=WorkCover |archive-url=https://web.archive.org/web/20090520095913/http://www.workcover.nsw.gov.au/Documents/Publications/AlertsGuidesHazards/DangerousGoodsExplosivesFireworksPyrotechnics/chloropicrin_fact_sheet_1371.pdf |archive-date=May 20, 2009}} It is commonly used as a stand-alone treatment or in combination / co-formulation with methyl bromide and 1,3-dichloropropene.{{cite book| first1 = Amos Alfred |last1=Fries|first2=Clarence Jay |last2=West| title = Chemical warfare| url = https://archive.org/details/chemicalwarfare00westgoog| year = 1921| publisher = McGraw-Hill | page = [https://archive.org/details/chemicalwarfare00westgoog/page/n160 144]}} Chloropicrin is used as an indicator and repellent when fumigating residences for insects with sulfuryl fluoride which is an odorless gas.{{cn|date=December 2024}} Chloropicrin's mode of action is unknown (IRAC MoA 8B). Chloropicrin may stimulate weed germination, which can be useful when quickly followed by a more effective herbicide.{{cite journal | last=Martin | first=Frank N. | title=Development of Alternative Strategies for Management of Soilborne Pathogens Currently Controlled with Methyl Bromide | journal=Annual Review of Phytopathology | publisher=Annual Reviews | volume=41 | issue=1 | year=2003 | issn=0066-4286 | doi=10.1146/annurev.phyto.41.052002.095514 | pages=325–350| pmid=14527332}}

Chloropicrin was first registered in 1975 in the US. After a 2008 re-approval, the EPA{{cite web |title=RED Fact Sheet: Chloropicrin|url=https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P1010HX8.txt

|publisher=US Environmental Protection Agency|access-date=20 September 2013|page=2|date=10 July 2008}} 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."{{cite web|title=Amended Reregistration Eligibility Decision (RED) for Chloropicrin|url=http://www.epa.gov/oppsrrd1/REDs/chloropicrin-red-amended.pdf|archive-url=https://web.archive.org/web/20131006211550/http://www.epa.gov/oppsrrd1/REDs/chloropicrin-red-amended.pdf|url-status=dead|archive-date=October 6, 2013|publisher=United States Environmental Protection Agency|access-date=20 September 2013|date=May 2009}}{{cite web|title=Chloropicrin Mitigation Proposal|url=http://www.cdpr.ca.gov/docs/whs/pdf/dpr_chloropicrin_mitigation_proposal_and_app_1-3.pdf|publisher=Department of Pesticide Regulation – California Environmental Protection Agency|access-date=20 September 2013|page=2|date=15 May 2013|archive-url=https://web.archive.org/web/20131006220459/http://www.cdpr.ca.gov/docs/whs/pdf/dpr_chloropicrin_mitigation_proposal_and_app_1-3.pdf|archive-date=6 October 2013|url-status=dead}} 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.{{cite web|title=Chloropicrin – Background|url=http://www.chloropicrinfacts.org/background.html|access-date=20 September 2013}} EPA protections were increased in both 2011 and 2012, reducing fumigant exposures and significantly improving safety.{{cite web|title=Chloropicrin Mitigation Proposal|url=http://www.cdpr.ca.gov/docs/whs/pdf/dpr_chloropicrin_mitigation_proposal_and_app_1-3.pdf|publisher=Department of Pesticide Regulation – California Environmental Protection Agency|access-date=20 September 2013|page=2|date=15 May 2013|quote=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.|archive-url=https://web.archive.org/web/20131006220459/http://www.cdpr.ca.gov/docs/whs/pdf/dpr_chloropicrin_mitigation_proposal_and_app_1-3.pdf|archive-date=6 October 2013|url-status=dead}} 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.{{cn|date=December 2024}}

Used as a preplant soil treatment measure, chloropicrin suppresses soilborne pathogenic fungi and some nematodes and insects. According to chloropicrin manufacturers, with a half-life of hours to days, it is completely digested by soil organisms before the crop is planted, making it safe and efficient.{{cn|date=May 2024}} Contrary to popular belief, chloropicrin does not sterilize soil and does not deplete the ozone layer, as the compound is destroyed by sunlight. Additionally, chloropicrin has never been found in groundwater, due to its low solubility.{{cite web |url= https://www.plantmanagementnetwork.org/edcenter/seminars/potato/Chloropicrin/ |title=Chloropicrin Soil Fumigation in Potato Production Systems|work=Plant Management Network |publisher=American Phytopathological Society |access-date= 1 Apr 2019}}

In California, experience with acute effects of chloropicrin when used as a soil fumigant for strawberries and other crops led to the release of regulations in January 2015 creating buffer zones and other precautions to minimize exposure of farm workers, neighbors, and passersby.{{cite web|title=Control Measures for Chloropicrin|url=http://www.cdpr.ca.gov/docs/whs/pdf/control_measures_chloropicrin_summary.pdf|publisher=California Department of Pesticide Regulation|access-date=January 15, 2015|date=January 6, 2015|quote=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.|archive-url=https://web.archive.org/web/20150128143316/http://www.cdpr.ca.gov/docs/whs/pdf/control_measures_chloropicrin_summary.pdf|archive-date=January 28, 2015|url-status=dead}}{{cite web|title=Chloropicrin Mitigation Proposal|url=http://www.cdpr.ca.gov/docs/whs/pdf/dpr_chloropicrin_mitigation_proposal_and_app_1-3.pdf|publisher=Department of Pesticide Regulation – California Environmental Protection Agency|access-date=20 September 2013|page=2|date=15 May 2013|quote=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.|archive-url=https://web.archive.org/web/20131006220459/http://www.cdpr.ca.gov/docs/whs/pdf/dpr_chloropicrin_mitigation_proposal_and_app_1-3.pdf|archive-date=6 October 2013|url-status=dead}}

At a national level, chloropicrin is regulated in the United States by the United States Environmental Protection Agency as a restricted use pesticide.{{cite web|title=Chloropicrin Mitigation Proposal|url=http://www.cdpr.ca.gov/docs/whs/pdf/dpr_chloropicrin_mitigation_proposal_and_app_1-3.pdf|publisher=Department of Pesticide Regulation – California Environmental Protection Agency|access-date=20 September 2013|page=1|date=15 May 2013|archive-url=https://web.archive.org/web/20131006220459/http://www.cdpr.ca.gov/docs/whs/pdf/dpr_chloropicrin_mitigation_proposal_and_app_1-3.pdf|archive-date=6 October 2013|url-status=dead}} Because of its toxicity and carcinogenicity, distribution and use of chloropicrin is available only to licensed professionals and specially certified growers who are trained in its proper and safe use. In the US, occupational exposure limits have been set at 0.1 ppm over an eight-hour time-weighted average.{{cite web|title = NIOSH Pocket Guide to Chemical Hazards|url=https://www.cdc.gov/niosh/npg/npgd0132.html|publisher=Centers for Disease Control and Prevention|access-date=7 November 2013}}

File:"Chlorpicrin, it smelled like flypaper" (OHA 365), National Museum of Health and Medicine (5405373108).jpg

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.{{cite web |url=https://www.cdc.gov/niosh/ershdb/EmergencyResponseCard_29750034.html |title=Chloropicrin (PS): Lung Damaging Agent |publisher=National Institute for Occupational Safety and Health |work=Emergency Response Safety and Health Database |date=August 22, 2008 |access-date=December 23, 2008}}

Chloropicrin and its derivative phosgene 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|date=July 2022}}

• Trichloronitrosomethane
• Tetrachlorodinitroethane

{{reflist|refs=

{{cite web|url=http://irac-online.org/documents/moa-classification/|title=IRAC Mode of Action Classification Scheme Version 9.4|website=IRAC (Insecticide Resistance Action Committee)|type=pdf|date=March 2020}}

{{PPDB|148}}, University of Hertfordshire, accessed 2021-03-10.

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{{Chemical warfare}}

Category:World War I chemical weapons

Category:Fumigants

Category:Pulmonary agents

Category:Lachrymatory agents

Category:Vomiting agents

Category:Nitro compounds

Category:Trichloromethyl compounds

Category:Fungicides

Category:Herbicides

Category:Insecticides

Category:Nematicides