phosgene oxime

Phosgene oxime can be prepared by reduction of chloropicrin using a combination of tin metal and hydrochloric acid as the source of the active hydrogen reducing agent:

:{{chem2|Cl3CNO2 + 4 [H] → Cl2C\dN\sOH + HCl + H2O}}

The observation of a transient violet color in the reaction suggests intermediate formation of trichloronitrosomethane (Cl₃CNO). Early preparations, using stannous chloride as the reductant, also started with chloropicrin.{{cite journal |author1=Prandtl, W. |author2=Dollfus, W. | title = Über das Trichlor-nitroso-methan, das Dichlor-formoxim (Phosgen-oxim) und einige ihrer Derivate, 2. Mitteilung: Über zwei neue Derivate der Kohlensäure | journal = Berichte der Deutschen Chemischen Gesellschaft | year = 1932 | volume = 65B |issue=5 | pages = 754–9 | doi = 10.1002/cber.19320650515}}

The compound is electrophilic and thus sensitive to nucleophiles, including bases, which destroy it:

:{{chem2|Cl2CNOH + 2 NaOH → CO2 + NH2OH + 2 NaCl + H2O}}

Phosgene oxime has been used to prepare heterocycles that contain N-O bonds, such as isoxazoles.{{cite journal |doi=10.1021/jo502634h|title=Tandem Synthesis of 3-Chloro-4-iodoisoxazoles from 1-Copper(I) Alkynes, Dichloroformaldoxime, and Molecular Iodine|year=2015|last1=Chen|first1=Wenwen|last2=Zhang|first2=Jianlan|last3=Wang|first3=Bo|last4=Zhao|first4=Zhouxing|last5=Wang|first5=Xinyan|last6=Hu|first6=Yuefei|journal=The Journal of Organic Chemistry|volume=80|issue=4|pages=2413–2417|pmid=25594794}}

Dehydrohalogenation upon contact with mercuric oxide generates chlorine fulminate, a reactive nitrile oxide:{{cite journal |doi=10.1021/JP981262E|title=Unstable Chloronitrile Oxide, ClCNO, and Its Stable Ring Dimer: Generation, Spectroscopy, and Structure|year=1998|last1=Pasinszki|first1=Tibor|last2=Westwood|first2=Nicholas P. C.|journal=The Journal of Physical Chemistry A|volume=102|issue=25|pages=4939–4947|bibcode=1998JPCA..102.4939P}}

:{{chem2|Cl2CNOH → Cl\sC\tN+\sO− + HCl}}

Phosgene oxime is classified as a vesicant even though it does not produce blisters.{{cite journal | last1 = McManus | first1 = J | last2 = Huebner | first2 = K | title = Vesicants | journal = Critical Care Clinics | year = 2005 | volume = 21 | issue = 4 | pages = 707–718 | doi = 10.1016/j.ccc.2005.06.005| pmid = 16168310 | url = https://zenodo.org/record/1258826}} It is toxic by inhalation, ingestion, or skin contact. The effects of the poisoning occur almost immediately. No antidote for phosgene oxime poisoning is known. Generally, any treatment is supportive. Typical physical symptoms of CX exposure are as follows:

• Skin: Blanching surrounded by an erythematous ring can be observed within 30 seconds of exposure. A wheal develops on exposed skin within 30 minutes. The original blanched area acquires a brown pigmentation by 24 hours. An eschar forms in the pigmented area by 1 week and sloughs after approximately 3 weeks. Initially, the effects of CX can easily be misidentified as mustard gas exposure. However, the onset of skin irritation resulting from CX exposure is a great deal faster than mustard gas, which typically takes several hours or more to cause skin irritation.
• Eyes: Eye examination typically demonstrates conjunctivitis, lacrimation, lid edema, and blepharospasm after even minute exposures. More severe exposures can result in keratitis, iritis, corneal perforation, and blindness.
• Respiratory: Irritation of the mucous membranes may be observed on examination of the oropharynx and nose. Evidence of pulmonary edema, including rales and wheezes, may be noted on auscultation. Pulmonary thromboses are prominent features of severe CX exposure.
• Gastrointestinal: Some animal data suggest that CX may cause hemorrhagic inflammatory changes in the GI tract.

{{Reflist}}

• [http://www.emedicine.com/emerg/topic903.htm EMedicine: Urticants, Phosgene Oxime]
• [https://web.archive.org/web/20131229033312/http://bioterrorism.slu.edu/bt/products/ahec_chem/scripts/PhosgeneOxime.pdf Center for the Study of Bioterrorism: Phosgene Oxime]
• [https://web.archive.org/web/20060110155811/http://www.bt.cdc.gov/agent/phosgene-oxime/basics/facts.asp Centers for Disease Control: Facts About Phosgene Oxime]
• [https://web.archive.org/web/20051122235728/http://www.vnh.org/MedAspChemBioWar/chapters/chapter_7.htm#Phosgene%20Oxime Virtual Naval Hospital: Phosgene Oxime]

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Category:Chemical weapons

Category:Organochlorides

Category:Oximes