Phosgene oxime, or CX, is an organic compound with the formula Cl2C\dN\sOH. It is a potent chemical weapon, specifically a nettle agent. The compound itself is a colorless solid, but impure samples are often yellowish liquids. It has a strong, disagreeable and irritating odor. It is used as a reagent in organic chemistry.

Preparation and reactions

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: 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. The compound is electrophilic and thus sensitive to nucleophiles, including bases, which destroy it: Phosgene oxime has been used to prepare heterocycles that contain N-O bonds, such as isoxazoles. Dehydrohalogenation upon contact with mercuric oxide generates chlorine fulminate, a reactive nitrile oxide:

Toxicity

Phosgene oxime is classified as a vesicant even though it does not produce blisters. 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: