Diphenylchlorarsine

It was first produced in 1878 by the German chemists August Michaelis (1847–1916) and Wilhelm La Coste (1854–1885). It is prepared by the reduction of diphenylarsinic acid with sulfur dioxide. An idealized equation is shown: :Ph2AsO2H + SO2 + HCl → Ph2AsCl + H2SO4 The process adopted by Edgewood Arsenal, the "sodium process", for the production of DA for chemical warfare purposes, employed a reaction between chlorobenzene and arsenic trichloride in the presence of sodium. DA is characterized by being the most difficult of the arsenic-based chemical warfare agents to synthesize. For example, in comparison, DM (Adamsite) requires only one manufacturing step and is applied in one-pot. PD, although manufactured in a very similar way to DA, is much more simpler to separate from the by-products. ==Uses==

It is a useful reagent for the preparation of other diphenylarsenic compounds, e.g. by reactions with Grignard reagents: :RMgBr + (C6H5)2AsCl → (C6H5)2AsR + MgBrCl :(R = alkyl, aryl) Chemical warfare Diphenylchlorarsine was used as a chemical weapon on the Western front during the trench warfare of World War I. It belongs to the class of chemicals classified as vomiting agents. Other such agents are diphenylcyanoarsine (DC) and diphenylaminechlorarsine (DM, Adamsite). Diphenylchlorarsine was sometimes believed to penetrate the gas masks of the time and to cause violent sneezing, forcing removal of the protecting device. The Germans called it (mask breaker), together with other substances with similar effects, such as Adamsite, diphenylarsincyanide, and diphenylaminarsincyanide. This gas did not actually penetrate masks any better than other gases. DA (military code and acronym for diphenylchloroarsine) is a precursor to DC (diphenylcyanoarsine), generated by the reaction of an aqueous solution of sodium cyanide and DA (DC process, NaCN method), with cyanide being used in excess of 5%, for military purposes. ==Toxicity==

Diphenylchlorarsine is known to cause sneezing, coughing, headache, salivation, and vomiting. China and Japan are negotiating remediation of stocks of a variety of organoarsenic weapons, including diphenylchlorarsine, dumped in northeastern China after Japan's numerous invasions of China. ==See also==