Diphenylchloroarsine (DA) is the

organoarsenic compound Organoarsenic chemistry is the chemistry of Chemical compound, compounds containing a chemical bond between arsenic and carbon. A few organoarsenic compounds, also called "organoarsenicals," are produced industrially with uses as insecticides, herb ...

with the formula (C₆H₅)₂AsCl. It is highly toxic and was once used in chemical warfare. It is also an intermediate in the preparation of other organoarsenic compounds. The molecule consists of a pyramidal As(III) center attached to two

phenyl In organic chemistry, the phenyl group, or phenyl ring, is a cyclic group of atoms with the formula , and is often represented by the symbol Ph (archaically φ) or Ø. The phenyl group is closely related to benzene and can be viewed as a benzene ...

rings and one

chloride The term chloride refers to a compound or molecule that contains either a chlorine anion (), which is a negatively charged chlorine atom, or a non-charged chlorine atom covalently bonded to the rest of the molecule by a single bond (). The pr ...

. It was also known as sneezing oil during

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

by the Allies.

Preparation and structure

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 Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...

. 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 Chlorobenzene (abbreviated PhCl) is an aryl chloride and the simplest of the chlorobenzenes, consisting of a benzene ring substituted with one chlorine atom. Its chemical formula is C6H5Cl. This colorless, flammable liquid is a common solvent a ...

and arsenic trichloride in the presence of

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

. The German process, used in the first war, applied at Hochstam-Main, used the Sandmeyer reaction between phenyldiazonium chloride and

sodium arsenite Sodium arsenite usually refers to the inorganic compound with the formula NaAsO2. Also called sodium ''meta''-arsenite, it is an inorganic polymer consisting of the infinite chains sO2associated with sodium cations, Na+. The polymer backbone ...

. The acidified product was reduced and then neutralized. The salt was condensed again by the Sandmeyer reaction and reduced again, the final product was then acidified, resulting in DA.CHEMICAL CORPS CHEMICAL AND RADIOLOGICAL LABORATORIES. Army Chemical Center Maryland. Project: 4-72-05-005. 25 October, 1954 The structure consists of pyramidal As centre. The As-Cl distance is 2.26 A and the Cl-As-C and C-As-C angles are 96 and 105°, respectively.

Uses

It is a useful

reagent In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...

for the preparation of other diphenylarsenic compounds, e.g. by reactions with

Grignard reagent Grignard reagents or Grignard compounds are chemical compounds with the general formula , where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride and phenylmagnesium bromi ...

s: :RMgBr + (C₆H₅)₂AsCl → (C₆H₅)₂AsR + MgBrCl :(R =

alkyl In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl group is derived from a cy ...

aryl In organic chemistry, an aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar" is used ...

)

Chemical warfare

Diphenylchlorarsine was used as a chemical weapon on the Western front during the trench warfare of

. 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 A sneeze (also known as sternutation) is a semi-autonomous, convulsive expulsion of air from the lungs through the nose and mouth, usually caused by foreign particles irritating the nasal mucosa. A sneeze expels air forcibly from the mouth a ...

coughing A cough is a sudden expulsion of air through the large breathing passages which can help clear them of fluids, irritants, foreign particles and microbes. As a protective reflex, coughing can be repetitive with the cough reflex following three ...

headache A headache, also known as cephalalgia, is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of Depression (mood), depression in those with severe ...

, salivation, and

vomiting Vomiting (also known as emesis, puking and throwing up) is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenteritis, pre ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

and

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

are negotiating remediation of stocks of a variety of organoarsenic weapons, including diphenylchlorarsine, dumped in northeastern China after Japan's numerous invasions of China.

References

{{Chemical agents Chemical weapons Organoarsenic chlorides Vomiting agents Phenyl compounds Arsenic(III) compounds

Preparation and structure

Uses

Chemical warfare

Toxicity

See also

References