Diphenylchlorarsine

Diphenylchlorarsine

Names
IUPAC name diphenylchloroarsenic, chlorodiphenylarsane, sneezing gas
Other names diphenylchlorarsine
Identifiers
CAS Number	712-48-1
3D model (Jmol)	Interactive image Interactive image
Abbreviations	Ph2AsCl
ChemSpider	12306
ECHA InfoCard	100.010.839
PubChem	12836
InChI InChI=1S/C12H10AsCl/c14-13(11-7-3-1-4-8-11)12-9-5-2-6-10-12/h1-10H Key: YHHKGKCOLGRKKB-UHFFFAOYSA-N InChI=1/C12H10AsCl/c14-13(11-7-3-1-4-8-11)12-9-5-2-6-10-12/h1-10H Key: YHHKGKCOLGRKKB-UHFFFAOYAA
SMILES Cl[As](C1=CC=CC=C1)C2=CC=CC=C2 Cl[As](c1ccccc1)c2ccccc2
Properties
Chemical formula	C12H10AsCl
Molar mass	264.59 g mol^−1
Appearance	colorless crystalline solid
Density	1.55 g/cm^3
Melting point	42 °C (108 °F; 315 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Diphenylchloroarsine (DA) is the organoarsenic compound 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 rings and one chloride.

Preparation and structure

It was first produced in 1878 by Michaelis and La Coste. It is prepared by the reduction of diphenylarsonic acid with sulfur dioxide. An idealized equation is shown:^[1]

Ph₂AsO₂H + SO₂ + HCl → Ph₂AsCl + H₂O + SO₃

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.^[2]

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)

Safety

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 dumped in northeastern China after Japan's numerous invasions of China, including chlorodiphenylarsine.^[3]

Chemical warfare

Diphenylchlorarsine was used as a chemical weapon on the Western front during the trench warfare of World War I.^[4] It belongs to the class of chemicals classified as vomiting agents. Other such agents are diphenylcyanoarsine (DC) and diphenylaminechlorarsine (DM, adamsite).^[5] 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 "Maskenbrecher", "mask breaker", together with other substances with similar effect: Adamsite, diphenylarsincyanide, diphenylaminarsincyanide. Fortunately, this gas did not actually penetrate masks any better than other gases.^[6]

References

1. Blicke, F. F.; Smith, F. D. (1929). "Action of Aromatic Grignard Reagents on Arsenic Trioxide". Journal of the American Chemical Society. 51 (5): 1558–1565. doi:10.1021/ja01380a038.
2. Trotter, J. (1962). "Stereochemistry of Arsenic. IV. Chlorodiphenylarsine". Canadian Journal of Chemistry. 40 (8): 1590–1593. doi:10.1139/v62-241.
3. "Abandoned Chemical Weapons (ACW) in China". 02/06/2004. Check date values in: |date= (help) Archived July 4, 2008, at the Wayback Machine.
4. Gilbert, M. (1995). The First World War—A Complete History. HarperCollins. ISBN 0805047344.
5. Holstege, C. P.; Boyle, J. S. (2008-11-26). "CBRNE - Vomiting Agents - Dm, Da, Dc". Medscape.
6. Gas and Flame in Modern Warfare, 1918, Chapter IX.