Phenyldichloroarsine
IUPAC name	dichloro-phenylarsane
Other names	Dichloro(phenyl)arsine
Identifiers
Abbreviations	PD (NATO)
CAS number	696-28-6
PubChem	12762
EC number	211-791-9
RTECS number	CH5425000
SMILES	Cl[As](Cl)c1ccccc1
InChI	nChI=1/C6H5AsCl2/c8-7(9)6-4-2-1-3-5-6/h1-5H/i1-12,2-12,3-12,4-12,5-12,6-12,7-75,8-35
Properties
Molecular formula	C6H5AsCl2
Molar mass	222.9315 [g/mol]
Appearance	Colorless gas or liquid
Density	1.65 g/cc (at 20 °C)
Melting point	-20 °C
Boiling point	252-255 °C
Solubility in water	insoluable
Solubility	acetone, ether, benzene
log P	3.060
Vapor pressure	.033
kH	3.00E-05 atm-m3/mole
Atmospheric OH rate constant	1.95E-12 cm3/molecule-sec
Hazards
MSDS	External MSDS
Main hazards	Flammability, incapacitation, blistering
NFPA 704	1 4 0
Flash point	16 °C
U.S. Permissible exposure limit (PEL)	0.5 mg/m2
LD50	2,500 mg - min/m3
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Phenyldichloroarsine, NATO abbreviation PD, is an organic arsenical vesicant and vomiting agent developed by Germany for use as a chemical warfare agent during World War I. The agent is known by multiple synonyms and is technically classified as a vesicant, or blister agent.

[edit] History

German chemists weaponized the first organic arsenical, methyldichloroarsine (MD), during World War I between 1917 and 1918.^[1] Phenyldichloroarsine and another organic arsenical, ethyldichloroarsine were soon added to the German arsenal.^[1][2]

[edit] Chemical characteristics

[edit] General

Phenyldichloroarsine is an odorless, colorless substance that can form hydrochloric acid upon contact with water.^[3] The reaction with water is very slow, the substance sinks, and the reaction is considered non-hazardous.^[4] Another product of hydrolysis is phenylarsenious acid, which is a severe irritant to the mucous membranes and skin.^[3] Most often found in a liquid state, the chemical is an organic dithiol-arsenical.^[3] In an impure state, phenyldichloroarsine may have a slight brown color, in its purest form though there is no color and the substance has an oily texture.^[5] An impure solution of PD also emits a characteristically unpleasant horseradish or garlic-like odor, which is detectable at .1 ppm.^[6]

Phenyldichloroarsine is one of four organic arsenicals, the other three are lewisite (L), methyldichloroarsine (MD),and ethyldichloroarsine (ED).^[1] PD is considered an analog of lewisite.^[7] At its freezing point, -20 °C, PD becomes a microcrystalline solid mass.^[8] The compound has a C-metalloid bond between the phenyl group and the arsenic and two covalent bonds between the arsenic and the chlorine.^[9]

[edit] Synthesis

Phenyldichloroarsine is produced by reacting benzene with arsenic trichloride. Anhydrous aluminum chloride acts as a catalyst in this reaction.^[5]

[edit] Uses

Phenyldichloroarsine is useful as a chemical warfare agent and is classified as a vesicant or a vomiting/incapacitating agent.^[10] It was used as a weapon during World War I, where it showed itself as less effective than other vomiting agents.^[10] The Japanese may also have used phenyldichloroarsine along with mustard agents and lewisite in China during World War II.^[11] Phenyldichloroarsine is an arsenical vesicant which is most often mixed with other mustard agents for use in chemical warfare.^[12] This does not increase the severity of its effects but does tend to confuse exposure diagnosis.^[12]

PD was developed for use in wet environments, because of its tendency to persist in cool and shaded areas.^[13] Phenyldichloroarsine can have a persistence lasting anywhere from 2 to 7 days under usual environmental conditions.^[5] In open areas, it is more useful as a vomiting agent but in closed-in areas, such as basements, trenches and caves, it is highly effective because of its "extreme" vapor density.^[13] Phenyldichloroarsine has also been used by banks and other high-security facilities to defend against security breaches.^[5]

[edit] Biological effects

PD damages the eyes, lungs, throat and nasal membranes.^[13] PD immediately affects the eyes and blindness can result, though it requires high doses.^[5] It also induces nausea and vomiting, an inhalation of as little as 5-50 milligrams can induce severe vomiting.^[5] Long-term exposure to PD can cause systemic damage by replacing calcium with arsenic, extensive bone marrow damage can also result.^[13] Due to PD being easily recognized in the field and a relatively fast rate for decontamination procedures to become effective, the chemical is not as useful as other blister agents.^[5] The blistering resultant from PD exposure may also be delayed, for as little as 30 minutes,^[7] or as long as 32 hours depending upon the concentration of the dose.^[5]

The molecular toxicology of PD is not well understood,^[7] but a 1986 U.S. Army-sponsored report did shed some light on that area. The Army report showed that PD penetrated the red blood cell membrane and interacted with something inside the cell. The study also found that hemoglobin was not responsible for "holding" the PD in its bond with the erythrocytes (red blood cells), instead glutathione was found to be a more likely interacting with PD inside the cell .^[7][13]

[edit] See also

• Diphenylchlorarsine

[edit] References