Arsine

Arsine
Image:Arsine.png
General
Systematic name	Arsane
Other names	Arsenic trihydride
Molecular formula	AsH3
Molar mass	77.95 g/mol
Appearance	colourless gas
CAS number	[7784-42-1]
Properties
Density and phase	4.93 g/l, gas
Solubility in water	0.07 g/100 ml (25 °C)
Solubility in organic solvents	soluble
Melting point	-117 °C (157 K)
Boiling point	-62.5 °C (210 K)
Basicity (pKb)	?
Structure
Molecular shape	trigonal pyramidal
Dipole moment	0.20 D
Thermodynamic data
Standard enthalpy of formation ΔfHogas	+171.5 kJ/mol
Standard molar entropy Sogas	? J.K−1.mol−1
Hazards
MSDS	External MSDS
EU classification	Very flammable Highly toxic Dangerous for the environment
NFPA 704
R-phrases	R12, R26, R48/20 R50/53
S-phrases	S1/2, S9, S16, S28, S33, S36/37, S45, S60, S61
Flash point	flammable gas
Autoignition temperature	? °C
Explosive limits	4.5–78
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Related hydrides	Ammonia Phosphine Stibine
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

Arsine (AsH₃) is a flammable and highly toxic gaseous chemical compound of arsenic and hydrogen. Synonyms include arseniuretted hydrogen, arsenous hydride, arsenic trihydride, and hydrogen arsenide. Some organic compounds based on arsine, such as lewisite, adamsite, Clark I and Clark II, have been developed for chemical warfare.

Arsine is also used in the semiconductor industry for depositing arsenic.

Arsine was formed temporarily, and then decomposed, in the old (but extremely sensitive) Marsh test for the presence of arsenic.

Toxicology

For the toxicology of other arsenic compounds, see Arsenic, Arsenic trioxide and Arsenicosis.

The toxicity of arsine is distinct from that of other arsenic compounds. The main route of exposure is by inhalation, although poisoning after skin contact has also been described. Arsine binds to the haemaglobin of red blood cells, causing them to be destroyed by the body.

The first signs of exposure, which can take several hours to become apparent, are headches, vertigo and nausea, followed by the syptoms of haemolytic anaemia (high levels of unconjugated bilirubin), haemaglobinuria and nephropathy. In severe cases, the damage to the kidneys can be long-lasting.

Exposure to arsine concentrations of 250 ppm is rapidly fatal: concentrations of 25–30 ppm are fatal for 30 min exposure, and concentrations of 10 ppm can be fatal at longer exposure times. Symptoms of poisoning appear after exposure to concentrations of 0.5 ppm. There is little information on the chronic toxicity of arsine, although it is reasonable to assume that, in common with other arsenic compounds, a long-term exposure could lead to arsenicosis.

See also

• Arsenic
• Cacodylic acid
• Cacodyl oxide

Bibliography

Institut national de recherche et de sécurité (INRS), Fiche toxicologique nº 53 : Trihydrure d'arsenic, 2000.

External links

• International Chemical Safety Card 0222
• IARC Monograph "Arsenic and Arsenic Compunds"
• NIOSH Pocket Guide to Chemical Hazards
• European Chemicals Bureau
• Institut national de recherche et de sécurité, France (in French)
• NIST Chemistry WebBook
• Data on arsine from Air Liquide