Arsine

Arsine (IUPAC name: arsane) is an inorganic compound with the formula AsH3. This flammable, pyrophoric, and highly toxic pnictogen hydride gas is one of the simplest compounds of arsenic.[4] Despite its lethality, it finds some applications in the semiconductor industry and for the synthesis of organoarsenic compounds. The term arsine is commonly used to describe a class of organoarsenic compounds of the formula AsH3−xRx, where R = aryl or alkyl. For example, As(C6H5)3, called triphenylarsine, is referred to as "an arsine".

Not to be confused with arcsine.
Arsine
Names
IUPAC names
Arsenic trihydride
Arsane
Trihydridoarsenic
Other names
Arseniuretted hydrogen,
Arsenous hydride,
Hydrogen arsenide
Arsenic hydride
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.029.151
EC Number
  • 232-066-3
599
KEGG
RTECS number
  • CG6475000
UNII
UN number 2188
Properties
AsH3
Molar mass 77.9454 g/mol
Appearance Colourless gas
Density 4.93 g/l, gas; 1.640 g/mL (−64 °C)
Melting point −111.2 °C (−168.2 °F; 162.0 K)
Boiling point −62.5 °C (−80.5 °F; 210.7 K)
0.07 g/100 ml (25 °C)
Vapor pressure 14.9 atm[1]
Conjugate acid Arsonium
Structure
Trigonal pyramidal
0.20 D
Thermochemistry
223 J⋅K−1⋅mol−1
+66.4 kJ/mol
Hazards
Main hazards Explosive, flammable, potential occupational carcinogen[1]
Safety data sheet See: data page
GHS pictograms
GHS Signal word Danger
H220, H330, H373, H400, H410
P210, P260, P271, P273, P284, P304+340, P310, P314, P320, P377, P381, P391, P403, P403+233, P405, P501
NFPA 704 (fire diamond)
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propaneHealth code 4: Very short exposure could cause death or major residual injury. E.g. VX gasReactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazards (white): no code
4
4
2
Flash point −62 °C (−80 °F; 211 K)
Explosive limits 5.1–78%[1]
Lethal dose or concentration (LD, LC):
2.5 mg/kg (intravenous)[2]
  • 120 ppm (rat, 10 min)
  • 77 ppm (mouse, 10 min)
  • 201 ppm (rabbit, 10 min)
  • 108 ppm (dog, 10 min)[3]
  • 250 ppm (human, 30 min)
  • 300 ppm (human, 5 min)
  • 25 ppm (human, 30 min)[3]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 0.05 ppm (0.2 mg/m3)[1]
REL (Recommended)
 C 0.002 mg/m3 [15-minute][1]
IDLH (Immediate danger)
 3 ppm[1]
Related compounds
Related hydrides
 Ammonia; phosphine; stibine; bismuthine
Supplementary data page
Refractive index (n),
Dielectric constant (εr), etc.
Thermodynamic
data
 Phase behaviour
solid–liquid–gas
UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

General properties

At its standard state, arsine is a colorless, denser-than-air gas that is slightly soluble in water (20% at 20 °C) and in many organic solvents as well. Whereas arsine itself is odorless, owing to its oxidation by air it is possible to smell a slight garlic or fish-like scent when the compound is present above 0.5 ppm.[5] This compound is generally regarded as stable, since at room temperature it decomposes only slowly. At temperatures of ca. 230 °C decomposition to arsenic and hydrogen is rapid. Several factors, such as humidity, presence of light and certain catalysts (namely aluminium) facilitate the rate of decomposition.[6]

AsH3 is a pyramidal molecule with H–As–H angles of 91.8° and three equivalent As–H bonds, each of 1.519 Å length.[7]

Discovery and synthesis

AsH3 is generally prepared by the reaction of As3+ sources with H− equivalents.[8]

4 AsCl3 + 3 NaBH4 → 4 AsH3 + 3 NaCl + 3 BCl3

As reported in 1775, Carl Scheele reduced arsenic(III) oxide with zinc in the presence of acid.[9] This reaction is a prelude to the Marsh test, described below.

Alternatively, sources of As3− react with protonic reagents to also produce this gas. Zinc arsenide and sodium arsenide are suitable precursors:[10]

Zn3As2 + 6 H+ → 2 AsH3 + 3 Zn2+
Na3As + 3 HBr → AsH3 + 3 NaBr

Reactions

The understanding of the chemical properties of AsH3 is well developed and can be anticipated based on an average of the behavior of PH3 and SbH3.

Thermal decomposition

Typical for a heavy hydride (e.g., SbH3, H2Te, SnH4), AsH3 is unstable with respect to its elements. In other words, AsH3 is stable kinetically but not thermodynamically.

2 AsH3 → 3 H2 + 2 As

This decomposition reaction is the basis of the Marsh Test described below, which detects the elemental As.

Oxidation

Continuing the analogy to SbH3, AsH3 is readily oxidized by concentrated O2 or the dilute O2 concentration in air:

2 AsH3 + 3 O2 → As2O3 + 3 H2O

Arsine will react violently in presence of strong oxidizing agents, such as potassium permanganate, sodium hypochlorite, or nitric acid.[6]

Precursor to metallic derivatives

AsH3 is used as a precursor to metal complexes of "naked" (or "nearly naked") As. Illustrative is the dimanganese species [(C5H5)Mn(CO)2]2AsH, wherein the Mn2AsH core is planar.[11]

Gutzeit test

A characteristic test for arsenic involves the reaction of AsH3 with Ag+, called the Gutzeit test for arsenic.[12] Although this test has become obsolete in analytical chemistry, the underlying reactions further illustrate the affinity of AsH3 for "soft" metal cations. In the Gutzeit test, AsH3 is generated by reduction of aqueous arsenic compounds, typically arsenites, with Zn in the presence of H2SO4. The evolved gaseous AsH3 is then exposed to AgNO3 either as powder or as a solution. With solid AgNO3, AsH3 reacts to produce yellow Ag4AsNO3, whereas AsH3 reacts with a solution of AgNO3 to give black Ag3As.

Acid-base reactions

The acidic properties of the As–H bond are often exploited. Thus, AsH3 can be deprotonated:

AsH3 + NaNH2 → NaAsH2 + NH3

Upon reaction with the aluminium trialkyls, AsH3 gives the trimeric [R2AlAsH2]3, where R = (CH3)3C.[13] This reaction is relevant to the mechanism by which GaAs forms from AsH3 (see below).

AsH3 is generally considered non-basic, but it can be protonated by superacids to give isolable salts of the tetrahedral species [AsH4]+.[14]

Reaction with halogen compounds

Reactions of arsine with the halogens (fluorine and chlorine) or some of their compounds, such as nitrogen trichloride, are extremely dangerous and can result in explosions.[6]

Catenation

In contrast to the behavior of PH3, AsH3 does not form stable chains, although H2As–AsH2 and even H2As–As(H)–AsH2 have been detected. The diarsine is unstable above −100 °C.

Applications

Microelectronics applications

AsH3 is used in the synthesis of semiconducting materials related to microelectronics and solid-state lasers. Related to phosphorus, arsenic is an n-dopant for silicon and germanium.[6] More importantly, AsH3 is used to make the semiconductor GaAs by chemical vapor deposition (CVD) at 700–900 °C:

Ga(CH3)3 + AsH3 → GaAs + 3 CH4

For microelectronic applications, arsine can be provided via a sub-atmospheric gas source. In this type of gas package, the arsine is adsorbed on a solid microporous adsorbent inside a gas cylinder. This method allows the gas to be stored without pressure, significantly reducing the risk of an arsine gas leak from the cylinder. With this apparatus, arsine is obtained by applying vacuum to the gas cylinder valve outlet. For semiconductor manufacturing, this method is feasible, as processes such as ion implantation operate under high vacuum.

Chemical warfare

Since before WWII AsH3 was proposed as a possible chemical warfare weapon. The gas is colorless, almost odorless, and 2.5 times denser than air, as required for a blanketing effect sought in chemical warfare. It is also lethal in concentrations far lower than those required to smell its garlic-like scent. In spite of these characteristics, arsine was never officially used as a weapon, because of its high flammability and its lower efficacy when compared to the non-flammable alternative phosgene. On the other hand, several organic compounds based on arsine, such as lewisite (β-chlorovinyldichloroarsine), adamsite (diphenylaminechloroarsine), Clark 1 (diphenylchloroarsine) and Clark 2 (diphenylcyanoarsine) have been effectively developed for use in chemical warfare.[15]

Forensic science and the Marsh test

AsH3 is also well known in forensic science because it is a chemical intermediate in the detection of arsenic poisoning. The old (but extremely sensitive) Marsh test generates AsH3 in the presence of arsenic.[4] This procedure, published in 1836 by James Marsh,[16] is based upon treating an As-containing sample of a victim's body (typically the stomach contents) with As-free zinc and dilute sulfuric acid: if the sample contains arsenic, gaseous arsine will form. The gas is swept into a glass tube and decomposed by means of heating around 250–300 °C. The presence of As is indicated by formation of a deposit in the heated part of the equipment. On the other hand, the appearance of a black mirror deposit in the cool part of the equipment indicates the presence of antimony (the highly unstable SbH3 decomposes even at low temperatures).

The Marsh test was widely used by the end of the 19th century and the start of the 20th; nowadays more sophisticated techniques such as atomic spectroscopy, inductively coupled plasma, and x-ray fluorescence analysis are employed in the forensic field. Though neutron activation analysis was used to detect trace levels of arsenic in the mid 20th century, it has since fallen out of use in modern forensics.

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 attacks hemoglobin in the red blood cells, causing them to be destroyed by the body.[17][18]

The first signs of exposure, which can take several hours to become apparent, are headaches, vertigo, and nausea, followed by the symptoms of haemolytic anaemia (high levels of unconjugated bilirubin), haemoglobinuria and nephropathy. In severe cases, the damage to the kidneys can be long-lasting.[1]

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.[3] 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.

It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities.[19]

Occupational exposure limits
Country Limit[20]
Argentina Confirmed human carcinogen
Australia TWA 0.05 ppm (0.16 mg/m3)
Belgium TWA 0.05 ppm (0.16 mg/m3)
Bulgaria Confirmed human carcinogen
Colombia Confirmed human carcinogen
Denmark TWA 0.01 ppm (0.03 mg/m3)
Egypt TWA 0.05 ppm (0.2 mg/m3)
France
  • VME 0.05 ppm (0.2 mg/m3)
  • VLE 0.2 ppm (0.8 mg/m3)
Hungary TWA 0.2 mg/m3STEL 0.8 mg/m3
Japan
  • Occupational exposure limit 0.01 ppm (0.032 mg/m3)
  • Continuous 0.1 ppm (0.32 mg/m3)
Jordan Confirmed human carcinogen
Mexico TWA 0.05 ppm (0.2 mg/m3)
Netherlands MAC-TCG 0.2 mg/m3
New Zealand TWA 0.05 ppm (0.16 mg/m3)
Norway TWA 0.003 ppm (0.01 mg/m3)
Philippines TWA 0.05 ppm (0.16 mg/m3)
Poland TWA 0.2 mg/m3 STEL 0.6 mg/m3
Russia STEL 0.1 mg/m3
Singapore Confirmed human carcinogen
South Korea TWA 0.05 ppm (0.2 mg/m3)
Sweden TWA 0.02 ppm (0.05 mg/m3)
Switzerland MAK-week 0.05 ppm (0.16 mg/m3)
Thailand TWA 0.05 ppm (0.2 mg/m3)
Turkey TWA 0.05 ppm (0.2 mg/m3)
United Kingdom TWA 0.05 ppm (0.16 mg/m3)
United States 0.05 ppm (0.2 mg/m3)
Vietnam Confirmed human carcinogen

See also

References
  1. NIOSH Pocket Guide to Chemical Hazards. "#0040". National Institute for Occupational Safety and Health (NIOSH).
  2. Levvy, G.A. (1946). "The Toxicity of Arsine Administered by Intraperitoneal Injection". British Journal of Pharmacology and Chemotherapy. 1 (4): 287–290. doi:10.1111/j.1476-5381.1946.tb00049.x. PMC 1509744. PMID 19108099.
  3. "Arsine". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  4. Holleman, A. F.; Wiberg, E. (2001) Inorganic Chemistry Academic Press: San Diego, ISBN 0-12-352651-5.
  5. "Medical Management Guidelines for Arsine (AsH3)". Agency for Toxic Substances & Disease Registry.
  6. Institut National de Recherche et de Sécurité (2000). "Fiche toxicologique nº 53: Trihydrure d'arsenic" (PDF). Archived from the original (PDF) on 2006-11-26. Retrieved 2006-09-06. Cite journal requires |journal= (help)
  7. Nielsen H. H. (1952). "The Molecular Structure of Arsine". The Journal of Chemical Physics. 20 (12): 1955–1956. Bibcode:1952JChPh..20.1955N. doi:10.1063/1.1700347.
  8. Bellama, J. M.; MacDiarmid, A. G. (1968). "Synthesis of the Hydrides of Germanium, Phosphorus, Arsenic, and Antimony by the Solid-Phase Reaction of the Corresponding Oxide with Lithium Aluminum Hydride". Inorganic Chemistry. 7 (10): 2070–2. doi:10.1021/ic50068a024.
  9. Scheele, Carl Wilhelm (1775) "Om Arsenik och dess syra" (On arsenic and its acid), Kongliga Vetenskaps Academiens Handlingar (Proceedings of the Royal Scientific Academy [of Sweden]), 36: 263-294. From p. 290: "Med Zinck. 30. (a) Denna år den endaste af alla så hela som halfva Metaller, som i digestion met Arsenik-syra effervescerar." (With zinc. 30. (a) This is the only [metal] of all whole- as well as semi-metals that effervesces on digestion with arsenic acid.) Scheele collected the arsine and put a mixture of arsine and air into a cylinder. From p. 291: "3:0, Då et tåndt ljus kom når o̊pningen, tåndes luften i kolfven med en småll, lågan for mot handen, denna blef o̊fvedragen med brun fårg, … " (3:0, Then as [the] lit candle came near the opening [of the cylinder], the gases in [the] cylinder ignited with a bang; [the] flame [rushed] towards my hand, which became coated with [a] brown color, … )
  10. "Arsine" in Handbook of Preparative Inorganic Chemistry, 2nd ed., G. Brauer (ed.), Academic Press, 1963, NY, Vol. 1. p. 493.
  11. Herrmann, W. A.; Koumbouris, B.; Schaefer, A.; Zahn, T.; Ziegler, M. L. (1985). "Generation and Complex Stabilization of Arsinidene and Diarsine Fragments by Metal-Induced Degradation of Monoarsine". Chemische Berichte. 118 (6): 2472–88. doi:10.1002/cber.19851180624.
  12. King, E. J. (1959) Qualitative Analysis and Electrolytic Solutions Harcourt, Brace, and World; New York
  13. Atwood, D. A.; Cowley, A. H.; Harris, P. R.; Jones, R. A.; Koschmieder, S. U.; Nunn, C. M.; Atwood, J. L.; Bott, S. G. (1993). "Cyclic Trimeric Hydroxy, Amido, Phosphido, and Arsenido Derivatives of aluminum and gallium. X-ray Structures of [tert-Bu2Ga(m-OH)]3 and [tert-Bu2Ga(m-NH2)]3". Organometallics. 12: 24–29. doi:10.1021/om00025a010.
  14. R. Minkwitz, R.; Kornath, A.; Sawodny, W.; Härtner, H. (1994). "Über die Darstellung der Pnikogenoniumsalze AsH4+SbF6−, AsH4+AsF6−, SbH4+SbF6−". Zeitschrift für Anorganische und Allgemeine Chemie. 620 (4): 753–756. doi:10.1002/zaac.19946200429.
  15. Suchard, Jeffrey R. (March 2006). "CBRNE — Arsenicals, Arsine". EMedicine. Retrieved 2006-09-05.
  16. Marsh, James (1836). "Account of a method of separating small quantities of arsenic from substances with which it may be mixed". Edinburgh New Philosophical Journal. 21: 229–236.
  17. Fowler B. A.; Weissberg J. B. (1974). "Arsine poisoning". New England Journal of Medicine. 300 (22): 1171–1174. doi:10.1056/NEJM197411282912207. PMID 4608634.
  18. Hatlelid K. M. (1996). "Reactions of Arsine with Hemoglobine". Journal of Toxicology and Environmental Health Part A. 47 (2): 145–157. doi:10.1080/009841096161852. PMID 8598571.
  19. "40 C.F.R.: Appendix A to Part 355—The List of Extremely Hazardous Substances and Their Threshold Planning Quantities" (PDF) (July 1, 2008 ed.). Government Printing Office. Archived from the original (PDF) on February 25, 2012. Retrieved October 29, 2011. Cite journal requires |journal= (help)
  20. "Arsine". RTECS. National Institute for Occupational Safety and Health (NIOSH).
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