Arsine

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Structural formula
Structure of arsine
General
Surname Arsine
other names
  • Monoarsan
  • Arsan ( IUPAC )
  • Arsine
  • Arsenic hydride
Molecular formula AsH 3
Brief description

colorless gas with an unpleasant smell of garlic

External identifiers / databases
CAS number
  • 7784-42-1
  • 65423-90-7 (hexahydrate)
EC number 232-066-3
ECHA InfoCard 100.029.151
PubChem 23969
ChemSpider 22408
Wikidata Q334599
properties
Molar mass 77.95 g mol −1
Physical state

gaseous

density

3.52 kg m −3

Melting point

−116.9 ° C

boiling point

−62.48 ° C

Vapor pressure

1.6 M Pa (20 ° C)

solubility

very heavy in water (200 mg l −1 )

Dipole moment

0.217 (3) D (7.2 x 10 -31  C  ·  m )

Refractive index

1.352 (16.85 ° C)

safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary
06 - Toxic or very toxic 02 - Highly / extremely flammable 08 - Dangerous to health
04 - gas bottle 09 - Dangerous for the environment

danger

H and P phrases H: 330-220-373-280-410
P: 260-210-273-304 + 340-315-308 + 313-377-381-405-403
MAK
  • DFG : canceled
  • Switzerland: 0.05 ml m −3 or 0.16 mg m −3
Toxicological data

25 ppm 30 min ( LC 50humaninh. )

Thermodynamic properties
ΔH f 0

66.4 kJ / mol

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Arsenic hydrogen (monoarsane, arsine, arsenic hydride) is a chemical compound made up of the elements arsenic and hydrogen with the empirical formula AsH 3 . It is an extremely poisonous gas that is produced when salt-like arsenides are dissolved in water and dilute acids.

The term "arsine" is also often used for all arsenic-hydrogen compounds ( see Arsane ).

history

During World War arsine was as green cross - warfare agent used.

Extraction and presentation

Technically, arsine is produced in a one-step reaction by acid hydrolysis of arsenides. The hydrolysis of zinc arsenide in non-oxidizing, aqueous acid ( e.g. sulfuric acid ) is common and very easy to carry out :

With careful selection of the starting materials, very pure arsine can be produced in this way. Diarsan , which is unstable above −100 ° C, is a by-product . Furthermore, the hydrogenation of arsenic (III) chloride (AsCl 3 ) using LiAlH 4 or NaBH 4 also provides pure arsine.

Arsenic hydrogen can be obtained from arsenic (III) oxide using nascent hydrogen:

Furthermore, the reactions of calcium and sodium arsenide with water produce arsine. Will take regular water deuterium oxide used, the result is arsine d 3 .

As well as the conversion of sodium arsenide with ammonium bromide in liquid ammonia .

The electrochemical production of arsine is also a viable route that is rapidly gaining importance. The electrochemical synthesis allows the relatively targeted ad-hoc production of defined amounts of arsine. The first patents for the electrochemical production of arsine and other hydrides were published in the early 1990s.

properties

Physical Properties

structure

Arsenic hydrogen is a pyramidal molecule with the three hydrogen atoms at the triangular pyramid base and the arsenic atom at the top. The bond angle H – As – H, at 91.83 °, is somewhat smaller than the tetrahedral angle of 109.5 °, because on the one hand the free electron pair on arsenic exerts greater electrostatic repulsion than the binding electron pairs. On the other hand, the As-H bond length of 0.1519 nm means that the repulsive forces between the centers of the electrical charge of two As-H bonds are in equilibrium at smaller bond angles.

Arsenic has a weak electrical dipole moment of 0.22 Debye .

Arsenic hydrogen is gaseous and extremely toxic. It is colorless and, due to almost always present impurities, has a slightly garlic-like smell. The odor threshold is above the former MAK value of 50  ppb . The gas liquefies at −62.48 ° C (boiling point) and turns into a solid state at −116.93 ° C (melting point). The value for the standard enthalpy of formation of +66.44 kJ / mol at 25 ° C shows that arsine is an endothermic chemical compound. This means that the formation of the molecule consumes more energy than is released during the reaction. The standard molar entropy is 222.7 J / (mol · K) at 25 ° C.

Chemical properties

Arsenic is an unstable compound that easily breaks down into its components when heated:

If arsine is burned or passed through a glass tube heated to red heat and then hits a chilled porcelain bowl, a shiny metallic black arsenic mirror is formed. This chemical reaction is used for the analytical detection of arsenic ( see Marsh's sample ).

In the presence of air, arsine burns with a pale blue flame to form arsenic (III) oxide and water:

If there is not enough air or if the combustion temperature is cooler, only the hydrogen burns. Arsenic remains in the form of black arsenic. The same behavior is also observed when burning hydrogen sulphide .

In contrast to ammonia (NH 3 ), arsine (AsH 3 ) is not a base . In aqueous solution it acts as a strong reducing agent . When added to silver nitrate solution, metallic silver precipitates :

At temperatures below −10 ° C or under pressure, the hexahydrate is formed in the presence of water.

use

Despite its past as a chemical weapon , arsine is now a common technical product. In semiconductor technology , arsine is used as a doping gas on a large scale and in significant quantities in the context of thermal doping of silicon in the diffusion process and in ion implantation .

The disposal of arsine residues is very problematic because not only arsine itself, but also all arsine by-products are extremely toxic or harmful to health. It is customary to adsorption on activated carbon. After use, the loaded activated carbon must be disposed of as hazardous waste in special deep landfills.

Antidotes for arsine poisoning

In the case of poisoning, dimercaptopropane sulfonic acid (DMPS): Dimaval or dimercaptopropane sulfonate is administered as an antidote in emergency clinics . It is ( RS ) -2,3-dimercapto-1-propanesulfonic acid. However, some doctors consider DMPS to be ineffective.

safety instructions

Arsenic is the most toxic compound of arsenic. If you are exposed to a concentration of 20 mg / m³ for more than 50 minutes, this is fatal ( lethal concentration ). 3–10 mg / m³ cause symptoms of poisoning after several hours . It is particularly important to ensure that emergency measures are taken immediately if contact with arsine is suspected, as the hemolysis triggered by arsine can occur with a delay. Emergency clinics are usually overwhelmed with the treatment of arsine poisoning, which occurs very rarely. The available literature does not give clear instructions for action. Therefore, users should definitely consult the nearest emergency clinic beforehand for treatment in an emergency.

Compounds derived from arsine

If one , two or three hydrogen atoms in arsine AsH 3 are replaced by organic functional groups , organic arsanes are formed .

See also

Web links

Individual evidence

  1. a b c Entry on arsine. In: Römpp Online . Georg Thieme Verlag, accessed on July 15, 2014.
  2. a b c d e f g h Entry on arsine in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
  3. David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Dipole Moments, pp. 9-51.
  4. PG Sennikov, VE Shkrunin, DA Raldugin, KG Tokhadze: Weak Hydrogen Bonding in Ethanol and Water Solutions of Liquid Volatile Inorganic Hydrides of Group IV-VI Elements (SiH 4 , GeH 4 , PH 3 , AsH 3 , H 2 S, and H 2 Se). 1. IR Spectroscopy of H Bonding in Ethanol Solutions in Hydrides . In: The Journal of Physical Chemistry . tape 100 , no. January 16 , 1996, ISSN  0022-3654 , pp. 6415-6420 , doi : 10.1021 / jp953245k .
  5. Entry on Arsine in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
  6. Swiss Accident Insurance Fund (Suva): Limit values ​​- current MAK and BAT values , accessed on November 2, 2015.
  7. ^ Entry on arsine in the ChemIDplus database of the United States National Library of Medicine (NLM) .
  8. David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-5.
  9. G. Brauer (Ed.): Handbook of Preparative Inorganic Chemistry. 2nd ed., Vol. 1, Academic Press 1963, pp. 593-595.
  10. John E. Drake and Chris Riddle: Arsine and arsine- d 3 . In: FA Cotton (Ed.): Inorganic Syntheses . tape 13 . McGraw-Hill Book Company, Inc., 1972, ISBN   07-013208-9  ( defective ) , p. 14-17 (English).
  11. a b c d G. O. Doak, G. Gilbert Long, Leon D. Freedman: Arsenic Compounds . In: Kirk-Othmer Encyclopedia of Chemical Technology . John Wiley & Sons, Inc., 2000, p. 2 f ., doi : 10.1002 / 0471238961.0118190504150111.a01 .