Trimethylarsine

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Trimethylarsine
Structural formula of trimethylarsine with an implicit electron pair
Ball and stick model of trimethylarsine
Names
Preferred IUPAC name
Trimethanidoarsenic
Systematic IUPAC name
Trimethylarsane
Other names
Gosio gas
Identifiers
593-88-4 N
1730780
ChEBI CHEBI:27130 YesY
ChemSpider 62200 YesY
EC Number 209-815-8
141657
Jmol 3D model Interactive image
Interactive image
MeSH Trimethylarsine
PubChem 68978
RTECS number CH8800000
  • InChI=1S/C3H9As/c1-4(2)3/h1-3H3 YesY
    Key: HTDIUWINAKAPER-UHFFFAOYSA-N YesY
  • InChI=1/C3H9As/c1-4(2)3/h1-3H3
    Key: HTDIUWINAKAPER-UHFFFAOYAT
  • [As](C)(C)C
  • C[As](C)C
Properties
C3H9As
Molar mass 120.03 g·mol−1
Appearance Colourless liquid
Density 1.124 g cm−3
Melting point −87.3 °C (−125.1 °F; 185.8 K)
Boiling point 56 °C (133 °F; 329 K)
Slightly soluble
Solubility in other solvents organic solvents
Structure
Trigonal pyramidal
0.86 D
Vapor pressure {{{value}}}
Related compounds
Related compounds
 Cacodylic acid
Triphenylarsine
Supplementary data page
Refractive index (n),
Dielectric constant (εr), etc.
Thermodynamic
data
 Phase behaviour
solid–liquid–gas
UV, IR, NMR, MS
N verify (what is YesYN ?)
Infobox references

Trimethylarsine is the chemical compound with the formula (CH3)3As, commonly abbreviated AsMe3 or TMAs. This organic derivative of arsine has been used as a source of arsenic in microelectronics industry,[1] a building block to other organoarsenic compounds, and serves as a ligand in coordination chemistry. It has distinct "garlic"-like smell. Trimethylarsine had been discovered as early as 1854.

Structure and preparation

As predicted by VSEPR theory, AsMe3 is a pyramidal molecule. The As-C distances average 1.519 Å, and the C-As-C angles are 91.83°[2] This bond angle is a strong indication of a low, if any, hybridisation of the atomic orbitals, leaving the lone pair in the s-orbital buried in the inner regions of the arsenic atom, rather than pointing outward like the lone pair of the ammonia molecule.

Trimethylarsine can be prepared by treatment of arsenic oxide with trimethylaluminium:[3]

As2O3 + 1.5 [AlMe3]2 → 2 AsMe3 + 3/n (MeAl-O)n

Properties and reactions

Trimethylarsine is pyrophoric due to the exothermic nature of the following reaction, which initiates combustion:

AsMe3 + 1/2 O2 → OAsMe3 (TMAO)

History

Poisoning events due to a gas produced by certain microbes was assumed to be associated with the arsenic in paint. In 1893 the Italian physician Bartolomeo Gosio published his results on "Gosio gas" that was subsequently shown to contain trimethylarsine.[4] Under wet conditions, the mold Scopulariopsis brevicaulis produces significant amounts of methyl arsines via methylation[5] of arsenic-containing inorganic pigments, especially Paris green and Scheele's Green, which were once used in indoor wallpapers. Newer studies show that trimethylarsine has a low toxicity and could therefore not account for the death and the severe health problems observed in the 19th century.[6] [7]

Safety

Trimethylarsine is potentially hazardous,[8][9][10] although its toxicity is often overstated.[6]

Importance

Trimethylarsine is the volatile byproduct of microbial action on inorganic forms of arsenic which are naturally occurring in rocks and soils at the parts-per-million level.[11] Trimethylarsine has been reported only at trace levels (parts per billion) in landfill gas from Germany, Canada, and the U.S.A., and is the major arsenic-containing compound in the gas.[12][13][14]

References

  1. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ V. V. Gavrilenko, L. A. Chekulaeva, and I. V. Pisareva, "Highly efficient synthesis of trimethylarsine" Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 2122–2123, 1996.
  4. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ 6.0 6.1 Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.

External links

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