Trimethylarsine

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Template:Chembox header | Trimethylarsine
Structural formula of trimethylarsine
Ball-and-stick model of arsine
Template:Chembox header | General
Systematic name Trimethylarsine
Other names Gosio Gas
Molecular formula C3H9As
Molar mass 120.02 g/mol
Appearance Colorless liquid
CAS number [593-88-4]
Template:Chembox header | Properties
Density and phase 1.124 g/cm³
Solubility in water Slightly soluble
Other solvents organic solvents
Melting point -87.3 °C
Boiling point 51 °C
Template:Chembox header | Structure
geometry Trigonal pyramidal
Dipole moment 0.86 D
Related compounds Cacodylic acid
Triphenylarsine
Template:Chembox header | Hazards
MSDS External MSDS
Main hazards Flammable
NFPA 704
Flash point 100 °C
R/S statement R: ?
S: ?
See www.sigmaaldrich.com
RTECS number CH8800000
Template:Chembox header | Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Template:Chembox header | Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Infobox disclaimer and references

Trimethylarsine is the chemical compound with the formula (CH3)3As, commonly abbreviated AsMe3. This organic derivative of arsine (AsH3) has been used as a source of arsenic in microelectronics industry. It is known for it's distinct "garlic" like smell. Trimethylarsine had been discovered as early as 1854.

Structure and Preparation

As predicted by VSEPR theory, AsMe3 is pyramidal with As-C distance of 1.519 Å and C-As-C angles 91.83°[1]

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

As2O3 + 3 AlMe3 → 2 AsMe3 + Me-(Al-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

Although poisoning events due to a gas produced by certain micobes was observed and the dependence to the arsenic in paint was assumed. It was not until 1893 that the Italian physician Bartolomeo Gosio published his results on the toxic "Gosio gas" which was subsequently shown to be trimethylarsine.[2]. Under wet conditions mold (scopulariopsis brevicaulis was an very active species) produces significant amounts of arsenic via biomethylation of inorganic pigments especially Paris green or Scheele's Green used in indoor wallpapers which is than released into the air. Newer studies show that trimethylearsine has a low toxicity and could therefor not account for the death and the severe health problems observed in the 19th century.[3]

Safety

Like all organoarsenic compounds, it is considered a carcinogen.

References

  1. *Wells, A.F.
  2. *Challenger, F.
  3. William R. Cullen, Ronald Bentley (2005). "The toxicity of trimethylarsine: an urban myth". J. Environ. Monit. 7: 11–15. doi:10.1039/b413752n.
  • Challenger, F.; et al. (1933). "The Formation of Organo-Metalloid Compounds by Microorganisms: Part I. Trimethylarsine and Dimethylethylarsine". J. Chem. Soc., 95-101, 1933.
  • Wells, A.F. (1984). Structural Inorganic Chemistry, fifth edition. Oxford University Press. ISBN-10: 0198553706. [1]
  • Andrewes, Paul; et al. (2003). "Dimethylarsine and Trimethylarsine Are Potent Genotoxins In Vitro". Chem. Res. Toxicol., 16 (8), 994 -1003, 2003.
  • Irvin, T.Rick; et al. (1995). "In-vitro Prenatal Toxicity of Trimethylarsine, Trimethylarsine Oxide and Trimethylarsine Sulfide". Applied Organometallic Chemistry. vol. 9.315-321.
  • Sokolovskii, A.E. (2001). "Thermal Decomposition of Trimethylarsine". Kinetics and Catalysis, Vol 42, No. 6, 2001, pp. 743-745.
  • Hoshino, Masataka (1991). "A mass spectrometric study of the decomposition of trimethylarsine (TMAs) with triethylgallium (TEGa)". Journal of Crystal Growth 110(1991)704-712.

External links

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de:Trimethylarsen