Trimethylarsine
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
- ↑ *Wells, A.F.
- ↑ *Challenger, F.
- ↑ 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
- Index by Molecular Formula
- Information on Hazardous Chemicals by Class
- "Highly efficient synthesis of trimethylarsine" E E Gavrilenko, L. A. ChekulaePa,* and L E Pisareva
- Microbial Methylation of Metalloids: Arsenic, Antimony, and Bismuth
- Arsenic Curiosa and Humanity