Metam sodium is an organosulfur compound with the formula CH3NHCS2Na. The compound is a sodium salt of a dithiocarbamate. The compound exists as a colorless dihydrate, but most commonly it is encountered as an aqueous solution.[2] It is used as a soil fumigant, pesticide, herbicide, and fungicide. It is one of the most widely used pesticides in the United States, with approximately 60 million pounds used in 2001.[3]
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| Names | |
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| Preferred IUPAC name
Sodium methylcarbamodithioate | |
| Other names
Metham sodium
Carbathion Carbathione Carbothion Metamsodium Metam-sodium | |
| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.004.812 |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| C2H4NNaS2 | |
| Molar mass | 129.18 g/mol |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Preparation and properties edit
Metam sodium is prepared by combining methylamine, carbon disulfide, and sodium hydroxide:[2]
- CH3NH2 + CS2 + NaOH → CH3NHCS2Na + H2O
It also arises from the reaction of methyl isothiocyanate and sodium thiolate.[1]
Upon exposure to the environment, metam sodium decomposes to methyl isothiocyanate.[4]
Safety and environmental considerations edit
Metam sodium is nonpersistent in the environment since it is prone to hydrolysis. The degradation products, carbon disulfide and methyl amine are however toxic. In 1991 a tank car with 19,000 gallons of metam sodium spilled into Sacramento River above Lake Shasta. This killed all fish in a 41-mile stretch of the river. By 20 years later the rainbow trout population had recovered.[5]
See also edit
- Zineb - A related dithiocarbamate salt which is also used as a fungicide
References edit
- ^ a b Merck Index, 11th Edition, 5860.
- ^ a b Hartwig, Jürgen; Sommer, Herbert; Müller, Franz (2008). "Nematicides". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a17_125.pub2. ISBN 978-3527306732.
- ^ 2000-2001 Pesticide Market Estimates Archived 2009-02-07 at the Wayback Machine, U.S. Environmental Protection Agency
- ^ Review of Metam Sodium, Dazomet, Methylisothiocyanate (MITC) Archived 2009-07-13 at the Wayback Machine, Australian Pesticides and Veterinary Medicines Authority, June 1997
- ^ "Largest chemical spill in California history". dtsc.ca.gov. Retrieved 2017-12-11.
External links edit
- Metam sodium in the Pesticide Properties DataBase (PPDB)