Metam sodium
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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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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]
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 and other sulfur compounds.[4]
Safety and environmental considerations
[edit]Metam sodium is nonpersistent in the environment since it decomposes rather quickly to toxic methyl isothiocyanate and carbon disulfide.[4] In 1991 a tank car with 19,000 gallons of a metam sodium based pesticide spilled into Sacramento River above Lake Shasta. This killed all fish in a 41-mile stretch of the river. 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
- ^ a b Bretaudeau Deguigne M, Lagarce L, Boels D, Harry P (2011). "Metam sodium intoxication: the specific role of degradation products--methyl isothiocyanate and carbon disulphide--as a function of exposure". Clin Toxicol (Phila). 49 (5): 416–22. doi:10.3109/15563650.2011.585472. PMID 21740140.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ "Largest chemical spill in California history". dtsc.ca.gov. Retrieved 2017-12-11.
External links
[edit]- Metam sodium in the Pesticide Properties DataBase (PPDB)