Chemistry: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 | |
PubChem CID
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| UNII | |
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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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| Infobox references | |
Metam sodium is an organosulfur compound with the formula CH
3NHCS
2Na. 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]
Metam-sodium belongs to two HRAC groups, so it is designated Group A/C (Aus), Group A/C1 (global) and Group 1/5 (numeric).[4]
Preparation and properties
Metam sodium is prepared by combining methylamine, carbon disulfide, and sodium hydroxide:[2]
- CH
3NH
2 + CS
2 + NaOH → CH
3NHCS
2Na + H
2O
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.[5]
Safety and environmental considerations
Metam sodium is nonpersistent in the environment since it decomposes rather quickly to toxic methyl isothiocyanate and carbon disulfide.[5] 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.[6]
See also
- Zineb - A related dithiocarbamate salt which is also used as a fungicide
References
- ↑ 1.0 1.1 Merck Index, 11th Edition, 5860.
- ↑ 2.0 2.1 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 , U.S. Environmental Protection Agency
- ↑ Hertfordshire, University of. "Metam-sodium (Ref: N 869)". https://sitem.herts.ac.uk/aeru/ppdb/en/Reports/447.htm.
- ↑ 5.0 5.1 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. https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21740140.
- ↑ "Largest chemical spill in California history" (in en). https://dtsc.ca.gov/20th-anniversary-of-largest-chemical-spill-in-california-history/.
External links
- Metam sodium in the Pesticide Properties DataBase (PPDB)
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