Metam sodium

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Metam sodium [1]
Metham sodium.png
Metham sodium 3D ball.png
Names
Preferred IUPAC name
Sodium methylcarbamodithioate
Other names
Metham sodium
Carbathion
Carbathione
Carbothion
Metamsodium
Metam-sodium
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.004.812 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/C2H5NS2.Na/c1-3-2(4)5;/h1H3,(H2,3,4,5);/q;+1/p-1 Yes check.svgY
    Key: AFCCDDWKHLHPDF-UHFFFAOYSA-M Yes check.svgY
  • [Na+].[S-]C(=S)NC
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]

Contents

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]

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. [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

References

  1. 1 2 Merck Index , 11th Edition, 5860.
  2. 1 2 Hartwig, Jürgen; Sommer, Herbert; Müller, Franz (2008). "Nematicides". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a17_125.pub2. ISBN   978-3527306732.
  3. ↑ 2000-2001 Pesticide Market Estimates Archived 2009-02-07 at the Wayback Machine , U.S. Environmental Protection Agency
  4. ↑ Hertfordshire, University of. "Metam-sodium (Ref: N 869)". sitem.herts.ac.uk.
  5. 1 2 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. Archived from the original on May 23, 2024.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. ↑ "Largest chemical spill in California history". dtsc.ca.gov. Retrieved 2017-12-11.
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