Metam sodium

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]

Metam sodium[1]
Ball-and-stick model of the component ions of metham sodium
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
UNII
  • InChI=1S/C2H5NS2.Na/c1-3-2(4)5;/h1H3,(H2,3,4,5);/q;+1/p-1 checkY
    Key: AFCCDDWKHLHPDF-UHFFFAOYSA-M checkY
  • [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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Infobox references

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.[4]

Safety and environmental considerations

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

References
  1. Merck Index, 11th Edition, 5860.
  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. Review of Metam Sodium, Dazomet, Methylisothiocyanate (MITC) Archived 2009-07-13 at the Wayback Machine, Australian Pesticides and Veterinary Medicines Authority, June 1997
  5. "Largest chemical spill in California history". dtsc.ca.gov. Retrieved 2017-12-11.
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