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]

Names
Preferred IUPAC name Sodium methylcarbamodithioate
Other names Metham sodium Carbathion Carbathione Carbothion Metamsodium Metam-sodium
Identifiers
CAS Number	137-42-8 Y
3D model (JSmol)	Interactive image
ChemSpider	2273119 Y
ECHA InfoCard	100.004.812
PubChem CID	5366415
UNII	3CD7UKN224 Y
CompTox Dashboard (EPA)	DTXSID2029167
InChI InChI=1S/C2H5NS2.Na/c1-3-2(4)5;/h1H3,(H2,3,4,5);/q;+1/p-1 Y Key: AFCCDDWKHLHPDF-UHFFFAOYSA-M Y
SMILES [Na+].[S-]C(=S)NC
Properties
Chemical formula	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). Y verify (what is YN ?) Infobox references

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

• Zineb - A related dithiocarbamate salt which is also used as a fungicide