Metam sodium
Chemical compound
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. 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.
Metam-sodium belongs to two HRAC groups, so it is designated Group A/C (Aus), Group A/C1 (global) and Group 1/5 (numeric).
01Preparation and properties
Metam sodium is prepared by combining methylamine, carbon disulfide, and sodium hydroxide:
- CH3NH2 + CS2 + NaOH → CH3NHCS2Na + H2O
It also arises from the reaction of methyl isothiocyanate and sodium thiolate.
Upon exposure to the environment, metam sodium decomposes to methyl isothiocyanate and other sulfur compounds.
02Safety and environmental considerations
Metam sodium is nonpersistent in the environment since it decomposes rather quickly to toxic methyl isothiocyanate and carbon disulfide. 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.
Sources and credits
This article is adapted from the Wikipedia article “Metam sodium”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- Metham sodium.png by Edgar181, Public domain
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