Clopyralid
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 | |
| Names | |
|---|---|
| Preferred IUPAC name
3,6-Dichloropyridine-2-carboxylic acid | |
| Other names
3,6-Dichloropicolinic acid | |
| Identifiers | |
3D model (JSmol) |
|
| Abbreviations | 3,6-DCP |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.015.396 |
| KEGG | |
PubChem CID |
|
| UNII | |
CompTox Dashboard (EPA) |
|
| |
| |
| Properties | |
| C6H3Cl2NO2 | |
| Molar mass | 192.00 |
| Appearance | White crystalline solid |
| Melting point | 150 to 152 °C (302 to 306 °F; 423 to 425 K) |
| ~1000 ppm | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |
Clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) is a selective herbicide used for control of broadleaf weeds, especially thistles and clovers. Clopyralid is in the picolinic acid family of herbicides, which also includes aminopyralid, picloram, triclopyr, and several less common herbicides.[2][3]
Synthesis
[edit]The synthesis of clopyralid begins with picoline, which is photochemically chlorinated. The resulting trichloromethyl group is subsequently oxidized to a carboxyl group using nitric acid.[4]
Uses
[edit]
Clopyralid serves as an active ingredient in pesticides.[5] The compound was introduced in 1975 by Dow Chemical as a selective, systemic auxin herbicide.
It is primarily used as a post-emergence herbicide in sugar beets and fodder beets to control various weeds, such as thistles, coltsfoot, cornflowers, knotweed, and chamomile. Clopyralid is also used in the cultivation of cereals, canola, corn, onions, and strawberries, as well as on ornamental shrubs and grassland.[6] It is most effective during periods of vigorous plant growth.[7]
For control of creeping thistle, Cirsium arvense, a noxious, perennial weed, clopyralid is one of the few effective herbicides available. It is particularly damaging to peas, tomatoes, and sunflowers, and can render potatoes, lettuce, and spinach inedible.[8] It does not affect grasses (family Poaceae).[citation needed]
Approval
[edit]Clopyralid is known for its ability to persist in dead plants and compost, and has accumulated to phytotoxic levels in finished compost in a few highly publicized cases. This first came to light in Washington, when during 2000 and 2001, residues of clopyralid were detected in commercial compost, and compost made at a municipal site damaged tomatoes and other garden plants planted in it. Word quickly spread to other local and state governments, and in 2002, Dow AgroSciences, the manufacturer of clopyralid, voluntarily deregistered it for use on domestic lawns in the US[9] and it is banned in several US states, but it is found in consumer products in Europe such as Scotts Verdone Extra and Vitax Lawn Clear 2.[8]
Clopyralid is used in Australia on industrial areas and agriculturally, to control broadleaf weeds in wheat, barley, oats, triticale, and fallow.[10]
Clopyralid is licensed for lawn use in France and under these names: Bayer Jardin: Désherbant jeune gazon and Scanner Sélectif gazon Vilmorin: désherbant Gazon LONPAR. Brand names of clopyralid in the US market include Stinger, Transline, Reclaim,[2][11] Curtail, Confront, Clopyr AG, Lontrel, Millennium Ultra, Millenium Ultra Plus and Redeem.
References
[edit]- ↑ Merck Index, 11th Edition, 2398.
- 1 2 Staff, Virginia Tech Cooperative Extension. Revised May 14, 2012 Pyridine Herbicide Carryover: Causes and Precautions Archived 2016-11-30 at the Wayback Machine Accessed May 27, 2013
- ↑ Bob Hartzler, extension weed management specialist, Department of Agronomy, Iowa State University. February 21, 2006 Aminopyralid - New herbicide for pastures, roadsides, etc. Archived 2014-11-03 at the Wayback Machine Accessed May 27, 2013
- ↑ Thomas A. Unger (1996), "Clopyralid", Pesticide Synthesis Handbook, Park Ridge NJ: Noyes Publications, p. 530, ISBN 0-8155-1401-8
- ↑ Record of 3,6-Dichlorpyridin-2-carbonsäure in the GESTIS Substance Database of the Institute for Occupational Safety and Health
- ↑ Entry on Clopyralid. at: Römpp Online. Georg Thieme Verlag, retrieved {{{Datum}}}.
- ↑ Archived (Date missing) at plantan.de (Error: unknown archive URL) S. 4.
- 1 2 Moody, Oliver (23 February 2013). "Weedkiller banned in US 'is getting into compost and killing garden vegetables'". The Times. London.
- ↑ David E. Haskell, California Department of Pesticide Regulation Clopyralid in Compost[permanent dead link] 2003 Proceedings of the California Weed Science Society 55:163-166
- ↑ "4Farmers Clopyralid 300". 4farmers.com.au. 4Farmers Australia.
- ↑ "Herbicide Resistant Weeds". Archived from the original on 2011-07-18. Retrieved 2011-03-07.
