Title: Clopyralid
CAS Registry Number: 1702-17-6
CAS Name: 3,6-Dichloro-2-pyridinecarboxylic acid
Additional Names: 3,6-dichloropicolinic acid; 3,6-DCP
Manufacturers' Codes: Dowco 290
Molecular Formula: C6H3Cl2NO2
Molecular Weight: 192.00
Percent Composition: C 37.53%, H 1.57%, Cl 36.93%, N 7.30%, O 16.67%
Literature References: Systemic post-emergence herbicide for use in food crops and mesquite. Prepn: H. Johnston, BE 644105; idem, US 3317549 (1964, 1967 both to Dow). Alternate process: S. D. McGregor, US 4087431 (1978 to Dow). Physicochemical properties, toxicity and herbicidal activity: J. G. Brown, S. D. Uprichard, Proc. Br. Crop Prot. Conf. - Weeds 1976, 119. GLC determn: A. J. Pik, G. W. Hodgson, J. Assoc. Off. Anal. Chem. 59, 264 (1976). Persistence in soil: A. J. Pik et al., J. Agric. Food Chem. 25, 1054 (1977). Field trial in mesquite control: R. W. Bovey, R. E. Meyer, Weed Sci. 33, 349 (1985).
Properties: White, odorless crystalline solid, mp 151-152°. Vapor pressure at 25°: 1.2´10-5 mm Hg. Soly at 25°: ~1000 ppm in water, >25% w/w in methanol, acetone, xylene. LD50 in male, female rats (mg/kg): >5000, 4300 orally; LC50 (96 hr) to rainbow trout: 103.5 mg/l (Brown, Uprichard).
Melting point: mp 151-152°
Toxicity data: LD50 in male, female rats (mg/kg): >5000, 4300 orally; LC50 (96 hr) to rainbow trout: 103.5 mg/l (Brown, Uprichard)
Derivative Type: Monoethanolamine salt
CAS Registry Number: 57754-85-5
Trademarks: Dow Shield (Dow AgroSci.); Lontrel (Dow AgroSci.); Reclaim (Dow AgroSci.); Stinger (Dow AgroSci.); Transline (Dow AgroSci.)
Molecular Formula: C6H3Cl2NO2.C2H7NO
Molecular Weight: 253.08
Percent Composition: C 37.97%, H 3.98%, Cl 28.02%, N 11.07%, O 18.97%
Use: Herbicide.
Cloquintocet-Mexyl Cloranolol Clorazepic Acid Clorexolone Cloricromen

Abbreviations 3,6-DCP
CAS number 1702-17-6 YesY
PubChem 15553
ChemSpider 14797 N
KEGG C18779 YesY
Jmol-3D images Image 1
Molecular formula C6H3Cl2NO2
Molar mass 192.00
Appearance White crystalline solid
Melting point 150-152 °C
Solubility in water ~1000 ppm
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

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] 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.[4] It does not affect members of the family Poaceae (grasses).[citation needed]

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 State 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, DowAgro, the manufacturer of clopyralid, voluntarily deregistered it for use on domestic lawns in the US[5] 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.[4]

Clopyralid is licensed for lawn use in France and under the following 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][6] Curtail, Confront, Clopyr AG, Lontrel, Millennium Ultra, Millenium Ultra Plus and Redeem.