1702-17-6

Clopyralid is a pyralid herbicide used to control annual and perennial broadleaf weeds on rangeland, pastures, turf, and lawns, rights-of-way and a few agricultural products such as sugarbeets, oats, barley, mint, and wheat.

If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek Medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek Medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions) if breathing has stopped, and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. Do not induce vomiting when formulations containing petroleum solvents are ingested. Otherwise, give large quantities of water and induce vomiting. Do not make an unconscious person vomit.

UN3077 Environmentally Hazardous substances, solid, n.o.s., Hazard class: 9; Labels: 9-Miscellaneous hazardous material, Technical Name Required

May react violently with strong oxidizers, bromine, 90% hydrogen peroxide, phosphorus trichloride, silver powders, or dust. Incompatible with silver compounds. Mixture with some silver compounds forms explosive salts of silver oxalate. Keep away from oxidizers, sulfuric acid, caustics, ammonia, aliphatic amines, alkanolamines, isocyanates, alkylene oxides, epichlorohydrin. Solutions are strong acids; corrosive to aluminum, iron, and tin. Compounds of the carboxyl group react with all bases, both inorganic and organic (i.e., amines) releasing substantial heat, water, and a salt that may be harmful. Incompatible with arsenic compounds (releases hydrogen cyanide gas), diazo compounds, dithiocarbamates, isocyanates, mercaptans, nitrides, sulfides (releasing heat, toxic, and possibly flammable gases), thiosulfates, and dithionites (releasing hydrogen sulfate and oxides of sulfur).

Clopyralid is an herbicide that selectively inhibits the growth of the broadleaf weed L. palustris over a panel of 17 New Zealand native non-broadleaf plant species when applied at a concentration of 1.5 mg/L. It does not inhibit growth of human pluripotent stem cells (IC₅₀ = >100 μM) or decrease nuclear translocation of the transcription factor SOX17, a marker of teratogenic risk. In vivo, clopyralid induces brain defects in rabbits, but not rats, when administered at a dose of 250 mg/kg.

Odorless and colorless crystalline solid. Odorless. Available as a soluble concentrate that is usually mixed with water. Combustible

White Crystalline Solid

Containers must be disposed of properly by following package label directions or by contacting your local or federal environmental control agency, or by contacting your regional EPA office. Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an Clopyralid 877 afterburner and scrubber. In accordance with 40CFR165, follow recommendations for the disposal of pesticides and pesticide containers.

Systemic post-emergence herbicide for use in food crops and mesquite.

ChEBI: An organochlorine pesticide having a 3,6-dichlorinated picolinic acid structure.

Herbicide: Clopyralid is used to control annual and perennial broadleaf weeds on rangeland, pastures, turf and lawns, rights-of-way and a few agricultural products such as sugar beets, oats, barley, mint and wheat.

ACCENT®; CONFRONT®; CURTAIL®; CURTAIL M®; DOWCO®-290; HORNET®; LONTREL®; LONTREL® 3; LONTRIL® F; LONTRIL® T; MATRIGON®; MILLENNIUM®; NAF®-280; PARADIGM®; RECLAIM®; REDEEM®; RIVERDALE®; SCORPION®; STINGER®; TRANSLINE®; WIDEMATCH®; XRM-3972®

Selective, systemic, absorbed through leaves and roots. Synthetic auxin.

Clopyralid is systemic herbicides that is actively absorbed by foliage and, is also readily absorbed through root tissues. Once absorbed, it is translocated, primarily in the phloem, throughout the entire plant. At normal field doses, this herbicide controls many broadleaf species and are selective in pasturelands and most grass crops. The exact weed spectrum and use is specific to the compound.

General procedure for the synthesis of 3,6-dichloro-2-pyridinecarbonic acid from 3,6-dichloro-2-cyanopyridine: 21.6 g (0.1 mol) of 2-cyano-3,6-dichloro pyridine wet product (moisture content: 20.1 wt%) prepared in step 3 was suspended in 60 g of ethanol, and 8.4 g (0.21 mol) of sodium hydroxide was added to the system. The reaction mixture was heated to reflux to ensure that the reaction proceeded adequately. The progress of the reaction was monitored by liquid chromatography (HPLC) during the reaction. After completion of the reaction, the reaction mixture was cooled and some ethanol was removed by distillation under reduced pressure. The product was diluted by adding 30 g of water and the pH was adjusted to 2-3 with dilute hydrochloric acid to promote crystallization of the product. The mixture was stirred to allow complete crystallization followed by filtration and the solid was washed well with cold water. The resulting solid was dried under suitable conditions to give 18.2 g of the target product 3,6-dichloro-2-pyridinecarboxylic acid in 94.8% yield.

Clopyralid is a relatively strong acid and water soluble, making it susceptible to leaching. Most studies, however, indicate that it is metabolized relatively quickly by soilmicrobes, significantly decreasing the amount of clopyralid that is available for this process. Clopyralid is dissociated in soil because of its low pKa, and thus, its adsorption to most soils is weak and governed by the anion exchange capacity. Soils with relatively large anion exchange capacities will bind relatively large quantities of clopyralid,making it biologically unavailable. Clopyralid is not volatile.

Chemical. Clopyralid is stable to hydrolytic decomposition in acidic conditions becoming unstable above pH 5. It does not undergo significant photolytic degradation. Clopyralid decomposes above its melting point.
Plant. Hall and Vanden Born (29) showed that clopyralid underwent substantial metabolism in tolerant Brasica napus; i.e., 70% of applied clopyralid was metabolized 144 hours after application. Themetabolites were not fully characterized. Relatively little metabolism is thought to occur in susceptible plants.
Soil. Clopyralid is readily degraded by soil microbes, e.g., the field dissipation DT₅₀ ranges from 8 to 66 days. The major metabolic pathway in soil microbes is decarboxylation.

Mammalian Toxicity. Limited studies have been conducted, but, from what data exist, it appears that clopyralid is quickly excreted, unmodified, in the urine of animals. The acute oral LD₅₀ of clopyralid in male and female rat is 3738 mg/kg and 2775 mg/kg, respectively.
Weed Resistance/Modified Crop Tolerance. Fuerst et al. (48) reported clopyralid resistance in yellow starthistle (Centaurea solstitialis). No crops with modified tolerance toward clopyralid are currently in production.

The Initial Threshold Screening Level (ITSL) for Clopyralid is 500 μg/m3 with an annual averaging time.

[1] Patent: CN106243027, 2016, A. Location in patent: Paragraph 0011; 0032; 0033
[2] Patent: US6610853, 2003, B1

Herbicide