Triclopyr

Triclopyr^[1]

Names
IUPAC name [(3,5,6-Trichloro-2-pyridinyl)oxy]acetic acid
Other names Trident (Agriphar)
Identifiers
CAS Number	55335-06-3
3D model (Jmol)	Interactive image Interactive image
ChEBI	CHEBI:9682
ChemSpider	37801
ECHA InfoCard	100.054.161
PubChem	41428
UNII	MV06PHJ6I0
InChI InChI=1S/C7H4Cl3NO3/c8-3-1-4(9)7(11-6(3)10)14-2-5(12)13/h1H,2H2,(H,12,13) Key: REEQLXCGVXDJSQ-UHFFFAOYSA-N InChI=1/C7H4Cl3NO3/c8-3-1-4(9)7(11-6(3)10)14-2-5(12)13/h1H,2H2,(H,12,13) Key: REEQLXCGVXDJSQ-UHFFFAOYAE
SMILES ClC1=C(OCC(O)=O)N=C(Cl)C(Cl)=C1 C1=C(C(=NC(=C1Cl)Cl)OCC(=O)O)Cl
Properties
Chemical formula	C7H4Cl3NO3
Molar mass	256.46
Appearance	Fluffy solid
Melting point	148 to 150 °C (298 to 302 °F; 421 to 423 K)
Solubility in water	440 mg/L
Solubility in acetone	989 g/kg
Acidity (pKa)	2.68
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Triclopyr (3,5,6-Trichloro-2-pyridinyloxyacetic acid) is an organic compound in the pyridine group that is used as a systemic, foliar herbicide^[2] and fungicide.^[3]

Uses

Triclopyr is used to control broadleaf weeds while leaving grasses and conifers unaffected^[2] or to control rust diseases on crops.^[3]

Triclopyr is effective on woody plants and is used for brush control in rights of way and defoliation of wooded areas. In the USA it is sold under the trade names Garlon and Release, and in the UK as SBK Brushwood Killer.

It is also used for broadleaf weeds, particularly Creeping Charlie (Glechoma hederacea). It is sold under the trade names Turflon, Weed-B-Gon (purple label), and Brush-B-Gon ("Poison Ivy Killer") for these purposes. It is a major ingredient in Confront, which was withdrawn from most uses due to concerns about compost contamination from the other major ingredient, clopyralid.

Triclopyr is formulated both as an ester and as an amine salt. The usual tradeoffs regarding effectiveness, drift, and toxicity to humans apply to these two formulations. It is chemically very similar to the herbicide which it generally replaces, 2,4,5-T, which was phased out in the U.S. in the 1970s amid toxicity concerns.

Environmental issues

Triclopyr breaks down in soil with a half-life of between 30 and 90 days. One of the byproducts of breakdown, trichloropyridinol, remains in the soil for up to a year. Triclopyr degrades rapidly in water. It remains active in decaying vegetation for about 3 months.

The compound is slightly toxic to ducks (LD₅₀ = 1698 mg/kg) and quail (LD₅₀ = 3000 mg/kg).^[4] It has been found non-toxic to bees and very slightly toxic to fish (Rainbow trout LC₅₀ (96 hrs.) = 117 ppm).^[5]

References

1. Merck Index, 11th Edition, 9572.
2. Appleby, Arnold P.; Müller, Franz; Carpy, Serge (2001). "Weed Control". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a28_165.
3. Shanmugasundaram, S.; Yeh, C.C.; Hartman, G.L.; Talekar, N.S. (1991). Vegetable Soybean Research Needs for Production and Quality Improvement (PDF). Taipei: Asian Vegetable Research and Development Center. pp. 86–87. ISBN 9789290580478. Retrieved 6 February 2016.
4. EXTOXNET (Extension Toxicology Network), Oregon State University
5. Environmental Fate Of Triclopyr, Carissa Ganapathy, Environmental Monitoring & Pest Management Branch Department of Pesticide Regulation Sacramento, CA

External links

• archived Triclopyr Technical Fact Sheet - National Pesticide Information Center
• Triclopyr General Fact Sheet - National Pesticide Information Center
• Triclopyr Pesticide Information Profile - Extension Toxicology Network
• Triclopyr in the Pesticide Properties DataBase (PPDB)