Triclopyr

Triclopyr[1]
IUPAC name [(3,5,6-Trichloro-2-pyridinyl)oxy]acetic acid
Identifiers
CAS number	55335-06-3 Y
	UNII	MV06PHJ6I0 Y
Jmol-3D images	Image 1
SMILES ClC1=C(OCC(O)=O)N=C(Cl)C(Cl)=C1
InChI InChI=1/C7H4Cl3NO3/c8-3-1-4(9)7(11-6(3)10)14-2-5(12)13/h1H,2H2,(H,12,13)
Properties
Molecular formula	C7H4Cl3NO3
Molar mass	256.46
Appearance	Fluffy solid
Melting point	148-150 °C
Solubility in water	440 mg/L
Solubility in acetone	989 g/kg
Acidity (pKa)	2.68
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Triclopyr (3,5,6-Trichloro-2-pyridinyloxyacetic acid) is a systemic, foliar herbicide in the pyridine group. It is used to control broadleaf weeds while leaving grasses and conifers unaffected.

Triclopyr is unusually effective on woody plants and is used for brush control in rights of way and defoliation of wooded areas. It is sold under the trade names Garlon and Release for these purposes.

Also used for broadleaf weeds, particularly Creeping Charlie (Glechoma hederacea), upon which it is uncommonly effective. 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 It is a major ingredient in Confront, which was withdrawn from most uses due to concerns about compost contamination from the other major ingredient, clopyralid. In the UK it is sold as SBK, Shrub and Brushwood Killer.

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).^[2] It has been found non-toxic to bees and very slightly toxic to fish (Rainbow trout LC₅₀ (96 hrs.) = 117 ppm).^[3]

References

1. ↑ Merck Index, 11th Edition, 9572.
2. ↑ EXTOXNET (Extension Toxicology Network), Oregon State University
3. ↑ Environmental Fate Of Triclopyr, Carissa Ganapathy, Environmental Monitoring & Pest Management Branch Department of Pesticide Regulation Sacramento, CA

External links

• Triclopyr Technical Fact Sheet - National Pesticide Information Center
• Triclopyr General Fact Sheet - National Pesticide Information Center
• Triclopyr Pesticide Information Profile - Extension Toxicology Network