Chemical Properties
White to Off-White Solid
Uses
Selective postemergence herbicide to control many woody and broad-leaved weeds.
Uses
Triclopyr is a selective post-emergence herbicide.
Definition
ChEBI: A monocarboxylic acid that is (pyridin-2-yloxy)acetic acid substituted by chloro groups at positions 3, 5 and 6. It is an agrochemical used as a herbicide.
Agricultural Uses
Herbicide: Triclopry is a systemic herbicide used on rice, range
land and pasture, rights-of-way, forestry and grasslands,
including home lawns, for control of broadleaf weeds and
woody plants. Triclopry is usually available as a triclopyr
butoxyethyl ester (BEE) or as a triclopry triethylamine
salt (TEA). Registered for use in the U.S. Some products
may be classified as Restricted Use Pesticides (RUP).
Registered for use in EU countries
.
U.S. Maximum Allowable Residue Levels for Triclopyr
and its metabolites 3,5,6,-trichloro-2-pyridinol and
2-methoxy-3,5,6-trichloropyridine [40 CFR 180.417
(a)(1)]: for the combined residues of the herbicide in
or on the following raw agricultural commodities: fish
3.0 ppm; grass, forage 500 ppm; grass, forage, hay
500 ppm;shellfish3.5 ppm.[40 CFR 180.417 (a)(2)]:
in or on the following agricultural commodities: egg
0.05 ppm; meat, fat, and meat byproducts, except kidney
and liver, of cattle, goat, hog, horse and sheep 0.05 ppm;
meat, fat, and meat byproducts, except kidney, of poultry
0.1 ppm; milk 0.01 ppm; liver and kidney of cattle, goat,
hog, horse and sheep 0.5 ppm; rice, grain 0.3 ppm; rice,
straw10.0 ppm.
Trade name
[Note: See the following record, Triclopyr,
triethylamine salt, for trade names containing the salt of
triclopry] ACCESS®; CROSSBOW®, (triclopyr + 2,4-D
ester); ET®; GARLON®; GRAZON® Triclopyr;
PATHFINDER®; REDEEM®; RELY®; REMEDY®;
RIVERDALE TAHOE® Nufarm (Australia); TURFLON®
Mechanism of action
Selective, systemic, absorbed through roots and foliage. Synthetic auxin.
Safety Profile
Moderately toxic by ingestion. Anexperimental teratogen. Experimental reproductiveeffects. Used as an herbicide. When heated todecomposition it emits toxic fumes of Clí and NOx.
Synthesis
The general procedure for the synthesis of 2-((3,5,6-trichloropyridin-2-yl)oxy)acetic acid from the compound (CAS: 60825-27-6) is as follows: in a reactor equipped with a mechanical stirrer, a thermometer casing, and a reflux condenser, 0.404 mol of trichloromethyl ethyl ester was added. Subsequently, an appropriate amount of water was added to prepare a 10% aqueous slurry. Next, 19.42 g (0.485 moles) of sodium hydroxide (NaOH) was added. The slurry was heated to 80°C and the reaction was maintained at this temperature for 3.5 hours. Upon completion of the reaction, the reaction mixture was cooled to room temperature. Then, 115 ml of 4% sodium hypochlorite (NaOCl) solution was added and the mixture was stirred for 30 minutes. After that, the reaction mixture was acidified with sulfuric acid to a pH of 1-2, at which point a white precipitate was produced. The precipitate was filtered and dried to give the final target product 2-((3,5,6-trichloropyridin-2-yl)oxy)acetic acid in 93% yield.
Environmental Fate
Soil. In soil, triclopyr degraded to 3,5,6-trichloro-2-pyridinol and 2-methoxy-3,5,6-
trichloropyridine (Norris et al., 1987). The major route of dissipation from soil is likely
due to microbial degradation (Newton et al., 1990).
Fifty-four days after triclopyr was applied to soil at a rate of 5.6 kg/ha, the majority
(65%) remained in the top 10 cm of soil (Lee et al., 1986a).
Ashton and Monaco (1991) reported triclopyr had an average half-life of 46 days and
is in?uenced by soil type and climatic conditions.
Plant. Lewer and Owen (1989) found 3,5,6-trichloro-2-pyridinol as the major metab-
olite in plants. Cultured soybean cells metabolized triclopyr to dimethyl triclopyr-aspartate
and dimethyl triclopyr-glutamate which can be rehydrolyzed to form the parent compound.
At an application rate of 3.4 kg/ha, the dissipation half-life was 3.7 days. At an
application rate of 3.3 kg/ka, the dissipation half-lives of triclopyr in brown, browse and
litter samples were 73.5, 202.3 and 31 days, respectively (Norris et al., 1987).
Metabolic pathway
After 7 days in a soybean cell suspension culture, the
major metabolites of trichlopyr are formed and
identified as the aspartate (major) and glutamate
(minor) amide conjugates.
Metabolism
The average half-life of triclopyr
in soil is 46 days. Because triclopyr is sensitive to light,
the length of time that it remains on the surface may
moderate its persistence. Adsorption to soil is limited and
is governed by the anion exchange capacity. Insignificant
amounts are lost via volatilization. The propensity of
triclopyr to translocate in the environment with soil water,
is unknown.
Toxicity evaluation
The acute oral LD50 of triclopyr
is 692 mg/kg and 577 mg/kg for male and female rat,
respectively. It does not appear to undergo significant
transformation and is excreted in the urine primarily
unchanged.
References
[1] Patent: WO2010/23679, 2010, A2. Location in patent: Page/Page column 9; 10
[2] Patent: EP3210992, 2017, A1. Location in patent: Paragraph 0066; 0068
[3] Patent: CN102718700, 2016, B. Location in patent: Paragraph 0065-0067
