5-(2-chloro-a,a,a-trifluoro-p-tolyloxy)-2-nitrobenzoic acid

5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid

C₁₄H₇ClF₃NO₅

Light brown solid.

142-160℃

<0.01 mPa

1.546

In water 120 mg/l (23-25 ℃) (tech.). In acetone 600, ethanol 500, dichloromethane 50, xylene, kerosene <10 (all in g/kg, 25 ℃)

Decomposes at 235 ℃. Stable in acid and alkaline media, pH 3-9 (40 ℃). Decomposed by u.v. light, DT50 c. 110 h

Protoporphyrinogen oxidase inhibitor.

Selective contact herbicide, absorbed by the foliage and roots, with negligible translocation. Activity is enhanced by sunlight.

Used post-emergence for the control of annual broad-leaved weeds (Abutilon, Amaranthus, Datura, Euphorbia, Polygonum, Ipomoea, Xanthium spp.), with some effects on grasses in soya beans, peanuts and rice. Applied at 0.2 to 0.6 kg/ha, depending on crop.

Soya beans show good tolerance, although some burning may be seen on new leaf growth, which is readily outgrown. Phytotoxicity increased if mixed with fertilisers.

Compatible with most other pesticides, but phytotoxicity to the crop may be increased with the addition of certain additives.

Acute oral LD₅₀ for rats 1540, female mice 1370, rabbits 1590 mg/kg b.w. (aqueous tech.).

Acute percutaneous LD₅₀ for rabbits >2000 mg/kg. Severe eye irritant; moderate skin irritant (rabbits) (aqueous tech.).

LC₅₀ (4 h) for rats >6.91 mg/l air (aqueous formulation).

for mice 7.5 ppm (mg/kg diet) (aqueous tech.).

10 mg/kg.

WHO (a.i.) III; EPA (formulation) III

Acute oral LD₅₀ for bobwhite quail 325 mg/kg. LC₅₀ (8 d) for bobwhite quail and mallard ducks >5620 mg/kg diet.

LC₅₀ (96 h) for rainbow trout 17, bluegill sunfish 62 mg/l.

EC₅₀ (48 h) 77 mg/l.

EC₅₀ for Selenastrum capricornutum >260, Anabaena flos-aquae >350 ug/l.

LC₅₀ (14 d) for Eisenia foetida >1800 mg/kg substrate.

Not transported within the plant; degradation occurs at, or close to, the surface, DT₅₀ c. 1 w. Metabolism is fast and extensive, through amination, hydroxylation and carboxylation.

After oral application in rats, a fast and almost complete absorption and excretion occurs. Multiple application does not indicate a cumulative effect. The dermal resorption is low. Acifluorfen-sodium is judged not to present a substantial hazard to aquatic or terrestrial wildlife.

The a.i. will be moderately quickly degraded, DT₅₀ 108 d (silt loam) - 200 d (clay loam), forming mainly bound residues and highly polar metabolites. Degradation occurs through microbial activity; there is also photolytic degradation on the soil surface. Accumulation in soil does not occur. Adsorption Koc 44-684, Kd 0.13-1.98; desorption Koc 131-1955, Kd 0.39-4.6. In water, acifluorfen is hydrolytically stable in the dark, but in light it is rapidly degraded, DT₅₀ c. 2 h, forming mainly CO₂.

analysis by hplc. Residue analysis by glc or hplc.