Fenoxaprop-P-Ethyl

NOMENCLATURE
fenoxaprop-P-ethyl
Chemical Abstracts name: ethyl (R)-2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy]propanoate
CAS RN: [71283-80-2]

fenoxaprop-P
Common name: fenoxaprop-P
IUPAC name: (R)-2-[4-(6-chloro-1,3-benzoxazol-2-yloxy)phenoxy]propionic acid; (R)-2-[4-(6-chlorobenzoxazol-2-yloxy)phenoxy]propionic acid
Chemical Abstracts name: (R)-2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy]propanoic acid
CAS RN: [113158-40-0]

PHYSICAL CHEMISTRY
fenoxaprop-P-ethyl
Mol. wt.: 361.8; M.f.: C₁₈H₁₆ClNO₅ Form: White, odourless solid. M.p.: 89-91 ^oC. V.p.: 5.3x10^-4 mPa (20 ^oC). KOW: logP = 4.58. Henry: 2.74x10^-4 Pa m³ mol^-1 (calc.) S.g./density: 1.3 (20 ^oC). Solubility: In water 0.7 mg/l (pH 5.8, 20 ^oC). In acetone 200, toluene 200, ethyl acetate >200, ethanol c. 24 (all in g/l, 20 ^oC). Stability: Fenoxaprop-P-ethyl is stable for 90 d at 50 ^oC. Not sensitive to light. Decomposed by acids and alkalis, DT₅₀ >1000 d (pH 5), 100 d (pH 7), 2.4 d (pH 9) (20 ^oC).

fenoxaprop-P
Mol. wt.: 333.7; M.f.: C₁₆H₁₂ClNO₅ Form: Light beige, weakly pungent, fine powder. M.p.: 155-161 C; V.p.: 1.8x10^-1 mPa (20 ^oC). KOW: logP = 1.83-0.24 (pH 5 - pH 9). S.g./density: c. 1.5 (20 ^oC) Solubility: In water 0.27 (pH 5.1), 61 (pH 7.0) (both in g/l, 20 ^oC). In acetone 80, toluene 0.5, ethyl acetate 36, methanol 34 (all in g/l, 20 ^oC).

APPLICATIONS
fenoxaprop-P-ethyl
Biochemistry: Fatty acid synthesis inhibition in grasses, by inhibition of acetyl CoA carboxylase (ACCase).
Mode of action: Fenoxaprop-P-ethyl is a selective herbicide with contact and systemic action, absorbed principally by the leaves, with translocation both acropetally and basipetally to the roots or rhizomes.
Uses: Post-emergence control of annual and perennial grass weeds in potatoes, beans, soya beans, beets, vegetables, peanuts, flax, oilseed rape, and cotton; and (when applied with the herbicide safener mefenpyr-diethyl) annual and perennial grass weeds and wild oats in wheat, rye, triticale and, depending on ratio, in some varieties of barley.
Phytotoxicity: Non-phytotoxic to broad-leaved crops.
Formulation types: EC; EW; SE.

MAMMALIAN TOXICOLOGY
fenoxaprop-P-ethyl
Oral: Acute oral LD₅₀ for rats 3150-4000, mice >5000 mg/kg.
Skin and eye: Acute percutaneous LD₅₀ for rats >2000 mg/kg.
Inhalation: LC₅₀ (4 h) for rats >1.224 mg/l air.
NOEL: (90 d) for rats 0.75 mg/kg b.w. daily (10 ppm), mice 1.4 mg/kg b.w. daily (10 ppm), dogs 15.9 mg/kg b.w. daily (400 ppm).

ECOTOXICOLOGY
fenoxaprop-P-ethyl
Birds: Acute oral LD₅₀ for bobwhite quail >2000 mg/kg.
Fish: LC₅₀ (96 h) for bluegill sunfish 0.58, rainbow trout 0.46 mg/l.
Daphnia: LC₅₀ (48 h) 0.56 (pH 8.0-8.4), 2.7 (pH 7.7-7.8) (both mg/l).
Algae: LC₅₀ (72 h) for Scenedesmus subspicatus 0.51 mg/l.
Bees: LC50 (contact) >300 ug/bee; (feed) >1000 ug/bee.
Worms: LC₅₀ (14 d) for Eisenia foetida >1000 mg/kg soil.

ENVIRONMENTAL FATE
Plants: In plants, fenoxaprop-ethyl is metabolised via fenoxaprop to 6-chloro-2,3-dihydrobenzoxazol-2-one.
Soil/Environment: In soil, fenoxaprop-ethyl is rapidly hydrolysed to fenoxaprop; DT₅₀ 1-10 d.