Chlorfenapyr

IRAC 13  arylpyrrole

 

NOMENCLATURE
Common name chlorfénapyr ((m) F-ISO); chlorfenapyr (BSI, E-ISO, ANSI)  IUPAC name 4-bromo-2-(4-chlorophenyl)-1-ethoxymethyl-5-trifluoromethylpyrrole-3-carbonitrile
Chemical Abstracts name 4-bromo-2-(4-chlorophenyl)-1-(ethoxymethyl)-5-(trifluoromethyl)-1H-pyrrole-3-carbonitrile  CAS RN [122453–73–0]  Smiles code CCOCn1c(c(C#N)c(Br)c1C(F)(F)F)c2ccc(Cl)cc2

PHYSICAL CHEMISTRY
Mol. wt. 407.6 M.f. C₁₅H₁₁BrClF₃N₂O  Form White solid.  M.p. 101–102 °C  V.p. <1.2 × 10^-2 mPa (20 °C) K_ow logP = 4.83 S.g./density 0.355 (24 °C) Solubility In water 0.14 mg/l (pH 7, 25 °C). In hexane 0.89, methanol 7.09, acetonitrile 68.4, toluene 75.4, acetone 114, dichloromethane 141 (all in g/100 ml, 25 °C). (EPA Fact Sheet). Stability In air, DT₅₀ 0.88 d (10.6 h, calc.). In water (direct photodegradation), DT₅₀ 4.8–7.5 d. Stable to hydrolysis (pH 4, 7 and 9).

APPLICATIONS
Biochemistry Oxidative removal in vivo of the N-ethoxymethyl group generates the active species, which is a mitochondrial uncoupler.

Mode of action Insecticide and acaricide with mainly stomach and some contact action. Exhibits good translaminar, but limited systemic, activity in plants.

Uses Control of many species of insects and mites, including those resistant to carbamate, organophosphate and pyrethroid insecticides and also chitin-synthesis inhibitors, in cotton, vegetables, citrus, top fruit, vines and soya beans. Among pests resistant to conventional products which are controlled by chlorfenapyr are Brevipalpus phoenicis (leprosis mite), Leptinotarsa decemlineata (Colorado potato beetle), Helicoverpa spp., Heliothis spp., Plutella xylostella (diamond-back moth) and Tetranychus spp. Also control of many species of structural and household Formicidae (especially Camponotus, Iridomyrmex, Monomorium and Solenopsis spp.), Blattellidae (especially Blatta, Blattella, Periplaneta and Supella spp.), Kalotermitidae (especially Incisitermes spp.) and Rhinotermitidae (especially Reticulitermes, Coptotermes and Heterotermes spp.), at use rates of between 0.125% and 0.50% a.i. w/w. Phytotoxicity No phytotoxicity observed at field use rates.

Formulation types EC; SC.

ANALYSIS
Product by glc. Residues by hplc. Details from BASF.

ENVIRONMENTAL FATE
Animals In rats, >60% of orally administered chlorfenapyr was excreted, primarily through faeces, within 24 hours. The absorbed residues were metabolised via N-dealkylation, dehalogenation, hydroxylation and conjugation. Parent and less polar metabolites were found in egg, milk and tissues such as fat and liver. Metabolism in hens and goats is similar to that in rats, however, in these species, 80% of orally administered chlorfenapyr was rapidly excreted. Unexcreted residues were present in kidney and liver. At the potential maximum dietary burden, all residues are <0.01 ppm. Chlorfenapyr is the only significant residue component. Plants In cotton, citrus, tomato, lettuce and potato, chlorfenapyr is dealkylated to the insecticidally active component (AC 303268) or debrominated to less toxic metabolites. Chlorfenapyr does not translocate out of treated plant parts. Parent compound is the prominent residue. Soil/Environment In soil, chlorfenapyr is the major residue. Debromination to a less toxic metabolite is the primary route of degradation; dealkylation is not a primary route of degradation in soil. K_oc >10 000 ml/g, indicating chlorfenapyr is likely to be strongly bound in soils. In water, DT₅₀ (direct photodegradation) 4.8–7.5 d; stable to hydrolysis at pH 4, 7 and 9.

TOXICOLOGICAL & ENVIRONMENTAL REVIEWS
EPA Fact Sheet, Jan. 2001. EU Status (1107/2009) Not approved, 2001/697/EC.

MAMMALIAN TOXICOLOGY
Oral Acute oral LD₅₀ for male rats 441, female rats 1152, male mice 45, female mice 78 mg tech./kg (EPA Fact Sheet). Skin and eye Acute percutaneous LD₅₀ for rabbits >2000 mg/kg. Moderate eye irritant; non-irritating to skin (rabbits). Inhalation LC₅₀ for rats 1.9 mg tech./l air. NOEL Chronic oral toxicity and carcinogenicity NOAEL (80 w) for male mice 2.8 mg/kg daily (20 ppm); dietary neurotoxicity NOAEL (52 w) for rats 2.6 mg/kg daily (60 ppm) (EPA Fact Sheet). ADI (ECCO) 0.015 mg/kg b.w. [1999]; (EPA) RfD 0.003 mg/kg [1997]. Other Non-mutagenic in the Ames, CHO/HGPRT, mouse micronucleus and unscheduled DNA synthesis tests. Toxicity class WHO (a.i.) II EPA (formulation) III (240 g/l ‘Pylon’, ‘Phantom’) EC classification T; R23| Xn; R22| N; R50, R53| concn. dep.

ECOTOXICOLOGY
Birds Acute oral LD₅₀ for mallard ducks 10, bobwhite quail 34 mg/kg. LC₅₀ (8 d) for mallard ducks 9.4, bobwhite quail 132 ppm. Fish LC₅₀ (48 h) for carp 500 μg/l. LC₅₀ (96 h) for rainbow trout 7.44, bluegill sunfish 11.6 μ;g/l. Daphnia LC₅₀ (96 h) 6.11 μg/l. Algae EC₅₀ for Selenastrum capricornutum 132 ppb. Bees LD₅₀ 0.2 μg/bee. Worms NOEC (14 d) for Eisenia foetida 8.4 mg/kg.