Acaricide
pyrazole (acaricide)



NOMENCLATURE
Common name tebufenpyrad (BSI, draft ISO)
IUPAC name N-(4-tert-butylbenzyl)-4-chloro-3-ethyl-1-methylpyrazole-5-carboxamide 
Chemical Abstracts name 4-chloro-N[[4-(1,1-dimethylethyl)phenyl]methyl]-3-ethyl-1-methyl-1H-pyrazole-5-carboxamide 
CAS RN [119168-77-3]  Development codes AC 801757 (Cyanamid); MK-239 (Mitsubishi Kasei)

PHYSICAL CHEMISTRY
Mol. wt. 333.9  M.f. C₁₈H₂₄ClN₃O  Form Colourless crystals.  M.p. 61-62 ºC  V.p. <1 ´ 10^-2 mPa (25 ºC)  K_OW logP = 5.04 (25 ºC)  Henry <1.25 ´ 10^-3 Pa m³ mol^-1 (calc.)  S.g./density 1.0214  Solubility In water 2.8 mg/l (25 ºC). Soluble in acetone, methanol, chloroform, acetonitrile, hexane, and benzene.  Stability Stable to hydrolysis, DT₅₀ >28 d (pH 5, 7 and 9).

APPLICATIONS
Biochemistry Mitochondrial respiration inhibitor. Acts as an inhibitor of the electron transport chain at Site I. Does not act as a specific muscle or nerve poison.  Mode of action Non-systemic acaricide active by contact and ingestion. Exhibits translaminar movement following application to leaves, and thus inhibits the development of mite eggs oviposited on the undersides of leaves.  Uses Control of all stages of Tetranychus, Panonychus, Oligonychus, and Eotetranychus spp. on top fruit, vines, citrus, vegetables, hops, ornamentals, melons, and cotton. Applied at 50-200 g/ha.  Formulation types EC; EW; WG; WP.

ANALYSIS
Details from Mitsubishi.

MAMMALIAN TOXICOLOGY
Oral Acute oral LD₅₀ for male rats 595, female rats 997, male mice 224, female mice 210 mg/kg.  Skin and eye Acute percutaneous LD₅₀ for rats >2000 mg/kg. Non-irritating to skin; slightly irritating to eyes (rabbits). Not a skin sensitiser (guinea pigs).  Inhalation LC₅₀ for male rats 2660, female rats >3090 mg/m³.  Other No mutagenic effects were observed in the following tests; Ames, mammalian micronucleus, Drosophila wing spot, in vitro cultured human lymphocytes, in vivo bone marrow erythrocytes, unscheduled DNA synthesis, and CHO/HGPRT.  Toxicity class WHO (a.i.) III  EC hazard (Xn; R20/22)

ECOTOXICOLOGY
Birds Acute oral LD₅₀ for mallard ducks >2000 mg/kg. Dietary LC₅₀ (8 d) for mallard ducks and bobwhite quail >5000 mg/kg diet.  Fish LC₅₀ (48 h) for carp 0.073 mg/l.  Daphnia LC₅₀ (3 h) 1.2 mg/l.  Bees Low toxicity to honeybees. 

ENVIRONMENTAL FATE
Animals Metabolite is N-[4-(1-hydroxymethyl-1-methylethyl)benzyl]-4-chloro-3-(1- hydroxyethyl)-1-methylpyrazole-5-carboxamide.  Plants As for animals.  Soil/Environment Aerobic degradation occurs in soil, DT₅₀ 20-30 d. K_oc 1380-4930.