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Imazethapyr (443)

Imazethapyr 95%TC

Imazethapyr 70%WP

Imazethapyr 10%SL

Herbicide

HRAC B WSSA 2; imidazolinone

 

 

NOMENCLATURE

imazethapyr

Common nameimazethapyr (BSI, ANSI, draft E-ISO, (m) draft F-ISO)

IUPAC name(RS)-5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid

Chemical Abstracts name(?-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-ethyl-3-pyridinecarboxylic acid

CAS RN[81335-77-5]Development codesAC 263 499; CL 263 499 (both Cyanamid)

PHYSICAL CHEMISTRY

imazethapyr

Mol. wt.289.3M.f.C15H19N3O3FormColourless crystals.M.p.169-173 ºCB.p.Decomp. 180 °CV.p.<0.013 mPa (60 ºC)KOWlogP = 1.04 (pH 5), 1.49 (pH 7), 1.20 (pH 9) (all 25 ºC)S.g./density1.10-1.12 (21 °C)SolubilityIn water 1.4 g/l (25 ºC). In acetone 48.2, methanol 105, toluene 5, dichloromethane 185, dimethyl sulfoxide 422, isopropanol 17, heptane 0.9 (all in g/l, 25 ºC).StabilityRapidly degraded in sunlight, DT50c. 3 d.pKapKa12.1, pKa23.9

imazethapyr-ammonium

Mol. wt.306.4M.f.C15H22N4O3

COMMERCIALISATION

HistoryHerbicide reported by T. Malefyt et al. (Abstr. 1984 Weed Sci. Soc. Mtg., Miami, p. 18, Abstract 49). Introduced by American Cyanamid Co. (now BASF AG).PatentsUS 4798619ManufacturersBASF

Imazethapyr APPLICATIONS

BiochemistryBranched chain amino acid synthesis (ALS or AHAS) inhibitor. Hence reduces levels of valine, leucine and isoleucine, leading to disruption of protein and DNA synthesis. Selectivity in soya benas and peanuts is attributed to rapid detoxification via hydroxylation and glycosylation (B. Tecle et al., Proc. 1997 Br. Crop Prot. Conf. - Weeds,1, 605).Mode of actionSystemic herbicide, absorbed by the roots and foliage, with translocation in the xylem and phloem, and accumulation in the meristematic regions.UsesControl of many major annual and perennial grass and broad-leaved weeds in soya beans and other leguminous crops. Applied pre-plant incorporated, pre-emergence, or post-emergence.PhytotoxicityNon-phytotoxic to soya beans and other leguminous crops, when used as directed.Formulation typesSL.Selected tradenames:'Hammer' (ammonium salt) (BASF); 'Overtop' (ammonium salt) (BASF); 'Pivot' (ammonium salt) (BASF); 'Pursuit DG' (acid) (BASF); 'Pursuit' (ammonium salt) (BASF)

Imazethapyr OTHER TRADENAMES

imazethapyr

'Wayup' (BASF); 'Vezir' (Herbitécnica) mixtures:'Clean Sweep' (+ bentazone) (BASF); 'Elite' (+ pendimethalin) (BASF); 'Lightning' (+ imazapyr) (BASF); 'Odyssey' (+ imazamox) (Canada) (BASF); 'Pursuit Plus' (+ pendimethalin) (acid) (BASF); 'Steel' (+ imazaquin+ pendimethalin) (BASF) Discontinued names:'Event' * (Cyanamid); 'ImPede' * (Cyanamid) mixtures:'Passport' * (+ trifluralin) (Cyanamid); 'Resolve' * (+ dicamba) (Cyanamid)

imazethapyr-ammonium

Discontinued names mixtures:'Contour' * (+ atrazine) (Cyanamid)

Imazethapyr MAMMALIAN TOXICOLOGY

OralAcute oral LD50for male and female rats, and female mice >5000 mg/kg.Skin and eyeAcute percutaneous LD50for rabbits >2000 mg/kg; mild skin and reversible eye irritant.InhalationLC50for rats 3.27 mg/l air (analytical), 4.21 mg/l (gravimetric).NOEL(2 y) for rats >10 000 mg/kg diet; (1 y) for dogs >10000 mg/kg diet (highest dose tested).OtherNon-mutagenic in the Ames test.Toxicity classWHO (a.i.) III (Table 5); EPA (formulation) III

Imazethapyr ECOTOXICOLOGY

imazethapyr

BirdsAcute oral LD50for bobwhite quail and mallard ducks >2150 mg/kg.FishLC50(96 h) for bluegill sunfish 420, rainbow trout 340, channel catfish 240 mg/l.DaphniaLC50(48 h) <1000 mg/l.AlgaeNOEL for Selenastrum capricornutum 50 mg/l.Other aquatic spp.I50for Lemna gibba 4.38 mg/l.BeesTopical LD50for honeybees >0.1 mg/bee.WormsI50>10 000 mg/kg.