Herbicide, fungicide

NOMENCLATURE

difenzoquat metilsulfate

Common name difenzoquat metilsulfate

CAS RN [43222-48-6]  EEC no. 256-152-5  Development codes AC 84 777 ; CL 84 777 (both Cyanamid) 

difenzoquat

Common name difenzoquat (BSI, E-ISO, (m) F-ISO, ANSI, WSSA)

IUPAC name 1,2-dimethyl-3,5-diphenylpyrazolium 

Chemical Abstracts name 1,2-dimethyl-3,5-diphenyl-1H-pyrazolium 

CAS RN [49866-87-7] 

PHYSICAL CHEMISTRY

difenzoquat metilsulfate

Composition Tech. grade is 96% pure.  Mol. wt. 360.4  M.f. C18H20N2O4S  Form Colourless, hygroscopic crystals.  M.p. 150-160 ºC (tech.)  V.p. <1 ´ 10-2 mPa  KOW logP = 0.648 (pH 5), -0.62 (pH 7), -0.32 (pH 9)  S.g./density 0.8 (25 °C)  Solubility In water 765 g/l (25 ºC). In dichloromethane 360, chloroform 500, methanol 588, 1,2-dichloroethane 71, isopropanol 23, acetone 9.8, xylene, heptane <0.01 (all in g/l, 25 ºC). Slightly soluble in petroleum ether, benzene, and dioxane.  Stability Stable to light in aqueous media. Thermally stable. Stable in weakly acidic media, but decomposed by strong acids and oxidants.  pKa c. 7  F.p. >82 °C (Tag open cup) 

difenzoquat

Mol. wt. 249.3  M.f. C17H17N2 

COMMERCIALISATION

History Herbicidal properties of difenzoquat metilsulfate (the methyl sulfate) reported by T. R. O'Hare & C. B. Wingfield (Proc. North Cent. Weed Control Conf., 1973). This salt introduced by American Cyanamid Co. (now BASF AG); US registration in 1982.  Patents BE 792801; US 3882142  Manufacturers BASF

APPLICATIONS

difenzoquat metilsulfate

Mode of action Selective herbicide, absorbed by the leaves, with translocation mainly acropetally, and accumulation mostly near the treated area. Meristem inhibitor.  Uses Post-emergence control of wild oats in barley, wheat, rye, maize, ryegrass, and flax; applied at 750-1100 g/ha when used alone. Also used as a fungicide to control powdery mildew in cereals.  Formulation types SL; SP.  Compatibility Compatible with many broad-leaved herbicides, cereal fungicides, and the growth regulator chlormequat chloride.  Selected tradenames: 'Avenge' (herbicide) (BASF); 'Match' (fungicide) (BASF)

OTHER TRADENAMES

difenzoquat metilsulfate

'Yeh-Yan-Ku' (BASF) Discontinued names: 'Finaven' * (Cyanamid)

ANALYSIS

Product analysis by colorimetry (W. A. Steller, Anal. Methods Pestic. Plant Growth Regul., 1980, 11, 291). Residues determined by glc (W. A. Steller, loc. cit.). 

MAMMALIAN TOXICOLOGY

difenzoquat metilsulfate

Oral Acute oral LD50 for male rats 617, female rats 373, male mice 31, female mice 44 mg/kg.  Skin and eye Acute percutaneous LD50 for male rabbits 3540 mg/kg. Moderate skin and severe eye irritant (rabbits).  Inhalation LC50 (4 h) 0.50 mg/l.  NOEL In 2 y feeding trials, rats receiving 500 mg/kg diet showed no ill-effects.  ADI 0.2 mg/kg b.w. daily.  Toxicity class WHO (a.i.) II; EPA (formulation) I (tech.)  EC hazard Xn; R22| N; R50, R53 

ECOTOXICOLOGY

difenzoquat metilsulfate

Birds Dietary LC50 (8 d) for bobwhite quail >4640, mallard ducks >10 388 mg/kg diet.  Fish LD50 (96 h) for bluegill sunfish 696, rainbow trout 694 mg/l.  Daphnia LC50 (48 h) 2.63 mg/l.  Bees Contact LD50 36 mg/bee. 

ENVIRONMENTAL FATE