Herbicide

HRAC  C2 WSSA  7; anilide

NOMENCLATURE

Common name propanil (BSI, E-ISO, (m) F-ISO, WSSA); DCPA (JMAF); no name (Germany)

IUPAC name 3',4'-dichloropropionanilide 

Chemical Abstracts name N-(3,4-dichlorophenyl)propanamide 

Other names 3,4-DCPA  CAS RN [709-98-8]  EEC no. 211-914-6  Development codes FW-734 (Rohm & Haas); Bayer 30 130; S 10145 (Bayer) 

PHYSICAL CHEMISTRY

Mol. wt. 218.1  M.f. C9H9Cl2NO  Form Colourless, odourless crystals; (tech., brown crystals).  M.p. 91.5 °C  V.p. 0.02 mPa (20 ºC); 0.05 mPa (25 ºC)  KOW logP = 3.3 (20 °C)  S.g./density 1.41 g/cm3 (22 ºC)  Solubility In water 130 mg/l (20 ºC). In isopropanol, dichloromethane >200, toluene 50-100, hexane <1 (all in g/l, 20 ºC). In benzene 7 ´ 104, acetone 1.7 ´ 106, ethanol 1.1 ´ 106 (all in ppm, 25 ºC).  Stability Hydrolysed in strongly acidic and alkaline media to 3,4-dichloroaniline and propionic acid; stable at normal pH range: DT50 (22 ºC) >>1 y (pH 4, 7, 9). Rapidly degraded in water by sunlight; photolysis DT50 12-13 h. 

COMMERCIALISATION

History Herbicide (Proc. South. Weed Control Conf., 1960, p. 20). Introduced by Rohm & Haas Co. in 1961, later by Bayer AG (1965) and by Monsanto Chemical Co.  Patents DE 1039779; GB 903766 to Bayer  Manufacturers Cedar; Chemia; Defensa; Griffin; Hegang Heyou; Hodogaya; Inquiport; Nufarm Ltd; Proficol; Rohm & Haas; Tifa; Westrade

APPLICATIONS

Biochemistry Photosynthetic electron transport inhibitor at the photosystem II receptor site.  Mode of action Selective contact herbicide with a short duration of activity.  Uses Contact herbicide used post-emergence in rice, at 2.5-5.0 kg/ha, to control broad-leaved and grass weeds, including Amaranthus retroflexus,Digitaria spp., Echinochloa spp., Panicum spp., and Setaria spp. Also used, in mixture with MCPA, in wheat. A mixture with carbaryl is used in citrus crops grown in sod culture.  Phytotoxicity Phytotoxic to many broad-leaved crops. Normally phytotoxic to crops which have been treated with organophosphate or carbamate insecticides.  Formulation types EC; SC; UL.  Compatibility Incompatible with a number of pesticides, particularly carbamates and organophosphates. Incompatible with liquid fertilisers.  Selected tradenames: 'Stam' (Rohm & Haas); 'Stampede' (Rohm & Haas); 'Khiumo' (Griffin); 'Kome' (Griffin); 'Nox' (Crystal); 'Propasint' (Westrade); 'RiceNil' (Gilmore); 'Riselect' (Isagro); 'Surcopur' (Bayer); mixtures: 'Lecspro' (+ fentrazamide) (Bayer)

OTHER TRADENAMES

'Strel' (Rohm & Haas); 'Agropur' (AgroSan); 'Herbax' (Westrade); 'Propanac' (Crystal); 'Propanex' (Crystal); 'Propanilo' (Crystal); 'Propax' (Crystal); 'Sorpur' (Bayer); 'Supernox' (Crystal); 'Wham' (Cedar, Crystal) mixtures: 'Anilonox' (+ anilofos) (Crystal); 'Arrosolo' (+ molinate) (Syngenta); 'Arroznox' (+ molinate) (Crystal); 'Bandito' (+ butachlor) (Crystal); 'Herbit-Plus' (+ MCPA-thioethyl) (Hokko); 'Londanil' (+ bensulfuron-methyl) (Crystal); 'Nox-D' (+ 2,4-D) (Crystal); 'Nox-MCP' (+ MCPA) (Crystal); 'Pendanil' (+ pendimethalin) (Crystal); 'Propacet' (+ quinclorac) (Crystal); 'Propanilate' (+ molinate) (Proficol); 'Pyrasulfonil' (+ pyrazosulfuron-ethyl) (Crystal); 'RiceMax' (+ clomazone) (FMC); 'Rizonil' (+ tetradifon) (Papaeconomou); 'Sable' (+ butachlor) (Proficol); 'Sierra' (+ mcpa-thioethyl) (Proficol); 'Sulfonil' (+ metsulfuron-methyl) (Crystal); 'Thionil' (+ thiobencarb) (Crystal); 'Vitanil' (+ butachlor) (Vipesco) Discontinued names: 'Cekupropanil' * (Cequisa); 'Synpran' * (Budapest Chemical)

ANALYSIS

Product analysis by glc (I. L. Adler & W. J. Zogorski, Anal. Methods Pestic. Plant Growth Regul., 1984, 13, 281). Residues determined by glc (idem, ibid.; ibid., 1972, 6, 692) or colorimetry of the 3,4-dichloroaniline formed on hydrolysis (C. F. Gordon et al., Anal. Methods Pestic., Plant Growth Regul. Food Addit., 1964, 4, 235). In water, by lc with u.v. detection (AOAC Methods, 1995, 992.14, 10.7.01). Methods for the determination of residues also available from Bayer. 

MAMMALIAN TOXICOLOGY

Oral Acute oral LD50 for rats >2500, mice c. 1800 mg/kg.  Skin and eye Acute percutaneous LD50 (24 h) for rats >5000 mg/kg. Not irritating to skin and eyes (rabbits). Not a skin sensitiser (guinea pigs).  Inhalation LC50 (4 h) for rats >1.25 mg/l air (dust).  NOEL (2 y) for rats 400, dogs 600 mg/kg diet.  ADI (US) 0.005 mg/kg b.w.  Water GV 20 mg/l (TDI 5 mg/kg b.w.).  Other Not mutagenic, not carcinogenic.  Toxicity class WHO (a.i.) III (Table 5); EPA (formulation) III ('Propanex'), II ('Supernox')  EC hazard Xn; R22 

ECOTOXICOLOGY

Birds Acute oral LD50 for mallard ducks 375, bobwhite quail 196 mg/kg. Dietary LC50 (5 d) for mallard ducks 5627, bobwhite quail 2861 ppm  Fish LC50 (48 h) for carp 8-11 mg/l.  Daphnia LC50 (48 h) 4.8 mg/l. 

ENVIRONMENTAL FATE