Specifications

NOMENCLATURE
Common name: propanil

Classification: herbicide

IUPAC name: 3',4'-dichloropropionanilide 

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

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. 

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.    

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
Animals The major metabolic pathway for propanil in microsomal incubations was acylamidase hydrolysis to 3,4-dichloroaniline (D. C. McMillan et al., Tox. Appl. Toxicol., 1990, 103, 90).  Plants In rice, propanil is hydrolysed by an aryl acylamidase to 3,4-dichloroaniline and propionic acid as metabolic intermediates.  Soil/Environment In soil, rapid microbial degradation to the aniline derivative occurs. Duration of activity in warm, moist conditions is only a few days. Degradation products are propionate which is rapidly metabolised to CO2, and 3,4-dichloroaniline which is bound (80% in 27 h) to the soil. Koc 239-800.