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Chemical Fact Sheet

Chemical Abstract Number (CAS #) 4482557
CASRN 4482-55-7
SynonymsFENURON
N,N-Dimethyl-N-phenylurea, Electrum, Premalox, Quintex
Molecular FormulaC9H12N2O

Link to the National Library of Medicine's
Database for more details on this compound.

UseWeed and brush killer. [R5, 987] Herbicide [R6] Control of woody plants and deep rooted perennial weeds, particularly on non crop land. Often used in combination with chloropropham to extend the weed spectrum and range of crops. [R3
Apparent ColorWhite, crystalline solid; Colorless crystalline solid; Colorless crystals
OdorN/A
Boiling Point N/A
Melting Point 133-134 DEG C
Molecular Weight 164.21
MiscNon-corrosive DENSITY:1.08 at 20 deg C/20 deg C SOLUBILITY: 3850 ppm @ 25 deg C; Sparingly sol in water (0.29% at 24 deg C); Solubility (25 deg C): 3.85 g/l water; sparingly soluble in hydrocarbons.; In ethanol 108.8, diethylether 5.5, acetone 80.2, benzene 3.1, chloroform 125, n-hexane 0.2, groundnut oil 1.0 (all in g/kg at 20-25 deg C); In water 3.85 g/l at 25 deg C Intense mass spectral peaks: 72 mz (100%), 164 mz (26%), 44 mz (25%), 65 mz (22%). 1.6x10-4 mm Hg at 60 deg C Compatible with other wettable-powder herbicides. Colorless crystals /Fenuron trichloroacetate/ Molecular weight: 327.6 /Fenuron trichloroacetate/ Melting point: 65-68 deg C /Fenuron trichloroacetate/ Sol in water 4.8 g/l at room temperature. Moderately sol in acetone and aromatic solvents. sparingly soluble in petroleum oils. /Fenuron trichloroacetate/ Henry's Law constant of 9.71X10-10 atm-cu m/mole at 25 deg C (estimated) No specific antidote known. Symptomatic treatment. [R10] Rats given 500 ppm in food for 90 days showed no ill effects. However, in guinea pigs daily oral doses of 15 to 150 mg/kg for 10 months produced anemia, hypothyroidism and structural alterations in liver, kidney, spleen and myocardium. Cows and sheep receiving 2 to 5 daily doses of 500 mg/kg showed anorexia and incoordination progressing to death. In surviving animals, recovery was extremely slow. Necropsy revealed congestion of lungs and myocardial hemorrhages. Practically nonirritating to intact skin of guinea pigs and only moderately irritating to abraded skin. Not a skin sensitizer. [R1,p. LL-331] Substituted urea compounds (... fenuron) cause vomiting, ataxia, and urticaria. [R11] In 90 day feeding trials, rats receiving 500 mg/kg diet showed no ill effects. [R12] LD50 Rat acute oral 6400 mg/kg [R5, 988] LD50 Rat oral 7500 mg/kg [R6] LD50 Rat oral 4000-5700 mg/kg /Fenuron trichloroacetate/ [R3] LC50 Guppy 610 mg/l/48 hr /Conditions of bioassay not specified/ [R3] Nonselective systemic herbicide, absorbed predominantly by the roots, with translocation acropetally in the xylem. [R3] Dealkylation and hydroxylation of aromatic ring of phenylureas take place during animal metabolism. [R13] Inhibits photosynthesis. [R3] Fenuron may be released to the environment primarily during its use as a herbicide. If released to the atmosphere, degradation of vapor-phase fenuron by reaction with photochemically produced hydroxyl radicals (estimated half-life of 2.3 hrs) will be important. Photolysis may be important and particulate-phase fenuron will be removed from air via dry deposition. If released to soil, biodegradation will be the primary fate process. A complete degradation half-life of 2.2-4.5 months was measured for fenuron in soil. Photolysis may be important on soil surfaces exposed to sunlight. Adsorption to soil will not be important. In water, volatilization, adsorption to sediment, hydrolysis and bioconcentration in aquatic organisms will not be important. Biodegradation is expected to be the primary fate process and some photodegradation may occur. Workers may be exposed via dermal contact and inhalation of dust. (SRC) Fenuron is released to the environment during its use as a herbicide(1). [R14] TERRESTRIAL FATE: In soil, enzymic and microbial degradation involves step by step N-demethylation. [R3] TERRESTRIAL FATE: The complete degradation of fenuron in soil has been experimentally determined to be 4.5 months at 15 deg C and 2.2 months at 30 deg C(1). Biodegradation will be the primary fate process in soil(2). Measured Kocs of 27(3) and 43(4) indicate that adsorption to soil will not be important(SRC). A visible change in color occurred within 2 hours when paper saturated with fenuron was exposed to sunlight(5) suggesting that some fenuron may be removed from soil surfaces via direct photolysis(SRC). [R15] AQUATIC FATE: After 2 weeks, approximately 20% of 10 ug/L fenuron remained in raw river water samples exposed to sunlight and artificial fluorescent light(1). Biodegradation is expected to be the primary fate process in aquatic ecosystems(2,SRC). Measured Kocs of 27(3) and 43(4) indicate that adsorption of fenuron from the water column to sediment and suspended material will not be important(SRC). An estimated BCF of 6(3) indicates that fenuron will not bioconcentrate in fish(SRC). A visible change in color occurred within 2 hours when paper saturated with fenuron was exposed to sunlight(5) suggesting that some fenuron may be removed from water via direct photolysis(SRC). Volatilization from water will not be important(7) based on a low Henry's Law constant of 1.68X10-10 atm-cu m/mole at 25 deg C(6,SRC). [R16] ATMOSPHERIC FATE: Based on a measured water solubility of 4,027 mg/L at 25 deg C(1) and an estimated Henry's Law constant of 9.71X10-10 atm-cu m/mole at 25 deg C(2), the vapor pressure of fenuron can be estimated to be 1.81E-5 mm Hg at 25 deg C(SRC). This vapor pressure value suggests that fenuron will exist in the vapor and particulate phases in the ambient atmosphere(3). Vapor-phase fenuron is rapidly degraded in the ambient atmosphere by reaction with photochemically formed hydroxyl radicals; the half-life for this reaction in air can be estimated to be about 2.3 hrs(4,SRC). A visible change in color occurred within 2 hours when paper saturated with fenuron was exposed to sunlight(5) suggesting that fenuron may be removed from the atmosphere via direct photolysis(SRC). Particulate-phase fenuron is removed via dry deposition(SRC). [R17] Based on extensive biological and chemical studies, the disappearance of fenuron from soil is due primarily to microbial degradation; however, no quantitative data were given(1). In a pure culture study, fenuron was degraded 10% by the soil fungus Rhizoctonia solani after 6 days(2). [R18] Fenuron ... /is/ degraded by light [R19] The rate constant for the vapor-phase reaction of fenuron with photochemically produced hydroxyl radicals can be estimated to be 1.68X10-10 cu cm/molecule-sec at 25 deg C which corresponds to an atmospheric half-life of about 2.3 hrs at an atmospheric concn of 5X10+5 hydroxyl radicals per cu cm(1,SRC). Photodecomposition of fenuron saturated on paper was exhibited at wavelengths <280 nm(2). In the same study, a visible change in color occurred within 2 hours of exposure to sunlight indicating the importance of photodecomposition under field conditions(2). Possible photodecomposition products are aniline, o-amino-N,N-dimethylbenzamide and p-amino-N,N-dimethyl benzamide(3). Hydrolysis will not be important(SRC). [R20] Based on an estimated bioconcentration factor of 1-6(1), fenuron is not expected to bioaccumulate in fish(SRC). [R21] Average Koc values of about 27(1) and 43(2) have been experimentally determined for fenuron. Based on a suggested classification scheme(3), these Koc values indicate that fenuron will have very high soil mobility. [R22] The Henry's Law constant for fenuron can be estimated to be 9.71X10-10 atm-cu m/mole at 25 deg C based on a structure activity relationship(1). According to a suggested classification scheme(2), this value of Henry's Law constant indicates that fenuron will be essentially nonvolatile from water. [R23] SURFACE WATER: Fenuron was qualitatively detected in river water(1). [R24] In plants, N-demethylation occurs step by step. [R3] In occupational settings, workers may be exposed to fenuron via inhalation of dust and dermal contact. (SRC) Product analysis of fenuron is based on hydrolysis. Residues may be determined by colorimetry. [R2]

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