Molecular weight:310.7. Physical form:Colourless crystals; ( tech.,
off-white to yellow crystals). Density:1.56; Composition:Tech.
grade diflubenzuron is 95% pure. Melting point:228 °C; ( tech.,
210-230 °C, decomp.); Vapour pressure:1.2×10-4 mPa (25 °C) (gas
saturation method); Partition coefficient(n-octanol and water):logP
= 3.89; Solubility:In water 0.08 mg/l ( pH 7, 25 °C). In n-hexane
0.063, toluene 0.29, dichloromethane 1.8, methanol 1.1 (all in g/l,
20 °C).; Stability:Light-sensitive when in solution, but stable to
sunlight as a solid. <0.5% decomposition after 1 d storage at
100 °C; <0.5% after 7 d at 50 °C. In aqueous solution (20 °C),
stable at pH 5 and 7 ( DT50 >150 d). Almost insoluble in apolar
solvents. Moderate to good in most polar-to-very polar solvents.
Oral:Acute oral LD50 for rats and mice >4640 mg/ kg. Percutaneous:Acute percutaneous
LD50 for rabbits >2000, rats >10 000 mg/kg. Not a skin irritant;
slight eye irritant (rabbits). Not mutagenic.Not teratogenic. Not a
skin sensitiser (guinea-pigs). Inhalation: LC50 for rats >2.88 mg/l.
Algae: LC50 for Selenastrum capricornutum >0.3 mg/l.Bees:Not hazardous to bees and predatory insects; LD50 (oral and contact) >100 µg/bee.Birds:Dietary 50 (8 d) for
bobwhite quail and mallard ducks >4640 mg/kg diet.Daphnia: LC50 (48 h) 7.1 µg/l.Fish: LC50 (96 h) for zebra fish (Brachydanio rerio) >0.2, rainbow trout >0.2 mg/l.Worms: NOEC for Eisenia foetida 780 mg/kg substrate.Other aquatic spp.: LC50 for molluscs >200 mg/l.
Animals:In rats, following oral administration, elimination is
partly as the unchanged parent compound in the faeces, partly as
hydroxylated metabolites (for c. 80%) and as 4-chlorophenylurea plus 2,6-difluorobenzoic acid (for c. 20%). Soil: Diflubenzuron is strongly absorbed by soil/humic acid
complex and is virtually immobile in soil. Rapidly degraded in
soil, with a half-life of <7 days. The principal degradation
products are 4-chlorophenylurea and 2,6-difluorobenzoic acid.
Plant:Non-systemic. Not metabolised on plants ( idem, ibid.).
SOIL PARTICLE ADSORPTION: Strongly adsorbed by soil/humic acid
complex; virtually immobile.
WATER SOLUBILITY: Almost insoluble, 0.08 mg/l at 20°C.
DEGRADATION/METABOLISM: In soil, rapidly degraded by a
microbiological process. Half-life in soil of WP (avg. particle
sizes 2-3 micron) is 3-4 days.
Signal Word:CAUTION; Hazard Class:III (Slightly hazardous)