General Description
Colorless to yellow crystals. Used as a selective insecticide.
Reactivity Profile
A urea derivative.
Air & Water Reactions
Hydrolyzed in alkaline solution above pH 9.0.
Chemical Properties
The pure product is white crystals with an mp of 230-232°C. Its relative density is 1.56 and its vapor pressure is 1.32×10-5 Pa (50°C). It is readily soluble in acetonitrile and dimethyl sulfoxide, soluble in ethyl acetate, ethanol, and dichloromethane, and slightly soluble in ether, benzene, and petroleum ether. Its solubility in acetone is 6.5 g/L and in water is 0.1 mg/L. It is relatively stable to light and heat and is stable when stored at room temperature. It readily decomposes in the presence of alkali or strong acid and can be decomposed by soil microorganisms. The industrial product is white to light yellow crystals with an mp of 210-230°C.
Uses
An inhibitor of TCDD-induced CYP1a1 expression in HepG2 cells.
Uses
Diflubenzuron is a benzoylurea-based pesticide belonging to the benzamide class. Diflubenzuron is a chitin synthesis inhibitor. Diflubenzuron is used in both agriculture and forest management to selec
tively control insect pests, particularly moths and weevils.
Uses
Diflubenzuron is used for the control of a wide range of leaf-eating
insects in forestry, woody ornamentals and fruit. It controls major pests
on cotton, soyabean, citrus and tea and it also controls larvae of flies,
mosquitoes and locusts. Diflubenzuron is also used as an ectoparasiticide.
Uses
nsystemic insecticide used to control leaf-eating larvae and leaf miners in forestry, woody ornamentals and fruit trees.
Definition
ChEBI: A benzoylurea insecticide that is urea in which a hydrogen attached to one of the nitrogens is replaced by a 4-chlorophenyl group, and a hydrogen attached to the other nitrogen is replaced bgy a 2,6-difluorobenzoyl group.
Production Methods
The commercial production of diflubenzuron begins with the synthesis of the active ingredient through the reaction of 2,6-difluorobenzamide with 4-chlorophenyl isocyanate, typically catalysed by dimethylformamide in a controlled solvent environment to form N-[[(4-chlorophenyl)amino]carbonyl]-2,6-difluorobenzamide. The reaction mixture is then purified via filtration, extraction, and recrystallisation to achieve high purity while minimising impurities like 4-chloroaniline.
Agricultural Uses
Insecticide, Larvicide: Diflubenzuron is used primarily on citrus, cattle
feed, cotton, forestry, mushrooms, ornamentals, pastures,
soybeans, standing water, sewage systems, and wide-area
general outdoor treatment sites. The insecticide behaves as
a chitin inhibitor to inhibit the growth of many leaf-eating
larvae, mosquito larvae, aquatic midges, rust mite, boll weevil, and house-black-, and stable-flies. Diflubenzuron was
first registered in the United States in 1979 for use as an
insecticide.
Trade name
ADEPT®; ASTONEX®; DIMILIN®;
DIMILIN® FLO; DIMILIN® WG-80; DU-112307®;
DUPHAR® PH 60-40; ODC-45®; DIFLURON®;
DU 112307®; LARGON®; LARVAKIL®;
MICROMITE®; OMS 1804®; PDD 60401®; PH 60-
40®; PHILIPS-DUPHAR® PH 60-40; TH 60-40®;
THOMPSON-HAYWARD® 6040; VIGILANTE®
Mechanism of action
Selective, non-systemic with contact and stomach action, acts by inhibiting chitin synthesis. Inhibitor of chitin biosynthesis affecting CHS1.
Environmental Fate
Soil. The half-life in soil is <1 week (Hartley and Kidd, 1987). Di?ubenzuron degrades more rapidly in neutral or basic conditions but more slowly under acidic conditions (pH <6) (Ivie et al., 1980).
Chemical/Physical. Hydrolyzes in water to 4-chlorophenylurea (Verschueren, 1983).
Metabolic pathway
Diflubenzuron was the first active substance commercialised as a
benzoylurea insect growth regulator and there is extensive published
information on its degradation and metabolism. Detailed studies of the
degradation in soils have shown that cleavage of the urea linkage is
the major process. This also occurs in plants, insects and mammals but
the formation of products in which diflubenzuron is hydroxylated in
both rings is also an important metabolic process.
Degradation
Diflubenzuron was shown to be stable to hydrolysis in aqueous solution
at acidic pH (DT50> 56 days at pH 4) but was readily hydrolysed at pH 10
(DT50 <3 days). In distilled water the DTa was 7 days (Ivie et al., 1980).
The major degradation products isolated were 4-chlorophenylurea (2)
and 2,6-difluorobenzoic acid (3). An additional minor product was 2,6-
difluorobenzamide (4). The hydrolysis products are shown in Scheme 1.
Additional products were formed under extreme conditions (121 °C
under pressure).
Aqueous solutions of diflubenzuron are reported to be unstable to light
but the solid is stable in sunlight (PM).
Toxicity evaluation
Diflubenzuron is an odorless, white, crystalline solid with
a melting point of 230–232 C. It is almost insoluble in water (0.2 mg l1) and poorly soluble in apolar organic solvents.It is almost nonvolatile. It is relatively stable in
acidic and neutral media but hydrolyses under alkaline
conditions.
Diflubenzuron is difficult to be degraded in sterilized water
under neutral or acidic conditions. However, it is degraded
rapidly under field conditions. Application of diflubenzuron to
water resulted rapid partition to sediment; the parent
compound and 4-chlorophenylurea (CPU) may persist on
sediment for more than 30 days.
The rate of degradation of diflubenzuron in soil is strongly
dependent on the particle size. For larger particles
(10 microns), the half-life is 8–16 weeks and for smaller
particles (2 microns), it is 0.5–1 week. Almost all of the parent
compound breaks down to form 2,6-difluorobenzoic acid
(DFBA) and CPU. A very minor amount forms 4-chloroaniline
(PCA) which rapidly binds to the soil. Under field conditions,
diflubenzuron has very low mobility.
Very little diflubenzuron is absorbed, metabolized, or
translocated in plants. It also is not readily taken up from
treated soil.
Diflubenzuron has very low vapor pressure (<2×10-7 Pa
at 25°C) and its atmospheric half-life is only several hours.
Therefore, it is not expected that diflubenzuron will be present
in air for extended periods and the long-range transport and
redeposition of diflubenzuron is expected to be negligible.
References
[1] DAHM P A. Pesticide chemistry in the 20th century[J]. Pesticide Biochemistry and Physiology, 1978, 9 2: Pages 222-223. DOI:
10.1016/0048-3575(78)90084-6[2] ALINE LIMA DE BARROS. Genotoxic and mutagenic effects of diflubenzuron, an insect growth regulator, on mice.[J]. Journal of Toxicology and Environmental Health-Part A-Current Issues, 2013, 76 17: 1003-1006. DOI:
10.1080/15287394.2013.830585[3] R O HEUCKEROTH J I G L Glaser. Heteroatom-substituted fatty acid analogs as substrates for N-myristoyltransferase: an approach for studying both the enzymology and function of protein acylation.[J]. Proceedings of the National Academy of Sciences of the United States of America, 1988, 85 23: 8795-8799. DOI:
10.1073/pnas.85.23.8795
Pesticide Type
Insecticide
