Chemical Properties
Clear Colorless Liquid
Uses
A cholinesterase inhibitor. Insecticide; acaricide.
Definition
ChEBI: An dialkyl phosphate resulting from the formal condensation of the acidic hydroxy group of dimethyl hydrogen phosphate with the alcoholic hydroxy group of 1,2-dibromo-2,2-dichloroethanol. An organophosphate insecticide, it is no longer approved for use wit
in the European Union.
Uses
Insecticide; acaricide.
General Description
DIBROM is a white solid that may be dissolved in a liquid organic carrier with a pungent odor. DIBROM is a water emulsifiable liquid. DIBROM is insoluble in water and sinks in water. DIBROM can cause illness by inhalation, skin absorption and/or ingestion. The primary hazard is the threat to the environment. Immediate steps should be taken to limit its spread to the environment. If DIBROM is in liquid form, DIBROM can easily penetrate the soil and contaminate groundwater and nearby streams. DIBROM is used as a pesticide.
Air & Water Reactions
Practically insoluble in water [Farm Chemicals Handbook]. Hydrolyzed slowly in presence of water.
Reactivity Profile
DIBROM is incompatible with the following: Strong oxidizers, acids, sunlight, water [Note: Corrosive to metals. Hydrolyzed in presence of water.] . Unstable in presence of Iron [USCG, 1999]. Organophosphates are susceptible to formation of highly toxic and flammable phosphine gas in the presence of strong reducing agents such as hydrides. Partial oxidation by oxidizing agents may result in the release of toxic phosphorus oxides.
Health Hazard
INHALATION OR INGESTION: Symptoms secondary to cholinesterase inhibition are: headache, giddiness, nervousness, blurred vision, weakness, nausea, cramps, diarrhea, chest discomfort, sweating, miosis, tearing, salivation, and other excessive respiratory tract secretion, vomiting, cyanosis, muscle twitching, and convulsions. EYES: Irritating. SKIN: Irritating-can cause dermatitis.
Fire Hazard
May be combustible. (NOAA, 2007)
Hazard
Technical compound is a moderately volatile liquid. Bp 110C (0.5 mm Hg). Insoluble in water;
slightly soluble in aliphatic solvents; very soluble
in aromatic solvents; hydrolyzes in water.
Potential Exposure
A potential danger to those involved
in the manufacture, formulation, and application of this
insecticide, fungicide, bactericide, acaricide. Also used in
cooling towers, veterinary medicine, pulp and paper mill
systems; hospitals, swimming pools; and bathrooms.
First aid
If this chemical gets into the eyes, remove any
contact lenses at once and irrigate immediately for at least
15 minutes, occasionally lifting upper and lower lids. Seek
medical attention immediately. If this chemical contacts the
skin, remove contaminated clothing and wash immediately
with soap and water. Speed in removing material from skin
is of extreme importance. Shampoo hair promptly if contaminated.
Seek medical attention immediately. If this
chemical has been inhaled, remove from exposure, begin
rescue breathing (using universal precautions, including
resuscitation mask) if breathing has stopped and CPR if
heart action has stopped. Transfer promptly to a medical
facility. When this chemical has been swallowed, get medical
attention. Give large quantities of water and induce
vomiting. Do not make an unconscious person vomit.
Effects may be delayed. Medical observation is recommended.
Shipping
UN2811 Toxic solids, organic, n.o.s., Hazard
Class: 6.1; Labels: 6.1-Poisonous materials, Technical
Name Required. UN2783 Organophosphorus pesticides,
solid, toxic, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.
UN3018 Organophosphorus pesticides, liquid, toxic,
Hazard Class: 6.1; Labels: 6.1-Poisonous materials.
Incompatibilities
Incompatible with oxidizers (chlorates,
nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions.
Keep away from alkaline materials, strong bases,
strong acids, oxoacids, epoxides. Hydrolyzed in presence of
water. Degraded by sunlight. Decomposes when heated; on
contact with acids, acid fumes; bases, producing fumes of
hydrogen chloride, hydrogen bromide, phosphorous oxides.
Reacts with acids, strong oxidizers in sunlight. Slowly
reacts with water; hydrolysis is; corrosive to metals.
Attacks some plastics, rubber and coatings.
Description
Naled is an organophosphate insecticide and acaricide that inhibits acetylcholinesterase (AChE) and butyrylcholinesterase (BChE).
1 It reduces the number of
A. sollicitans mosquitos by 97% after one hour when aerially applied at a concentration of 0.1 pounds per acre.
2 Naled (125 ppm AI) induces 100 and 64% mortality of
T. telarius adults and immature mites, respectively, in an immediate contact toxicity test but does not induce mortality in mite eggs.
3 It is toxic to rats with an LD
50 value of 250 mg/kg.
4 Formulations containing naled have been used in the control of mosquitoes in public areas and of crop-damaging insects in agriculture.
Description
Sensitization to Naled seems to be rare.
Waste Disposal
This pesticide is more
stable to hydrolysis than dichlorvos (50% hydrolysis at pH
9 @ 37.5℃ in 301 minutes). It is unstable in alkaline conditions,
in presence of iron; and is degraded by sunlight.
About 10% hydrolysis per day is obtained in ambient
water. Incineration is recommended for large amounts.
In accordance with 40CFR165, follow recommendations for the disposal of pesticides and pesticide containers. Must
be disposed properly by following package label directions
or by contacting your local or federal environmental control
agency, or by contacting your regional EPA office.
Physical properties
Colorless to pale yellow liquid or solid with a pungent odor
Production Methods
Naled is synthesised through a multi-step process that begins with the preparation of the halogenated ethyl alcohol intermediate, specifically 1,2-dibromo-2,2-dichloroethanol. This intermediate is then reacted with dimethyl phosphorochloridate in the presence of a base such as pyridine or triethylamine, facilitating the formation of the phosphate ester bond. The reaction typically occurs under controlled temperature and anhydrous conditions to prevent hydrolysis and degradation, as naled is sensitive to moisture and acidic environments. After the coupling reaction, the crude product is purified through distillation or solvent extraction, yielding a stable, high-purity insecticide.
Agricultural Uses
Insecticide, Fungicide, Bactericide, Acaricide: Naled is a fast-acting, nonsystemic contact and stomach
insecticide used to control aphids, mites, mosquitoes,and flies on crops and in greenhouses, mushroom houses,
animal and poultry houses, kennels, food-processing
plants, and aquaria and in outdoor mosquito control. Liquid
formulations can be applied to greenhouse heating pipes to
kill insects by vapor action. It has been used by veterinarians
to kill parasitic worms (other than tapeworms) in dogs.
Naled may no longer be used in and around the home by
residents or professional applicators. Naled is available in
dust, emulsion concentrate, liquid, and ULV formulations.
Also used in cooling towers, veterinary medicine, pulp and
paper mill systems, hospitals, swimming pools, and bathrooms.
A U.S. EPA restricted Use Pesticide (RUP). Not
approved for use in EU countries. Registered for use in
the U.S.
Trade name
AI3-24988®; ARTHODIBROM®;
BROMCHLOPHOS®; BROMEX®; DIBROM®;
FLYKILLER®; LUCANAL®; HIBROM®; ORTHO®
4355; ORTHODIBROM®; ORTHODIBROMO®;
PROKIL® Naled; TRUMPET®
Mechanism of action
Non-systemic with rapid contact and stomach action. Acetylcholinesterase (AchE) inhibitor.
Carcinogenicity
When dogs were given 0.2, 2.0,
or 20 mg/kg/day naled by gavage for 1 year, cholinergic signs
(soft stools/diarrhea, salivation, and emesis), increases in
mineralization of spinal cord, and mild testicular degeneration
in males occurred at 2 and 20 mg/kg/day dose
levels . Erythrocyte and brain cholinesterase activities
were depressed at the same dose levels. Anemia also
occurred at 2 and 20 mg/kg/day, and erythrocyte count,
hemoglobin, and hematocrit were reduced. At 20 mg/kg/
day dose level, liver and kidney weights increased but
these were not accompanied by histopathological changes.
There was no evidence of carcinogenicity.
Environmental Fate
Chemical/Physical. Completely hydrolyzed in water within 2 days (Windholz et al.,
1983). In the presence of metals or reducing agents, naled loses bromine, forming dichlorvos
(Hartley and Kidd, 1987)
Naled emits toxic fumes of bromines, chlorides and phosphorus oxides when heated
to decomposition (Lewis, 1990).
Metabolic pathway
Naled is produced by the photochemical bromination of the dichlorovinyl
moiety of dichlorvos. The main route of naled metabolism and transformation
in the environment is through debromination to dichlorvos
which is probably the active cholinesterase inhibitor in vivo. Naled is also
rapidly hydrolysed to bromodichloroacetaldehyde in aqueous environments:
consequently much of its detoxification is likely to be via a nonenzymatic
hydrolytic route.
Solubility in water
Freely soluble in ketone, alcohols, aromatic and chlorinated hydrocarbons but sparingly soluble in
petroleum solvents and mineral oils (Windholz et al., 1983)
Degradation
Naled is stable when dry but it is rapidly hydrolysed in aqueous media
and more rapidly in alkaline and acidic media. It is degraded by sunlight.
In the presence of metals and reducing agents, bromine is lost and dichlorvos
(2) is formed (PM). In unbuffered aqueous solution naled was rapidly
hydrolysed via two routes, one leading to the formation of dimethyl
phosphate (3) and bromodichloroacetaldehyde (4) and the second via
desmethyhaled (5), which further decomposed to yield bromodichloroacetaldehyde
(4) and monomethyl phosphate (6) as shown in Scheme 1.
Naled was found to be much less hydrolytically stable than dichlorvos
and exhibited a maximum stability at pH 4 (Jentzen and Fischer, 1978).
References
[1] P. HERZSPRUNG R N L Weil. Measurement of Bimolecular Rate Constants k i of the Cholinesterase Inactivation Reaction by 55 Insecticides and of the Influence of Various Pyridiniumoximes on k i[J]. International Journal of Environmental Analytical Chemistry, 1992, 47 1: 181-200. DOI:
10.1080/03067319208027028[2] MITCHELL H R. Part I: Comparison of an “As-Needed” and “Full-Season” Insecticide Application Schedule for Control of Cotton Insects in Northeast Louisiana. Part II: the Utilization of Vegetable Oil as a Carrier for Ultra-Low-Volume Aerial Sprays Applied for Cotton Insect Control.[C]. 1900: 0. DOI:
10.31390/gradschool_disstheses.4064[3] M. MATLLOUX F O M. The Effects of Acaricides on the Developmental Stages of the Two-Spotted Spider Mite, Tetranychu telarius[J]. Journal of Economic Entomology, 1962, 55 1: 479-483. DOI:
10.1093/jee/55.4.479[4] GAINES T B. Acute toxicity of pesticides[J]. Toxicology and applied pharmacology, 1969, 14 3: Pages 515-534. DOI:
10.1016/0041-008x(69)90013-1
Pesticide Type
Insecticide; Acaricide
