Description
Demeton-S-methyl is pale yellow in colour and oily and has a sulphur-like odour. It is
sparingly soluble in water but very rapidly soluble in common polar organic solvents such
as dichloromethane, 2-propanol, toluene, and n-hexane. It is a highly toxic, systemic, and
contact insecticide and acaricide and classified as Category I. It is used for the control of
insects, aphids, sawflies, and spider mites on cereals, fruits, vegetables, and ornamental
plants. On heating, demeton-S-methyl undergoes decomposition and emits very toxic
fumes, phosphorus oxides, and sulphur oxides.
Chemical Properties
Demeton-S-methyl is pale yellow in color, oily and has a sulfur-like odor. It is sparingly
soluble in water, but is very rapidly soluble in common polar organic solvents, such as
dichloromethane, 2-propanol, toluene, and n-hexane. It is a highly toxic, systemic, and
contact insecticide and acaricide and is classifi ed as Category I. It is used for the control
of insects, aphids, saw-fl ies, and spider mites on cereals, fruits, vegetables, and ornamental
plants. On heating, demeton-s-methyl undergoes decomposition and emits very toxic
fumes, phosphorus oxides, and sulfur oxides.
Chemical Properties
Demeton is a light brown liquid with an odor
of sulfur compounds; freezing/melting point ≤‐13
C
Chemical Properties
Demeton-methyl is a colorless to pale yellow
oily liquid. Unpleasant odor. It is a mixture of Demeton-S
and Demeton-O and may be formulated in a flammable
organic solvent that may alter the physical properties
shown here.
Uses
Demeton-S-methyl is a systemic insecticide used to control
sucking insects and mites in a wide range of crops and ornamentals.
Uses
Colinesterase inhibitor. Used as insecticide.
Production Methods
The commercial production of demeton-S-methyl involves synthesising this organophosphorothioate compound through a series of controlled chemical reactions. The process typically begins with the formation of 2-(ethylthio)ethanol, which is then reacted with dimethyl phosphorochloridothioate to yield demeton-S-methyl via esterification.
Definition
ChEBI: Demeton-S-methyl is an organic thiophosphate and an organothiophosphate insecticide. It has a role as an acaricide, an agrochemical and an EC 3.1.1.7 (acetylcholinesterase) inhibitor. It is functionally related to a 2-(ethylsulfanyl)ethanethiol.
General Description
Pale yellow oil. Used as an insecticide. Not registered as a pesticide in the U.S.
Reactivity Profile
Organophosphates, such as DEMETON-S-METHYL, 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
DEMETON-S-METHYL inhibits the nervous system and is absorbed readily through the skin. DEMETON-S-METHYL is a liquid organophosphorus insecticide. Poisonous; may be fatal if inhaled, swallowed or absorbed through skin. Contact may cause burns to skin and eyes.
Health Hazard
Demeton-S-methyl is highly toxic to animals and humans. Careless occupational exposures
to demeton-S-methyl cause severe symptoms of poisoning that include, but are not limited
to, headaches, nausea, vomiting, diarrhea, sweating, dizziness, tremors, lack of coordination,
hiccough, and memory loss. Prolonged exposures to high concentrations cause pupillary
constriction, blurred vision, muscle cramp, excessive salivation, weakness, sweating,
abdominal cramps, unconsciousness, respiratory distress, convulsions, respiratory failure,
and death.
Health Hazard
Highly toxic by all routes of exposure;cholinesterase inhibitor; toxic symptoms similar to those of Demeton and range formheadache, dizziness, blurred vision, and muscle spasms to gastrointestinal effects manifesting vomiting, diarrhea, and abdominalpain, as well as respiratory symptoms ofdyspnea, respiratory depression, and paral-ysis; high exposures may result in onset ofseizures and loss of consciousness; absorbedreadily through skin.
LD50 oral (rat): 30–60 mg/kg
LD50 oral (guinea pig): 110 mg/kg
LD50 skin (rat): 85 mg/kg
LC50 inhalation (rat): 500 mg/m
3 /4 h.
Fire Hazard
When heated to decomposition, DEMETON-S-METHYL emits very toxic fumes of oxides of phosphorus and sulfur. DEMETON-S-METHYL is a liquid organophosphorus insecticide. DEMETON-S-METHYL may burn but does not ignite readily. Container may explode in heat of fire. Fire may produce irritating or poisonous gases. Runoff from fire control water may give off poisonous gases. Hydrolyzed by alkali.
Mechanism of action
Systemic with contact and stomach action. Acetylcholinesterase (AChE) inhibitor.
Safety Profile
Poison by ingestion,
inhalation, sh contact, intraperitoneal, and
intravenous routes. Mutation data reported.
An insecticide. When heated to
decomposition it emits very toxic fumes of
POx and SOx. See also DEMETON-0 +
DEMETON-S and other demeton entries.
Potential Exposure
An organophosphate insecticide.
Those engaged in the manufacture, formulation and appli-
cation of the insecticide and acaricide on agricultural and
horticultural crops.
Metabolic pathway
The initial step for the biotransformation and photolytic activation of
demeton-S-methyl is by thiooxidation to oxydemeton-methyl; consequently
the metabolism of the two insecticides is very similar and
metabolic routes determined for oxydemeton-methyl should be taken as
applicable to the behaviour of demeton-S-methyl in the same system.
Most studies on the biotransformations of these compounds have used
oxydemeton-methyl.
storage
Demeton-S-methyl should be kept stored separately and away from food and feedstuffs.
Keep in a well-ventilated room.
Shipping
UN3278 Organophosphorus compound, liquid,
toxic, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous
materials, Hazard Technical Name Required, Potential
Inhalation Hazard (Special Provision 5). UN3017
Organophosphorus pesticides, liquid, toxic, flammable,
flash point not , 23
C, Hazard class: 6.1; Labels: 6.1-
Poisonous materials, 3-Flammable liquid. UN2810 Toxic
liquids, organic, n.o.s., Hazard Class: 6.1; Labels: 6.1-
Poisonous materials, Technical Name Required.
Degradation
Demeton-S-methyl was hydrolysed rapidly in alkaline media and more
slowly in acidic and neutral media. The half-lives at pH values 4,7 and 9
were 63,56 and 8 days, respectively. It is oxidised to oxydemeton-methyl
(2) (PM).
Incompatibilities
ncompatible 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, and epoxides. Strong oxidi-
zers may cause release of toxic phosphorus oxides.
Organophosphates, in the presence of strong reducing
agents such as hydrides, may form highly toxic and
flammable phosphine gas. Keep away from alkaline
materials.
Waste Disposal
The thiono-and thiolo-isomers of
this mixture are 50% hydrolyzed in 75 minutes and 0.85 min-
ute, respectively @ 20℃
and pH 13. At pH 9 and 70 ℃
, the
half-life of Demeton is 1.25 hour, but an pH 1-5 it is over
11 hours. Sand and rushed limestone may be added together
with a flammable solvent; the resultant mixture may be burned
in a furnace with afterburner and alkaline scrubber
.In
accordance with 40CFR165, follow recommendations for the
disposal of pesticides and pesticide containers. Must be dis-
posed properly by following package label directions or by
contacting your local or federal environmental control agency,
or by contacting your regional EPA office.
Precautions
During handling and use of demeton-S-methyl, occupational workers should use a face
shield or eye protection in combination with breathing protection, protective gloves, and
protective clothing. During use and handling of the chemical substance, workers should
not eat, drink, or smoke during work and wash hands before eating. Workers should
prevent generation of chemical mists and observe strict hygiene.
Pesticide Type
Insecticide; Acaricide
