Description
Formothion is a pale yellow liquid or crystalline mass,
decomposes on distillation, mp 25–26 C, vp 0.113 mPa
(20 C). It is poorly soluble in water (2.6 g/L at
24 C) and miscible with most organic solvents, except
aliphatic hydrocarbons. Log Kow = 1.47. Formothion is
hydrolyzed in aqueous media to dimethoate (activation)
and dimethoate carboxylic acid (degradation): DT
50 (23 C)
at pH 3–9 is less than 1 d.
Chemical Properties
Yellow liquid.Insoluble in
water; miscible with common organic solvents.
Chemical Properties
Formothion is an odorless, yellowish viscous
oil or crystalline mass.
Uses
Formothion is used to control sucking pests and internally feeding
larvae in a variety of crops.
Uses
Acaricide, systemic insecticide.
Definition
ChEBI: Formothion is a dicarboximide.
Production Methods
Formothion is commercially produced through esterification and thiophosphorylation reactions involving dimethylthiophosphoric acid and formamide derivatives. It begins with the preparation of O,O-dimethyl dithiophosphoric acid, which is typically obtained by reacting phosphorus pentasulfide with methanol. This intermediate is then reacted with formamide or a substituted formamide under controlled conditions to form the active ester compound. The reaction involves thiophosphorylation, where the sulphur-containing phosphorus group is bonded to the nitrogen-containing formamide moiety. The process is carried out in organic solvents such as toluene or xylene, under reflux and with acid or base catalysts to optimise yield.
General Description
Viscous yellow oil or a crystalline mass. Used as an insecticide and acaricide on crops and ornamentals. Not presently produced commercially in the U.S.
Air & Water Reactions
hydrolyzed by water especially under alkaline conditions. [EPA, 1998].
Reactivity Profile
Organophosphates, such as FORMOTHION, 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.
Hazard
Cholinesterase inhibitor.
Health Hazard
FORMOTHION is one of the least toxic systemic organophosphates. FORMOTHION is a compound of low to moderate toxicity. It causes the depression of cholinesterase, leading to accumulation of acetylcholine in the nervous system, which is believed to be responsible for the symptoms.
Fire Hazard
When heated to decomposition, FORMOTHION emits very toxic fumes of nitrogen oxides, phosphorus oxides and sulfur oxides. FORMOTHION is an organophosphorus insecticide. Some of these materials may burn but none of them ignite readily. Container may explode in heat of fire. Fire and runoff from fire control water may produce irritating or poisonous gases. Avoid alkaline pesticides; hydrolyzed by water especially under alkaline conditions.
Agricultural Uses
Insecticide, Acaricide: Formothion is a systemic and contact insecticide
used to control spider mites, aphids, psyllids, mealy bugs,
whiteflies, jassids, leaf miners, ermine moths, and fruit
flies. It is used on tree fruits, vines, olives, hops, cereals,
sugar cane, rice. Formothion is available as an emulsifiable
concentrate and an ultra-low-volume spray. A U.S. EPA restricted Use Pesticide (RUP). Not approved for use in EU
countries
Trade name
AFLIX®; ANTHIO®; ANTIO®; CP
53926®; S 6900®; SAN 244 I®; SAN 6913 I®; SAN
71071®; SPENCER S-6900®; VEL 4284®
Mechanism of action
Systemic with contact action. Acetylcholinesterase (AchE) inhibitor.
Safety Profile
Poison by ingestion,
inhalation, sh contact, and intravenous
routes. Mutation data reported. When
heated to decomposition it emits very toxic
fumes of NOx, POx, and SOx. See also
ESTERS.
Potential Exposure
Formothion is an insecticide and acar icide for use on crops and ornamentals. Formothion is not
currently produced commercially in the U.S.
First aid
If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Speed in removing material from skinis of extreme importance. Shampoo hair promptly if contaminated. Seek medical attention immediately. If thischemical has been inhaled, remove from exposure, beginrescue breathing (using universal precautions, includingresuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit. Keepvictim quiet and maintain normal body temperature. Effectsmay be delayed; keep victim under observation.
Metabolic pathway
Formothion is broken down in aqueous solution to approximately equal
amounts of dimethoate and dimethoate carboxylic acid, the first of which
is an activation step and the latter a degradative one. All studies which
have investigated the fate of formothion in biological systems have
identified these two metabolites but there is evidence that their formation
is purely base-catalysed and not enzyme-catalysed. In this respect, the
amide group of formothion is much more labile than that of dimethoate
since dimethoate carboxylic acid has only been reported in metabolic
studies and is not formed by base-catalysed hydrolysis of dimethoate.
storage
Color Code—Blue: Health Hazard/Poison: Storein a secure poison location. Prior to working with thischemical you should be trained on its proper handling andstorage. Store in tightly closed containers in a cool, wellventilated area away from alkaline materials. Wherepossible, automatically pump liquid from drums or otherstorage containers to process containers.
Shipping
UN3018 Organophosphorus pesticides, liquid,
toxic, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.
Degradation
Formothion is hydrolysed by water to dimethoate (2) and dimethoate
carboxylic acid (3). Dilute solutions in non-polar organic solvents are
stable (PM). El-Oshar and Dauterman (1977) investigated the hydrolysis
of [O-
14C-methyl]formothion in 1.0 M phosphate buffer at pH values
between 5.5 and 8.0 at 37 °C. The amounts of unchanged formothion and
products were assessed after 30 min. At all pH values the amounts of
dimethoate (2) and dimethoate carboxylic acid (3) were approximately
equal, indicating that the rate of attack by the hydroxyl ion was equal at
both carbonyl groups. The rate of hydrolysis was pH dependent with
16.4% hydrolysis at pH 5.5, 65.2% hydrolysis at pH 7.0 and 96.7%
hydrolysis at pH 8.0 after 30 min. The route leading to dimethoate carboxylic
acid would yield N-methylformamide (4) as the additional product.
A suggested route for the base-catalysed hydrolysis of formothion
is shown in Scheme 1.
Toxicity evaluation
The acute oral
LD
50 for rats is 365–500 mg/kg. Inhalation LC50 (4 h) for
rats is 3.2 mg/L air. NOEL (2 y) for rats is 80 mg/kg diet
(4 mg/kg/d). ADI is 0.02 mg/kg b.w.
Incompatibilities
Strong oxidizers may cause release of
toxic phosphorus oxides. Organophosphates, in the pres ence of strong reducing agents such as hydrides, may form
highly toxic and flammable phosphine gas. Keep away
from alkaline materials.
Waste Disposal
In accordance with 40CFR
165 recommendations for the disposal of pesticides and
pesticide containers. Must be disposed properly by follow ing package label directions or by contacting your local or federal environmental control agency, or by contacting
your regional EPA office.
Pesticide Type
Insecticide; Acaricide
