| Identification | More | [Name]
Vamidothion | [CAS]
2275-23-2 | [Synonyms]
dimethyl phosphorothioate 2-((2-mercaptoethyl)thio)-n-methylpropionamide s-ester
KILVAL
O,O-DIMETHYL S-[2-(1-METHYL-2-METHYLAMINO-2-OXOETHYLTHIO)ETHYL] PHOSPHOROTHIOATE
O,O-DIMETHYL S-2-(1-METHYLCARBAMOYLETHYLTHIO)ETHYL PHOSPHOROTHIOATE
VAMIDOTHION
Vamidothion(content>10%)
10465rp
2-(2-dimethoxyphosphinoylthioethylthio)-n-methylpropionamide
americancyanamid-43073
dimethyls-(2-(1-methylcarbamoylethylthio)ethyl)phosphorothiolate
ent26,613
n-methyl-3-thia-2-methyl-valeramiddero,o-dimethylthiolphosphorsaeure
n-methylo,o-dimethylthiolophosphoryl-5-thia-3-methyl-2-valeramide
nph83
nph-83
o,o-dimethylphosphorothioates-esterwith2-((2-mercaptoethyl)thio)-n-methylp
o,o-dimethyls-(2-((1-methyl-2-(methylamino)-2-oxoethyl)thio)ethyl)phosphoroth
o,o-dimethyls-2-(1-n-methylcarbamoylethylmercapto)ethylthiophosphate
phosphorothioicacid,o,o-dimethylester,s-esterwith2-((2-mercaptoethyl)thio
r.p.10,465 | [EINECS(EC#)]
218-894-8 | [Molecular Formula]
C8H18NO4PS2 | [MDL Number]
MFCD00055442 | [Molecular Weight]
287.34 | [MOL File]
2275-23-2.mol |
| Safety Data | Back Directory | [Hazard Codes ]
T;N,N,T,Xn,F | [Risk Statements ]
R21:Harmful in contact with skin.
R25:Toxic if swallowed.
R50:Very Toxic to aquatic organisms.
R36:Irritating to the eyes.
R20/21/22:Harmful by inhalation, in contact with skin and if swallowed .
R11:Highly Flammable. | [Safety Statements ]
S36/37:Wear suitable protective clothing and gloves .
S45:In case of accident or if you feel unwell, seek medical advice immediately (show label where possible) .
S61:Avoid release to the environment. Refer to special instructions safety data sheet .
S16:Keep away from sources of ignition-No smoking . | [RIDADR ]
UN 2811 | [WGK Germany ]
2 | [RTECS ]
TF7900000 | [HazardClass ]
6.1(b) | [PackingGroup ]
III | [Hazardous Substances Data]
2275-23-2(Hazardous Substances Data) | [Toxicity]
LD50 oral in rabbit: 160mg/kg |
| Hazard Information | Back Directory | [Description]
Vamidothion is a colorless crystalline substance,. It is readily soluble in
water (4 kg/L) and most organic solvents except aliphatic
hydrocarbons. Log Kow = 0.12. It decomposes in strong
alkaline and acidic media.
| [Uses]
Vamidothion is a phosphorothioic insecticide for apples and potatoes. | [Uses]
Vamidothion is a systemic insecticide used to control Homoptera
in cotton, fruit and rice. | [Definition]
ChEBI: An organic thiophosphate that is N-methyl-2-[(2-sulfanylethyl)sulfanyl]propanamide in which the thiol group has been converted to the corresponding O,O-dimethyl thiophoshate. Formerly used as an inse
ticide and acaricide, it is no longer approved for use within the European Union. | [Pharmacology]
Pyriproxyfen formulations demonstrate persistent efficacy. For example, a water-based 5.3%
pyriproxyfen spot-on formulation applied to cats was
reported to completely prevent the hatching of flea eggs for
at least 46 days after treatment and continued to provide
greater than 96% control until day 60 (57). Because
pyriproxyfen is efficacious at very low concentrations, trace
amounts of the chemical, when transferred from treated
pets to their environments, are sufficient to inhibit the
development of larvae. | [Synthesis]
The synthesis of vamidothion involves a two-step process. The first step is the synthesis of the intermediate, 2-((2-hydroxyethyl)thio)-N-methylpropanamide. The second step is the phosphorylation of this intermediate to yield vamidothion.
Step 1: Synthesis of Synthesis of 2-((2-hydroxyethyl)thio)-N-methylpropanamide (Intermediate 1).
In a round-bottom flask equipped with a magnetic stirrer and a reflux condenser, dissolve
ethyl 2-mercaptopropionate (1 equivalent) in a suitable solvent such as ethanol.
Add sodium ethoxide (1.1 equivalents) to the solution and stir for 15 minutes at room
temperature.
To this solution, add 2-chloroethanol (1.2 equivalents) dropwise.
Heat the reaction mixture to reflux for 4-6 hours.
Monitor the reaction progress by Thin Layer Chromatography (TLC).
After completion, cool the reaction mixture to room temperature and remove the solvent
under reduced pressure.
Extract the crude product with a suitable organic solvent (e.g., ethyl acetate) and wash
with brine.
Dry the organic layer over anhydrous sodium sulfate and concentrate to obtain the crude
ethyl 2-((2-hydroxyethyl)thio)propanoate. Dissolve the crude ethyl 2-((2-hydroxyethyl)thio)propanoate in an excess of a 40%
aqueous solution of methylamine.
Stir the mixture at room temperature for 24-48 hours.
After completion, extract the product with dichloromethane.
Wash the organic layer with water and brine.
Dry the organic layer over anhydrous sodium sulfate and concentrate under reduced pressure to yield the crude 2-((2-hydroxyethyl)thio)-N-methylpropanamide.
Step 2: Synthesis of Vamidothion
In a three-necked flask equipped with a mechanical stirrer, a dropping funnel, and a
thermometer, dissolve the crude 2-((2-hydroxyethyl)thio)-N-methylpropanamide (1
equivalent) in a suitable anhydrous solvent (e.g., toluene) under a nitrogen atmosphere.
Cool the solution to 0-5 °C in an ice bath.
Add a base such as triethylamine (1.2 equivalents) to the solution.
Slowly add O,O-dimethylphosphorochloridothioate (1.1 equivalents) dropwise, maintaining
the temperature below 10 °C.
After the addition is complete, allow the reaction mixture to stir at room temperature for 12
16 hours.
Upon completion, filter the reaction mixture to remove the triethylamine hydrochloride salt.
Wash the filtrate with a saturated solution of sodium bicarbonate and then with brine.
Dry the organic layer over anhydrous sodium sulfate and concentrate under reduced
pressure to obtain crude vamidothion.
| [Metabolic pathway]
Vamidothion is mainly metabolised via oxidation to its sulfoxide; further
oxidation to the corresponding sulfone has been observed in houseflies
but occurs much less readily than with other thioether-containing
organophosphates (e.g. phorate). The sulfoxide is then hydrolysed via
P-S and C-S bond cleavage to give the thiol or hydroxyl derivatives and
dimethyl phosphate and O,O-dimethyl phosphorothioate respectively.
O-Demethylation apparently occurs as a major degradation process
in plants but has not been observed in soil or in animals. N-Demethylation
and hydrolysis to the corresponding carboxylic acid, such as
occurs with dimethoate, does not apparently happen in the case of
vamidothion. | [Degradation]
Vamidothion is decomposed in strongly acidic or alkaline media
(PM). Barceld et al. (1993) examined the photolysis of vamidothion in
water containing 2-4% methanol and 5% acetone as a photosensitiser
irradiated by a xenon arc (suntest) lamp. Metabolites were analysed
and characterised by HPLC, thermospray MS and UV (diode array)
spectra. The main degradation product identified was vamidothion
sulfoxide (2). This product of vamidothion photolysis is shown in
Scheme 1. | [Toxicity evaluation]
The acute oral
LD50 for rats is 64–105 mg/kg. Inhalation LC50 (4 h) for
rats is 1.73 mg/L air. ADI is 8 μg/kg b.w. |
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