Метилдихлортиофосфат

Description

Methyl dichlorothiophosphate is an O-methyl ester of phosphodichloridothionic acid, CH₃O–P(=S)Cl₂. An intermediate product in the production of organophosphorus pesticides: the two mobile chlorine atoms of phosphorus are successively replaced by nucleophiles, allowing the collection of unsymmetrical thiophosphates. The compound is classified in the “Intermediate pesticides” section.

Identification

• CAS No.: 2523-94-6
• English name: Methyl dichlorothiophosphate
• Chemical formula: CH3Cl2OPS
• EU number: 219-753-3
• DSSTox ID: DTXSID10179892
• HS code: 2931 90 00 90
• Synonyms: phosphorodichloridothionic acid O-methyl ester, methyl phosphorodichloridothioate, O-methylphosphorodichlorothioate, dichloromethoxyphosphine sulfide, methyl dichlorothionophosphate

Physico-chemical indicators

• Molecular Weight: 164.978681
• Exact weight: 164.98
• Density: 1.4949 g/cm³ at 0 °C
• Boiling point: 70 °C at 40 Torr pressure
• Flash point: 49.9 °C
• Refractive index: 1.519
• Steam pressure: 3.32 mm Hg. Art. at 25 °C
• PSA: 51.13
• XLogP3: 2.9855

Chemical behavior and application

The phosphorus atom carries thionic sulfur, a methoxy group and two chlorine atoms. P–Cl bonds are easily replaced: by alcohols and alcoholates to form esters, by phenolates to form arylthiophosphates, by amines to form amidothiophosphates. Stepwise substitution allows the introduction of two different residues and the construction of asymmetric structures. It is this scheme that underlies the production of active ingredients of organophosphorus insecticides.

• intermediate product of the synthesis of organophosphorus insecticides and acaricides
• reagent for introducing an O-methylthiophosphoryl moiety into organic molecules
• starting material for amidothiophosphates and mixed esters of thiophosphoric acid
• fine organophosphorus synthesis reagent

Compatibility and Handling

The acid chloride nature of the compound determines the main limitation: contact with water and air moisture leads to hydrolysis with the release of hydrogen chloride. Work is carried out under anhydrous conditions, in a dry inert atmosphere, and corrosion-resistant equipment is selected. The flash point of 49.9 °C classifies the product as a flammable liquid, vapor pressure is 3.32 mmHg. Art. at 25 °C means noticeable volatility - operations are performed under hood.

Safety Information

The GHS hazard classification, H and P statements for this compound are not given in the product data sheet. The handling regime is established according to the supplier's safety data sheet. Practical measures arise from the properties of the substance: as an intermediate product of organophosphorus pesticides, it requires handling according to the rules for substances capable of inhibiting cholinesterase - work under a hood, durable gloves, eye and respiratory protection, avoiding contact with skin. Storage in a cool, dry place, in a sealed container, away from sources of ignition, oxidizing agents, water and alkalis, separate from food materials.