Pirimiphos-methyl synthesis

Yield:29232-93-7 98.6%

Reaction Conditions:

Stage #1:2-diethylamino-4-hydroxy-6-methyl-pyrimidine with potassium carbonate in water;toluene at 78 - 93; for 0.5 h;Green chemistry;
Stage #2:dimethyl chlorothiophosphate at 20;Green chemistry;Solvent;Temperature;

Steps:

1-4
(1) Add 25g (98%, 0.14mol) of 2-diethylamino-6-methyl-4-hydroxypyrimidine to a 500ml four-necked flask equipped with stirring, thermometer, constant pressure dropping funnel and water separator. , 200ml of toluene and 64.5g (29g, 0.21mol) of 45.0% potassium carbonate aqueous solution, stirred and heated to 78°C, dehydrated under reduced pressure under the pressure of 350-450mm Hg, while the constant pressure dropping funnel was filled with fresh toluene to maintain The liquid level of the reaction system remains unchanged until the top temperature rises to 93°C and remains unchanged for half an hour. After analyzing the moisture content of the reaction system to 800ppm, the reaction is completed, the heating is stopped, and the reaction liquid is cooled to 30-40°C.(2) Add 21.5g (99%, 0.133mol) of O,O-dimethyl thiophosphoryl chloride into the constant pressure dropping funnel, and complete the dropwise addition within 4 to 5 hours. After the dropwise addition is completed, continue the insulation reaction for 1 hour. At the end, the temperature is lowered to room temperature, the salt residue is filtered off, and the filtrate is desolvated under reduced pressure at -0.095MPa 37.9 g of 98.6% methyl pyrimidinhos (external standard of liquid chromatograph) was obtained, and the yield was 92.0% (calculated as methyl chloride). Among them, the content of isomethylpyrimidinhos is 0.03%, O,O,S-trimethyl phosphorodithioate 0.05%, O,O,S-trimethyl phosphorothioate 0.05%, O,O,O-trimethyl Methyl phosphorothioate 0.03%, methyl thiotepu is not detected (gas chromatography internal standard).

References:

CN112358501, 2021, a Location in patent:Paragraph 0037-0052

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