Two preparation methods of O,O-dimethylthiophosphoramide_Industrial additives

Background and overview^[1]

O,O-dimethylthiophosphoramide is an important pesticide intermediate, commonly known as spermine. It can be used to synthesize methamidophos, acephate, chlormethoate and other pesticides. Very versatile.

Preparation^[1-2]

Report 1,

Put 210 kilograms of water and 1050 kilograms of O,O’-dimethylphosphorothioate chloride (content 92.5%) into a 3000-liter glass-lined reaction pot. Start the stirring slurry at a temperature of 15°C and directly pass in liquid ammonia. The ammonia flow pressure is 0.15kPa, and the ammonia ratio is controlled to 30%. When the pH value of the reaction solution reaches 8-9, the ammonia flow is stopped until the end point. The ammonia reaction time is 2 hours, then the material is discharged and centrifuged, and the solid ammonium chloride is rinsed with cold water at 0-5°C; the liquid part is the organic phase mainly composed of O,O’-dimethylthiophosphoramide and the ammonium chloride solution. A mixed liquid formed from the aqueous phase. The mixed liquid is transferred to the separator for separation, and the water phase is transferred to the reaction pot to continue production and use. After the cycle is supersaturated, ammonium chloride solid Rohm and Haas resin is recovered through filtration, and the water phase continues to be produced and used. The organic phase is converted into spermamide after post-treatment. The yield of O,O’-dimethylthiophosphoramide is 98%, and the content is more than 98.5% (measured by GC, that is, gas chromatography).

Report 2,

Put O,O-dimethylthiophosphoryl chloride with a concentration of 98% into the first-level amination kettle and perform heat exchange with the frozen brine in the jacket of the first-level amination kettle, so that the concentration is 98%. The temperature of the O,O-dimethylthiophosphoryl chloride raw material drops to 5°C. Connect the liquid ammonia tank containing liquid ammonia to the ammonia gasifier through a pipeline. Open the ammonia gasifier valve and the ammonia gas passes through the first stage. The distributor in the amination kettle is introduced into the O,O-dimethylthiophosphoryl chloride liquid. The ammonia flow rate is controlled at 120kg/h and the pressure is controlled at 0.05MPa. Stirring is carried out while introducing ammonia gas. The stirring speed is 80～130r/min, the reaction temperature in the primary amination kettle is controlled at 20°C, the molar ratio of O,O-dimethylphosphorothioate chloride and ammonia is 1:1.05; O with a concentration of 98%, O-Dimethylthiophosphonyl chloride is placed into the secondary amination kettle and heat exchanges with the chilled brine in the jacket of the secondary amination kettle, so that the concentration of O,O-dimethylthiophosphoryl chloride is 98%. The temperature of the acid chloride raw material was lowered to 5°C, and the excess ammonia in the primary amination kettle was introduced into the 98% O,O-dimethylthiophosphoryl chloride solution in the secondary amination kettle through an induced draft fan. reaction, the remaining ammonia gas in the secondary amination kettle is passed into the spray tower with aqueous solution for spray absorption treatment; when the ammonia feed amount of the primary amination kettle is 0.7mol, open the primary amination kettle The valve at the bottom of the kettle allows the mixed materials in the primary amination kettle to flow from the bottom of the kettle into the automatic centrifuge for continuous centrifugation. The centrifugal speed is 2000~3000r/min. After centrifugation, the upper liquid is pumped into the primary amination kettle through a liquid pump. The reaction proceeds again in the kettle; when the mass fraction of O,O-dimethylthiophosphoryl chloride in the primary amination kettle is less than 0.1%, open the bottom valve of the primary amination kettle to allow the hand feeling in the primary amination kettle to The agent mixture flows from the bottom of the kettle into an automatic centrifuge for continuous centrifugation. The filter cake after centrifugation is the crude ammonium chloride. The crude ammonium chloride is washed with methanol for 30 minutes and then is discharged, packaged and recycled. After washing the crude ammonium chloride, The filtrate is treated by a methanol removal distillation system and then recycled and reused. The liquid obtained after centrifugation of the mixed materials in the primary amination kettle is O,O-dimethylthiophosphoramide.