Acephate(link:https://www.bloomtechz.com/synthetic-chemical/api-researching-only/acephate-powder-cas-30560-19-1.html) is a pesticide with a long history of use in organic phosphorus pesticides. Its characteristic is that it is an endothermic insecticide with gastric toxicity and contact killing effects, and can kill eggs. It has a certain fumigation effect and is a slow-acting insecticide. Its basic insecticidal principle is to inhibit the insect acetylcholine acetate enzyme. Suitable for vegetables, tobacco, fruit trees, cotton, citrus, rice, and wheat, to prevent and control various chewing and sucking mouthparts pests and pythons. If mixed with pesticides such as carbaryl and dimethoate, it has a synergistic effect and can extend the shelf life.
Method 1: A simple, high yield, low-cost, and high-purity method for preparing acephate; It can overcome the neutralization process required for separating acetic acid, reduce the decomposition loss of acetylmethylamine caused by neutralization, and do not require a large amount of organic solvent extraction process and generate a large amount of wastewater. The technical solution includes the following synthesis reaction process:
(1) Using ethylene ketone and O, O-dimethylthiophosphoramide as raw materials, under the conditions of acylation catalyst and organic solvent, ethylene ketone undergoes acetylation reaction with O, O-dimethylthiophosphoramide to obtain acetylated O, O-dimethylthiophosphoramide; Among them, the mass ratio of ethylene ketone to O, O-dimethylthiophosphoramide is (0.15-0.40): 1;
(2) React acetylated O, O-dimethylthiophosphoramide under isomerization catalyst conditions to prepare acetomethamidophos solution;
(3) Acetylmethamidophos solution was crystallized, solid-liquid separated, and dried to prepare Acetylmethamidophos raw powder.
The chemical reaction equation is as follows:
Method 2:
The raw materials for producing acephate include methyl chloride, ammonia, dichloroethane, ethylene glycol, and dimethyl sulfate vinegar. Obtained through reaction steps such as amination, acylation, and isomerization.
1. Amination:
Add methyl chloride and corresponding proportional amount of dichloroethane horizontally into the amination kettle from the high level metering, and start the stirring and freezing brine. When the temperature in the kettle drops to 15C, slowly drip nitrogen water into the kettle from the high level metering tank of ammonia water, and control the temperature in the kettle at 35-40% C for 35.40 min. After adding ammonia water, adjust the frozen brine to reduce the temperature in the kettle to 20-23C. Maintain the temperature and stir for 30-35 minutes, then add 6L of water. After stirring for 2-3 minutes, stop stirring and pump the material into the amination separator for stratification. After 30 minutes, place the organic phase in the receiving tank for metering. This organic phase is the amine compound with solvent (0.0 dimethyl thiophosphoramide).
2. Acylation:
(1) Acetic anhydride method: Put the amine with solvent into the acylation kettle from the high level measuring tank, start stirring, then add acetic anhydride into the acylation kettle from the high level measuring tank of acetic anhydride, and then turn on frozen brine. When the temperature in the kettle drops to 10 ° C, slowly add concentrated sulfuric acid from the high level measuring tank into the reaction kettle. After adding sulfuric acid, turn on air pressure, discharge the frozen brine from the jacket, and slowly heat it with steam to raise the temperature in the kettle to 55-60 ° C, Maintain the reaction for 50 minutes, complete the reaction, and then lower the temperature inside the kettle to 10C. Add chlorine water dropwise from the high level tank of ammonia water to neutralize the acid generated by the reaction, and neutralize it to a pH value of 7-8. During the neutralization process, the temperature should be controlled below 30 ° C. After neutralization, the material should be pumped into a separator for static separation, and the lower organic phase should be separated into the crude acylate storage tank. Then, it should be pumped into the distillation kettle for vacuum distillation and desorption (vacuum degree 86.kPa, 70C, 15-20 minutes), The acylated compound (0,0-dimethyl-N-yl thiophosphoramide) is obtained.
(2) Acetyl chloride method: Place the amine compound with solvent into the acylation kettle from a high-level measuring tank, start stirring, and add acetyl chloride from the high-level measuring tank of ethyl chloride. Then slowly raise the temperature in the reactor to 50 ° C, maintain the temperature for 2 hours, and react more. Reduce the temperature in the reactor to 10 ° C, and then slowly add nitrogen water from the ammonia water high-level measuring tank to neutralize the acid generated by the reaction. Neutralize it to a pH value of 7. During the neutralization process, the temperature in the reactor should be controlled below 30 ° C. After neutralization, add an appropriate amount of water. Dissolve the plating salt generated during the neutralization process, stir for 2-3 minutes, and extract the material to the separator for static separation. Separate the lower organic phase and extract it into a distillation kettle for vacuum desorption (vacuum degree 86.7kPa, 70C, 15-20min) to obtain the compound. The acylation reaction using acetic anhydride or acetyl chloride as the acylating agent can achieve good results.
3. Isomerization:
Put a quantitative amount of acylated substance into the isomerization kettle from the high-level metering tank of acylated substance, start stirring, and then add dimethyl sulfate vinegar proportionally to the isomerization kettle from the high-level metering tank of dimethyl sulfate vinegar. Slowly raise the temperature to 65-70 ° C, maintain the temperature for 2 hours, and discharge to obtain acephate crude oil. For each production of 1 ton of 50% concentration crude oil, the following raw materials are consumed: 1953 kg of methanol (98%), 1660 kg of triple phosphated phosphorus (98%), 120 kg of caustic soda (30%), 3220 kg of dimethyl sulfate (98%), 2450 kg of ammonia (18%), 315 kg of sulfur (98%), 295 kg of acetic acid (98%), 1700 kg of aminated KO (40%), 490 kg of ethylene (69%), and 250 kg of sulfurized (industrial) dichlorane (98%).
Method 3:
Using dimethyl thiophosphate chloride as the raw material, under stirring, amination is carried out with ammonia water, followed by acetylation with acetic anhydride. Acetylation is carried out in the presence of sulfuric acid. During the acetylation process, a portion of the acetic anhydride is converted into acetic acid, which is then neutralized with ammonia. Acetyl chloride can also be used as an acylating agent. After acylation, the solution is left to stand and organically mixed in the lower layer. After separation, dimethyl sulfate is used for isomerization, followed by vacuum distillation to purify the product, vacuum concentration, and crystallization to obtain acephate.
[ 1 ] : Acephate
Method 4:
1. First isomerization followed by acylation. First, in the presence of a small amount of dimethyl sulfate, 0, 0-dimethylthiotenamide is heated for isomerization to generate O, S-dimethylthiotenamide, which then reacts with ethylene or acetyl chloride to produce acephate
2. Firstly, acylation followed by isomerization involves the reaction of 0,0-dimethylthioacetamide with a cooling agent in a solvent of di-ethane or benzene. Commonly used acylating agents include acetic acid+zinc trichloride, vinegar paste, acetyl chloride, vinyl ketone, etc. The cooling reaction generates O, 0-dimethyl-N-ethylthiotenamide, which is then heated and isomerized into ethyl methamidophos in the presence of a small amount of dimethyl sulfate.
3. By using new catalysts and special crystalline solvents, high-purity raw materials can be prepared. The process involves adding 200g of methamidophos crude oil to a reaction flask, stirring and heating to the reaction temperature. Under the action of the catalyst, acylating agent acetic acid is added dropwise, and the reaction temperature is controlled. After dropwise addition, the crude crude oil of methamidophos is incubated for several hours, and then neutralized and extracted to separate the organic and aqueous phases, Organic phase purification of acephate refined crude oil is carried out by adding solvent A and crystal forming additives, slowly stirring, cooling, crystallization, filtration, and rinsing to obtain the finished product. After processing the mother liquor, qualified finished products can be recovered, with a total product yield of>78% and a content of 298.0%.