A method for synthesizing high-content solid technical grade phosmet.

Abstract

This invention relates to chemical synthesis, specifically a method for preparing high-content solid sparganum technical. 2-chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide is reacted with an acid-binding agent and a phase-transfer catalyst under solvent conditions, followed by the addition of methyl sulfide to obtain sparganum technical. This invention uses methyl sulfide to directly synthesize solid sparganum technical, eliminating the step of preparing ammonium methyl sulfide salts, shortening the process, and avoiding the generation of ammonium chloride salts and ammonia nitrogen in the technical wastewater. The condensation step of this invention, using methyl sulfide to directly synthesize solid sparganum technical, achieves a single-step yield of 96%, which is more than 2% higher than existing technologies, and the sparganum technical content reaches 97%.

Description

Technical Field

[0001] This invention relates to chemical synthesis, specifically a method for preparing high-content solid barnyardgrass technical. Background Technology

[0002] S-4-chloro-isopropylphenylcarbamoylmethyl-O,O-dimethyl dithiophosphate is an organophosphate selective systemic herbicide mainly used in rice paddies to control annual grasses and sedges. Its chemical name is S-4-chloro-isopropylphenylcarbamoylmethyl-O,O-dimethyl dithiophosphate. The technical grade is a yellow or light brown powder with a melting point of 47–50°C. It is readily soluble in acetone, chloroform, toluene, etc., and soluble in benzene, ethanol, ethyl acetate, dichloromethane, etc. Its formulations are brown liquids with a phosphate ester odor.

[0003] Currently, there are three main routes for preparing sparphos. One route involves preparing ammonium methyl sulfide salt via reaction of methyl sulfide and ammonia, followed by filtration and drying to obtain solid ammonium methyl sulfide salt. Another route uses p-chloronitrobenzene as a starting material, reducing it to p-chloroaniline, then alkylating it to prepare the intermediate 4-chloro-N-isopropylaniline, followed by acylation to prepare the intermediate acylated product (2-chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide), and finally condensing the intermediate acylated product with ammonium methyl sulfide salt to obtain the technical grade sparphos.

[0004]

[0005] The drawbacks of existing technologies are that the synthesis of the technical material involves the use of ammonia gas in the preparation of methyl sulfide ammonium salt, and the drying process of methyl sulfide ammonium salt generates a large amount of odorous waste gas, making the process cumbersome. Furthermore, the wastewater from the technical material of sparphos contains a large amount of ammonium chloride, making wastewater treatment complex. Additionally, the existing methods produce sparphos paste-like technical material with low content and low yield. Summary of the Invention

[0006] The purpose of this invention is to provide a simple and environmentally friendly method for preparing barnyardgrass technical.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for synthesizing high-content solid technical grade phosmet involves adding an acid-binding agent and a phase-transfer catalyst to 2-chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide under solvent conditions, followed by the addition of a methyl sulfide to the system to obtain the technical grade phosmet; the reaction formula is as follows:

[0009]

[0010] Further, 2-chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide was added to a solvent with an acid-binding agent and a phase transfer catalyst, and the temperature was raised to 40-50°C. Methyl sulfide was then added to the system and kept at this temperature for 2-4 hours to obtain the technical grade of sparphos.

[0011] The crude sparphos technical obtained from the reaction is heated, washed with water to separate the layers, the aqueous layer is collected, the solvent is evaporated under reduced pressure to obtain crude sparphos, and heptane is added for recrystallization to obtain high-content solid sparphos technical.

[0012] Specifically, the crude sparphos technical obtained from the reaction is heated to 60-65℃, washed with water to separate the layers, the aqueous layer is collected, and the oil layer is desolventized under reduced pressure. The endpoint is -0.099MPa, 85℃, and the solvent is evaporated to obtain crude sparphos. Heptane is added for recrystallization, and the crystallization endpoint is 0-5℃, thus obtaining high-content solid sparphos technical.

[0013] The molar ratio of 2-chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide to methyl sulfide is 1:1.05 to 1:1.1.

[0014] The 2-chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide is a toluene solution of 2-chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide, after removing the toluene, it is ready for use;

[0015] The toluene removal process involves desolvation under reduced pressure. An acetamide-toluene solution is added at 20–40°C, and the pressure is reduced to below 1333 Pa. Desolvation is then initiated by raising the temperature, with the final temperature being 95°C, yielding crude acetamide.

[0016] The solvent is one or more of toluene, chloroform, and dichloromethane; wherein the mass ratio of 2-chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide to the solvent is 1:1 to 1:5.

[0017] Preferably, the solvent is toluene or dichloromethane.

[0018] The phase transfer catalyst is one or more of tetrabutylammonium bromide, tetrabutylammonium sulfate, tetrabutylammonium chloride, benzyltriethylammonium chloride, tetrabutylammonium hydrogen sulfate, trioctylmethylammonium chloride, dodecyltrimethylammonium chloride, and tetradecyltrimethylammonium chloride; wherein the mass ratio of 2-chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide to the phase transfer catalyst is 1:0.005 to 1:0.01.

[0019] The acid-binding agent is one or more of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, solid sodium hydroxide, solid potassium hydroxide, sodium amino acid, sodium methoxide, and sodium ethoxide; wherein the molar ratio of 2-chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide to the acid-binding agent is 1:1 to 1:2.

[0020] Preferably, the acid-binding agent is sodium carbonate, potassium carbonate, or sodium bicarbonate.

[0021] The reaction principle of this invention is as follows: This invention uses methyl sulfide as a nucleophile to undergo a nucleophilic addition reaction with acylate.

[0022] Advantages of this invention:

[0023] This invention addresses existing technologies involving the condensation step of phosmet technical, directly synthesizing solid phosmet technical using methyl sulfide. This eliminates the step of preparing ammonium methyl sulfide salts, shortening the process. Furthermore, this invention avoids the generation of ammonium chloride salts and ammonia nitrogen in the technical wastewater. The condensation step of this invention, using methyl sulfide to directly synthesize solid phosmet technical, achieves a single-step yield of 96%, exceeding existing technologies by more than 2%, and a phosmet technical content of 97%. Detailed Implementation

[0024] The following examples further illustrate specific embodiments of the present invention. It should be noted that the specific embodiments described herein are merely for illustration and explanation and are not intended to limit the scope of the present invention.

[0025] This invention uses methyl sulfide as a starting material and directly produces solid technical grade phosmet without the methyl sulfide ammonium salt process, resulting in a shorter synthesis method. It reduces ammonia nitrogen emissions at the source and eliminates ammonium chloride in the wastewater, making it more environmentally friendly. This method is suitable for industrial application.

[0026] Example 1

[0027] 115 g (0.2 mol) of 2-chloro-N-(4-chlorophenyl)-N-isopropylacetamide toluene solution was added sequentially to a 1000 ml four-necked flask. Mechanical stirring was started, and the pressure was reduced to 1000–1333 Pa using a circulating water pump. The solution was then heated to remove the solvent, with the endpoint temperature at 95 °C. After solvent removal, the temperature was lowered to below 55 °C, and 100 g of toluene, 21.4 g (0.2 mol) of sodium carbonate, and 0.65 g (0.002 mol) of tetrabutylammonium bromide were added. The temperature was raised to 40–45 °C, and 35.3 g (0.21 mol) of methyl sulfide was added dropwise. The mixture was kept at 45 °C for 2 hours, and the reaction was complete. 300 g of water and 100 g of toluene were added, and the temperature was raised to 60–65 °C. The mixture was stirred for 0.5 hours and allowed to stand for 0.5 hours to separate the layers, yielding a phosmet toluene solution. The phosmet toluene solution was then removed under negative pressure, with the endpoint pressure less than 133 Pa and the endpoint temperature at 85 °C. The temperature was lowered to 60℃, 60g of heptane was added, and the temperature was further lowered to 5℃ and maintained for 4 hours to completely precipitate sparphos. The mixture was filtered and washed with 10g of heptane. The filter cake contained sparphos. The filter cake was dried to obtain 72.7g of dried sparphos solid technical grade. The HPLC quantitative analysis showed a purity of 97.2%, and the calculated yield was 96.1%.

[0028] Example 2

[0029] Add 1144.8 g (2 mol) of 2-chloro-N-(4-chlorophenyl)-N-isopropylacetamide toluene solution to a 5000 ml four-necked flask. Start mechanical stirring and desolvate under reduced pressure. The desolvation endpoint pressure is below 1333 Pa, and the endpoint temperature is 95 °C. After desolvation, cool to below 55 °C and add 1000 g of dichloromethane, 254.6 g (3 mol) of sodium bicarbonate, and 5.2 g (0.015 mol) of tetrabutylammonium bisulfate. While stirring, raise the temperature to 40–50 °C and add 370.2 g (2.2 mol) of methyl sulfide. Maintain the temperature at 50 °C for 2 hours to complete the reaction. Add 1000 g of water, raise the temperature to 60–65 °C, stir for 0.5 hours, and let stand for 0.5 hours to obtain a dichloromethane solution of sphagnum molybdate. Desolvate the dichloromethane solution of sphagnum molybdate under negative pressure. The endpoint pressure is less than 133 Pa, and the endpoint temperature is 85 °C. The temperature was lowered to 60℃, 600g of heptane was added, and the temperature was further lowered to 10℃ and maintained for 4 hours to completely precipitate sparphos. The mixture was filtered and washed with 100g of heptane; the filter cake contained sparphos. The filter cake was dried to obtain 726.6g of dried sparphos solid technical grade, with a purity of 97.1% determined by HPLC and a calculated yield of 95.9%.

[0030] Example 3

[0031] 1145 kg (2 kmol) of 2-chloro-N-(4-chlorophenyl)-N-isopropylacetamide toluene solution was added to a 3000 L reactor. The reactor was stirred, and solvent removal was carried out under reduced pressure. The solvent removal endpoint pressure was below 1333 Pa, and the endpoint temperature was 95 °C. After solvent removal, the temperature was lowered to below 55 °C, and 1000 kg of toluene, 268 kg (2.5 kmol) of sodium carbonate, and 5 kg (0.015 kmol) of tetrabutylammonium bisulfate were added. The reactor temperature was raised to 45–50 °C, and 353 kg (2.1 kmol) of methyl sulfide was added dropwise. The mixture was kept at 50 °C for 2 hours, and the reaction was completed. The mixture was discharged into a 6300 L reactor, and 3000 kg of water and 1000 g of toluene were added. The temperature was raised to 60–65 °C, and the mixture was stirred for 0.5 hours. After standing for 0.5 hours, the mixture was separated into layers to obtain a phosmet toluene solution. Negative pressure was used to desolvate the toluene solution of sparphos, with an endpoint pressure less than 133 Pa and an endpoint temperature of 85℃. The solution was cooled to 60℃, and 600 kg of heptane was added. The temperature was further lowered to 10℃ and maintained for 4 hours to completely precipitate sparphos. The solution was filtered and washed with 100 kg of heptane. The filter cake contained sparphos. The filter cake was dried to obtain 726.6 kg of dried sparphos solid technical grade. The HPLC quantitative analysis showed a purity of 97.3%, and the calculated yield was 96.1%.

[0032] Comparative Example 1

[0033] The difference from Example 1 is that the acid-binding agent is triethylamine, and the other conditions are the same as in Example 1. 57.9g of dried barnyardgrass solid technical grade was obtained, with a barnyardgrass solid technical grade yield of 69.1% and a barnyardgrass solid technical grade content of 87.8%.

[0034] Comparative Example 2

[0035] To a 1000ml four-necked flask, add 115g (0.2mol) of 2-chloro-N-(4-chlorophenyl)-N-isopropylacetamide toluene solution, 21.4g (0.2mol) of sodium carbonate, and 0.65g (0.002mol) of tetrabutylammonium bromide. Start mechanical stirring and heat to 55–60℃. Add 35.3g (0.21mol) of methyl sulfide dropwise and maintain the temperature at 60℃ for 2 hours until the reaction is complete. Add 300g of water and 100g of toluene, heat to 60–65℃, stir for 0.5 hours, and let stand for 0.5 hours to obtain a toluene solution containing sparphosphatidylcholine. Desolvate the sparphosphatidylcholine solution under negative pressure; the endpoint pressure is less than 133Pa, and the endpoint temperature is 85℃. Cool to 60℃, add 60g of heptane, and continue cooling to 5℃. Maintain the temperature for 4 hours to completely precipitate sparphosphatidylcholine. The sample was filtered and washed with 10g of heptane. The filter cake was sparphosphide. The filter cake was dried to obtain 55.7g of dried sparphosphide solid technical grade. The content was 86.5% by HPLC and the yield was calculated to be 65.5%.

[0036] As can be seen from the above examples and comparative examples, changes in reaction conditions all lead to a decrease in yield. Comparative Example 1 used triethylamine as an acid-binding agent, which resulted in the formation of more tar. The refining step could not completely remove the tar, and the tar and sparphos technical grade exhibited a certain degree of miscibility, leading to low yield and low content. Comparative Example 2 used a reaction temperature of 55–60°C, higher than Example 1, but the yield and content of the dried sparphos solid technical grade were lower than in Example 1. This is likely because the increased reaction temperature caused the thermal stability of methyl sulfide to decompose, producing tar. The tar and sparphos technical grade exhibited a certain degree of miscibility, resulting in low yield and low content. Therefore, only under specific reaction conditions can the method of directly synthesizing sparphos solid technical grade using methyl sulfide achieve a single-step yield of 96% and a sparphos technical grade content of 97%.

Claims

1. A method for synthesizing a high-content solid technical grade of barnyardgrass, characterized in that: 2-Chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide was reacted with an acid-binding agent and a catalyst in a solvent. The mixture was heated to 40-50°C, and methyl sulfide was added to the system and kept at this temperature for 2-4 hours to obtain sparphos technical grade. The crude sparphos technical grade was heated, washed with water to separate the layers, and the oil layer was collected. The solvent was evaporated from the oil layer under reduced pressure to obtain crude sparphos. Heptane was added and recrystallized to obtain high-content solid sparphos technical grade. The reaction formula is: ; The acid-binding agent is sodium carbonate or sodium bicarbonate; the molar ratio of 2-chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide to the acid-binding agent is 1:1 to 1:2; The catalyst is tetrabutylammonium bromide or tetrabutylammonium hydrogen sulfate; wherein the mass ratio of 2-chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide to the catalyst is 1:0.005 to 1:0.

01.

2. The method for synthesizing high-content solid technical grade phosmet according to claim 1, characterized in that: The molar ratio of 2-chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide to methyl sulfide is 1:1.05 to 1:1.

1.

3. The method for synthesizing high-content solid technical grade phosmet according to claim 1, characterized in that: The 2-chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide is a toluene solution of 2-chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide, after which the toluene is removed, and it is ready for use.

4. The method for synthesizing high-content solid technical grade phosmet according to claim 1, characterized in that: The solvent is one or more of toluene, chloroform, and dichloromethane; wherein the mass ratio of 2-chloro-N-(4-chlorophenyl)-N-(isopropyl)acetamide to the solvent is 1:1 to 1:5.

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