Rapid synthesis method of propanil

Abstract

The invention provides a rapid synthesis method of propanil, and relates to the technical field of pesticide chemical industry. According to the synthetic method, an organic solvent and a catalyst do not need to be additionally added, and efficient reaction in a propionic acid system can be realized by controlling the technical scheme of adding propionic acid in batches; the reaction time of the system is shortened to be within 8 hours from general 30 hours under the condition of no additional organic solvent or catalyst, and economic, green and efficient industrial production of propanil is realized.

Description

Technical Field

[0001] This invention relates to the field of pesticide chemical technology, specifically to a rapid synthesis method for propargite. Background Technology

[0002] Propanil is an amide herbicide mainly used in direct-seeded rice paddies, transplanted rice paddies, and rice seedling beds for the control of annual weeds in rice and transplanted rice fields. It is effective against weeds such as barnyard grass, foxtail grass, crabgrass, water purslane, and duckweed. Propanil's mechanism of action is multifaceted; it not only disrupts photosynthesis but also inhibits respiration and oxidative phosphorylation, interferes with nucleic acid and protein synthesis, damages cell membranes, and leads to water metabolism disorders, causing rapid dehydration and death. However, arylcarboxyamitinase in rice can rapidly decompose propanil into non-toxic substances, making it safe for rice. Furthermore, propanil decomposes and becomes ineffective upon contact with soil.

[0003] Currently, most patents for the synthesis of propargite utilize catalytic systems. In 2022, Inner Mongolia Laike Crop Protection Co., Ltd. published a method for the catalytic synthesis of propargite, patent CN 115181033 A. This method involves heating solvents chlorobenzene, 3,4-dichloroaniline, propionic acid, and a catalyst until the materials are completely dissolved, followed by the slow addition of phosphorus trichloride to obtain a synthesis solution. The solution is then purified through separation to produce the propargite product. While this method allows for rapid one-step synthesis of propargite, the use of a large amount of phosphorus trichloride as a catalyst results in a high level of impurities in the product, affecting its content and effectiveness. Furthermore, it generates a large amount of phosphorus-containing wastewater, leading to high treatment costs. Therefore, this method is unsuitable for industrial production.

[0004] Patent CN 114230478 A discloses a catalytic method that uses a mixture of molecular sieve and phosphine / nitrogen-containing compounds as catalysts, which easily introduces phosphine / nitrogen-containing impurities and is difficult to handle. Patent CN 111320549A introduces toluene solvent, which increases the operation process and production costs. Patent CN 113402410A introduces propionic anhydride as a desiccant, which requires a large amount and is expensive, making it unsuitable for industrial production. The method disclosed in patent CN119080630A introduces both catalyst and reaction solvent, which increases the production process and improves the production cost of the product.

[0005] Another method is a multi-step synthesis, such as patent CN 108752229 A, which uses chlorobenzene as a raw material. First, chlorobenzene undergoes an acylation reaction with propionyl chloride to produce p-chlorophenylacetone. Then, p-chlorophenylacetone undergoes a condensation reaction with hydroxylamine hydrochloride to produce 1-(4-chlorophenyl)-1-propanone oxime. 1-(4-chlorophenyl)-1-propanone oxime then undergoes a rearrangement reaction under acidic conditions, and finally, after chlorination, the product, dimethicone, is obtained. This method involves many steps, is overly complex, difficult to industrialize, and has high costs.

[0006] Currently, the mainstream industrial production process involves a direct high-temperature reflux reaction of propionic acid with 3,4-dichloroaniline, followed by a sustained-temperature reaction. While this method is simple to operate, it suffers from long reflux times and high energy consumption in the early stages, slow reaction speed in the later stages, and difficulty in quickly extracting the water produced. The total reaction time is generally over 30 hours.

[0007] Given the current slow synthesis rate of propargite, the long reaction time required, and the complex process, there is an urgent need to develop a method that can rapidly synthesize high-quality propargite. Summary of the Invention

[0008] To overcome the shortcomings of existing technologies, this invention provides a rapid synthesis method for anthelmintic spores.

[0009] The specific technical solution of this invention is as follows:

[0010] A rapid synthesis method for barnyardgrass includes the following steps:

[0011] 1) Weigh out the reaction amounts of 3,4-dichloroaniline and propionic acid, add 3,4-dichloroaniline and part of the propionic acid into the reactor, and heat and stir to react;

[0012] 2) After the reaction solution is heated to the preset temperature, the remaining propionic acid is added dropwise. The reaction is carried out while the temperature is controlled and the mixture is stirred. After the addition is completed, the reaction is kept at the temperature. The azeotropic components are separated during the reaction process.

[0013] 3) After the reaction is complete, the propionic acid is removed by vacuum distillation to obtain the target product, propanil.

[0014] Preferably, the molar ratio of 3,4-dichloroaniline to propionic acid is 1:2.0~3.0, more preferably 1:2.3~2.8, and particularly preferably 1:2.6.

[0015] Preferably, the amount of propionic acid added in step 1 is 1 / 3 to 1 / 2 of the total amount of propionic acid.

[0016] Preferably, the preset heating temperature in steps 1 and 2 is 130~150℃, and more preferably 140~150℃.

[0017] Preferably, the propionic acid addition time in step 2 is controlled to be 3 to 5 hours.

[0018] Preferably, the temperature of the reaction during the addition of propionic acid in step 2 is 150~160℃.

[0019] Preferably, the heat preservation temperature in step 2 is 160~165℃.

[0020] Preferably, the heat preservation reaction time in step 2 is 2 to 3 hours.

[0021] Preferably, the pressure of the vacuum distillation in step 3 is -0.09 to -0.1 MPa, and the temperature is 100 to 120°C.

[0022] The beneficial effects of this invention are:

[0023] The synthesis method of propionic acid in this invention does not require the addition of additional organic solvents and catalysts. The efficient reaction in the propionic acid system can be achieved by controlling the addition of propionic acid in stages. Under the condition of no additional organic solvents and catalysts, the reaction time of the system is reduced from the usual 30 hours to less than 8 hours, realizing the economical, green and efficient industrial production of propionic acid. Detailed Implementation

[0024] The present invention will be further illustrated below through embodiments. It should be understood that the embodiments of the present invention are merely for illustrating the invention and not for limiting the invention. Therefore, simple improvements to the present invention under the premise of the method of the present invention are all within the scope of protection of the present invention.

[0025] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0026] Example 1

[0027] 100.0 g (0.614 mol, 99.5% purity) of 3,4-dichloroaniline and 45.9 g (0.614 mol, 99.0% purity) of propionic acid (1.0 equivalent) were added to a 500 mL reaction flask, and the mixture was heated to 145 °C for 1 hour. Then, 73.5 g of [amount missing] was added dropwise to the reaction flask using a constant pressure dropper. 0.983 mol (purity 99.0%) propionic acid (1.6 equivalents) was added dropwise. The temperature inside the reaction flask was controlled at 150~160℃ during the dropwise addition process, and the dropwise addition time was 3.5 hours. The azeotropic component was collected simultaneously during the dropwise addition. After the dropwise addition was completed, the temperature inside the reaction flask was kept at 160~165℃ for 3 hours. After the temperature was kept at 160℃, the sample was taken for analysis. 0.14% of the raw material 3,4-dichloroaniline remained. The total reaction time was 7.5 hours. After the reaction was completed, the reaction temperature was lowered to 110℃ (±10℃), and the remaining propionic acid was removed under the conditions of -0.09 to -0.1 MPa to obtain the dimethicone compound with a yield of 98.7% and a purity of 99.1%.

[0028] Example 2

[0029] 100.0 g (0.614 mol, 99.5% purity) of 3,4-dichloroaniline and 55.1 g (0.737 mol, 99.0% purity) of propionic acid (1.2 equivalents) were added to a 500 mL reaction flask, and the mixture was heated to 140 °C for 1 hour. Then, 82.6 g of [amount missing] was added dropwise to the reaction flask through a dropping funnel. (1.105 mol, purity 99.0%) propionic acid (1.8 equivalents), the temperature inside the reaction flask was controlled at 150~160℃ during the dropwise addition process, and the azeotropic component was collected simultaneously during the dropwise addition process, with a dropwise addition time of 4 hours; after the dropwise addition was completed, the temperature was kept at 160~165℃ for 3 hours during the holding period; after the holding period was completed, a sample was taken for analysis, and 0.18% of the raw material 3,4-dichloroaniline remained, and the total reaction time was 8 hours; after the reaction was completed, the reaction temperature was lowered to 110℃ (±10℃), and the remaining propionic acid was removed under the conditions of -0.09~-0.1MPa to obtain the dimethicone compound, with a yield of 98.0% and a purity of 98.6%.

[0030] Example 3

[0031] 10.0 kg (61.4 mol, 99.5% purity) of 3,4-dichloroaniline and 3.21 kg (43.0 mol, 99.0% purity) of propionic acid (0.7 equivalents) were added to a 50 L reactor, and the mixture was heated to 145 °C for 1 hour. Then, 5.97 kg (79.8 mol, 99.0% purity) of propionic acid (1.3 equivalents) was added dropwise to the reactor using a syringe pump. The temperature inside the reaction vessel was controlled at 150-160 °C during the addition process, and the addition time was 4 hours. During the dropwise addition, the azeotropic component was collected simultaneously. After the dropwise addition was completed, the mixture was kept at a constant temperature for 3 hours, with the temperature inside the reaction flask controlled at 160~165℃ during the holding period. After the holding period was completed, samples were taken for analysis, and 0.11% of the raw material 3,4-dichloroaniline remained. The total reaction time was 8 hours. After the reaction was completed, the reaction temperature was lowered to 110℃ (±10℃), and the remaining propionic acid was removed under conditions of -0.09 to -0.1 MPa to obtain the dimethicone compound with a yield of 98.5% and a purity of 98.9%.

[0032] Comparative Example 1

[0033] 3,4-Dichloroaniline (162.05 g, 1 mol) and propionic acid (194.4 g, 2.6 mol) were added to a reactor. The temperature was raised, and the reaction system was stirred at 155-165 °C. During the reaction, samples were taken to analyze the remaining amount of 3,4-dichloroaniline. After stirring for 32 hours, 0.17% of 3,4-dichloroaniline remained, and the reaction was terminated. The mixture was then distilled under reduced pressure at -0.09 to -0.1 MPa and 110 °C to obtain the dimethicone compound with a yield of 98.4% and a purity of 97.7%.

Claims

1. A rapid synthesis method for anthelmintic barnyardgrass, characterized in that, Specifically, the steps include the following: 1) Weigh out the reaction amounts of 3,4-dichloroaniline and propionic acid, add 3,4-dichloroaniline and part of the propionic acid into the reactor, and heat and stir to react; 2) After the reaction solution is heated to the preset temperature, the remaining propionic acid is added dropwise. The reaction is carried out while the temperature is controlled and the mixture is stirred. After the addition is completed, the reaction is kept at the temperature. The azeotropic components are separated during the reaction process. 3) After the reaction is complete, the propionic acid is removed by vacuum distillation to obtain the target product, propanil.

2. The method for synthesizing argan oil as described in claim 1, characterized in that, The molar ratio of 3,4-dichloroaniline to propionic acid is 1:2.0~3.

0.

3. The method for synthesizing argan oil as described in claim 1, characterized in that, The amount of propionic acid added in step 1 is 1 / 3 to 1 / 2 of the total amount of propionic acid.

4. The method for synthesizing argan oil as described in claim 1, characterized in that, The preset heating temperature in steps 1 and 2 is 130~150℃.

5. The method for synthesizing argan oil as described in claim 1, characterized in that, The propionic acid addition time in step 2 is controlled to be 3-5 hours.

6. The method for synthesizing argan oil as described in claim 1, characterized in that, The temperature of the reaction during the addition of propionic acid in step 2 is controlled at 150~160℃.

7. The method for synthesizing argan oil as described in claim 1, characterized in that, The insulation temperature in step 2 is 160~165℃.

8. The method for synthesizing argan oil as described in claim 1, characterized in that, The heat preservation reaction time in step 2 is 2 to 3 hours.

9. The method for synthesizing argan oil as described in claim 1, characterized in that, The pressure of vacuum distillation in step 3 is -0.09 to -0.1 MPa, and the temperature is 100 to 120°C.