A continuous process and apparatus for the preparation of diuron

Abstract

The application provides a continuous preparation method and a preparation system of diuron, wherein the preparation method comprises the following steps: S1, continuously inputting dimethylamine N,N-dimethylaminocarbamate and 3,4-dichlorophenyl isocyanate solution into a reactor 1 under normal temperature and pressure respectively, controlling the jacket temperature of the reactor 1, and carrying out addition reaction of the two materials in the reactor 1 to generate diuron and byproduct carbon dioxide; S2, carrying out gas-liquid separation of the material obtained in the reaction in the step S1 in a gas-liquid separator 2 to obtain a mixture of diuron and solvent; and S3, carrying out solid-liquid separation on the mixture obtained in the step S2 to obtain diuron solid and solvent. The application has the advantages of continuous production, high efficiency, simplicity, near-zero emission, mild reaction condition and the like, the production efficiency is improved, the safety risk is reduced, the product yield reaches more than 96%, and the purity reaches more than 98%.

Description

Technical Field

[0001] This invention relates to the field of pesticide preparation, and in particular to a continuous preparation method and apparatus for diuron. Background Technology

[0002] Diuron, developed by DuPont, is a substituted urea herbicide. It is a selective systemic herbicide that can be absorbed by the roots and leaves of plants, inhibiting the Hill reaction in photosynthesis. It is effective against most annual and perennial weeds, and its efficacy can last for more than 60 days. Currently, the main method for preparing diuron is the relatively mature isocyanate synthesis method. However, with the expansion of production efficiency and increasing environmental protection requirements, the traditional preparation process has shown its shortcomings.

[0003] For example, Chinese patent CN108863852 discloses a method for preparing diuron, which involves placing dimethylamine aqueous solution and toluene into a reaction vessel, adding 3,4-dichlorophenyl isocyanate dropwise, and controlling the pH value as the endpoint. After maintaining the reaction temperature, diuron solid is separated. This preparation method using dimethylamine aqueous solution as raw material generates a large amount of alkaline wastewater with high ammonia nitrogen values, making it unusable and placing significant pressure on environmental protection. During the reaction, the amount of 3,4-dichlorophenyl isocyanate added needs to be controlled by judging the pH endpoint of the reaction system. Sampling is prone to VOC emissions, polluting the environment and negatively impacting the health of production operators. Furthermore, when the system has a high water content, 3,4-dichlorophenyl isocyanate is easily hydrolyzed, producing the insoluble byproduct N,N'-bis(3,4-dichlorophenyl)urea.

[0004] In addition, Chinese patent CN104496855 discloses another method for synthesizing diuron. Under a pressure of 0.2-2 MPa, liquid dimethylamine is added dropwise to a 3,4-dichlorophenyl isocyanate solution, and the reaction is carried out under this pressure. The molar ratio of 3,4-dichlorophenyl isocyanate to liquid dimethylamine is controlled at 1:1.05-1.3. After the reaction, the excess dimethylamine is recovered by heating, and then the reaction solution is cooled and post-treated to obtain diuron. This pressurized reaction method is essentially still an addition reaction between 3,4-dichlorophenyl isocyanate and dimethylamine. Excess dimethylamine has low solubility in the solvent and easily escapes in gaseous form, resulting in low recovery efficiency and resource waste. When dimethylamine is in excess, the reaction system is prone to side reactions in a strongly alkaline environment, making production control difficult. Furthermore, liquid dimethylamine storage tanks are major hazard sources, placing significant risk management pressure on production enterprises.

[0005] The aforementioned method for preparing diuron using aqueous or liquid dimethylamine is typically carried out in a batch reactor during industrial production, resulting in low efficiency, significant resource waste, and complex post-processing steps. In particular, when dimethylamine is introduced into the reaction system in gaseous form, the generated diuron precipitates from the solvent and easily clogs the gas inlet pipe, lacking intrinsic safety. Summary of the Invention

[0006] The technical problem to be solved by the present invention is how to achieve the continuous preparation of diuron. In view of the above-mentioned technical problem, a method for the continuous preparation of diuron is proposed.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing diuron, comprising the following steps:

[0008] S1. Under normal temperature and pressure, dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate solution are continuously added to the reactor in a continuous quantitative addition manner. The dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate solution generate diuron and carbon dioxide by-product in the reactor.

[0009] S2. The material obtained from the reaction in step S1 is fed into a gas-liquid separator in a continuous feeding manner to separate the gas and liquid, and obtain a mixture of diuron and solvent.

[0010] S3. Perform solid-liquid separation on the mixture obtained in step S2 to obtain diuron solid and solvent;

[0011] Furthermore, in step S1, the dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate solutions undergo a continuous static mixing reaction in a reactor.

[0012] Furthermore, the 3,4-dichlorophenyl isocyanate solution in step S1 is composed of 3,4-dichlorophenyl isocyanate and a solvent, wherein the solvent is one of toluene, xylene, chlorobenzene, ethyl acetate, butyl acetate, N-methylpyrrolidone, tetrahydrofuran, and 2-methyltetrahydrofuran.

[0013] Furthermore, the mass concentration of 3,4-dichlorophenyl isocyanate in the 3,4-dichlorophenyl isocyanate solution in step S1 is 5-70%.

[0014] Furthermore, in step S1, the quantitative addition molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine N,N-dimethylcarbamate is between 1:0.5 and 1:0.55.

[0015] Furthermore, the reaction temperature inside the reactor in step S1 is -5 to 65°C.

[0016] Another object of the present invention is to provide a continuous preparation apparatus for diuron, comprising a reactor and a gas-liquid separator, wherein the gas-liquid separator is disposed at the rear end of the reactor;

[0017] The reactor is a continuous static mixing reactor, and the reactor is equipped with a static mixing structure inside.

[0018] Furthermore, the reactor is provided with an inlet A and an outlet B at the front and rear, respectively, and the gas-liquid separator is provided with an inlet C, an outlet D, and a tail gas outlet E. The outlet B of the reactor is connected to the inlet C of the gas-liquid separator. The inlet A is used to add the raw materials dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate solution. The inlet C is used for the product of the reactor to enter. The tail gas outlet E is used to pass the carbon dioxide gas generated by the side reaction into the tail gas system. The outlet D is used to pass the mixture of product diuron and solvent into the separation device to obtain diuron solid and solvent.

[0019] Furthermore, a jacket is provided on the outside of the reactor, which is used to regulate the reaction temperature of the reactor. The temperature of the jacket is -10 to 70°C.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] (1) In the continuous preparation method of diuron of the present invention, dimethylamine N,N-dimethylcarbamate is used as raw material. It is a near-neutral ionic liquid at room temperature and pressure, which is convenient for metering and controlling the reaction endpoint. It has the characteristics of intrinsic safety. During the reaction, a slight excess of dimethylamine N,N-dimethylcarbamate dissolves in the solvent. Therefore, there is no dimethylamine gas emission in the reaction system, which reduces the generation of pollutants in the production and reduces the treatment of subsequent pollutants.

[0022] (2) In the continuous preparation method of diuron of the present invention, a static mixing reactor is used for continuous addition reaction. There are no moving parts inside the reactor, which is safer and more reliable. It realizes efficient and continuous production of diuron, improves production efficiency, and has a lower online liquid holding capacity and higher preparation efficiency compared with the existing technology that uses a batch reactor.

[0023] (3) In the continuous preparation method of diuron of the present invention, the reaction type is a fast reaction with a high conversion rate. The post-processing is simple and no wastewater is generated. The by-product carbon dioxide can be directly recycled for the preparation of dimethylamine N,N-dimethylcarbamate after purification, which reduces energy waste.

[0024] (4) The continuous preparation method of diuron of the present invention has the advantages of continuous operation, high efficiency and simplicity, near-zero emission, mild reaction conditions and no clogging phenomenon. It can effectively shorten the reaction time, improve production efficiency, reduce safety risks, and the product yield can reach more than 96% and the purity can reach more than 98%. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the continuous preparation device for diuron in this invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] like Figure 1 The diagram shows a continuous preparation apparatus for diuron according to the present invention, comprising a reactor 1 and a gas-liquid separator 2, wherein the gas-liquid separator 2 is located at the rear end of the reactor 1; the reactor 1 is a continuous static mixing reactor, and the reactor 1 has a static mixing structure inside. The reactor 1 is provided with an inlet A11 and an outlet B12 at the front and rear, respectively, and the gas-liquid separator 2 is provided with an inlet C21, an outlet D22, and a tail gas outlet E23. The outlet B12 of the reactor 1 is connected to the inlet C21 of the gas-liquid separator 2; the inlet A11 is used to add the raw materials dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate solution; the inlet C21 is used for the product of the reactor 1 to enter; the tail gas outlet E23 is used to pass the carbon dioxide gas generated by the side reaction into the tail gas system; and the outlet D22 is used to pass the mixture of the product diuron and the solvent into the separation device to obtain diuron solid and solvent. In addition, a jacket 13 is provided on the outside of the reactor 1, which is used to regulate the reaction temperature of the reactor 1.

[0028] Specifically, a static mixing reactor 1 is used for the continuous addition reaction, which has a lower online liquid hold-up than the traditional batch reactor, resulting in higher reaction efficiency and greater safety and reliability. The continuous reactor has a static mixing structure in its internal channels, which is more conducive to thorough mixing of raw materials, avoids uneven local reactions, effectively suppresses the occurrence of side reactions, and improves product content and yield. The gas-liquid separator 2 is used to separate the by-product carbon dioxide. The tail gas outlet E of the gas-liquid separator 2 is connected to the tail gas treatment system for purifying carbon dioxide, which can be recycled for the preparation of dimethylamine N,N-dimethylcarbamate. The discharge port D of the gas-liquid separator 2 is connected to a centrifuge for outputting a mixture of diuron and solvent, which is then separated in the centrifuge to obtain diuron solid.

[0029] Based on the above-mentioned preparation method of diuron, a continuous feeding method is adopted to realize the continuous addition reaction between raw materials, thereby achieving efficient and continuous production of diuron and improving production efficiency.

[0030] Specifically, it includes the following steps:

[0031] S1. Connect the tail gas outlet E of gas-liquid separator 2 to the tail gas treatment system, open the tail gas valve, and continuously feed the raw material dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate solution into reactor 1 through the feed inlet A of reactor 1. The 3,4-dichlorophenyl isocyanate solution is composed of 3,4-dichlorophenyl isocyanate and a solvent, wherein the solvent is toluene, xylene, chlorobenzene, ethyl acetate, butyl acetate, N-methylpyrrolidone, tetrahydrofuran, etc. One of 2-methyltetrahydrofuran; the mass concentration of 3,4-dichlorophenyl isocyanate in the 3,4-dichlorophenyl isocyanate solution is 5-70%; the molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine N,N-dimethylcarbamate is controlled at 1:0.5-0.55; the jacket temperature of reactor 1 is controlled at -10-70℃, and the reaction temperature is -5-65℃; the two materials undergo an addition reaction in reactor 1 to generate diuron and carbon dioxide as a byproduct.

[0032] As a feasible technical solution, the quantitative addition process can be achieved by controlling the flow rate ratio using a quantitative pump.

[0033] S2. The material obtained from the reaction in step S1 enters the gas-liquid separator 2 for gas-liquid separation to obtain a mixture of diuron and solvent, which is then discharged through outlet D for solid-liquid separation; the by-product carbon dioxide enters the tail gas treatment system for purification through tail gas outlet E.

[0034] S3. The mixture obtained in step S2 is subjected to solid-liquid separation to obtain diuron solid and solvent. The solvent can be recycled, saving solvent consumption and reducing energy waste.

[0035] Specifically, the reaction formula in this embodiment is:

[0036]

[0037] The preparation method and system of this embodiment involve a continuous feedstock delivery system during the addition reaction, allowing the material to be continuously conveyed to the other end, thus achieving a continuous reaction. This system offers advantages such as continuous operation, high efficiency and simplicity, near-zero emissions, and mild reaction conditions. It can effectively shorten reaction time, improve production efficiency, reduce safety risks, and achieve product yields of over 96% and purity of over 98%.

[0038] Example 1

[0039] The tail gas outlet E of reactor 1 is connected to the tail gas treatment system. The tail gas valve is opened, and the jacket temperature of reactor 1 is controlled at -10℃. A solution of dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate is continuously fed into reactor 1 through inlet A. The 3,4-dichlorophenyl isocyanate is a 5% (w / w) toluene solution. The molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine N,N-dimethylcarbamate is controlled at 1:0.5. The reaction temperature is -5℃ to carry out the addition reaction, yielding a mixture of the product diuron and the solvent. After centrifugation, the obtained diuron solid is analyzed by liquid chromatography with external standard method. The product purity is 98.5% and the yield is 96.2%.

[0040] Example 2

[0041] The tail gas outlet E of reactor 1 is connected to the tail gas treatment system. The tail gas valve is opened, and the jacket temperature of reactor 1 is controlled at 0°C. A solution of dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate is continuously fed into reactor 1 through inlet A. The 3,4-dichlorophenyl isocyanate is a 20% (w / w) chlorobenzene solution. The molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine N,N-dimethylcarbamate is controlled at 1:0.55. The reaction temperature is 5°C to carry out the addition reaction, yielding a mixture of the product diuron and the solvent. After centrifugation, the obtained diuron solid is analyzed by liquid chromatography with external standard method. The product purity is 99% and the yield is 97.5%.

[0042] Example 3

[0043] The tail gas outlet E of reactor 1 is connected to the tail gas treatment system. The tail gas valve is opened, and the jacket temperature of reactor 1 is controlled at 30°C. A solution of dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate is continuously fed into reactor 1 through inlet A. The 3,4-dichlorophenyl isocyanate is a 70% N-methylpyrrolidone solution. The molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine N,N-dimethylcarbamate is controlled at 1:0.52. The reaction temperature is 25°C to carry out the addition reaction, yielding a mixture of the product diuron and the solvent. After centrifugation, the obtained diuron solid is analyzed by liquid chromatography with external standard method. The product purity is 99.2% and the yield is 96.6%.

[0044] Example 4

[0045] The tail gas outlet E of reactor 1 is connected to the tail gas treatment system. The tail gas valve is opened, and the jacket temperature of reactor 1 is controlled at 40°C. A solution of dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate is continuously fed into reactor 1 through inlet A. The 3,4-dichlorophenyl isocyanate is a 50% (w / w) 2-methyltetrahydrofuran solution. The molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine N,N-dimethylcarbamate is controlled at 1:0.55. The reaction temperature is 35°C to carry out the addition reaction, yielding a mixture of the product diuron and the solvent. After centrifugation, the obtained diuron solid is analyzed by liquid chromatography with external standard method. The product purity is 98.7% and the yield is 96.8%.

[0046] Example 5

[0047] The tail gas outlet E of reactor 1 is connected to the tail gas treatment system. The tail gas valve is opened, and the jacket temperature of reactor 1 is controlled at 60°C. A solution of dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate is continuously fed into reactor 1 through inlet A. The 3,4-dichlorophenyl isocyanate is a 10% (w / w) ethyl acetate solution. The molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine N,N-dimethylcarbamate is controlled at 1:0.5. The reaction temperature is 55°C to carry out the addition reaction, yielding a mixture of the product diuron and the solvent. After centrifugation, the obtained diuron solid is analyzed by liquid chromatography with external standard method. The product purity is 98.8%, and the yield is 96.7%.

[0048] Example 6

[0049] The tail gas outlet E of reactor 1 is connected to the tail gas treatment system. The tail gas valve is opened, and the jacket temperature of reactor 1 is controlled at 70°C. A solution of dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate is continuously fed into reactor 1 through inlet A. The 3,4-dichlorophenyl isocyanate is a 60% (w / w) butyl acetate solution. The molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine N,N-dimethylcarbamate is controlled at 1:0.53. The reaction temperature is 65°C to carry out the addition reaction, yielding a mixture of the product diuron and the solvent. After centrifugation, the obtained diuron solid is analyzed by liquid chromatography with external standard method. The product purity is 98.9% and the yield is 97.1%.

[0050] Example 7

[0051] The tail gas outlet E of reactor 1 is connected to the tail gas treatment system. The tail gas valve is opened, and the jacket temperature of reactor 1 is controlled at 55°C. A solution of dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate is continuously fed into reactor 1 through inlet A. The 3,4-dichlorophenyl isocyanate is a 5% (w / w) tetrahydrofuran solution. The molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine N,N-dimethylcarbamate is controlled at 1:0.53. The reaction temperature is 50°C to carry out the addition reaction, yielding a mixture of the product diuron and the solvent. After centrifugation, the obtained diuron solid is analyzed by liquid chromatography with external standard method. The product purity is 98.2%, and the yield is 96.9%.

[0052] Example 8

[0053] The tail gas outlet E of reactor 1 is connected to the tail gas treatment system. The tail gas valve is opened, and the jacket temperature of reactor 1 is controlled at 65°C. A solution of dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate is continuously fed into reactor 1 through inlet A. The 3,4-dichlorophenyl isocyanate is a 70% xylene solution. The molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine N,N-dimethylcarbamate is controlled at 1:0.54. The reaction temperature is 60°C to carry out the addition reaction, yielding a mixture of the product diuron and the solvent. After centrifugation, the obtained diuron solid is analyzed by liquid chromatography with external standard method. The product purity is 99.3%, and the yield is 96.5%.

[0054] Example 9

[0055] The tail gas outlet E of reactor 1 is connected to the tail gas treatment system. The tail gas valve is opened, and the jacket temperature of reactor 1 is controlled at 45°C. A solution of dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate is continuously fed into reactor 1 through inlet A. The 3,4-dichlorophenyl isocyanate is a 10% toluene solution. The molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine N,N-dimethylcarbamate is controlled at 1:0.52. The reaction temperature is 40°C to carry out the addition reaction, yielding a mixture of the product diuron and the solvent. After centrifugation, the obtained diuron solid is analyzed by liquid chromatography with external standard method. The product purity is 99.5% and the yield is 97.4%.

[0056] Example 10

[0057] The tail gas outlet E of reactor 1 is connected to the tail gas treatment system. The tail gas valve is opened, and the jacket temperature of reactor 1 is controlled at 50°C. A solution of dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate is continuously fed into reactor 1 through inlet A. The 3,4-dichlorophenyl isocyanate is a 30% N-methylpyrrolidone solution. The molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine N,N-dimethylcarbamate is controlled at 1:0.51. The reaction temperature is 45°C to carry out the addition reaction, yielding a mixture of the product diuron and the solvent. After centrifugation, the obtained diuron solid is analyzed by external standard liquid chromatography, showing a purity of 98.6% and a yield of 98%.

[0058] Example 11

[0059] The tail gas outlet E of reactor 1 is connected to the tail gas treatment system. The tail gas valve is opened, and the jacket temperature of reactor 1 is controlled at 35°C. A solution of dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate is continuously fed into reactor 1 through inlet A. The 3,4-dichlorophenyl isocyanate is a 45% (w / w) chlorobenzene solution. The molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine N,N-dimethylcarbamate is controlled at 1:0.54. The reaction temperature is 30°C to carry out the addition reaction, yielding a mixture of the product diuron and the solvent. After centrifugation, the obtained diuron solid is analyzed by liquid chromatography with external standard method. The product purity is 98.3% and the yield is 97.6%.

[0060] Example 12

[0061] The tail gas outlet E of reactor 1 is connected to the tail gas treatment system. The tail gas valve is opened, and the jacket temperature of reactor 1 is controlled at 5°C. A solution of dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate is continuously fed into reactor 1 through inlet A. The 3,4-dichlorophenyl isocyanate is a 25% (w / w) butyl acetate solution. The molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine N,N-dimethylcarbamate is controlled at 1:0.5. The reaction temperature is 0°C, and an addition reaction is carried out to obtain a mixture of the product diuron and the solvent. After centrifugation, the obtained diuron solid is analyzed by liquid chromatography with external standard method. The product purity is 99.4%, and the yield is 97.2%.

[0062] Comparative Example 1

[0063] Using 3,4-dichlorophenyl isocyanate solution and dimethylamine gas as raw materials, wherein the 3,4-dichlorophenyl isocyanate was a 60% (w / w) butyl acetate solution, the molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine was controlled at 1:1.06, and the reaction temperature was 65℃, an addition reaction was carried out. The conversion rate of the raw material 3,4-dichlorophenyl isocyanate was 95.6% under controlled analysis. The remaining raw material was difficult to convert further. After cooling and filtration, the diuron solid obtained was separated. Liquid chromatography with external standard method analysis showed that the product purity was 96.5% and the yield was 90.3%.

[0064] Comparative Example 2

[0065] Using 3,4-dichlorophenyl isocyanate solution and dimethylamine gas as raw materials, wherein 3,4-dichlorophenyl isocyanate is a 10% (w / w) toluene solution, the molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine is controlled at 1:1.04, and the reaction temperature is 40℃, an addition reaction is carried out. The conversion rate of the raw material 3,4-dichlorophenyl isocyanate is 93.1% under controlled analysis. The remaining raw material is difficult to convert further. After cooling and filtration, the diuron solid obtained is separated. Liquid chromatography with external standard method analysis shows that the product purity is 94.2% and the yield is 88.5%.

[0066] In summary, the product prepared according to the present invention, including diuron and its preparation method and system, has a yield of over 96% and a purity of over 98%, which is far superior to the purity and yield of Comparative Example 1 and Comparative Example 2.

[0067] In the description of this invention, it should be understood that the terms "coaxial," "bottom," "one end," "top," "middle," "other end," "upper," "side," "top," "inner," "front," "center," "both ends," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0068] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0069] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for preparing diuron, characterized in that, Includes the following steps: S1. Under normal temperature and pressure, dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate solution are continuously added to the reactor in a quantitative manner. The dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate solution generate diuron and carbon dioxide as a byproduct in the reactor; the quantitative molar ratio of 3,4-dichlorophenyl isocyanate to dimethylamine N,N-dimethylcarbamate is between 1:0.5 and 1:0.

55. S2. The material obtained from the reaction in step S1 is fed into a gas-liquid separator in a continuous feeding manner to separate the gas and liquid, and obtain a mixture of diuron and solvent. S3. Perform solid-liquid separation on the mixture obtained in step S2 to obtain diuron solid and solvent; In step S1, a continuous static mixing reaction is carried out in a reactor in a solution of dimethylamine N,N-dimethylcarbamate and 3,4-dichlorophenyl isocyanate. The mass concentration of 3,4-dichlorophenyl isocyanate in the 3,4-dichlorophenyl isocyanate solution in step S1 is 5-70%. The reaction temperature inside the reactor in step S1 is -5~65℃; The 3,4-dichlorophenyl isocyanate solution in step S1 is composed of 3,4-dichlorophenyl isocyanate and a solvent, wherein the solvent is one of toluene, xylene, chlorobenzene, ethyl acetate, butyl acetate, N-methylpyrrolidone, tetrahydrofuran, and 2-methyltetrahydrofuran.

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