Production process of diuron active compound

Abstract

The invention specifically discloses a diuron technical production process, which comprises: S1, placing 3, 4-dichloroaniline and toluene in a dehydration kettle, and carrying out heating dehydration for standby application; s2, toluene is placed in a cold light kettle and cooled, a 3, 4-dichloroaniline toluene solution is dropwise added while phosgene is introduced for a reaction, and 3, 4-dichlorophenyl isocyanate is obtained; s3, heating to a reaction temperature, adding a porous carbon supported selenium catalyst, introducing dimethylamine gas, and carrying out a heat preservation reaction after the introduction is finished; and after the reaction is finished, purifying to obtain the diuron active compound. On one hand, dimethylamine gas is directly introduced into an organic phase for reaction, so that 3, 4-dichlorophenyl isocyanate is prevented from being decomposed in a water phase, and the yield and purity of the product are improved; and on the other hand, the porous carbon material can accelerate transmission of a substrate in the catalyst, minimize mass transfer resistance, shorten a mass transfer path and further improve catalytic activity, and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a production process of diuron technical. Background Art

[0002] The chemical name of diuron is 3-(3,4-dichlorophenyl)-1,1-dimethylurea. It is a phenyl-substituted urea herbicide with systemic conduction and certain contact effects. It is effective against most annual and perennial weeds. It is mainly used in crops such as cotton, soybeans, tomatoes, tobacco, grapes, orchards, and rubber plantations to control annual grass weeds and certain broad-leaved weeds, such as barnyardgrass, crabgrass, foxtail grass, wild amaranth, and sedge.

[0003] At present, the traditional industrial preparation method of diuron technical is the phosgene method. This method usually uses p-chloronitrobenzene as the starting material, firstly obtains 3,4-dichloronitrobenzene through chlorination reaction, then obtains 3,4-dichloroaniline through reduction reaction, and then reacts with phosgene to generate 3,4-dichlorophenyl isocyanate, which is then added with dimethylamine aqueous solution to obtain the target product diuron technical. This method involves multiple steps of reaction and a long synthesis route, resulting in cumbersome operation, low production efficiency and high cost; isocyanate is easily hydrolyzed in dimethylamine aqueous solution, resulting in reduced yield and purity of the target product.

[0004] In view of the important application of diuron technical in agriculture and the many defects in its preparation method, it is particularly important and urgent to actively develop a new method for synthesizing diuron technical that is environmentally friendly, simple in route, easy to operate, and economical and efficient. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a production process of diuron technical. The diuron technical is prepared by the method provided by the present invention, and the route is short and environmentally friendly.

[0006] The technical solution of the present invention is achieved in this way:

[0007] A production process of diuron technical comprises the following steps:

[0008] S1: Place 1 mol of 3,4-dichloroaniline and 5 mol of toluene in a dehydration kettle, heat to 105°C and dehydrate for 2 hours before use;

[0009] S2: Place 5 mol of toluene in a cold light reactor and cool it to 10°C. Add 2 mol of phosgene at a constant rate of 0.5 h and add 2 kg·h -1 3,4-dichloroaniline toluene solution is added dropwise at a rate of 100 to react to obtain 3,4-dichlorophenyl isocyanate;

[0010] S3: After heating to the reaction temperature, add porous carbon-supported selenium catalyst and introduce dimethylamine gas, and after the ventilation is completed, carry out heat preservation reaction; after the reaction is completed, purify to obtain the diuron technical.

[0011] This process directly introduces dimethylamine gas into the organic phase for reaction, avoiding the decomposition of 3,4-dichlorophenyl isocyanate in the aqueous phase, improving the yield and purity of the product, saving costs, and generating no wastewater, which is beneficial to environmental protection. The obtained product is easy to dry, the post-processing process is simple, and equipment and investment are reduced.

[0012] Furthermore, in step S3, the amount of the porous carbon-supported selenium catalyst is 1%-5% of the mass of 3,4-dichloroaniline.

[0013] Porous carbon materials have two or more types of interconnected pores, and possess the combined advantages of multiple single-stage pores. They can accelerate the transfer of substrates in the catalyst, minimize mass transfer resistance, shorten the mass transfer path, and further improve catalytic activity.

[0014] Furthermore, the amount of dimethylamine used in step S3 is 1.0-1.2 of the amount of 3,4-dichloroaniline substance.

[0015] A slight excess of dimethylamine is beneficial to the reaction, but too much excess will increase the cost. Dimethylamine is a strong base, and the product diuron technical is easily soluble in toluene under strong alkaline conditions, so dimethylamine should not be used in too much excess.

[0016] Furthermore, in step S3, the reaction temperature is 65-75° C., and the insulation time is 1.5-2.5 h.

[0017] If the temperature is too low, the reaction will not be complete, affecting the yield; if the temperature is too high, more dimethylamine gas will escape, also affecting the yield.

[0018] If the time is too short, the reaction will not be sufficient; if the time is too long, it will consume energy and increase costs.

[0019] Furthermore, the preparation method of the porous carbon-supported selenium catalyst is:

[0020] S1: Mix and grind cellulose and sodium bicarbonate, and calcine at elevated temperature under the protection of inert gas;

[0021] S2: After cooling to room temperature, washing with deionized water until neutral, filtering and drying the filter cake to obtain a porous carbon material;

[0022] S3: placing the porous carbon material in deionized water, adding selenium nitrate, and heating and stirring until dry;

[0023] S4: After drying, calcining is performed under the protection of an inert gas to obtain the porous carbon-supported selenium catalyst.

[0024] Furthermore, the calcination conditions in step S1 are: 750-850° C., 1-1.5 h.

[0025] Furthermore, the drying conditions in step S2 are: 75-85° C., 10-15 h.

[0026] Furthermore, the amount of selenium nitrate used in step S3 is 5-20% of the mass of the porous carbon material.

[0027] Furthermore, the calcination conditions in step S4 are: 350-450° C., 1.5-2.5 h.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. Directly introducing dimethylamine gas into the organic phase for reaction avoids the decomposition of 3,4-dichlorophenyl isocyanate in the aqueous phase and improves the yield and purity of the product.

[0030] 2. Porous carbon materials can accelerate the transfer of substrates in the catalyst, minimize mass transfer resistance, shorten the mass transfer path, and further improve catalytic activity. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Reagent Description

[0033] 3,4-Dichloroaniline, toluene, phosgene, methyl cellulose, sodium bicarbonate, selenium nitrate, analytical grade, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0034] Preparation Example 1:

[0035] Preparation of porous carbon supported selenium catalyst:

[0036] S1: 10 g of methyl cellulose and 30 g of sodium bicarbonate were mixed and ground thoroughly, and heated at 10 °C min under nitrogen atmosphere. -1 The temperature was raised to 800°C and calcined for 1h;

[0037] S2: After cooling to room temperature, washing in deionized water until neutral, filtering and drying at 80°C for 12 h to obtain a porous carbon material;

[0038] S3: Weigh 10 g of porous carbon material and dissolve it in 100 mL of deionized water, add 1 g of selenium nitrate and heat at 80 °C with stirring until dry;

[0039] S4: After drying, transfer to a tube furnace and heat at 510℃·min under nitrogen protection. -1 The temperature is raised to 400° C. at a rate of 100° C. and maintained for 2 h to obtain the porous carbon-supported selenium catalyst.

[0040] Example 1

[0041] S1: Place 162 g of 3,4-dichloroaniline and 460 g of toluene in a dehydration kettle, heat to 105°C and dehydrate for 2 hours before use;

[0042] S2: Place 460 g of toluene in a cold light reactor and cool to 10 °C. Add 2 mol of phosgene at a constant rate of 0.5 h and add 2 kg·h -1 3,4-dichloroaniline toluene solution is added dropwise at a rate of 100 to react to obtain 3,4-dichlorophenyl isocyanate;

[0043] S3: Raise the temperature to 70°C, add 5g of the porous carbon-supported selenium catalyst described in Preparation Example 1, and introduce 1.1mol of dimethylamine gas, and keep the temperature at 70°C for 2h. After the reaction is completed, filter and dry the filter cake at 90°C for 3h to obtain the diuron technical.

[0044] Example 2

[0045] The difference between this embodiment and embodiment 1 is that the reaction temperature in step S3 is 65°C.

[0046] The other parts are exactly the same as those in Example 1.

[0047] Example 3

[0048] The difference between this embodiment and embodiment 1 is that the reaction temperature in step S3 is 75°C.

[0049] The other parts are exactly the same as those in Example 1.

[0050] Example 4

[0051] The difference between this embodiment and embodiment 1 is that the reaction time in step S3 is 1.5 h.

[0052] The other parts are exactly the same as those in Example 1.

[0053] Example 5

[0054] The difference between this embodiment and embodiment 1 is that the reaction time in step S3 is 2.5 h.

[0055] The other parts are exactly the same as those in Example 1.

[0056] Example 6

[0057] The difference between this embodiment and embodiment 1 is that the amount of the porous carbon-supported selenium catalyst used in step S3 is 1.62 g.

[0058] The other parts are exactly the same as those in Example 1.

[0059] Example 7

[0060] The difference between this embodiment and embodiment 1 is that the amount of the porous carbon-supported selenium catalyst used in step S3 is 8.1 g.

[0061] The other parts are exactly the same as those in Example 1.

[0062] Example 8

[0063] The difference between this embodiment and embodiment 1 is that the amount of dimethylamine used in step S3 is 1 mol.

[0064] The other parts are exactly the same as those in Example 1.

[0065] Example 9

[0066] The difference between this embodiment and embodiment 1 is that the amount of dimethylamine used in step S3 is 1.2 mol.

[0067] The other parts are exactly the same as those in Example 1.

[0068] Example 10

[0069] The difference between this embodiment and embodiment 1 is that the amount of selenium nitrate used in step S3 of preparation example 1 is 0.5 g.

[0070] The other parts are exactly the same as those in Example 1.

[0071] Embodiment 11

[0072] The difference between this embodiment and embodiment 1 is that the amount of selenium nitrate used in step S3 of preparation example 1 is 2 g.

[0073] The other parts are exactly the same as those in Example 1.

[0074] Comparative Example 1

[0075] The difference between this comparative example and Example 1 is that the porous carbon-supported selenium catalyst in step S3 is replaced with selenium nitrate.

[0076] The other parts are exactly the same as those in Example 1.

[0077] Comparative Example 2

[0078] The difference between this comparative example and Example 1 is that the amount of the porous carbon-supported selenium catalyst used in step S3 is 0 g.

[0079] The other parts are exactly the same as those in Example 1.

[0080] Tests and Results

[0081] The yield and purity of diuron technical are shown in Table 1.

[0082] Table 1

[0083]

[0084]

[0085] It can be seen from Examples 1-3 that when the temperature is 65°C, the reaction is not fully carried out, affecting the product yield. When the temperature is 75°C, more xylene gas will escape, and the yield will decrease.

[0086] It can be seen from Examples 1 and 4-5 that when the reaction time is 1.5 h, the reaction is not fully carried out and the yield is low. A higher yield is achieved when the reaction time is 2 h. When the reaction time is extended to 2.5 h, the yield does not increase significantly, but the purity is reduced.

[0087] It can be seen from Example 1, Examples 6-7 and Comparative Example 2 that the amount of porous carbon-supported selenium catalyst used has a significant effect on the product yield.

[0088] It can be seen from Examples 1 and 8-9 that when the amount of dimethylamine is increased from 1 mol to 1.1 mol, a slight excess is beneficial to the reaction and improves the reaction yield, but further increasing the amount of dimethylamine will not increase the reaction yield.

[0089] It can be seen from Example 1, Examples 10-11 and Comparative Example 1 that loading selenium nitrate on a porous carbon material with a microporous structure can make the selenium nitrate better dispersed, better contact with the reaction substrate, promote the full reaction, and improve the product yield and purity.

[0090] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A production process of diuron technical, characterized in that: The steps include: S1: Place 3,4-dichloroaniline and toluene in a dehydration kettle, heat up and dehydrate them for later use; S2: placing toluene in a cold light reactor and cooling it, while passing phosgene, adding 3,4-dichloroaniline toluene solution dropwise to react, thereby obtaining 3,4-dichlorophenyl isocyanate; S3: After heating to the reaction temperature, add porous carbon-supported selenium catalyst and introduce dimethylamine gas, and after the ventilation is completed, carry out heat preservation reaction; after the reaction is completed, purify to obtain the diuron technical.

2. The production process of diuron technical according to claim 1, characterized in that: In step S1, the molar ratio of 3,4-dichloroaniline to toluene is 1:5, and the dehydration conditions are 105° C. for 2 h.

3. The production process of diuron technical according to claim 1, characterized in that: In step S2, the cooling temperature is 10°C, the molar ratio of phosgene to 3,4-dichloroaniline is 2:1, and the phosgene introduction rate is 4 mol·h -1 , the dropping speed of 3,4-dichloroaniline toluene solution is 2kg·h -1 .

4. The production process of diuron technical according to claim 1, characterized in that: In step S3, the reaction temperature is 65-75° C., and the insulation time is 1.5-2.5 h; the amount of the porous carbon-supported selenium catalyst is 1%-5% of the mass of 3,4-dichloroaniline; and the amount of dimethylamine is 1.0-1.2 of the amount of 3,4-dichloroaniline.

5. The production process of diuron technical according to claim 1, characterized in that: The preparation method of the porous carbon-supported selenium catalyst is: S1: Mix and grind cellulose and sodium bicarbonate, and calcine at elevated temperature under the protection of inert gas; S2: After cooling to room temperature, washing with deionized water until neutral, filtering and drying the filter cake to obtain a porous carbon material; S3: placing the porous carbon material in deionized water, adding selenium nitrate, and heating and stirring until dry; S4: After drying, calcining is performed under the protection of an inert gas to obtain the porous carbon-supported selenium catalyst.

6. The production process of diuron technical according to claim 5, characterized in that: The calcination conditions in step S1 are: 750-850° C., 1-1.5 h.

7. The production process of diuron technical according to claim 5, characterized in that: The drying conditions in step S2 are: 75-85° C., 10-15 h.

8. The production process of diuron technical according to claim 5, characterized in that: The amount of selenium nitrate used in step S3 is 5-20% of the mass of the porous carbon material.

9. The production process of diuron technical according to claim 5, characterized in that: The calcination conditions in step S4 are: 350-450° C., 1.5-2.5 h.

10. The production process of diuron technical according to claim 5, characterized in that: In step S1, the mass ratio of cellulose to sodium bicarbonate is 1:3.

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