CN111909066A - Crystallization treatment method for improving quality of mesotrione product - Google Patents

Abstract

The invention provides a crystallization treatment method for improving the quality of mesotrione products, which mainly includes two steps: a seed crystal preparation process and a crystallization process strengthening. Seed preparation process: use dichloroethane solvent system to recrystallize mesotrione solid powder, and obtain mesotrione seed crystals through constant temperature crystallization, filtration and drying; crystallization process enhancement: mesotrione decolorized by activated carbon The organic mother liquor of oxalolone is cooled down to the metastable zone by program, and the prepared sieved crystal seed is added, and mesotrione crystals are obtained after crystal growth, programmed cooling, crystal growth, filtration, rinsing and drying. Through the crystallization method in the present invention, the moisture content of mesotrione is reduced to 3% to 6%, the bulk density of the product reaches 0.75g/cm ³ to 0.85g/cm ³ , and the quantitative content of the product is increased to more than 98.0%, The main particle size can reach 300μm ~ 500μm, with good fluidity.

Description

A kind of crystallization treatment method for improving mesotrione product quality

technical field

The invention belongs to the technical field of pesticide crystallization, in particular to a crystallization treatment method for improving the quality of mesotrione products.

Background technique

Mesotrione, also known as mesotrione, belongs to a broad-spectrum selective herbicide that inhibits hydroxyphenylpyruvate dioxidase (HPPD) in pre-emergence and post-emergence, and can effectively control the main broad-leaved grass and some grass weeds. The molecular formula is C ₁₄ H ₁₃ NO ₇ S, the molecular weight is 339.32, and the chemical name is 2-(4-methanesulfonyl)-2-nitrobenzoyl-cyclohexane-1,3-dione. The chemical structural formula is:

Mesotrione is a triketone herbicide first developed by Syngenta. It was launched in Europe in 2001 under the trade name Callisto. The synthetic reaction of mesotrione is relatively mature, and the synthetic route is as follows: using 4-methylsulfonyl-2-nitrobenzoic acid as raw material, dichloroethane as solvent, acylation with thionyl chloride, and then triethylamine For acid binding agent, it is esterified with cyclohexanedione, and finally uses acetone cyanohydrin as a catalyst to carry out translocation rearrangement to obtain mesotrione:

Three crystal forms of mesotrione have been reported, of which crystal form 1 is a stable crystal form, and crystal forms 2 and 3 are metastable crystal forms. Therefore, crystal form 1 is often used as the production target in industrial production. Stephen Dawson et al. proposed in patent US2008O194880A1 a method for preparing mesotrione crystal form 1 product in an aqueous solution by adjusting the pH value, and a preparation for converting a metastable crystal form 2 product into a stable crystal form 1 product Method; Julie Marie Wichert et al. proposed a method for purifying mesotrione in patent USOO8063253B2, the content includes filtration, adsorption, and organic phase extraction of mesotrione salt aqueous solution to reduce the impurity content in the mesotrione product Arthur Binder et al in patent USOO8063253B2 proposed a method for obtaining pure mesotrione crystal form 1 by adjusting pH value separation and purification in an aqueous solution, and a method by adjusting pH value and adding crystal form 1 seed crystals. Method for converting metastable crystal form 2 to stable crystal form 1; Carmen Cohen et al. disclosed a method from aqueous solution, dimethyl sulfoxide, N,N-dimethylformamide and N-methyl-2 in patent US20120165197A1 -In pyrrolidone and its mixed solution, crystal form 3 of mesotrione is obtained by acidification treatment; James Timothy Bristow et al. proposed a reaction in an organic solvent of petroleum ether, extraction with weak alkaline water, acidification in patent US20160355472A1 Method for preparing mesotrione by water extraction.

The post-processing methods for the transposition rearrangement of mesotrione mainly include the following: in the patents with the patent numbers of CN85109771A and CN1860102A, all adopt the method of adding alkali extraction, acidifying, adding organic solvent to carry out recrystallization, these methods The obtained acidified product has relatively fine particle size and a lot of tar, and the product is easily covered by tar, and when strong alkali is used for the lye, the product is likely to be unstable and tar is generated. Patent Nos. CN18530325A and CN105254543A adopt the method of precipitation to obtain crude product and then recrystallize with alcohol solvent. Recrystallization easily causes product dissolution loss, reduces yield, and additionally introduces a solvent different from the reaction system, which interferes with the process. System environment, in the patent with the patent number of WO2018178860A1, the crude product is dissolved in dichloroethane, and then partially desolvated, extracted to the aqueous phase with potassium bicarbonate, and then acidified to obtain the product. This method first obtains the crude product and then crystallizes itself. The operation is cumbersome, and the product obtained by acidification has a lot of tar, and the product is easily covered by tar. Wang Tao et al. proposed a secondary acidification of the mesotrione reaction solution, separation of the organic phase, and crystallization to obtain the mesotrione product. The innovation of the method lies in the use of secondary acidification technology, which improves the yield, reduces the three wastes, and saves energy and protects the environment.

The evaluation indicators of the product quality of mesotrione mainly include: crystal habit, particle size, moisture content and quantitative content. GB29382-2012 stipulates that the mass fraction (that is, the quantitative content) of mesotrione products is ≥95%, and the requirement for export first-class products is ≥98%. Poor crystal habit and particle size will lead to a large amount of solvent residues. This will seriously affect the determination of mass fraction and reduce product quality. The existing patents mainly propose innovative solutions for separating and converting different crystal forms of mesotrione, improving the purity of reaction products, and optimizing post-processing methods for translocation and rearrangement. Work on good, low-moisture products has not been valued.

Patent CN110078647A acidifies the mesotrione reaction product solution by adding an aqueous solution of hydrochloric acid to separate the organic phase of mesotrione, and then adds potassium bicarbonate aqueous solution to this organic phase for extraction to obtain the aqueous phase of mesotrione, The aqueous solution of hydrochloric acid is then added to this aqueous phase for secondary acidification, and then the organic phase to be crystallized is obtained. The concentration of the filtered organic phase is 0.06g/g solvent to 0.07g/g solvent; in order to improve the yield and reduce losses, add potassium bicarbonate aqueous solution to the filtered organic phase for extraction, and the extracted aqueous phase is mixed with the aqueous phase to be secondary acidified, Simultaneously carry out secondary acidification, stand for stratification, and obtain the final organic phase to be crystallized, and the organic phase at this time is called organic mother liquor. After the organic mother liquor is crystallized, the obtained mesotrione product is mostly powder, as shown in Figure 4, the particle size is small, and it is easy to agglomerate, which in turn causes the product to be difficult to dry, with high moisture content and relatively high dissolved residues. The product parameters are as follows: the moisture content is 13.7%, the bulk density of the product obtained after drying is 0.61 g/cm ³ , the quantitative content is 97.73%, and the Dv(50) is 53 μm. The quantitative content data is lower than 98%, so the product needs to be pulverized and then dried (pulverized into flour) in the subsequent operation. The product parameters after pulverization and drying are: bulk density 0.31g/cm ³ , quantitative content 98.15%. Although powdering and drying can increase the quantitative content of the product, this not only increases the production cost, but also the lower fluidity and bulk density of the powdered product will increase the transportation cost of the product. Therefore, there is an urgent need for a crystallization treatment method, which can not only ensure that the quantitative content of the mesotrione product reaches more than 98%, but also can improve the bulk density and fluidity of the product, so as to reduce the production and transportation costs of mesotrione. The purpose of the present invention is to propose a crystallization method capable of improving the quality of mesotrione products, so as to improve the crystal habit and particle size of the product, reduce the moisture content of the product, effectively shorten the drying time of the product, and improve the quantitative content, fluidity and bulk density of the product, etc. , laying the foundation for the realization of continuous industrial production.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a crystallization treatment method that improves the quality of mesotrione products, improves the crystal habit and particle size of the product, improves the bulk density, fluidity and quantitative content of the product, and reduces the product aggregation caused by too high moisture content. Difficulty in process operations such as knotting, drying, and inconvenient transportation.

On the basis of the organic mother liquor prepared by the method in the patent CN110078647A, the crystallization process of the organic mother liquor is strengthened and controlled. Of course, the organic mother liquor of the present invention is not limited to the organic mother liquor prepared by the method in CN110078647A, and the organic mother liquor of the mesotrione product that needs to provide product quality is suitable for the present invention.

The technical solution adopted by the present invention to solve the technical problem mainly includes two steps. As shown in FIG. 1 , step 1 is the seed crystal preparation process, and step 2 is the crystallization process strengthening stage. The seed crystal preparation process and the crystallization strengthening stage can be carried out in sequence, It can be carried out simultaneously or separately.

The technical scheme of the present invention is as follows:

A crystallization treatment method for improving the quality of mesotrione product, characterized in that it comprises a crystal seed preparation process and a crystallization process strengthening stage:

in:

The preparation process of the seed crystal is as follows: dissolving the powder raw material of mesotrione in a dichloroethane solvent; stirring and dissolving at 50° C. to 55° C.; crystals, and then filtered and dried to obtain mesotrione seed crystals, as shown in Figures 2a, 2b, and 2c, which are seeds with different particle sizes;

In the process of preparing the crystal seed, the powder raw material of mesotrione is dissolved in the dichloroethane solvent in a mass ratio of 0.14-0.16:1.

During the preparation process of the seed crystal, the mixture is stirred and dissolved at 50° C. to 55° C., and the stirring rate is 200 rpm to 250 rpm.

In the process of preparing the seed crystal, the crystal growing time is 3-5h.

The strengthening stage of the crystallization process includes the following steps:

1) adding 1%～1.5% of acidic activated carbon powder based on the mass of the organic mother liquor to decolorize the organic mother liquor by stirring at 50°C～55°C;

2) After the decolorization finishes, the organic mother liquor is filtered by heat, and the temperature is programmed to be cooled to 40°C to 45°C within 20 to 60 minutes;

3) adding 3% to 5% of the mass of the organic mother liquor as seed crystals;

4) Under the constant temperature condition of 40℃～45℃, the crystal growth time is 30～180min;

5) After the crystal growth is completed, the temperature is lowered to 10°C to 15°C in 60 to 180 minutes, and the primary crystal product is separated out in the crystallization kettle;

6) Continue to keep the obtained primary crystal product in suspension in the crystallization kettle, keep the end temperature constant at 10°C to 15°C, and keep the crystal at a constant temperature for 30 to 300 minutes;

7) After the crystal growth is completed, the mesotrione product is obtained by filtering, rinsing and drying.

In step 1) of the strengthening stage of the crystallization process, decolorization is performed by stirring, and the decolorization time is 20-60 min, and the stirring rate is 200 rpm-250 rpm.

In the step 2) of the strengthening stage of the crystallization process, the temperature is reduced by a program, and the cooling rate is 10-45° C./h.

In step 3) of the strengthening stage of the crystallization process, a seed crystal is added, and the particle size of the seed crystal is in the range of 150-450 μm.

In the step 5) of the strengthening stage of the crystallization process, the temperature is reduced by a program, and the cooling rate is 8-35° C./h.

The product in step 7) of the strengthening stage of the crystallization process is rinsed with dichloroethane at 0-10°C.

The patents about mesotrione products that have been reported are all from the perspective of removing impurities and controlling reaction conditions to improve the purity of mesotrione products, but as an important parameter for evaluating the quality of mesotrione products: crystal habit and particle size , but did not attract enough attention. The product obtained by the method in the patent CN110078647A is an example, because no attention is paid to the crystallization process and control of the organic mother liquor, the product is mostly slag, as shown in Figure 4, the particle size is small, it is easy to coalesce, and there is no crystal luster, which in turn leads to In the subsequent drying process, it is difficult to reduce the dissolved residue, and it is possible to reduce the dissolved residue by powdering and re-evaporation. However, there is a certain difficulty in the transfer process of flour, which increases the production cost and transportation cost.

The beneficial effects of the present invention are as follows: the single crystal of mesotrione crystal is obtained by slow evaporation in different organic solvents, and the data of the mesotrione single crystal is analyzed and simulated by the Materials Studio software, as shown in Figure 7b It is found that the crystal habit of mesotrione under vacuum is a symmetrical polyhedral structure. If it can be successfully prepared, it will be of great significance for actual production and transportation; as shown in Figure 7a, it is the scanning electron microscope image of the actual product. This method is based on the simulation and prediction of the crystal habit of MaterialsStudio. The first batch of seeds with better crystal quality are obtained through recrystallization process optimization, seed optimization and sieving, and an appropriate amount of seeds is added during the nucleation induction period of the organic mother liquor. The stable 1-crystal product obtained by this cooling and crystallization method not only has better crystal habit and larger particle size, but also reduces the moisture content and quantitative content of the product, thereby improving the bulk density and fluidity of the product, effectively reducing the Cost of production and transportation of mesotrione products. Through the crystallization method in the present invention, the moisture content of mesotrione is reduced to 3% to 6%, the bulk density of the product reaches 0.75g/cm ³ to 0.85g/cm ³ , and the quantitative content of the product is increased to more than 98.0%, The main particle size can reach 300μm ~ 500μm, with good fluidity.

Description of drawings

Fig. 1 is the process flow schematic diagram of the present invention;

Figure 2a is a SEM image of the seed crystal obtained in Example 1 with a particle size of 150 μm to 200 μm after sieving;

Figure 2b is a SEM image of the seed crystal obtained in Example 1 with a particle size of 200 μm to 300 μm after sieving;

Figure 2c is a SEM image of the seed crystal obtained in Example 1 with a particle size of 300 μm to 450 μm after sieving;

Fig. 3 is the SEM image of the product obtained in Example 1;

Fig. 4 is the SEM image of the product obtained in Example 7;

Fig. 5 is the XRD powder diffractogram obtained in Example 1;

Fig. 6 is the particle size distribution diagram that embodiment 1 obtains;

Fig. 7a embodiment 1 gained single product SEM photo;

Figure 7b shows the vacuum simulated crystal habit.

Specific implementation method

The above-mentioned content of the present invention will be further described in detail with the specific implementation in the form of examples below. However, it should not be understood that the scope of the above-mentioned subject matter of the present invention is limited to the following examples. All technologies implemented based on the above content of the present invention belong to the scope of the present invention.

Example 1

Step 1, the seed crystal preparation process:

1) get powder raw material product 16g, add in the crystallizer of 250mL filled with 100g dichloroethane solvent;

2) be warming up to 55 ℃ of dissolving clear, stirring speed is 250rpm;

3) Cool down to 15°C at a constant speed within 120min;

4) Cultivate crystals at a constant temperature for 5h at 15°C, filter and dry to obtain 9.8g of seed crystals;

Step 2, strengthen the crystallization process:

1) get 340gm organic mother liquor (mass concentration is about 0.16), add 5.1g acidic activated carbon powder, in 55 ℃ of oil bath pot, under 250rpm stirring speed, stir 60min;

2) Use a preheated round-bottomed flask and a funnel to filter the decolorizing mother liquor, quickly place the filtered mother liquor in a crystallizer whose temperature is controlled by an ice machine at 55°C, and program the temperature to 45°C in 60min;

3) Add 3.0 g of prepared seed crystals;

4) Cultivate crystals for 180min at 45℃;

5) After the crystal growth is completed at 45°C, program cooling to 10°C within 180min;

6) Cultivate crystals at 10°C for 300min to consume the remaining supersaturation;

7) After culturing at 10°C, filter part of the slurry, rinse with glacial dichloroethane (0°C) for 2 to 3 times, filter with suction until no droplets fall, and transfer the wet product to a watch glass. The weight is 22.00g, and the weight after drying is 20.70g.

The quality of the obtained product was characterized: the moisture content was 3.1%; as shown in Figure 5, a solid product of stable crystal form (1 crystal form) was obtained after drying; as shown in Figure 6, the product Dv(50) was 499 μm; as shown in Figure 3 As shown, the particle size of the product is large and uniform, the bulk density is 0.81 g/cm ³ , and the quantitative content is 98.35%. Using the crystallization method in the patent CN110078647A, the moisture content of mesotrione is 13.7%, and after drying, the bulk density of the product is 0.61g/cm ³ , the quantitative content is 97.73%, and the Dv(50) is 53 μm. Mesotrione prepared by this method The quality of ketone products has been significantly improved.

Example 2

Step 1, the seed crystal preparation process:

1) get 14g of original powder product, add in the crystallizer of 250mL filled with 100g of dichloroethane solvent;

2) be warming up to 50 ℃ of dissolving clear, stirring speed is 200rpm;

3) Cool down to 10°C at a constant speed within 240min;

4) Cultivate crystals at a constant temperature for 3h at 10°C, filter and dry to obtain 8.7g of seed crystals;

Step 2, strengthen the crystallization process:

1) Take 329 gm of organic mother liquor (mass concentration is about 0.17), add 3.3 g of acidic activated carbon powder, and stir for 20 min in a 50° C. oil bath at a stirring speed of 200 rpm;

2) Use a preheated round-bottomed flask and a funnel to filter the decolorizing mother liquor, quickly place the filtered mother liquor in a crystallizer whose temperature is controlled by an ice machine at 50°C, and program the temperature to 40°C in 20min;

3) Add 1.7 g of prepared seed crystals;

4) Cultivate crystals at 40°C for 30min;

5) After culturing at 40°C, program cooling to 10°C within 60 minutes;

6) Cultivate crystals at 10°C for 30min to consume the remaining supersaturation;

7) After culturing at 10°C, filter part of the slurry, rinse with glacial dichloroethane (10°C) for 2 to 3 times, filter with suction until no droplets fall, and transfer the wet product to a watch glass. The weight is 17.40g, and the weight after drying is 16.68g.

The quality of the obtained product is characterized: the moisture content is 3.1%, the product is obtained after drying, the bulk density is 0.78g/cm ³ , the quantitative content before powdering is 98.20%, and the Dv(50) is 324 μm; Nitrosulfur is obtained by the crystallization method in the patent CN110078647A The moisture content of oxalolone is 13.7%. After drying, the bulk density of the product is 0.61 g/cm ³ , the quantitative content is 97.73%, and the Dv(50) is 53 μm. The quality of the mesotrione prepared by this method is obviously improved.

Example 3

Step 1, the seed crystal preparation process:

1) get 15g of original powder product, add in the crystallizer of 250mL filled with 100g of dichloroethane solvent;

2) be warming up to 53 ℃ of dissolving clear, stirring speed is 230rpm;

3) Cool down to 13°C at a constant speed within 120min;

4) Cultivate crystals at a constant temperature for 4 hours at 13°C, filter and dry to obtain 9.1g of seed crystals;

Step 2, strengthen the crystallization process:

1) get 247.4gm organic mother liquor (mass concentration is about 0.17), add 3.7g acid activated carbon powder, in 53 ℃ of oil bath pot, under 230rpm stirring speed, stir 40min;

2) Use a preheated round-bottomed flask and a funnel to filter the decolorizing mother liquor, quickly place the filtered mother liquor in a crystallizer whose temperature is controlled by an ice machine at 53°C, and program the temperature to 43°C in 40min;

3) Add 1.5 g of prepared seed crystals;

4) Cultivate crystals at 43°C for 100min;

5) After the crystal growth is completed at 43°C, the temperature is reduced to 13°C within 120min;

6) Cultivate crystals for 130min at 13°C to consume the remaining supersaturation;

7) After culturing at 13°C, filter the slurry, rinse with glacial dichloroethane (8°C) for 2 to 3 times, filter with suction until no droplets fall, and transfer the wet product to a watch glass. was 32.8g, and weighed 30.9g after drying.

Characterize the quality of the obtained product: the moisture content is 5.8%, the product is obtained after drying, the bulk density is 0.85g/cm ³ , the quantitative content before powdering is 98.11%, and the Dv(50) is 407 μm; Nitrosulfur is obtained by the crystallization method in the patent CN110078647A The moisture content of oxalolone is 13.7%. After drying, the bulk density of the product is 0.61 g/cm ³ , the quantitative content is 97.73%, and the Dv(50) is 53 μm. The quality of the mesotrione prepared by this method is obviously improved.

Example 4

Step 1, the seed crystal preparation process:

1) get 15g of original powder product, add in the crystallizer of 250mL filled with 100g of dichloroethane solvent;

2) be warming up to 52 ℃ of dissolving clear, stirring speed is 210rpm;

3) Cool down to 10°C at a constant speed within 200min;

4) Cultivate crystals at a constant temperature for 3h at 10°C, filter and dry to obtain 9.6g of seed crystals;

Step 2, strengthen the crystallization process:

1) Take 353gm of organic mother liquor (mass concentration is about 0.18), add 3.5g of acidic activated carbon powder, and stir for 40min in a 52°C oil bath at a stirring speed of 220rpm;

2) Use a preheated round-bottom flask and a funnel to filter the decolorizing mother liquor, quickly place the filtered mother liquor in a crystallizer whose temperature is controlled by an ice machine at 52°C, and program the temperature to 43°C in 30min;

3) Add 3.4 g of prepared seed crystals;

4) Cultivate crystals for 110min at 43℃;

5) After the crystal growth is completed at 43°C, the temperature is reduced to 13°C within 120min;

6) Cultivate crystals for 200min at 13°C to consume the remaining supersaturation;

7) After culturing at 13°C, filter part of the slurry, rinse with glacial dichloroethane (3°C) for 2 to 3 times, filter with suction until no droplets fall, and transfer the wet product to a watch glass. The weight was 25.1g, and the weight after drying was 23.9g.

Characterize the quality of the obtained product: the moisture content is 4.6%, the product is obtained after drying, the bulk density is 0.83g/cm ³ , the quantitative content before powdering is 98.50%, and the Dv(50) is 426 μm; Nitrosulfur is obtained by the crystallization method in the patent CN110078647A The moisture content of oxalolone is 13.7%. After drying, the bulk density of the product is 0.61 g/cm ³ , the quantitative content is 97.73%, and the Dv(50) is 53 μm. The quality of the mesotrione prepared by this method is obviously improved.

Example 5

Step 1, the seed crystal preparation process:

1) get 16g of original powder product, add in the crystallizer of 250mL filled with 100g of dichloroethane solvent;

2) be warming up to 54 ℃ of dissolving clear, stirring speed is 240rpm;

3) Cool down to 10°C at a constant speed within 150min;

4) Cultivate the crystals at a constant temperature for 4h at 10°C, filter and dry to obtain 10.3g of seed crystals;

Step 2, strengthen the crystallization process:

1) Take 262gm of organic mother liquor (mass concentration is about 0.18), add 2.6g of acidic activated carbon powder, and stir for 30min in a 53°C oil bath at a stirring speed of 230rpm;

2) Use a preheated round-bottomed flask and a funnel to filter the decolorizing mother liquor, quickly place the filtered mother liquor in a crystallizer whose temperature is controlled by an ice machine at 53°C, and program the temperature to 42°C in 42min;

3) Add 2.1 g of prepared seed crystals;

4) Cultivate crystals for 150min at 42℃;

5) After the crystal growth is completed at 42°C, the temperature is lowered to 10°C within 120min;

6) Cultivate crystals at 10°C for 100min to consume the remaining supersaturation;

7) After culturing at 10°C, filter part of the slurry, rinse with glacial dichloroethane (6°C) for 2 to 3 times, filter with suction until no droplets fall, and transfer the wet product to a watch glass. The weight is 31.5g, and the weight after drying is 30.3g.

The quality of the obtained product is characterized: the moisture content is 3.8%, the product is obtained after drying, the bulk density is 0.84g/cm ³ , the quantitative content before powdering is 98.50%, and the Dv(50) is 389 μm; Nitrosulfur is obtained by the crystallization method in the patent CN110078647A The moisture content of oxalolone is 13.7%. After drying, the bulk density of the product is 0.61 g/cm ³ , the quantitative content is 97.73%, and the Dv(50) is 53 μm. The quality of the mesotrione prepared by this method is obviously improved.

Example 6

Step 1, seed crystal preparation stage:

1) get 15g of original powder product, add in the crystallizer of 250mL filled with 100g of dichloroethane solvent;

2) be warming up to 53 ℃ of dissolving clear, stirring speed is 240rpm;

3) Cool down to 10°C at a constant speed within 150min;

4) Cultivate crystals at a constant temperature for 300min at 10°C, filter and dry to obtain 10.7g of seed crystals;

Step 2, strengthen the crystallization process:

1) Take 305g of organic mother liquor (mass concentration is about 0.16), add 4g of acidic activated carbon powder, and stir for 30min in a 53°C oil bath at a stirring speed of 220rpm;

2) Use a preheated round-bottomed flask and a funnel to filter the decolorizing mother liquor, quickly place the filtered mother liquor in a crystallizer whose temperature is controlled by an ice machine at 53°C, and program the temperature to 43°C in 50min;

3) Add 2.5g of prepared seed crystals;

4) Cultivate crystals for 60min at 43℃;

5) After the crystal growth is completed at 43°C, the temperature is lowered to 10°C within 120min;

6) Cultivate crystals at 10°C for 120min to consume the remaining supersaturation;

7) After culturing at 10°C, filter part of the slurry, rinse with glacial dichloroethane (2°C) for 2 to 3 times, filter with suction until no droplets fall, and transfer the wet product to a watch glass. The weight was 20.8g, and the weight after drying was 19.7g.

Characterize the quality of the obtained product: the moisture content is 5.2%, the product is obtained after drying, the bulk density is 0.75g/cm ³ , the quantitative content before powdering is 98.06%, and the Dv(50) is 392 μm; Nitrosulfur is obtained by the crystallization method in the patent CN110078647A The moisture content of oxalolone is 13.7%. After drying, the bulk density of the product is 0.61 g/cm ³ , the quantitative content is 97.73%, and the Dv(50) is 53 μm. The quality of the mesotrione prepared by this method is obviously improved.

The technical solutions disclosed and proposed in the present invention can be realized by those skilled in the art by referring to the content of this article and appropriately changing the conditions, routes and other links. The methods and technical routes described herein can be modified or recombined without departing from the content, spirit and scope of the present invention to achieve the final preparation technology. It should be particularly pointed out that all similar substitutions and modifications apparent to those skilled in the art are deemed to be included in the spirit, scope and content of the present invention.

Claims (9)

1. A crystallization treatment method for improving the quality of mesotrione products is characterized by comprising a crystal seed preparation process and a crystallization process strengthening stage;

the preparation process of the seed crystal comprises the following steps: dissolving a mesotrione powder raw material in a dichloroethane solvent; stirring and dissolving at 50-55 ℃; then cooling to 10-15 ℃ within 120-240 min by adopting a cooling crystallization method, growing crystals, filtering and drying to obtain mesotrione seed crystals;

the strengthening stage of the crystallization process comprises the following steps:

1) adding acidic activated carbon powder accounting for 1-1.5% of the mass of the organic mother liquor to stir and decolor the organic mother liquor at 50-55 ℃;

2) after the decolorization is finished, carrying out hot filtration on the organic mother liquor, and carrying out programmed cooling to 40-45 ℃ within 20-60 min;

3) adding screened seed crystal with the mass of 3-5% of the organic mother liquor;

4) growing the crystal for 30-180 min at 40-45 ℃;

5) after the crystallization is finished, the temperature is reduced to 10-15 ℃ within 60-180 min, and a primary crystal product is separated out from the crystallization kettle;

6) continuously keeping the obtained primary crystal product in a crystallization kettle for suspension, keeping the end temperature to be 10-15 ℃ unchanged, and growing crystals at constant temperature for a period of time, wherein the crystal growing time is 30-300 min;

7) and after the crystal growth is finished, filtering, leaching and drying to obtain a mesotrione product.

2. The method as set forth in claim 1, characterized in that the mesotrione powder raw material is dissolved in dichloroethane solvent in a mass ratio of 0.14-0.16: 1 during the seed crystal preparation process.

3. The method as set forth in claim 1, wherein the seed crystal is dissolved by stirring at a temperature of 50 ℃ to 55 ℃ at a stirring speed of 200rpm to 250 rpm.

4. The method of claim 1, wherein the time for growing the seed crystal in the process of preparing the seed crystal is 3-5 hours.

5. The method as set forth in claim 1, wherein the decoloring is performed by stirring in the step 1) of the strengthening stage of the crystallization process, the decoloring time is 20 to 60min, and the stirring speed is 200 to 250 rpm.

6. The method as set forth in claim 1, wherein the temperature of the crystallization process is reduced at a rate of 10 to 45 ℃/h in the strengthening stage step 2).

7. The method as set forth in claim 1, wherein the seed crystal is added in the step 3) of the strengthening stage of the crystallization process, and the particle size of the seed crystal is in the range of 150 to 450 μm.

8. The method as set forth in claim 1, wherein the temperature of the crystallization process is reduced at a rate of 8 to 35 ℃/hr in the strengthening stage of crystallization step 5).

9. The method as set forth in claim 1, wherein the product is rinsed in the strengthening stage of crystallization step 7) using dichloroethane of 0 to 10 ℃.

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