Crystallization method of benzotriazoles and use thereof

Abstract

The application discloses a crystallization method and device of a benzotriazole compound. The crystallization method comprises mixing a reaction liquid containing the benzotriazole compound and a crystallization solvent in a jet mixer, and then crystallizing the mixed stream in a crystallization kettle. The method has higher product yield, significantly reduces the temperature of the mixed reaction liquid and crystallization solvent, shortens the crystallization time, has a short process flow, and can directly obtain a qualified benzotriazole product with a narrower particle size distribution, a larger specific surface area, higher purity and lower solvent residue.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fine chemical products, and particularly relates to a crystallization method of a benzotriazole compound and application thereof. BACKGROUND

[0002] The ultraviolet absorber UV-360 (2,2'-methylene-bis(4-t-octyl-6-benzotriazolyl) phenol) is a light stabilizer which does not discolor, does not pollute, is resistant to water extraction, does not volatilize at processing temperature, and has light and thermal stability. Its structural formula is as follows:

[0003]

[0004] UV-360 is widely used in polypropylene (PP), polyethylene (PE); it is also suitable for polystyrene, ABS resin, polyvinyl chloride (PVC), nylon, polyurethane, etc. When used with light stabilizers, it has a synergistic effect. UV-360 is insoluble in water, soluble in ester and benzene solvents, and has high thermal stability. In the cosmetics industry, UV-360 can provide the most extensive ultraviolet protection as a broad-spectrum sunscreen. Because cosmetics are in direct contact with the human body, higher quality is required for the product: higher purity, smaller particle size, and stricter requirements for solvent residues.

[0005] Regarding the preparation of UV360, the prior art mainly focuses on the synthesis method of the substance, and there is little research on the crystallization thereof. For example, CN113999182A and US4937348A mainly use the intermittent cooling crystallization method of mixed solvents to prepare the product. For products in the cosmetics industry or high-end industries, to ensure that the product meets the quality requirements of low residual solvents, the conventional crystallization process generally first forms large crystal particles, and then the material is crushed. This crystallization process is complicated, time-consuming and high in cost. SUMMARY

[0006] In view of the deficiencies in the prior art, the present application provides a semi-continuous collision jet crystallization method. The reaction liquid and the crystallization solvent are added to the jet mixer, and then the mixture is cooled and crystallized in the batch crystallization kettle to obtain the final product. This method can directly obtain a product with higher yield, narrower particle size distribution, larger specific surface area, higher purity and lower solvent residue.

[0007] According to a first aspect of the present application, a crystallization method of a benzotriazole compound is provided, which comprises mixing a reaction liquid containing the benzotriazole compound with a crystallization solvent in a jet mixer, and then crystallizing the mixed stream in a crystallization kettle.

[0008] In some embodiments, the feed weight ratio of the reaction solution to the crystallization solvent is (0.5-5):1, preferably (1-2):1. In some specific embodiments, the feed weight ratio of the reaction solution to the crystallization solvent is 0.5:1, 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, 3:1, 4:1, 5:1, or any value between them.

[0009] In some embodiments, the crystallization solvent comprises a C1-C3 alcohol compound, such as methanol, ethanol, or propanol. In some preferred embodiments, the crystallization solvent is ethanol.

[0010] In some embodiments, the mixing temperature is 25-60°C, preferably 30-50°C. In some specific embodiments, the mixing temperature is 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 60°C, or any value between them.

[0011] In some embodiments, the mixing time is 0.5-5 hours, preferably 1-1.5 hours. In some specific embodiments, the mixing time is 0.5 hours, 1 hour, 1.5 hours, 2 hours, 3 hours, 4 hours, 5 hours, or any value between them.

[0012] In some embodiments, the crystallization is cooling crystallization.

[0013] In some preferred embodiments, the crystallization temperature is reduced from 25-60°C to 10-20°C, for example to 10°C, 12°C, 14°C, 16°C, 18°C, 20°C, or any value between them. In some preferred embodiments, the crystallization temperature is reduced from 30-50°C to 10-20°C.

[0014] In some embodiments, the crystallization time is 0.5-5 hours, preferably 1-2 hours. In some specific embodiments, the mixing time is 0.5 hours, 1 hour, 1.5 hours, 2 hours, 3 hours, 4 hours, 5 hours, or any value between them.

[0015] In some embodiments, the jet mixer employs a corrugated plate structure. A jet refers to liquid being ejected from a nozzle or orifice, breaking free from the constraints of solid boundaries, and diffusing within a liquid or gas.

[0016] In some embodiments, the crystallization vessel is an indirect crystallization vessel. Intermittent crystallization is a single-tank, periodic batch operation, involving the intermittent addition of materials during the operation.

[0017] In some embodiments, the crystallization method further includes washing and drying the crystallized product.

[0018] In some embodiments, the solvent used for washing includes C1-C3 alcohol compounds, such as methanol, ethanol, or propanol. In some preferred embodiments, the solvent used for washing is ethanol.

[0019] In some embodiments, the solvent used for washing is the same as the solvent used for crystallization.

[0020] In some embodiments, the washing is performed more than twice, preferably two to four times.

[0021] In some embodiments, the benzotriazole compound is selected from compounds with the structure shown in Formula I.

[0022]

[0023] R1, R3, R5, and R7 are each independently selected from hydrogen or C1-C3 alkyl groups, R4 is selected from C1-C3 alkylene groups, and R2 and R6 are selected from C4-C10 straight-chain or branched alkyl groups.

[0024] In some embodiments, R1, R3, R5, and R7 are each independently selected from hydrogen, methyl, ethyl, or propyl, preferably hydrogen.

[0025] In some embodiments, R4 is selected from methylene, ethylene, or propylene, preferably methylene.

[0026] In some embodiments, R2 and R6 are each independently selected from C6-C10 branched alkyl groups, such as sec-hexyl, pterhexyl, isohexyl, sec-heptyl, pterhexyl, isoheptyl, sec-octyl, pteroctyl, isooctyl, sec-nonyl, pteroctyl, isonyl, sec-decyl, pteroctyl, or isodecyl.

[0027] In some embodiments, the benzotriazole compound is selected from compounds with the structure shown in Formula II, namely 2,2'-methylene-bis(4-tert-octyl-6-benzotriazolyl)phenol, also known as ultraviolet absorber UV-360.

[0028]

[0029] According to a second aspect of the present invention, an apparatus for the crystallization method described in the first aspect is provided, comprising a jet mixer and a crystallization vessel connected to each other, the jet mixer being connected to a reaction liquid feed pipe and a crystallization solvent feed pipe, and the crystallization vessel being connected to a discharge pipe.

[0030] In some embodiments, the jet mixer employs a corrugated plate structure.

[0031] In some embodiments, the crystallization vessel is an indirect crystallization vessel.

[0032] According to a third aspect of the invention, an article containing a benzotriazole compound is provided, which is obtained by the crystallization method described in the first aspect or the apparatus described in the second aspect.

[0033] In some embodiments, the particle size of the benzotriazole compound is 20-50 μm, preferably 20-30 μm.

[0034] In some embodiments, the purity of the benzotriazole compound is ≥98%, preferably ≥99%.

[0035] In some embodiments, the yield of the benzotriazole compound is ≥94%, preferably ≥96%.

[0036] In some embodiments, the solvent residue in the article is ≤500ppm, preferably ≤300ppm, and more preferably 200-250ppm.

[0037] According to a fourth aspect of the invention, the use of the crystallization method described in the first aspect or the apparatus described in the second aspect in the production of benzotriazole compounds is provided.

[0038] In some embodiments, the crystallization method or apparatus is used for the production of benzotriazole compounds in the cosmetics industry.

[0039] In some embodiments, the benzotriazole compound is selected from compounds with the structure shown in Formula II.

[0040]

[0041] R1, R3, R5, and R7 are each independently selected from hydrogen or C1-C3 alkyl groups, R4 is selected from C1-C3 alkylene groups, and R2 and R6 are selected from C4-C10 straight-chain or branched alkyl groups.

[0042] In some embodiments, R1, R3, R5, and R7 are each independently selected from hydrogen, methyl, ethyl, or propyl, preferably hydrogen.

[0043] In some embodiments, R4 is selected from methylene, ethylene, or propylene, preferably methylene.

[0044] In some embodiments, R2 and R6 are each independently selected from C6-C10 branched alkyl groups, such as sec-hexyl, pterhexyl, isohexyl, sec-heptyl, pterhexyl, isoheptyl, sec-octyl, pteroctyl, isooctyl, sec-nonyl, pteroctyl, isonyl, sec-decyl, pteroctyl, or isodecyl.

[0045] In some embodiments, the benzotriazole compound is selected from compounds with the structure shown in Formula II, namely 2,2'-methylene-bis(4-tert-octyl-6-benzotriazolyl)phenol, also known as ultraviolet absorber UV-360.

[0046]

[0047] In the production of benzotriazole compounds, the crystallization method of this invention can achieve a higher yield, larger specific surface area, higher purity, and lower solvent residue in a single crystallization process. When applied to the cosmetics industry, it results in a shorter process flow and lower cost. The process flow of this invention is shortened, material loss is reduced, and product yield is improved. Attached Figure Description

[0048] Figure 1 A schematic diagram of a crystallization method according to some embodiments of the present invention is shown. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention in any way. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure. Such structures and techniques have also been described in many publications.

[0050] This invention relates to a method for crystallizing benzotriazole compounds and an apparatus for the crystallization method, such as... Figure 1 As shown.

[0051] In some embodiments, the crystallization method of the present invention includes the following steps:

[0052] (1) Mixing: The reaction solution containing benzotriazole compounds and the crystallization solvent are fed into the jet mixer respectively; the temperature of the jet mixer is controlled at 25-60℃ (preferably 30-50℃), and the reaction solution and ethanol are fully mixed in the mixer;

[0053] (2) Crystallization aging: The reaction solution is fully mixed in the jet mixer and then enters the crystallization tank for crystallization aging;

[0054] (3) Filtration and washing: Filtration and washing of the filter cake to obtain the crystallized product.

[0055] In some embodiments, in step (1), the weight ratio of the reaction solution to the crystallization solvent is (0.5-5):1, preferably 1-2:1, for example 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1.

[0056] In some embodiments, in step (2), the crystallization temperature is controlled to decrease from 25-60°C (preferably from 30-50°C) to 10-20°C, and the crystallization time is 0.5-5h, preferably 1-2h.

[0057] In some embodiments, in step (1), the crystallization solvent includes C1-C3 alcohol compounds, such as methanol, ethanol or propanol, preferably ethanol.

[0058] In some embodiments, the solvent used for washing in step (3) is the same as the crystallization solvent; in order to improve product purity and reduce solvent residue, the washing is performed twice.

[0059] In some embodiments, the jet mixer has a corrugated plate structure.

[0060] The reagents and / or materials used in the following examples are commercially available or can be synthesized by known methods.

[0061] The UV360 reaction solution used in the following comparative examples and embodiments was obtained through the following steps:

[0062] (1) Add 5g of paraformaldehyde, 80g of 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, and 25g of diethylamine to a four-necked flask. After the addition is complete, start heating and keep the temperature at 130-140℃ for 2 hours. Then add 3g of sodium hydroxide, slowly heat to 180-190℃ and react for 4 hours. Finally, add 100g of toluene as solvent.

[0063] (2) Adjust the pH of the reaction solution to neutral using glacial acetic acid, and wash with 100ml of water to obtain the UV-360 reaction solution.

[0064] Comparative Example 1

[0065] Step 1: Add 180g of UV360 reaction solution (containing 100g of toluene, 80g of UV360 reaction product and reaction impurities) and 100g of ethanol to the four-necked flask. Turn on the stirrer and heat to about 75℃ to dissolve the solution.

[0066] Step 2: Control the slow precipitation of materials by cooling down. The total cooling time is divided into three steps: keep the temperature at about 70℃ for 3 hours, cool down from 70℃ to 40℃ for 6 hours, and cool down from 40℃ to 20℃ for about 4 hours. The total time is 13 hours to cool down to 20℃.

[0067] Step 3: The resulting crystallization solution was then filtered using a Buchner funnel, and the filter cake was washed twice with 160 ml of ethanol. After washing, the filter cake was dried to obtain the UV360 dried product.

[0068] Step 4: Crush the dried UV360 product using a pulverizer to obtain the final UV360 product.

[0069] The experimental conditions were repeated five times, with an average yield of 94.68%.

[0070] Example 1

[0071] Step 1: Add 180g of UV360 reaction solution (containing 100g of toluene, 80g of UV360 product and reaction impurities) and 100g of ethanol to the jet mixer. Control the addition rate so that it is completed in 1-1.5h. Control the temperature of the jet mixer to 40℃. The total time is 1h. The mixture enters the four-necked bottle through the jet mixer.

[0072] Step 2: Slowly cool the crystallizing liquid in the four-necked flask to precipitate it out, taking a total of 2 hours to cool it down to 20°C.

[0073] Step 3: The resulting crystallization solution is then filtered using a Buchner funnel. The filter cake is washed twice with 160 ml of ethanol. The washed filter cake is then dried to obtain the UV360 finished product.

[0074] The experimental conditions were repeated five times, with an average yield of 96.59%.

[0075] Example 2

[0076] Step 1: Add 180g of UV360 reaction solution (containing 100g of toluene, 80g of UV360 product and reaction impurities) and 100g of ethanol to the jet mixer. Control the addition rate so that it is completed in 1-1.5h. Control the temperature of the jet mixer to 50℃. The total time is 1h. The mixture enters the four-necked bottle through the jet mixer.

[0077] Step 2: Slowly cool the crystallizing liquid in the four-necked flask to precipitate it out, taking a total of 2 hours to cool it down to 20°C.

[0078] Step 3: The resulting crystallization solution is then filtered using a Buchner funnel. The filter cake is washed twice with 160 ml of ethanol. The washed filter cake is then dried to obtain the UV360 finished product.

[0079] The experimental conditions were repeated five times, with an average yield of 96.13%.

[0080] Example 3

[0081] Step 1: Add 180g of UV360 reaction solution (containing 100g of toluene, 80g of UV360 product and reaction impurities) and 100g of ethanol to the jet mixer. Control the addition rate so that it is completed in 1-1.5h. Control the temperature of the jet mixer to 40℃. The total time is 1h. The mixture enters the four-necked bottle through the jet mixer.

[0082] Step 2: Slowly cool the crystallizing liquid in the four-necked flask to precipitate it out, taking a total of 2 hours to cool it down to 10℃.

[0083] Step 3: The resulting crystallization solution is then filtered using a Buchner funnel. The filter cake is washed twice with 160 ml of ethanol. The washed filter cake is then dried to obtain the UV360 finished product.

[0084] The experimental conditions were repeated five times, with an average yield of 97.06%.

[0085] Example 4

[0086] Step 1: Add 180g of UV360 reaction solution (containing 100g of toluene, 80g of UV360 product and reaction impurities) and 180g of ethanol to the jet mixer. Control the addition rate so that it is completed in 1-1.5h. Control the temperature of the jet mixer to 40℃. The total time is 1h. The mixture enters the four-necked bottle through the jet mixer.

[0087] Step 2: Slowly cool the crystallizing liquid in the four-necked flask to precipitate it out, taking a total of 2 hours to cool it down to 20°C.

[0088] Step 3: The resulting crystallization solution is then filtered using a Buchner funnel. The filter cake is washed twice with 160 ml of ethanol. The washed filter cake is then dried to obtain the UV360 finished product.

[0089] The experimental conditions were repeated five times, with an average yield of 95.43%.

[0090] Example 5

[0091] Step 1: Add 180g of UV360 reaction solution (containing 100g of toluene, 80g of UV360 product and reaction impurities) and 270g of ethanol to the jet mixer. Control the addition rate so that it is completed in 1-1.5h. Control the temperature of the jet mixer to 40℃. The total time is 1h. The mixture enters the four-necked bottle through the jet mixer.

[0092] Step 2: Slowly cool the crystallizing liquid in the four-necked flask to precipitate it out, taking a total of 2 hours to cool it down to 20°C.

[0093] Step 3: The resulting crystallization solution is then filtered using a Buchner funnel. The filter cake is washed twice with 160 ml of ethanol. The washed filter cake is then dried to obtain the UV360 finished product.

[0094] The experimental conditions were repeated five times, with an average yield of 94.86%.

[0095] Example 6

[0096] Step 1: Add 180g of UV360 reaction solution (containing 100g of toluene, 80g of UV360 product and reaction impurities) and 100g of ethanol to the jet mixer. Control the addition rate so that it is completed in 1-1.5h. Control the temperature of the jet mixer to 20℃. The total time is 1h. The mixture enters the four-necked bottle through the jet mixer.

[0097] Step 2: Slowly cool the crystallizing liquid in the four-necked flask to precipitate it out, taking a total of 2 hours to cool it down to 20°C.

[0098] Step 3: The resulting crystallization solution is then filtered using a Buchner funnel. The filter cake is washed twice with 160 ml of ethanol. The washed filter cake is then dried to obtain the UV360 finished product.

[0099] The experimental conditions were repeated five times, with an average yield of 96.38%.

[0100] Example 7

[0101] Step 1: Add 180g of UV360 reaction solution (containing 100g of toluene, 80g of UV360 product and reaction impurities) and 100g of ethanol to the jet mixer. Control the addition rate so that it is completed in 1-1.5h. Control the temperature of the jet mixer to 55℃. The total time is 1h. The mixture enters the four-necked bottle through the jet mixer.

[0102] Step 2: Slowly cool the crystallizing liquid in the four-necked flask to precipitate it out, taking a total of 2 hours to cool it down to 20°C.

[0103] Step 3: The resulting crystallization solution is then filtered using a Buchner funnel. The filter cake is washed twice with 160 ml of ethanol. The washed filter cake is then dried to obtain the UV360 finished product.

[0104] The experimental conditions were repeated five times, with an average yield of 96.54%.

[0105] Example 8

[0106] Step 1: Add 180g of UV360 reaction solution (containing 100g of toluene, 80g of UV360 product and reaction impurities) and 100g of ethanol to the jet mixer. Control the addition rate so that it is completed in 1-1.5h. Control the temperature of the jet mixer to 40℃. The total time is 1h. The mixture enters the four-necked bottle through the jet mixer.

[0107] Step 2: Slowly cool the crystallizing liquid in the four-necked flask to precipitate it out, taking a total of 0.5 hours to cool it down to 20°C.

[0108] Step 3: The resulting crystallization solution is then filtered using a Buchner funnel. The filter cake is washed twice with 160 ml of ethanol. The washed filter cake is then dried to obtain the UV360 finished product.

[0109] The experimental conditions were repeated five times, with an average yield of 96.04%.

[0110] Example 9

[0111] Step 1: Add 180g of UV360 reaction solution (containing 100g of toluene, 80g of UV360 product and reaction impurities) and 100g of ethanol to the jet mixer. Control the addition rate so that it is completed in 1-1.5h. Control the temperature of the jet mixer to 40℃. The total time is 1h. The mixture enters the four-necked bottle through the jet mixer.

[0112] Step 2: Slowly cool the crystallizing liquid in the four-necked flask to precipitate it out, taking a total of 4 hours to cool it down to 20°C.

[0113] Step 3: The resulting crystallization solution is then filtered using a Buchner funnel. The filter cake is washed twice with 160 ml of ethanol. The washed filter cake is then dried to obtain the UV360 finished product.

[0114] The experimental conditions were repeated five times, with an average yield of 96.49%.

[0115] Example 10

[0116] Step 1: Add 180g of UV360 reaction solution (containing 100g of toluene, 80g of UV360 product and reaction impurities) and 100g of methanol to the jet mixer. Control the addition rate so that it is completed in 1-1.5h. Control the temperature of the jet mixer to 40℃. The total time is 1h. The mixture enters a four-necked flask through the jet mixer.

[0117] Step 2: Slowly cool the crystallizing liquid in the four-necked flask to precipitate it out, taking a total of 2 hours to cool it down to 20°C.

[0118] Step 3: The resulting crystallization solution is then filtered using a Buchner funnel. The filter cake is washed twice with 160 ml of ethanol. The washed filter cake is then dried to obtain the UV360 finished product.

[0119] The experimental conditions were repeated five times, with an average yield of 95.81%.

[0120] Test case

[0121] 1. Detection of residual solvent

[0122] Weigh 400-500 mg of sample (record the accurate value) into a 25 mL volumetric flask, dissolve in 4 mL of dichloromethane, dilute to volume with methanol, shake well, let stand for 5 min, filter the supernatant and inject the sample. After sampling, record the peak area of ​​the target peak and the sample volume, and calculate the solvent content by substituting into the calibration curve. The detection conditions are shown in Table 1 below.

[0123] Table 1

[0124] 2. Detection of particle size or specific surface area

[0125] Instrument: Dandong Better Laser Particle Size Analyzer

[0126] Instrument parameters: Rotation speed 800 rpm, non-ultrasonic, medium: water

[0127] Dispersant: Tween 80

[0128] Weigh 0.5-1.0g of sample into a beaker, add water to dissolve it. During the dissolution process, add Tween 80 dispersant to ensure the sample is evenly dispersed in the water. Then turn on the instrument. Once the instrument is ready, use a dropper to add the dispersed sample into the sample cell. When the refractive index of the instrument is in the green area, the instrument will start automatic detection.

[0129] 3. Purity testing

[0130] Purity was tested according to the testing conditions shown in Table 2 below.

[0131] Table 2

[0132]

[0133] The results of solvent residue, medium particle size, purity and yield of UV-360 prepared in each example and comparative example are shown in Table 3 below.

[0134] Table 3

[0135] Solvent residue, ppm Medium particle size, pm Purity, % Yield, % Comparative Example 1 450 26.58 99.09 94.68 Example 1 204 28.45 99.86 96.59 Example 2 198 25.97 99.67 96.13 Example 3 207 24.78 99.87 97.06 Example 4 275 24.96 99.78 95.43 Example 5 261 22.84 99.89 94.86 Example 6 489 20.18 98.43 96.38 Example 7 275 49.53 99.82 96.54 Example 8 248 23.84 99.28 96.04 Example 9 209 29.14 99.72 96.49 Example 10 297 34.82 99.04 95.81

[0136] As can be seen from the results of Comparative Example 1 and the Examples and Table 3 above, the process flow, equipment required, and crystallization control conditions of the method of Comparative Example 1 are more complex. The crystallization method of this application can obtain UV360 products that meet quality inspection standards in one crystallization, with a higher product yield, and significantly reduces the mixing temperature of the reaction solution and crystallization solvent, while shortening the crystallization time. The process flow is shorter and the cost is lower.

[0137] Further, as can be seen from the various embodiments and the results in Table 3, in the crystallization method of this application, by controlling the mixing ratio of the reaction solution and ethanol, the mixing temperature, and the crystallization temperature within a specific range, products with smaller particle size, higher purity, and lower solvent residue can be obtained.

[0138] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A method for crystallizing a benzotriazole compound, the method comprising mixing a reaction solution containing the benzotriazole compound with a crystallization solvent in a jet mixer, and then crystallizing the mixed stream in a crystallization vessel; The feed weight ratio of the reaction solution to the crystallization solvent is (0.5-5):1; The mixing temperature is 25-60℃, and the mixing time is 0.5-5h; The crystallization solvent is a C1-C3 alcohol compound; The crystallization is a cooling crystallization; the crystallization temperature is reduced from 25-60℃ to 10-20℃; the crystallization time is 0.5-5 hours. The apparatus used in the crystallization method includes a jet mixer and a crystallization vessel that are interconnected. The jet mixer is connected to a reaction liquid feed pipe and a crystallization solvent feed pipe. The crystallization vessel is connected to a discharge pipe. The jet mixer adopts a corrugated plate structure, and the crystallization vessel is an indirect crystallization vessel. The benzotriazole compounds are selected from compounds with the structure shown in Formula I. in, R1, R3, R5, and R7 are each independently selected from hydrogen or C1-C3 alkyl groups, R4 is selected from C1-C3 alkylene groups, and R2 and R6 are selected from C4-C10 straight-chain or branched alkyl groups.

2. The crystallization method according to claim 1, characterized in that, The feed weight ratio of the reaction solution to the crystallization solvent is (1-2):1; The crystallization solvent is ethanol.

3. The crystallization method according to claim 1, characterized in that, The mixing temperature is 30-50°C; and / or The mixing time is 1-1.5 hours.

4. The crystallization method according to any one of claims 1-3, characterized in that, The crystallization temperature is reduced from 30-50℃ to 10-20℃; The crystallization time is 1-2 hours.

5. The crystallization method according to any one of claims 1-3, characterized in that, The crystallization method further includes washing and drying the crystallized product.

6. The crystallization method according to claim 5, characterized in that, The solvents used for washing include C1-C3 alcohol compounds.

7. The crystallization method according to claim 5, characterized in that, The solvent used for the washing process is ethanol.

8. The crystallization method according to claim 5, characterized in that, The solvent used for washing is the same as the solvent used for crystallization.

9. The crystallization method according to claim 5, characterized in that, The washing is performed more than twice.

10. The crystallization method according to claim 5, characterized in that, The washing process is performed 2-4 times.

11. The crystallization method according to any one of claims 1-3, characterized in that, The benzotriazole compounds are selected from compounds with the structure shown in Formula II.

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