Preparation method of p-benzoquinone dioxime with controllable morphology

Abstract

The application provides a preparation method of controllable morphology p-benzoquinone dioxime, which comprises the following steps: 1) adding crude p-benzoquinone dioxime into a first solvent to perform first reflux treatment, and obtaining a first solution; 2) adding a second solvent into the first solution to perform second reflux treatment, and obtaining a second solution; 3) performing post-treatment on the second solution to obtain pure p-benzoquinone dioxime; wherein the solubility of the p-benzoquinone dioxime in the first solvent is less than 0.01 g / L at 25 DEG C, and the solubility of the p-benzoquinone dioxime in the second solvent is greater than 10 g / L. The method can effectively solve the problems of single morphology, uneven particle size and unstable properties of the current p-benzoquinone dioxime.

Description

Technical Field

[0001] This invention relates to a method for preparing morphology-controllable p-benzoquinone dioxime, belonging to the field of chemical raw material production. Background Technology

[0002] p-Benzoquinone dioxime is a high-performance crosslinking agent with excellent dispersion in rubber compounds, fast vulcanization speed, high tensile strength of vulcanized rubber, heat resistance, weather resistance, ozone resistance, and good electrical insulation properties, making it widely used in the rubber industry. Because p-benzoquinone dioxime imparts excellent properties such as high temperature resistance, aging resistance, high toughness, and high adhesive strength to materials, it is particularly suitable for butyl rubber, natural rubber, ethylene propylene rubber, styrene-butadiene rubber, and polysulfide rubber, which require high tensile strength and fast vulcanization speed. Furthermore, p-benzoquinone dioxime can be used as a polymerization inhibitor for acrylic acid, an adhesive for hot-melt bonding of metals and glass, a crosslinking regulator for olefin copolymers, an organic monomer stabilizer, a self-vulcanizing adhesive, and can also improve the thermal resistance of polyester fiber tire cords and activate oxidants. Currently, the main industrial method for producing p-benzoquinone dioxime is as follows: under acidic conditions at 0°C, sodium nitrite is reacted with a phenol solution dissolved in 30% NaOH to produce p-benzoquinone monooxime, which is then oximated by adding hydroxylamine to obtain the final product p-benzoquinone dioxime.

[0003] When applied, p-benzoquinone dioxime typically exists in its natural morphology. However, diverse morphologies are required for various applications. The p-benzoquinone dioxime prepared by the aforementioned method only exists as coarse particles with a limited morphology. Furthermore, due to the high impurity content of these coarse particles, the purity is generally ≤95%, resulting in uneven particle size and easy hygroscopicity, leading to unstable properties. Therefore, providing high-purity p-benzoquinone dioxime with uniform particle size and diverse morphologies is of significant practical importance. Summary of the Invention

[0004] This invention provides a method for preparing morphology-controllable p-benzoquinone dioxime. This method can control the morphology of p-benzoquinone dioxime to meet the specific application requirements, resulting in needle-like, powdery, or granular forms. The prepared p-benzoquinone dioxime has uniform particle size and high purity, which is beneficial to its storage stability. This method effectively solves the current problems of single morphology, uneven particle size, and unstable properties of p-benzoquinone dioxime.

[0005] This invention provides a method for preparing morphology-controllable p-benzoquinone dioxime, comprising the following steps:

[0006] 1) Add crude p-benzoquinone dioxime to the first solvent and perform a first reflux treatment to obtain a first solution;

[0007] 2) Add a second solvent to the first solution and perform a second reflux treatment to obtain a second solution;

[0008] 3) The second solution was post-treated to obtain pure p-benzoquinone dioxime;

[0009] Specifically, at 25°C, the solubility of p-benzoquinone dioxime in the first solvent is less than 0.01 g / L, and the solubility of p-benzoquinone dioxime in the second solvent is greater than 10 g / L.

[0010] According to one embodiment of the present invention, the mass ratio of the crude p-benzoquinone dioxime to the first solvent is 1:(7-15).

[0011] According to one embodiment of the present invention, the mass ratio of the first solvent to the second solvent is 1:(2-4).

[0012] According to one embodiment of the present invention, the first solvent includes at least one of distilled water, petroleum ether, dichloromethane, dichloroethane, and glacial acetic acid.

[0013] According to one embodiment of the present invention, the second solvent includes at least one selected from ethanol, diethyl ether, ethyl acetate, N,N-dimethylformamide, and dimethyl sulfoxide.

[0014] According to one embodiment of the present invention, the second solvent is added to the first solution, and after the crude p-benzoquinone dioxime is completely dissolved, the second solvent is added to the system to obtain the second solution.

[0015] According to one embodiment of the present invention, the volume of the second solvent added is 10-20 ml.

[0016] According to one embodiment of the present invention, in the first reflux process, the rotation speed is 500-800 rpm; and / or, in the second reflux process, the rotation speed is 500-800 rpm.

[0017] According to one embodiment of the present invention, in the first reflux process, the reflux time is 10-20 min.

[0018] According to one embodiment of the present invention, in the second reflux process, the reflux time is 10-20 min.

[0019] In the preparation method of this invention, the synergistic effect of the first solvent and the second solvent can, on the one hand, control the macroscopic morphology and particle size of p-benzoquinone dioxime, and prepare needle-shaped, powdered or granular p-benzoquinone dioxime with different particle sizes according to application requirements, effectively solving the problem of the single morphology of existing products; on the other hand, it can also remove p-benzoquinone dioxime impurities, improve the uniformity of particle size and product purity, and obtain a stable pure p-benzoquinone dioxime, which is of great significance for practical industrial applications. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. 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.

[0021] This invention provides a method for preparing morphology-controllable p-benzoquinone dioxime, comprising the following steps:

[0022] 1) Add crude p-benzoquinone dioxime to the first solvent and perform a first reflux treatment to obtain a first solution;

[0023] 2) Add a second solvent to the first solution and perform a second reflux treatment to obtain a second solution;

[0024] 3) The second solution was post-treated to obtain pure p-benzoquinone dioxime;

[0025] Specifically, at 25°C, the solubility of p-benzoquinone dioxime in the first solvent is less than 0.01 g / L, and the solubility of p-benzoquinone dioxime in the second solvent is greater than 10 g / L.

[0026] It should be explained that the method described above in this invention is specifically a purification method for crude p-benzoquinone dioxime, and this purification method is applicable to crude p-benzoquinone dioxime prepared by any method. Specifically, the purity (liquid chromatography) of the crude p-benzoquinone dioxime in this invention is not higher than 95%.

[0027] In this invention, at 25°C, a maximum of 0.01 g of p-benzoquinone dioxime can be dissolved in 1 L of the first solvent, and at least 10 g of p-benzoquinone dioxime can be dissolved in 1 L of the second solvent. P-benzoquinone dioxime is almost insoluble in the first solvent but soluble in the second solvent. Therefore, in step 1), adding the first solvent promotes the precipitation of p-benzoquinone dioxime crystals; in step 2), adding the second solvent to the first solution ensures the dissolution of p-benzoquinone dioxime. The post-treatment in step 3) includes at least hot filtration, static crystallization, filtration, and drying. Through these treatments, impurities in the crude p-benzoquinone dioxime are removed, which is beneficial for improving purity. During static treatment, the presence of the first solvent and the decrease in solution temperature both promote the precipitation of p-benzoquinone dioxime crystals, increasing the yield. Furthermore, due to the different polarities of the first and second solvents, the morphology of p-benzoquinone dioxime precipitated in different solvent combinations also varies.

[0028] The preparation method of this invention can obtain pure p-benzoquinone dioxime with controllable particle size and a purity of not less than 98% in high yield. Furthermore, the morphology of the final pure p-benzoquinone dioxime can be adjusted during the purification process to achieve needle-like, powdered, or granular forms that meet application requirements. Needle-like p-benzoquinone dioxime can be used in rubber vulcanization, reacting with oxidants as a rubber vulcanizing agent; powdered p-benzoquinone dioxime can be used in chemical analysis, for example, as a reagent for determining nickel; and granular p-benzoquinone dioxime can be used in adhesives, for example, for bonding rubber to metals.

[0029] According to the inventors' research, the mass ratio of the crude p-benzoquinone dioxime to the first solvent is 1:(7-15). The first solvent can promote the precipitation of p-benzoquinone dioxime crystals dissolved in the second solvent. If the amount added is too small, it will be difficult for the pure p-benzoquinone dioxime crystals to precipitate, or the precipitation will be incomplete, resulting in a decrease in yield; while if the amount added is too large, it will lead to solvent waste due to economic cost considerations.

[0030] Further research revealed that the mass ratio of the first solvent to the second solvent was 1:(2-4). Insufficient addition of the second solvent would result in incomplete dissolution of p-benzoquinone dioxime, thus promoting the precipitation of p-benzoquinone dioxime crystals under the action of the first solvent, reducing the purity and yield of p-benzoquinone dioxime. When the mass of the second solvent was 2-4 times higher than that of the first solvent, besides making it difficult to control solvent costs, more importantly, the excessive amount of the second solvent would inhibit the precipitation effect of the first solvent on the crystals, making it difficult for p-benzoquinone dioxime to precipitate, ultimately leading to a decrease in yield.

[0031] Therefore, the preparation method of adding the first solvent first and then the second solvent is beneficial for precisely controlling the amount of the second solvent added, avoiding the addition of too much or too little second solvent, which would affect the quality and yield of the pure p-benzoquinone dioxime. When the mass ratio of the crude p-benzoquinone dioxime to the first solvent is simultaneously limited to 1:(7-15), and the mass ratio of the first solvent to the second solvent is 1:(2-4), the purity and yield of p-benzoquinone dioxime can be improved.

[0032] In this invention, the first solvent includes at least one of distilled water, petroleum ether, dichloromethane, dichloroethane, and glacial acetic acid.

[0033] In this invention, the second solvent includes at least one of ethanol, diethyl ether, ethyl acetate, N,N-dimethylformamide, and dimethyl sulfoxide.

[0034] In practice, by matching the types of the first and second solvents, the particle size of p-benzoquinone dioxime can be adjusted and its purity controlled. For example, when the combination of the first and second solvents is distilled water and anhydrous ethanol, the particle size of p-benzoquinone dioxime can be effectively reduced, and its purity improved.

[0035] Furthermore, the morphology of p-benzoquinone dioxime can be controlled by matching the types of the first and second solvents. For example, to obtain needle-shaped p-benzoquinone dioxime, the first solvent can be distilled water and the second solvent can be anhydrous ethanol; or the first solvent can be petroleum ether and the second solvent can be anhydrous ethanol; or the first solvent can be dichloromethane and the second solvent can be diethyl ether; or the first solvent can be dichloroethane and the second solvent can be diethyl ether; or the first solvent can be dichloroethane and the second solvent can be anhydrous ethanol. To obtain powdered p-benzoquinone dioxime, the first solvent can be distilled water and the second solvent can be diethyl ether; or the first solvent can be glacial acetic acid and the second solvent can be N,N-dimethylformamide. To obtain particulate p-benzoquinone dioxime, the first solvent can be glacial acetic acid and the second solvent can be dimethyl sulfoxide; or the first solvent can be petroleum ether and the second solvent can be ethyl acetate.

[0036] In this invention, the second solvent is added to the first solution, and after the crude p-benzoquinone dioxime is completely dissolved, the second solvent is added to the system to obtain the second solution.

[0037] In this invention, the volume of the second solvent added is 10-20 ml. Limiting the amount of the second solvent added serves two purposes: firstly, it avoids insufficient addition of the second solvent, which would lead to oversaturation of the solution and easy precipitation of crystals; secondly, it avoids excessive addition of the second solvent, which would reduce the amount of p-benzoquinone dioxime crystals precipitated.

[0038] The present invention does not limit the stirring speed in the reflux treatment. For example, in the first reflux treatment, the stirring speed is 500-800 rpm; and / or, in the second reflux treatment, the stirring speed is 500-800 rpm.

[0039] In one specific implementation, the reflow time in the first reflow process is 10-20 minutes.

[0040] In one specific implementation, the reflow time in the second reflow process is 10-20 minutes.

[0041] In the following examples, high performance liquid chromatography was used to test the purity of p-benzoquinone dioxime; and a laser particle size analyzer was used to test the particle size of the product.

[0042] Comparative Example 1

[0043] The preparation of p-benzoquinone dioxime in this comparative example includes the following steps:

[0044] 1) Preparation of sodium phenolate solution: Add 6.67g sodium hydroxide, 20.7g sodium nitrite, 15.68g phenol and 80ml distilled water to a beaker;

[0045] 2) Preparation of p-benzoquinone monooxime: The above-mentioned sodium phenolate solution was added dropwise to a flask containing 130 ml of 30% sulfuric acid solution under stirring at 0°C. The addition time was 2 h, the reaction temperature was 0°C, and the rotation speed was 500 rpm. After the addition was complete, the mixture was kept at this temperature for another 1 h, then filtered. The filter cake was washed with water to obtain a light brown p-benzoquinone monooxime.

[0046] 3) Preparation of crude p-benzoquinone dioxime: Add p-benzoquinone monooxime to 50 ml of water. Under stirring, add dropwise a hydroxylamine solution prepared from 11.58 g of hydroxylamine hydrochloride and 20 ml of water. The reaction temperature is 60℃, the addition time is 0.5 h, and the rotation speed is 500 rpm. After the addition is complete, maintain the temperature for another 1 h. After the reaction is complete, filter, wash with water, and dry to obtain dark brown coarse granular crude p-benzoquinone dioxime, with a net weight of 18.24 g after drying.

[0047] According to high performance liquid chromatography (HPLC) analysis and comparison with the standard spectrum, the purity of the product obtained in Comparative Example 1 was 92.126%, and the yield was 79.00%.

[0048] Comparative Example 2

[0049] The preparation of p-benzoquinone dioxime in this comparative example includes the following steps:

[0050] 1) 18.24 g of crude p-benzoquinone dioxime was prepared according to the method of Comparative Example 1;

[0051] 2) Add anhydrous ethanol to 18.24g of crude p-benzoquinone dioxime, stir at 500rpm until the crude p-benzoquinone dioxime is completely dissolved, then add 10ml of ethanol, for a total of 600g of anhydrous ethanol, and reflux for 10min.

[0052] 3) Filter while hot to remove impurities. The final filtrate was allowed to stand for crystallization, filtered, and dried to obtain 6.21g of brown coarse granular p-benzoquinone dioxime crystals.

[0053] According to high performance liquid chromatography, the purity of the product obtained in Comparative Example 1 was 98.450%, and the product yield was 34.04%.

[0054] Example 1

[0055] The preparation of p-benzoquinone dioxime in this embodiment includes the following steps:

[0056] 1) 19.13 g of crude p-benzoquinone dioxime was prepared according to the method of Comparative Example 1;

[0057] 2) Add 19.13g of crude p-benzoquinone dioxime to 200g of distilled water, stir and heat to reflux temperature at 500rpm for 10min to obtain the first solution;

[0058] 3) Add anhydrous ethanol to the first solution and stir at 500 rpm until the crude p-benzoquinone dioxime is completely dissolved. Then add 10 ml of ethanol, for a total of 600 g of anhydrous ethanol. Reflux for 10 min to obtain the second solution.

[0059] 4) Filter the second solution while hot to remove impurities. Finally, after static crystallization, filtration and drying, 17.53g of light brown needle-shaped p-benzoquinone dioxime crystals were obtained.

[0060] According to high performance liquid chromatography, the purity of the product obtained in Example 1 was 99.532%, and the product yield was 91.65%.

[0061] Example 2

[0062] The preparation of p-benzoquinone dioxime in this embodiment includes the following steps:

[0063] 1) 20.52 g of crude p-benzoquinone dioxime was prepared according to the method of Comparative Example 1;

[0064] 2) Add 20.52g of crude p-benzoquinone dioxime to 160g of distilled water, stir and heat to reflux temperature at 500rpm for 10min to obtain the first solution;

[0065] 3) Add ether to the first solution and stir at 800 rpm until the crude p-benzoquinone dioxime is completely dissolved. Then add 10 ml of ether, for a total of 320 g of ether. Reflux for 10 min to obtain the second solution.

[0066] 4) Filter the second solution while hot to remove impurities. Finally, after static crystallization, filtration and drying, 18.17g of light brown powdery p-benzoquinone dioxime crystals were obtained.

[0067] According to high performance liquid chromatography, the purity of the product obtained in Example 2 was 99.265%, and the product yield was 88.54%.

[0068] Example 3

[0069] The preparation of p-benzoquinone dioxime in this embodiment includes the following steps:

[0070] 1) 18.96 g of crude p-benzoquinone dioxime was prepared according to the method of Comparative Example 1;

[0071] 2) Add 18.96g of crude p-benzoquinone dioxime to 240g of glacial acetic acid, stir and heat to reflux temperature at 500rpm for 15min to obtain the first solution;

[0072] 3) Add dimethyl sulfoxide to the first solution and stir at 500 rpm until the crude p-benzoquinone dioxime is completely dissolved. Then add 15 ml of dimethyl sulfoxide, for a total of 480 g of dimethyl sulfoxide. Reflux for 15 min to obtain the second solution.

[0073] 4) Filter the second solution while hot to remove impurities. Finally, after static crystallization, filtration and drying, 15.82g of brown granular p-benzoquinone dioxime crystals were obtained.

[0074] According to high performance liquid chromatography, the purity of the product obtained in Example 3 was 98.972%, and the product yield was 83.43%.

[0075] Example 4

[0076] The preparation of p-benzoquinone dioxime in this embodiment includes the following steps:

[0077] 1) 19.43 g of crude p-benzoquinone dioxime was prepared according to the method of Comparative Example 1;

[0078] 2) Add 19.43g of crude p-benzoquinone dioxime to 200g of glacial acetic acid, stir and heat to reflux temperature at 600rpm for 20min to obtain the first solution;

[0079] 3) Add N,N-dimethylformamide to the first solution and stir at 600 rpm until the crude p-benzoquinone dioxime is completely dissolved. Then add 20 ml of N,N-dimethylformamide, for a total of 400 g of N,N-dimethylformamide. Reflux for 20 min to obtain the second solution.

[0080] 4) Filter the second solution while hot to remove impurities. Finally, after static crystallization, filtration and drying, 16.65g of light brown powdery p-benzoquinone dioxime crystals were obtained.

[0081] According to high performance liquid chromatography, the purity of the product obtained in Example 4 was 99.254%, and the product yield was 85.69%.

[0082] Example 5

[0083] The preparation of p-benzoquinone dioxime in this embodiment includes the following steps:

[0084] 1) 19.67 g of crude p-benzoquinone dioxime was prepared according to the method of Comparative Example 1;

[0085] 2) Add 19.67g of crude p-benzoquinone dioxime to 160g of petroleum ether, stir and heat to reflux temperature at 600rpm for 15min to obtain the first solution;

[0086] 3) Add anhydrous ethanol to the first solution and stir at 600 rpm until the crude p-benzoquinone dioxime is completely dissolved. Then add 15 ml of anhydrous ethanol, for a total of 320 g of anhydrous ethanol. Reflux for 15 min to obtain the second solution.

[0087] 4) Filter the second solution while hot to remove impurities. Finally, after static crystallization, filtration and drying, 16.65g of light brown powdery p-benzoquinone dioxime crystals were obtained.

[0088] According to high performance liquid chromatography, the purity of the product obtained in Example 5 was 99.341%, and the product yield was 90.48%.

[0089] Example 6

[0090] The preparation of p-benzoquinone dioxime in this embodiment includes the following steps:

[0091] 1) 19.50 g of crude p-benzoquinone dioxime was prepared according to the method of Comparative Example 1;

[0092] 2) Add 19.50g of crude p-benzoquinone dioxime to 160g of petroleum ether, stir and heat to reflux temperature at 800rpm to obtain the first solution;

[0093] 3) Add ethyl acetate to the first solution and stir at 800 rpm until the crude p-benzoquinone dioxime is completely dissolved. Then add another 20 ml of ethyl acetate, for a total of 640 g of ethyl acetate. Reflux for 20 min to obtain the second solution.

[0094] 4) Filter the second solution while hot to remove impurities. Finally, after static crystallization, filtration and drying, 16.45g of brown granular p-benzoquinone dioxime crystals were obtained.

[0095] According to high performance liquid chromatography, the purity of the product obtained in Example 6 was 98.846%, and the product yield was 84.35%.

[0096] Example 7

[0097] The preparation of p-benzoquinone dioxime in this embodiment includes the following steps:

[0098] 1) 20.51 g of crude p-benzoquinone dioxime was prepared according to the method of Comparative Example 1;

[0099] 2) Add 20.51g of crude p-benzoquinone dioxime to 300g of dichloromethane, stir and heat to reflux temperature at a rate of 600rpm for 15min to obtain the first solution;

[0100] 3) Add ether to the first solution and stir at 700 rpm until the crude p-benzoquinone dioxime is completely dissolved. Then add 15 ml of ether, for a total of 900 g of ether. Reflux for 15 min to obtain the second solution.

[0101] 4) The second solution was filtered while hot to remove impurities. The final filtrate was allowed to stand for crystallization, filtered, and dried to obtain 17.99g of light brown needle-shaped p-benzoquinone dioxime crystals.

[0102] According to high performance liquid chromatography, the purity of the product obtained in Example 7 was 99.616%, and the product yield was 87.70%.

[0103] Example 8

[0104] The preparation of p-benzoquinone dioxime in this embodiment includes the following steps:

[0105] 1) 20.68 g of crude p-benzoquinone dioxime was prepared according to the method of Comparative Example 1;

[0106] 2) Add 20.68g of crude p-benzoquinone dioxime to 240g of dichloroethane, stir and heat to reflux temperature at 600rpm for 10min to obtain the first solution;

[0107] 3) Add ether to the first solution and stir at 800 rpm until the crude p-benzoquinone dioxime is completely dissolved. Then add 10 ml of ether, for a total of 900 g of ether. Reflux for 10 min to obtain the second solution.

[0108] 4) The second solution was filtered while hot to remove impurities. The final filtrate was allowed to stand for crystallization, filtered, and dried to obtain 17.99g of light brown needle-shaped p-benzoquinone dioxime crystals.

[0109] According to high performance liquid chromatography, the purity of the product obtained in Example 8 was 99.558%, and the product yield was 87.32%.

[0110] Example 9

[0111] The preparation of p-benzoquinone dioxime in this embodiment includes the following steps:

[0112] 1) 19.83 g of crude p-benzoquinone dioxime was prepared according to the method of Comparative Example 1;

[0113] 2) Add 19.83g of crude p-benzoquinone dioxime to 240g of dichloroethane, stir and heat to reflux temperature at a rate of 500rpm for 20min to obtain the first solution;

[0114] 3) Add anhydrous ethanol to the first solution and stir at 700 rpm until the crude p-benzoquinone dioxime is completely dissolved. Then add 15 ml of anhydrous ethanol, for a total of 720 g of anhydrous ethanol. Reflux for 20 min to obtain the second solution.

[0115] 4) Filter the second solution while hot to remove impurities. Finally, after static crystallization, filtration and drying, 17.68g of light brown needle-shaped p-benzoquinone dioxime crystals were obtained.

[0116] According to high performance liquid chromatography, the purity of the product obtained in Example 9 was 98.647%, and the product yield was 89.15%.

[0117] 1. Table 1 includes the specific preparation parameters of the above-mentioned embodiments and comparative examples, as well as the characterization parameters of the products.

[0118] Table 1

[0119]

[0120] As shown in Table 1, compared to the crude p-benzoquinone dioxime, the p-benzoquinone dioxime obtained by the combined treatment with the first and second solvents exhibits needle-like, powdery, or granular morphologies with smaller and more uniform particle sizes, which is more conducive to improving the dispersibility of p-benzoquinone dioxime as an additive. Furthermore, the purity of the pure p-benzoquinone dioxime is above 98%, significantly higher than that of the crude p-benzoquinone dioxime (92.126%). According to the results of Comparative Example 2 and Example 1, without the addition of the first solvent, the purity of p-benzoquinone dioxime treated only with the second solvent is improved; however, the morphology and particle size remain unchanged, and the particle size is uneven. This indicates that only when the first and second solvents work synergistically can the morphology and particle size of p-benzoquinone dioxime be controlled.

[0121] 2. Product stability testing

[0122] The samples from Comparative Example 1 and Example 1 were placed under the same temperature and humidity conditions for 6 months. The results showed that Comparative Example 1 exhibited moisture absorption and agglomeration, with a significant deterioration in product dispersibility; while Example 1 still presented regular needle-like crystals, with no obvious moisture absorption and minimal change. The experimental results indicate that, compared to Comparative Example 1, the crystals obtained in Example 1 are less prone to deliquescence, are more suitable for storage, and have more stable properties.

[0123] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention have been clearly and completely described above in conjunction with specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

Claims

1. A method for preparing morphology-controllable p-benzoquinone dioxime, characterized in that, Includes the following steps: 1) Add crude p-benzoquinone dioxime to the first solvent and perform a first reflux treatment to obtain a first solution; 2) Add the second solvent to the first solution and perform a second reflux treatment to obtain a second solution; 3) Post-process the second solution to obtain pure p-benzoquinone dioxime; the first solvent and the second solvent have different polarities; Wherein, at 25°C, the solubility of p-benzoquinone dioxime in the first solvent is less than 0.01 g / L, and the solubility of p-benzoquinone dioxime in the second solvent is greater than 10 g / L; the mass ratio of crude p-benzoquinone dioxime to the first solvent is 1:(7~15); and the mass ratio of the first solvent to the second solvent is 1:(2~4). The first solvent includes at least one of distilled water, petroleum ether, dichloromethane, and dichloroethane; the second solvent includes at least one of anhydrous ethanol, diethyl ether, and ethyl acetate. When it is desired to obtain needle-shaped p-benzoquinone dioxime, the first solvent is distilled water and the second solvent is anhydrous ethanol; or the first solvent is petroleum ether and the second solvent is anhydrous ethanol; or the first solvent is dichloromethane and the second solvent is diethyl ether; or the first solvent is dichloroethane and the second solvent is diethyl ether; or the first solvent is dichloroethane and the second solvent is anhydrous ethanol. When it is desired to obtain powdered p-benzoquinone dioxime, the first solvent is distilled water and the second solvent is diethyl ether; When it is desired to obtain particulate p-benzoquinone dioxime, the first solvent is petroleum ether and the second solvent is ethyl acetate; Add the second solvent to the first solution, and wait until the crude p-benzoquinone dioxime is completely dissolved. Then, add the second solvent to the system; the volume of the second solvent added is 10-20 ml. In the first reflux process, the reflux time is 10-20 minutes.

2. The preparation method according to claim 1, characterized in that, In the first reflux process, the rotation speed is 500-800 rpm; and / or, In the second reflux process, the rotation speed is 500-800 rpm.

3. The preparation method according to claim 1 or 2, characterized in that, In the second reflux process, the reflux time is 10-20 minutes.

Images