Crystallization refining method of high-purity blocky o-phenylenediamine

Abstract

The invention relates to a crystallization refining method of high-purity blocky o-phenylenediamine. The method comprises the following steps: adding an o-phenylenediamine crude product, a good solvent and an anti-solvent into a crystallizer, stirring and heating to 50-70 DEG C to completely dissolve solids, then starting to cool, adding an o-phenylenediamine seed crystal at 30-45 DEG C, growing the crystal at constant temperature for 30-60 minutes, continuing to cool, cooling to 5-20 DEG C, curing the crystal at constant temperature for 30-60 minutes, and then filtering crystal slurry to obtain a filter cake; and leaching the filter cake by using a mixed solvent prepared from a good solvent and an anti-solvent, filtering again, and drying the filter cake to obtain a high-purity blocky o-phenylenediamine crystal product. The purity of the o-phenylenediamine product prepared by the method can reach 99.997% or above, and meanwhile, the obtained o-phenylenediamine is colorless and transparent regular blocky crystals, the product is easy to filter and dry, and is beneficial to storage and transportation, and the market competitiveness of the product is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical engineering crystallization, and in particular relates to a crystallization and purification method for high-purity blocky o-phenylenediamine. Background Art

[0002] O-phenylenediamine (CAS No.: 95-54-5) is also known as 1,2-diaminobenzene, 1,2-phenylenediamine, and its English name is o-Phenylenediamine. Its molecular formula is C6H8N2, and its chemical structure is shown below. It is a colorless monoclinic crystal at room temperature, and its color becomes darker in air and sunlight. It is slightly soluble in cold water, soluble in hot water, and easily soluble in ethanol, ether and chloroform. O-phenylenediamine can be used to synthesize various dyes and pigments, especially azo dyes and phenolic resins. In the field of medicine, o-phenylenediamine can be used as a drug intermediate for the synthesis of antibacterial and anticancer drugs. O-phenylenediamine can also be used as a rubber accelerator, antioxidant and polymer stabilizer to enhance the durability and anti-aging properties of materials.

[0003]

[0004] With the increasing requirements for the purity and crystal morphology of o-phenylenediamine in the downstream, as well as the energy-saving needs of enterprises themselves, it is urgent to develop a new high-purity o-phenylenediamine refining technology with simple process to obtain crystal products with high purity and good morphology, so as to improve the market competitiveness of o-phenylenediamine products.

[0005] Patent CN109879762A reports a method for purifying o-phenylenediamine, which comprises mixing liquid o-phenylenediamine extracted from the top of a distillation tower with deionized water to obtain an o-phenylenediamine aqueous solution, conveying the aqueous solution to a low-position crystallizer to obtain a mixture containing o-phenylenediamine crystals; conveying the mixture to a centrifuge for centrifugation to obtain a filter cake; conveying the filter cake after centrifugation to a melting kettle for melting, conveying the completely melted liquid o-phenylenediamine to a dehydration tower for dehydration, and then conveying it to a flake machine for flake packaging to obtain an o-phenylenediamine product with a purity of 99.999%. Patent CN113307738A reports a multi-stage recrystallization process for o-phenylenediamine, which comprises first preparing a solution of crude phenylenediamine with a solvent as required, then crystallizing and slicing it through a rotary drum flake machine, then separating it through a centrifuge to obtain a filter cake, and then distilling to remove the solvent from the filter cake to finally obtain a refined o-phenylenediamine product with a purity of 99.79%. Through analysis, it was found that patent CN109879762A requires complicated steps of melting, dehydration, slicing, etc.; patent CN113307738A requires multi-stage recrystallization, distillation, slicing, etc. The existing process route is complicated and energy-intensive, resulting in high production costs. In addition, due to the use of slicing technology, the resulting product is an irregular flaky solid with poor product fluidity and particle size distribution, which will bring inconvenience to downstream applications. O-phenylenediamine slice products such asFigure 1 shown.

[0006] Therefore, it is particularly important to develop an o-phenylenediamine refining process with simple process, high product purity and good product morphology to reduce the production cost of o-phenylenediamine and improve the market competitiveness of products. As one of the key purification technologies for fine chemicals, solution crystallization technology has the significant advantages of simple process and low energy consumption, and can effectively regulate the crystal morphology. The present invention discloses a new high-purity o-phenylenediamine refining process based on solution cooling crystallization. By accurately regulating the solution cooling crystallization process parameters, not only a high-purity o-phenylenediamine product can be obtained, but also the o-phenylenediamine product is a regular block crystal. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention provides a method for crystallizing and refining high-purity blocky o-phenylenediamine. Figure 2 and Figure 3 As shown, the product is a regular block crystal, colorless and transparent, with a purity of more than 99.997%; and the product obtained by this method is very easy to filter and dry, which is conducive to storage and transportation, greatly improving the market competitiveness of the product.

[0008] The specific technical solutions of the present invention are as follows:

[0009] A crystallization and purification method for high-purity block o-phenylenediamine comprises the following steps: adding a crude o-phenylenediamine product, a good solvent and an anti-solvent into a crystallizer, stirring and heating to 50-70°C to dissolve all solids, then starting to cool, adding o-phenylenediamine seed crystals at 30-45°C, then growing crystals at a constant temperature for 30-60 minutes, then continuing to cool to 5-20°C, aging crystals at a constant temperature for 30-60 minutes, then filtering the crystal slurry to obtain a filter cake; eluting the filter cake with a mixed solvent prepared with a good solvent and an anti-solvent, filtering again and drying the filter cake to obtain a high-purity block o-phenylenediamine crystal product.

[0010] The good solvent is selected from one of methanol, ethanol, isopropanol, n-propanol, n-butanol, acetonitrile, ethyl acetate, tetrahydrofuran, dichloromethane, chloroform, tetrachloromethane and 1,2-dichloroethane.

[0011] The anti-solvent is selected from one of water, n-hexane, cyclohexane, n-heptane and petroleum ether.

[0012] The mass volume ratio of the crude o-phenylenediamine, the good solvent and the anti-solvent is 1g: 0.5-5mL: 0.5-5mL.

[0013] The amount of o-phenylenediamine seed crystals added is 0.01% to 2% of the initial o-phenylenediamine mass.

[0014] The cooling rate is 1-20°C / h.

[0015] The mixed solvent is a mixed solvent of a good solvent and an anti-solvent, and the volume ratio of the good solvent to the anti-solvent is 1:1-5.

[0016] The mass volume ratio of the crude o-phenylenediamine and the mixed solvent is 1g:0.1-3mL.

[0017] Compared with the prior art, the cooling crystallization refining process of o-phenylenediamine of the present application has the following effects:

[0018] (1) The o-phenylenediamine product obtained by the present invention has a high purity, which can reach more than 99.997%;

[0019] (2) The o-phenylenediamine product obtained by the present invention is a colorless, transparent, and regular block crystal, which is convenient for downstream storage, transportation, and use, has a higher added value, and is far superior to the commercially available irregular slice products;

[0020] (3) The present invention adopts the traditional solution cooling crystallization process, which has a simpler overall process, lower energy consumption, and is easy to implement industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Appearance of commercially available o-phenylenediamine chips.

[0022] Figure 2 Microscope image of the o-phenylenediamine product obtained based on Example 1 of the method of the present invention.

[0023] Figure 3 Microscope image of the o-phenylenediamine product obtained based on Example 2 of the method of the present invention. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0025] The following is a specific embodiment of the present invention:

[0026] Example 1.

[0027] 100 g of crude o-phenylenediamine, 100 mL of methanol and 50 mL of water were added to a crystallizer, stirred and heated to 70°C to dissolve all the solids, then cooled at a rate of 10°C / h, 2 g of o-phenylenediamine seed crystals were added at 45°C, and then the crystals were grown at a constant temperature for 30 minutes, and then the temperature was continued to be reduced at a rate of 10°C / h. After the temperature dropped to 10°C, the crystals were matured at a constant temperature for 30 minutes, and then the slurry was filtered to obtain a filter cake, and the o-phenylenediamine filter cake was rinsed with 100 mL of a methanol-water mixed solvent (50 mL of methanol and 50 mL of water), and the filter cake was dried after filtering again to obtain an o-phenylenediamine block crystal product with a purity of 99.999%.

[0028] Example 2.

[0029] 100 g of crude o-phenylenediamine, 200 mL of ethanol and 100 mL of water were added to a crystallizer, stirred and heated to 65°C to dissolve all the solids, then cooled at a rate of 5°C / h, 1 g of o-phenylenediamine seed crystals were added at 40°C, and then the crystals were grown at a constant temperature for 45 minutes, and then the temperature was continued to be reduced at a rate of 5°C / h. After the temperature dropped to 15°C, the crystals were matured at a constant temperature for 35 minutes, and then the slurry was filtered to obtain a filter cake, and the o-phenylenediamine filter cake was rinsed with 200 mL of ethanol-water mixed solvent (50 mL of ethanol and 150 mL of water), and the filter cake was dried after filtering again to obtain an o-phenylenediamine block crystal product with a purity of 99.997%.

[0030] Example 3.

[0031] 50 g of crude o-phenylenediamine, 25 mL of acetonitrile and 50 mL of water were added to a crystallizer, stirred and heated to 60° C. to dissolve all the solids, then cooled at a rate of 20° C. / h, 0.01 g of o-phenylenediamine seed crystals were added at 30° C., then kept at a constant temperature for 40 minutes, and then cooled at a rate of 20° C. / h. After dropping to 5° C., the crystals were kept at a constant temperature for 60 minutes, and then the slurry was filtered to obtain a filter cake, and the o-phenylenediamine filter cake was rinsed with 50 mL of acetonitrile-water mixed solvent (10 mL of acetonitrile and 40 mL of water), and the filter cake was dried after filtering again to obtain an o-phenylenediamine block crystal product with a purity of 99.997%.

[0032] Example 4.

[0033] 100 g of crude o-phenylenediamine, 100 mL of ethyl acetate and 100 mL of cyclohexane were added into a crystallizer, stirred and heated to 55°C to dissolve all the solids, then cooled at a rate of 15°C / h, 0.01 g of o-phenylenediamine seed crystals were added at 45°C, and then the crystals were grown at a constant temperature for 45 minutes, and then the temperature was continued to be reduced at a rate of 15°C / h. After the temperature dropped to 15°C, the crystals were matured at a constant temperature for 45 minutes, and then the slurry was filtered to obtain a filter cake, and the o-phenylenediamine filter cake was rinsed with 200 mL of ethyl acetate-cyclohexane mixed solvent (100 mL of ethyl acetate and 100 mL of cyclohexane), and the filter cake was dried after filtering again to obtain an o-phenylenediamine block crystal product with a purity of 99.998%.

[0034] Example 5.

[0035] 150 g of crude o-phenylenediamine, 300 mL of tetrahydrofuran and 750 mL of water were added to a crystallizer, stirred and heated to 60° C. to dissolve all the solids, then cooled at a rate of 20° C. / h, 1.5 g of o-phenylenediamine seed crystals were added at 40° C., and then the crystals were grown at a constant temperature for 60 minutes, and then the temperature was continued to be reduced at a rate of 20° C. / h. After the temperature dropped to 10° C., the crystals were matured at a constant temperature for 30 minutes, and then the slurry was filtered to obtain a filter cake, and the o-phenylenediamine filter cake was rinsed with 15 mL of a tetrahydrofuran-water mixed solvent (5 mL of tetrahydrofuran and 10 mL of water), and the filter cake was dried after filtering again to obtain an o-phenylenediamine block crystal product with a purity of 99.999%.

[0036] Example 6.

[0037] 50 g of crude o-phenylenediamine, 100 mL of chloroform and 100 mL of petroleum ether were added to a crystallizer, and the mixture was heated to 60° C. with stirring to dissolve all the solids. The mixture was then cooled at a rate of 10° C. / h, 1 g of o-phenylenediamine seed crystals were added at 30° C., and the crystals were then grown at a constant temperature for 30 minutes. The temperature was then further cooled at a rate of 10° C. / h until the temperature dropped to 5° C., and the crystals were aged at a constant temperature for 30 minutes. The slurry was then filtered to obtain a filter cake. The o-phenylenediamine filter cake was washed with 50 mL of a chloroform-petroleum ether mixed solvent (25 mL of chloroform and 25 mL of petroleum ether), and the filter cake was dried after filtering again to obtain an o-phenylenediamine block crystal product with a purity of 99.999%.

[0038] Example 7.

[0039] 100 g of crude o-phenylenediamine, 500 mL of 1,2-dichloroethane and 500 mL of petroleum ether were added to a crystallizer, stirred and heated to 50°C to dissolve all the solids, then cooled at a rate of 1°C / h, 1 g of o-phenylenediamine seed crystals were added at 30°C, and then the crystals were grown at a constant temperature for 60 minutes, and then the temperature was continued to be reduced at a rate of 15°C / h. After the temperature dropped to 5°C, the crystals were aged at a constant temperature for 30 minutes, and then the slurry was filtered to obtain a filter cake, and the o-phenylenediamine filter cake was washed with 300 mL of 1,2-dichloroethane-petroleum ether mixed solvent (50 mL of 1,2-dichloroethane and 250 mL of petroleum ether), and the filter cake was dried after filtering again to obtain an o-phenylenediamine block crystal product with a purity of 99.997%.

[0040] As one of the important indicators of crystal product quality, crystal morphology not only affects product properties such as fluidity and bulk density, but also affects its downstream production process and terminal storage and transportation. The product obtained by the present invention is a transparent block crystal, which has the advantages of good fluidity, high bulk density, and concentrated particle size distribution compared to commercially available sliced ​​products; in the downstream use process, block crystals are easier to store and transport; in addition, compared to sliced ​​products, granular crystals are not easy to break, and the dust environment caused by product breakage can be effectively avoided during use.

[0041] The technical solutions disclosed and proposed by the present invention can be realized by those skilled in the art by referring to the contents of this article and appropriately changing the conditions, routes and other links. Although the methods and preparation techniques of the present invention have been described through preferred embodiments, relevant technicians can obviously modify or re-combine the methods and technical routes described herein without departing from the content, spirit and scope of the present invention to realize the final preparation technology. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the spirit, scope and content of the present invention.

Claims

1. A method for crystallizing and refining high-purity bulk o-phenylenediamine, characterized in that: The crude o-phenylenediamine, good solvent and anti-solvent are added into a crystallizer, stirred and heated to 50-70°C to dissolve all the solids, then the temperature is lowered, o-phenylenediamine seed crystals are added at 30-45°C, then the crystals are grown at a constant temperature for 30-60 minutes, the temperature is further lowered to 5-20°C, the crystals are aged at a constant temperature for 30-60 minutes, and then the crystal slurry is filtered to obtain a filter cake; the filter cake is rinsed with a mixed solvent prepared with a good solvent and an anti-solvent, and the filter cake is dried after filtering again to obtain a high-purity block o-phenylenediamine crystal product.

2. The method according to claim 1, characterized in that The good solvent is selected from one of methanol, ethanol, isopropanol, n-propanol, n-butanol, acetonitrile, ethyl acetate, tetrahydrofuran, dichloromethane, chloroform, tetrachloromethane and 1,2-dichloroethane.

3. The method according to claim 1, characterized in that The anti-solvent is selected from one of water, n-hexane, cyclohexane, n-heptane and petroleum ether.

4. The method according to claim 1, characterized in that The mass volume ratio of crude o-phenylenediamine, good solvent and anti-solvent is 1 g: 0.5-5 mL: 0.5-5 mL.

5. The method according to claim 1, characterized in that The amount of o-phenylenediamine seed crystals added is 0.01% to 2% of the initial o-phenylenediamine crude quality.

6. The method according to claim 1, characterized in that The cooling rate is 1-20°C / h.

7. The method according to claim 1, characterized in that The mixed solvent is a mixed solvent of a good solvent and an anti-solvent, and the volume ratio of the good solvent to the anti-solvent is 1:1-5.

8. The method according to claim 1, characterized in that The mass volume ratio of crude o-phenylenediamine and mixed solvent is 1g:0.1-3mL.

Images