Preparation method of 4, 5-diaminobenzene-1, 3 disulfonic acid

Abstract

The invention relates to a preparation method of 4, 5-diaminobenzene-1, 3 disulfonic acid, which comprises the following steps: a, adding concentrated sulfuric acid into a container provided with a thermometer and a stirring device, controlling the temperature and slowly adding o-phenylenediamine to obtain a sulfuric acid solution of o-phenylenediamine; b, slowly dropwise adding fuming sulfuric acid into the sulfuric acid solution of o-phenylenediamine in the step a, carrying out heat preservation reaction, and cooling; c, pouring the product in the step b into an ice-water mixture, adding activated carbon, stirring, and filtering to remove the activated carbon to obtain a diluent; d, carrying out reduced pressure distillation, concentration and cooling on the diluent; e, cooling, stirring, filtering and taking a solid to obtain a 4, 5-diaminobenzene-1, 3 disulfonic acid crude product; and f, adding the crude product into an organic solvent, pulping, washing acid, stirring, filtering to obtain a solid, and drying to obtain the 4, 5-diaminobenzene-1, 3-disulfonic acid. The method has the advantages of mild reaction conditions, normal pressure reaction, high yield, easily available raw materials and simple process, can be directly obtained by one-step sulfonation, and is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to a method for preparing 4,5-diaminobenzene-1,3-disulfonic acid, belonging to the field of organic synthesis technology. Background Technology

[0002] 4,5-Diaminophenyl-1,3-disulfonic acid is an important chemical raw material, belonging to the aromatic disulfonic acid derivatives. Its amino and sulfonic acid groups in its molecular structure endow it with high reactivity, making it widely used in the dye industry as an intermediate for reactive and acid dyes, especially in the synthesis of anthraquinone dyes, improving color fastness and water solubility. Currently, the global dye market is growing year by year, with increasing demand for environmentally friendly dyes driving the demand for high-purity intermediates. 4,5-Diaminophenyl-1,3-disulfonic acid participates in the preparation of high-performance polymers such as polyamides and polyimides, improving the heat resistance and mechanical strength of materials; it is also an intermediate used in the synthesis of antitumor drugs. It has the following structural formula:

[0003] Existing technologies are mainly synthesized through the following pathways, but they have significant drawbacks: The nitration-reduction method uses benzenedisulfonic acid as a raw material, which is nitrated with mixed acids to produce dinitrobenzenedisulfonic acid, and then reduced to a diamino product. The main problems include: the nitration step requires strong acid, leading to severe equipment corrosion; poor regional selectivity and low product purity; and the use of iron powder or sodium sulfide in the reduction stage, generating large amounts of wastewater containing heavy metals. Another method is the amino protection method, which introduces a protecting group before sulfonation, but this is cumbersome, with a yield of only 50-60%, and high costs. Furthermore, obtaining sulfonates of the product is difficult, as it is challenging to directly obtain high-purity 4,5-diaminophenyl-1,3-disulfonic acid. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a method for preparing 4,5-diaminobenzene-1,3-disulfonic acid. The reaction conditions are mild, the reaction is carried out at atmospheric pressure, the yield is high, the raw materials are readily available, the process is relatively simple, and it can be obtained directly by one-step sulfonation, making it suitable for industrial production.

[0005] The technical solution adopted by this invention to solve its technical problem is: A method for preparing 4,5-diaminobenzene-1,3-disulfonic acid, the method comprising the following steps: a. Add concentrated sulfuric acid to a container equipped with a thermometer and a stirring device, control the temperature and slowly add o-phenylenediamine to obtain a sulfuric acid solution of o-phenylenediamine; b. Slowly add fuming sulfuric acid dropwise to the o-phenylenediamine sulfuric acid solution from step a. After the addition is complete, immediately carry out the reaction at a constant temperature for 6-20 hours until the o-phenylenediamine content in the reaction system is 2-3%. After the reaction is completed, cool to 50-60℃. c. Pour the product from step b into an ice-water mixture, maintain the temperature at 15-20°C, add activated carbon, stir for 0.5-1 h, filter to remove the activated carbon, and obtain a diluted solution. d. Concentrate the diluted solution from step c by vacuum distillation; e. After cooling the concentrated solution from step d to 10-20℃, stir for 0.5h, filter to obtain the solid, and get crude 4,5-diaminobenzene-1,3-disulfonic acid. f. Add a measured amount of organic solvent to the crude product obtained in step e for pulping and acid washing. After stirring for 0.5 h, filter to obtain the solid, and dry to obtain 4,5-diaminobenzene-1,3-disulfonic acid.

[0006] In the above-mentioned method for preparing 4,5-diaminobenzene-1,3-disulfonic acid, in steps a and b, the concentration of concentrated sulfuric acid is 95-99%, the concentration of fuming sulfuric acid is 20-50%, and the molar ratio of o-phenylenediamine to sulfur trioxide in the system is 1:2-5; after the fuming sulfuric acid is added, the concentration of fuming sulfuric acid after mixing concentrated sulfuric acid and fuming sulfuric acid in the system is 8.89%-20%.

[0007] In the above method for preparing 4,5-diaminobenzene-1,3-disulfonic acid, in step a, the feeding time of o-phenylenediamine is 0.5-1 h, and the feeding temperature is below 70°C.

[0008] In the above method for preparing 4,5-diaminobenzene-1,3-disulfonic acid, the reaction temperature in step b is 70-100℃.

[0009] In the above method for preparing 4,5-diaminobenzene-1,3-disulfonic acid, the acid concentration of the diluent in step c is 15-30%.

[0010] In the above method for preparing 4,5-diaminobenzene-1,3-disulfonic acid, in step c, the initial feed amount of o-phenylenediamine to the mass ratio of activated carbon is 1:4-12.

[0011] In the above method for preparing 4,5-diaminobenzene-1,3-disulfonic acid, in step d, the distillation is stopped after the sulfuric acid concentration is concentrated under reduced pressure to 35-40%.

[0012] In the above method for preparing 4,5-diaminobenzene-1,3-disulfonic acid, the organic solvent in step f is acetonitrile or dioxane.

[0013] In the above method for preparing 4,5-diaminobenzene-1,3-disulfonic acid, in step f, the ratio of crude product to organic solvent (m:v) is 1:2-4.

[0014] The beneficial effects of this invention are: the preparation method of this invention uses o-phenylenediamine as raw material to directly sulfonate and synthesize 4,5-diaminobenzene-1,3-disulfonic acid. The reaction conditions are mild, the yield is high, reaching more than 73%, the product purity is high, and it is more than 99.3%. The raw materials are readily available, the process is relatively simple, and it is suitable for industrial production. Attached Figure Description

[0015] Figure 1 The high-performance liquid chromatogram of the product obtained in Example 1; Figure 2 The high-performance liquid chromatogram of the product obtained in Example 2; Figure 3 The high-performance liquid chromatogram of the product obtained in Example 3; Figure 4 The high-performance liquid chromatogram of the product obtained in Example 4; Figure 5 The image shows the high-performance liquid chromatogram of the product obtained in Example 5. Detailed Implementation

[0016] This invention discloses a method for preparing 4,5-diaminobenzene-1,3-disulfonic acid, the method comprising the following steps: a. Add concentrated sulfuric acid to a container equipped with a thermometer and a stirring device, control the temperature and slowly add o-phenylenediamine to obtain a sulfuric acid solution of o-phenylenediamine; b. Slowly add fuming sulfuric acid dropwise to the o-phenylenediamine sulfuric acid solution from step a. After the addition is complete, immediately carry out the reaction at a constant temperature for 6-20 hours until the o-phenylenediamine content in the reaction system is 2-3%. After the reaction is completed, cool to 50-60℃. c. Pour the product from step b into an ice-water mixture, maintain the temperature at 15-20°C, add activated carbon, stir for 0.5-1 h, filter to remove the activated carbon, and obtain a diluted solution. d. Concentrate the diluted solution from step c by vacuum distillation; e. After cooling the concentrated solution from step d to 10-20℃, stir for 0.5h, filter to obtain the solid, and get crude 4,5-diaminobenzene-1,3-disulfonic acid. f. Add a measured amount of organic solvent to the crude product obtained in step e for pulping and acid washing. After stirring for 0.5 h, filter to obtain the solid, and dry to obtain 4,5-diaminobenzene-1,3-disulfonic acid.

[0017] In steps a and b, the concentration of concentrated sulfuric acid is 95-99%, the concentration of fuming sulfuric acid is 20-50%, and the molar ratio of o-phenylenediamine to sulfur trioxide in the system is 1:2-5. After the fuming sulfuric acid is added, the concentration of fuming sulfuric acid after mixing the concentrated sulfuric acid and fuming sulfuric acid in the system is 8.89%-20%. Controlling the concentration of fuming sulfuric acid after mixing the concentrated sulfuric acid and fuming sulfuric acid in the system to 8.89%-20% is crucial. If the sulfuric acid concentration is too low, a large amount of o-phenylenediamine will remain, and more 3,4-diaminobenzenesulfonic acid will be generated, resulting in a longer reaction time and making it difficult to obtain a product with a purity of over 99%, requiring a purification process. However, adding a purification process will affect the product yield. If the sulfuric acid concentration is too high, the reaction will be too fast, generating more impurities, and purification is still required.

[0018] In step c, the acid concentration of the diluent is 15-30%. Sulfone impurities are formed during the sulfonation reaction. These impurities are soluble in strong acids, but at this acid concentration, they are more likely to precipitate and are easier to remove.

[0019] In step c, the mass ratio of o-phenylenediamine to activated carbon is 1:4-12. Using activated carbon for adsorption can also remove impurities and ensure the content of the final product. When the amount of activated carbon is too small, the impurities are not fully adsorbed, which affects the purity of the product. When the amount of activated carbon is too large, it will adsorb the product and the filtration speed will be slow, reducing the product yield.

[0020] In step d, distillation is stopped after the sulfuric acid concentration is concentrated to 35-40% under reduced pressure. If the concentration is too low, less crude product will precipitate; if the concentration is too high, impurities will easily precipitate, and the crude product will be too sticky and difficult to process.

[0021] In step f, the organic solvent is acetonitrile or dioxane. The product has high solubility in water, resulting in significant residual sulfuric acid that is difficult to remove. Adding an organic solvent to the system to pulp the crude product removes residual sulfuric acid. Therefore, a solvent miscible with acid and water needs to be selected. However, commonly used laboratory alcohols have high solubility in the product, leading to significant product loss after pulping and reduced yield. Furthermore, to facilitate drying, the boiling point of the organic solvent should not be too high. Therefore, after experimental screening, acetonitrile and dioxane were ultimately chosen to ensure product purity and yield.

[0022] The present invention will be further described below with reference to the embodiments. Example 1

[0023] The preparation method of 4,5-diaminobenzene-1,3-disulfonic acid includes the following steps: (1) Add 67.51g of 98% sulfuric acid to a dry 500ml four-necked flask, slowly add 21.83g of o-phenylenediamine, control the temperature at 65℃, and add the material for 37min to dissolve the o-phenylenediamine in the sulfuric acid.

[0024] (2) After adding o-phenylenediamine, slowly add 292.53 g of 26.66% fuming sulfuric acid to the o-phenylenediamine sulfuric acid solution over 45 min, and keep the temperature at 80°C. After the addition is complete, keep the temperature at 90°C for 8 h, take a sample to measure the endpoint, and continue until the o-phenylenediamine content in the reaction system is less than 3%. After the reaction is complete, cool to 53°C. (3) Add 750g of ice-water mixture to a 1000ml beaker, slowly pour the material from the flask in step (2) into the beaker, maintain 15℃, add 5g of activated carbon, stir for 0.5h, filter to remove activated carbon, and obtain diluted solution; (4) Transfer the diluted solution from step (3) into a 1000ml four-necked flask, equipped with a stirrer and thermometer, and perform vacuum distillation to concentrate it. When the system temperature is 70℃ and the ambient temperature is 55℃, cool it down. (5) After cooling the concentrated solution in step (4) to 15°C, stir for 0.5 h, filter to obtain the solid, and obtain crude 4,5-diaminobenzene-1,3-disulfonic acid. (6) Add the crude product obtained in step (5) to acetonitrile. The ratio of crude product to acetonitrile (m:v) is 1:3. After slurrying and acid washing, the mixture is stirred for 0.5 h and then filtered to obtain solid 4,5-diaminobenzene-1,3-disulfonic acid. After drying, the yield is 77% and the purity is 99.748%.

[0025] Figure 1 The high-performance liquid chromatogram of the obtained product is shown. The peak at retention time of 28.005 min is the product peak, with a product content of 99.748%. The peak at 5.896 min is the impurity 3,4-diaminobenzenesulfonic acid, with a content of 0.153%. This indicates that the product prepared by the method of the present invention has high purity. Example 2

[0026] The preparation method of 4,5-diaminobenzene-1,3-disulfonic acid includes the following steps: (1) Add 67.51g of 98% sulfuric acid into a dry 500ml four-necked flask, slowly add 21.83g of o-phenylenediamine, control the temperature at 65℃, and add the material for about 40 minutes to dissolve the o-phenylenediamine in the sulfuric acid.

[0027] (2) After adding o-phenylenediamine, slowly add 202.52 g of 26.66% fuming sulfuric acid to the o-phenylenediamine sulfuric acid solution over 40 min, and keep the temperature at 85°C. After the addition is complete, keep the temperature at 100°C for 13 h, take a sample to measure the endpoint, and continue until the o-phenylenediamine content in the reaction system is less than 2%. After the reaction is complete, cool to 55°C. (3) Add 600g of ice-water mixture to a 1000ml beaker, slowly pour the material from the flask in step (2) into the beaker, maintain 15℃, add 2g of activated carbon, stir for 0.5h, filter to remove activated carbon, and obtain diluted solution; (4) Transfer the diluted solution from step (3) into a 1000ml four-necked flask, equipped with a stirrer and thermometer, and perform vacuum distillation to concentrate it. When the system temperature is 62℃ and the ambient temperature is 52℃, cool it down. (5) After cooling the concentrate from step (4) to 15°C, stir for 0.5 h. Filter to obtain crude 4,5-diaminobenzene-1,3-disulfonic acid; (6) Add the crude product obtained in step (5) to dioxane, with the ratio of crude product to dioxane (m:v) = 1:2 for pulping and acid washing. After stirring for 0.5 h, filter to obtain solid, and obtain 4,5-diaminobenzene-1,3-disulfonic acid. After drying, its yield is 75% and its purity is 99.60%.

[0028] Figure 2 The high-performance liquid chromatogram of the obtained product is shown. The peak at retention time of 27.266 min is the product peak, with a product content of 99.60%. The peak at 5.840 min is the impurity 3,4-diaminobenzenesulfonic acid, with a content of 0.271%. This indicates that the product prepared by the method of the present invention has high purity. Example 3

[0029] The preparation method of 4,5-diaminobenzene-1,3-disulfonic acid includes the following steps: (1) Put 96.44g of 95% sulfuric acid into a dry 500ml four-necked flask, slowly add 21.83g of o-phenylenediamine into it, control the temperature at 68℃, and add the material for about 34 minutes to dissolve the o-phenylenediamine in the concentrated sulfuric acid.

[0030] (2) After adding o-phenylenediamine, slowly add 173.59 g of 40% fuming sulfuric acid to the o-phenylenediamine sulfuric acid solution, which takes about 45 min to complete, and keep the temperature at 85℃; after the addition is complete, keep the temperature at 90℃ for 10.5 h, take a sample to measure the endpoint, until the o-phenylenediamine content in the reaction system is less than 2%; after the reaction is completed, cool to 50℃; (3) Add 500g of ice-water mixture to a 1000ml beaker, slowly pour the material from the flask in step (2) into the beaker, maintain 15℃, add 3g of activated carbon, stir for 0.5h, filter to remove activated carbon, and obtain diluted solution; (4) Transfer the diluted solution from step (3) into a 1000ml four-necked flask, equipped with a stirrer and thermometer, and perform vacuum distillation to concentrate it. When the system temperature is 65℃ and the ambient temperature is 52℃, cool it down. (5) After cooling the concentrate from step (4) to 15°C, stir for 0.5 h. Filter to obtain crude 4,5-diaminobenzene-1,3-disulfonic acid; (6) Add the crude product obtained in step (5) to acetonitrile. The crude product:acetonitrile (m:v) = 1:3.5 is pulped and washed with acid. After stirring for 0.5 h, the solid is filtered to obtain 4,5-diaminobenzene-1,3-disulfonic acid. After drying, its yield is 75% and its purity is 99.30%.

[0031] Figure 3 The high-performance liquid chromatogram of the obtained product shows that the peak at a retention time of 27.860 min is the product peak, with a product content of 99.30%, and the peak at 5.862 min is the impurity 3,4-diaminobenzenesulfonic acid, with a content of 0.34%. This indicates that the product prepared by the method of the present invention has high purity. Example 4

[0032] The preparation method of 4,5-diaminobenzene-1,3-disulfonic acid includes the following steps: (1) Put 152.32g of 95% sulfuric acid into a dry 500ml four-necked flask, slowly add 21.83g of o-phenylenediamine into it, control the temperature at 67℃, and add the material for about 42 minutes to dissolve the o-phenylenediamine in the sulfuric acid.

[0033] (2) After adding o-phenylenediamine, slowly add 147.70 g of 50% fuming sulfuric acid to the o-phenylenediamine sulfuric acid solution, which takes about 45 min to complete, and keep the temperature at 85℃; after the addition is complete, keep the temperature at 100℃ for 16 h, take a sample to measure the endpoint, until the o-phenylenediamine content in the reaction system is less than 2%; after the reaction is completed, cool to 50℃; (3) Add 600g of ice-water mixture to a 1000ml beaker, slowly pour the material from the flask in step (2) into the beaker, maintain 15℃, add 3.5g of activated carbon, stir for 0.5h, filter to remove activated carbon, and obtain diluted solution; (4) Transfer the diluted solution from step (3) into a 1000ml four-necked flask, equipped with a stirrer and thermometer, and perform vacuum distillation to concentrate it. When the system temperature is 63℃ and the ambient temperature is 50℃, cool it down. (5) After cooling the concentrate from step (4) to 15°C, stir for 0.5 h. Filter to obtain crude 4,5-diaminobenzene-1,3-disulfonic acid; (6) Add the crude product obtained in step (5) to dioxane, the ratio of crude product to dioxane = (m:v) = 1:2.5, and perform pulping and acid washing. After stirring for 0.5 h, filter to obtain solid, and obtain 4,5-diaminobenzene-1,3 disulfonic acid. After drying, its yield is 73% and its purity is 99.791%.

[0034] Figure 4 The high-performance liquid chromatogram of the obtained product shows that the peak at retention time of 27.986 min is the product peak, with a product content of 99.791%, and the peak at 5.874 min is the impurity 3,4-diaminobenzenesulfonic acid, with a content of 0.181%. This indicates that the product prepared by the method of the present invention has high purity. Example 5

[0035] The preparation method of 4,5-diaminobenzene-1,3-disulfonic acid includes the following steps: (1) Put 138.46g of 96% sulfuric acid into a dry 500ml four-necked flask, slowly add 21.83g of o-phenylenediamine into it, control the temperature at 65℃, and add the material for about 38 minutes to dissolve the o-phenylenediamine in the sulfuric acid.

[0036] (2) After adding o-phenylenediamine, slowly add 261.54 g of 40% fuming sulfuric acid to the o-phenylenediamine sulfuric acid solution, which takes about 45 min to complete, and keep the temperature at 80℃; after the addition is complete, keep the temperature at 80℃ for 8 h, take a sample to measure the endpoint, until the o-phenylenediamine content in the reaction system is less than 2%; after the reaction is completed, cool to 51℃; (3) Add 800g of ice-water mixture to a 1000ml beaker, slowly pour the material from the flask in step (2) into the beaker, maintain 15℃, add 4g of activated carbon, stir for 0.5h, filter to remove activated carbon, and obtain diluted solution; (4) Transfer the diluted solution from step (3) into a 2000ml four-necked flask, equipped with a stirrer and thermometer, and perform vacuum distillation to concentrate it. When the system temperature is 70℃ and the ambient temperature is 56℃, cool it down. (5) After cooling the concentrate from step (4) to 15°C, stir for 0.5 h. Filter to obtain crude 4,5-diaminobenzene-1,3-disulfonic acid; (6) Add the crude product obtained in step (5) to dioxane, the ratio of crude product to dioxane = (m:v) = 1:2.5, and perform pulping and acid washing. After stirring for 0.5 h, filter to obtain solid, and obtain 4,5-diaminobenzene-1,3 disulfonic acid. After drying, its yield is 74% and its purity is 99.678%.

[0037] Figure 5 The high-performance liquid chromatogram of the obtained product is shown. The peak at retention time of 28.320 min is the product peak, with a product content of 99.678%. The peak at 5.934 min is the impurity 3,4-diaminobenzenesulfonic acid, with a content of 0.233%. This indicates that the product prepared by the method of the present invention has high purity.

Claims

1. A method for preparing 4,5-diaminobenzene-1,3-disulfonic acid, characterized in that: The preparation method includes the following steps: a. Add concentrated sulfuric acid to a container equipped with a thermometer and a stirring device, control the temperature and slowly add o-phenylenediamine to obtain a sulfuric acid solution of o-phenylenediamine; b. Slowly add fuming sulfuric acid dropwise to the o-phenylenediamine sulfuric acid solution from step a. After the addition is complete, immediately carry out the reaction at a constant temperature for 6-20 hours until the o-phenylenediamine content in the reaction system is 2-3%. After the reaction is completed, cool to 50-60℃. c. Pour the product from step b into an ice-water mixture, maintain the temperature at 15-20°C, add activated carbon, stir for 0.5-1 h, filter to remove the activated carbon, and obtain a diluted solution. d. Concentrate the diluted solution from step c by vacuum distillation; e. After cooling the concentrated solution from step d to 10-20℃, stir for 0.5h, filter to obtain the solid, and get crude 4,5-diaminobenzene-1,3-disulfonic acid. f. Add a measured amount of organic solvent to the crude product obtained in step e for pulping and acid washing. After stirring for 0.5 h, filter to obtain the solid, and dry to obtain 4,5-diaminobenzene-1,3-disulfonic acid.

2. The method for preparing 4,5-diaminobenzene-1,3-disulfonic acid according to claim 1, characterized in that: In steps a and b, the concentration of concentrated sulfuric acid is 95-99%, the concentration of fuming sulfuric acid is 20-50%, and the molar ratio of o-phenylenediamine to sulfur trioxide in the system is 1:2-5. After the fuming sulfuric acid is added, the concentration of fuming sulfuric acid in the system after mixing concentrated sulfuric acid and fuming sulfuric acid is 8.89%-20%.

3. The method for preparing 4,5-diaminobenzene-1,3-disulfonic acid according to claim 1, characterized in that: In step a, the feeding time of o-phenylenediamine is 0.5-1 hour, and the feeding temperature is below 70°C.

4. The method for preparing 4,5-diaminobenzene-1,3-disulfonic acid according to claim 1, characterized in that: In step b, the reaction temperature is 70-100℃.

5. The method for preparing 4,5-diaminobenzene-1,3-disulfonic acid according to claim 1, characterized in that: In step c, the acid concentration of the diluent is 15-30%.

6. The method for preparing 4,5-diaminobenzene-1,3-disulfonic acid according to claim 1, characterized in that: In step c, the initial feed amount of o-phenylenediamine to activated carbon has a mass ratio of 1:4-12.

7. The method for preparing 4,5-diaminobenzene-1,3-disulfonic acid according to claim 1, characterized in that, In step d, the sulfuric acid is concentrated under reduced pressure until the concentration reaches 35-40%, and then the distillation is stopped.

8. The method for preparing 4,5-diaminobenzene-1,3-disulfonic acid according to claim 1, characterized in that, In step f, the organic solvent is acetonitrile or dioxane.

9. The method for preparing 4,5-diaminobenzene-1,3-disulfonic acid according to claim 1, characterized in that, In step f, the mass-to-volume ratio of the crude product to the organic solvent is 1:2-4.

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