Preparation method of 2, 5-disulfonic aniline sodium salt

Abstract

The invention relates to a preparation method of 2, 5-disulfonic acid aniline sodium salt, which comprises the following steps: heating and melting o-chloronitrobenzene in a reaction device, and dropwise adding sulfur trioxide; heating and sulfonating twice, and keeping the temperature to the sulfonation end point; dropwise adding the sulfonated product into water for dilution, adding activated carbon for decoloration, and filtering to obtain sulfonated diluent; adding alkali liquor into the sulfonation diluent, adjusting the pH value of the system, then adding sulfite, and heating, refluxing, replacing and sulfonating to the end point; adjusting the system to be neutral with acid; oxidation pretreatment: dropwise adding an oxidant into a neutral reaction system, and carrying out heat preservation reaction to an oxidation end point; catalytic hydrogenation: adding a noble metal catalyst into a reaction system, introducing hydrogen, and carrying out catalytic hydrogenation; and adding inorganic salt for salting out, cooling, preserving heat, growing crystals, separating out, filtering and drying to obtain a finished product. Through an integrated route of SO3 sulfonation, oxidation pretreatment and catalytic hydrogenation, one-pot method continuous operation can be performed under mild conditions, the product purity is greater than or equal to 99%, the yield is greater than or equal to 90%, and the catalyst can be stably and mechanically applied for more than 20 times.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of 2,5-bis-sulfonic acid aniline sodium salt and belongs to the technical field of preparation of fine chemical intermediates. BACKGROUND

[0002] 2,5-bis-sulfonic acid aniline sodium salt is an important dye intermediate, which has a diazotizable amino group and a water-soluble sulfonic acid group. It is mainly used for synthesizing acid dyes, direct dyes and reactive dyes and is applied to dyeing of wool and cotton fabrics. Meanwhile, it is also a key raw material for fluorescent whitening agents and organic pigments and is widely used in the textile, plastic and ink industries. At present, the industrial production of 2,5-bis-sulfonic acid aniline sodium salt mainly adopts a process route in which m-aminobenzenesulfonic acid is used as a raw material, is sulfonated by fuming sulfuric acid and is salted out by sodium chloride. The process has high cost of m-aminobenzenesulfonic acid, and isomer byproducts (such as 2,4-disulfonic acid) are easily generated in the process, which are extremely difficult to separate, affect the purity of the product, and cause a large amount of high-acid wastewater to be generated by fuming sulfuric acid, thus having high treatment cost.

[0003] O-chloronitrobenzene is gradually becoming the primary choice for replacing m-aminobenzenesulfonic acid to prepare 2,5-bis-sulfonic acid aniline sodium salt due to its low cost. A preparation method of 2,5-bis-sulfonic acid aniline sodium salt is disclosed in Polish Patent PL173982B1, which uses o-chloronitrobenzene as a raw material and fuming sulfuric acid as a sulfonating agent in the sulfonation reaction, thus causing a large amount of high-COD acid wastewater to be generated, which significantly burdens the environment. In addition, the Bechamp reduction method is used in the nitro reduction step in the process, and an excess of iron powder is consumed as a reducing agent. After the reaction, the unreacted iron, generated iron oxides and other inactivated impurities are mixed together to form solid residues that are difficult to separate and cannot be recycled. This not only leads to a large waste of iron resources, but also further aggravates the pollution problem of solid waste. Overall, the synthesis route has obvious deficiencies in resource utilization and environmental friendliness. SUMMARY

[0004] The application provides a preparation method of 2,5-bis-sulfonic acid aniline sodium salt to overcome the drawbacks of the prior art, uses o-chloronitrobenzene as a raw material, and realizes one-pot continuous operation under mild conditions through an integrated route of SO3 sulfonation-oxidation pretreatment-catalytic hydrogenation, so that the product purity is greater than or equal to 99%, the yield is greater than or equal to 90%, and the catalyst can be stably used for more than 20 times.

[0005] The technical scheme adopted by the application to solve the technical problems is as follows: A preparation method of 2,5-bis-sulfonic acid aniline sodium salt, the preparation method comprising the following steps: (1) One-step sulfonation: o-chloronitrobenzene is added to a reaction device, heated and melted, and then sulfur trioxide is slowly added dropwise under temperature control; after the dropwise addition is completed, the temperature is first raised to a first sulfonation temperature for a holding reaction, and then raised to a second sulfonation temperature, and the holding reaction is continued until the sulfonation endpoint; then, the obtained sulfonated product is slowly added dropwise into a predetermined amount of water for dilution, activated carbon is added for decolorization, and filtration is performed to obtain a sulfonated dilution liquid; (2) Displacement sulfonation: lye is added to the sulfonated dilution liquid, the pH of the system is adjusted to 9-10, a predetermined amount of sulfite is added, and displacement sulfonation is performed under heating and reflux until the endpoint; after the reaction is completed, the system is adjusted to neutral with acid; (3) Oxidation pretreatment: a predetermined amount of oxidizing agent is slowly added dropwise into the above neutral reaction system, and the holding reaction is continued until the oxidation endpoint; (4) Catalytic hydrogenation: a predetermined amount of noble metal catalyst is added to the reaction system after the oxidation pretreatment, hydrogen is replaced after hydrogenation, and then hydrogen is introduced under a set pressure and temperature condition to perform catalytic hydrogenation until the reduction endpoint; (5) Salting-out and post-treatment: after the reduction reaction is completed, inorganic salt is added to the reaction system for salting-out, and then the temperature is lowered and held for crystal growth, so that the product is fully analyzed and precipitated; after filtration and drying, the 2,5-disulfonic acid aniline sodium salt product is obtained.

[0006] In the above method for preparing 2,5-disulfonic acid aniline sodium salt, in step (3), the oxidizing agent is hydrogen peroxide or peroxoacetic acid In the above method for preparing 2,5-disulfonic acid aniline sodium salt, in step (3), the temperature of the oxidation pretreatment reaction is 100-105°C, and the reaction time is 1-2 h; the molar amount ratio of the oxidizing agent to the sulfite in step (2) is (1-1.1):1.

[0007] In the above method for preparing 2,5-disulfonic acid aniline sodium salt, in step (1), the molar feeding ratio of o-chloronitrobenzene, sulfur trioxide, and water is 1:(1.0-1.5):(30-40).

[0008] In the above method for preparing 2,5-disulfonic acid aniline sodium salt, in step (1), the melting temperature of o-chloronitrobenzene is 40-50°C; the dropwise addition temperature of sulfur trioxide is 40-60°C; the first sulfonation temperature is 70-80°C, and the holding reaction time is 3-4 h; the second sulfonation temperature is 100-105°C, and the holding reaction time is 2-3 h; the temperature for diluting the sulfonated product with water is lower than 100°C; the amount of activated carbon added is 2-5% of the mass of o-chloronitrobenzene; and the decolorization time is 0.5-1 h.

[0009] The preparation method of the above-mentioned 2,5-bis-sulfonic acid aniline sodium salt, in the step (2), the base is one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, which can be added in solid or solution form; the sulfite is one or more of sodium sulfite, potassium sulfite; the molar feeding ratio of the sulfite to o-chloronitrobenzene is (2-3) : 1; the acid used for neutralization is concentrated hydrochloric acid or sulfuric acid.

[0010] The preparation method of the above-mentioned 2,5-bis-sulfonic acid aniline sodium salt, in the step (4), the noble metal catalyst is palladium-carbon or platinum-carbon; the mass ratio of o-chloronitrobenzene to noble metal in the noble metal catalyst is (1500-2000) : 1; the hydrogenation reaction temperature is 70-80 DEG C, the hydrogen pressure is 0.5-1.0 MPa, and the reaction time is 2-3 h. Catalytic hydrogenation makes the nitro group be completely reduced to amino group.

[0011] The preparation method of the above-mentioned 2,5-bis-sulfonic acid aniline sodium salt, in the step (5), the inorganic salt is sodium chloride or sodium sulfate; the molar feeding ratio of the metal ion in the inorganic salt to o-chloronitrobenzene is (5-6) : 1; the salting-out operation temperature is 35-40 DEG C.

[0012] The beneficial effects of the present application are: 1. In the preparation method, after the sulfonation reaction, the "oxidation pretreatment" step is added to remove the residual sulfite ions in the reaction system, purify the reaction system, solve the problem of low-valence sulfur impurities poisoning the noble metal catalyst, enable the noble metal catalyst to be reused for more than 20 times, and greatly reduce the use cost of the catalyst.

[0013] 2. The combination process of "liquid SO3 sulfonation" and "catalytic hydrogenation reduction" eliminates the high-COD acid-containing wastewater from traditional fuming sulfuric acid sulfonation and the iron-containing sludge from iron powder reduction from the source, realizes substantial reduction of pollutants and clean process.

[0014] The preparation method has mild reaction conditions, realizes "one-pot" continuous operation, and does not need to separate the intermediates, which simplifies the process, reduces energy consumption, and guarantees the product purity ≥ 99% and the yield ≥ 90%. DETAILED DESCRIPTION

[0015] In the preparation method, after the sulfonation is completed, the oxidation pretreatment step is added to remove the residual sulfite and other low-valence sulfur ions in the system by using an oxidizing agent, so as to avoid the influence of low-valence sulfur substances on the subsequent noble metal hydrogenation catalytic effect, and enable the catalyst to be reused for 20 times or more.

[0016] In the one-step sulfonation process, sulfur trioxide is selected as the sulfonating agent. In the one-step sulfonation process, the temperature is first raised to a first sulfonation temperature of 70-80 DEG C for a heat preservation reaction, and then continuously raised to a second sulfonation temperature of 100-105 DEG C for a heat preservation reaction until the sulfonation endpoint. Sulfur trioxide is directly used as a sulfonating agent, and two-step temperature rising overcomes the defect that SO3 reaction is too violent. The low-temperature reaction gradually releases and effectively removes the reaction heat, inhibits side reactions, the high-temperature reaction ensures that the reaction can be quickly and completely carried out, but is controlled within the limit that will not cause significant side reactions, thereby fully exerting the inherent advantages of high atomic economy, no waste acid generation (conventional fuming sulfuric acid uses concentrated sulfuric acid as a solvent, resulting in a large amount of sulfuric acid in waste water), and excellent product quality.

[0017] The present application utilizes catalytic hydrogenation reduction to avoid the generation of iron-containing sludge caused by traditional reduction using iron powder. In the catalytic hydrogenation process, the mass ratio of o-chloronitrobenzene to noble metal in the noble metal catalyst is controlled to be (1500-2000):1; the hydrogenation reaction temperature is 70-80 DEG C, the hydrogen pressure is 0.5-1.0 MPa, and the reaction time is 2-3 h.

[0018] In the catalytic hydrogenation of nitrobenzene compounds in a chlorine ion-containing system, the reaction temperature and hydrogen pressure are key process parameters that need to be optimized in coordination. The selection thereof can ensure high reaction activity, achieve extremely high selectivity, and significantly inhibit catalyst poisoning caused by the presence of chlorine ions (chlorine ions have much weaker poisoning effect on the catalyst than lower-valence sulfur substances, and the poisoning effect can be alleviated by reaction conditions).

[0019] The synergistic effect between the mild temperature (70-80 DEG C) and the medium-low pressure (0.5-1.0 MPa). This "mild-medium-low pressure" operation strategy, in combination with a specific substrate / catalyst mass ratio ((1500-2000):1), creates an optimal reaction microenvironment: The rapid hydrogen mass transfer provided by the pressure condition exactly meets the demand of the reaction rate for hydrogen at the temperature, avoiding the accumulation of intermediates due to mass transfer limitation. The mild temperature and medium-low pressure reaction conditions inhibit the occupation of the catalyst active sites by chlorine ions from the aspects of thermodynamics and kinetics, and the two conditions synergistically avoid the accumulation of intermediates (such as phenylhydroxylamine) and the occurrence of condensation side reactions to generate byproducts such as benzene azo oxide, and jointly "lock" the extremely high reaction selectivity.

[0020] At the same time, under the premise of ensuring high conversion rate and high selectivity, the requirement for equipment and energy consumption is reduced, the safe, efficient and economical operation of the process is realized, and the needs of industrial scale production are perfectly met.

[0021] The reaction formula in the preparation process of 2,5-bis-sulfonic acid aniline sodium salt of the present application is as follows: One-step sulfonation reaction formula:

[0022] Displacement sulfonation reaction formula:

[0023] Catalytic hydrogenation reaction formula:

[0024] The application will be further described below with reference to examples. Example 1

[0025] (1) One-step sulfonation: 78.5 g (0.50 mol) of o-chloronitrobenzene was added into a reaction kettle and was melted by heating to 45°C. While controlling the temperature at 50°C, 48.0 g (0.60 mol) of sulfur trioxide was slowly added dropwise within 2 hours. After the dropwise addition was completed, the temperature was raised to 75°C and the reaction was kept for 3.5 hours; then the temperature was continuously raised to 102°C and the reaction was kept for 2.5 hours until the sulfonation was completed. The obtained sulfonated product was slowly added dropwise into 270 g (15.0 mol) of deionized water for dilution, and the temperature was set at 85°C. Then 3.14 g (4% of the mass of o-chloronitrobenzene) of activated carbon was added, and the mixture was decolored at 80°C for 45 minutes, and then was filtered to obtain a light yellow sulfonated dilution.

[0026] (2) Displacement sulfonation: 30% sodium hydroxide solution was added into the sulfonated dilution to adjust the pH of the system to 9.5. 157.5 g (1.25 mol) of sodium sulfite was added, and the displacement sulfonation reaction was carried out at 105°C under reflux for 4 hours until the end point. After the reaction was completed, the system was adjusted to neutral with concentrated hydrochloric acid.

[0027] (3) Oxidation pretreatment: 142.4 g (21.256 mol of pure H2O) of 30% hydrogen peroxide was slowly added dropwise into the above neutral reaction system within 1 hour, and the temperature was controlled at 102°C, and the reaction was kept for 1.5 hours until the oxidation was completed.

[0028] (4) Catalytic hydrogenation: 1.04 g of palladium-carbon catalyst (Pd content 5%) was added into the reaction system after the oxidation pretreatment, and the air was replaced with hydrogen three times, then hydrogen was introduced until the pressure reached 0.8 MPa, and the catalytic hydrogenation reaction was carried out at 75°C for 2.5 hours until the reduction was completed.

[0029] (5) Salting out and post-treatment: After the reduction reaction was completed, 175 g (2.99 mol) of sodium chloride was added to the reaction system for salting out, and the temperature was controlled at 38℃. Then the temperature was slowly lowered to 25℃ and kept at this temperature for 2 hours to grow crystals. After filtration, the filter cake was vacuum dried at 60℃ for 8 hours to obtain 125.2 g of white flaky crystalline sodium 2,5-disulfonic acid aniline. The purity was 99.5% as determined by HPLC, and the total yield based on o-chloronitrobenzene was 91.0%. Example 2

[0030] (1) One-step sulfonation: 78.5 g (0.50 mol) of o-chloronitrobenzene was added to the reactor and heated to 48 °C to melt it. The temperature was controlled at 55 °C, and 52.0 g (0.65 mol) of sulfur trioxide was slowly added dropwise over 2.5 hours. After the addition was completed, the temperature was raised to 78 °C and the reaction was maintained for 3 hours; then the temperature was raised to 104 °C and the reaction was maintained for 2 hours until the sulfonation endpoint was reached. The obtained sulfonated product was slowly added dropwise to 325 g (18.1 mol) of deionized water for dilution, and the temperature was set at 80 °C. Then 2.36 g (3% of the mass of o-chloronitrobenzene) of activated carbon was added, and the product was decolorized at 85 °C for 0.5 hours. After filtration, a light yellow sulfonated diluted solution was obtained.

[0031] (2) Displacement sulfonation: Add solid potassium carbonate to the sulfonation dilution solution to adjust the pH of the system to 9.2. Add 141.0 g (1.10 mol) potassium sulfite, and heat to reflux at 103 °C for 5 hours to carry out the displacement sulfonation reaction to the endpoint. After the reaction is completed, adjust the system to neutral with 50% sulfuric acid solution.

[0032] (3) Oxidation pretreatment: In the above neutral reaction system, slowly add 124.7 g (containing 1.10 mol of pure H2O) of 30% hydrogen peroxide over 1.5 hours, control the temperature at 104℃, and keep the reaction at this temperature for 1 hour until the oxidation endpoint.

[0033] (4) Catalytic hydrogenation: 0.87 g of platinum carbon catalyst (Pt content 5%) was added to the reaction system after oxidation pretreatment. After replacing the air with hydrogen three times, hydrogen was introduced to a pressure of 0.6 MPa and the temperature was controlled at 78℃ for catalytic hydrogenation reaction for 2 hours until the reduction endpoint.

[0034] (5) Salting out and post-treatment: After the reduction reaction was completed, 177.6 g (1.25 mol) of sodium sulfate was added to the reaction system for salting out, and the temperature was controlled at 36 °C. Then the temperature was slowly lowered to 20 °C and kept at that temperature for 3 hours to grow crystals. After filtration, the filter cake was vacuum dried at 65 °C for 10 hours to obtain 124.1 g of white powdered sodium 2,5-disulfonic acid aniline, with a purity of 99.2% and a total yield of 90.2% based on o-chloronitrobenzene. Example 3

[0035] (1) One-step sulfonation: 78.5 g (0.50 mol) of o-chloronitrobenzene was added to the reactor and heated to 42 °C to melt it. The temperature was controlled at 45 °C, and 56.0 g (0.70 mol) of sulfur trioxide was slowly added dropwise over 1.5 hours. After the addition was completed, the temperature was raised to 72 °C and the reaction was maintained for 4 hours; then the temperature was raised to 101 °C and the reaction was maintained for 3 hours until the sulfonation endpoint was reached. The obtained sulfonated product was slowly added dropwise to 360 g (20.0 mol) of deionized water for dilution, and the temperature was set at 80 °C. Then 3.92 g (5% of the mass of o-chloronitrobenzene) of activated carbon was added, and the product was decolorized at 75 °C for 1 hour. After filtration, a light yellow sulfonated diluted solution was obtained.

[0036] (2) Displacement sulfonation: Add 25% potassium hydroxide solution to the sulfonation dilution solution to adjust the pH of the system to 9.8. Add 189.0 g (1.50 mol) potassium sulfite, heat to 103℃ and reflux for 3.5 hours to the endpoint. After the reaction is completed, adjust the system to neutral with concentrated hydrochloric acid.

[0037] (3) Oxidation pretreatment: In the above neutral reaction system, slowly add 170.2 g (containing 1.501 mol of pure H2O) of 30% hydrogen peroxide over 1 hour, control the temperature at 101℃, and keep the reaction at this temperature for 2 hours until the oxidation endpoint.

[0038] (4) Catalytic hydrogenation: 0.785 g of platinum carbon catalyst (Pt content 5%) was added to the reaction system after oxidation pretreatment. After replacing the air with hydrogen three times, hydrogen was introduced to a pressure of 1.0 MPa and the temperature was controlled at 72℃ for catalytic hydrogenation reaction for 3 hours until the reduction endpoint.

[0039] (5) Salting out and post-treatment: After the reduction reaction was completed, 157.8 g (2.70 mol) of sodium chloride was added to the reaction system for salting out, and the temperature was controlled at 37℃. Then the temperature was slowly lowered to 22℃ and kept at this temperature for crystal growth for 2.5 hours. After filtration, the filter cake was vacuum dried at 55℃ for 12 hours to obtain 124.7 g of white crystalline 2,5-disulfonic acid aniline sodium salt product with a purity of 99.6% and a total yield of 90.6% based on o-chloronitrobenzene. Example 4

[0040] After the first reaction in Example 1, the palladium-on-carbon catalyst was recovered by filtration and used directly in the next batch. Considering the loss of catalyst during the filtration process, 1% catalyst was added each time. In subsequent batches, the catalyst recovered from the previous batch was used, and the hydrogenation and subsequent steps of Example 1 were repeated.

[0041] Record the results after applying the formula different times: The fifth application: reaction time 2.6 hours, product yield 90.7%, purity 99.5%.

[0042] 10th application: reaction time 2.8 hours, product yield 90.3%, purity 99.4%.

[0043] Application 20: Reaction time 3.0 hours, product yield 90.1%, purity 99.3%.

[0044] Even after 20 applications, the catalytic hydrogenation reaction time of the noble metal catalyst remains within 3 hours, indicating that the catalyst still maintains good catalytic activity.

Claims

1. A method for preparing sodium 2,5-bis(sulfonyl)aniline, characterized in that: The preparation method includes the following steps: (1) One-step sulfonation: o-chloronitrobenzene is added to the reaction apparatus and heated to melt. Then, sulfur trioxide is slowly added dropwise under temperature control. After the addition is complete, the temperature is raised to the first sulfonation temperature and kept at the temperature for reaction. Then, the temperature is raised to the second sulfonation temperature and kept at the temperature for reaction until the sulfonation endpoint is reached. Subsequently, the obtained sulfonated product is slowly added dropwise to a certain amount of water for dilution. Activated carbon is added for decolorization, and the diluted sulfonated solution is obtained by filtration. (2) Displacement sulfonation: Add alkali to the sulfonation dilution solution to adjust the pH of the system to 9-10, then add a certain amount of sulfite, and heat to reflux to carry out the displacement sulfonation reaction to the endpoint; after the reaction is completed, adjust the system to neutral with acid; (3) Oxidation pretreatment: A fixed amount of oxidant is slowly added dropwise to the above neutral reaction system, and the reaction is kept at the temperature until the oxidation endpoint is reached; (4) Catalytic hydrogenation: A certain amount of noble metal catalyst is added to the reaction system after oxidation pretreatment. After hydrogen replacement, hydrogen is introduced and catalytic hydrogenation reaction is carried out under the set pressure and temperature conditions until the reduction endpoint is reached. (5) Salting out and post-treatment: After the reduction reaction is completed, inorganic salt is added to the reaction system for salting out, followed by cooling and keeping warm to grow crystals, so that the product is fully separated out; after filtration and drying, the 2,5-bissulfonic acid aniline sodium salt product is obtained.

2. The method for preparing sodium 2,5-bis(sulfonyl)aniline according to claim 1, characterized in that: In step (3), the oxidant is hydrogen peroxide or peracetic acid.

3. The method for preparing sodium 2,5-bis(sulfonyl)aniline according to claim 1, characterized in that: In step (3), the temperature of the oxidation pretreatment reaction is 100-105℃ and the reaction time is 1-2 h; the molar ratio of the oxidant to the sulfite in step (2) is (1-1.1):

1.

4. The method for preparing sodium 2,5-bis(sulfonyl)aniline according to claim 1, characterized in that: In step (1), the molar ratio of o-chloronitrobenzene, sulfur trioxide and water is 1:(1.0-1.5):(30-40).

5. The method for preparing sodium 2,5-bis(sulfonyl)aniline according to claim 1, characterized in that: In step (1), the melting temperature of o-chloronitrobenzene is 40-50°C; the dropping temperature of sulfur trioxide is 40-60°C; the first sulfonation temperature is 70-80°C, and the reaction is maintained for 3-4 hours; the second sulfonation temperature is 100-105°C, and the reaction is maintained for 2-3 hours; the temperature at which the sulfonated product is diluted with water is below 100°C; the amount of activated carbon added is 2-5% of the mass of o-chloronitrobenzene; and the decolorization time is 0.5-1 hour.

6. The method for preparing sodium 2,5-bis(sulfonyl)aniline according to claim 1, characterized in that: In step (2), the alkali is one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate, and can be added in solid or solution form; the sulfite is one or more of sodium sulfite and potassium sulfite; the molar ratio of the sulfite to o-chloronitrobenzene is (2-3):1; the acid used for neutralization is concentrated hydrochloric acid or sulfuric acid; the reflux temperature is 100-105℃.

7. The method for preparing sodium 2,5-bis(sulfonyl)aniline according to claim 1, characterized in that: In step (4), the noble metal catalyst is palladium on carbon or platinum on carbon; the mass ratio of o-chloronitrobenzene to the noble metal in the noble metal catalyst is (1500-2000):1; the hydrogenation reaction temperature is 70-80℃, the hydrogen pressure is 0.5-1.0 MPa, and the reaction time is 2-3 h.

8. The method for preparing sodium 2,5-bis(sulfonyl)aniline according to claim 1, characterized in that: In step (5), the inorganic salt is sodium chloride or sodium sulfate; the molar ratio of metal ions to o-chloronitrobenzene in the inorganic salt is (5-6):1; and the salting-out operation temperature is 35-40℃.

Images