Method for producing 2B acid by compounding multiple solvents
By using multiple solvents in the production of 2B acids and introducing polyethylene glycol 400 and anhydrous sodium sulfate, the problem of increasing by-products caused by mismatch in the solvent reaction temperature and large viscosity of the reaction system in the prior art is solved, and the problem of increasing by-products caused by mismatch in the solvent reaction temperature and the reaction system is achieved. High purity, high whiteness and high bulk density 2B acid production reduces production costs.
Patent Information
- Application Number
- CN202411589491.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-08
- Publication Date
- 2025-02-18
AI Technical Summary
In the prior art, when using ortho-dichlorobenzene as a solvent, it is difficult to reach the optimal reaction temperature of 2B oil under normal pressure, resulting in incomplete reaction; and although the addition of trichlorobenzene can achieve the reaction temperature standard, the reaction system has a relatively large viscosity. , the material is easily sticky, resulting in an increase in by-products and needs to be removed through refining, which increases production costs.
Methods for producing 2B acids by using a variety of solvent compounding, including the use of a combination of compound solvents such as o-dichlorobenzene/trichlorobenzene/solvent oil D60, and the introduction of polyethylene glycol 400 as catalyst and anhydrous sodium sulfate as side reaction inhibition to improve reaction efficiency and product purity.
Through solvent compounding and the use of catalysts and inhibitors, the purity, whiteness and bulk density of 2B acids are improved, the generation of by-products is reduced, and the production cost is reduced.
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Figure CN119462436A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of 2B acid production, and specifically to a method for producing 2B acid by compounding multiple solvents. Background Art
[0002] 3-Chloro-p-toluidine-6-sulfonic acid, also known as 2B acid, is a white or pink powder and is one of the eight most important varieties of organic pigment intermediates today. In the preparation of 2B acid, 2B oil (3-chloro-4-methylaniline) is used as a raw material, o-dichlorobenzene or trichlorobenzene is used as a solvent, and concentrated sulfuric acid is usually used as a sulfonating agent to carry out sulfonation salt formation, dehydration and transposition reactions to obtain a sulfonated product, which is then subjected to liquid alkali hydrolysis, decolorization, filtration, acid precipitation crystallization, dehydration, drying and other refining processes to obtain high-purity 2B acid.
[0003] However, it is difficult to reach the optimal reaction temperature of 2B oil under normal pressure using o-dichlorobenzene as solvent, resulting in incomplete reaction. Although adding trichlorobenzene can make the reaction temperature reach the standard, the viscosity of the reaction system is relatively large, and the material is easy to stick to the kettle, resulting in an increase in by-products, which need to be removed by refining, increasing production costs. Based on this, a method for producing 2B acid by compounding multiple solvents is proposed. Summary of the invention
[0004] In view of the shortcomings of the prior art, the present invention provides a method for producing 2B acid by compounding multiple solvents. By compounding o-dichlorobenzene / trichlorobenzene / solvent oil D60 and introducing a new catalyst polyethylene glycol 400 and anhydrous sodium sulfate, a sulfone side reaction inhibitor, the produced 2B acid product has high purity and whiteness, and also improves the bulk density.
[0005] To achieve the above object, the present invention provides the following technical solution: a method for producing 2B acid by compounding multiple solvents, comprising the following steps:
[0006] (1) Add 2B oil and compound solvent into the sulfonation kettle and mix them evenly;
[0007] (2) adding concentrated sulfuric acid dropwise to the sulfonation kettle, raising the temperature to above 100° C. after the addition is completed to carry out the sulfonation reaction, adding a catalyst and a side reaction inhibitor at the initial stage of the reaction, and transferring the material to a baking kettle after the reaction is completed, first raising the temperature to above 160° C. for heat preservation and dehydration, and then raising the temperature to above 185° C. for heat preservation and reaction, during which the gas phase discharge is condensed and water is separated, and the solvent is refluxed;
[0008] (3) After the heat preservation reaction is completed, sampling is performed to detect that the amino value is greater than 98.0%, and then the mixture is cooled, filtered, washed with water, and dried to obtain 2B acid.
[0009] Preferably, in step (1), the compound solvent comprises the following components, by mass percentage: 20-60% of o-dichlorobenzene, 20-40% of trichlorobenzene, and 20-40% of solvent oil D60.
[0010] Preferably, in steps (1)-(2), the mass ratio of 2B oil to the compound solvent is 1:(2-4); the mass ratio of the catalyst to the 2B oil is (0.002-0.003):1; the mass ratio of the side reaction inhibitor to the 2B oil is (0.002-0.003):1; and the mass concentration of the 2B oil is 99.5%.
[0011] Preferably, in steps (1)-(2), the molar ratio of 2B oil to concentrated sulfuric acid is 1:(1-1.05); and the mass concentration of concentrated sulfuric acid is 98%.
[0012] Preferably, in step (2), the catalyst is polyethylene glycol 400; and the side reaction inhibitor is anhydrous sodium sulfate.
[0013] Preferably, in step (2), during the dropwise addition of concentrated sulfuric acid, the system temperature is controlled to be lower than 100° C.; during the sulfonation reaction, the reaction temperature is controlled to be 100-140° C., and the reaction time is 2-3 h.
[0014] Preferably, in step (2), the temperature of the thermal insulation and dehydration is 160-175° C., and the time of the thermal insulation and dehydration is 2-3 h.
[0015] Preferably, in step (2), the temperature of the insulation reaction is 185-195° C., and the insulation reaction time is 9-11 h.
[0016] The present invention provides a method for producing 2B acid by compounding multiple solvents, which has the following advantages compared with the prior art:
[0017] Beneficial effects:
[0018] The present invention adopts o-dichlorobenzene / trichlorobenzene / solvent oil D60 for compounding and use, thereby improving the quality of the final product 2B acid. Wherein, when o-dichlorobenzene is used as a solvent, the normal pressure reaction temperature is 180°C, while the preferred reaction temperature of 2B oil is above 185°C, and the low temperature causes an incomplete reaction, so trichlorobenzene is added for reconciliation to reach a higher reaction temperature, the reaction is more thorough, and the product quality is better, but the viscosity of the reaction system of trichlorobenzene as a solvent is relatively large, and the material is easy to stick to the kettle, resulting in an increase in by-products, and then by adding solvent oil D60 as a small polar solvent, the viscosity of the reaction system can be reduced, and the dispersibility of the compound solvent can be significantly improved by being mixed into the compound solvent of o-dichlorobenzene and trichlorobenzene, and the sulfonation reaction effect is further improved, and the purity and whiteness of the produced 2B acid product are relatively high, and the particle size is relatively small, that is, the bulk density is improved.
[0019] In the present invention, polyethylene glycol 400 is added as a catalyst during the reaction process to promote the reaction of 2B oil and sulfuric acid, accelerate the reaction rate, improve the reaction selectivity, and has good water solubility and can be removed by washing with water; anhydrous sodium sulfate is added as a side reaction inhibitor to inhibit the generation of the byproduct sulfone and improve the purity of 2B acid. Since the product 2B acid will further react with sulfuric acid to generate aromatic sulfone cations under high temperature and high concentration of sulfonating agent, and then will combine with benzene compounds such as 2B oil and 2B acid to generate sulfone, by adding anhydrous sodium sulfate to the system, it can dissociate hydrogen sulfate ions in an acidic medium, so that the side reaction balance moves to the left, thereby inhibiting the side reaction, reference: ArSO 3 H+2H 2 SO 4 →ArSO 2 + +H 3 O + +2HSO 4 - 、ArSO 2 + +ArH→ArSO 2 Ar+H + . BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:
[0021] Figure 1 This is a comparison chart of 2B acid with 55 whiteness and 75 whiteness in the present invention;
[0022] Figure 2 The whiteness is 75 and the whiteness is 0.4 g / cm 3 Bulk density graph of 2B acid sample. DETAILED DESCRIPTION
[0023] The following examples are used to explain the implementation methods of the present application in detail, so that the implementation process of how the present application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.
[0024] Example 1
[0025] A method for producing 2B acid by compounding multiple solvents: 695 kg of 99.5 wt% 2B oil and 1400 kg of compounded solvent are added into a sulfonation kettle, 509 kg of 98 wt% concentrated sulfuric acid is added dropwise over 30 minutes, cooling water is passed into the jacket of the sulfonation kettle to control the temperature below 100°C, 1.39 kg of polyethylene glycol 400 and 1.39 kg of anhydrous sodium sulfate are added after the addition is completed, and the temperature is raised to 135°C for reaction for 2 hours, and then the material is transferred to a baking kettle, firstly heated to 171°C for insulation and dehydration for 2 hours, and then heated to 190°C for insulation and reaction for 10 hours, during which the gas phase discharge is condensed and separated, the solvent is refluxed, and when the amino value is greater than 98.0%, the sample is cooled, filtered, washed with water, and vacuum dried at 100°C for 2 hours to obtain 2B acid.
[0026] The compound solvent is composed of o-dichlorobenzene, trichlorobenzene and solvent oil in a mass ratio of 1:2:2.
[0027] The obtained product has a whiteness of 74 and a bulk density of 0.42 g / cm 3 , purity 2B acid 99.6%, 2B oil 0.2%.
[0028] Example 2
[0029] A method for producing 2B acid by compounding multiple solvents: 687 kg of 99.5 wt% 2B oil and 1900 kg of compounded solvent are added into a sulfonation kettle, 498 kg of 98 wt% concentrated sulfuric acid is added dropwise over 30 minutes, cooling water is passed into the jacket of the sulfonation kettle to control the temperature below 100°C, 1.72 kg of polyethylene glycol 400 and 1.72 kg of anhydrous sodium sulfate are added after the addition is completed, and the temperature is raised to 120°C for reaction for 2.5 hours, and then the material is transferred to a baking kettle, firstly heated to 162°C for insulation and dehydration for 3 hours, and then heated to 188°C for insulation and reaction for 10 hours, during which the gas phase discharge is condensed and water is separated, the solvent is refluxed, and when the sample is tested for the amino value>98.0%, it is cooled, filtered, washed with water, and vacuum dried at 100°C for 2 hours to obtain 2B acid.
[0030] The compound solvent is composed of o-dichlorobenzene, trichlorobenzene and solvent oil D60 in a mass ratio of 4:3:3.
[0031] The obtained product has a whiteness of 77 and a bulk density of 0.43 g / cm 3 , purity 2B acid 99.7%, 2B oil 0.2%.
[0032] Example 3
[0033] A method for producing 2B acid by compounding multiple solvents: 701 kg of 99.5 wt% 2B oil and 2500 kg of compounded solvent are added into a sulfonation kettle, 494 kg of 98 wt% concentrated sulfuric acid is added dropwise over 30 minutes, cooling water is passed into the jacket of the sulfonation kettle to control the temperature below 100°C, 2.10 kg of polyethylene glycol 400 and 2.10 kg of anhydrous sodium sulfate are added after the addition is completed, and the temperature is raised to 110°C for reaction for 3 hours, and then the material is transferred to a baking kettle, first heated to 160°C for insulation and dehydration for 3 hours, and then heated to 183°C for insulation and reaction for 11 hours, during which the gas phase discharge is condensed and water is separated, the solvent is refluxed, and when the sample is tested for the amino value>98.0%, it is cooled, filtered, washed with water, and vacuum dried at 100°C for 2 hours to obtain 2B acid.
[0034] The compound solvent is composed of o-dichlorobenzene, trichlorobenzene and solvent oil D60 in a mass ratio of 3:1:1.
[0035] The obtained product has a whiteness of 79 and a bulk density of 0.38 g / cm 3 , purity 2B acid 99.6%, 2B oil 0.2%.
[0036] Example 4
[0037] A method for producing 2B acid by compounding multiple solvents: 695 kg of 99.5 wt% 2B oil and 2300 kg of compounded solvent are added into a sulfonation kettle, 494 kg of 98 wt% concentrated sulfuric acid is added dropwise over 30 minutes, cooling water is passed into the jacket of the sulfonation kettle to control the temperature below 100°C, 1.39 kg of polyethylene glycol 400 and 1.39 kg of anhydrous sodium sulfate are added after the addition is completed, and the temperature is raised to 110°C for reaction for 3 hours, and then the material is transferred to a baking kettle, first heated to 173°C for insulation and dehydration for 2 hours, and then heated to 185°C for insulation and reaction for 11 hours, during which the gas phase discharge is condensed and water is separated, the solvent is refluxed, and when the sample is tested for the amino value>98.0%, it is cooled, filtered, washed with water, and vacuum dried at 100°C for 2 hours to obtain 2B acid.
[0038] The compound solvent is composed of o-dichlorobenzene, trichlorobenzene and solvent oil D60 in a mass ratio of 2:1:1.
[0039] The obtained product has a whiteness of 75 and a bulk density of 0.40 g / cm 3 , purity 2B acid 99.5%, 2B oil 0.2%.
[0040] Comparative Example 1
[0041] A method for producing 2B acid by compounding multiple solvents: 698 kg of 99.5 wt% 2B oil and 1500 kg of compounded solvent are added into a sulfonation kettle, 499 kg of 98 wt% concentrated sulfuric acid is added dropwise over 30 minutes, cooling water is passed into the jacket of the sulfonation kettle to control the temperature below 100°C, 1.75 kg of polyethylene glycol 400 and 1.75 kg of anhydrous sodium sulfate are added after the addition is completed, and the temperature is raised to 115°C for reaction for 2.5 hours, and then the material is transferred to a baking kettle, first heated to 170°C for insulation and dehydration for 2 hours, and then heated to 188°C for insulation and reaction for 10 hours, during which the gas phase discharge is condensed and water is separated, the solvent is refluxed, and when the sample is tested for the amino value>98.0%, it is cooled, filtered, washed with water, and vacuum dried at 100°C for 2 hours to obtain 2B acid.
[0042] The compound solvent is composed of o-dichlorobenzene and trichlorobenzene in a mass ratio of 2:3.
[0043] The obtained product has a whiteness of 67 and a bulk density of 0.29 g / cm 3 , purity 2B acid 99.7%, 2B oil 0.1%.
[0044] Comparative Example 2
[0045] A method for producing 2B acid by compounding multiple solvents: 705 kg of 99.5 wt% 2B oil and 2200 kg of compounded solvent are added into a sulfonation kettle, 511 kg of 98 wt% concentrated sulfuric acid is added dropwise over 30 minutes, cooling water is passed into the jacket of the sulfonation kettle to control the temperature below 100°C, 1.53 kg of polyethylene glycol 400 and 1.53 kg of anhydrous sodium sulfate are added after the addition is completed, and the temperature is raised to 105°C for reaction for 3 hours, and then the material is transferred to a baking kettle, first heated to 166°C for insulation and dehydration for 2.5 hours, and then heated to 186°C for insulation and reaction for 11 hours, during which the gas phase discharge is condensed and water is separated, the solvent is refluxed, and when the sample is tested for the amino value>98.0%, it is cooled, filtered, washed with water, and vacuum dried at 100°C for 2 hours to obtain 2B acid.
[0046] The compound solvent is composed of o-dichlorobenzene and trichlorobenzene in a mass ratio of 3:2.
[0047] The obtained product has a whiteness of 71 and a bulk density of 0.33 g / cm 3 , purity 2B acid 99.75%, 2B oil 0.05%.
[0048] Comparative Example 3
[0049] A method for producing 2B acid by compounding multiple solvents: 500 kg of 99.5 wt% 2B oil and 1600 kg of compounded solvent are added into a sulfonation kettle, 360 kg of 98 wt% concentrated sulfuric acid is added dropwise over 30 minutes, cooling water is passed into the jacket of the sulfonation kettle to control the temperature below 100°C, 1 kg of polyethylene glycol 400 and 1 kg of anhydrous sodium sulfate are added after the addition is completed, and the temperature is raised to 110°C for reaction for 3 hours, and then the material is transferred to a baking kettle, firstly heated to 168°C for insulation and dehydration for 2.5 hours, and then heated to 185°C for insulation and reaction for 11 hours, during which the gas phase discharge is condensed and water is separated, the solvent is refluxed, and when the sample is tested for the amino value>98.0%, it is cooled, filtered, washed with water, and vacuum dried at 100°C for 2 hours to obtain 2B acid.
[0050] The compound solvent is composed of o-dichlorobenzene and solvent oil D60 in a mass ratio of 1:1.
[0051] The obtained product has a whiteness of 70 and a bulk density of 0.40 g / cm 3 , purity 2B acid 99.5%.
[0052] Comparative Example 4
[0053] A method for producing 2B acid by compounding multiple solvents: 500 kg of 99.5 wt% 2B oil and 1300 kg of compounded solvent are added into a sulfonation kettle, 357 kg of 98 wt% concentrated sulfuric acid is added dropwise over 30 minutes, cooling water is passed into the jacket of the sulfonation kettle to control the temperature below 100°C, 1.2 kg of polyethylene glycol 400 and 1.2 kg of anhydrous sodium sulfate are added after the addition is completed, and the temperature is raised to 110°C for reaction for 3 hours, and then the material is transferred to a baking kettle, firstly heated to 171°C for insulation and dehydration for 2 hours, and then heated to 190°C for insulation and reaction for 10 hours, during which the gas phase discharge is condensed and water is separated, the solvent is refluxed, and when the sample is tested for the amino value>98.0%, it is cooled, filtered, washed with water, and vacuum dried at 100°C for 2 hours to obtain 2B acid.
[0054] The compound solvent is composed of trichlorobenzene and solvent oil D60 in a mass ratio of 1:1.
[0055] The obtained product has a whiteness of 65 and a bulk density of 0.38 g / cm 3 , purity 2B acid 99.1%.
[0056] Comparative Example 5
[0057] The method for producing 2B acid is as follows: 500 kg of 99.5 wt% 2B oil and 1800 kg of o-dichlorobenzene solvent are added into a sulfonation kettle, 365 kg of 98 wt% concentrated sulfuric acid is added dropwise over 30 minutes, cooling water is passed into the jacket of the sulfonation kettle to control the temperature below 100°C, 1.5 kg of polyethylene glycol 400 and 1.5 kg of anhydrous sodium sulfate are added after the addition is completed, and the temperature is raised to 100°C for reaction for 3 hours, and then the material is transferred to a baking kettle, first heated to 169°C for dehydration for 2.5 hours, and then heated to 185°C for reaction for 11 hours, during which the gas phase discharge is condensed and separated, the solvent is refluxed, and when the amino value is greater than 98.0%, the sample is cooled, filtered, washed with water, and vacuum dried at 100°C for 2 hours to obtain 2B acid.
[0058] The obtained product has a whiteness of 60 and a bulk density of 0.35 g / cm 3 , purity 2B acid 99.5%.
[0059] Comparative Example 6
[0060] The method for producing 2B acid is as follows: 500 kg of 99.5 wt% 2B oil and 2000 kg of solvent oil D60 are added into a sulfonation kettle, 368 kg of 98 wt% concentrated sulfuric acid is added dropwise over 30 minutes, cooling water is passed into the jacket of the sulfonation kettle to control the temperature below 100°C, 1 kg of polyethylene glycol 400 and 1 kg of anhydrous sodium sulfate are added after the addition is completed, and the temperature is raised to 100°C for reaction for 3 hours, and then the material is transferred to a baking kettle, first heated to 171°C for dehydration for 2 hours, and then heated to 192°C for reaction for 10 hours, during which the gas phase discharge is condensed and separated, the solvent is refluxed, and when the amino value is greater than 98.0%, the sample is cooled, filtered, washed with water, and vacuum dried at 100°C for 2 hours to obtain 2B acid.
[0061] The obtained product has a whiteness of 50 and a bulk density of 0.40 g / cm 3 , purity 2B acid 98.1%.
[0062] Comparative Example 7
[0063] The method for producing 2B acid is as follows: 500 kg of 99.5 wt% 2B oil and 1200 kg of trichlorobenzene solvent are added into a sulfonation kettle, 361 kg of 98 wt% concentrated sulfuric acid is added dropwise over 30 minutes, cooling water is passed into the jacket of the sulfonation kettle to control the temperature below 100°C, 1.3 kg of polyethylene glycol 400 and 1.3 kg of anhydrous sodium sulfate are added after the addition is completed, and the temperature is raised to 100°C for reaction for 3 hours, and then the material is transferred to a baking kettle, first heated to 171°C for dehydration for 2 hours, and then heated to 194°C for reaction for 9 hours, during which the gas phase discharge is condensed and separated, the solvent is refluxed, and when the sample is tested for the amino value>98.0%, it is cooled, filtered, washed with water, and vacuum dried at 100°C for 2 hours to obtain 2B acid.
[0064] The obtained product has a whiteness of 55 and a bulk density of 0.2 g / cm 3 , purity 2B acid 98.5%.
[0065] Comparative Example 8
[0066] A method for producing 2B acid by compounding multiple solvents: 695 kg of 99.5 wt% 2B oil and 1400 kg of compounded solvent are added into a sulfonation kettle, 509 kg of 98 wt% concentrated sulfuric acid is added dropwise over 30 minutes, cooling water is passed into the jacket of the sulfonation kettle to control the temperature below 100°C, 1.39 kg of polyethylene glycol 400 is added after the addition is completed, and the temperature is raised to 135°C for reaction for 2 hours, and then the material is transferred to a baking kettle, first heated to 171°C for insulation and dehydration for 2 hours, and then heated to 190°C for insulation and reaction for 10 hours, during which the gas phase discharge is condensed and water is separated, the solvent is refluxed, and when the sample is tested for the amino value>98.0%, it is cooled, filtered, washed with water, and vacuum dried at 100°C for 2 hours to obtain 2B acid.
[0067] The compound solvent is composed of o-dichlorobenzene, trichlorobenzene and solvent oil in a mass ratio of 1:2:2.
[0068] The obtained product has a whiteness of 69 and a bulk density of 0.42 g / cm 3 , purity 2B acid 99.0%, 2B oil 0.2%.
[0069] Compared with the product in Example 1, the purity of the 2B acid in this comparative example is reduced, indicating that in the absence of anhydrous sodium sulfate, the degree of side reactions is relatively high.
[0070] Comparative Example 9
[0071] A method for producing 2B acid by compounding multiple solvents: 695 kg of 99.5 wt% 2B oil and 1400 kg of compounded solvent are added into a sulfonation kettle, 509 kg of 98 wt% concentrated sulfuric acid is added dropwise over 30 minutes, cooling water is passed into the jacket of the sulfonation kettle to control the temperature below 100°C, 1.39 kg of anhydrous sodium sulfate is added after the addition is completed, and the temperature is raised to 135°C for reaction for 2 hours, then the material is transferred to a baking kettle, firstly heated to 171°C for insulation and dehydration for 2 hours, and then heated to 190°C for insulation and reaction for 12 hours, during which the gas phase discharge is condensed and water is separated, the solvent is refluxed, and when the sample is tested for the amino value>98.0%, it is cooled, filtered, washed with water, and vacuum dried at 100°C for 2 hours to obtain 2B acid.
[0072] The compound solvent is composed of o-dichlorobenzene, trichlorobenzene and solvent oil in a mass ratio of 1:2:2.
[0073] The obtained product: whiteness 71, bulk density 0.41g / cm3, purity 2B acid 99.3%, 2B oil 0.2%.
[0074] Compared with the product in Example 1, the heat preservation reaction time in this comparative example was extended by 2 h, and the purity of 2B acid was slightly decreased, indicating that the use of polyethylene glycol 400 can improve the reaction rate and reaction selectivity.
[0075] Testing standards and data statistics
[0076] Relevant tests were carried out using the products obtained in Examples 1-4 and Comparative Examples 1-8 as test objects.
[0077] 1. Whiteness determination: The whiteness of the above-mentioned product was tested using a YQ-Z-48B whiteness tester;
[0078] 2. Purity determination: Use liquid chromatography to detect the purity of the above-obtained product;
[0079] 3. Bulk density determination: Use a bulk density meter to test the bulk density of the above-obtained product;
[0080] 4. Determination of amino value: weigh 0.5g (0.0001g) of the corresponding product in a 500mL beaker, add 10mL of 10% ammonia water, and add a small amount of hot water. For 2B acid sodium salt, no ammonia water is needed, only a small amount of hot water is added. After the corresponding product is completely dissolved, add 150mL of pure water. Then add 40mL of 1+1 hydrochloric acid, 3g of potassium bromide, and ice cubes to keep the solution temperature at 0-5℃. Stir while titrating with 0.1mol / L sodium nitrite standard solution. At the beginning of titration, the tip of the burette extends below the liquid surface. Add 98% of the total required amount at one time, then lift the tip of the burette from the liquid surface and rinse with a small amount of pure water. Add the newly prepared starch-potassium iodide indicator to the reaction plate, use a glass rod to dip the reaction solution in the beaker and drop it into the indicator on the reaction plate. If the indicator immediately turns slightly blue, keep stirring for 5 minutes, and check in the same way that it is still slightly blue, it is the end point. Otherwise, titration is still required. The amino value is calculated using the following formula:
[0081]
[0082] Where, X——amino value content in the product, %;
[0083] C——concentration of standard solution, mol / L;
[0084] V——the volume of standard solution consumed, ml;
[0085] m——the mass of the product, g;
[0086] M——with 1.00mol NaNO 2 (1mol / L) equivalent product mass (2B acid 0.2215, 2B acid sodium 0.24364, 4B acid 0.1872).
[0087] The measurement results are shown in the following table:
[0088] Table 1 Measurement data statistics
[0089] category Whiteness <![CDATA[Bulk density, g / cm 3 > purity,% Amino value, % Example 1 74 0.42 99.6 98.1 Example 2 77 0.43 99.7 98.4 Example 3 79 0.38 99.6 98.3 Example 4 75 0.40 99.5 98.2 Comparative Example 1 67 0.29 99.7 98.1 Comparative Example 2 71 0.33 99.75 98.2 Comparative Example 3 70 0.40 99.5 98.2 Comparative Example 4 65 0.38 99.1 98.0 Comparative Example 5 60 0.35 99.5 98.2 Comparative Example 6 50 0.40 98.1 98.0 Comparative Example 7 55 0.20 98.5 98.0 Comparative Example 8 69 0.42 99.0 98.0 Comparative Example 9 71 0.41 99.3 98.0
[0090] It can be seen from the above table that the whiteness and bulk density of 2B acid in Comparative Examples 1-7 are generally worse than those in the examples, indicating that the three-way combination of o-dichlorobenzene / trichlorobenzene / solvent oil D60 is better than the combination of two or the use alone. Compared with Example 1, the purity of 2B acid in Comparative Example 8 is reduced, indicating that the side reaction degree is relatively deep in the absence of anhydrous sodium sulfate. Compared with Example 1, the insulation reaction time in Comparative Example 9 is extended, and the purity of 2B acid is also slightly reduced, indicating that the use of polyethylene glycol 400 can improve the reaction rate and reaction selectivity.
[0091] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A method for producing 2B acid by compounding multiple solvents, characterized in that: The following steps are involved: (1) Add 2B oil and compound solvent into the sulfonation kettle and mix them evenly; (2) adding concentrated sulfuric acid dropwise to the sulfonation kettle, raising the temperature to above 100° C. after the addition is completed to carry out the sulfonation reaction, adding a catalyst and a side reaction inhibitor at the initial stage of the reaction, and transferring the material to a baking kettle after the reaction is completed, first raising the temperature to above 160° C. for heat preservation and dehydration, and then raising the temperature to above 185° C. for heat preservation and reaction, during which the gas phase discharge is condensed and water is separated, and the solvent is refluxed; (3) After the heat preservation reaction is completed, sampling is performed to detect that the amino value is greater than 98.0%, and then the mixture is cooled, filtered, washed with water, and dried to obtain 2B acid.
2. The method for producing 2B acid by compounding multiple solvents according to claim 1, characterized in that: In step (1), the compound solvent includes the following components by mass percentage: 20-60% of o-dichlorobenzene, 20-40% of trichlorobenzene, and 20-40% of solvent oil D60.
3. The method for producing 2B acid by compounding multiple solvents according to claim 1, characterized in that: In steps (1)-(2), the mass ratio of 2B oil to the compound solvent is 1:(2-4); the mass ratio of the catalyst to the 2B oil is (0.002-0.003):1; the mass ratio of the side reaction inhibitor to the 2B oil is (0.002-0.003):1; and the mass concentration of the 2B oil is 99.5%.
4. The method for producing 2B acid by compounding multiple solvents according to claim 1, characterized in that: In steps (1)-(2), the molar ratio of 2B oil to concentrated sulfuric acid is 1:(1-1.05); and the mass concentration of concentrated sulfuric acid is 98%.
5. The method for producing 2B acid by compounding multiple solvents according to claim 1, characterized in that: In step (2), the catalyst is polyethylene glycol 400; and the side reaction inhibitor is anhydrous sodium sulfate.
6. The method for producing 2B acid by compounding multiple solvents according to claim 1, characterized in that: In step (2), during the addition of concentrated sulfuric acid, the system temperature is controlled to be lower than 100° C.; during the sulfonation reaction, the reaction temperature is controlled to be 100-140° C., and the reaction time is 2-3 hours.
7. The method for producing 2B acid by compounding multiple solvents according to claim 1, characterized in that: In step (2), the temperature of the thermal insulation and dehydration is 160-175° C., and the time of the thermal insulation and dehydration is 2-3 hours.
8. The method for producing 2B acid by compounding multiple solvents according to claim 1, characterized in that: In step (2), the temperature of the insulation reaction is 185-195° C., and the insulation reaction time is 9-11 hours.