Synthetic method of environment-friendly sulfonated para-ester

Abstract

According to the environment-friendly synthetic method of the sulfonated para-ester, para-ester powder is directly dissolved in 60-70% fuming sulfuric acid, the solubility of the para-ester in the fuming sulfuric acid can be increased, side reactions generated when the dissolution rate is low are reduced, then heating sulfonation is conducted, the product sulfonated para-ester is prepared, the yield and purity are high, the purity ranges from 90% to 92%, and the yield of the sulfonated para-ester is high. The yield is about 95%, salting-out refining is not needed, the raw material consumption is low, no wastewater or waste acid is generated, the whole synthesis method is simple and low in cost, the problems of long reaction time, low yield, much waste acid water, difficulty in treatment and the like in the production process can be solved, and the method is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical technology, specifically relating to an environmentally friendly method for synthesizing para-sulfonated esters. Background Technology

[0002] Sulfonated para-ester (CAS 42986-22-1), also known as 456 or P acid, is an important chemical raw material, commonly used as a dye intermediate or pharmaceutical intermediate. Existing methods for sulfonating para-ester generally use para-ester as the main raw material, proceeding through sulfonation, hydrolysis, dilution, salting out, and pressure filtration to obtain the finished product. However, the process of sulfonation with 25-50% fuming sulfuric acid and salting out with potassium chloride generates dilute sulfuric acid wastewater containing large amounts of potassium chloride and sodium sulfate, which is difficult to treat and unsustainable; furthermore, the process is cumbersome and incurs high labor and energy costs. Therefore, it is necessary to improve existing synthetic methods and provide a clean and environmentally friendly new method for producing sulfonated para-ester. Summary of the Invention

[0003] The purpose of this invention is to provide an environmentally friendly method for synthesizing para-sulfonated esters based on existing technologies. The method involves directly dissolving para-ester powder in 60-70% fuming sulfuric acid, followed by sulfonation at elevated temperature to obtain the para-sulfonated ester product. The yield and purity are high, with a purity of 90%-92%. No salting-out purification is required, raw material consumption is low, and no wastewater or waste acid is generated. The entire synthesis method is simple and low-cost, and it can solve problems such as long reaction time, low yield, and large amounts of difficult-to-treat waste acid water in the production process, making it suitable for industrial production.

[0004] The technical solution of the present invention is as follows:

[0005] An environmentally friendly method for synthesizing para-sulfonated ester includes the following steps: slowly adding para-ester powder to 60-70 wt% fuming sulfuric acid, stirring during the entire process of adding para-ester, and controlling the temperature not to exceed 70°C. After the para-ester is added, the temperature is raised to 70-90°C for stirring and dissolution, so that the para-ester is completely dissolved. Then, the resulting mixed solution is heated to 120-140°C for sulfonation reaction. The purity of the para-sulfonated ester is measured to be 90-92%, and the acidity is 45-47%. After the reaction is completed, the product para-sulfonated ester is prepared.

[0006] For this invention, the concentration of fuming sulfuric acid is very important. Only by controlling the concentration of fuming sulfuric acid to 60-70 wt% can the purpose of this invention be achieved, and the product sulfonated para ester can be obtained with high yield and purity (90%-92%). No salting-out purification is required, raw material consumption is low, and no wastewater or waste acid is generated. The entire synthesis method is simple and low-cost, and can solve the problems of long reaction time, low yield, and large amount of difficult-to-treat waste acid water in the production process, making it suitable for industrial production.

[0007] In this invention, the concentration of fuming sulfuric acid is 60-70 wt%, which may be, but is not limited to, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, or 70 wt%. In a preferred embodiment, the concentration of fuming sulfuric acid is 62-68 wt%. More preferably, the concentration of fuming sulfuric acid is 64-66 wt%. Particularly preferably, the concentration of fuming sulfuric acid is 65 wt%.

[0008] In this invention, the weight ratio of fuming sulfuric acid to para-ester is 1:1.5-2.8, and can be, but is not limited to, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2.0, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7 or 1:2.8. In a preferred embodiment, the weight ratio of fuming sulfuric acid to para-ester is 1:1.8-2.5, and more preferably, the weight ratio of fuming sulfuric acid to para-ester is 1:2.0-2.3.

[0009] In this invention, the purity of the para-ester is ≥96%.

[0010] In this invention, the feeding time of para-ester is 2-6 hours, which can be, but is not limited to, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours. In a preferred embodiment, the feeding time of para-ester is 4 hours.

[0011] In this invention, the dissolution temperature during stirring is 70-90℃, which can be, but is not limited to, 70℃, 75℃, 80℃, 85℃ or 90℃. In a preferred embodiment, the dissolution temperature is 75-85℃, and more preferably, the dissolution temperature is 80℃.

[0012] In this invention, the dissolution time during stirring is 1-3 hours, which can be, but is not limited to, 1 hour, 2 hours or 3 hours. In a preferred embodiment, the dissolution time is 2 hours.

[0013] In this invention, the sulfonation reaction is carried out at a temperature of 120-140°C, which may be, but is not limited to, 120°C, 125°C, 130°C, 135°C or 140°C. In a preferred embodiment, the reaction temperature is 125-135°C, and more preferably, the reaction temperature is 130°C.

[0014] In this invention, the sulfonation reaction takes 4-8 hours, but is not limited to 4 hours, 5 hours, 6 hours, 7 hours or 8 hours. In a preferred embodiment, the reaction time is 6 hours.

[0015] The advantages of using the technical solution of this invention are as follows:

[0016] This invention provides an environmentally friendly method for synthesizing para-sulfonated esters. The para-ester powder is directly dissolved in 60-70% fuming sulfuric acid, which increases the solubility of the para-ester in fuming sulfuric acid and reduces the occurrence of side reactions when the dissolution rate is slow. Sulfonation is then carried out at a higher temperature to obtain the para-sulfonated ester product. The yield and purity are high, with a purity of 90%-92% and a yield of approximately 95%. No salting-out purification is required, raw material consumption is low, and no wastewater or waste acid is generated. The entire synthesis method is simple and low-cost, solving problems such as long reaction time, low yield, and large amounts of difficult-to-treat waste acid during production, making it suitable for industrial production. Detailed Implementation

[0017] The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the descriptions in the embodiments are for illustrative purposes only and should not, and will not, limit the invention as detailed in the claims.

[0018] Example 1

[0019] An environmentally friendly method for synthesizing para-sulfonated esters includes the following steps:

[0020] 376 kg of 65 wt% fuming sulfuric acid was added to the reaction vessel, and 787.8 kg of para-ester powder (96% purity) was slowly added with stirring. The temperature was controlled to not exceed 70°C throughout the addition process, and the para-ester feeding time was controlled to be 4 hours. After the para-ester feeding was completed, the temperature was raised to 80°C and stirred for 2 hours to dissolve the para-ester completely. The resulting mixture was then heated to 130°C for sulfonation reaction, which lasted for 6 hours. The purity of the sulfonated para-ester was measured to be 91.5%, and the acidity was 45.87%. After the reaction was completed, the product was cooled and pulverized to obtain 1286.5 kg of sulfonated para-ester product. The amino content was analyzed to be 72.1%, and the yield was calculated to be 95.6%.

[0021] Example 2

[0022] An environmentally friendly method for synthesizing para-sulfonated esters includes the following steps:

[0023] 376 kg of 62 wt% fuming sulfuric acid was added to the reaction vessel, and 787.8 kg of para-ester powder (96% purity) was slowly added with stirring. The temperature was controlled to not exceed 70°C throughout the addition process, and the para-ester feeding time was controlled to be 4 hours. After the para-ester feeding was completed, the temperature was raised to 80°C and stirred for 2 hours to dissolve the para-ester completely. The resulting mixture was then heated to 135°C for sulfonation reaction, which lasted 6 hours. The purity of the sulfonated para-ester was measured to be 90.8%, and the acidity was 45.3%. The reaction was then terminated. After cooling and pulverization, 1290.8 kg of the sulfonated para-ester product was obtained, with an amino content of 71.6% and a calculated yield of 95.2%.

[0024] Example 3

[0025] An environmentally friendly method for synthesizing para-sulfonated esters includes the following steps:

[0026] 376 kg of 68 wt% fuming sulfuric acid was added to the reaction vessel, and 787.8 kg of para-ester powder (96% purity) was slowly added with stirring. The temperature was controlled to not exceed 70°C throughout the addition process, and the para-ester feeding time was controlled to be 4 hours. After the para-ester feeding was completed, the temperature was raised to 80°C and stirred for 2 hours to dissolve the para-ester completely. The resulting mixture was then heated to 128°C for sulfonation reaction, which lasted for 6 hours. The purity of the sulfonated para-ester was measured to be 91.8%, and the acidity was 46.2%. The reaction was then terminated. After cooling and pulverization, 1292.6 kg of the sulfonated para-ester product was obtained, with an amino content of 71.2% and a calculated yield of 94.8%.

[0027] Comparative Example 1

[0028] An environmentally friendly method for synthesizing para-sulfonated esters includes the following steps:

[0029] 376 kg of 50 wt% fuming sulfuric acid was added to the reaction vessel, and 787.8 kg of para-ester powder (96% purity) was slowly added with stirring. The temperature was controlled to not exceed 70°C throughout the addition process, and the para-ester feeding time was controlled to be 4 hours. After the para-ester feeding was completed, the temperature was raised to 80°C and stirred for 2 hours to dissolve the para-ester completely. The resulting mixture was then heated to 135°C for sulfonation reaction, which lasted for 6 hours. The purity of the sulfonated para-ester was measured to be 88.9%, and the acidity was 45.1%. The reaction was then terminated. After cooling and pulverizing, 1289.6 kg of the sulfonated para-ester product was obtained, with an amino content of 68.5% and a calculated yield of 91%.

[0030] Comparative Example 2

[0031] An environmentally friendly method for synthesizing para-sulfonated esters includes the following steps:

[0032] 376 kg of 75 wt% fuming sulfuric acid was added to the reaction vessel, and 787.8 kg of para-ester powder (96% purity) was slowly added with stirring. The temperature was controlled to not exceed 70°C throughout the addition process, and the para-ester feeding time was controlled to be 4 hours. After the para-ester feeding was completed, the temperature was raised to 80°C and stirred for 2 hours to dissolve the para-ester completely. The resulting mixture was then heated to 130°C for sulfonation reaction, which lasted for 6 hours. The purity of the sulfonated para-ester was measured to be 89.2%, and the acidity was 46.5%. The reaction was then terminated. After cooling and pulverization, 1296.6 kg of the sulfonated para-ester product was obtained, with an amino content of 69.1% and a calculated yield of 92.3%.

[0033] Comparative Example 3

[0034] The method for synthesizing purchased sulfonated para-esters (Shandong Taian Yonghe Chemical Co., Ltd., Inner Mongolia Liyuan Technology Co., Ltd.) includes the following steps:

[0035] Add 1736 kg of 25 wt% fuming sulfuric acid to the reaction vessel, start stirring, turn on the jacket cooling water, and cool to 30°C. Slowly add 787.8 kg of para-ester powder (96% purity), controlling the temperature not to exceed 45-55°C throughout the entire para-ester addition process. The material is quite viscous, so control the para-ester addition time to 3-4 hours. After the addition is complete, continue stirring for 1-2 hours to ensure complete dissolution. After complete dissolution, slowly raise the temperature to 80°C, reduce the steam valve, and allow the reactor temperature to naturally rise to 120-125°C for 6-8 hours. Take samples for chromatographic analysis (acidity approximately 70%, liquid phase purity 79.2%, with 39.8% monosulfonate peak, 39.4% bissulfonate peak, and raw material peak <1.5% is acceptable). After passing the test, cool to 60°C and prepare for hydrolysis and dilution.

[0036] Place 500L of bottom water (adjust the amount of ice water according to seasonal changes) in an 8000L dilution vessel, turn on the stirrer, and lower the temperature inside the vessel to below 15℃. At the same time, add crushed ice, open the bottom valve of the sulfonation vessel, and slowly dilute (the dilution time is 2 hours), keeping the temperature controlled at 15-20℃ throughout.

[0037] After dilution, the total volume was adjusted to 5000 L, with an analytical volume content of 13% and an acidity of 30%. 500 kg of potassium salt was slowly added (approximately 2 hours), and stirring continued for another 2 hours. The mixture was then cooled to 15°C, and the volume was reduced to 5500 L before pressure filtration. The mixture was then air-blown, discharged, crushed, weighed, and packaged to obtain 1320.8 kg of sulfonated para-ester wet product. Analysis showed an amino content of 65.1%, an acidity of 24.5%, and a liquid phase purity of 88.5%, with a calculated yield of 88.6%.

[0038] The sulfonated para-esters obtained in the examples and comparative examples were compared by liquid chromatography, content and acidity detection. The results are shown in Table 1.

[0039] Table 1 shows the liquid chromatography, content, and acidity determination of the sulfonated para-esters obtained in the examples and comparative examples.

[0040] sample Liquid phase purity % content% acidity% Yield % Example 1 91.5 72.1 45.87 95.6 Example 2 90.8 71.6 45.3 95.2 Example 3 91.8 71.2 46.2 94.8 Comparative Example 1 88.9 68.5 45.1 91 Comparative Example 2 89.2 69.1 46.5 92.3 Comparative Example 3 88.5 65.1 24.5 88.6

[0041] As can be seen from the test results of the examples and comparative examples in Table 1, the purity of the products disclosed in Examples 1-3 of this invention is 90.8%-91.8%, and the average yield is 95.2%. In Comparative Examples 1 and 2, when the content of fuming sulfuric acid is 50wt% and 75wt%, respectively, the purity measured at the reaction endpoint is 88.9% and 89.2%, with an average yield of 91.7%. A low content of fuming sulfuric acid makes it difficult to reach the sulfonation endpoint, results in a longer reaction time, and slightly lower product purity; a high content of fuming sulfuric acid leads to high viscosity of the reactants, making stirring difficult, making it difficult to reach the sulfonation endpoint, resulting in a longer reaction time and slightly lower product purity. Compared with Examples 1-3, Comparative Examples 1 and 2 have a 2.3% lower purity at the sulfonation endpoint and a 3.5% lower average yield.

[0042] Comparative Example 3 synthesized sulfonated para-ester using 25 wt% fuming sulfuric acid, with a final purity of 79.2%. The sulfonated para-ester product was obtained through hydrolysis, dilution, salting out, and pressure filtration, achieving a purity of 88.5% and a yield of 88.6%. Compared to Examples 1-3, the product purity was 2.8% lower and the yield was 6.6% lower. Compared to Examples 1-3, Comparative Example 3 used 25 wt% fuming sulfuric acid for sulfonation, a 3.6-fold increase in dosage, and the final purity was 12.1% lower. Only through complex processes such as hydrolysis, dilution, salting out, and pressure filtration could the product purity be improved to 88.5%, meeting the requirements for synthetic dyes. Furthermore, the potassium chloride salting-out process generates dilute sulfuric acid wastewater containing large amounts of potassium chloride and sodium sulfate, which is difficult to treat and unsustainable; it also incurs significant labor and energy costs.

[0043] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications may still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions may be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An environmentally friendly method for synthesizing sulfonated para-esters, characterized in that, Includes the following steps: Para-ester powder is slowly added to 60-70 wt% fuming sulfuric acid. Stirring is started during the entire process of adding para-ester, and the temperature is controlled not to exceed 70℃. After the para-ester is added, the temperature is raised to 70-90℃ and stirred to dissolve it completely. Then the resulting mixed solution is heated to 120-140℃ to carry out the sulfonation reaction. The purity of the sulfonated para-ester is measured to be 90-92%, and the acidity is 45-47%. The reaction is then completed, and the product sulfonated para-ester is prepared.

2. The synthesis method according to claim 1, characterized in that, The concentration of the fuming sulfuric acid is 62-68 wt%.

3. The synthesis method according to claim 2, characterized in that, The concentration of the fuming sulfuric acid is 64-66 wt%.

4. The synthesis method according to claim 3, characterized in that, The concentration of the fuming sulfuric acid is 65 wt%.

5. The synthesis method according to claim 1, characterized in that, The weight ratio of the fuming sulfuric acid to the para-ester is 1:1.5-2.8, preferably 1:1.8-2.5, and more preferably 1:2.0-2.3; the purity of the para-ester is ≥96%.

6. The synthesis method according to claim 1, characterized in that, The feeding time for para-ester is 2-6 hours; preferably 4 hours.

7. The synthesis method according to claim 1, characterized in that, When stirring to dissolve, the dissolution temperature is 75-85℃, preferably 80℃.

8. The synthesis method according to claim 1, characterized in that, When stirring to dissolve, the dissolving time is 1-3 hours, preferably 2 hours.

9. The synthesis method according to claim 1, characterized in that, During the sulfonation reaction, the reaction temperature is 125-135℃, preferably 130℃.

10. The synthesis method according to claim 1, characterized in that, During the sulfonation reaction, the reaction time is 4-8 hours, preferably 6 hours.