Green production method of sulfonated para-ester

Abstract

The invention provides a green production method of sulfonated para-ester. The production method comprises the following steps: step 1, adding ethyl p-nitrobenzoate, a sulfonating agent and a solvent into a microwave reaction kettle for closed reaction, and cooling to room temperature after the reaction is finished to obtain a reaction solution; step 2, carrying out vacuum filtration on the reaction liquid, and respectively collecting filtrate and a solid catalyst; and step 3, adding a sodium carbonate solution into the filtrate, and separating out sulfonated para-ester. According to the green production method of sulfonated para-ester provided by the invention, a microwave-assisted sulfonation process is adopted, the selectivity of the product is improved, the reaction time is shortened, the energy consumption is reduced, and the yield can be increased to 20-25% through microwave action on reaction substances, rapid and uniform heating, precise temperature control and reduction of by-products generated by transitional sulfonation; compared with the traditional concentrated sulfuric acid sulfonation process, the energy consumption is reduced by 60%, the sulfonating agent after the reaction can be recycled, no waste acid is discharged, and meanwhile, non-toxic solvent water and ethanol are used for replacing methylbenzene and DMF, so that green production is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of dye intermediates, and particularly to a green production method of sulfonated para-ester. Background Art

[0002] Sulfonated para-ester, also known as 4-β-hydroxyethylsulfonic acid ester aniline-2-sulfonic acid, is an important intermediate and is widely used in fields such as dyes, pharmaceuticals, surfactants, and polymer materials. For example, in anionic surfactants, sulfonated para-ester is used as the core component of detergents and oilfield auxiliaries due to its excellent emulsifying property and biodegradability; in the pharmaceutical industry, its derivatives can be used to synthesize antibacterial agents or drug carriers.

[0003] The existing preparation of sulfonated para-ester usually uses concentrated sulfuric acid or fuming sulfuric acid as the sulfonating agent, and the sulfonation reaction is carried out in a high-temperature range of 120 - 150 °C and an organic solvent system. This process mainly has the following three problems: (1) A large amount of acidic waste liquid containing sulfates is generated after the reaction, and the treatment cost is high and it is easy to cause water body acidification. In addition, the emission of volatile organic solvents exacerbates air pollution, and the environmental pollution is serious; (2) The strong acid system has strong corrosiveness to equipment, and there are risks of leakage and explosion; (3) The sulfonation reaction is prone to sulfonation or aromatic ring cleavage, and the product selectivity is low, and multiple purifications are required, further increasing energy consumption and waste volume. It can be seen that the traditional sulfonated para-ester production process generally has problems of high pollution, high energy consumption, and low selectivity.

[0004] With the increasingly strict international environmental protection regulations and the growing demand of consumers for green products, there is an urgent need for an environmentally friendly sulfonated para-ester production process. Summary of the Invention

[0005] (I) Technical Problems to be Solved

[0006] In view of the deficiencies of the prior art, the present invention provides a green production method of sulfonated para-ester, adopting a microwave-assisted sulfonation process to solve the problems raised in the above background art.

[0007] (II) Technical Solutions

[0008] To achieve the above object, the present invention is realized through the following technical solutions:

[0009] According to the first aspect of the present invention, there is provided a green production method of sulfonated para-ester, including the following steps:

[0010] Step 1: Add ethyl p-nitrobenzoate, a sulfonating agent, and a solvent into a microwave reaction kettle for a closed reaction. After the reaction is completed, cool it to room temperature to obtain a reaction solution;

[0011] Step 2: Vacuum filter the reaction solution, and collect the filtrate and the solid catalyst separately;

[0012] Step 3: Add sodium carbonate solution to the filtrate to precipitate the sulfonated para-ester.

[0013] Preferably, in Step 1, the addition amount of the sulfonating agent is 5% - 10% of the ethyl p-nitrobenzoate;

[0014] The volume ratio of the ethyl p-nitrobenzoate to the solvent is 1:3 - 5.

[0015] Preferably, in Step 1, the sulfonating agent is selected from at least one of sulfonated resin Amberlyst-15, heteropolyacid H3PW 12 O 40 or bio-based aminosulfonic acid;

[0016] The solvent is selected from water and / or ethanol.

[0017] Preferably, in Step 1, the microwave power of the closed reaction includes a first-stage microwave power and a second-stage microwave power. The first-stage microwave power is 300 - 400W, the second-stage microwave power is 200 - 300W, and the difference between the first-stage microwave power and the second-stage microwave power is 50 - 100W.

[0018] Preferably, in Step 1, the temperature of the closed reaction is 80 - 100°C, the time is 20 - 40 min, and the stirring speed is 300 - 500 rpm.

[0019] Preferably, in Step 2, the solid catalyst is washed with deionized water and then dried, and can be recycled.

[0020] Preferably, in Step 3, add sodium carbonate solution to the filtrate to adjust the pH of the filtrate to 6 - 7.

[0021] Preferably, in Step 3, dissolve the precipitated sulfonated para-ester in ethanol and purify it by distillation.

[0022] Preferably, the parameters of the distillation are: the vacuum degree is 0.3 - 0.5 mbar, the evaporation temperature is 93 - 97°C, the condensation temperature is 20 - 30°C, and the feeding speed is 1.0 - 1.5 mL / min.

[0023] (III) Beneficial Effects

[0024] The present invention provides a green production method for sulfonated para-ester, having the following beneficial effects:

[0025] (1) The green production method for sulfonated para-ester provided by this solution adopts a microwave-assisted sulfonation process. By the action of microwaves on the reaction substances, it can heat quickly and evenly, precisely control the temperature, reduce the by-products generated by over-sulfonation, improve the selectivity of the product, shorten the reaction time, and reduce energy consumption.

[0026] (2) A green production method of sulfonated p-ester provided by this solution uses a green solvent, which can reduce the emission of VOCs, and the solvent recovery rate can reach more than 90%.

[0027] (3) A green production method of sulfonated p-ester provided by this solution uses a solid acid catalyst that can be reused after simple filtration, reducing the treatment cost of waste liquid. During the precipitation of sulfonated p-ester, the sulfate in the neutralized wastewater can be converted into gypsum for resource utilization, achieving nearly zero emissions. Detailed implementation manners

[0028] To facilitate the understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure content of the present invention more thorough and comprehensive.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments or examples and are not intended to limit the present invention.

[0030] Example 1

[0031] Add 500 g of ethyl p-nitrobenzoate, 25 g of sulfonating agent Amberlyst-15 and 2.5 L of ethanol solution to a microwave reaction for sealed reaction. Set the microwave power to 400 W within 0 - 10 min, adjust the microwave power to 300 W within 10 - 30 min. The temperature of the sealed reaction is 90 °C and the time is 30 min. Stir at a speed of 400 rpm during the reaction. After the reaction, cool to room temperature to obtain a reaction solution; vacuum filter the reaction solution to recover the catalyst, wash it with water and then dry it for recycling. Add a 5% sodium carbonate solution to the collected filtrate to adjust the pH of the filtrate to 6.5 to precipitate a solid crude product. Then dissolve the solid crude product in ethanol, control the vacuum degree to 0.3 mbar, the evaporation temperature to 95 °C, and feed at a speed of 1.2 mL / min for distillation and purification to obtain a sulfonated p-ester with a product purity of 96%.

[0032] Example 2

[0033] Add 500 g of ethyl p-nitrobenzoate, 40 g of sulfonating agent heteropolyacid H3PW 12 O 40Add 2 L of water to the microwave reaction for sealed reaction. Set the microwave power to 350 W within 0 - 15 min, adjust the microwave power to 250 W within 15 - 40 min. The temperature of the sealed reaction is 85 °C and the time is 40 min. Stir at a speed of 300 rpm during the reaction. After the reaction, cool to room temperature to obtain the reaction solution; Vacuum filter the reaction solution to recover the catalyst, wash it with water and then dry it for recycling. Add 5% sodium carbonate solution to the collected filtrate to adjust the pH of the filtrate to 6.5, precipitate the solid crude product, and then dissolve the solid crude product in ethanol. Control the vacuum degree to 0.3 mbar, the evaporation temperature to 95 °C, and feed at a speed of 1.2 mL / min for distillation purification to obtain sulfonated para-ester with a product purity of 94%.

[0034] Example 3

[0035] Add 500 g of ethyl p-nitrobenzoate, 50 g of sulfonating agent bio-based aminosulfonic acid and 1.5 L of ethanol to the microwave reaction for sealed reaction. Set the microwave power to 380 W within 0 - 12 min, adjust the microwave power to 280 W within 12 - 30 min. The temperature of the sealed reaction is 100 °C and the time is 25 min. Stir at a speed of 500 rpm during the reaction. After the reaction, cool to room temperature to obtain the reaction solution; Vacuum filter the reaction solution to recover the catalyst, wash it with water and then dry it for recycling. Add 5% sodium carbonate solution to the collected filtrate to adjust the pH of the filtrate to 6.5, precipitate the solid crude product, and then dissolve the solid crude product in ethanol. Control the vacuum degree to 0.3 mbar, the evaporation temperature to 95 °C, and feed at a speed of 1.2 mL / min for distillation purification to obtain sulfonated para-ester with a product purity of 95%.

[0036] Example 4

[0037] Add 500 g of ethyl p-nitrobenzoate, 35 g of sulfonating agent Amberlyst-15 and 3 L of ethanol solution to the microwave reaction for sealed reaction. Set the microwave power to 300 W within 0 - 10 min, adjust the microwave power to 200 W within 10 - 30 min. The temperature of the sealed reaction is 80 °C and the time is 35 min. Stir at a speed of 350 rpm during the reaction. After the reaction, cool to room temperature to obtain the reaction solution; Vacuum filter the reaction solution to recover the catalyst, wash it with water and then dry it for recycling. Add 5% sodium carbonate solution to the collected filtrate to adjust the pH of the filtrate to 6.5, precipitate the solid crude product, and then dissolve the solid crude product in ethanol. Control the vacuum degree to 0.3 mbar, the evaporation temperature to 95 °C, and feed at a speed of 1.2 mL / min for distillation purification to obtain sulfonated para-ester with a product purity of 93%.

[0038] Example 5

[0039] 500 g of ethyl p-nitrobenzoate, 25 g of sulfonating agent Amberlyst-15 and 2.5 L of ethanol solution were added to a microwave reaction for sealed reaction. The microwave power was set to 400 W within 0 - 10 min, and adjusted to 300 W within 10 - 30 min. The temperature of the sealed reaction was 90 °C and the time was 30 min. Stirring was carried out at a speed of 400 rpm during the reaction. After the reaction, it was cooled to room temperature to obtain a reaction solution; the reaction solution was vacuum filtered to recover the catalyst, washed with water and then dried for recycling. 5% sodium carbonate solution was added to the collected filtrate to adjust the pH of the filtrate to 6.5 to precipitate the solid crude product. Then the solid crude product was dissolved in ethanol, the vacuum degree was controlled at 0.3 mbar, the evaporation temperature was 97 °C, the condensation temperature was 20 °C, and feeding was carried out at a speed of 1.5 mL / min for distillation and purification to obtain sulfonated p-ester with a product purity of 98%.

[0040] For the green production method of sulfonated p-ester provided in Examples 1 to 5 of the present invention, compared with the traditional sulfuric acid sulfonation process, as shown in Table 1:

[0041] Table 1

[0042]

[0043]

[0044] According to the data in Table 1, it can be seen that the green production method of sulfonated p-ester provided by the present invention can increase the yield by 20 - 25%, reduce the energy consumption by 60% compared with the traditional sulfuric acid sulfonation process, the sulfonating agent after the reaction can be recycled, achieving zero waste acid discharge, and at the same time using non-toxic solvents water and ethanol to replace toluene and DMF to achieve green production.

[0045] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A green production method of sulfonated para-ester, characterized in that: It includes the following steps: Step 1: Add ethyl p-nitrobenzoate, a sulfonating agent, and a solvent into a microwave reactor for a sealed reaction. After the reaction is completed, cool it to room temperature to obtain a reaction solution; Step 2: Vacuum filter the reaction solution, and collect the filtrate and the solid catalyst separately; Step 3: Add a sodium carbonate solution to the filtrate to precipitate the sulfonated p-ester; 2. The green production method of a sulfonated para-ester according to claim 1, characterized in that: In Step 1, the addition amount of the sulfonating agent is 5% - 10% of the ethyl p-nitrobenzoate; The volume ratio of the ethyl p-nitrobenzoate to the solvent is 1:3 - 5.

3. A green production method of sulfonated para-ester according to claim 1, characterized in that: In Step 1, the sulfonating agent is selected from at least one of sulfonated resin Amberlyst-15, heteropolyacid H3PW 12 O 40 or bio-based aminosulfonic acid; The solvent is selected from water and / or ethanol.

4. A green production method of sulfonated para-ester according to claim 1, characterized in that: In Step 1, the microwave power of the sealed reaction includes a first-stage microwave power and a second-stage microwave power. The first-stage microwave power is 300 - 400 W, the second-stage microwave power is 200 - 300 W, and the difference between the first-stage microwave power and the second-stage microwave power is 50 - 100 W.

5. The green production method of a sulfonated para-ester according to claim 1, characterized in that: In Step 1, the temperature of the sealed reaction is 80 - 100 °C, the time is 20 - 40 min, and the stirring speed is 300 - 500 rpm.

6. The green production method of a sulfonated para-ester according to claim 1, characterized in that: In Step 2, the solid catalyst is washed with deionized water and then dried, and can be recycled.

7. A green production method of sulfonated para-ester according to claim 1, characterized in that: In Step 3, add a sodium carbonate solution to the filtrate to adjust the pH of the filtrate to 6 - 7.

8. A green production method of sulfonated para-ester according to claim 1, characterized in that: In Step 3, dissolve the precipitated sulfonated p-ester in ethanol and purify it by distillation.

9. A green production method of sulfonated para-ester according to claim 8, characterized in that: The parameters of the distillation are: the vacuum degree is 0.3 - 0.5 mbar, the evaporation temperature is 93 - 97 °C, the condensation temperature is 20 - 30 °C, and the feeding speed is 1.0 - 1.5 mL / min.

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