A method for synthesizing 2-aminoethyl hydrogen sulfate

Abstract

The application provides a 2-aminoethyl hydrogen sulfate synthesis method, first, ethanolamine and centrifugal mother liquor are mixed in a mixer by a transfusion pump according to a certain proportion, then the mixture is introduced into a first-stage tubular reactor to react, then the reaction solution is mixed with sulfuric acid, after the mixing, the mixture is introduced into a second-stage tubular reactor to react, after the reaction is completed, the reaction solution is cooled and crystallized, and 2-aminoethyl hydrogen sulfate is obtained by centrifugal drying. The application has the advantages that the solubility of 2-aminoethyl hydrogen sulfate in the reaction solution is significantly improved, the situation that a large amount of solid is precipitated in the reaction process is effectively avoided, the high reaction conversion rate is ensured, the conditions for the optimization of the crystallization process are provided, and the problems of the solid content fluctuation and the unstable crystallization state caused by the dehydration control are fundamentally solved.

Description

Technical Field

[0001] This invention relates to the field of organic synthetic chemistry technology, specifically to a method for synthesizing 2-aminoethyl hydrogen sulfate. Background Technology

[0002] 2-Aminoethyl hydrogen sulfate is an important intermediate widely used in the synthesis of ethyleneimine, taurine, and other functional compounds used in pharmaceuticals, materials, and surfactants. It is primarily obtained through the esterification reaction of monoethanolamine with sulfate. CN 104478776 reports a method of adding an aqueous sulfuric acid solution dropwise to an aqueous ethanolamine solution at 5–15 °C. After the addition is complete, the mixture is stirred for 18–25 min. The mixture is then concentrated under reduced pressure to 1 / 4 of its original volume, and the temperature is raised to 170–180 °C. The reaction continues until no water evaporates. The mixture is then reacted at 180 °C for 50–60 min and cooled to obtain crude 2-aminoethyl hydrogen sulfate. CN 113527674 reports a method involving the slow addition of concentrated sulfuric acid to ice water at 4 °C, followed by the slow addition of ethanolamine at a molar ratio of 1:1, while maintaining the reaction temperature at 5–20 °C. After the addition is complete, vacuum distillation is performed in an oil bath at an initial temperature of 135 °C. After most of the liquid is distilled off, the temperature is raised to 160 °C. Once the solution becomes turbid, heating is immediately stopped, and the solution is removed from the oil bath and allowed to cool naturally in air. A white solid precipitates out, and the process continues for several hours until the liquid becomes a completely white solid. However, the above preparation method requires complete dehydration during the heating and dehydration process until the liquid becomes a completely white solid, i.e., the reaction system is non-flowing. Therefore, this process is difficult to implement in industrial applications. Some literature reports that introducing water-removing agents, including 36% formaldehyde solution (Research on the New Synthetic Method for Preparing Taurine. Journal of Jilin Chemical Engineering Institute. 2003.9), toluene (Improvement of Taurine Synthesis Process. Journal of Chemical Industry and Engineering (China). 2015.1: 171-178), n-butanol, benzene, and cyclohexane, into the reaction system can promote conversion and ensure the fluidity of the reaction system; however, the introduction of organic solvents has brought more unfavorable factors to industrialization. CN 115368279 reports a process in which an ethanolamine sulfate solution is transferred into an esterification reactor, followed by the addition of a crystallizing agent and an ethanolamine sulfate seed slurry with a solid content of 20%-60%. Stirring is then initiated, a vacuum system is activated, and heating is performed at 85 ℃-120 ℃ for 0.5 h-2.5 h. The reaction mother liquor is then centrifuged and filtered to obtain ethanolamine sulfate crystals. This process improves the overall flowability of the final reaction solution, representing a significant step towards industrialization. However, the added crystallizing agent inevitably introduces impurities into the system, and the need to screen the ethanolamine sulfate seed crystals further increases the number of steps and costs.

[0003] Existing preparation methods typically involve the direct reaction of ethanolamine with sulfuric acid, but these methods suffer from numerous side reactions, high product impurity content, difficulty in controlling acid-base neutralization, and poor industrial applicability. Therefore, developing a simple, high-yield preparation method suitable for industrial production is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a method for synthesizing 2-aminoethyl hydrogen sulfate by increasing the reaction temperature to improve solubility, achieve effective separation of the reaction stage and the crystallization stage, improve reaction conversion rate, and reduce energy consumption.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: This invention proposes a method for synthesizing 2-aminoethyl hydrogen sulfate. First, ethanolamine and centrifuged mother liquor are mixed in a certain proportion in a mixer using a pump. Then, the mixture is introduced into a first-stage tubular reactor for reaction. Next, the above reaction solution is mixed with sulfuric acid and then introduced into a second-stage tubular reactor for reaction. After the reaction is completed, the reaction solution is cooled and crystallized, and then centrifuged and dried to obtain 2-aminoethyl hydrogen sulfate.

[0006] The specific steps are as follows: Step 1) The centrifuged mother liquor and ethanolamine are separately pumped into a mixer at a set ratio for mixing. The water content of the centrifuged mother liquor is 20%–30%, and the ethanolamine content in the centrifuged mother liquor is 1.01–1.1 times the molar amount of sulfuric acid it contains. The amount of centrifuged mother liquor used is 2–20 times the mass of ethanolamine. After mixing, the mixture is introduced into a primary tubular reactor for reaction. Subsequently, the resulting reaction solution is further mixed with sulfuric acid. The amount of sulfuric acid used is 0.90–0.99 times the molar amount of ethanolamine, and the concentration of the sulfuric acid is 90%–98%. After thorough mixing, the mixture is introduced into a secondary tubular reactor for reaction. The reaction temperature is 120–180°C, the pressure is 0–1.0 MPa, and the total reaction time is 5–300 s. Step 2) After the reaction is completed, the reaction solution is flash evaporated and then cooled and crystallized in a crystallizer. It is then centrifuged and dried to obtain 2-aminoethyl hydrogen sulfate product.

[0007] Furthermore, the amount of the centrifuged mother liquor used is 5.0 to 15 times the mass of ethanolamine.

[0008] Furthermore, the molar ratio of ethanolamine to sulfuric acid in the centrifuged mother liquor is 1.02 to 1.05.

[0009] Furthermore, the amount of sulfuric acid used, calculated as pure sulfuric acid, is 0.92 to 0.97 times the molar amount of ethanolamine.

[0010] Furthermore, the reaction temperature in the primary tubular reactor is 95–105°C.

[0011] Furthermore, the reaction temperature in the two-stage tubular reactor is 150–170°C.

[0012] Furthermore, the reaction pressure is 0.4–0.7 MPa.

[0013] Furthermore, the total reaction time is 10–30 s.

[0014] Furthermore, in step 2), after the reaction is completed, the reaction solution is clear and transparent. After removing some water by flash evaporation, it enters a crystallizer for cooling and crystallization, followed by centrifugation and drying. The mother liquor is tested for moisture, ethanolamine and sulfuric acid content, and the mother liquor is treated to meet the experimental requirements.

[0015] The formation mechanism of 2-aminoethyl hydrogen sulfate in this invention is as follows: ethanolamine is first neutralized with sulfuric acid to obtain ethanolamine sulfate, and then the ethanolamine sulfate is dehydrated to generate 2-aminoethyl hydrogen sulfate, wherein step 2) is a reversible reaction.

[0016] The yield of 2-aminoethyl hydrogen sulfate obtained by this invention is greater than 93.0%, and the product content is greater than 97.0%.

[0017] Compared with the prior art, the present invention has the following advantages: Compared to traditional preparation processes, the process of this invention increases the amount of ethanolamine fed into the mother liquor system, thereby increasing the reaction temperature without removing the generated water. This significantly improves the solubility of 2-aminoethyl hydrogen sulfate in the reaction solution, effectively avoiding the precipitation of a large amount of solid during the reaction, ensuring a high reaction conversion rate, providing conditions for optimizing the crystallization process, and fundamentally solving the problems of solid content fluctuation and unstable crystallization state caused by dehydration control. Specifically, increasing the reaction temperature helps promote the reaction in the forward direction, while increasing the amount of ethanolamine can compensate for the adverse effects of moisture on the reaction, thus achieving effective separation between the reaction stage and the crystallization stage. By introducing a mother liquor system, excess ethanolamine is retained in the mother liquor during crystallization, thereby reducing solid entrainment. The application of tubular reactors further ensures the smooth progress of the reaction under higher temperature and pressure conditions, avoiding the decrease in the solubility of 2-aminoethyl hydrogen sulfate due to excessive removal of moisture, and achieving good connection between the reaction and crystallization processes. The increase in reaction temperature significantly accelerates the reaction rate, while the introduction of two-stage tubular reactors fully utilizes the heat released by the neutralization reaction of sulfuric acid and ethanolamine, thereby significantly reducing energy consumption in the process. After centrifugation, the solid is dried to further improve the purity of the product. Attached Figure Description

[0018] Figure 1 This is a simplified diagram of the experimental apparatus and reaction sequence of the present invention. Detailed Implementation

[0019] The embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.

[0020] like Figure 1 As shown, the dimensions of the two-stage tubular reactor are: inner diameter 3 mm and total length approximately 30 m.

[0021] The product obtained by this invention was confirmed to be 2-aminoethyl hydrogen sulfate by HPLC and 1H-NMR analysis. Example 1

[0022] The water content in the mother liquor is set at 25%, and the ratio of ethanolamine to sulfuric acid in the mother liquor is 1.02:1 (molar ratio); for the first-order reaction, the ratio of mother liquor to ethanolamine is 9.5:1 (mass ratio); for the second-order reaction, the ratio of sulfuric acid to ethanolamine is 0.96:1 (molar ratio).

[0023] First, 29.5 g of ethanolamine and 280.4 g of mother liquor are mixed by two metering pumps and then fed into a primary tubular reactor. The reaction temperature is controlled at 100°C. The reaction solution is then mixed with 98% and 46.4 g of sulfuric acid by another mixer and fed into a secondary tubular reactor. The reaction temperature is 160°C, the reaction pressure is 0.7 MPa, and the residence time is 15 s.

[0024] The flow rate of the mixed reaction solution is approximately 6.3 mL / s; the total length of the tubular reactor is approximately 30 m. Therefore, the residence time of the mixed reaction solution in the tubular reactor is 15 s.

[0025] The resulting reaction solution was then transferred to a crystallization reactor, where some of the water was flash-evaporated and deposited in a condensate tank. After crystallization, the reaction solution was centrifuged and dried. The resulting product, after testing, had a purity of 98.7% and a yield of 96.2%. Example 2

[0026] The water content in the mother liquor is set at 25%, and the ratio of ethanolamine to sulfuric acid in the mother liquor is 1.02:1 (molar ratio); for the first-order reaction, the ratio of mother liquor to ethanolamine is 9.5:1 (mass ratio); for the second-order reaction, the ratio of sulfuric acid to ethanolamine is 0.96:1 (molar ratio).

[0027] First, 29.5 g of ethanolamine and 280.4 g of mother liquor were mixed via two metering pumps and then fed into a primary tubular reactor at a controlled temperature of 100°C. The reaction solution was then mixed with 98% sulfuric acid (46.4 g) via another mixer and fed into a secondary tubular reactor at a controlled temperature of 160°C, a pressure of 0.7 MPa, and a residence time of 30 s. The resulting reaction solution was then fed into a crystallization vessel, where some water was flash-evaporated and collected in a condensate tank. After crystallization, the reaction solution was centrifuged and dried. The resulting product had a purity of 98.0% and a yield of 96.6%.

[0028] Compared to Example 1, the length of the tubular reactor remains unchanged, and the flow rate of the mixed reaction liquid is adjusted accordingly to ensure that the residence time of the mixed reaction liquid in the tubular reactor is 30s. Example 3

[0029] The water content in the mother liquor is set at 25%, and the ratio of ethanolamine to sulfuric acid in the mother liquor is 1.02:1 (molar ratio); for the first-order reaction, the ratio of mother liquor to ethanolamine is 9.5:1 (mass ratio); for the second-order reaction, the ratio of sulfuric acid to ethanolamine is 0.96:1 (molar ratio).

[0030] First, 29.5 g of ethanolamine and 280.4 g of mother liquor were mixed via two metering pumps and then fed into a primary tubular reactor at a controlled temperature of 100°C. The reaction mixture was then mixed with 98% sulfuric acid (46.4 g) via another mixer and fed into a secondary tubular reactor at a controlled temperature of 160°C, a pressure of 0.7 MPa, and a residence time of 5 s. The resulting reaction mixture was then fed into a crystallization vessel, where some water was flash-evaporated and collected in a condensate tank. After crystallization, the reaction mixture was centrifuged and dried. The resulting product had a purity of 98.3% and a yield of 95.6%.

[0031] Compared to Example 1, the length of the tubular reactor remains unchanged, and the flow rate of the mixed reaction liquid is adjusted accordingly to ensure that the residence time of the mixed reaction liquid in the tubular reactor is 5 seconds.

[0032] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the concept of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for synthesizing 2-aminoethyl hydrogen sulfate, characterized in that... Includes the following steps: Step 1) The centrifuged mother liquor and ethanolamine are separately pumped into a mixer at a set ratio for mixing. The water content of the centrifuged mother liquor is 20%–30%, and the ethanolamine content in the centrifuged mother liquor is 1.01–1.1 times the molar amount of sulfuric acid it contains. The amount of centrifuged mother liquor used is 2–20 times the mass of ethanolamine. After mixing, the mixture is introduced into a primary tubular reactor for reaction. Subsequently, the resulting reaction solution is further mixed with sulfuric acid. The amount of sulfuric acid used is 0.90–0.99 times the molar amount of ethanolamine, and the concentration of the sulfuric acid is 90%–98%. After thorough mixing, the mixture is introduced into a secondary tubular reactor for reaction. The reaction temperature is 120–180°C, the pressure is 0–1.0 MPa, and the total reaction time is 5–300 s. Step 2) After the reaction is completed, the reaction solution is flash evaporated and then cooled and crystallized in a crystallizer. It is then centrifuged and dried to obtain 2-aminoethyl hydrogen sulfate product.

2. The method for synthesizing 2-aminoethyl hydrogen sulfate according to claim 1, characterized in that: The amount of the centrifuged mother liquor used is 5.0 to 15 times the mass of ethanolamine.

3. The method for synthesizing 2-aminoethyl hydrogen sulfate according to claim 1, characterized in that: The molar ratio of ethanolamine to sulfuric acid in the centrifuged mother liquor is 1.02 to 1.

05.

4. The method for synthesizing 2-aminoethyl hydrogen sulfate according to claim 1, characterized in that: The amount of sulfuric acid used, calculated as pure sulfuric acid, is 0.92 to 0.97 times the molar amount of ethanolamine.

5. The method for synthesizing 2-aminoethyl hydrogen sulfate according to claim 1, characterized in that: The reaction temperature in the primary tubular reactor is 95–105°C.

6. The method for synthesizing 2-aminoethyl hydrogen sulfate according to claim 1, characterized in that: The reaction temperature in the two-stage tubular reactor is 150–170°C.

7. The method for synthesizing 2-aminoethyl hydrogen sulfate according to claim 1, characterized in that: The reaction pressure is 0.4–0.7 MPa.

8. The method for synthesizing 2-aminoethyl hydrogen sulfate according to claim 1, characterized in that: The total reaction time is 10–30 s.

Images