A process for the preparation of hydroquinone dihydroxyethyl ether
Patent Information
- Application Number
- CN202510547444.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-28
- Publication Date
- 2026-10-30
AI Technical Summary
现有技术在合成对苯二酚二羟乙基醚的过程中存在如下问题，如反应原料危险性高、原料成本高、反应过程时间长或者操作繁琐或者后处理繁琐、反应过程生成污染环境的废水废盐、产品品质不达标等，这些问题使得对苯二酚二羟乙基醚的合成方法受限
[0009]本发明实施例提供的对苯二酚二羟乙基醚的制备方法，原料使用的碳酸乙烯酯，危险性小且成本低；使用的催化剂为固态有机化合物，整个体系无需使用溶剂，过程中无废盐、废水生成，环境污染小；对产品的后处理过程无水的引入，保证了产品的收率以及纯度。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of chemical synthesis technology, and more specifically, to a method for preparing hydroquinone dihydroxyethyl ether. Background Technology
[0002] Hydroquinone dihydroxyethyl ether (HQEE) is a structurally symmetrical solid aromatic diol, primarily used as a chain extender in polyurethanes. Existing technologies for synthesizing HQEE suffer from several problems, including high-risk reactants, high raw material costs, long reaction times, cumbersome operations or post-processing, environmentally polluting wastewater and waste salts generated during the reaction, and substandard product quality. These issues limit the available methods for synthesizing HQEE.
[0003] In view of this, the present invention is proposed. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing hydroquinone dihydroxyethyl ether to solve the above-mentioned technical problems.
[0005] This invention is implemented as follows:
[0006] In a first aspect, embodiments of the present invention provide a method for preparing hydroquinone dihydroxyethyl ether, wherein hydroquinone, ethylene carbonate and a catalyst are mixed and reacted at a reaction temperature of 100°C-200°C for a reaction time of 1h-6h.
[0007] The amount of catalyst added is 0.1wt%-4wt% of the mass of hydroquinone.
[0008] The present invention has the following beneficial effects:
[0009] The method for preparing hydroquinone dihydroxyethyl ether provided in this invention uses ethylene carbonate as a raw material, which is low in risk and cost; the catalyst used is a solid organic compound, the entire system does not require the use of solvents, and no waste salt or wastewater is generated during the process, resulting in minimal environmental pollution; and no water is introduced into the post-processing of the product, ensuring the yield and purity of the product. Attached Figure Description
[0010] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0011] Figure 1 The infrared spectrum of product HQEE prepared in Example 1;
[0012] Figure 2 The infrared spectrum of product HQEE prepared in Example 1 is compared with the spectrum in the spectrum library;
[0013] Figure 3 The mass spectrum of HQEE, the product prepared in Example 1. Detailed Implementation
[0014] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.
[0015] The traditional synthesis process of hydroquinone dihydroxyethyl ether (HQEE) uses sodium hydroxide (approximately 5 wt%) as a catalyst, requiring subsequent acid neutralization and generating a large amount of waste brine. Furthermore, HQEE is primarily used as a chain extender in polyurethane, necessitating strict control of its water content. The synthesized HQEE requires vacuum drying and molecular sieve dehydration to reduce the water content to below 0.1%. The reactant is ethylene oxide, which is flammable, explosive, carcinogenic, and toxic, posing a high risk. This invention addresses these technical problems by modifying the raw materials and the post-processing of the product.
[0016] In a first aspect, embodiments of the present invention provide a method for preparing hydroquinone dihydroxyethyl ether, wherein hydroquinone, ethylene carbonate and a catalyst are mixed and reacted at a reaction temperature of 100℃-200℃ for a reaction time of 1h-6h.
[0017] The amount of catalyst added is 0.05wt%-1wt% of the total mass of hydroquinone and ethylene carbonate.
[0018] It should be noted that the chemical equation for the preparation process of hydroquinone dihydroxyethyl ether is as follows:
[0019]
[0020] During the reaction, carbon dioxide gas is generated. To facilitate monitoring the completion of the reaction, a flow meter is installed in the reaction apparatus. The reaction ends when the gas flow rate monitored by the flow meter reaches 0. In other embodiments of the invention, a flow meter of appropriate specifications can be selected according to actual needs.
[0021] The use of catalysts has the following characteristics: they can be easily separated and recovered from the reaction mixture, reducing environmental pollution and production costs; no organic solvents are required during preparation and use, further reducing environmental pollution; in addition, they do not require neutralization or concentration in the catalytic reaction, thus avoiding secondary pollution and helping to reduce the environmental burden.
[0022] Because gas is generated during the reaction, the reaction apparatus needs to be sealed. The specific reaction apparatus is selected and set according to actual needs. In the embodiment of this invention, a four-necked flask is used. To prevent the reactants from volatilizing at high temperatures, ensure that the concentration of reactants remains constant, and improve the reaction conversion rate, a condenser is added, and a flow meter is also set to monitor the degree of reaction completion.
[0023] In an optional embodiment of the present invention, the amount of catalyst added is 0.2 wt% to 2 wt% of the mass of hydroquinone. Specifically, the amount of catalyst used can be selected from any one of 0.26 wt%, 0.33 wt%, 0.65 wt%, 1.31 wt%, and 2 wt%, or other values in the range of 0.2 wt% to 2 wt%.
[0024] In an optional embodiment of the present invention, the catalyst is selected from at least one of triphenylphosphine, 4-pyrrolylpyridine, and 4-dimethylaminopyridine.
[0025] The advantages of triphenylphosphine as a catalyst are mainly reflected in its unique chemical structure and properties. In the chemical structure of triphenylphosphine, phosphorus atoms are linked to three benzene rings, forming a stable molecular structure. This gives it high chemical and thermal stability, enabling it to maintain its catalytic activity at high temperatures and pressures.
[0026] 4-Pyrrolidinylpyridine, as a catalyst, possesses high efficiency, selectivity, and reusability. It can be easily separated and recovered after the reaction and reused in the next reaction. This reusability reduces costs and minimizes catalyst waste.
[0027] 4-Dimethylaminopyridine, as a catalyst, also has the characteristics of high efficiency, selectivity and reusability. It can be easily separated and recovered after the reaction is completed and then reused in the next reaction.
[0028] It should be noted that changing the type of catalyst can have a significant impact on the product yield.
[0029] In an optional embodiment of the present invention, the molar ratio of hydroquinone to ethylene carbonate is 1:(1.9-2.1).
[0030] It should be noted that the setting of the molar ratio of the reaction raw materials is closely related to the structural formulas of hydroquinone and ethylene carbonate. In the specific reaction process, it is advisable to set one of the substances in slightly more quantity, which is beneficial to the forward reaction and the complete reaction of the raw materials.
[0031] In an optional embodiment of the present invention, the reaction temperature is 120℃-170℃; more specifically, it is 135℃-170℃. Specifically, any one of 135℃, 138℃, 145℃, 160℃, 165℃, 168℃, and 170℃, or other values within the range of 135℃-170℃, can be selected.
[0032] In an optional embodiment of the present invention, the reaction time is 1h-6h; more specifically, it is 1h-4.5h. Any one of 1h, 2h, 2.5h, 3h, 3.5h, 4h, and 4.5h, or other values within the range of 1h-4.5h, can be selected.
[0033] In an optional embodiment of the present invention, after the reaction is completed, the product is further subjected to post-processing; further, the post-processing is to perform vacuum distillation on the product at a pressure of -0.096 MPa to -0.01 MPa.
[0034] It should be noted that vacuum distillation, by reducing the pressure within the system, can significantly lower the boiling point of substances, allowing them to distill at lower temperatures and thus protecting heat-sensitive substances from degradation. Operating at lower temperatures also saves energy required for heating. Furthermore, vacuum distillation can improve the efficiency and purity of separation.
[0035] In an optional embodiment of the present invention, the fraction at 260°C-268°C is collected during the distillation process.
[0036] In an optional embodiment of the present invention, the yield of hydroquinone dihydroxyethyl ether is greater than 94% and the purity is greater than 99%.
[0037] It should be noted that the method of gas chromatography determination of products and fractions in the embodiments of the present invention is not particularly limited, and conventional technical means in the art are used.
[0038] In other embodiments of the present invention, the method for purifying HQEE involves water washing, specifically as follows: 288 mL of deionized water is added to the reaction product, and the temperature is raised to 90°C to completely dissolve it. The mixture is continuously stirred until the temperature drops to 55°C-60°C until a large amount of material precipitates out. Then, the temperature is slowly lowered to 20°C-25°C, and the mixture is stirred for 2 hours. Afterward, the temperature is lowered to 6°C using chilled brine, and the mixture is stirred for another 2 hours. The mixture is then filtered and washed to obtain a filter cake, which is then vacuum dried to remove water. The final product is a powdery white solid.
[0039] The features and performance of the present invention will be further described in detail below with reference to embodiments.
[0040] Example 1
[0041] This embodiment provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), as detailed below:
[0042] Add 55g hydroquinone and 89g ethylene carbonate to a four-necked flask (250mL). Add 0.36g triphenylphosphine (0.65wt%) as catalyst. Install a condenser to prevent loss of reactants. Attach a flow meter to the top outlet of the condenser to observe the flow rate of CO2 gas generated during the reaction. Set the reaction temperature to 168℃ and the reaction time to 3h. The reaction is considered complete when the flow meter reading reaches 0 and no more gas is generated within 15min. Determine the product composition using gas chromatography. The HQEE yield is recorded in Table 1.
[0043] Remove the condenser, attach a distillation column to a four-necked flask, and perform vacuum distillation on the product. Collect the fraction between 260℃ and 268℃ at -0.096 MPa. The final product is a white solid. Weigh the product and determine its composition using gas chromatography. The HQEE purity is recorded in Table 1.
[0044] Example 2
[0045] This embodiment provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in that:
[0046] The catalyst was 0.72 g of triphenylphosphine (1.31 wt%); the reaction time was 2.5 h.
[0047] Example 3
[0048] This embodiment provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in that:
[0049] The catalyst was 0.18 g of triphenylphosphine (0.33 wt%); the reaction time was 4.5 h.
[0050] Example 4
[0051] This embodiment provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in that:
[0052] The catalyst was 0.36 g of 4-pyrrolidinylpyridine (0.65 wt%); the reaction time was 1.0 h.
[0053] Example 5
[0054] This embodiment provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in that:
[0055] The catalyst was 0.18 g of 4-pyrrolidinylpyridine (0.33 wt%); the reaction temperature was 138 °C and the reaction time was 2.0 h.
[0056] Example 6
[0057] This embodiment provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in that:
[0058] The catalyst was 0.144 g of 4-pyrrolidinylpyridine (0.26 wt%); the reaction temperature was 138 °C and the reaction time was 3.5 h.
[0059] Example 7
[0060] This embodiment provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in that:
[0061] The catalyst was 0.36 g of 4-dimethylaminopyridine (0.65 wt%); the reaction time was 1.5 h.
[0062] Comparative Example 1
[0063] This comparative example provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in that:
[0064] A 500 mL high-pressure reactor was evacuated and purged with nitrogen to atmospheric pressure, then depressurized. This process was repeated twice to replace the air in the reactor. 120 g of water, 55 g (0.5 mol) of hydroquinone, and 2 g (3.6 wt%) of sodium hydroxide catalyst were added to the reactor. The reactor was heated and stirred to ensure the hydroquinone and catalyst were fully dissolved in the water (the pH of the solution was 11 at this point). When the temperature reached 60 °C, 48.5 g (0.55 mol) of ethylene oxide was introduced. The rate of ethylene oxide introduction and the amount of circulating cooling water were controlled to maintain the reaction temperature at 90 °C and the pressure at 0.6 MPa. After reacting under pressure for 8 hours, the temperature was cooled to 60 °C. The solution was transferred to 100 g of diluted 0.5 mol / L hydrochloric acid solution to neutralize the sodium hydroxide catalyst used in the reaction. After stirring thoroughly for 30 minutes, the pH was measured to be 5.8. The temperature was further reduced to 15 °C and the solution was filtered. The HQEE yield was recorded in Table 1.
[0065] Comparative Example 2
[0066] This comparative example provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Comparative Example 1 only in that:
[0067] The catalyst was 0.36 g of triphenylphosphine (0.65 wt%); the reaction was terminated after 8 hours of pressure holding.
[0068] Comparative Example 3
[0069] This comparative example provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in that:
[0070] The catalyst was 2g of sodium hydroxide (3.6wt%); the reaction temperature was 168℃ and the reaction time was 4h.
[0071] Comparative Example 4
[0072] This comparative example provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in that:
[0073] The catalyst was 1.8 g of triphenylphosphine (3.3 wt%); the reaction temperature was 168 °C and the reaction time was 80 min.
[0074] Comparative Example 5
[0075] This comparative example provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in that:
[0076] The catalyst was 0.06 g of triphenylphosphine (0.1 wt%); the reaction temperature was 168 °C; and the reaction time was 7 h.
[0077] Comparative Example 6
[0078] This comparative example provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in that:
[0079] The catalyst was 0.36 g of triphenylphosphine (0.65 wt%); the reaction temperature was 90 °C, the reaction was extremely slow, and almost no gas was generated.
[0080] Comparative Example 7
[0081] This comparative example provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in that:
[0082] The catalyst was 0.18 g of 4-pyrrolidinylpyridine (0.33 wt%); the reaction temperature was 90 °C, the reaction was relatively slow, and the gas generation was intermittent. The yield of HQEE was determined after 12 h.
[0083] Comparative Example 8
[0084] This comparative example provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in the purification method for the HQEE product:
[0085] In this comparative example, the HQEE purification method used was water washing, specifically as follows: 288 mL of deionized water was added to the reaction product, and the temperature was raised to 90°C to completely dissolve it. The mixture was continuously stirred until the temperature dropped to 55°C-60°C until a large amount of material precipitated. Then, the temperature was slowly lowered to 20°C-25°C, and the mixture was stirred for 2 hours. Afterward, the temperature was lowered to 6°C using chilled brine, and the mixture was stirred for another 2 hours. The mixture was then filtered and washed to obtain a filter cake, which was then vacuum dried to remove water. The final product was a powdery white solid with an HQEE purity of 99.3%.
[0086] Comparative Example 9
[0087] This comparative example provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in that:
[0088] The catalyst was 0.36 g tetramethylguanidine (0.65 wt%); the reaction was extremely slow and almost no gas was generated.
[0089] Comparative Example 10
[0090] This comparative example provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in that:
[0091] The catalyst was 0.36 g of tributylphosphine (0.65 wt%); the reaction temperature was 168 °C; the reaction time was 2 h; and no gas was generated after 2 h.
[0092] Comparative Example 11
[0093] This comparative example provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in that:
[0094] The catalyst was 0.36 g diphenylphosphine (0.65 wt%); the reaction temperature was 168 °C, the reaction was slow, and no gas was generated after 1.5 h.
[0095] Comparative Example 12
[0096] This comparative example provides a method for preparing hydroquinone dihydroxyethyl ether (HQEE), which differs from Example 1 only in that:
[0097] The catalyst was 0.36 g pyridine (0.65 wt%); the reaction temperature was 168 °C; and the reaction time was 4 h.
[0098] Experimental Example 1
[0099] This experiment tested the yield and purity of HQEE prepared in Examples 1-7 and Comparative Examples 1-12. The purity was determined using gas chromatography, and the yield was calculated using the following formula:
[0100]
[0101] The relevant results are summarized in Table 1.
[0102] Table 1. Yield and purity data for HQEE
[0103]
[0104]
[0105] Note: "-" in the table indicates that the product of this example was not purified and the purity of the corresponding product was not tested.
[0106] As can be seen from the results in Table 1, the preparation method of hydroquinone dihydroxyethyl ether (HQEE) provided in this embodiment of the invention, by changing at least one of the following influencing factors, such as the type and amount of catalyst, reaction temperature, reaction time, and post-treatment method, will affect the product quality, yield, or purity of the final product HQEE. Specifically, increasing the catalyst content will shorten the reaction time, which has a relatively small impact on product purity, but the product yield will initially increase and then decrease. If the catalyst amount, reaction temperature, and reaction time are not within the set range, they will have a significant impact on the product yield. The product post-treatment method has a certain impact on product purity, and the introduction of water will also affect product quality.
[0107] Therefore, by controlling the balance of catalyst dosage, reaction temperature, and reaction time, and using a distillation purification process, the embodiments of the present invention can obtain qualified HQEE products with high yield.
[0108] Experimental Example 2
[0109] In this experiment, Fourier transform infrared spectroscopy was used to analyze the molecular structure and chemical composition of hydroquinone dihydroxyethyl ether (HQEE) prepared in Example 1. The relevant results are shown in [link to relevant documentation]. Figure 1 The infrared spectrum of the obtained HQEE was compared with the spectra in the spectral library. The comparison results are shown in [link to comparison]. Figure 2 .
[0110] Combination Figure 1 and Figure 2 The results show that the functional group peaks displayed in the spectrum match those of hydroquinone dihydroxyethyl ether (HQEE), and the matching degree with the HQEE standard spectrum in the spectrum library is high. Therefore, it is determined that the substance synthesized in the experiment is hydroquinone dihydroxyethyl ether (HQEE) with high purity.
[0111] Experimental Example 3
[0112] In this experiment, an Agilent gas chromatograph-mass spectrometer was used to analyze the hydroquinone dihydroxyethyl ether (HQEE) prepared in Example 1. The relevant results are shown in [link to results]. Figure 3 .
[0113] from Figure 3 As can be seen, by comparing the spectra of hydroquinone dihydroxyethyl ether (HQEE) standard samples in the mass spectrometry library, the two are basically consistent, so the obtained product is determined to be HQEE.
[0114] In summary, the method for preparing hydroquinone dihydroxyethyl ether (HQEE) provided in this embodiment of the invention produces high-quality HQEE, all of which is white; the raw material used, ethylene carbonate, is low in risk and cost; a solid organic compound is used as a catalyst, eliminating the need for solvents; the entire system generates no waste salts or wastewater, resulting in minimal environmental pollution; and the post-processing of the product employs vacuum distillation, ensuring the yield and purity of the product by eliminating the introduction of water during the process.
[0115] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for preparing hydroquinone dihydroxyethyl ether, characterized in that, Hydroquinone, ethylene carbonate and catalyst are mixed and reacted at a temperature of 100℃-200℃ for 1h-6h. The amount of catalyst added is 0.1wt%-4wt% of the mass of hydroquinone.
2. The preparation method according to claim 1, characterized in that, The amount of catalyst added is 0.2wt%-2wt% of the mass of hydroquinone.
3. The preparation method according to claim 1, characterized in that, The catalyst is selected from at least one of triphenylphosphine, 4-pyrrolylpyridine, and 4-dimethylaminopyridine.
4. The preparation method according to claim 1, characterized in that, The molar ratio of hydroquinone to ethylene carbonate is 1:(1.9-2.1).
5. The preparation method according to claim 1, characterized in that, The reaction temperature is 120℃-170℃; The preferred temperature is 135℃-170℃.
6. The preparation method according to claim 1, characterized in that, The reaction time is 1-6 hours. The preferred time is 1h-4.5h.
7. The preparation method according to claim 1, characterized in that, After the reaction is complete, post-processing of the product is also included; Preferably, the post-processing is to perform vacuum distillation on the product at a pressure of -0.096 MPa to -0.01 MPa.
8. The preparation method according to claim 7, characterized in that, The fraction at 260℃-268℃ is collected during the distillation process.
9. The preparation method according to claim 1, characterized in that, The apparatus for the preparation method is equipped with a flow meter to monitor the flow rate of the gas generated during the reaction.
10. The preparation method according to claim 1, characterized in that, The yield of the hydroquinone dihydroxyethyl ether is greater than 94%, and the purity is greater than 99%.