Synthesis method of hydroquinone dihydroxyethyl ether

Abstract

The invention relates to a synthesis method of hydroquinone dihydroxyethyl ether, which comprises the following steps: S1, in the absence of a solvent, enabling hydroquinone and ethylene carbonate to react in the presence of a catalyst at the temperature of 110-170 DEG C to obtain a reaction mixture; s2, cooling the reaction mixture to 60-90 DEG C, and adding a reducing agent for treatment to obtain a reaction crude product; and S3, carrying out refining treatment on the reaction crude product to obtain refined hydroquinone dihydroxyethyl ether. The synthetic method of the hydroquinone dihydroxyethyl ether, provided by the invention, is simple in process route, few in by-products, green and environment-friendly, and suitable for industrial production.

Description

Technical Field

[0001] The present application relates to a method for synthesizing hydroquinone dihydroxyethyl ether (HQEE). Background Art

[0002] There are two major types of crosslinking agents for polyurethane: "hydroxyl" and "amine". "Amine" compounds cannot be used in combination with MDI (diphenylmethane diisocyanate). "Hydroxy" compounds can be used as crosslinking agents for MDI to obtain polyurethane polymer materials that meet performance requirements. Hydroquinone dihydroxyethyl ether (HQEE) is widely used as a crosslinking agent in the synthesis of polyurethane polymer materials. It has good compatibility with MDI and can improve the strength, heat resistance, resilience and other performance indicators of polyurethane materials.

[0003] There are three main synthetic routes for hydroquinone dihydroxyethyl ether (HQEE):

[0004] 1. Chloroethanol method: Hydroquinone first reacts with sodium hydroxide to form sodium salt, and then reacts with chloroethanol to prepare HQEE. This route has a low yield and a long time to prepare HQEE. Chloroethanol is expensive, resulting in high raw material costs, and will produce chlorine-containing wastewater, which has a heavy environmental burden. This route has basically no industrial value.

[0005] 2. Ethylene oxide (EO) method: Ethylene oxide and hydroquinone are reacted in the presence of a catalyst to prepare HQEE. However, the introduction of ethylene oxide in this route increases the risk, the reaction time is relatively long, and the subsequent treatment process is relatively cumbersome.

[0006] 3. Ethylene carbonate (EC) method: Hydroquinone and ethylene carbonate react under the action of a catalyst to prepare HQEE. For example, Japanese patent JP2011148886 reported that HQEE was prepared by the reaction of hydroquinone and ethylene carbonate under the catalysis of potassium carbonate and using N,N-dimethylformamide (DMF) as a reaction solvent. This route needs to be carried out in the presence of solvent DMF, pollutes the environment during post-processing, and has high production costs. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention provides a method for synthesizing hydroquinone dihydroxyethyl ether which has the advantages of safe operation, simple process route, few by-products, environmental protection and suitability for industrial production.

[0008] The present application provides a method for synthesizing hydroquinone dihydroxyethyl ether, comprising the following steps:

[0009] S1. In the absence of a solvent, hydroquinone and ethylene carbonate are reacted in the presence of a catalyst at a temperature of 110 to 170 ° C to obtain a reaction mixture;

[0010] S2. The reaction mixture is cooled to 60-90°C, and a reducing agent is added to obtain a crude reaction product;

[0011] S3. The crude reaction product is purified to obtain purified hydroquinone dihydroxyethyl ether.

[0012] In one embodiment, the molar ratio of hydroquinone to ethylene carbonate is 1:2 to 2.15.

[0013] In one embodiment, the catalyst is one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, potassium fluoride, tetramethylammonium chloride, and tetraethylammonium bromide; and the amount of the catalyst added is 1 to 5% of the mass of hydroquinone.

[0014] In one embodiment, the reaction time of S1 is controlled within 2 to 6 hours.

[0015] In one embodiment, the reducing agent is one of sodium sulfite, sodium pyrosulfite, sodium bisulfite, and sodium dithionite.

[0016] In one embodiment, the refining process of S3 includes:

[0017] S31. washing the crude reaction product with a first solvent, filtering, and obtaining a wet cake;

[0018] S32: washing the wet cake with a second solvent, filtering and drying to obtain refined hydroquinone dihydroxyethyl ether.

[0019] In one embodiment, the first solvent is selected from one or a combination of sodium hydroxide solution, potassium hydroxide solution, acetone, methanol, isopropanol, and ethyl acetate.

[0020] In one embodiment, the second solvent is a combination of water and an organic solvent, and the organic solvent is selected from one or more of acetone, methanol, isopropanol, and ethyl acetate; preferably, the mass ratio of water to the organic solvent in the second solvent is 1:9 to 9:1, especially 1:4 to 4:1.

[0021] In one embodiment, the first solvent is the filtrate obtained from step S31; and / or

[0022] The second solvent is the filtrate obtained from step S32.

[0023] In one embodiment, the drying method is vacuum drying, the vacuum pressure is ≤-0.1MPa, and the temperature is 80-90°C.

[0024] The present application provides a method for synthesizing hydroquinone dihydroxyethyl ether, which has a simple process route, few by-products, is green and environmentally friendly, and is suitable for industrial production. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below through examples. Through these examples, the features and advantages of the present invention will become clearer and more specific.

[0026] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0027] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0028] The present application provides a method for synthesizing hydroquinone dihydroxyethyl ether, comprising the following steps:

[0029] S1. In the absence of a solvent, hydroquinone and ethylene carbonate are reacted in the presence of a catalyst at a temperature of 110 to 170 ° C to obtain a reaction mixture;

[0030] S2. The reaction mixture is cooled to 60-90°C, and a reducing agent is added to obtain a crude reaction product;

[0031] S3. The crude reaction product is purified to obtain purified hydroquinone dihydroxyethyl ether.

[0032] In order to avoid undesirable side reactions, S1 is carried out under an inert atmosphere such as a nitrogen protective atmosphere. The synthesis method provided by the present invention uses ethylene carbonate as a reaction raw material, does not need to use ethylene oxide, and the reaction is carried out at normal pressure, the reaction is safe, and the process operation is simple, the synthesis line is short, and it is easy to industrialize. In the method of the present application, no additional solvent is added during the synthesis reaction process, ethylene carbonate can be used as both a reaction raw material and a reaction solvent, and the obtained product has a high purity. The inventors of the present application have found that in the absence of a solvent, hydroquinone and ethylene carbonate are reacted at a temperature of 110 to 170° C. in the presence of a catalyst, which can simplify the post-processing steps, and the post-processing process can omit the steps of removing the reaction solvent and recovering the reaction solvent; the reaction raw material conversion rate is high, the product purity is high, the yield is high, and the color is good; the reaction can be carried out at normal pressure and is not dangerous, the process is reasonable, and it is easy to industrialize.

[0033] In one embodiment, in step S1, the molar ratio of hydroquinone to ethylene carbonate is 1:2 to 2.15. In step S1, the catalyst is one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, potassium fluoride, tetramethylammonium chloride, and tetraethylammonium bromide; the catalyst feed amount is 1 to 5% of the mass of hydroquinone. In one embodiment, the reaction time of S1 is controlled at 2 to 6 hours.

[0034] After the reaction in step S1 is completed, the reaction mixture can be cooled to 60-90° C. and treated with a reducing agent to obtain a crude reaction product. In one embodiment, the reducing agent is one of sodium sulfite, sodium pyrosulfite, sodium bisulfite, and sodium dithionite. The applicant has found that adding a reducing agent can reduce the color of the product and obtain a white product.

[0035] After that, the refining process is carried out. The refining process of S3 includes:

[0036] S31. washing the crude reaction product with a first solvent, filtering, and obtaining a wet cake;

[0037] S32. Wash the wet cake with a second solvent, filter and dry to obtain refined hydroquinone dihydroxyethyl ether.

[0038] In one embodiment, the first solvent is selected from one or a combination of sodium hydroxide solution, potassium hydroxide solution, acetone, methanol, isopropanol, and ethyl acetate;

[0039] The second solvent is a combination of water and an organic solvent, and the organic solvent is selected from one or more of acetone, methanol, isopropanol, and ethyl acetate. The second solvent is refined using this water mixed solvent system, which can improve the purity and yield of the product, and has significant advantages over single-phase solvents. In one embodiment, the mass ratio of water to organic solvent in the second solvent is 1:9 to 9:1, preferably 1:4 to 4:1. The inventors found that when the mass ratio of water to organic solvent in the second solvent is lower than 1:9 and higher than 9:1, a product with a purity higher than 99% cannot be obtained.

[0040] During the refining process, the filtrate can be filtered and collected, and can be applied to the next refining treatment respectively, which does not affect the product quality after application, and can also improve the product yield. Therefore, in one embodiment, the filtrate obtained in step S31 can be used as the first solvent in step 31 of the next refining treatment, that is, the first solvent can be the filtrate obtained from step S31. Similarly, the filtrate obtained in step S32 can be used as the second solvent in step 32 of the next refining treatment, that is, the second solvent can be the filtrate obtained from step S32. In this way, there is no need to recycle the solvent used in the refining process, and the filtrate can be directly recycled for the subsequent refining process, avoiding the solvent recovery treatment step, and can save energy. The above-mentioned refining process of hydroquinone dihydroxyethyl ether of the present invention does not produce waste liquid, and the suction filtrate collected in the refining process can be recycled, and the recycling does not affect the product quality, and can also improve the product yield.

[0041] In one embodiment, the drying method is vacuum drying, the vacuum pressure is ≤-0.1MPa, and the temperature is 80-90°C.

[0042] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited to the following specific embodiments.

[0043] Example 1

[0044] Under nitrogen protection, 55g of hydroquinone, 92.4g of ethylene carbonate (molar ratio 1:2.1) and 1.47g of sodium carbonate were added to the reactor in sequence, stirred at 150°C for 4h, cooled to 60-90°C and added with sodium sulfite, and then 50g of methanol, the first solvent, was added, cooled at 20°C and desolventized to obtain a wet cake. The wet cake was transferred to the reactor, and a second solvent, 400g of water and isopropanol mixed solution (the mass ratio of isopropanol to water was 1:1) was added, stirred and washed at 20°C, and vacuum dried at 85°C after desolventization to obtain a white solid, with a purity of 99.36% and a yield of 88.5% detected by GC, a melting point of 104.5°C, and a hydroxyl value of 561mgKOH / g.

[0045] Example 2

[0046] The same as Example 1, except that 55 g of hydroquinone, 90.2 g of ethylene carbonate (molar ratio 1:2.05) and 1.47 g of sodium carbonate were added in sequence to obtain a white solid with a purity of 99.24% by GC, a yield of 86.8%, a melting point of 104.1°C, and a hydroxyl value of 565 mgKOH / g.

[0047] Example 3

[0048] The implementation method is the same as that of Example 1, except that 55 g of hydroquinone and 94.6 g of ethylene carbonate (molar ratio 1:2.15) are added in sequence to obtain a white solid with a purity of 99.08% detected by GC, a yield of 86.5%, a melting point of 105.2°C, and a hydroxyl value of 558 mgKOH / g.

[0049] Example 4

[0050] The implementation method is the same as that of Example 1, except that the amount of sodium carbonate used is 0.882 g, and a white solid is obtained. The purity detected by GC is 99.18%, the yield is 85.6%, the melting point is 103.8°C, and the hydroxyl value is 562 mgKOH / g.

[0051] Example 5

[0052] The implementation method is the same as that of Example 1, except that the reaction is carried out at 140° C. for 4 hours to obtain a white solid with a purity of 99.34% as determined by GC, a yield of 86.5%, a melting point of 104.4° C., and a hydroxyl value of 559 mgKOH / g.

[0053] Example 6

[0054] The implementation method is the same as that of Example 1, except that the reaction is carried out at 150° C. for 5 h to obtain a white solid with a purity of 99.29% as determined by GC, a yield of 88.6%, a melting point of 104.1° C., and a hydroxyl value of 562 mgKOH / g.

[0055] Example 7

[0056] The implementation method is the same as that of Example 1, except that the first solvent in the refining process is 50g acetone, and a white solid is obtained. The purity detected by GC is 99.15%, the yield is 87.5%, the melting point is 104.0°C, and the hydroxyl value is 562mgKOH / g.

[0057] Example 8

[0058] The implementation method is the same as that of Example 1, except that the second solvent in the refining process is a mixed solution of 400g water and isopropanol (the mass ratio of isopropanol to water is 4:1), and a white solid is obtained. The purity detected by GC is 99.27%, the yield is 87.9%, the melting point is 104.2°C, and the hydroxyl value is 560mgKOH / g.

[0059] Example 9

[0060] The implementation method is the same as that of Example 1, except that the second solvent in the refining process is a mixed solution of 400 g of water and ethyl acetate (the mass ratio of ethyl acetate to water is 1:4), and a white solid is obtained. The purity detected by GC is 99.32%, the yield is 87.1%, the melting point is 104.1°C, and the hydroxyl value is 561 mgKOH / g.

[0061] Example 10

[0062] The implementation method is the same as that of Example 1, except that the first solvent and the second solvent in the refining process are respectively applied to the filtrate treated with the first solvent and the second solvent collected in Example 1 to obtain a white solid with a purity of 99.25% detected by GC, a yield of 92.3%, a melting point of 104.3°C, and a hydroxyl value of 555 mgKOH / g.

[0063] Comparative Example 1

[0064] The implementation method is the same as that of Example 1, except that sodium sulfite is replaced by pure water to obtain a light brown solid with a purity of 99.27% ​​detected by GC, a yield of 88.2%, a melting point of 104.3° C., and a hydroxyl value of 560 mgKOH / g.

[0065] Comparative Example 2

[0066] The implementation method is the same as that of Example 1, except that N,N-dimethylformamide is added during the synthesis process to obtain a white solid with a purity of 97.78% detected by GC, a yield of 85.2%, a melting point of 105.2° C., and a hydroxyl value of 550 mgKOH / g.

[0067] Comparative Example 3

[0068] The implementation method is the same as that of Example 1, except that the second solvent in the refining process is a mixed solution of 400g water and isopropanol (the mass ratio of isopropanol to water is 1:15), and a white solid is obtained. The purity detected by GC is 98.25%, the yield is 85.5%, the melting point is 105.3°C, and the hydroxyl value is 546mgKOH / g.

[0069] Comparative Example 4

[0070] The implementation method is the same as that of Example 1, except that the second solvent in the refining process is 400g isopropanol, and a white solid is obtained. The purity detected by GC is 98.37%, the yield is 84.6%, the melting point is 105.1°C, and the hydroxyl value is 548mgKOH / g.

[0071] Comparative Example 5

[0072] The implementation method is the same as that of Example 1, except that the second solvent in the refining process is 400g of water, and a white solid is obtained. The purity detected by GC is 98.12%, the yield is 84.1%, the melting point is 105.3°C, and the hydroxyl value is 545mgKOH / g.

[0073] The present application has been described above in conjunction with preferred embodiments, but these embodiments are only exemplary and serve only as an illustration. On this basis, various replacements and improvements may be made to the present application, all of which fall within the scope of protection of the present application.

Claims

1. A method for synthesizing hydroquinone dihydroxyethyl ether, comprising the following steps: S1. In the absence of a solvent, hydroquinone and ethylene carbonate are reacted in the presence of a catalyst at a temperature of 110 to 170 ° C to obtain a reaction mixture; S2. The reaction mixture is cooled to 60-90°C, and a reducing agent is added to obtain a crude reaction product; S3. The crude reaction product is purified to obtain purified hydroquinone dihydroxyethyl ether.

2. The synthesis method according to claim 1, wherein The molar ratio of hydroquinone to ethylene carbonate is 1:2-2.

15.

3. The synthesis method according to claim 1, wherein The catalyst is one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, potassium fluoride, tetramethylammonium chloride and tetraethylammonium bromide; the catalyst feed amount is 1-5% of the mass of hydroquinone.

4. The synthesis method according to claim 1, wherein The reaction time of S1 is controlled within 2 to 6 hours.

5. The synthesis method according to claim 1, wherein The reducing agent is one of sodium sulfite, sodium pyrosulfite, sodium bisulfite and sodium dithionite.

6. The synthesis method according to claim 1, wherein S3 refining process includes: S31. washing the crude reaction product with a first solvent, filtering, and obtaining a wet cake; S32. Wash the wet cake with a second solvent, filter and dry to obtain refined hydroquinone dihydroxyethyl ether.

7. The synthesis method according to claim 6, wherein The first solvent is selected from one or a combination of sodium hydroxide solution, potassium hydroxide solution, acetone, methanol, isopropanol, and ethyl acetate.

8. The synthesis method according to claim 6, wherein The second solvent is a combination of water and an organic solvent, and the organic solvent is selected from one or more of acetone, methanol, isopropanol, and ethyl acetate; preferably, the mass ratio of water to the organic solvent in the second solvent is 1:9 to 9:1, especially 1:4 to 4:

1.

9. The synthesis method according to claim 6, wherein The first solvent is the filtrate obtained from step S31; and / or The second solvent is the filtrate obtained from step S32.

10. The synthesis method according to claim 6, wherein The drying method is vacuum drying, the vacuum pressure is ≤-0.1MPa, and the temperature is 80~90℃.