A method for synthesizing decabromodiphenylethane

Abstract

The present invention provides a method for synthesizing decabromodiphenylethane, belonging to the technical field of brominated flame retardant synthesis. The method uses benzyl chloride as a reaction raw material and bromine chloride as a brominating agent to synthesize decabromodiphenylethane via a one-pot, two-step process. The metal chloride produced in the first step serves as a catalyst in the second step, and the diphenylethane produced in the first step can be directly subjected to a bromination reaction without isolation. The decabromodiphenylethane synthesis method of the present invention has the advantages of simple process, high efficiency, and high product yield.

Description

Technical Field

[0001] The invention belongs to the technical field of synthesis of brominated flame retardants, and particularly relates to a method for synthesizing decabromodiphenylethane. Background Art

[0002] Decabromodiphenyl ether is a widely used new brominated flame retardant with good thermal stability, excellent fire resistance and UV resistance. It has no ether bonds in its molecular structure and will not produce carcinogenic substances such as PBDD and PBDF under high temperature conditions. It has gradually replaced decabromodiphenyl ether and become a new broad-spectrum flame retardant widely used in the market.

[0003] The existing methods for preparing decabromodiphenylethane all use 1,2-diphenylethane as the raw material, and prepare decabromodiphenylethane through the solvent method or the excess bromine method. Currently, the general industry mostly uses the excess bromine method, which heats 1,2-diphenylethane to a molten state and adds excess bromine to produce the decabromodiphenylethane product. However, this method also has problems such as pipe blockage, yellow product color, and high free bromine content. Regardless of which method is used, 1,2-diphenylethane is required as the raw material, and the synthesis, separation and purification processes of 1,2-diphenylethane are relatively complex, resulting in a high production cost for decabromodiphenylethane using 1,2-diphenylethane as the raw material.

[0004] Chinese patent publication number CN101643387A discloses a method for producing low-free-bromine decabromodiphenylethane. Through secondary distillation and ball milling, the free bromine content of the product is reduced, resulting in a high-whiteness decabromodiphenylethane product. However, the patented process is complex, and the secondary distillation consumes a lot of energy, making large-scale industrial production difficult.

[0005] Chinese patent publication number CN114213210 A discloses a method for preparing decabromodiphenylethane. By preparing a supported catalyst, the whiteness and yield of decabromodiphenylethane are improved. However, the catalyst preparation in this patent is complex and lacks catalyst recycling, resulting in high production costs and hindering industrial production. Summary of the Invention

[0006] The present invention aims to provide a method for synthesizing decabromodiphenylethane. The method uses benzyl chloride as a raw material and bromine chloride as a brominating agent to achieve the synthesis of decabromodiphenylethane through a one-pot two-step process. The method has the advantages of simple process, mild reaction conditions, high yield, and is conducive to industrial production.

[0007] To achieve the purpose of the present invention, a technical solution for a method for synthesizing decabromodiphenylethane is provided, and the specific steps are as follows:

[0008] (1) Mix cuprous chloride, reducing metal powder and nitrobenzene and heat to 50-70°C, add benzyl chloride dropwise for 0.5-1 hour, and keep warm for 4-7 hours to obtain reaction material A;

[0009] (2) Cooling the reaction material A obtained in step (1) to 0-10°C, adding bromine chloride dropwise thereto for 1-2 hours, heating the reaction to 20-40°C, and keeping the temperature for 3-6 hours to obtain reaction material B;

[0010] (3) A sodium sulfite aqueous solution is added to the reaction material B prepared in step (2) for neutralization until the color of the reaction solution changes from reddish brown to colorless, and then a sodium bicarbonate aqueous solution is added for neutralization until the pH value of the reaction solution reaches 7 to 8. The reaction solution is then filtered, washed, and dried to obtain decabromodiphenylethane.

[0011] The chemical reaction process in the above steps is as follows:

[0012]

[0013] Preferably, in step (1), the reducing metal powder is zinc powder or iron powder, the molar ratio of the metal powder to benzyl chloride is 0.6 to 1:1; the molar ratio of cuprous chloride to benzyl chloride is 2 to 10:100; and the molar ratio of nitrobenzene to benzyl chloride is 10 to 20:1.

[0014] Preferably, in step (2), the molar ratio of bromine chloride to benzyl chloride is 6 to 8:1.

[0015] Preferably, in step (3), the washing is first with concentrated hydrochloric acid, then with hot water, and finally with acetonitrile; the drying temperature is 120-160° C., and the drying time is 8-24 h.

[0016] The beneficial effects of the present invention are:

[0017] The method of the present invention realizes the preparation of decabromodiphenylethane through a one-pot two-step process, avoids the separation and purification of the intermediate product 1,2-diphenylethane, simplifies the operation steps, avoids the material consumption and energy consumption of 1,2-diphenylethane separation, and simultaneously utilizes the metal chloride generated in the first step reaction as a catalyst for the second step reaction, thereby realizing the secondary utilization of solid waste and being beneficial to environmental protection.

[0018] The method of the present invention has the advantages of simple and readily available raw materials, mild reaction conditions, a first-step reaction temperature of 50-70° C., a second-step reaction temperature of 20-40° C., a high reaction yield of 85.6-92.1%, and no need to separate the catalyst and the solvent, which can be reused, thereby reducing production costs. DETAILED DESCRIPTION

[0019] To help those skilled in the art better understand the technical solutions of the present invention, the following clearly and completely describes the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention. Example 1

[0020] (1) Add 4 mmol of cuprous chloride, 0.2 mol of zinc powder, and 2 mol of nitrobenzene to a 1 L glass reactor, raise the temperature to 70°C, and then dropwise add 0.2 mol of benzyl chloride over a period of 1 hour. After the addition is complete, keep the temperature for 4 hours to obtain reaction material A.

[0021] (2) The obtained reaction material A was cooled to 0°C, and then 1.2 mol of bromine chloride was added dropwise for 1 hour. After the addition was completed, the temperature was raised to 20°C and kept warm for 6 hours to obtain reaction material B;

[0022] (3) The reaction material B prepared in step (2) was neutralized by adding a 10% by mass sodium sulfite aqueous solution until the color of the reaction solution changed from reddish brown to colorless, and then neutralized by adding a 10% by mass sodium bicarbonate aqueous solution until the pH value of the reaction solution was 7-8. The reaction solution was then filtered, and the solid was washed three times with 100 mL by mass 36% hydrochloric acid, then washed three times with 100 mL by mass hot water, and finally washed three times with 100 mL by mass acetonitrile. After drying in a vacuum drying oven at 120°C for 24 hours, 85.6 g of finished decabromodiphenylethane was obtained, with a yield of 88.2%. After testing, the decabromodiphenylethane had a whiteness of 90.6°, a bromine content of 81.2%, a 1% TGA (thermogravimetric analysis) of 346.8°C, and a 5% TGA of 374.4°C. Example 2

[0023] (1) Add 0.02 mol of cuprous chloride, 0.12 mol of iron powder, and 4 mol of nitrobenzene to a 1 L glass reactor, raise the temperature to 50°C, and then dropwise add 0.2 mol of benzyl chloride over a period of 0.5 hours. After the addition is complete, keep the temperature for 7 hours to obtain reaction material A.

[0024] (2) The obtained reaction mass was cooled to 10°C, and then 1.6 mol of bromine chloride was added dropwise for 2 hours. After the addition was completed, the temperature was raised to 40°C and kept warm for 3 hours to obtain reaction mass B;

[0025] (3) The reaction material B prepared in step (2) was neutralized by adding a 10% by mass sodium sulfite aqueous solution until the color of the reaction solution changed from reddish brown to colorless, and then neutralized by adding a 10% by mass sodium bicarbonate aqueous solution until the pH value of the reaction solution was 7-8. The reaction solution was then filtered, and the solid was washed three times with 100 mL by mass 36% hydrochloric acid, then three times with 100 mL by mass hot water, and finally three times with 100 mL by mass acetonitrile. After drying in a vacuum drying oven at 160°C for 8 hours, 83.1 g of finished decabromodiphenylethane was obtained, with a yield of 85.6%. After testing, the whiteness of decabromodiphenylethane was 91.2°, the bromine content was 82.4%, the 1% TGA was 345.6°C, and the 5% TGA was 373.8°C. Example 3

[0026] (1) Add 0.01 mol of cuprous chloride, 0.16 mol of zinc powder, and 3 mol of nitrobenzene to a 1 L glass reactor, raise the temperature to 60°C, and then dropwise add 0.2 mol of benzyl chloride over a period of 0.8 hours. After the addition is complete, keep the temperature for 6 hours to obtain reaction material A.

[0027] (2) The obtained reaction mass was cooled to 5°C, and then 1.4 mol of bromine chloride was added dropwise over a period of 1.5 hours. After the addition was complete, the temperature was raised to 30°C and kept warm for 4 hours to obtain reaction mass B.

[0028] (3) The reaction material B prepared in step (2) was neutralized by adding a 10% by mass sodium sulfite aqueous solution until the color of the reaction solution changed from reddish brown to colorless, and then neutralized by adding a 10% by mass sodium bicarbonate aqueous solution until the pH value of the reaction solution was 7-8. The reaction solution was then filtered, and the solid was washed three times with 100 mL by mass 36% hydrochloric acid, then three times with 100 mL by mass hot water, and finally three times with 100 mL by mass acetonitrile. After drying in a vacuum drying oven at 150°C for 12 hours, 87.7 g of finished decabromodiphenylethane was obtained, with a yield of 90.3%. After testing, the whiteness of decabromodiphenylethane was 91.8°, the bromine content was 81.9%, the 1% TGA was 343.2°C, and the 5% TGA was 374.2°C. Example 4

[0029] (1) Add 0.01 mol of cuprous chloride, 0.2 mol of iron powder, and 4 mol of nitrobenzene to a 1 L glass reactor, raise the temperature to 60°C, and then dropwise add 0.2 mol of benzyl chloride over a period of 1 hour. After the addition is complete, keep the temperature for 5 hours to obtain reaction material A.

[0030] (2) The obtained reaction mass was cooled to 5°C, and then 1.2 mol of bromine chloride was added dropwise over a period of 2 hours. After the addition was complete, the temperature was raised to 30°C and the temperature was kept constant for 5 hours to obtain reaction mass B;

[0031] (3) The reaction material B prepared in step (2) was neutralized by adding a 10% by mass sodium sulfite aqueous solution until the color of the reaction solution changed from reddish brown to colorless, and then neutralized by adding a 10% by mass sodium bicarbonate aqueous solution until the pH value of the reaction solution was 7-8. The reaction solution was then filtered, and the solid was washed three times with 100 mL by mass 36% hydrochloric acid, then three times with 100 mL by mass hot water, and finally three times with 100 mL by mass acetonitrile. After drying in a vacuum drying oven at 140°C for 20 hours, 85.2 g of finished decabromodiphenylethane was obtained, with a yield of 87.8%. After testing, the whiteness of decabromodiphenylethane was 90.2°, the bromine content was 81.4%, the 1% TGA was 344.7°C, and the 5% TGA was 374.5°C. Example 5

[0032] (1) Add 0.02 mol of cuprous chloride, 0.12 mol of zinc powder, and 2 mol of nitrobenzene to a 1 L glass reactor, raise the temperature to 70°C, and then dropwise add 0.2 mol of benzyl chloride over a period of 1 hour. After the addition is complete, keep the temperature for 4 hours to obtain reaction material A.

[0033] (2) The obtained reaction mass was cooled to 0°C, and then 1.2 mol of bromine chloride was added dropwise for 1 hour. After the addition was completed, the temperature was raised to 20°C and kept warm for 6 hours to obtain reaction mass B;

[0034] (3) The reaction material B prepared in step (2) was neutralized by adding a 10% by mass sodium sulfite aqueous solution until the color of the reaction solution changed from reddish brown to colorless, and then neutralized by adding a 10% by mass sodium bicarbonate aqueous solution until the pH value of the reaction solution was 7-8. The reaction solution was then filtered, and the solid was washed three times with 100 mL by mass 36% hydrochloric acid, then three times with 100 mL by mass hot water, and finally three times with 100 mL by mass acetonitrile. After drying in a vacuum drying oven at 150°C for 15 hours, 89.4 g of finished decabromodiphenylethane was obtained, with a yield of 92.1%. After testing, the decabromodiphenylethane had a whiteness of 92.6°, a bromine content of 81.6%, a 1% TGA of 346.5°C, and a 5% TGA of 376.5°C. Example 6

[0035] (1) Add 0.016 mol of cuprous chloride, 0.16 mol of iron powder, and 3 mol of nitrobenzene to a 1 L glass reactor, raise the temperature to 70°C, and then dropwise add 0.2 mol of benzyl chloride over a period of 0.5 hours. After the addition is complete, keep the temperature for 5 hours to obtain reaction material A.

[0036] (2) The obtained reaction mass was cooled to 10°C, and then 1.4 mol of bromine chloride was added dropwise for 1 hour. After the addition was completed, the temperature was raised to 40°C and kept warm for 4 hours to obtain reaction mass B;

[0037] (3) The reaction material B prepared in step (2) was neutralized by adding a 10% by mass sodium sulfite aqueous solution until the color of the reaction solution changed from reddish brown to colorless, and then neutralized by adding a 10% by mass sodium bicarbonate aqueous solution until the pH value of the reaction solution was 7-8. The reaction solution was then filtered, and the solid was washed three times with 100 mL by mass 36% hydrochloric acid, then three times with 100 mL by mass hot water, and finally three times with 100 mL by mass acetonitrile. After drying in a vacuum drying oven at 160°C for 10 hours, 70.2 g of finished decabromodiphenylethane was obtained, with a yield of 91.5%. After testing, the whiteness of decabromodiphenylethane was 91.4°, the bromine content was 82.1%, the 1% TGA was 345.2°C, and the 5% TGA was 375.3°C. Comparative Example 1

[0038] The difference from Example 1 is that the reaction temperature in step (1) was changed from 70°C to 80°C, while other conditions remained the same. After drying, the product yielded 77.9 g of decabromodiphenylethane, with a yield of 80.3%. Testing revealed that the decabromodiphenylethane had a whiteness of 88.6°, a bromine content of 81.3%, a 1% TGA (thermogravimetric analysis) of 343.8°C, and a 5% TGA of 373.6°C. Comparative Example 2

[0039] The difference from Example 1 is that the reaction temperature in step (1) was changed from 70°C to 40°C, while other conditions remained the same. After drying, the product yielded 76.3 g of decabromodiphenylethane, with a yield of 78.6%. Testing revealed that the decabromodiphenylethane had a whiteness of 87.5°, a bromine content of 81.5%, a 1% TGA (thermogravimetric analysis) of 343.2°C, and a 5% TGA of 373.5°C.

[0040]

[0041] It can be seen from Table 1 that the technical solution provided by the present application has a decabromodiphenylethane yield of 85.6-92.1%, while the yield of decabromodiphenylethane is lower when the comparative example and the embodiment differ only in reaction temperature, indicating that the reaction temperature effect of the present invention is better.

[0042] In addition to the above embodiments, the present invention also includes other implementation methods. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the scope of protection of the claims of the present invention.

Claims

1. A method for synthesizing decabromodiphenylethane, characterized in that: The following steps are involved: (1) Mix cuprous chloride, reducing metal powder and nitrobenzene and heat to 50-70°C, add benzyl chloride dropwise for 0.5-1 hour, and keep warm for 4-7 hours to obtain reaction material A; (2) Cooling the reaction material A obtained in step (1) to 0-10°C, adding bromine chloride dropwise thereto for 1-2 hours, heating the reaction to 20-40°C, and keeping the temperature for 3-6 hours to obtain reaction material B; (3) adding a sodium sulfite aqueous solution to the reaction material B prepared in step (2) for neutralization until the color of the reaction solution changes from reddish brown to colorless, and then adding a sodium bicarbonate aqueous solution for neutralization until the pH value of the reaction solution reaches 7 to 8, and then filtering the reaction solution, washing, and drying to obtain decabromodiphenylethane; In step (3), the washing is first with concentrated hydrochloric acid, then with hot water, and finally with acetonitrile; the drying temperature is 120-160° C., and the time is 8-24 h.

2. The method for synthesizing decabromodiphenylethane according to claim 1, wherein In the step (1), the reducing metal powder is zinc powder or iron powder, and the molar ratio of the reducing metal powder to benzyl chloride is 0.6 to 1:

1.

3. The method for synthesizing decabromodiphenylethane according to claim 1, wherein In the step (1), the molar ratio of cuprous chloride to benzyl chloride is 2 to 10:

100.

4. The method for synthesizing decabromodiphenylethane according to claim 1, wherein In the step (1), the molar ratio of nitrobenzene to benzyl chloride is 10-20:

1.

5. The method for synthesizing decabromodiphenylethane according to claim 1, wherein In the step (2), the molar ratio of bromine chloride to benzyl chloride is 6 to 8:1.

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