Method for synthesizing decabromodiphenylethane

Abstract

The invention provides a method for synthesizing decabromodiphenylethane, and belongs to the technical field of brominated flame retardant synthesis. The decabromodiphenylethane is synthesized by taking benzyl chloride as a reaction raw material and bromine chloride as a brominating agent through a one-pot two-step method. The metal chloride generated in the first step is used as a catalyst in the second step, and the diphenylethane generated in the first step can be directly subjected to bromination reaction without being separated. The method for synthesizing the decabromodiphenyl ethane 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 in particular relates to a method for synthesizing decabromodiphenylethane. Background Art

[0002] Decabromodiphenyl ethane is a widely used new brominated flame retardant with good thermal stability, excellent fire resistance and UV resistance, and no ether bonds in its molecular structure. It 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] In the prior art, the preparation methods of decabromodiphenylethane all use 1,2-diphenylethane as raw material, and use solvent method or excess bromine method to prepare decabromodiphenylethane. At present, the general industry mostly adopts the excess bromine method, heating 1,2-diphenylethane to a molten state, adding excess bromine to prepare decabromodiphenylethane products, but this method also has problems such as pipeline blockage, yellow product color, and high free bromine content. Regardless of which method is used, 1,2-diphenylethane is required as raw material, and the synthesis and separation and purification process of 1,2-diphenylethane is relatively complicated, resulting in a high production cost of decabromodiphenylethane using 1,2-diphenylethane as raw material.

[0004] The Chinese patent document with publication number CN101643387A discloses a method for preparing low-free-bromine decabromodiphenylethane, which reduces the free-bromine content of the product through secondary distillation and ball milling, and the prepared decabromodiphenylethane product has a high whiteness. However, the patent process is complicated, the secondary distillation consumes a lot of energy, and it is difficult to achieve large-scale industrial production.

[0005] The Chinese patent document with publication number CN114213210 A discloses a method for preparing decabromodiphenylethane, which improves the whiteness and yield of decabromodiphenylethane by preparing a supported catalyst. However, the catalyst preparation in this patent is complicated, and the recycling of the catalyst is not reflected, resulting in high production costs of decabromodiphenylethane, which is not conducive to industrial production. Summary of the invention

[0006] The purpose of the present invention is to provide a method for synthesizing decabromodiphenylethane. The method uses benzyl chloride as a raw material and bromine chloride as a brominating agent, and realizes the synthesis of decabromodiphenylethane through a one-pot two-step method. 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: (1) Mix cuprous chloride, reducing metal powder and nitrobenzene and heat them to 50-70°C, add benzyl chloride dropwise for 0.5-1h, and keep the temperature for 4-7h 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 is 7 to 8, and then filtering the reaction solution, washing, and drying to obtain decabromodiphenylethane.

[0008] The chemical reaction process in the above steps is as follows:

[0009] 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.

[0010] Preferably, in step (2), the molar ratio of bromine chloride to benzyl chloride is 6 to 8:1.

[0011] Preferably, in step (3), the washing is firstly washing with concentrated hydrochloric acid, then washing with hot water, and finally washing with acetonitrile; the drying temperature is 120-160° C., and the drying time is 8-24 h.

[0012] The beneficial effects of the present invention are: The method of the invention realizes the preparation of decabromodiphenylethane through a one-pot two-step method, 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.

[0013] The method of the 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%, no need to separate the catalyst and the solvent, and they can be reused, thereby reducing the production cost. DETAILED DESCRIPTION

[0014] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention. Example 1

[0015] (1) Add 4 mmol of cuprous chloride, 0.2 mol of zinc powder and 2 mol of nitrobenzene into a 1 L glass reactor, raise the temperature to 70°C, and then dropwise add 0.2 mol of benzyl chloride for 1 hour. After the dropwise addition is complete, keep the temperature for 4 hours to obtain reaction material A; (2) Cool the obtained reaction material A to 0°C, then add 1.2 mol of bromine chloride dropwise for 1 hour. After the addition is complete, raise the temperature to 20°C and keep warm for 6 hours to obtain reaction material B; (3) The reaction material B prepared in step (2) was added with a 10% sodium sulfite aqueous solution for neutralization until the color of the reaction solution changed from reddish brown to colorless, and then a 10% sodium bicarbonate aqueous solution was added for neutralization until the pH value of the reaction solution was 7-8, and then the reaction solution was filtered, and the solid was washed 3 times with 100 mL of 36% hydrochloric acid, 3 times with 100 mL of hot water, and finally 3 times with 100 mL of acetonitrile. After drying in a vacuum drying oven at 120°C for 24 hours, 85.6 g of decabromodiphenylethane was obtained, with a yield of 88.2%. After testing, the whiteness of decabromodiphenylethane was 90.6°, the bromine content was 81.2%, the 1% TGA (thermogravimetric analysis) was 346.8°C, and the 5% TGA was 374.4°C. Example 2

[0016] (1) Add 0.02 mol of cuprous chloride, 0.12 mol of iron powder and 4 mol of nitrobenzene into a 1 L glass reactor, raise the temperature to 50°C, and then dropwise add 0.2 mol of benzyl chloride for 0.5 hours. After the dropwise addition is complete, keep the temperature for 7 hours to obtain reaction material A; (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; (3) The reaction material B prepared in step (2) was added with a 10% sodium sulfite aqueous solution for neutralization until the color of the reaction solution changed from reddish brown to colorless, and then a 10% sodium bicarbonate aqueous solution was added for neutralization until the pH value of the reaction solution was 7-8, and then the reaction solution was filtered, and the solid was washed 3 times with 100 mL of 36% hydrochloric acid, 3 times with 100 mL of hot water, and finally 3 times with 100 mL of acetonitrile. After drying in a vacuum drying oven at 160°C for 8 hours, 83.1 g of 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

[0017] (1) Add 0.01 mol of cuprous chloride, 0.16 mol of zinc powder and 3 mol of nitrobenzene into a 1 L glass reactor, raise the temperature to 60°C, then dropwise add 0.2 mol of benzyl chloride for 0.8 hours. After the addition is complete, keep the temperature for 6 hours to obtain reaction material A; (2) The obtained reaction mass was cooled to 5°C, and then 1.4 mol of bromine chloride was added dropwise for 1.5 hours. After the addition was completed, the temperature was raised to 30°C and kept warm for 4 hours to obtain reaction mass B; (3) The reaction material B prepared in step (2) was added with a 10% sodium sulfite aqueous solution for neutralization until the color of the reaction solution changed from reddish brown to colorless, and then a 10% sodium bicarbonate aqueous solution was added for neutralization until the pH value of the reaction solution was 7-8, and then the reaction solution was filtered, and the solid was washed 3 times with 100 mL of 36% hydrochloric acid, 3 times with 100 mL of hot water, and finally 3 times with 100 mL of acetonitrile. After drying in a vacuum drying oven at 150°C for 12 hours, 87.7 g of 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

[0018] (1) Add 0.01 mol of cuprous chloride, 0.2 mol of iron powder and 4 mol of nitrobenzene into a 1 L glass reactor, raise the temperature to 60°C, and then dropwise add 0.2 mol of benzyl chloride for 1 hour. After the dropwise addition is complete, keep the temperature for 5 hours to obtain reaction material A; (2) The obtained reaction mass was cooled to 5°C, and then 1.2 mol of bromine chloride was added dropwise for 2 hours. After the addition was completed, the temperature was raised to 30°C and kept warm for 5 hours to obtain reaction mass B; (3) The reaction material B prepared in step (2) was added with a 10% sodium sulfite aqueous solution for neutralization until the color of the reaction solution changed from reddish brown to colorless, and then a 10% sodium bicarbonate aqueous solution was added for neutralization until the pH value of the reaction solution was 7-8, and then the reaction solution was filtered, and the solid was washed 3 times with 100 mL of 36% hydrochloric acid, 3 times with 100 mL of hot water, and finally 3 times with 100 mL of acetonitrile. After drying in a vacuum drying oven at 140°C for 20 hours, 85.2 g of 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

[0019] (1) Add 0.02 mol of cuprous chloride, 0.12 mol of zinc powder and 2 mol of nitrobenzene into a 1 L glass reactor, raise the temperature to 70°C, and then dropwise add 0.2 mol of benzyl chloride for 1 hour. After the dropwise addition is complete, keep the temperature for 4 hours to obtain reaction material A; (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; (3) The reaction material B prepared in step (2) was added with a 10% sodium sulfite aqueous solution for neutralization until the color of the reaction solution changed from reddish brown to colorless, and then a 10% sodium bicarbonate aqueous solution was added for neutralization until the pH value of the reaction solution was 7-8, and then the reaction solution was filtered, and the solid was washed 3 times with 100 mL of 36% hydrochloric acid, 3 times with 100 mL of hot water, and finally 3 times with 100 mL of acetonitrile. After drying in a vacuum drying oven at 150°C for 15 hours, 89.4 g of decabromodiphenylethane was obtained, with a yield of 92.1%. After testing, the whiteness of decabromodiphenylethane was 92.6°, the bromine content was 81.6%, the 1% TGA was 346.5°C, and the 5% TGA was 376.5°C. Example 6

[0020] (1) Add 0.016 mol of cuprous chloride, 0.16 mol of iron powder and 3 mol of nitrobenzene into a 1 L glass reactor, raise the temperature to 70°C, and then dropwise add 0.2 mol of benzyl chloride for 0.5 hours. After the dropwise addition is complete, keep the temperature for 5 hours to obtain reaction material A; (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; (3) The reaction material B prepared in step (2) was added with a 10% sodium sulfite aqueous solution for neutralization until the color of the reaction solution changed from reddish brown to colorless, and then a 10% sodium bicarbonate aqueous solution was added for neutralization until the pH value of the reaction solution was 7-8, and then the reaction solution was filtered, and the solid was washed 3 times with 100 mL of 36% hydrochloric acid, 3 times with 100 mL of hot water, and finally 3 times with 100 mL of acetonitrile. After drying in a vacuum drying oven at 160°C for 10 hours, 70.2 g of 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

[0021] The difference from Example 1 is that the reaction temperature in step (1) is changed from 70°C to 80°C, and the other conditions are the same. After drying, the product is 77.9g of decabromodiphenylethane finished product, with a yield of 80.3%. After testing, the whiteness of decabromodiphenylethane is 88.6°, the bromine content is 81.3%, the 1% TGA (thermogravimetric analysis) is 343.8°C, and the 5% TGA is 373.6°C. Comparative Example 2

[0022] The difference from Example 1 is that the reaction temperature in step (1) is changed from 70°C to 40°C, and the other conditions are the same. After drying, the product is 76.3g of decabromodiphenylethane finished product, with a yield of 78.6%. After testing, the whiteness of decabromodiphenylethane is 87.5°, the bromine content is 81.5%, the 1% TGA (thermogravimetric analysis) is 343.2°C, and the 5% TGA is 373.5°C.

[0023]

[0024] From Table 1, it can be seen that the technical solution provided by the present application can obtain a decabromodiphenylethane yield of 85.6-92.1%, while the yield of decabromodiphenylethane will be reduced if the comparative example and the embodiment differ only in reaction temperature, indicating that the reaction temperature effect of the present invention is better.

[0025] In addition to the above embodiments, the present invention also includes other implementation modes. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the protection scope 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 them to 50-70°C, add benzyl chloride dropwise for 0.5-1h, and keep the temperature for 4-7h 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 is 7 to 8, and then filtering the reaction solution, washing, and drying to obtain decabromodiphenylethane.

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

1.

6. The method for synthesizing decabromodiphenylethane according to claim 1, characterized in that: In the step (3), the washing is firstly 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 hours.

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