A method for synthesizing decabromodiphenylethane

Abstract

The present invention provides a method for synthesizing decabromodiphenylethane, which belongs to the technical field of brominated flame retardant synthesis. The present invention uses benzene and 1,2-dichloroethane as reaction raw materials, bromine chloride as a brominating agent, and nitrobenzene as a solvent to synthesize decabromodiphenylethane through a one-pot, two-step process. The diphenylethane produced in the first step does not need to be separated and can be directly used to carry out a bromination reaction using the catalyst in the first step, avoiding the secondary addition of the catalyst. The decabromodiphenylethane synthesis method of the present invention has the advantages of simple and readily available raw materials, mild reaction conditions, low cost, 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] Decabromodiphenylethane is a broad-spectrum additive flame retardant. It appears as a white powder with a theoretical bromine content of 82.3%. It has the advantages of good thermal stability, fire resistance, and excellent UV resistance. In addition, there are no ether bonds in its molecular structure, and it will not produce carcinogenic substances such as PBDD and PBDF under high temperature conditions. It is particularly suitable for flame retardant production of high-end materials for computers, fax machines, telephones, copiers, and home appliances.

[0003] The existing methods for preparing decabromodiphenylethane all use 1,2-diphenylethane as the raw material and prepare decabromodiphenylethane through a solvent method or an 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 prepare the decabromodiphenylethane product. However, this method also has the problem of pipeline blockage, and bromine, catalyst and target product are easily wrapped and agglomerated, resulting in a yellow product color and a 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 of decabromodiphenylethane using 1,2-diphenylethane as the raw material.

[0004] Chinese invention patent publication number CN114213210A discloses a method for preparing decabromodiphenylethane. By grinding and stirring 1,2-diphenylethane powder with an excess of a brominating agent while conducting a bromination reaction, this method overcomes the technical issues of existing technologies, such as the need to heat the raw material 1,2-diphenylethane, the tendency of dropwise addition of molten 1,2-diphenylethane to hinder the smooth completion of the bromination reaction, and the risk of clogging the addition tube. However, this patent's complex operation and high requirements for the raw material 1,2-diphenylethane make it difficult to implement large-scale industrial production.

[0005] Chinese invention patent publication number 114213210 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 provides a method for synthesizing decabromodiphenylethane using benzene and 1,2-dichloroethane as reaction raw materials, bromine chloride as a brominating agent, and nitrobenzene as a solvent, via a one-pot, two-step process. The method has the advantages of simple and readily available raw materials, mild reaction conditions, high product yield, and low production cost.

[0007] The technical solution of the present invention is: a method for synthesizing decabromodiphenylethane, the specific steps of which are as follows:

[0008] (1) Mix the catalyst, benzene and nitrobenzene, raise the temperature to 40-70°C, add 1,2-dichloroethane dropwise for 1-3 hours, and keep the temperature for 4-7 hours to obtain reaction material A;

[0009] (2) The obtained reaction material A is subjected to reduced pressure distillation to remove excess benzene, and then cooled to 0-10°C, and bromine chloride is added dropwise for 1-2 hours. After the addition is complete, the temperature is raised to 20-40°C and kept warm for 3-6 hours to obtain reaction material B;

[0010] (3) The reaction material B prepared in step (2) is added to a sodium sulfite aqueous solution 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 is 7 to 8. The reaction solution is then filtered, washed, and dried to obtain the finished decabromodiphenylethane.

[0011] The chemical reaction process of the above synthesis method is as follows:

[0012] Preferably, the catalyst in step (1) is one of aluminum trichloride, ferric trichloride, and antimony trichloride, and the molar ratio of the catalyst, benzene, and 1,2-dichloroethane is 0.02-0.1:2-5:1; the molar ratio of nitrobenzene to 1,2-dichloroethane is 5-15:1.

[0013] Preferably, the molar ratio of bromine chloride to 1,2-dichloroethane in step (2) is 12 to 15:1.

[0014] Preferably, the molar ratio of bromine chloride to 1,2-dichloroethane in step (3) is 12 to 15:1.

[0015] The beneficial effects of the present invention are:

[0016] The technical solution provided by 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 catalyst of the first step to carry out the bromination reaction of the second step, thereby realizing the secondary utilization of the catalyst and reducing the amount of the catalyst used.

[0017] The technical solution provided by the present invention uses benzene and 1,2-dichloroethane as reaction raw materials, bromine chloride as a brominating agent, and nitrobenzene as a solvent. The raw materials are simple and easily available, the reaction conditions are mild, the reaction temperature of the first step is 40-70°C, and the reaction temperature of the second step is 20-40°C. The catalyst and the solvent do not need to be separated and can be reused, thereby reducing production costs, achieving a high product yield of 86.4-90.5%, and being easy to industrialize. DETAILED DESCRIPTION

[0018] 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

[0019] (1) Add 4 mmol of aluminum chloride, 0.4 mol of benzene and 1 mol of nitrobenzene to a 1 L glass reactor, raise the temperature to 70 ° C, and then dropwise add 0.2 mol of 1,2-dichloroethane for 1 hour. After the addition is complete, keep the temperature for 4 hours to obtain reaction material A;

[0020] (2) The obtained reaction material A was cooled to 30°C, and the excess benzene was removed by reduced pressure distillation at a vacuum degree of -0.08 to -0.09 MPa. Then, the reaction material A was cooled to 0°C, and 2.4 mol of bromine chloride was added dropwise over a period of 2 hours. After the addition was complete, the temperature was raised to 20°C and the temperature was kept constant for 6 hours to obtain the reaction material B.

[0021] (3) The reaction material B prepared in step (2) was neutralized by adding a 10% aqueous sodium sulfite solution until the color of the reaction solution changed from reddish brown to colorless, and then neutralized by adding a 10% aqueous sodium bicarbonate solution until the pH value of the reaction solution was 7-8. The reaction solution was then filtered to obtain a crude decabromodiphenylethane product. The crude product was washed with acetonitrile three times, then washed with 80°C hot water twice, and dried in a vacuum drying oven at 150°C for 10 hours to obtain 167.8g of finished decabromodiphenylethane, with a yield of 86.4%. After testing, the decabromodiphenylethane had a whiteness of 91.2°, a bromine content of 81.5%, a 1% TGA (thermogravimetric analysis) of 349.2°C, and a 5% TGA of 381.4°C. Example 2

[0022] (1) Add 0.02 mol of ferric chloride, 1 mol of benzene and 3 mol of nitrobenzene to a 1 L glass reactor, raise the temperature to 40 ° C, and then dropwise add 0.2 mol of 1,2-dichloroethane over 3 hours. After the addition is complete, keep the temperature for 7 hours to obtain reaction material A;

[0023] (2) The obtained reaction material A was cooled to 30°C, and the excess benzene was removed by reduced pressure distillation at a vacuum degree of -0.08 to -0.09 MPa. Then, the reaction material A was cooled to 10°C, and 3 mol of bromine chloride was added dropwise over a period of 1 hour. After the addition was complete, the temperature was raised to 40°C and kept warm for 3 hours to obtain the reaction material B.

[0024] (3) The reaction material B prepared in step (2) was neutralized by adding a 10% aqueous sodium sulfite solution until the color of the reaction solution changed from reddish brown to colorless, and then neutralized by adding a 10% aqueous sodium bicarbonate solution until the pH value of the reaction solution was 7-8. The reaction solution was then filtered to obtain a crude decabromodiphenylethane product. The crude product was washed with acetonitrile three times, then washed with 80°C hot water twice, and dried in a vacuum drying oven at 150°C for 10 hours to obtain 175.8g of finished decabromodiphenylethane, with a yield of 90.5%. After testing, the decabromodiphenylethane had a whiteness of 91.5°, a bromine content of 82.1%, a 1% TGA of 344.4°C, and a 5% TGA of 375.6°C. Example 3

[0025] (1) Add 0.01 mol of antimony trichloride, 0.6 mol of benzene and 1.6 mol of nitrobenzene to a 1 L glass reactor, raise the temperature to 60 ° C, and then dropwise add 0.2 mol of 1,2-dichloroethane over a period of 2 hours. After the addition is complete, keep the temperature for 5 hours to obtain reaction material A;

[0026] (2) The obtained reaction material A was cooled to 30°C, and the excess benzene was removed by reduced pressure distillation at a vacuum degree of -0.08 to -0.09 MPa. Then, the reaction material A was cooled to 5°C, and 2.6 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 the reaction material B.

[0027] (3) The reaction material B prepared in step (2) was neutralized by adding a 10% aqueous sodium sulfite solution until the color of the reaction solution changed from reddish brown to colorless, and then neutralized by adding a 10% aqueous sodium bicarbonate solution until the pH value of the reaction solution was 7-8. The reaction solution was then filtered to obtain a crude decabromodiphenylethane product. The crude product was washed with acetonitrile three times, then washed with 80°C hot water twice, and dried in a vacuum drying oven at 150°C for 10 hours to obtain 171.7 g of finished decabromodiphenylethane, with a yield of 88.4%. After testing, the decabromodiphenylethane had a whiteness of 92.6°, a bromine content of 81.8%, a 1% TGA of 345.8°C, and a 5% TGA of 378.6°C. Example 4

[0028] (1) Add 0.012 mol of aluminum chloride, 0.8 mol of benzene, and 2.4 mol of nitrobenzene to a 1 L glass reactor, raise the temperature to 50°C, and then dropwise add 0.2 mol of 1,2-dichloroethane over a period of 2 hours. After the addition is complete, keep the temperature for 6 hours to obtain reaction material A.

[0029] (2) The obtained reaction material A was cooled to 30°C, and the excess benzene was removed by reduced pressure distillation at a vacuum degree of -0.08 to -0.09 MPa. Then, the reaction material A was cooled to 8°C, and 2.8 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 the reaction material B.

[0030] (3) The reaction material B prepared in step (2) was neutralized by adding a 10% aqueous sodium sulfite solution until the color of the reaction solution changed from reddish brown to colorless, and then neutralized by adding a 10% aqueous sodium bicarbonate solution until the pH value of the reaction solution was 7-8. The reaction solution was then filtered to obtain crude decabromodiphenylethane. The crude product was washed three times with acetonitrile and then twice with 80°C hot water. After drying in a vacuum drying oven at 150°C for 10 hours, 173.3 g of finished decabromodiphenylethane was obtained, with a yield of 89.2%. After testing, the decabromodiphenylethane had a whiteness of 92.1°, a bromine content of 81.3%, a 1% TGA of 346.7°C, and a 5% TGA of 377.8°C. Example 5

[0031] (1) Add 8 mmol of aluminum chloride, 0.6 mol of benzene, and 1.2 mol of nitrobenzene to a 1 L glass reactor, raise the temperature to 50°C, and then dropwise add 0.2 mol of 1,2-dichloroethane over a period of 3 hours. After the addition is complete, keep the temperature for 5 hours to obtain a reaction mass;

[0032] (2) The obtained reaction mass was cooled to 30°C, and the excess benzene was removed by reduced pressure distillation at a vacuum degree of -0.08 to -0.09 MPa. Then, the reaction mass was cooled to 3°C, and 2.6 mol of bromine chloride was added dropwise over a period of 1 hour. After the addition was complete, the temperature was raised to 25°C and the temperature was kept constant for 6 hours to obtain the reaction mass.

[0033] (3) The reaction material B prepared in step (2) was neutralized by adding a 10% aqueous sodium sulfite solution until the color of the reaction solution changed from reddish brown to colorless, and then neutralized by adding a 10% aqueous sodium bicarbonate solution until the pH value of the reaction solution was 7-8. The reaction solution was then filtered to obtain crude decabromodiphenylethane. The crude product was washed three times with acetonitrile and then twice with 80°C hot water. After drying in a vacuum drying oven at 150°C for 10 hours, 172.3 g of finished decabromodiphenylethane was obtained, with a yield of 88.7%. After testing, the decabromodiphenylethane had a whiteness of 90.7°, a bromine content of 80.8%, a 1% TGA of 347.6°C, and a 5% TGA of 378.8°C. Example 6

[0034] (1) Add 0.016 mol of antimony trichloride, 0.8 mol of benzene and 2 mol of nitrobenzene to a 1 L glass reactor, raise the temperature to 60 ° C, and then dropwise add 0.2 mol of 1,2-dichloroethane. The addition time is 1 hour. After the addition is complete, keep the temperature for 6 hours to obtain a reaction mass;

[0035] (2) The obtained reaction mass was cooled to 30°C, and the excess benzene was removed by reduced pressure distillation at a vacuum degree of -0.08 to -0.09 MPa. The reaction mass was then cooled to 6°C, and 2.4 mol of bromine chloride was added dropwise over a period of 1.5 hours. After the addition was complete, the temperature was raised to 35°C and the temperature was maintained for 5 hours to obtain the reaction mass.

[0036] (3) The reaction material B prepared in step (2) was neutralized by adding a 10% aqueous sodium sulfite solution until the color of the reaction solution changed from reddish brown to colorless, and then neutralized by adding a 10% aqueous sodium bicarbonate solution until the pH value of the reaction solution was 7-8. The reaction solution was then filtered to obtain a crude decabromodiphenylethane product. The crude product was washed with acetonitrile three times, then washed with 80°C hot water twice, and dried in a vacuum drying oven at 150°C for 10 hours to obtain 171.1 g of finished decabromodiphenylethane, with a yield of 88.1%. After testing, the decabromodiphenylethane had a whiteness of 90.4°, a bromine content of 81.1%, a 1% TGA of 346.2°C, and a 5% TGA of 378.8°C. Comparative Example 1

[0037] 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 160.2 g of decabromodiphenylethane, with a yield of 82.5%. Testing revealed that the decabromodiphenylethane had a whiteness of 87.8°, a bromine content of 81.4%, a 1% TGA (thermogravimetric analysis) of 344.2°C, and a 5% TGA of 374.6°C. Comparative Example 2

[0038] The difference from Example 1 is that the reaction temperature in step (1) was changed from 70°C to 30°C, while other conditions remained the same. After drying, the product yielded 154.6 g of decabromodiphenylethane, with a yield of 79.6%. Testing revealed that the decabromodiphenylethane had a whiteness of 87.5°, a bromine content of 81.2%, a 1% TGA (thermogravimetric analysis) of 343.2°C, and a 5% TGA of 373.5°C.

[0039]

[0040] It can be seen from Table 1 that the technical solution provided by the present application has a decabromodiphenylethane yield of 86.4-90.5%, while the comparative example and the embodiment have a lower decabromodiphenylethane yield when the reaction temperature is different, indicating that the reaction temperature effect of the present invention is better.

[0041] 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 the catalyst, benzene and nitrobenzene, raise the temperature to 40-70°C, add 1,2-dichloroethane dropwise for 1-3 hours, and keep the temperature for 4-7 hours to prepare reaction material A; the molar ratio of nitrobenzene to 1,2-dichloroethane is 5-15:1; (2) The obtained reaction material A is subjected to reduced pressure distillation to remove excess benzene, and then cooled to 0-10°C, and bromine chloride is added dropwise for 1-2 hours. After the addition is complete, the temperature is raised to 20-40°C and kept warm for 3-6 hours to obtain reaction material B; (3) adding a sodium sulfite aqueous solution to neutralize the reaction material B prepared in step (2) until the color of the reaction solution changes from reddish brown to colorless, and then adding a sodium bicarbonate aqueous solution to neutralize until the pH value of the reaction solution reaches 7 to 8, and then filtering, washing, and drying the reaction solution to obtain the finished decabromodiphenylethane; The catalyst described in step (1) is one of aluminum trichloride, ferric trichloride, and antimony trichloride, and the molar ratio of the catalyst, benzene, and dichloroethane is 0.02-0.1: 2-5:

1.

2. The method for synthesizing decabromodiphenylethane according to claim 1, wherein: The molar ratio of bromine chloride to 1,2-dichloroethane in step (2) is 12 to 15:1.

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