Synthesis method of bromotriazine

Abstract

The invention discloses a synthesis method of bromo-triazine, which belongs to the technical field of organic synthesis, and comprises the following steps: preparing an alumina-loaded N, N-dimethylaminopyridine catalyst, filling the alumina-loaded N, N-dimethylaminopyridine catalyst in a fixed bed reactor, introducing tribromophenol and metal oxide mixed slurry and cyanuric chloride slurry, carrying out a reaction for 2-4 hours, and carrying out a reaction for 2-4 hours to obtain the bromo-triazine. Raising the temperature for reaction to obtain a crude product solution; and performing post-treatment to obtain a bromo-triazine product. According to the invention, the aluminum oxide loaded N, N-dimethylaminopyridine catalyst is synthesized, and the N, N-dimethylaminopyridine enables the reaction speed to be higher and the yield to be higher; nano aluminum oxide is adopted for loading, so that on one hand, dealkalization synthesis of bromotriazine is realized, and on the other hand, the reaction efficiency is accelerated; the continuous process realizes non-aqueous medium and low-temperature short-time reaction, so that hydrolysis is further avoided; the aluminum oxide loaded N, N-dimethylaminopyridine catalyst is high in activity and stability, the synthesis method is simplified, and the aluminum oxide loaded N, N-dimethylaminopyridine catalyst is suitable for industrial large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and in particular to a method for synthesizing bromotriazine. Background Art

[0002] Bromotriazine is a bromine / nitrogen synergistic flame retardant with excellent flame retardant effect and small usage. It is a new type of environmentally friendly flame retardant. Due to its good thermal stability, it is often used in plastic products such as ABS, PBT, and PC. Bromotriazine has high whiteness and good light resistance, making it an excellent upgraded alternative to decabromophenol.

[0003] At present, the mainstream production method of bromotriazine is to dissolve tribromophenol in an organic solvent and then react with sodium hydroxide solution, add triethylamine as a catalyst and then add cyanuric chloride. After a period of reaction, the product is washed in layers and crystallized and dried to obtain the product. Common problems are the by-product of cyanuric chloride hydrolysis, low raw material utilization and low yield.

[0004] For example, patent CN 117903073A uses metal oxides instead of sodium hydroxide to reduce the hydrolysis of cyanuric chloride, but reduces the reaction rate; patent CN 113214175A uses batch addition of cyanuric chloride and dropwise addition of liquid caustic soda to reduce the hydrolysis of cyanuric chloride, which is cumbersome and difficult to control. Patent CN 115785011A uses an online pH meter to control the pH of the reaction system to reduce the hydrolysis of cyanuric chloride. The process operation is complicated, and the accuracy of adjusting the pH with sodium hydroxide solution is difficult to control. In summary, we need a suitable method to fundamentally reduce the hydrolysis of cyanuric chloride to reduce by-products, while not affecting the reaction efficiency, and can improve the utilization rate of raw materials and increase the yield. Summary of the Invention

[0005] The purpose of the present application is to provide a method for synthesizing bromotriazine to solve the technical problems in the prior art that the bromotriazine synthesis system requires a large amount of base, cyanuric chloride is easily hydrolyzed, has many by-products and low yield.

[0006] To achieve the above object, the technical solution adopted in this application is: to provide a method for synthesizing bromotriazine, which specifically comprises the following steps: (1) Preparation of catalyst: adding nano-alumina to hydrochloric acid and stirring, and then reacting with 3-aminopropyltriethoxysilane for amination reaction to obtain amination alumina; performing carboxylation reaction of N,N-dimethylaminopyridine with succinic anhydride in a solvent to produce carboxylated N,N-dimethylaminopyridine; mixing the amination alumina, carboxylated N,N-dimethylaminopyridine, N,N-dimethylformamide and a condensing agent to react to obtain alumina-supported N,N-dimethylaminopyridine catalyst; (2) dissolving 2,4,6-tribromophenol in a chlorobenzene solution and adding magnesium oxide powder to obtain a tribromophenol slurry; dispersing cyanuric chloride in a chlorobenzene solution to obtain a cyanuric chloride slurry; (3) Filling a fixed bed reactor with alumina-supported N,N-dimethylaminopyridine catalyst, introducing tribromophenol slurry and cyanuric chloride slurry, heating to react, and obtaining a crude product solution; washing the crude product solution, distilling at atmospheric pressure, crystallizing, centrifuging, and drying to obtain a bromotriazine product; the reaction equation is as follows: .

[0007] In one embodiment, Step (1) The crystal form of the nano-alumina is γ-Al2O3, and the particle size of the nano-alumina is 50-80 nm.

[0008] In one embodiment, In step (1), the concentration of hydrochloric acid was 6 M, the stirring temperature was 60° C., and the stirring time was 2 h.

[0009] In one embodiment, Step (1) The mass ratio of nano-alumina to 3-aminopropyltriethoxysilane is 1:0.2-0.4, the solvent for the amination reaction is anhydrous ethanol, the reaction time is 4 h, and the reaction temperature is 80°C.

[0010] In one embodiment, Step (1) The mass ratio of N,N-dimethylaminopyridine to succinic anhydride is 1:1.2-1.5, the solvent for the carboxylation reaction is triethylamine, the reaction time is 12 h, and the reaction temperature is 80°C.

[0011] In one embodiment, The condensing agent in step (1) is a mixture of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a mass ratio of 1:1.

[0012] In one embodiment, In step (2), the mass ratio of 2,4,6-tribromophenol to chlorobenzene solution is 1:1.3-1.4, the molar ratio of 2,4,6-tribromophenol to magnesium oxide is 1:0.6-0.7, and the mass ratio of cyanuric chloride to chlorobenzene solution is 1:1.8-2.

[0013] In one embodiment, In step (3), the mass ratio of the cyanuric chloride slurry to the tribromophenol solution is 1:4.9-5.3.

[0014] In one embodiment, The temperature of step (iii) is 55-60°C.

[0015] In one embodiment, In step (3), the flow rate of the tribromophenol solution and the cyanuric chloride slurry is 20 ml / min.

[0016] The present application provides an alumina-supported N,N-dimethylaminopyridine catalyst. N,N-dimethylaminopyridine can catalyze hydroxyl compounds with large steric hindrance and low activity under mild conditions with a fast reaction speed and higher yield. The use of nano-alumina for support and the addition of magnesium oxide can replace strong bases to achieve de-alkalization synthesis of bromotriazine, reducing corrosion to equipment during synthesis. The absence of strong bases reduces the hydrolysis of cyanuric chloride, minimizes side reactions, improves product quality, and enhances thermal stability. On the other hand, nano-alumina has a large specific surface area and a strong loading capacity, which accelerates reaction efficiency. The continuous process realizes non-aqueous medium and low-temperature short-time reaction, further avoiding the occurrence of hydrolysis. The alumina-supported N,N-dimethylaminopyridine catalyst has high catalytic activity and stability, simplifies the synthesis method, and is suitable for industrial large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0018] Figure 1 This is the liquid phase diagram of the product obtained in Example 1; Figure 2 This is the thermogravimetric measurement diagram of the product obtained in Example 1; Figure 3 This is an electron microscope image of the alumina-supported N,N-dimethylaminopyridine catalyst in Example 1. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clear and understandable, this application is further described in detail. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0020] Example 1 A method for synthesizing bromotriazine specifically comprises the following steps: (I) Preparation of catalyst: 1 kg of nano-alumina with a particle size of 60 nm and a γ-crystalline form was added to an appropriate amount of hydrochloric acid (6 M) and stirred at 60 ° C for 2 h; then anhydrous ethanol and 0.3 kg of 3-aminopropyltriethoxysilane were added, and the amination reaction was carried out at 80 ° C for 4 h. After the end, it was washed with ethanol several times and vacuum dried at 110 ° C to remove the 3-aminopropyltriethoxysilane adsorbed on the surface to obtain ammoniated alumina; 1 kg of N, N-dimethylaminopyridine and 1.3 kg of succinic anhydride were added to triethylamine and carboxylated at 80 ° C for 12 h. The triethylamine was evaporated at normal pressure, and the remaining solid was washed with ice ether to remove the unreacted succinic anhydride. It was recrystallized with a mixed solvent of isopropyl alcohol / ethyl ether (volume ratio of 1:3) to obtain white crystalline carboxylated N, N-dimethylaminopyridine; 500 g of ammoniated alumina, 500 g of carboxylated N, N-dimethylaminopyridine, 1.1 1 kg of N,N-dimethylformamide, 275 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 275 g of N-hydroxysuccinimide were mixed and reacted for 20 h to prepare an alumina-supported N,N-dimethylaminopyridine catalyst; (2) Disperse 5 kg of 2,4,6-tribromophenol and 0.365 kg of magnesium oxide in 6.5 kg of chlorobenzene to obtain 11.86 kg of tribromophenol slurry; disperse 5 kg of cyanuric chloride in 9 kg of chlorobenzene to obtain 14 kg of cyanuric chloride slurry; (III) Fill a fixed bed reactor with 1 kg of alumina-supported N,N-dimethylaminopyridine catalyst, first pass 2 kg of tribromophenol slurry into the fixed bed reactor filled with the catalyst, collect the reaction liquid and enter the second fixed bed reactor, then add 10 kg of cyanuric chloride slurry at a flow rate of 20 ml / min, raise the temperature to 60 ° C for reaction, continue feeding the reaction for 2 hours, and collect the crude solution; wash the crude solution with 3% by mass concentration of dilute hydrochloric acid to wash away the residual magnesium oxide powder in the solution, distill at atmospheric pressure, crystallize, centrifuge, and dry to obtain the bromotriazine product 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine, such as Figure 1 As shown, the yield is 98.7% and the purity is 99.52%. Figure 2 As shown, 1% TGA thermal weight loss is 354 ℃.

[0021] Example 2 This embodiment differs from the embodiment in that, in step (1), the mass ratio of nano-alumina to 3-aminopropyltriethoxysilane is 1:0.2, and the remaining operations are the same, to obtain a bromotriazine product with a yield of 97.3%, a purity of 99.21%, and a 1% TGA thermal weight loss of 357°C.

[0022] Example 3 This embodiment differs from Example 1 in that, in step (1), the mass ratio of nano-alumina to 3-aminopropyltriethoxysilane is 1:0.4, and the remaining operations are the same, to obtain a bromotriazine product with a yield of 98.5%, a purity of 99.48%, and a 1% TGA thermal weight loss of 355°C.

[0023] Example 4 This embodiment differs from Example 1 in that, in step (1), the mass ratio of N,N-dimethylaminopyridine to succinic anhydride is 1:1.2, and the remaining operations are the same, to obtain a bromotriazine product with a yield of 98.6%, a purity of 99.4%, and a 1% TGA thermal weight loss of 355°C.

[0024] Example 5 This embodiment differs from Example 1 in that, in step (1), the mass ratio of N,N-dimethylaminopyridine to succinic anhydride is 1:1.5, and the remaining operations are the same, to obtain a bromotriazine product with a yield of 97.8%, a purity of 99.37%, and a 1% TGA thermal weight loss of 354°C.

[0025] Example 6 This embodiment differs from Example 1 in that in step (ii), the molar ratio of 2,4,6-tribromophenol to magnesium oxide is 1:0.7, and the remaining operations are the same to obtain a bromotriazine product with a yield of 97.8%, a purity of 99.40%, and a 1% TGA thermal weight loss of 359°C.

[0026] Example 7 This embodiment differs from Example 1 in that, in step (ii), the mass ratio of 2,4,6-tribromophenol to chlorobenzene solution is 1:1.4, the molar ratio of 2,4,6-tribromophenol to magnesium oxide is 1:0.7, and the mass ratio of cyanuric chloride to chlorobenzene solution is 1:2. The remaining operations are the same to obtain a bromotriazine product with a yield of 97.8%, a purity of 99.40%, and a 1% TGA thermal weight loss of 359°C.

[0027] Example 8 This embodiment differs from Example 1 in that, in step (iii), the mass ratio of cyanuric chloride slurry to tribromophenol solution is 1:4.9. The remaining operations are the same, and the bromotriazine product is obtained with a yield of 98.9%, a purity of 99.52%, and a 1% TGA thermal weight loss of 357°C.

[0028] Example 9 This embodiment differs from Example 1 in that, in step (iii), the mass ratio of cyanuric chloride slurry to tribromophenol solution is 1:5.3, and the remaining operations are the same to obtain a bromotriazine product with a yield of 98.9%, a purity of 99.39%, and a 1% TGA thermal weight loss of 353°C.

[0029] The present application provides a method for synthesizing bromotriazine, comprising the following steps: preparing an alumina-supported N,N-dimethylaminopyridine catalyst, filling an alumina-supported N,N-dimethylaminopyridine catalyst into a fixed bed reactor, introducing a tribromophenol solution and a cyanuric chloride slurry, heating the reactor to react, and obtaining a crude product solution; post-treating the crude product solution to obtain a bromotriazine product; the present application synthesizes an alumina-supported N,N-dimethylaminopyridine catalyst, which can catalyze large steric hindrance and low activity hydroxyl compounds under mild conditions, with a fast reaction speed and a higher yield; using nanoparticles to synthesize bromotriazine; the catalyst is catalyzed by alumina ... Nano-alumina loading, on the one hand, aluminum oxide and magnesium oxide can replace strong alkali to achieve de-alkalization synthesis of bromotriazine, reducing corrosion to equipment during synthesis; without using strong alkali, the hydrolysis of cyanuric chloride is reduced, the side reaction is extremely small, the quality of the product is improved, and the thermal stability is improved; on the other hand, nano-alumina has a large specific surface area and a strong loading capacity, which accelerates the reaction efficiency; the continuous process realizes non-aqueous medium and low-temperature short-time reaction, further avoiding the occurrence of hydrolysis; the alumina-loaded N,N-dimethylaminopyridine catalyst has high catalytic activity and high stability, simplifies the synthesis method, and is suitable for industrial large-scale production.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0031] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for synthesizing bromotriazine, characterized in that: The specific steps include: (1) Preparation of catalyst: adding nano-alumina to hydrochloric acid and stirring, and then performing an amination reaction with 3-aminopropyltriethoxysilane to prepare amination alumina; performing a carboxylation reaction of N,N-dimethylaminopyridine with succinic anhydride in a solvent to produce carboxylated N,N-dimethylaminopyridine; mixing the amination alumina, carboxylated N,N-dimethylaminopyridine, N,N-dimethylformamide and a condensing agent to react to prepare an alumina-supported N,N-dimethylaminopyridine catalyst; (2) dissolving 2,4,6-tribromophenol in a chlorobenzene solution and adding magnesium oxide powder to obtain a tribromophenol slurry; dispersing cyanuric chloride in a chlorobenzene solution to obtain a cyanuric chloride slurry; (3) Filling the alumina-supported N,N-dimethylaminopyridine catalyst into a fixed-bed reactor, introducing tribromophenol solution and cyanuric chloride slurry, heating to react, and obtaining a crude product solution; washing the crude product solution, distilling at atmospheric pressure, crystallizing, centrifuging, and drying to obtain a bromotriazine product.

2. The method for synthesizing a bromotriazine according to claim 1, wherein The crystal form of the nano-alumina in step (1) is γ-Al2O3, and the particle size of the nano-alumina is 50-80 nm.

3. The method for synthesizing a bromotriazine according to claim 1, wherein: In step (1), the concentration of hydrochloric acid is 6 M, the stirring temperature is 60° C., and the stirring time is 2 h.

4. The method for synthesizing a bromotriazine according to claim 1, wherein: In step (1), the mass ratio of the nano-alumina to 3-aminopropyltriethoxysilane is 1:0.2-0.4, the solvent for the amination reaction is anhydrous ethanol, the reaction time is 4 h, and the reaction temperature is 80°C.

5. The method for synthesizing bromotriazine according to claim 1, wherein: In step (1), the mass ratio of N,N-dimethylaminopyridine to succinic anhydride is 1:1.2-1.5, the solvent for the carboxylation reaction is triethylamine, the reaction time is 12 h, and the reaction temperature is 80°C.

6. The method for synthesizing bromotriazine according to claim 1, wherein: The condensing agent in step (1) is a mixture of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide, with a mixing mass ratio of 1:

1.

7. The method for synthesizing a bromotriazine according to claim 1, wherein: In step (ii), the mass ratio of the 2,4,6-tribromophenol to the chlorobenzene solution is 1:1.3-1.4, the molar ratio of the 2,4,6-tribromophenol to magnesium oxide is 1:0.6-0.7, and the mass ratio of the cyanuric chloride to the chlorobenzene solution is 1:1.8-2.

8. The method for synthesizing bromotriazine according to claim 1, wherein: The mass ratio of the cyanuric chloride slurry to the tribromophenol solution in step (iii) is 1:4.9-5.

3.

9. The method for synthesizing bromotriazine according to claim 1, wherein: The temperature of the heating in step (3) is 55-60°C.

10. The method for synthesizing bromotriazine according to claim 1, wherein: The flow rate of the tribromophenol solution and cyanuric chloride slurry in step (iii) is 20 ml / min.

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