Preparation method of bromo-triazine for improving reaction selectivity
By using multi-walled carbon nanotubes to support amine catalysts and magnesium oxide, combined with azeotropic desolvation technology, the problem of poor reaction selectivity in the preparation of bromotriazine was solved, and high yield and high purity of bromotriazine were achieved.
Patent Information
- Application Number
- CN202610501858.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-16
- Publication Date
- 2026-05-19
AI Technical Summary
In existing methods for preparing bromotriazine, the reaction selectivity is poor, leading to a decrease in the yield and purity of bromotriazine. Furthermore, traditional methods are prone to hydrolysis or partial substitution reactions.
Using amine compounds supported on multi-walled carbon nanotubes as catalysts, combined with magnesium oxide, and controlling the reaction between tribromophenol and cyanuric chloride, an azeotropic desolvation technique was employed to improve reaction selectivity and efficiency.
This improved the yield and purity of bromotriazine, reduced side reactions, and enhanced the selectivity and efficiency of the reaction.
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Abstract
Description
Technical Field
[0001] This application relates to the field of flame retardant products, and in particular to a method for preparing a brominated triazine with improved reaction selectivity. Background Technology
[0002] Bromotriazine, as an important organic compound, has wide applications in flame retardants, pharmaceutical intermediates, and many other fields. With the continuous development of the chemical industry, the demand for bromotriazine is increasing, and its preparation technology is constantly evolving. Efficient, environmentally friendly, and highly selective preparation methods are of great significance for improving the production quality and efficiency of bromotriazine, reducing production costs, and promoting the development of related industries.
[0003] In the traditional preparation of bromotriazine, a common method is to directly react phenol with bromine, and then react the resulting tribromophenol with raw materials such as cyanuric chloride to generate bromotriazine. During the condensation reaction of tribromophenol and cyanuric chloride to form bromotriazine, the three chlorine atoms of cyanuric chloride are highly reactive. They not only react with tribromophenol but also readily undergo hydrolysis with trace amounts of moisture in the system. Improper reaction control can easily lead to hydrolysis or partial substitution, resulting in a decrease in the yield and purity of the target product, bromotriazine. Summary of the Invention
[0004] In order to improve the reaction selectivity in the existing brominated triazine preparation process, this application provides a method for preparing brominated triazine with improved reaction selectivity.
[0005] This application provides a method for preparing bromotriazine with improved reaction selectivity, which adopts the following technical solution: A method for preparing bromotriazine with improved reaction selectivity includes the following specific steps: adding phenol, water, and dichloromethane to a reaction vessel, then adding hydrogen peroxide dropwise to the reaction system, followed by adding bromine dropwise to the reaction system to obtain a reaction solution, treating the reaction solution with sodium sulfite and washing it with water to separate the organic phase containing tribromophenol, mixing the organic phase containing tribromophenol with magnesium oxide, a catalyst, and cyanuric chloride to obtain a crude solution, washing the crude solution and mixing it with process water, heating it to an azeotropic solvent, and finally crystallizing and drying to obtain bromotriazine; wherein the catalyst is an amine compound supported on multi-walled carbon nanotubes.
[0006] By adopting the above technical solution, this application utilizes the tubular structure of multi-walled carbon nanotubes to load amine compounds. Leveraging the loading effect of a solid catalyst, it reduces the opportunity for free amine compounds to directly contact water molecules, allowing the three chlorine atoms of cyanuric chloride to be replaced stepwise and orderly by tribromophenol molecules, preventing the reaction from stopping at intermediate stages and reducing the probability of side reactions. Carbon nanotubes have a large specific surface area and strong adsorption capacity, enabling the enrichment of tribromophenol around the catalyst, increasing the concentration of the active site tribromophenol reactant, and improving reaction efficiency. In the mixed reaction of tribromophenol with magnesium oxide, catalyst, and cyanuric chloride, fixing the amine compounds in carbon nanotubes reduces the free dispersion of amine compounds, isolates the active site, and reduces the phenomenon of amine compounds entering the aqueous phase and promoting hydrolysis. Through multiple effects, the reaction rate of the main reaction can be increased, while the occurrence of side reactions is suppressed, improving the yield and purity of the bromotriazine product.
[0007] Meanwhile, in the reaction process of tribromophenol and cyanuric chloride, magnesium oxide is used instead of liquid alkali in the traditional process to avoid excessive local alkalinity that could lead to hydrolysis of cyanuric chloride. Magnesium oxide can gently neutralize acid, inhibit side reactions, and improve reaction selectivity.
[0008] Preferably, the method for loading amine compounds onto multi-walled carbon nanotubes includes the following specific steps: Multi-walled carbon nanotubes were passivated with nitric acid and then mixed with N,N-dimethylformamide. Under the protection of nitrogen, a mixture of N,N-dimethylformamide and amine compounds was added, and the mixture was heated and stirred to react. After filtration and vacuum drying, multi-walled carbon nanotubes loaded with amine compounds were obtained, which served as a catalyst.
[0009] By adopting the above technical solution, multi-walled carbon nanotubes treated with nitric acid can exhibit good dispersibility in N,N-dimethylformamide, promoting the uniform distribution of active sites of amine compounds on the support and improving the reaction rate and uniformity.
[0010] Preferably, the amine compound is one of dimethylamine, N,N-dimethylaminopyridine, and ethylenediamine.
[0011] By adopting the above technical solutions, dimethylamine has a high reaction rate, N,N-dimethylaminopyridine has a high reaction selectivity, and ethylenediamine has good catalytic stability. Dimethylamine, N,N-dimethylaminopyridine, and ethylenediamine can combine with carbon nanotubes and can uniformly contact the reactants, thereby improving reaction efficiency and reaction selectivity.
[0012] Preferably, the mass ratio of the multi-walled carbon nanotubes, N,N-dimethylformamide and amine compounds is 1:(0.5-0.8):(0.1-0.3).
[0013] Preferably, the heating temperature is 80-90℃.
[0014] Preferably, the mass ratio of phenol to water and dichloromethane is 1:(0.8-1.2):(9-11), and the mass ratio of phenol to bromine and hydrogen peroxide is 1:(2.5-2.8):(2.1-2.4).
[0015] Preferably, the molar ratio of tribromophenol to magnesium oxide and cyanuric chloride is 1:(0.6-0.7):(0.4-0.6); and the mass ratio of cyanuric chloride to catalyst is 1:(0.05-0.08).
[0016] Preferably, the reaction temperature of tribromophenol with magnesium oxide, catalyst, and cyanuric chloride is 60-80℃.
[0017] Preferably, the azeotropic desolvation temperature is 40-45℃ and the time is 8-10 hours.
[0018] By adopting the above technical solution, the azeotropic properties can be used to remove dichloromethane from the organic phase and promote the precipitation of the product. The long-term slow desolvation is beneficial to the formation of regular crystal forms and improves the purity of the product.
[0019] In summary, this application has the following beneficial effects: 1. This application utilizes multi-walled carbon nanotubes to support amine compounds. Carbon nanotubes have a large specific surface area and strong adsorption capacity, reducing the opportunity for free amine compounds in the organic phase to directly contact water molecules. Tribromophenol is enriched around the catalyst, increasing the concentration of the active site and thus improving reaction efficiency. In the mixed reaction of tribromophenol with magnesium oxide, catalyst, and cyanuric chloride, immobilizing the amine compounds on carbon nanotubes can increase the main reaction rate, suppress side reactions, and improve the yield and purity of the bromotriazine product.
[0020] 2. In this application, multi-walled carbon nanotubes are pretreated with nitric acid, which promotes the uniform distribution of active sites of amine compounds on the support, thereby improving the reaction rate and uniformity. Simultaneously, dimethylamine, N,N-dimethylaminopyridine, and ethylenediamine are used as amine compounds, which can combine with multi-walled carbon nanotubes, ensuring uniform contact with the reactants and improving reaction efficiency and selectivity. Detailed Implementation
[0021] The present application will be further described in detail below with reference to the embodiments.
[0022] All raw materials used in the examples are commercially available.
[0023] Catalyst preparation example Preparation Example 1 The preparation method of the catalyst includes the following specific steps: Multi-walled carbon nanotubes (MWC nanotubes) were passivated by immersion in nitric acid for 24 hours, resulting in an average outer diameter of 10 nm and an average inner diameter of 5 nm. After washing and drying, passivated MWC nanotubes were obtained. The passivated MWC nanotubes were mixed with half of N,N-dimethylformamide and stirred until homogeneous. Under nitrogen protection, the remaining mixture of N,N-dimethylformamide and an amine compound was added. The mass ratio of MWC nanotubes, N,N-dimethylformamide, and the amine compound was 1:0.7:0.2. The amine compound was N,N-dimethylaminopyridine. The mixture was heated to 85 °C and stirred for 72 h. After filtration, washing, and vacuum drying, the amine compound supported on the MWC nanotubes was obtained as a catalyst.
[0024] Preparation Example 2 The difference between Preparation Example 2 and Preparation Example 1 is that the mass ratio of multi-walled carbon nanotubes, N,N-dimethylformamide and amine compounds in the catalyst raw materials is 1:0.5:0.3.
[0025] Preparation Example 3 The difference between Preparation Example 3 and Preparation Example 1 is that the mass ratio of multi-walled carbon nanotubes, N,N-dimethylformamide and amine compounds in the catalyst raw materials is 1:0.8:0.1.
[0026] Preparation Example 4 The difference between Preparation Example 4 and Preparation Example 1 is that the amine compound in the catalyst feedstock is ethylenediamine. Example
[0027] Example 1 This embodiment provides a method for preparing bromotriazine with improved reaction selectivity, including the following specific steps: S1: Phenol, water, and dichloromethane are added to a reaction vessel. The mass ratio of phenol to water and dichloromethane is 1:1:10. Hydrogen peroxide is added dropwise to the reaction system while stirring, and the reaction is carried out for 30 minutes. Then, bromine is added dropwise to the reaction system and mixed. The reaction is carried out at 50°C for 30 minutes. The mass ratio of phenol to bromine and hydrogen peroxide is 1:2.6:2.3. The reaction solution is obtained. The reaction solution is washed with sodium sulfite and water. The mass ratio of sodium sulfite to water is 1:1. The organic phase containing tribromophenol is separated.
[0028] S2: The organic phase containing tribromophenol was mixed with magnesium oxide, catalyst, and cyanuric chloride and reacted at 70°C. The catalyst was derived from Preparation Example 1. The molar ratio of tribromophenol to magnesium oxide and cyanuric chloride was 1:0.65:0.5, and the mass ratio of cyanuric chloride to catalyst was 1:0.07, resulting in a crude solution. The crude solution was washed with 3% (w / w) dilute hydrochloric acid and then mixed with process water at a mass ratio of 1:1. The process water was deionized water. The mixture was heated to 43°C for azeotropic desolvation for 9 hours. Finally, the mixture was crystallized and dried to obtain bromotriazine.
[0029] Example 2 The difference between Example 2 and Example 1 is that the mass ratio of phenol, bromine, and hydrogen peroxide in the preparation method of bromotriazine is 1:2.5:2.1.
[0030] Example 3 The difference between Example 3 and Example 1 is that the mass ratio of phenol, bromine, and hydrogen peroxide in the preparation method of bromotriazine is 1:2.8:2.4.
[0031] Example 4 The difference between Example 4 and Example 1 is that in the preparation method of bromotriazine, the molar ratio of tribromophenol to magnesium oxide and cyanuric chloride is 1:0.6:0.4, and the mass ratio of cyanuric chloride to catalyst is 1:0.05.
[0032] Example 5 The difference between Example 5 and Example 1 is that in the preparation method of bromotriazine, the molar ratio of tribromophenol to magnesium oxide and cyanuric chloride is 1:0.7:0.6, and the mass ratio of cyanuric chloride to catalyst is 1:0.08.
[0033] Example 6 The difference between Example 6 and Example 1 is that the catalyst in the preparation method of bromotriazine is derived from Preparation Example 2.
[0034] Example 7 The difference between Example 7 and Example 1 is that the catalyst in the preparation method of bromotriazine is derived from Preparation Example 3.
[0035] Example 8 The difference between Example 8 and Example 1 is that the catalyst in the preparation method of bromotriazine is derived from Preparation Example 4.
[0036] Comparative Example Comparative Example 1 A method for preparing bromotriazine with improved reaction selectivity includes the following specific steps: S1: Phenol, water, and dichloromethane are added to a reaction vessel. The mass ratio of phenol to water and dichloromethane is 1:1:10. Hydrogen peroxide is added dropwise to the reaction system while stirring, and the reaction is carried out for 30 minutes. Then, bromine is added dropwise to the reaction system and mixed. The reaction is carried out at 50°C for 30 minutes. The mass ratio of phenol to bromine and hydrogen peroxide is 1:2.6:2.3. The reaction solution is obtained. The reaction solution is washed with sodium sulfite and water. The mass ratio of sodium sulfite to water is 1:1. The organic phase containing tribromophenol is separated.
[0037] S2: The organic phase containing tribromophenol was mixed with magnesium oxide, catalyst, and cyanuric chloride and reacted at 70°C. The catalyst was derived from Preparation Example 1. The molar ratio of tribromophenol to magnesium oxide and cyanuric chloride was 1:0.65:0.5, and the mass ratio of cyanuric chloride to catalyst was 1:0.07. A crude solution was obtained. The crude solution was washed with 3% dilute hydrochloric acid, crystallized, and dried to obtain bromotriazine.
[0038] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that, in the preparation method of bromotriazine, an equal amount of liquid alkali with a mass concentration of 32% is used instead of magnesium oxide.
[0039] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that an equal amount of N,N-dimethylaminopyridine was used instead of a catalyst in the preparation method of bromotriazine.
[0040] Performance testing According to the preparation methods of bromotriazine provided in Examples 1-8 and Comparative Examples 1-3 of this application, the following performance tests were performed, and the specific test results are shown in Table 1.
[0041] Detection methods I. Purity Test The purity of the bromotriazine prepared in this application was tested using a high-performance liquid chromatograph (SHIMADZU, UV-Vis detector), and the product yield was calculated.
[0042] II. Solvent Residue Test A gas chromatograph equipped with an FID detector and headspace sampler was used. 0.5 g of sample was placed in a headspace vial, dissolved in 5 mL of N,N-dimethylformamide, and sealed. The vial was placed in the headspace sampler and heated to equilibrium. Headspace gas was then injected into the gas chromatograph. The residual amount of dichloromethane in the sample was calculated using the external standard method, with the peak area of dichloromethane standard as the benchmark.
[0043] Table 1: Performance Test Results Data Table
[0044] The performance test results show that the bromotriazine prepared by the preparation process used in this application has high purity and yield, while the solvent residue is reduced.
[0045] A comparison of Comparative Examples 1-3 and Example 1 reveals that the crude solution obtained in Comparative Example 1, without azeotropic solvent removal, resulted in a significant increase in solvent content and a decrease in purity in the prepared bromotriazine, as indicated by performance testing. In Comparative Example 2, conventional liquid alkali was used instead of magnesium oxide. Performance testing showed a significant decrease in the purity of the prepared bromotriazine, further demonstrating that conventional use of liquid alkali in the preparation of bromotriazine can lead to side reactions, thereby reducing the purity of the bromotriazine product. In Comparative Example 3, a conventional amine catalyst was used without multi-walled carbon nanotubes as a support. Performance testing showed a decrease in both the purity and yield of the bromotriazine, further illustrating that this application utilizes the tubular structure of multi-walled carbon nanotubes to load amine compounds, enriching tribromophenol around the catalyst while allowing less amine compound to disperse freely, isolating the active center, reducing the entry of amine compounds into the aqueous phase and promoting hydrolysis, thereby increasing the reaction rate of the main reaction, suppressing side reactions, and improving the yield and purity of the bromotriazine product.
[0046] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.
Claims
1. A method for preparing bromotriazine with improved reaction selectivity, characterized in that, The specific steps include: adding phenol, water, and dichloromethane to a reaction vessel, then adding hydrogen peroxide dropwise to the reaction system, followed by adding bromine dropwise to the reaction system to mix and react, obtaining a reaction solution, treating the reaction solution with sodium sulfite and washing with water to separate the organic phase containing tribromophenol, mixing the organic phase containing tribromophenol with magnesium oxide, a catalyst, and cyanuric chloride to obtain a crude solution, washing the crude solution and mixing it with process water, heating to azeotropically desolvate, and finally crystallizing and drying to obtain bromotriazine; the catalyst is an amine compound supported on multi-walled carbon nanotubes.
2. The method for preparing brominated triazine with improved reaction selectivity according to claim 1, characterized in that, The method for loading amine compounds onto multi-walled carbon nanotubes includes the following specific steps: Multi-walled carbon nanotubes were passivated with nitric acid and then mixed with N,N-dimethylformamide. Under the protection of nitrogen, a mixture of N,N-dimethylformamide and amine compounds was added, and the mixture was heated and stirred to react. After filtration and vacuum drying, multi-walled carbon nanotubes loaded with amine compounds were obtained, which served as a catalyst.
3. The method for preparing bromotriazine with improved reaction selectivity according to claim 2, characterized in that, The amine compound is one of dimethylamine, N,N-dimethylaminopyridine, and ethylenediamine.
4. The method for preparing brominated triazine with improved reaction selectivity according to claim 2, characterized in that, The mass ratio of the multi-walled carbon nanotubes, N,N-dimethylformamide, and amine compounds is 1:(0.5-0.8):(0.1-0.3).
5. The method for preparing bromotriazine with improved reaction selectivity according to claim 2, characterized in that, The heating temperature is 80-90℃.
6. The method for preparing bromotriazine with improved reaction selectivity according to claim 1, characterized in that, The mass ratio of phenol to water and dichloromethane is 1:(0.8-1.2):(9-11), and the mass ratio of phenol to bromine and hydrogen peroxide is 1:(2.5-2.8):(2.1-2.4).
7. The method for preparing bromotriazine with improved reaction selectivity according to claim 1, characterized in that, The molar ratio of tribromophenol to magnesium oxide and cyanuric chloride is 1:(0.6-0.7):(0.4-0.6); the mass ratio of cyanuric chloride to catalyst is 1:(0.05-0.08).
8. The method for preparing bromotriazine with improved reaction selectivity according to claim 7, characterized in that, The reaction temperature of tribromophenol with magnesium oxide, catalyst, and cyanuric chloride is 60-80℃.
9. The method for preparing bromotriazine with improved reaction selectivity according to claim 1, characterized in that, The azeotropic desolvation temperature is 40-45℃, and the time is 8-10 hours.