Preparation process of ethylene bis-tetrabromophthalimide with high thermal stability
By using water as a medium and adding ferric chloride and iodine catalysts in the preparation of ethylene bis(tetrabromophthalimide), the bromination reaction temperature was controlled, and a chelating agent was used to remove metal ion impurities. This solved the problems of local overheating and debromination in the bromination reaction, and improved the thermal stability and purity of the product.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHOUGUANG LONGHAO CHEM CO LTD
- Filing Date
- 2026-04-17
- Publication Date
- 2026-07-03
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This application relates to the field of flame retardant materials, and in particular to a preparation process for a highly thermally stable ethylene bis(tetrabromophthalimide). Background Technology
[0002] In recent years, commonly used flame retardants both domestically and internationally include inorganic flame retardants, halogenated flame retardants, halogen-free flame retardants, and nano-flame retardants. Although halogenated flame retardants have drawbacks such as high smoke production and the generation of corrosive gases, their undeniably excellent flame-retardant properties keep researchers both at home and abroad enthusiastic about developing new products. Among halogenated flame retardants, chlorine-based flame retardants produce even more smoke, while bromine-based flame retardants, in addition to having significantly better flame-retardant properties than chlorine- and bromine-based flame retardants, also have advantages such as good versatility and good hydrolysis resistance.
[0003] Ethylene bis(tetrabromophthalimide) is an excellent flame retardant with superior light and thermal stability and electrical properties, making it particularly suitable for various resins and elastomers processed at high temperatures, as well as for applications in wires, cables, and electronic and electrical equipment. In the conventional synthesis of ethylene bis(tetrabromophthalimide), the exothermic bromination reaction can lead to localized overheating, which easily causes debromination, resulting in the escape of HBr and a lower final bromine content, thus affecting the flame retardant efficiency. Summary of the Invention
[0004] To improve upon the shortcomings of existing processes for preparing ethylene bis(tetrabromophthalimide), this application provides a process for preparing ethylene bis(tetrabromophthalimide) with high thermal stability.
[0005] This application provides a process for preparing ethylene bis(tetrabromophthalimide) with high thermal stability, which adopts the following technical solution: A process for preparing a highly thermally stable ethylene bis(tetrabromophthalimide) includes the following specific steps: phthalic anhydride and ethylenediamine are mixed in water, heated to react, and centrifuged and dried to obtain an intermediate; the intermediate is mixed with bromine, fuming sulfuric acid, and a catalyst to obtain a reaction solution, heated to react, then deacidified, washed with water, and dried to obtain ethylene bis(tetrabromophthalimide); the catalyst is a complex of ferric chloride and iodine; deacidification involves distilling the reaction solution, cooling and filtering to obtain the reaction product, washing with water and drying, and then aging to obtain ethylene bis(tetrabromophthalimide).
[0006] By employing the above technical solution and using water as the reaction medium instead of organic solvents, pollution can be reduced and product purity improved. First, an ethylene bis(phthalimide) intermediate is synthesized from phthalic anhydride and ethylenediamine. The imidization reaction yields a structurally stable intermediate, reducing the occurrence of side reactions in the subsequent bromination reaction. Adding a catalyst to the reaction system of the intermediate with bromine and fuming sulfuric acid lowers the activation energy of the bromination reaction, reduces the instantaneous and intense exothermic reaction caused by excessively high local bromine concentrations, and lowers the temperature of the main reaction, reducing the high temperatures that lead to debromination reactions, thereby reducing the escape of HBr and the loss of bromine. Fuming sulfuric acid oxidizes bromide anions to bromine and simultaneously oxidizes the amine byproducts produced in the initial imidization reaction, thus improving product purity. Ferric chloride and iodine work synergistically; iodine reacts with bromine to form iodine bromide intermediate, efficiently transferring bromine. Simultaneously, ferric chloride binds to the intermediate, promoting the bromination reaction of the benzene ring and reducing the chance of free and accumulated bromide ions in the system and causing side reactions. The reaction solution is distilled to remove acid, cooled, and then filtered to obtain a solid product. This process separates the product from the strongly acidic environment and reduces the occurrence of side reactions. Thermal aging removes impurities that volatilize in the low-temperature region, improving product purity.
[0007] The combination of ferric chloride and iodine can lower the bromination reaction temperature, balance the concentration of bromide ions, reduce overheating caused by excessively high local reactant concentrations, and reduce debromination and HBr escape caused by thermal decomposition. Simultaneously, using ferric chloride as a catalyst improves reaction efficiency, resulting in a white appearance for the prepared ethylenebistetrabromophthalimide, thus reducing the yellowing problem of products prepared by conventional processes.
[0008] Preferably, the mass ratio of phthalic anhydride to ethylenediamine is 1:(3.5-5.5), and the mass ratio of the intermediate to bromine, fuming sulfuric acid, and catalyst is 1:(0.45-0.5):(0.1-0.2):(0.03-0.05).
[0009] Preferably, the mixture is mixed in water and heated to a reaction temperature of 75-105℃.
[0010] Preferably, the intermediate is mixed with bromine, fuming sulfuric acid and catalyst, and the reaction is heated to a temperature of 130-150℃.
[0011] Preferably, the aging temperature is 250-280℃.
[0012] Preferably, a chelating agent is added to the reaction solution before filtration and the mixture is reacted, wherein the mass ratio of the chelating agent to the reaction solution is (0.01-0.02):1.
[0013] By adopting the above technical solution, the addition of chelating agents can complex iron ions and other metal ions after the reaction, forming stable complexes, thereby removing iron ions and other metal ion impurities, reducing the oxidative degradation of the product by residual metal ions, reducing product decomposition and discoloration, and improving product purity.
[0014] Preferably, the chelating agent is one of aminotrimethylenephosphonic acid and ethylenediaminetetraacetic acid.
[0015] By adopting the above technical solution and using aminotrimethylenephosphonic acid and ethylenediaminetetraacetic acid as chelating agents, it can have good complexing ability in acidic reaction liquid system. Aminotrimethylenephosphonic acid also has good high temperature stability, which enhances the removal effect of chelating agents on metal ions and improves product purity.
[0016] In summary, this application has the following beneficial effects: 1. Because this application uses water as a medium instead of organic solvents, it can reduce pollution and improve product purity. A structurally stable intermediate is first synthesized via phthalic anhydride and ethylenediamine, reducing the occurrence of side reactions caused by subsequent high temperatures. Adding a catalyst to the reaction system of the intermediate with bromine and fuming sulfuric acid can lower the activation energy of the bromination reaction, reduce the instantaneous and violent exothermic phenomenon caused by excessively high local bromine concentrations, lower the temperature of the main reaction, reduce the high-temperature phenomena in the reaction system that lead to debromination reactions, and reduce the escape of HBr and the loss of bromine.
[0017] 2. In this application, ferric chloride and iodine are used as catalysts to lower the bromination reaction temperature, balance the concentration of bromide ions, reduce overheating caused by excessively high local reactant concentrations, and reduce debromination and HBr escape caused by thermal decomposition. Simultaneously, the use of ferric chloride as a catalyst promotes the white appearance of the prepared ethylenebistetrabromophthalimide, reducing the yellowing problem of products prepared by conventional processes. Detailed Implementation
[0018] The present application will be further described in detail below with reference to the embodiments.
[0019] All raw materials used in the examples are commercially available. Example Example 1
[0020] This embodiment provides a process for preparing ethylene bis(tetrabromophthalimide) with high thermal stability, including the following specific steps: Phthalic anhydride and ethylenediamine were mixed in water at a mass ratio of 1:4.5 and heated to 90°C for 9 hours. After the reaction, the mixture was centrifuged and dried to obtain an intermediate. The intermediate was then mixed with bromine, fuming sulfuric acid, and a catalyst at a mass ratio of 1:0.48:0.15:0.04. The catalyst was a complex of ferric chloride and iodine at a mass ratio of 1:1. The resulting reaction solution was heated to 140°C for 8 hours. After the reaction, the reaction solution was distilled to remove acid, cooled to room temperature, poured into water, filtered, and the resulting product was washed with water, dried, and then aged at 270°C for 30 minutes to obtain ethylenebistetrabromophthalimide.
[0021] Example 2
[0022] The difference between Example 2 and Example 1 is that the mass ratio of phthalic anhydride to ethylenediamine is 1:3.5.
[0023] Example 3 The difference between Example 3 and Example 1 is that the mass ratio of phthalic anhydride to ethylenediamine is 1:5.5.
[0024] Example 4 The difference between Example 4 and Example 1 is that the mass ratio of the intermediate to bromine, fuming sulfuric acid and catalyst is 1:0.45:0.1:0.03.
[0025] Example 5 The difference between Example 5 and Example 1 is that the mass ratio of the intermediate to bromine, fuming sulfuric acid and catalyst is 1:0.5:0.2:0.05.
[0026] Example 6 A process for preparing a highly thermally stable ethylene bis(tetrabromophthalimide) includes the following specific steps: Phthalic anhydride and ethylenediamine were mixed in water at a mass ratio of 1:4.5 and heated to 75°C for 10 hours. After the reaction, the mixture was centrifuged and dried to obtain an intermediate. The intermediate was then mixed with bromine, fuming sulfuric acid, and a catalyst at a mass ratio of 1:0.48:0.15:0.04. The catalyst was a complex of ferric chloride and iodine at a mass ratio of 1:1. The resulting reaction solution was heated to 150°C for 6 hours. After the reaction, the reaction solution was distilled to remove acid, cooled to room temperature, poured into water, and filtered to obtain the reaction product. The reaction product was washed with water, dried, and then aged at 270°C for 30 minutes to obtain ethylenebistetrabromophthalimide.
[0027] Example 7 A process for preparing a highly thermally stable ethylene bis(tetrabromophthalimide) includes the following specific steps: Phthalic anhydride and ethylenediamine were mixed in water at a mass ratio of 1:4.5 and heated to 105°C for 8 hours. After the reaction, the mixture was centrifuged and dried to obtain an intermediate. The intermediate was then mixed with bromine, fuming sulfuric acid, and a catalyst at a mass ratio of 1:0.48:0.15:0.04. The catalyst was a complex of ferric chloride and iodine at a mass ratio of 1:1. The resulting reaction solution was heated to 130°C for 9 hours. After the reaction, the reaction solution was distilled to remove acid, cooled to room temperature, poured into water, filtered, and the resulting product was washed with water, dried, and then aged at 270°C for 30 minutes to obtain ethylenebistetrabromophthalimide.
[0028] Example 8 A process for preparing a highly thermally stable ethylene bis(tetrabromophthalimide) includes the following specific steps: Phthalic anhydride and ethylenediamine were mixed in water at a mass ratio of 1:4.5 and heated to 90°C for 9 hours. After the reaction, the mixture was centrifuged and dried to obtain an intermediate. The intermediate was then mixed with bromine, fuming sulfuric acid, and a catalyst at a mass ratio of 1:0.48:0.15:0.04. The catalyst was a complex of ferric chloride and iodine at a mass ratio of 1:1. The resulting reaction solution was heated to 140°C for 8 hours. After the reaction, the solution was distilled to remove acid, cooled to room temperature, poured into water, filtered, and the reaction product was obtained. The product was washed with water and dried to prepare ethylenebis(tetrabromophthalimide).
[0029] Example 9 A process for preparing a highly thermally stable ethylene bis(tetrabromophthalimide) includes the following specific steps: Phthalic anhydride and ethylenediamine were mixed in water at a mass ratio of 1:4.5 and heated to 90°C for 9 hours. After the reaction, the mixture was centrifuged and dried to obtain an intermediate. The intermediate was then mixed with bromine, fuming sulfuric acid, and a catalyst at a mass ratio of 1:0.48:0.15:0.04. The catalyst was a complex of ferric chloride and iodine at a mass ratio of 1:1. The resulting reaction solution was heated to 140°C for 8 hours. After the reaction, the reaction solution was distilled to remove acid, cooled to room temperature, and poured into water. A chelating agent, aminotrimethylenephosphonic acid, was added and mixed for 30 minutes. The chelating agent was 0.01:1 in mass ratio to the reaction solution. The mixture was filtered to obtain the reaction product, which was then washed with water, dried, and aged at 270°C for 30 minutes to obtain ethylenebistetrabromophthalimide.
[0030] Example 10 The difference between Example 10 and Example 9 is that the chelating agent in the preparation process of ethylene bis(tetrabromophthalimide) is ethylenediaminetetraacetic acid.
[0031] Example 11 The difference between Example 11 and Example 9 is that the mass ratio of chelating agent to reaction solution in the preparation process of ethylene bis(tetrabromophthalimide) is 0.02:1.
[0032] Comparative Example Comparative Example 1 A process for preparing ethylene bis(tetrabromophthalimide) includes the following specific steps: Phthalic anhydride was mixed with fuming sulfuric acid and a catalyst, heated to 75°C, and bromine was added dropwise. The mass ratio of phthalic anhydride to fuming sulfuric acid, catalyst, and bromine was 1:5:0.05:1.5. The mixture was heated to 140°C and reacted for 8 hours. The catalyst was a complex of ferric chloride and iodine, with a mass ratio of ferric chloride to iodine of 1:1. After the reaction was completed, the mixture was cooled, filtered, washed, and dried to obtain tetrabromophthalic anhydride. Tetrabromophthalic anhydride, xylene, and propionic acid were mixed and stirred, heated to 90°C, and ethylenediamine was added dropwise. The mass ratio of tetrabromophthalic anhydride, xylene, propionic acid, and ethylenediamine was 1:3:1:0.1. The mixture was reacted for 9 hours, cooled, filtered, washed, and dried to obtain ethylenebistetrabromophthalimide.
[0033] Comparative Example 2 A process for preparing a highly thermally stable ethylene bis(tetrabromophthalimide) includes the following specific steps: Phthalic anhydride was mixed with ethylenediamine, toluene, and propionic acid in a mass ratio of 1:4.5:3:1. The mixture was heated to 90°C and reacted for 9 hours. After the reaction, the mixture was centrifuged and dried to obtain an intermediate. The intermediate was then mixed with bromine, fuming sulfuric acid, and a catalyst in a mass ratio of 1:0.48:0.15:0.04. The catalyst was a complex of ferric chloride and iodine in a mass ratio of 1:1. The resulting reaction solution was heated to 140°C and reacted for 8 hours. After the reaction, the reaction solution was distilled to remove acid, cooled to room temperature, poured into water, filtered, and the reaction product was obtained. The reaction product was washed with water, dried, and then aged at 270°C for 30 minutes to obtain ethylenebistetrabromophthalimide.
[0034] Performance testing Based on the ethylene bis(tetrabromophthalimide) provided in Examples 1-11 and Comparative Examples 1-2 of this application, the appearance color of the product was observed and the following performance tests were performed. The specific test results are shown in Table 1.
[0035] Detection methods I. Determination of Bromine Content The bromine content in the ethylene bis(tetrabromophthalimide) prepared in this application was determined according to the standard GB / T 9872-1998 "Determination of bromine and chlorine content in rubber and rubber products by oxygen flask combustion method".
[0036] II. Purity and Yield High performance liquid chromatography (HPLC) was used with a mobile phase of V(acetonitrile):V(water) = 8:2, a wavelength of 240 nm, a column temperature of 25 ℃, and an ODSC18 column with L = 15 cm and ID = 3.9 mm to test the ethylene bis(tetrabromophthalimide) prepared in this application.
[0037] Table 1: Performance Test Results Data Table
[0038] The performance test results show that the ethylene bis(tetrabromophthalimide) prepared in this application has high purity and yield, while the bromine content is maintained above 70%, keeping the product white.
[0039] A comparison of Comparative Examples 1-2 and Example 1 shows that Comparative Example 1, using the conventional method of first preparing tetrabromophthalic anhydride and then ethylene bis(tetrabromophthalimide), exhibits a significantly reduced bromine content, as indicated by performance testing. Furthermore, the prepared ethylene bis(tetrabromophthalimide) product has turned yellow, affecting its application in the flame retardant field. This application further demonstrates that, using water as a medium, it first synthesizes an ethylene bis(tetrabromophthalimide) intermediate via phthalic anhydride and ethylenediamine, and then prepares ethylene bis(tetrabromophthalimide) through a bromination reaction. This reduces the instantaneous and intense exothermic reaction caused by excessively high local bromine concentrations, decreases bromine volatilization, increases the bromine content and purity of the product, and maintains the product's white color.
[0040] In Comparative Example 2, conventional organic solvents were used as the medium to synthesize ethylene bis(phthalimide) intermediates from phthalic anhydride and ethylenediamine. Performance testing results showed that although a high bromine content was maintained in the product, the purity and yield of the prepared ethylene bis(tetrabromophthalimide) product were significantly reduced. This further illustrates that using water as the reaction medium instead of organic solvents can reduce pollution and improve product purity.
[0041] A comparison of Examples 9-11 and Example 1 shows that adding a chelating agent to the reaction solution before filtration significantly improves the purity and yield of the prepared product. This further demonstrates that the chelating agent can effectively remove metal ion impurities such as iron ions, reduce the oxidative degradation of the product by residual iron ions, reduce product decomposition and discoloration, and improve product purity.
[0042] 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 process for preparing a highly thermally stable ethylene bis(tetrabromophthalimide), characterized in that, The specific steps include: mixing phthalic anhydride and ethylenediamine in water, heating and reacting, centrifuging and drying to obtain an intermediate; mixing the intermediate with bromine, fuming sulfuric acid and a catalyst to obtain a reaction solution, heating and reacting, then removing acid, washing with water and drying to obtain ethylene bis(tetrabromophthalimide); the catalyst is a complex of ferric chloride and iodine; the removal of acid involves distilling the reaction solution, cooling and filtering to obtain the reaction product, washing with water and drying, and then aging to obtain ethylene bis(tetrabromophthalimide).
2. The preparation process of the highly thermally stable ethylene bis(tetrabromophthalimide) according to claim 1, characterized in that, The mass ratio of phthalic anhydride to ethylenediamine is 1:(3.5-5.5), and the mass ratio of the intermediate to bromine, fuming sulfuric acid, and catalyst is 1:(0.45-0.5):(0.1-0.2):(0.03-0.05).
3. The preparation process of the highly thermally stable ethylene bis(tetrabromophthalimide) according to claim 1, characterized in that, Mix in water and heat to a reaction temperature of 75-105℃.
4. The preparation process of the highly thermally stable ethylene bis(tetrabromophthalimide) according to claim 1, characterized in that, The intermediate is mixed with bromine, fuming sulfuric acid, and catalyst, and the reaction is heated to 130-150℃.
5. The preparation process of the highly thermally stable ethylene bis(tetrabromophthalimide) according to claim 1, characterized in that, The aging temperature is 250-280℃.
6. The preparation process of the highly thermally stable ethylene bis(tetrabromophthalimide) according to claim 3, characterized in that, Before filtration, a chelating agent is added to the reaction solution and mixed to react. The mass ratio of the chelating agent to the reaction solution is (0.01-0.02):
1.
7. The preparation process of the highly thermally stable ethylene bis(tetrabromophthalimide) according to claim 7, characterized in that, The chelating agent is one of aminotrimethylenephosphonic acid and ethylenediaminetetraacetic acid.