Preparation process of high-yield tetrachlorophthalic anhydride

Abstract

The application discloses a high-yield preparation process of tetrachlorophthalic anhydride, relates to the technical field of organic synthesis, and comprises the following steps: dissolving phthalic anhydride in chlorosulfonic acid, adding into a chlorination kettle, adding a catalyst, then performing temperature rising according to a certain procedure, starting to pass in chlorine when the temperature in the reaction kettle rises to 80-100 DEG C, adjusting and controlling the flow of chlorine, reacting while stirring, absorbing tail gas by using lye, and stopping the reaction when there is substantially no HCl gas escaping; filtering the material, recovering the catalyst solvent, and ensuring that the distillation temperature is not higher than 220 DEG C; after cooling, washing with cold water, centrifugal dehydration, and drying at 150-170 DEG C, tetrachlorophthalic anhydride is obtained; wherein the catalyst is a modified montmorillonite supported titanium tetrachloride catalyst. The preparation process of tetrachlorophthalic anhydride provided by the application has high yield and high purity, and is easy to be industrialized.

Description

Technical Field

[0001] This application relates to the field of organic synthesis technology, and in particular to a process for preparing tetrachlorophthalic anhydride in high yield. Background Technology

[0002] Tetrachlorophthalic anhydride, short for tetrachlorophthalic anhydride, is a colorless needle-like crystal or white powder. It is non-hygroscopic, sublimable, has a melting point of approximately 255-257℃, a boiling point of 371℃, is sparingly soluble in cold water, soluble in hot water (forming tetrachlorophthalic acid), readily soluble in tetrahydrofuran and dioxane, and soluble in solvents such as benzene, acetone, and chlorobenzene. Tetrachlorophthalic anhydride is widely used in flame retardants, pesticides, pigments, and coatings, especially as a reactive flame retardant for unsaturated polyesters and epoxy resins. It not only imparts good flame retardancy and mechanical properties to the resins but also provides good high-temperature resistance and light radiation stability. Furthermore, tetrachlorophthalic anhydride can be used to prepare a series of flame-retardant plasticizers with excellent comprehensive properties.

[0003] In the existing technology, the commonly used process routes for synthesizing tetrachlorophthalic anhydride are as follows: (1) Solvent method: one is the Pratt method, which uses fuming sulfuric acid as solvent and iodine as catalyst. The other is the liquid phase method, which uses chlorosulfonic acid as solvent and iodine trichloride as catalyst; (2) Melting method: phthalic anhydride is melted in a reactor, and chlorine gas is introduced at high temperature using molybdenum chloride as catalyst; (3) Gas phase method: phthalic anhydride is vaporized in the reaction, and the phthalic anhydride vapor is reacted through a fixed bed catalyst.

[0004] Although existing solvent-based methods for preparing tetrachlorophthalic anhydride are relatively mature, some problems still need to be addressed. For example, the solvent method results in many reaction byproducts due to harsh reaction conditions, and the yield is low. Therefore, a new method for preparing tetrachlorophthalic anhydride is needed to improve yield and economic efficiency. Summary of the Invention

[0005] To improve the yield of tetrachlorophthalic anhydride, this application provides a high-yield tetrachlorophthalic anhydride preparation process.

[0006] This application provides a high-yield preparation process for tetrachlorophthalic anhydride, employing the following technical solution: A process for preparing tetrachlorophthalic anhydride with high yield includes the following steps: Phthalic anhydride is dissolved in chlorosulfonic acid and added to a chlorination reactor. A catalyst is added, and the temperature is raised according to a specific procedure. When the temperature inside the reactor reaches 80-100℃, chlorine gas is introduced, and the flow rate of chlorine gas is adjusted and controlled. The reaction is carried out while stirring, and the reaction tail gas is absorbed with alkaline solution. The reaction is stopped when almost no HCl gas is released. The material is filtered, and the catalyst solvent is recovered. The distillation temperature should not exceed 220℃. After the residue is cooled, it is washed with cold water, centrifuged to remove water, and dried at 150-170℃ to obtain tetrachlorophthalic anhydride product. The catalyst is a modified montmorillonite-supported titanium tetrachloride catalyst.

[0007] By adopting the above technical solution, using chlorosulfonic acid as a solvent, phthalic anhydride reacts with chlorine gas at a certain temperature and under the action of a catalyst to obtain tetrachlorophthalic anhydride. The catalyst is a modified montmorillonite-supported titanium tetrachloride catalyst, with montmorillonite as an intercalator to support titanium tetrachloride in montmorillonite, resulting in a solid catalyst. This can improve the stability and reactivity of the catalyst, thereby achieving a highly efficient tetrachlorophthalic anhydride synthesis reaction, effectively improving the yield and purity of tetrachlorophthalic anhydride, and facilitating industrial production.

[0008] Preferably, the mass ratio of phthalic anhydride to chlorosulfonic acid is 1:(7-9).

[0009] By adopting the above technical solution and controlling the mass ratio of phthalic anhydride to solvent chlorosulfonic acid, the yield and purity of the reaction can be improved, avoiding the product crystallization and blockage of the chlorine pipeline due to insufficient solvent, or the reaction efficiency being reduced due to excessive solvent.

[0010] Preferably, the mass ratio of phthalic anhydride to catalyst is 1:(0.1-0.2).

[0011] By adopting the above technical solution and controlling the mass ratio of phthalic anhydride and catalyst, the reaction efficiency can be improved, unnecessary cost increases or side reactions can be avoided, and the reaction yield and purity can be effectively improved.

[0012] Preferably, the mass ratio of phthalic anhydride to chlorine is 1:(2-2.5).

[0013] Preferably, the flow rate of the chlorine gas is 4-5 kg / hour.

[0014] Preferably, the modified montmorillonite-supported titanium tetrachloride catalyst is made from the following raw materials in parts by weight: 3-6 parts magnesium dichloride, 80-100 parts solvent, 10-18 parts sodium montmorillonite, 165-205 parts hexane, 190-210 parts titanium tetrachloride, and 150-170 parts tetraethyl orthosilicate.

[0015] By adopting the above technical solution, titanium tetrachloride is an effective catalyst for the preparation of tetrachlorophthalic anhydride, with advantages such as high efficiency, stability, controllability and economy. However, titanium tetrachloride may be contaminated by impurities or react adversely with other substances during the reaction process, leading to catalyst deactivation and thus reducing reaction efficiency. Loading titanium tetrachloride into a composite material of magnesium dichloride and montmorillonite can not only significantly improve the reaction rate and selectivity and reduce the formation of reaction by-products, but also reduce catalyst loss, facilitate recovery, and allow for reuse, thereby reducing costs and minimizing the impact on equipment and the environment.

[0016] Preferably, the solvent is one of methanol, ethanol, butanol, and isopropanol.

[0017] Preferably, the preparation method of the modified montmorillonite-supported titanium tetrachloride catalyst includes the following steps: Under nitrogen protection, 3-6 parts of magnesium dichloride were added to 80-100 parts of solvent and stirred evenly at 55-65℃. Then, 10-18 parts of calcined sodium montmorillonite were added, and the mixture was stirred for 1-2 hours at 60-70℃. After filtration to remove excess solvent, solid product A was obtained. Solid product A was washed several times with 33-43 parts of hexane. 66-76 parts of hexane, 17-27 parts of titanium tetrachloride, and 150-170 parts of tetraethyl orthosilicate were added to solid product A and stirred for 1-2 hours at 60-70℃. After filtration to remove liquid, solid product B was washed several times with 33-43 parts of hexane. Then, the remaining titanium tetrachloride was added to solid product B and stirred for 2-3 hours at 80-90℃. After filtration to remove excess titanium tetrachloride, solid product C was washed several times with hexane and dried under reduced pressure to obtain the modified montmorillonite-supported titanium tetrachloride catalyst.

[0018] In summary, this application includes at least one of the following beneficial technical effects: 1. By adopting the above technical solution, using chlorosulfonic acid as a solvent, phthalic anhydride reacts with chlorine gas at a certain temperature and under the action of a catalyst to obtain tetrachlorophthalic anhydride. The catalyst is a modified montmorillonite-supported titanium tetrachloride catalyst. Montmorillonite is used as an intercalation layer to support titanium tetrachloride in montmorillonite to obtain a solid catalyst, which can improve the stability and reactivity of the catalyst, thereby realizing a highly efficient tetrachlorophthalic anhydride synthesis reaction and effectively improving the yield and purity of tetrachlorophthalic anhydride. 2. By adopting the above technical solution, titanium tetrachloride is an effective catalyst for the preparation of tetrachlorophthalic anhydride, with advantages such as high efficiency, stability, controllability, and economy. However, titanium tetrachloride may be contaminated by impurities or react adversely with other substances during the reaction process, leading to catalyst deactivation and thus reducing reaction efficiency. Loading titanium tetrachloride into a composite material of magnesium dichloride and montmorillonite can not only significantly improve the reaction rate and selectivity and reduce the formation of reaction by-products, but also reduce catalyst loss, facilitate recovery, allow for reuse, reduce costs, and minimize the impact on equipment and the environment. Detailed Implementation

[0019] The present application will be further described in detail below with reference to the embodiments.

[0020] Preparation Example Preparation Example 1 Under nitrogen protection, 3g of magnesium dichloride was added to 80g of methanol solvent and stirred at 55℃ and 300rpm for 2 hours. Then, 10g of sodium montmorillonite calcined at 400℃ was added, and the mixture was stirred at 60℃ for another hour. After filtration to remove excess methanol solvent, solid product A was obtained. Solid product A was washed several times with 33g of hexane. Then, 66g of hexane, 17g of titanium tetrachloride, and 150g of tetraethyl orthosilicate were added to solid product A, and the mixture was stirred at 60℃ for 1 hour. After filtration to remove the liquid, solid product B was obtained. Solid product B was washed several times with 33g of hexane. Then, the remaining 173g of titanium tetrachloride was added to solid product B, and the mixture was stirred at 80℃ for 2 hours. After filtration to remove excess titanium tetrachloride, solid product C was obtained. Solid product C was washed several times with 33g of hexane and dried under reduced pressure to obtain the modified montmorillonite-supported titanium tetrachloride catalyst.

[0021] Preparation Example 2 Under nitrogen protection, 4.5 g of magnesium dichloride was added to 90 g of isopropanol solvent and stirred at 60 °C and 350 rpm for 2.5 hours. Then, 14 g of sodium montmorillonite calcined at 450 °C was added, and the mixture was stirred at 65 °C for another 1.5 hours. After filtering to remove excess isopropanol solvent, solid product A was obtained. Solid product A was washed several times with 38 g of hexane. Then, 71 g of hexane, 22 g of titanium tetrachloride, and 160 g of tetraethyl orthosilicate were added to solid product A, and the mixture was stirred at 65 °C for 1.5 hours. After filtering to remove the liquid, solid product B was obtained. Solid product B was washed several times with 38 g of hexane. Then, the remaining 178 g of titanium tetrachloride was added to solid product B, and the mixture was stirred at 85 °C for 2.5 hours. After filtering to remove excess titanium tetrachloride, solid product C was obtained. Solid product C was washed several times with 38 g of hexane and dried under reduced pressure to obtain the modified montmorillonite-supported titanium tetrachloride catalyst.

[0022] Preparation Example 3 Under nitrogen protection, 6g of magnesium dichloride was added to 100g of butanol solvent and stirred at 65℃ and 400rpm for 3 hours. Then, 18g of sodium montmorillonite calcined at 500℃ was added, and the mixture was stirred at 70℃ for another 2 hours. After filtering to remove excess butanol solvent, solid product A was obtained. Solid product A was washed several times with 43g of hexane. Then, 76g of hexane, 27g of titanium tetrachloride, and 170g of tetraethyl orthosilicate were added to solid product A, and the mixture was stirred at 70℃ for 2 hours. After filtering to remove the liquid, solid product B was obtained. Solid product B was washed several times with 43g of hexane. Then, the remaining 183g of titanium tetrachloride was added to solid product B, and the mixture was stirred at 90℃ for 3 hours. After filtering to remove excess titanium tetrachloride, solid product C was obtained. Solid product C was washed several times with 43g of hexane and dried under reduced pressure to obtain the modified montmorillonite-supported titanium tetrachloride catalyst. Example

[0023] Example 1 50g of phthalic anhydride was dissolved in 350g of chlorosulfonic acid and added to a chlorination reactor. 5g of the catalyst modified montmorillonite supported on titanium tetrachloride obtained in Preparation Example 1 was added and stirred until homogeneous. The temperature was then increased according to a specific program. When the temperature inside the reactor reached 80°C, chlorine gas was introduced. The flow rate of chlorine gas was adjusted and controlled at 4 kg / hour, and the total amount of chlorine gas introduced was 100g. The reaction was carried out while stirring, and the reaction tail gas was absorbed with alkaline solution. The reaction was stopped when almost no HCl gas was released. The product was filtered, the catalyst was recovered, and the product was distilled to recover the solvent at a distillation temperature of 120°C. After cooling, the residue was washed with cold water, centrifuged to remove water, and dried at 150°C for 2 hours to obtain tetrachlorophthalic anhydride product.

[0024] Example 2 50g of phthalic anhydride was dissolved in 350g of chlorosulfonic acid and added to a chlorination reactor. 5g of the catalyst modified montmorillonite supported on titanium tetrachloride obtained in Preparation Example 1 was added and stirred until homogeneous. The temperature was then increased according to a specific program. When the temperature inside the reactor reached 90°C, chlorine gas was introduced. The flow rate of chlorine gas was adjusted and controlled at 4 kg / hour, and the total amount of chlorine gas introduced was 100g. The reaction was carried out while stirring, and the reaction tail gas was absorbed with alkaline solution. The reaction was stopped when almost no HCl gas was released. The product was filtered, the catalyst was recovered, and the product was distilled to recover the solvent at a distillation temperature of 140°C. After cooling, the residue was washed with cold water, centrifuged to remove water, and dried at 160°C for 3 hours to obtain tetrachlorophthalic anhydride product.

[0025] Example 3 50g of phthalic anhydride was dissolved in 350g of chlorosulfonic acid and added to a chlorination reactor. 5g of the catalyst modified montmorillonite supported on titanium tetrachloride obtained in Preparation Example 1 was added and stirred until homogeneous. The temperature was then increased according to a specific program. When the temperature inside the reactor reached 100°C, chlorine gas was introduced, and the flow rate of chlorine gas was adjusted and controlled at 4 kg / hour. The total amount of chlorine gas introduced was 100g. The reaction was carried out while stirring, and the reaction tail gas was absorbed with alkaline solution. The reaction was stopped when almost no HCl gas was released. The product was filtered, the catalyst was recovered, and the product was distilled to recover the solvent at a distillation temperature of 160°C. After cooling, the residue was washed with cold water, centrifuged to remove water, and dried at 170°C for 4 hours to obtain tetrachlorophthalic anhydride product.

[0026] Example 4 The difference between Example 4 and Example 1 is that the mass of chlorosulfonic acid used in Example 4 is 400g.

[0027] Example 5 The difference between Example 5 and Example 1 is that the mass of chlorosulfonic acid used in Example 5 is 450g.

[0028] Example 6 The difference between Example 6 and Example 1 is that the mass of chlorosulfonic acid used in Example 6 is 300g.

[0029] Example 7 The difference between Example 7 and Example 1 is that the mass of chlorosulfonic acid used in Example 7 is 500g.

[0030] Example 8 The difference between Example 8 and Example 1 is that the catalyst modified montmorillonite supported titanium tetrachloride catalyst used in Example 8 was derived from Preparation Example 1, with a mass of 7.5g.

[0031] Example 9 The difference between Example 9 and Example 1 is that the catalyst modified montmorillonite supported titanium tetrachloride catalyst used in Example 9 was derived from Preparation Example 1, with a mass of 10g.

[0032] Example 10 The difference between Example 10 and Example 1 is that the catalyst modified montmorillonite supported titanium tetrachloride catalyst used in Example 10 is from Preparation Example 1, with a mass of 3g.

[0033] Example 11 The difference between Example 11 and Example 1 is that the catalyst modified montmorillonite supported titanium tetrachloride catalyst used in Example 11 was derived from Preparation Example 1 and weighed 13g.

[0034] Example 12 The difference between Example 12 and Example 1 is that the catalyst modified montmorillonite supported titanium tetrachloride catalyst used in Example 12 was derived from Preparation Example 2, with a mass of 5g.

[0035] Example 13 The difference between Example 13 and Example 1 is that the catalyst modified montmorillonite supported titanium tetrachloride catalyst used in Example 13 was derived from Preparation Example 3, with a mass of 5g.

[0036] Example 14 The difference between Example 14 and Example 1 is that the total mass of chlorine gas used in Example 14 is 112.5g.

[0037] Example 15 The difference between Example 15 and Example 1 is that the total mass of chlorine gas used in Example 15 is 125g.

[0038] Example 16 The difference between Example 16 and Example 1 is that the total mass of chlorine gas used in Example 16 is 87g.

[0039] Example 17 The difference between Example 17 and Example 1 is that the total mass of chlorine gas used in Example 17 is 138g.

[0040] Example 18 The difference between Example 18 and Example 1 is that the chlorine flow rate used in Example 18 is 4.5 kg / hour.

[0041] Example 19 The difference between Example 19 and Example 1 is that the chlorine flow rate used in Example 19 is 5 kg / hour.

[0042] Example 20 The difference between Example 20 and Example 1 is that the chlorine flow rate used in Example 20 is 3 kg / hour.

[0043] Example 21 The difference between Example 21 and Example 1 is that the chlorine flow rate used in Example 21 is 6 kg / hour.

[0044] Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the catalyst used in Comparative Example 1 is unmodified liquid titanium tetrachloride, with a mass of 5g.

[0045] Performance testing 1. The mass of tetrachlorophthalic anhydride obtained in Examples 1-21 and Comparative Example 1 was measured and its yield was calculated. The results are shown in Table 1.

[0046] 2. The purity of the triphenylphosphine products obtained in Examples 1-21 and Comparative Example 1 was determined by gas chromatography, and the results are shown in Table 1.

[0047] The specific test results are as follows: Table 1 Performance Test Results As can be seen from the test results of Examples 1-3, the tetrachlorophthalic anhydride preparation process provided in this application has a high yield and purity, wherein the yield of tetrachlorophthalic anhydride can reach more than 94% and the purity can reach more than 98%.

[0048] The test results of Examples 1, 4, 5, 6, and 7 show that when the mass ratio of phthalic anhydride to chlorosulfonic acid used in the preparation of tetrachlorophthalic anhydride in this application is 1:(7-9), it is beneficial to obtain a higher yield and higher purity of tetrachlorophthalic anhydride. However, when the mass ratio of phthalic anhydride to chlorosulfonic acid is lower or higher than this range, the yield and purity of the obtained tetrachlorophthalic anhydride decrease significantly.

[0049] The test results of Examples 1, 8, 9, 10, and 11 show that when the mass ratio of phthalic anhydride to the catalyst-modified montmorillonite-supported titanium tetrachloride catalyst used in the preparation of tetrachlorophthalic anhydride in this application is 1:(0.1-0.2), it is beneficial to obtain a higher yield and higher purity of tetrachlorophthalic anhydride. However, when the mass ratio of phthalic anhydride to the catalyst-modified montmorillonite-supported titanium tetrachloride catalyst is lower or higher than this range, the yield and purity of the obtained tetrachlorophthalic anhydride decrease significantly.

[0050] The test results of Examples 1, 12, 13 and Comparative Example 1 show that the components and preparation method of the catalyst-modified montmorillonite-supported titanium tetrachloride catalyst provided in this application are all beneficial for obtaining catalysts with high catalytic activity, and can effectively improve the yield and purity of tetrachlorophthalic anhydride, as can be seen from the test results of Preparation Example 1. However, when using unmodified liquid titanium tetrachloride as a catalyst, the yield and purity of the obtained tetrachlorophthalic anhydride are significantly lower.

[0051] The test results of Examples 1, 14, 15, 16, and 17 show that when the mass ratio of phthalic anhydride to chlorine used in the preparation of tetrachlorophthalic anhydride in this application is 1:(2-2.5), it is beneficial to obtain a higher yield and higher purity of tetrachlorophthalic anhydride. However, when the mass ratio of phthalic anhydride to chlorine is lower or higher than this range, the yield and purity of the obtained tetrachlorophthalic anhydride decrease significantly.

[0052] The test results of Examples 1, 18, 19, 20, and 21 show that when the flow rate of chlorine gas used in the preparation of tetrachlorophthalic anhydride in this application is 4-5 kg / hour, it is beneficial to obtain a higher yield and higher purity of tetrachlorophthalic anhydride; however, when the flow rate of chlorine gas is lower or higher than this range, the yield and purity of the obtained tetrachlorophthalic anhydride decrease significantly.

[0053] 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 tetrachlorophthalic anhydride with high yield, characterized in that: Includes the following steps: Phthalic anhydride is dissolved in chlorosulfonic acid and added to a chlorination reactor. A catalyst is added, and the temperature is raised according to a specific procedure. When the temperature inside the reactor reaches 80-100℃, chlorine gas is introduced, and the flow rate of chlorine gas is adjusted and controlled. The reaction is carried out while stirring, and the reaction tail gas is absorbed with alkaline solution. The reaction is stopped when almost no HCl gas is released. The material is filtered, and the catalyst solvent is recovered. The distillation temperature must not exceed 220℃. After the residue is cooled, it is washed with cold water, centrifuged to remove water, and dried at 150-170℃ to obtain tetrachlorophthalic anhydride product. The catalyst is a modified montmorillonite-supported titanium tetrachloride catalyst, which is prepared from the following raw materials in parts by weight: 3-6 parts magnesium dichloride, 80-100 parts solvent, 10-18 parts sodium montmorillonite, 165-205 parts hexane, 190-210 parts titanium tetrachloride, and 150-170 parts tetraethyl orthosilicate. The preparation method of the modified montmorillonite-supported titanium tetrachloride catalyst includes the following steps: Under nitrogen protection, 3-6 parts of magnesium dichloride were added to 80-100 parts of solvent and stirred evenly at 55-65℃. 10-18 parts of calcined sodium montmorillonite were added, and stirring was continued at 60-70℃ for 1-2 hours. After filtration to remove excess solvent, solid product A was obtained. Solid product A was washed several times with 33-43 parts of hexane. 66-76 parts of hexane, 17-27 parts of titanium tetrachloride, and 150-170 parts of tetraethyl orthosilicate were added to solid product A and stirred at 60-70℃ for 1-2 hours. After filtration to remove liquid, solid product B was washed several times with 33-43 parts of hexane. Then, the remaining titanium tetrachloride was added to solid product B and stirred at 80-90℃ for 2-3 hours. After filtration to remove excess titanium tetrachloride, solid product C was washed several times with hexane and dried under reduced pressure to obtain the modified montmorillonite-supported titanium tetrachloride catalyst. The mass ratio of phthalic anhydride to chlorosulfonic acid is 1:(7-9).

2. The preparation process of high-yield tetrachlorophthalic anhydride according to claim 1, characterized in that: The mass ratio of phthalic anhydride to catalyst is 1:(0.1-0.2).

3. The preparation process of high-yield tetrachlorophthalic anhydride according to claim 1, characterized in that: The mass ratio of phthalic anhydride to chlorine is 1:(2-2.5).

4. The preparation process of high-yield tetrachlorophthalic anhydride according to claim 1, characterized in that: The flow rate of the chlorine gas is 4-5 kg / hour.

5. The preparation process of high-yield tetrachlorophthalic anhydride according to claim 1, characterized in that: The solvent is one of methanol, ethanol, butanol, and isopropanol.

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