Preparation process of high-purity tetrachlorophthalic anhydride
Through the oxidation system of potassium permanganate and ascorbic acid combined with the catalysis of copper chloride and 18-crown ether-6, the problem of insufficient oxidation in synthesis of tetrachlorophenol is solved, and the preparation of high-purity tetrachlorophenol is achieved, and the product quality is improved .
Patent Information
- Application Number
- CN202411299698.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-18
- Publication Date
- 2024-12-20
AI Technical Summary
In the existing tetrachlorophenol synthesis process, the product purity is insufficient due to insufficient oxidation, and the existence of by-products affects the quality of the final product.
The oxidation treatment of tetrachlorophenol is carried out using a mixed system of potassium permanganate and ascorbic acid. The hydroxyl group or other functional groups are introduced through the strong oxidation of potassium permanganate, and the oxidation reaction is controlled through ascorbic acid to prevent excessive oxidation. At the same time, copper chloride and 18-Crown ether-6 acts as a catalyst and stabilizer to optimize the reaction path and reaction conditions.
The oxidation effect and purity of tetrachlorophenol is significantly improved, the occurrence of side reactions is reduced, and high-purity tetrachlorophenol crystals are obtained.
Abstract
Description
Technical Field
[0001] The present application relates to the field of a high-purity tetrachlorophthalic anhydride preparation process, and to the field of tetrachlorophthalic anhydride preparation. Background Art
[0002] At present, the traditional method for synthesizing tetrachlorophenol involves the chlorination process of phenol, in which a chlorinating agent reacts with phenol to produce tetrachlorophenol. However, this process is often accompanied by the generation of by-products, resulting in insufficient product purity.
[0003] The main reason for insufficient purity is the problem of insufficient oxidation in the tetrachlorophenol refining process. Insufficient oxidation will lead to the failure of complete conversion of byproducts generated in the chlorination process, and the presence of these byproducts will affect the purity and quality of the final product. In view of the above-mentioned related technologies, the inventors believe that the existing tetrachlorophthalic anhydride production process has reduced product purity due to insufficient oxidation of tetrachlorophenol. Summary of the invention
[0004] In order to improve the problem of insufficient oxidation in the production process of tetrachlorophenol, the present application provides a high-purity tetrachlorophthalic anhydride preparation process The present application provides a high-purity tetrachlorophthalic anhydride preparation process, which adopts the following technical scheme: A high-purity tetrachlorophthalic anhydride preparation process comprises the following steps: Potassium permanganate and ascorbic acid are mixed to prepare a solution, and crude tetrachlorophenol is added to the potassium permanganate-ascorbic acid mixed system to react to obtain an oxidized reaction mixture; The oxidized reaction mixture is extracted, washed and dried to obtain tetrachlorophenol crystals.
[0005] By adopting the above technical solution, adding potassium permanganate to tetrachlorophenol can further oxidize tetrachlorophenol to introduce hydroxyl groups or other functional groups, or improve the oxidation effect of tetrachlorophenol by changing the oxidation state of existing substituents. At the same time, since potassium permanganate is a strong oxidant, the progress of the oxidation reaction is controlled by adding ascorbic acid to prevent excessive oxidation.
[0006] Preferably, the mass ratio of potassium permanganate, ascorbic acid and crude tetrachlorophenol is 1-2:0.5-1:3.
[0007] By adopting the above technical solution, insufficient addition of potassium permanganate will lead to incomplete oxidation, and excessive addition will lead to over-oxidation, which will affect the reactants. Adding ascorbic acid can control the progress of the oxidation reaction and prevent over-oxidation.
[0008] Preferably, the preparation process of crude tetrachlorophenol comprises the following steps: The p-chlorophenol solution is prepared by dissolving p-chlorophenol in dichloromethane; the catalyst is continuously added to the p-chlorophenol solution, and excessive chlorine gas is continuously introduced; after the reaction is completed, the solution is cooled to room temperature, and the solid reactant is filtered out to obtain crude tetrachlorophenol; the chlorine introduction rate is 0.2-0.5 L / h, the reaction temperature is 50-60°C, and the reaction time is 3.5-4h.
[0009] Preferably, the catalyst is ferric chloride.
[0010] By adopting the above technical solution, the lone pair of electrons of p-chlorophenol is accepted to form a complex, thereby activating the hydrogen atoms on the phenol, making it easier to be replaced by chlorine, accelerating the reaction rate of converting p-chlorophenol to tetrachlorophenol, and improving the oxidation effect.
[0011] Preferably, the mass ratio of p-chlorophenol to catalyst is 10:3-5.
[0012] Preferably, the preparation process of para-chlorophenol comprises the following steps: After mixing phenol, a catalyst, a stabilizer and a solvent hydrochloric acid, filtered chlorine is continuously introduced under a reaction condition of 90° C. to obtain para-chlorophenol; the introduction rate of chlorine is 0.4-0.6 L / h, and the reaction time is 2.5-3 h; the mass ratio of phenol, catalyst and stabilizer is 20:5-8:0.5-0.8.
[0013] Preferably, the catalyst is cupric chloride; and the stabilizer is 18-crown ether-6.
[0014] By adopting the above technical solution, copper chloride as a catalyst can reduce the activation energy of the reaction, control the reaction path, and make the chlorine atom more inclined to replace the para position of the phenol molecule to generate para-chlorophenol instead of other isomers. 18-Crown ether-6 as a stabilizer can form a complex with copper chloride to prevent the catalyst from decomposing or polymerizing during the reaction, thereby reducing the occurrence of side reactions and further improving the oxidation efficiency.
[0015] Preferably, the extraction comprises the steps of: The oxidized reaction mixture was cooled to room temperature, 100-200 mL of dichloromethane was added for extraction, and the organic phase was separated.
[0016] Preferably, washing comprises the steps of: The organic phase was washed with 50-100 mL of 2% sulfuric acid solution and 50 mL of distilled water in sequence.
[0017] Preferably, drying comprises the steps of: The washed organic phase and anhydrous magnesium chloride are placed in a drying oven at room temperature and dried for 10-12 hours; then freeze-dried to obtain tetrachlorophenol crystals.
[0018] In summary, the present application includes at least one of the following beneficial technical effects: 1. Adding potassium permanganate to tetrachlorophenol can further oxidize tetrachlorophenol to introduce hydroxyl groups or other functional groups, or improve the oxidation effect of tetrachlorophenol by changing the oxidation state of existing substituents. At the same time, since potassium permanganate is a strong oxidant, the process of oxidation reaction can be controlled by adding ascorbic acid to prevent over-oxidation.
[0019] 2. By accepting the lone pair of electrons of p-chlorophenol to form a complex, the hydrogen atoms on phenol are activated, making it easier to be replaced by chlorine, accelerating the reaction rate of p-chlorophenol to tetrachlorophenol, and improving the oxidation effect.
[0020] 3. As a catalyst, copper chloride can reduce the activation energy of the reaction and control the reaction path, making the chlorine atom more inclined to replace the para position of the phenol molecule to generate para-chlorophenol rather than other isomers. As a stabilizer, 18-crown-6 can form a complex with copper chloride to prevent the catalyst from decomposing or polymerizing during the reaction, thereby reducing the occurrence of side reactions and further improving the oxidation efficiency. DETAILED DESCRIPTION
[0021] The present application is further described in detail below with reference to the embodiments. Example
[0022] Example 1 S1. Add 20 g of phenol, 6 g of copper chloride, 0.6 g of 18-crown ether-6 and 50 mL of hydrochloric acid into a four-necked flask; introduce nitrogen gas into the four-necked flask to exclude oxygen.
[0023] S2. Heat the mixture in step S1 to 90° C., and introduce chlorine gas into the four-necked flask at a rate of 0.4-0.6 L / h; continue the reaction for 2.5-3 h to obtain p-chlorophenol.
[0024] S3. Dissolve 10 g of p-chlorophenol in 30 mL of dichloromethane to form a p-chlorophenol solution; continue to add 4 g of ferric chloride to the p-chlorophenol solution. Pass chlorine gas into the p-chlorophenol-ferric chloride mixture system; the chlorine gas passing rate is 0.2-0.5 L / h, the reaction temperature is 50-60°C, and the reaction time is 3.5-4h.
[0025] S4. After the reaction is completed, the product is cooled to room temperature, filtered to remove the solid catalyst, and crude tetrachlorophenol is obtained.
[0026] S5. Weigh 1.5 g potassium permanganate and 0.8 g ascorbic acid and dissolve them in 30 mL distilled water; continue to add 3 g crude tetrachlorophenol to the potassium permanganate-ascorbic acid mixture. Control the reaction temperature to 40-50° C. and the reaction time to 1.5-2 h to obtain an oxidized reaction mixture.
[0027] S6. The oxidized reaction mixture was cooled to room temperature, 100-200 mL of dichloromethane was added for extraction, and the organic phase was separated.
[0028] S7. Wash the organic phase with 50-100 mL of 2% sulfuric acid solution to remove residual inorganic matter, and then wash again with 50 mL of distilled water to remove acidic substances.
[0029] S8. Place the washed organic phase and anhydrous magnesium chloride in a drying oven at room temperature and dry for 10-12 hours; then place the dried organic phase in a freeze dryer and set the temperature to minus 20°C. After freeze drying, high-purity tetrachlorophenol crystals are obtained.
[0030] Example 2 S1. Add 20 g of phenol, 6 g of copper chloride, 0.6 g of 18-crown ether-6 and 50 mL of hydrochloric acid into a four-necked flask; introduce nitrogen gas into the four-necked flask to exclude oxygen.
[0031] S2. Heat the mixture in step S1 to 90° C., and introduce chlorine gas into the four-necked flask at a rate of 0.4-0.6 L / h; continue the reaction for 2.5-3 h to obtain p-chlorophenol.
[0032] S3. Dissolve 10 g of p-chlorophenol in 30 mL of dichloromethane to form a p-chlorophenol solution; continue to add 4 g of ferric chloride to the p-chlorophenol solution. Pass chlorine gas into the p-chlorophenol-ferric chloride mixture system; the chlorine gas passing rate is 0.2-0.5 L / h, the reaction temperature is 50-60°C, and the reaction time is 3.5-4h.
[0033] S4. After the reaction is completed, the product is cooled to room temperature, filtered to remove the solid catalyst, and crude tetrachlorophenol is obtained.
[0034] S5. Weigh 1.5 g potassium permanganate and 0.8 g ascorbic acid and dissolve them in 30 mL distilled water; continue to add 3 g crude tetrachlorophenol to the potassium permanganate-ascorbic acid mixture. Control the reaction temperature to 40-50° C. and the reaction time to 1.5-2 h to obtain an oxidized reaction mixture.
[0035] S6. The oxidized reaction mixture was cooled to room temperature, 100-200 mL of dichloromethane was added for extraction, and the organic phase was separated.
[0036] S7. Wash the organic phase with 50-100 mL of 2% sulfuric acid solution to remove residual inorganic matter, and then wash again with 50 mL of distilled water to remove acidic substances.
[0037] S8. Place the washed organic phase and anhydrous magnesium chloride in a drying oven at room temperature and dry for 10-12 hours; then place the dried organic phase in a freeze dryer and set the temperature to minus 20°C. After freeze drying, high-purity tetrachlorophenol crystals are obtained.
[0038] Example 3 S1. Add 20 g of phenol, 6 g of copper chloride, 0.6 g of 18-crown ether-6 and 50 mL of hydrochloric acid into a four-necked flask; introduce nitrogen gas into the four-necked flask to exclude oxygen.
[0039] S2. Heat the mixture in step S1 to 90° C., and introduce chlorine gas into the four-necked flask at a rate of 0.4-0.6 L / h; continue the reaction for 2.5-3 h to obtain p-chlorophenol.
[0040] S3. Dissolve 10 g of p-chlorophenol in 30 mL of dichloromethane to form a p-chlorophenol solution; continue to add 4 g of ferric chloride to the p-chlorophenol solution. Pass chlorine gas into the p-chlorophenol-ferric chloride mixture system; the chlorine gas passing rate is 0.2-0.5 L / h, the reaction temperature is 50-60°C, and the reaction time is 3.5-4h.
[0041] S4. After the reaction is completed, the product is cooled to room temperature, filtered to remove the solid catalyst, and crude tetrachlorophenol is obtained.
[0042] S5. Weigh 1.5 g potassium permanganate and 0.8 g ascorbic acid and dissolve them in 30 mL distilled water; continue to add 3 g crude tetrachlorophenol to the potassium permanganate-ascorbic acid mixture. Control the reaction temperature to 40-50° C. and the reaction time to 1.5-2 h to obtain an oxidized reaction mixture.
[0043] S6. The oxidized reaction mixture was cooled to room temperature, 100-200 mL of dichloromethane was added for extraction, and the organic phase was separated.
[0044] S7. Wash the organic phase with 50-100 mL of 2% sulfuric acid solution to remove residual inorganic matter, and then wash again with 50 mL of distilled water to remove acidic substances.
[0045] S8. Place the washed organic phase and anhydrous magnesium chloride in a drying oven at room temperature and dry for 10-12 hours; then place the dried organic phase in a freeze dryer and set the temperature to minus 20°C. After freeze drying, high-purity tetrachlorophenol crystals are obtained.
[0046] Example 4 The difference between Example 4 and Example 1 is that the amount of hydrochloric acid is 100 mL.
[0047] Example 5 The difference between Example 5 and Example 1 is that the amount of dichloromethane is 60 mL.
[0048] Example 6 The difference between Example 6 and Example 1 is that the amount of distilled water is 60 mL.
[0049] Example 7 The difference between Example 7 and Example 1 is that the amount of cupric chloride added is 5 g.
[0050] Example 8 The difference between Example 8 and Example 1 is that the amount of cupric chloride added is 8 g.
[0051] Example 9 The difference between Example 9 and Example 1 is that the amount of cupric chloride added is 3 g.
[0052] Example 10 The difference between Example 10 and Example 1 is that the amount of cupric chloride added is 10 g.
[0053] Embodiment 11 The difference between Example 11 and Example 1 is that cupric chloride is replaced by an equal mass of ferric chloride.
[0054] Example 12 The difference between Example 12 and Example 1 is that the added amount of 18-crown ether-6 is 0.5 g.
[0055] Example 13 The difference between Example 13 and Example 1 is that the added amount of 18-crown ether-6 is 0.8 g.
[0056] Embodiment 14 The difference between Example 14 and Example 1 is that the added amount of 18-crown ether-6 is 0.2 g.
[0057] Embodiment 15 The difference between Example 15 and Example 1 is that the added amount of 18-crown ether-6 is 1.0 g.
[0058] Example 16 The difference between Example 16 and Example 1 is that 18-crown ether-6 is replaced by an equal mass of 15-crown ether-5.
[0059] Embodiment 17 The difference between Example 17 and Example 1 is that 18-crown ether-6 is replaced by an equal mass of tetramethylammonium chloride.
[0060] Embodiment 18 The difference between Example 18 and Example 1 is that the amount of ferric chloride added is 3 g.
[0061] Embodiment 19 The difference between Example 29 and Example 1 is that the amount of ferric chloride added is 5 g.
[0062] Embodiment 20 The difference between Example 20 and Example 1 is that the amount of ferric chloride added is 2 g.
[0063] Embodiment 21 The difference between Example 21 and Example 1 is that the amount of ferric chloride added is 8 g.
[0064] Embodiment 22 The difference between Example 22 and Example 1 is that ferric chloride is replaced by an equal mass of cupric chloride.
[0065] Embodiment 23 The difference between Example 23 and Example 1 is that ferric chloride is replaced by an equal mass of ferrous sulfate.
[0066] Embodiment 24 The difference between Example 24 and Example 1 is that the amount of potassium permanganate added is 1 g.
[0067] Embodiment 25 The difference between Example 25 and Example 1 is that the amount of potassium permanganate added is 2 g.
[0068] Embodiment 26 The difference between Example 29 and Example 1 is that the amount of ascorbic acid added is 0.5 g.
[0069] Embodiment 27 The difference between Example 30 and Example 1 is that the amount of ascorbic acid added is 1 g.
[0070] Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the added amount of potassium permanganate is 0.5 g.
[0071] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the amount of potassium permanganate added is 3 g.
[0072] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that potassium permanganate is replaced by manganese dioxide.
[0073] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that potassium permanganate is replaced by hydrogen peroxide.
[0074] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that the amount of ascorbic acid added is 0.2 g.
[0075] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that the amount of ascorbic acid added is 2 g.
[0076] Comparative Example 7 The difference between Comparative Example 7 and Example 1 is that ascorbic acid is replaced by lipoic acid.
[0077] Comparative Example 8 The difference between Comparative Example 8 and Example 1 is that ascorbic acid is replaced by sodium ascorbate.
[0078] Performance testing The purity of tetrachlorophenol crystals in Examples 1-27 and Comparative Examples 1-8 was measured respectively with reference to the standard HJ 744-2015 Determination of Phenolic Compounds in Water Quality. The specific test results are shown in Table 1.
[0079] Table 1 Purity of tetrachlorophenol crystals prepared in Examples 1-27 and Comparative Examples 1-8 purity / % purity / % Example 1 98.5 Embodiment 19 98.8 Example 2 98.3 Embodiment 20 96.3 Example 3 98.6 Embodiment 21 97.0 Example 4 98.1 Embodiment 22 78.6 Example 5 98.4 Embodiment 23 83.3 Example 6 98.3 Embodiment 24 98.4 Example 7 98.1 Embodiment 25 98.7 Example 8 98.8 Embodiment 26 97.9 Example 9 96.2 Embodiment 27 99.0 Example 10 96.6 Comparative Example 1 94.1 Embodiment 11 84.1 Comparative Example 2 95.2 Example 12 98.2 Comparative Example 3 85.2 Example 13 98.7 Comparative Example 4 80.5 Embodiment 14 96.6 Comparative Example 5 92.1 Embodiment 15 96.9 Comparative Example 6 94.9 Example 16 90.3 Comparative Example 7 78.3 Embodiment 17 80.2 Comparative Example 8 76.2 Embodiment 18 98.3 It can be seen from Examples 1-6 that when hydrochloric acid, dichloromethane and distilled water are used as solvents, the sample concentration in the system will change when the solvent changes, and the change in sample concentration has little effect on the purity of tetrachlorophenol.
[0080] It can be seen from Example 1 and Examples 7-11 that when the amount of cupric chloride added is 5-8 g, the purity of the tetrachlorophenol crystals gradually increases with the increase in the amount of cupric chloride added; when the amount of cupric chloride added is outside the range of 5-8 g, the purity of the tetrachlorophenol crystals decreases; when cupric chloride is replaced by ferric chloride, the purity of the tetrachlorophenol crystals significantly decreases.
[0081] It can be seen from Example 1 and Examples 12-17 that when the amount of 18-crown ether-6 added is 0.5-0.8 g, the purity of the tetrachlorophenol crystals gradually increases with the increase in the amount of 18-crown ether-6 added; when the amount of 18-crown ether-6 added is outside the range of 0.5-0.8 g, the purity of the tetrachlorophenol crystals decreases; after using 15-crown ether-5 and tetramethylammonium chloride instead of 18-crown ether-6, the purity of the tetrachlorophenol crystals is significantly reduced.
[0082] It can be seen from Example 1 and Examples 18-23 that when the amount of ferric chloride added is 3-5 g, the purity of the tetrachlorophenol crystals gradually increases with the increase in the amount of ferric chloride added; when the amount of ferric chloride added is outside the range of 3-5 g, the purity of the tetrachlorophenol crystals decreases; after using cupric chloride and ferrous sulfate instead of 18-crown ether-6, the purity of the tetrachlorophenol crystals is significantly reduced.
[0083] It can be seen from Example 1, Examples 24-25, and Comparative Examples 1-4 that when the amount of potassium permanganate added is 1-2 g, the purity of the tetrachlorophenol crystals gradually increases with the increase in the amount of potassium permanganate added; when the amount of potassium permanganate added is outside the range of 1-2 g, the purity of the tetrachlorophenol crystals decreases; after manganese dioxide and hydrogen peroxide are used instead of potassium permanganate, the purity of the tetrachlorophenol crystals is significantly reduced.
[0084] It can be seen from Example 1, Examples 26-27, and Comparative Examples 5-8 that when the amount of ascorbic acid added is 0.5-1g, the purity of the tetrachlorophenol crystals gradually increases with the increase in the amount of ascorbic acid added; when the amount of ascorbic acid added is outside the range of 0.5-1g, the purity of the tetrachlorophenol crystals decreases; after using thioctic acid and sodium ascorbate instead of ascorbic acid, the purity of the tetrachlorophenol crystals is significantly reduced.
[0085] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.
Claims
1. A process for preparing high-purity tetrachlorophthalic anhydride, characterized in that: The steps include: Potassium permanganate and ascorbic acid are mixed to prepare a solution, and crude tetrachlorophenol is added to the potassium permanganate-ascorbic acid mixed system to react to obtain an oxidized reaction mixture; The oxidized reaction mixture is extracted, washed and dried to obtain tetrachlorophenol crystals.
2. A process for preparing high-purity tetrachlorophthalic anhydride according to claim 1, characterized in that: The mass ratio of potassium permanganate, ascorbic acid and crude tetrachlorophenol is 1-2:0.5-1:
3.
3. A process for preparing high-purity tetrachlorophthalic anhydride according to claim 1, characterized in that: The preparation process of crude tetrachlorophenol comprises the following steps: The p-chlorophenol solution is prepared by dissolving p-chlorophenol in dichloromethane; the catalyst is continuously added to the p-chlorophenol solution, and excessive chlorine gas is continuously introduced; after the reaction is completed, the solution is cooled to room temperature, and the solid reactant is filtered out to obtain crude tetrachlorophenol; the chlorine introduction rate is 0.2-0.5 L / h, the reaction temperature is 50-60°C, and the reaction time is 3.5-4h.
4. A process for preparing high-purity tetrachlorophthalic anhydride according to claim 3, characterized in that: The catalyst is ferric chloride.
5. A process for preparing high-purity tetrachlorophthalic anhydride according to claim 1 or 4, characterized in that: The mass ratio of p-chlorophenol to the catalyst is 10:3-5.
6. A process for preparing high-purity tetrachlorophthalic anhydride according to claim 3, characterized in that: The preparation process of para-chlorophenol comprises the following steps: After mixing phenol, a catalyst, a stabilizer and a solvent hydrochloric acid, filtered chlorine is continuously introduced under a reaction condition of 90° C. to obtain para-chlorophenol; the introduction rate of chlorine is 0.4-0.6 L / h, and the reaction time is 2.5-3 h; the mass ratio of phenol, catalyst and stabilizer is 20:5-8:0.5-0.
8.
7. A process for preparing high-purity tetrachlorophthalic anhydride according to claim 5, characterized in that: The catalyst is cupric chloride; the stabilizer is 18-crown ether-6.
8. A process for preparing high-purity tetrachlorophthalic anhydride according to claim 1, characterized in that: The extraction process includes the following steps: The oxidized reaction mixture was cooled to room temperature, 100-200 mL of dichloromethane was added for extraction, and the organic phase was separated.
9. A process for preparing high-purity tetrachlorophthalic anhydride according to claim 8, characterized in that washing comprises the following steps: The organic phase was washed with 50-100 mL of 2% sulfuric acid solution and 50 mL of distilled water in sequence.
10. A process for preparing high-purity tetrachlorophthalic anhydride according to claim 9, characterized in that the drying comprises the following steps: The washed organic phase and anhydrous magnesium chloride are placed in a drying oven at room temperature and dried for 10-12 hours; then freeze-dried to obtain tetrachlorophenol crystals.