Process for the synthesis of 1,4-bis[4',6'-bis(4-n-propylphenoxy)-1',3',5'-triazin-2'-oxy]benzene
By converting hydroquinone into disodium salt slurry and using a phase transfer catalyst and a green carbonate solvent, the problems of cumbersome compound synthesis steps and complex post-processing in the prior art have been solved, and the industrial production of 1,4-bis[4',6'-bis(4-n-propylphenoxy)-1',3',5'-triazine-2'-oxy]benzene with high yield and high purity has been realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GCH TECH
- Filing Date
- 2026-02-27
- Publication Date
- 2026-06-02
AI Technical Summary
Existing technologies for preparing complex functional compounds suffer from problems such as multiple reaction steps, large amounts of highly polar or high-boiling-point solvents, high inorganic salt loading, high system viscosity, and difficult post-processing, making it difficult to simultaneously meet the industrial requirements of high yield, high purity, greenness, safety, and easy scale-up.
Hydroquinone is converted into disodium salt slurry, and a one-pot condensation reaction is carried out using a phase transfer catalyst and a green carbonate solvent to generate a two-armed chlorotriazine intermediate, which is then capped under alkaline conditions to avoid strong base side reactions, simplify the operation process and improve reaction selectivity.
It significantly improves reaction selectivity and yield, reduces inorganic salt formation, simplifies post-processing, is suitable for industrial-scale production, and significantly improves product purity and color.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of compound preparation technology, and in particular to a method for synthesizing 1,4-bis[4',6'-bis(4-n-propylphenoxy)-1',3',5'-triazine-2'-oxy]benzene. Background Technology
[0002] Functional organic compounds containing aromatic and heterocyclic structures, especially those containing triazine rings and aryloxy groups, are widely used in the fields of synthetic resin modification, stabilizers, and functional additives due to their excellent heat resistance, migration resistance, and compatibility with resin systems. In existing technologies, these compounds are typically prepared by nucleophilic substitution reactions of aromatic phenolic compounds with reactive halogenated heterocycles (such as chlorotriazine) under alkaline conditions, or by constructing the target molecular skeleton through multi-step reactions such as etherification and reduction of nitro compounds. While these methods can obtain the target structure, they generally suffer from problems such as numerous reaction steps, demanding solvent and alkaline systems, and complex post-processing, placing high demands on equipment, environmental protection, and cost control during industrial scale-up.
[0003] Among the existing publicly available technologies, patent CN116406399A discloses a class of compounds that can improve the performance of synthetic resins and their application as resin additives. By introducing specific monovalent aryl and divalent linking groups into the molecular structure, the mechanical and processing properties of the resin are improved. Patent CN120698915A provides a method for synthesizing o-aminothiophenol, which utilizes a strongly basic anion exchange resin to form a salt with thiophenol, promoting the main reaction and inhibiting side reactions, thereby obtaining a high yield and high purity product. Patent CN109956877A discloses a method for synthesizing 1,3-bis(3-aminophenoxy)benzene, which prepares the target product through an aromatic nucleophilic substitution reaction and a subsequent hydrogenation reduction step, and has the advantages of readily available raw materials and high purity.
[0004] However, the above-mentioned technical solutions still have certain shortcomings. CN116406399A mainly focuses on the compound structure and its application performance, with less attention paid to the synthetic route and process scale-up friendliness of key intermediates, and the purity is low. Although CN120698915A can obtain high-purity products, the ion exchange resin system used has a limited range of applicable raw materials and is difficult to directly extend to the construction of polyfunctional aryloxy heterocyclic compounds. CN109956877A requires a reduction step of nitro compounds, the reaction process is relatively long, and it involves hydrogenation operations, which puts higher requirements on safety and equipment conditions.
[0005] In summary, existing technologies for preparing structurally complex functional compounds generally suffer from problems such as numerous reaction steps, large quantities of highly polar or high-boiling-point solvents, high inorganic salt loading, high system viscosity, and difficult post-processing. These limitations make it difficult to simultaneously achieve high yields, high purity, and the industrial requirements of being green, safe, and easily scalable. Therefore, there is an urgent need to develop a novel synthetic method with a clear reaction pathway, mild conditions, a green solvent system, simplified operation, and suitability for industrial scale-up to meet the practical needs of the high-performance resin additive field for the large-scale preparation of such compounds. Summary of the Invention
[0006] To address the shortcomings of existing technologies, this invention aims to provide a method for synthesizing 1,4-bis[4',6'-bis(4-n-propylphenoxy)-1',3',5'-triazine-2'-oxy]benzene.
[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A method for synthesizing 1,4-bis[4',6'-bis(4-n-propylphenoxy)-1',3',5'-triazine-2'-oxy]benzene, comprising the following steps: Step 1: Convert hydroquinone into disodium hydroquinone under alkaline conditions; Step 2: Prepare an intermediate by reacting cyanuric chloride with 4-propylphenol; Step 3: In the presence of a phase transfer catalyst, the disodium hydroquinone salt undergoes a condensation reaction with the intermediate to generate a two-armed chlorotriazine intermediate with hydroquinone as a bridge. Step 4: The bi-arm chlorotriazine intermediate is subjected to an end-capping reaction with 4-propylphenol under alkaline conditions to obtain the final product.
[0008] In step 1, hydroquinone reacts with alkali in a mixed solvent of water and alcohol to generate disodium hydroquinone, and the disodium hydroquinone is directly used in subsequent reactions in the form of a slurry.
[0009] In step 1, the alkali is sodium hydroxide, the molar ratio of hydroquinone to sodium hydroxide is 1:2.0-2.2, the volume ratio of water to alcohol is 0.5-2:0.5-2, and the alcohol is anhydrous ethanol; the alkali is added at a temperature of 20-40℃, the alkali is added dropwise over a time of 20-60 minutes, and after the addition is complete, the reaction continues at 20-40℃ for 0.5-2 hours.
[0010] In step 2, the cyanuric chloride reacts with 4-propylphenol in a carbonate solvent and is carried out in the presence of an organic base to control the monosubstituted reaction of the cyanuric chloride.
[0011] The carbonate solvent is at least one of propylene carbonate or dimethyl carbonate, the organic base is triethylamine, the molar ratio of cyanuric chloride to 4-propylphenol is 1:0.95-1.05; the molar ratio of cyanuric chloride to organic base is 1:0.95-1.10; the reaction temperature is 0-5℃, the mixture of 4-propylphenol and organic base is added dropwise over 30-90 minutes, and after the addition is completed, the reaction continues at 0-10℃ for 0.5-2 hours to obtain the intermediate.
[0012] The phase transfer catalyst in step 3 is selected from quaternary ammonium salt phase transfer catalysts.
[0013] Preferably, the quaternary ammonium salt phase transfer catalyst is selected from at least one of tetrabutylammonium bromide, benzyltriethylammonium chloride, and hexadecyltrimethylammonium bromide.
[0014] More preferably, the quaternary ammonium salt phase transfer catalyst in step 3 is tetrabutylammonium bromide.
[0015] The molar ratio of the disodium hydroquinone salt to the intermediate is 1:1.9-2.1; the molar ratio of the disodium hydroquinone salt to the phase transfer catalyst is 1:0.01-0.05; the reaction temperature of the condensation reaction is 50-70℃; the addition time of the disodium hydroquinone salt is 30-90 min; and the reaction continues for 2-5 h after the addition is completed.
[0016] Steps 3 and 4 are carried out sequentially in the same reaction system. The generated inorganic salt precipitates out in solid form and is separated by filtration. In step 4, the molar ratio of the bi-arm chlorotriazine intermediate to 4-propylphenol is 1:2.0-2.2, and the molar ratio of the bi-arm chlorotriazine intermediate to the base is 1:2.0-2.5. The end-capping reaction is carried out at a temperature of 60-80℃ for 2-6 hours. After the reaction in step 4 is completed, the mixture is cooled to 20-30℃, the inorganic salt is removed by filtration, and the product is obtained by precipitation with water, washing, and recrystallization.
[0017] The end-capping reaction in step 4 is carried out under alkaline conditions provided by an alkali, which is anhydrous sodium carbonate. After the reaction is completed, the product is obtained by adding water to precipitate, washing, recrystallizing, filtering and drying. The recrystallization is carried out in a carbonate solvent, which is propylene carbonate. The dissolution temperature is 70-90℃, the drying temperature is 50-70℃, and the drying time is 8-16h.
[0018] Preferably, the method for synthesizing 1,4-bis[4',6'-bis(4-n-propylphenoxy)-1',3',5'-triazine-2'-oxy]benzene is as follows: Step 1: Preparation of disodium hydroquinone In a mechanically stirred reactor, deionized water and anhydrous ethanol were added and stirred. Hydroquinone was then added to the system and, after complete dissolution, sodium hydroxide aqueous solution was slowly added dropwise. After the addition was completed, stirring was continued to obtain disodium hydroquinone slurry, which was used directly for the next reaction without filtration or drying. Step 2, Preparation of intermediates In another dry reaction vessel, propylene carbonate was added and cooled. Cyanuryl chloride was added under stirring and the temperature was maintained. Then, 4-propylphenol and triethylamine were premixed and added dropwise to the above reaction system. After the addition was completed, the reaction was continued to obtain a solution of the intermediate in propylene carbonate. Step 3: Condensation to generate a two-armed chlorotriazine intermediate. In the reaction system obtained in step 2, tetrabutylammonium bromide is added, and then the temperature is raised. At this temperature, the hydroquinone disodium salt slurry obtained in step 1 is added to the reaction vessel. After the addition is completed, the reaction is stirred to generate a double-armed chlorotriazine intermediate with hydroquinone as the bridge. The sodium chloride generated during the reaction is precipitated in solid form and removed by filtration. Step 4: End-capping reaction and product acquisition Maintaining the reaction system at a high temperature, 4-propylphenol and anhydrous sodium carbonate were added to it all at once, and the reaction continued to complete the end-capping reaction of the two-arm chlorotriazine intermediate. After the reaction was completed, the mixture was cooled, and the inorganic salts were removed by filtration. The filtrate was poured into deionized water, and a large amount of white solid was precipitated by stirring. After filtration, the solid was washed with deionized water and then with anhydrous ethanol. The obtained solid was dissolved in propylene carbonate, cooled to crystallize, filtered, and dried to obtain a white solid product.
[0019] The structural formula of the 1,4-bis[4',6'-bis(4-n-propylphenoxy)-1',3',5'-triazine-2'-oxy]benzene is as follows:
[0020] The reaction mechanism and reaction formula of this invention are as follows: Under alkaline conditions, the two phenolic hydroxyl groups in the hydroquinone molecule exhibit strong acidity and can undergo an acid-base neutralization reaction with sodium hydroxide. With the gradual addition of sodium hydroxide, the two phenolic hydroxyl groups successively lose protons, forming corresponding phenoxy anions, which then combine with sodium ions to form disodium hydroquinone. This reaction is essentially a proton transfer reaction and does not involve the breaking or rearrangement of the molecular skeleton. Using a water / alcohol mixed solvent facilitates the dissolution of hydroquinone and the uniform dispersion of the alkali. The resulting disodium hydroquinone exists as a fine solid or slurry, exhibiting strong nucleophilicity, providing an active intermediate for subsequent nucleophilic substitution reactions with chlorotriazine.
[0021] The reaction formula is as follows:
[0022] The 1,3,5-triazine ring in the cyanuryl chloride molecule exhibits significant electronic defect characteristics, and the chlorine atom, as a favorable leaving group, readily undergoes nucleophilic substitution reactions. Under low-temperature conditions, 4-propylphenol is converted to a phenoxide anion in the presence of an organic base. This phenoxide acts as a nucleophile, attacking the carbon atom on the triazine ring and replacing one of the chlorine atoms, generating a monosubstituted intermediate. By controlling the reaction temperature and the molar ratio of the reactants, the occurrence of multi-substitution reactions can be effectively suppressed, keeping the reaction at the monosubstituted stage and providing a reaction site for the subsequent construction of a symmetrical two-arm structure.
[0023] The reaction formula is as follows:
[0024] In the presence of a phase-transfer catalyst, the phenoxy anions in disodium hydroquinone transfer from the aqueous phase to the organic phase, coming into full contact with the intermediate obtained in step 2. The disodium hydroquinone molecule contains two active phenoxy anions, which can undergo nucleophilic substitution reactions on the chlorine atoms of the two chlorotriazine molecules, thereby introducing two triazine groups at the 1,4-positions of the hydroquinone skeleton, forming a two-arm chlorotriazine intermediate bridged by hydroquinone. This step is a typical nucleophilic substitution reaction of aryloxy anions on activated halotriazines, with sodium chloride as a byproduct.
[0025] The reaction formula is as follows:
[0026] Under alkaline conditions, 4-propylphenol is activated to a phenoxy anion, which acts as a nucleophile to further attack the remaining active chlorine atom in the two-armed chlorotriazine intermediate, completing the substitution reaction at the remaining reaction sites on the triazine ring, thus achieving end-capping. As all chlorine atoms are replaced by phenoxy groups, the triazine ring structure tends to stabilize, ultimately forming 1,4-bis[4',6'-bis(4-n-propylphenoxy)-1',3',5'-triazine-2'-oxy]benzene. After the reaction, inorganic salts and a small amount of unreacted matter are removed by water precipitation, washing, and recrystallization to obtain the target product with a well-defined structure and high purity.
[0027] The reaction formula is as follows:
[0028] In the synthesis process of this invention, in addition to the main reactants, several excipients are introduced to synergistically achieve efficient and controllable reaction. Triethylamine, as an organic base, is used to activate 4-propylphenol and promptly neutralize the hydrogen chloride generated during the reaction, thereby controlling the monosubstituted reaction of cyanuric chloride and preventing system acidification. Tetrabutylammonium bromide, as a phase transfer catalyst, effectively transfers phenoxy anions from the aqueous phase to the organic phase by forming hydrophobic ion pairs, significantly improving the interphase reaction rate. Anhydrous sodium carbonate, as a mild base, promotes the formation of phenoxy anions from 4-propylphenol in the end-capping step, while avoiding the destruction of the triazine ring structure by strong bases. A water / alcohol mixed solvent is used in step one to improve the dissolution and deprotonation conditions of hydroquinone, forming a stable and controllable disodium salt slurry. Carbonate solvents, as reaction media, ensure good solubility of the reactants, do not participate in side reactions, and facilitate the precipitation of inorganic salts and post-processing operations, thus collectively supporting the overall efficiency and industrial feasibility of the process of this invention.
[0029] Compared with the prior art, the present invention has the following beneficial technical effects: 1) This invention significantly improves the nucleophilic reactivity of phenolic anions by pre-converting hydroquinone into a stable disodium salt slurry, avoids side reactions of free phenol under strong alkaline conditions, thereby reducing the amount of inorganic salts generated and improving reaction selectivity and overall yield.
[0030] 2) This invention introduces 4-n-propylphenoxy monochlorotriazine intermediate and carries out a one-pot condensation reaction in a carbonate-based green solvent, which effectively controls the degree of substitution, reduces multiple reactor changes, shortens the reaction and post-processing time, and reduces the viscosity of the system, thus significantly improving the process stability.
[0031] 3) Compared with existing processes using DMF, NMP and chlorinated solvents, this invention uses green carbonate solvents and a phase transfer catalytic system, which makes the generated inorganic salts easier to precipitate and filter. The resulting filter cake is loose, the filtration speed is fast, and the color and purity of the product are significantly improved, making it more suitable for industrial-scale production.
[0032] 4) This invention selects tetrabutylammonium bromide as a phase transfer catalyst, which has a high degree of matching and can efficiently promote the transfer of phenolic anions to the organic phase, improve the interphase reaction rate and the efficiency of simultaneous substitution of the two arms, and is significantly better than other quaternary ammonium salt catalysts. Detailed Implementation
[0033] All raw materials used in the embodiments of this invention are commercially available products.
[0034] Example 1 A method for synthesizing 1,4-bis[4',6'-bis(4-n-propylphenoxy)-1',3',5'-triazine-2'-oxy]benzene is as follows: Step 1: Preparation of disodium hydroquinone In a mechanically stirred reactor, 300 mL of deionized water and 300 mL of anhydrous ethanol were added and stirred at 25 °C. 110.1 g of hydroquinone was added to the system and completely dissolved. Then, 266.7 g of a 30% sodium hydroxide aqueous solution was slowly added dropwise at 30 °C for 30 min. After the addition was completed, the mixture was stirred at 30 °C for 1 h to obtain a disodium hydroquinone slurry. This slurry was used directly in the next reaction without filtration or drying. Step 2, Preparation of intermediates Add 800 mL of propylene carbonate to another dry reaction vessel, cool to 0 °C, add 184.4 g of cyanuric chloride under stirring, maintain the temperature at 2 °C, then add 136.2 g of 4-propylphenol and 101.2 g of triethylamine in advance to the above reaction system dropwise over 60 min. After the dropwise addition is completed, continue the reaction at 5 °C for 1 h to obtain a solution of the intermediate in propylene carbonate. Step 3: Condensation to generate a two-armed chlorotriazine intermediate. In the reaction system obtained in step 2, 6.5 g of tetrabutylammonium bromide was added, and then the temperature was raised to 60°C. At this temperature, the hydroquinone disodium salt slurry prepared in step 1 was slowly added to the reactor over 45 min. After the addition was completed, the reaction was continued to be stirred at 60°C for 3 h to generate a double-armed chlorotriazine intermediate with hydroquinone as the bridge. Sodium chloride generated during the reaction precipitated in solid form and was removed by filtration. Step 4: End-capping reaction and product acquisition The reaction system was kept at 70°C, and 272.4 g of 4-propylphenol and 212.0 g of anhydrous sodium carbonate were added at once. The reaction was continued at 70°C for 4 h to complete the end-capping reaction of the two-arm chlorotriazine intermediate. After the reaction was completed, the mixture was cooled to 25°C, and inorganic salts were removed by filtration. The filtrate was slowly poured into 3 L of deionized water, and a large amount of white solid was precipitated by stirring. After filtration, the solid was washed three times with deionized water and then once with anhydrous ethanol. The obtained solid was dissolved in propylene carbonate at 80°C, cooled to crystallize, filtered, and dried under vacuum at 60°C for 12 h to obtain a white solid product.
[0035] The obtained white solid product was subjected to... 1 H-NMR (CDCl3, 400MHz) analysis. The results are as follows: δ(v .s .TMS): 7.17-7.13 (m, 8H), 7.11-7.09 (m, 4H), 7.07-6.99 (m, 8H), 2.55 (t, J = 7.9 Hz, 8H), 1.61 (dt, J = 7.9, 7.4 Hz, 8H), 0.92 (t, J = 7.4 Hz,12H) Example 2 The method for synthesizing 1,4-bis[4',6'-bis(4-n-propylphenoxy)-1',3',5'-triazine-2'-oxy]benzene is basically the same as that in Example 1, except that the propylene carbonate used in steps 2 and 4 is replaced with an equal volume of N,N-dimethylformamide.
[0036] The obtained white solid product was subjected to... 1 H-NMR (CDCl3, 400MHz) analysis. The results are as follows: δ(v .s .TMS): 7.18-7.14 (m, 8H), 7.12-7.10 (m, 4H), 7.08-6.99 (m, 8H), 2.56 (t, J = 7.8 Hz, 8H), 1.63 (dt, J = 7.8, 7.3 Hz, 8H), 0.94 (t, J = 7.3 Hz,12H) Example 3 The method for synthesizing 1,4-bis[4',6'-bis(4-n-propylphenoxy)-1',3',5'-triazine-2'-oxy]benzene is basically the same as that in Example 1, except that the propylene carbonate used in steps 2 and 4 is replaced with an equal volume of N-methylpyrrolidone.
[0037] The obtained white solid product was subjected to... 1 H-NMR (CDCl3, 400MHz) analysis. The results are as follows: δ(v .s .TMS): 7.17-7.13 (m, 8H), 7.11-7.10 (m, 4H), 7.07-6.98 (m, 8H), 2.54 (t, J = 7.9 Hz, 8H), 1.60 (dt, J = 7.9, 7.4 Hz, 8H), 0.91 (t, J = 7.5 Hz,12H) Example 4 The method for synthesizing 1,4-bis[4',6'-bis(4-n-propylphenoxy)-1',3',5'-triazine-2'-oxy]benzene is basically the same as that in Example 1, except that the tetrabutylammonium bromide in step 3 is replaced with an equal mass of benzyltriethylammonium chloride.
[0038] The obtained white solid product was subjected to... 1 H-NMR (CDCl3, 400MHz) analysis. The results are as follows: δ(v .s .TMS): 7.18-7.12 (m, 8H), 7.11-7.09 (m, 4H), 7.08-6.99 (m, 8H), 2.57 (t, J = 8.0 Hz, 8H), 1.64 (dt, J = 8.0, 7.3 Hz, 8H), 0.95 (t, J = 7.3 Hz,12H) Example 5 The method for synthesizing 1,4-bis[4',6'-bis(4-n-propylphenoxy)-1',3',5'-triazine-2'-oxy]benzene is basically the same as that in Example 1, except that the tetrabutylammonium bromide in step 3 is replaced with an equal mass of hexadecyltrimethylammonium bromide.
[0039] The obtained white solid product was subjected to... 1 H-NMR (CDCl3, 400MHz) analysis. The results are as follows: δ(v .s .TMS): 7.17-7.13 (m, 8H), 7.11-7.09 (m, 4H), 7.07-6.98 (m, 8H), 2.53 (t, J = 8.0 Hz, 8H), 1.60 (dt, J = 7.9, 7.2 Hz, 8H), 0.94 (t, J = 7.5 Hz,12H) Test Example 1 Yield test: After the reaction was completed and the product was recrystallized and dried under vacuum, the actual mass of the target product was weighed. Using cyanuric chloride as the limited reactant, the theoretical yield was calculated according to the theoretical molar mass of the target product. The ratio of the two yields was the yield of the target product, and the results were expressed as a mass percentage. The test results are shown in Table 1.
[0040] Table 1
[0041] Test Example 2 Purity test: The purity of the product was determined by high performance liquid chromatography (HPLC) under the following chromatographic conditions: Chromatographic column: C18 reversed-phase column (250mm × 4.6mm, 5μm) Mobile phase: Acetonitrile / water = 85 / 15 (volume ratio) Flow rate: 1.0 mL / min Detection wavelength: 254nm Column temperature: 30℃ The mass percentage of the target product was calculated using the area normalization method and used as the product purity. The test results are shown in Table 2.
[0042] Table 2
[0043] In Example 1 of this invention, propylene carbonate is used as a moderately polar, non-strongly coordinating solvent. It effectively dissolves the chlorotriazine intermediate without exhibiting the excessive solvation effect on phenoxy anions and quaternary ammonium salt ions seen with N,N-dimethylformamide and N-methylpyrrolidone, thus facilitating the nucleophilic substitution reaction. Simultaneously, the generated sodium chloride has low solubility in this solvent, easily precipitating and moving out of the reaction equilibrium, resulting in significantly improved yield and purity. In contrast, N,N-dimethylformamide and N-methylpyrrolidone have strong solubility for inorganic salts, high system viscosity, and increased probability of side reactions, leading to decreased efficiency. On the other hand, tetrabutylammonium bromide possesses moderate hydrophobicity and ion migration ability, efficiently transferring phenoxy anions to the organic phase while maintaining high reactivity; while benzyltriethylammonium chloride and hexadecyltrimethylammonium bromide either have insufficient ion pair stability or excessive steric hindrance, reducing effective mass transfer efficiency, and therefore their catalytic effect is inferior to tetrabutylammonium bromide.
Claims
1. A method for synthesizing 1,4-bis[4',6'-bis(4-n-propylphenoxy)-1',3',5'-triazine-2'-oxy]benzene, characterized in that, Includes the following steps: Step 1: Convert hydroquinone into disodium hydroquinone under alkaline conditions; Step 2: Prepare an intermediate by reacting cyanuric chloride with 4-propylphenol; Step 3: In the presence of a phase transfer catalyst, the disodium hydroquinone salt undergoes a condensation reaction with the intermediate to generate a two-armed chlorotriazine intermediate with hydroquinone as a bridge. Step 4: The bi-arm chlorotriazine intermediate is subjected to an end-capping reaction with 4-propylphenol under alkaline conditions to obtain the final product.
2. The synthesis method according to claim 1, characterized in that, In step 1, hydroquinone reacts with alkali in a mixed solvent of water and alcohol to generate disodium hydroquinone, and the disodium hydroquinone is directly used in subsequent reactions in the form of a slurry.
3. The synthesis method as described in claim 2, characterized in that, In step 1, the alkali is sodium hydroxide, the molar ratio of hydroquinone to sodium hydroxide is 1:2.0-2.2, the volume ratio of water to alcohol is 0.5-2:0.5-2, and the alcohol is anhydrous ethanol; the alkali is added at a temperature of 20-40℃, the alkali is added dropwise over a time of 20-60 minutes, and after the addition is complete, the reaction continues at 20-40℃ for 0.5-2 hours.
4. The synthesis method according to claim 1, characterized in that, In step 2, the cyanuric chloride reacts with 4-propylphenol in a carbonate solvent and is carried out in the presence of an organic base to control the monosubstituted reaction of the cyanuric chloride.
5. The synthesis method as described in claim 4, characterized in that, The carbonate solvent is at least one of propylene carbonate or dimethyl carbonate, the organic base is triethylamine, the molar ratio of cyanuric chloride to 4-propylphenol is 1:0.95-1.05; the molar ratio of cyanuric chloride to organic base is 1:0.95-1.10; the reaction temperature is 0-5℃, the mixture of 4-propylphenol and organic base is added dropwise over 30-90 minutes, and after the addition is completed, the reaction continues at 0-10℃ for 0.5-2 hours to obtain the intermediate.
6. The synthesis method according to claim 1, characterized in that, The phase transfer catalyst in step 3 is selected from quaternary ammonium salt phase transfer catalysts.
7. The synthesis method according to claim 6, characterized in that, In step 3, the quaternary ammonium salt phase transfer catalyst is tetrabutylammonium bromide; the molar ratio of disodium hydroquinone to the intermediate is 1:1.9-2.1; the molar ratio of disodium hydroquinone to the phase transfer catalyst is 1:0.01-0.05; the reaction temperature of the condensation reaction is 50-70℃; the addition time of disodium hydroquinone is 30-90 min; and the reaction continues for 2-5 h after the addition is completed.
8. The synthesis method according to claim 1, characterized in that, Steps 3 and 4 are carried out sequentially in the same reaction system. The generated inorganic salt precipitates out in solid form and is separated by filtration. In step 4, the molar ratio of the bi-arm chlorotriazine intermediate to 4-propylphenol is 1:2.0-2.2, and the molar ratio of the bi-arm chlorotriazine intermediate to the base is 1:2.0-2.
5. The end-capping reaction is carried out at a temperature of 60-80℃ for 2-6 hours. After the reaction in step 4 is completed, the mixture is cooled to 20-30℃, the inorganic salt is removed by filtration, and the product is obtained by precipitation with water, washing, and recrystallization.
9. The synthesis method as described in claim 8, characterized in that, The end-capping reaction in step 4 is carried out under alkaline conditions provided by an alkali, which is anhydrous sodium carbonate. After the reaction is completed, the product is obtained by adding water to precipitate, washing, recrystallizing, filtering and drying. The recrystallization is carried out in a carbonate solvent, which is propylene carbonate. The dissolution temperature is 70-90℃, the drying temperature is 50-70℃, and the drying time is 8-16h.