Synthesis method of 4, 6-bis (2, 4-dimethylphenyl)-2-(2, 4-dihydroxyphenyl)-1, 3, 5-triazine

Abstract

The invention belongs to the technical field of organic synthesis, and particularly relates to a synthesis method of an intermediate 4, 6-bis (2, 4-dimethylphenyl)-2-(2, 4-dihydroxyphenyl)-1, 3, 5-triazine of a triazine ultraviolet light absorber, cyanuric chloride, m-xylene and resorcinol are used as raw materials, a Friedel-Crafts alkylation reaction is performed under the action of a catalyst to obtain a target product, the yield is greater than or equal to 92.0%, and the yield is greater than or equal to 92.0%. The purity is more than or equal to 99%, the chromaticity is less than or equal to 5 and the light transmittance The method provided by the invention is a simple, convenient and efficient method for synthesizing 4, 6-bis (2, 4-dimethylphenyl)-2-(2, 4-dihydroxyphenyl)-1, 3, 5-triazine, the product quality is good, and the method has better technical economy and industrial application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and particularly relates to a method for synthesizing 4,6-bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine, an intermediate of a triazine ultraviolet absorber. Background Art

[0002] Currently, the main UV absorbers used in polymer materials include benzotriazoles, benzophenones, salicylates, and triazines. Benzotriazoles are the most widely used and have the widest application range. Compared to benzotriazoles, triazines are the newest class of UV absorbers. They offer advantages such as high efficiency, low color, high processing temperatures, good compatibility, and excellent broad-spectrum properties. These advantages have made triazines the leading UV absorber development direction.

[0003] With the European Chemicals Agency's inclusion of four benzotriazole UV absorbers (UV-320, UV-327, UV-328, and UV-350) on the Substances of Very High Concern list in 2014 and 2015, their use has been strictly restricted. Consequently, benzotriazole UV absorbers are gradually being replaced, while the research and development and production of triazine UV absorbers are expanding. Currently, few Chinese companies possess the technology to produce triazine UV absorbers, and many are still in the R&D stage. Consequently, the demand for R&D in this area is increasing.

[0004] 4,6-Bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine, CAS: 1668-53-7, molecular weight 397.48, pale yellow powder, melting point 197.5-198.5°C. It is a common intermediate for the triazine UV absorbers UV-1164 (CAS: 2725-22-6), UV-400 (CAS: 153519-44-9; 107-98-2), and UV-405 (CAS: 137658-79-8). To obtain high-quality finished products of these three triazine UV absorbers, this intermediate must have a high content, transmittance, and color.

[0005] In the prior art, there are three main synthetic routes for 4,6-bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine. Route 1: cyanuric chloride is subjected to a five-step reaction of amination, condensation, alkaline hydrolysis, chlorination, and condensation to obtain the target product. This route has many steps, is cumbersome to operate, and produces a large amount of three wastes. Route 2: cyanuric chloride is subjected to a Grignard reaction and a Friedel-Crafts alkylation reaction to obtain the target product. The disadvantage of this route is that the Grignard reaction is used and the reaction conditions are harsh. Route 3: cyanuric chloride is first reacted with m-xylene through a Friedel-Crafts alkylation reaction to obtain an intermediate, which is then reacted with resorcinol through a Friedel-Crafts alkylation reaction to obtain the target product.

[0006] The Friedel-Crafts reaction synthesis method mainly comprises: first, using cyanuric chloride and m-xylene as raw materials, chlorobenzene as a reaction solvent, and anhydrous aluminum chloride as a catalyst (added in five portions), reacting in an ice bath, destroying the reaction with 2% hydrochloric acid, separating the liquids, extracting, distilling, crystallizing, and filtering to obtain an intermediate (yield 87.6%); then, reacting the intermediate with resorcinol under the catalysis of anhydrous aluminum chloride (added in five portions) at 80° C., destroying the reaction with 2% hydrochloric acid, distilling, filtering while hot, and recrystallizing the crude product twice from toluene to obtain a light yellow target product (yield 95.1%). The total yield of the two-step reaction is 83.3%. Or use cyanuric chloride and m-xylene as raw materials, chlorobenzene as reaction solvent, anhydrous aluminum chloride as catalyst (added in 5 times), concentrated hydrochloric acid as promoter, add resorcinol to the reaction bottle after the ice bath reaction is completed, and after the reaction is complete at 80°C, destroy it with 2% hydrochloric acid water, distill and filter while hot, and recrystallize the crude product twice from toluene to obtain a light yellow target product with a yield of 84.4% (Li Yu'an. Research on the synthesis of ultraviolet absorber UV-400 and related substances [D]. Zhejiang Sci-Tech University, 2021. DOI: 10.27786 / d.cnki.gzjlg.2021.000729.).

[0007] Using cyanuric chloride, m-xylene and resorcinol as raw materials, chlorobenzene as reaction solvent, anhydrous aluminum chloride as catalyst and concentrated hydrochloric acid as promoter, the target product was obtained by a two-step Friedel-Crafts alkylation reaction in one pot. The post-treatment method was as follows: after the reaction, the reaction solution was cooled to room temperature, crushed ice, water and hydrochloric acid were added to the reaction solution, and the mixture was stirred for 2 hours, then allowed to stand, precipitated, filtered and dried to obtain a crude product. The crude product was recrystallized from ethyl acetate-petroleum ether to obtain a pure product with a yield of 83% (Ji Jinling, Sun Lijiao, Huang Shanshan, et al. Process development of ultraviolet absorber UV-1164 [J]. Chemical Industry Times, 2023, 37(02): 26-29. DOI: 10.16597 / j.cnki.issn.1002-154x.2023.02.007.).

[0008] The Friedel-Crafts alkylation reaction route reported in patent CN113968825B uses chlorobenzene or o-dichlorobenzene as a solvent, anhydrous aluminum chloride or ferric chloride as a catalyst, and m-xylene is added dropwise twice (first at 70-90°C for 3-4 hours, then at 30-35°C for 6-7 hours). After the completion of the one-step Friedel-Crafts reaction, the temperature is lowered to below 40°C, and resorcinol is added. After the reaction at 70°C for 6 hours, water is added for hydrolysis, phase separation is performed, and recrystallization is performed at 5-10°C to obtain the target product.

[0009] The above preparation method has the following problems: the catalyst anhydrous aluminum chloride needs to be added in portions, which is cumbersome to operate; a large amount of hydrochloric acid water is required during post-treatment, which produces a large amount of acidic wastewater, and the wastewater needs to be filtered while hot, which is not suitable for industrialization (the higher the temperature under acidic conditions, the more serious the corrosion to the equipment); two recrystallizations are required, which is cumbersome and time-consuming; a low yield; and a solubility problem that the target product cannot normally phase separate in the system of o-dichlorobenzene / chlorobenzene and water. Summary of the Invention

[0010] To solve the above problems, the present invention discloses a method for synthesizing 4,6-bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine. The method can achieve a simple and efficient preparation of high-quality 4,6-bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine.

[0011] To achieve the above object, the technical solution of the present invention is as follows:

[0012] The present invention provides a method for synthesizing 4,6-bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine, comprising the following steps:

[0013] (1) One-step Friedel-Crafts reaction: Start stirring the Friedel-Crafts reactor, protect with nitrogen, add solvent 1, cyanuric chloride and anhydrous aluminum chloride, stir at 0-30°C for 0.5-2h, then add 36% hydrochloric acid and continue to keep warm and stir for 0.5-1h, then add m-xylene dropwise, keep warm and react for 6-12h after the addition is complete; m-xylene is added dropwise twice, with an interval of 0.5-1h in between;

[0014] (2) Two-step Friedel-Crafts reaction: add resorcinol to the one-step Friedel-Crafts reaction solution, then heat to 50-80°C and keep the reaction for 4-8 hours;

[0015] (3) Water washing and distillation: After the reaction is completed, an alcohol aqueous solution is added dropwise to the reaction liquid (or the reaction liquid is added dropwise to the alcohol aqueous solution), and the reaction liquid is allowed to stand for separation and then washed with water until neutral. The reaction liquid after washing is distilled at 100-110°C under negative pressure (vacuum degree ≤ 10 kPa) to remove alcohol and water; the alcohol is isopropyl alcohol or isobutyl alcohol;

[0016] (4) Decolorization and crystallization: Then add a decolorizer and keep warm for decolorization. After decolorization is completed, remove the decolorizer by hot filtration and add solvent 2. Heat to dissolve and then slowly cool to 10-20°C for solid-liquid separation. Vacuum dry (vacuum degree ≤ 10 kPa) to obtain the target product.

[0017] Furthermore, in the step (1), the solvent 1 is chlorobenzene or o-dichlorobenzene, and the mass volume ratio of cyanuric chloride to the solvent 1 is 1:10-15.

[0018] Furthermore, in step (1), the mass ratio of hydrochloric acid to cyanuric chloride is 0.05-0.10:1.

[0019] Furthermore, in the step (1), the molar ratio of anhydrous aluminum chloride to cyanuric chloride is 3-3.5:1, and the molar ratio of m-xylene to cyanuric chloride is 1.95-2.05:1.

[0020] Furthermore, in the step (1), the time for adding xylene dropwise is 3-5 hours, and the dropping temperature and the insulation reaction temperature are 10-30°C.

[0021] Furthermore, in step (2), the molar ratio of resorcinol to cyanuric chloride is 1-1.05:1.

[0022] Furthermore, in step (3), the volume of the alcohol aqueous solution is 5-10 times the mass of cyanuric chloride, wherein the volume proportion of the alcohol is 50-60%.

[0023] Furthermore, the water washing temperature in step (3) is 70-80°C.

[0024] Furthermore, in step (4), the decolorizing agent is one of activated clay and activated carbon or a combination thereof, the amount of the decolorizing agent is 3-10% of the weight of the theoretically generated target product, the decolorizing temperature is 110-120° C., and the decolorizing time is 1-2 h.

[0025] Furthermore, in step (4), solvent 2 is n-heptane or cyclohexane, the volume ratio of solvent 2 to solvent 1 is 0.5-1:1, the crystallization cooling rate is 3-8°C / h, and the drying temperature is 100-120°C.

[0026] The beneficial effects of the present invention are:

[0027] (1) Since the water content of the reaction solvent required by the Format method is high and there is a risk of process accidents caused by peroxides during the solvent recovery process, the present invention adopts an alkylation reaction route to make the process safer, simpler to operate, and suitable for industrial production.

[0028] (2) The use of hydrochloric acid as a promoter in the Friedel-Crafts reaction increases the activity of the catalyst and greatly improves the product yield.

[0029] (3) After the Friedel-Crafts reaction, the aqueous alcohol solution is used for hydrolysis. Compared with the method of using hydrochloric acid water (or crushed ice, water and hydrochloric acid) or only using water for hydrolysis, the amount of water used is reduced and the generation of a large amount of hydrochloric acid wastewater is avoided.

[0030] (4) Based on the problem that the target product cannot be normally separated into phases in the system of o-dichlorobenzene / chlorobenzene and water, isopropanol or isobutanol is innovatively used as a solubilizing solvent. The catalyst can be removed by simply washing with water, which solves the problem of difficult solid-liquid separation (filtration or centrifugation) after acid hydrolysis. The operation is simple and efficient.

[0031] (5) By screening the solvent type and ratio, as well as the cooling rate, the problems of poor material fluidity and slow solid-liquid separation during cooling crystallization were solved, while taking into account the purity of the product (effectively removing the isomer impurities in the Friedel-Crafts reaction) and the yield.

[0032] (6) The target product has a yield of ≥92.0%, a purity of ≥99%, a chromaticity of ≤5, and a transmittance of ≥98.5%, reaching a relatively high level in the industry and having a good prospect for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a liquid phase spectrum of 4,6-bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine synthesized in Example 1 of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0035] Example 1:

[0036] After nitrogen replacement, 2000 L of o-dichlorobenzene was added to the Friedel-Crafts reactor, stirring was started, and 200 kg of cyanuric chloride (99%, molecular weight 184.41) and 477.22 kg of anhydrous aluminum chloride (99%, molecular weight 133.34) were added. After the additions were completed, stirring was continued at 10°C for 1 hour. Then, 14 kg of 36% hydrochloric acid was added. Stirring was continued for 0.5 hour. After that, 116.32 kg of m-xylene (98%, molecular weight 106.17) was added dropwise at a constant rate over 120 minutes. After the addition was completed, the temperature was kept at 20°C for 1 hour. Then, 116.32 kg of m-xylene (98%) was added dropwise at a constant rate over 120 minutes. After the addition was completed, the temperature was kept at 20°C for 8 hours. 119.42 kg of resorcinol (99%, molecular weight 110.11) was added to the one-step Friedel-Crafts reaction solution. After the additions were completed, the temperature was raised to 70°C and the reaction was kept at this temperature for 4 hours.

[0037] After the reaction, the reaction solution was transferred to a hydrolysis kettle, 1600 L of 50% isopropyl alcohol aqueous solution was added dropwise, the temperature was controlled at 75°C, the liquid was allowed to stand and separate, the organic layer was washed with water until neutral, and then the isopropyl alcohol and water were removed by vacuum distillation at 105°C.

[0038] After distillation, the material was transferred to a decolorization kettle, where 10 kg of activated clay and 5 kg of activated carbon were added. The mixture was stirred at 120°C for 1 hour for decolorization. The decolorized solution was then hot filtered and transferred to a crystallization kettle. 1600 L of cyclohexane was then added to the crystallization kettle. The temperature was raised until the solution was clear, then cooled to 15°C at a rate of 5°C / h. Solid-liquid separation was performed, and the product was vacuum-dried at 110°C to obtain the pale yellow target product. The yield was 93.8%, the purity was 99.5%, the color was 4, the transmittance was 98.8% (460 nm), the volatile matter was 0.06%, and the ash content was 0.04%.

[0039] The liquid phase spectrum of the obtained product is as follows Figure 1 shown.

[0040] Example 2:

[0041] After nitrogen displacement, 2400 mL of chlorobenzene was added to the Friedel-Crafts reactor. Stirring was initiated, followed by the addition of 200 g of cyanuric chloride and 462.76 g of anhydrous aluminum chloride. Stirring was continued at 5°C for 1 hour. Then, 16 g of 36% hydrochloric acid was added. Stirring was continued for 1 hour. After the addition was complete, 119.23 g of m-xylene was added dropwise at a constant rate over 60 minutes. The mixture was incubated for 0.5 hours. Then, 119.23 g of m-xylene was added dropwise at a constant rate over 120 minutes. The mixture was incubated at 15°C for 10 hours. 121.81 g of resorcinol was added to the one-step Friedel-Crafts reaction mixture. After the addition was complete, the mixture was heated to 60°C and incubated for 6 hours.

[0042] After the reaction, the reaction solution was transferred to a hydrolysis kettle, 1200 mL of 50% isobutanol aqueous solution was added dropwise, the temperature was controlled at 80°C, the liquid was allowed to stand and separate, the organic layer was washed with water until neutral, and then the isobutanol and water were removed by vacuum distillation at 100°C.

[0043] After distillation, the material was transferred to a decolorization kettle, where 17 g of activated carbon was added. The mixture was stirred at 110°C for 1 hour for decolorization. The decolorized solution was then hot filtered and transferred to a crystallization kettle. 1440 mL of n-heptane was then added to the crystallization kettle. The temperature was raised until the solution was clear, then cooled to 10°C at a rate of 3°C / h. Solid-liquid separation was performed, and the product was vacuum-dried at 120°C to obtain the pale yellow desired product. The yield was 93%, the purity was 99.46%, the color was 5, the transmittance was 99% (460 nm), the volatile matter was 0.08%, and the ash content was 0.03%.

[0044] Example 3:

[0045] After nitrogen displacement, 2800 mL of o-dichlorobenzene was added to the Friedel-Crafts reactor, stirring was initiated, and 200 g of cyanuric chloride and 506.14 g of anhydrous aluminum chloride were added. After addition, stirring was continued at 20°C for 2 h. Then, 10 g of 36% hydrochloric acid was added, stirring was continued for 0.5 h, and 117.49 g of m-xylene was added dropwise at a constant rate over 120 min. The temperature was maintained for 1 h, and then 117.49 g of m-xylene was added dropwise at a constant rate over 100 min. After addition, the temperature was maintained at 25°C for 6 h. 124.20 g of resorcinol was added to the one-step Friedel-Crafts reaction solution. After addition, the temperature was raised to 50°C and the reaction was maintained for 8 h.

[0046] After the reaction, the reaction solution was transferred to a hydrolysis kettle, and 2000 mL of 60% isopropyl alcohol aqueous solution was added dropwise. The temperature was controlled at 70°C, and the solution was allowed to stand for separation. The organic layer was washed with water until neutral. Then, the isopropyl alcohol and water were removed by vacuum distillation at 110°C.

[0047] After distillation, the material was transferred to a decolorization kettle, where 21 g of activated carbon was added. The mixture was stirred and decolorized at 115°C for 2 h. The decolorized solution was then hot filtered and transferred to a crystallization kettle. 2800 mL of cyclohexane was then added to the crystallization kettle. The temperature was raised until the solution was clear, then cooled to 20°C at a rate of 6°C / h. Solid-liquid separation was performed, and the product was dried under vacuum at 100°C to obtain the pale yellow desired product. The yield was 92.5%, the purity was 99.58%, the color was 3, the transmittance was 98.6% (460 nm), the volatile matter was 0.05%, and the ash content was 0.04%.

[0048] Example 4:

[0049] After nitrogen displacement, 3000 mL of chlorobenzene was added to the Friedel-Crafts reactor, stirring was initiated, and 200 g of cyanuric chloride and 448.30 g of anhydrous aluminum chloride were added. After addition, stirring was continued at 25°C for 1 hour. Then, 12 g of 36% hydrochloric acid was added, and stirring was continued for 1 hour. After 113.42 g of m-xylene was added dropwise at a constant rate over 130 minutes. The temperature was maintained for 0.5 hours. Then, 113.42 g of m-xylene was added dropwise at a constant rate over 170 minutes. After addition, the temperature was maintained at 30°C for 8 hours. 119.42 g of resorcinol was added to the one-step Friedel-Crafts reaction solution. After addition, the temperature was raised to 55°C and the reaction was maintained for 8 hours.

[0050] After the reaction, the reaction solution was transferred to a hydrolysis kettle, and 1400 mL of a 60% isobutanol aqueous solution was added dropwise. The temperature was controlled at 78°C, and the solution was allowed to stand for separation. The organic layer was washed with water until neutral. The isobutanol and water were then removed by vacuum distillation at 105°C.

[0051] After distillation, the mixture was transferred to a decolorization kettle, where 25 g of activated clay and 5 g of activated carbon were added. The mixture was stirred and decolorized at 115°C for 1 hour. The decolorized solution was then hot filtered and transferred to a crystallization kettle. 1500 mL of n-heptane was then added to the crystallization kettle. The temperature was raised until the solution was clear, then cooled to 15°C at a rate of 4°C / h. Solid-liquid separation was performed, and the product was vacuum-dried at 115°C to obtain the pale yellow target product. The yield was 92.7%, the purity was 99.42%, the color was 3, the transmittance was 98.7% (460 nm), the volatile matter was 0.08%, and the ash content was 0.03%.

[0052] Example 5:

[0053] After nitrogen displacement, 2200 mL of o-dichlorobenzene was added to the Friedel-Crafts reactor, stirring was initiated, and 200 g of cyanuric chloride and 491.68 g of anhydrous aluminum chloride were added. After addition, stirring was continued at 30°C for 0.5 h. Then, 20 g of 36% hydrochloric acid was added, and stirring was continued for 0.5 h. After that, 114.58 g of m-xylene was added dropwise at a constant rate over 150 min. The temperature was maintained for 0.5 h. Then, 114.58 g of m-xylene was added dropwise at a constant rate over 150 min. After addition, the temperature was maintained at 10°C for 12 h. 125.39 g of resorcinol was added to the one-step Friedel-Crafts reaction solution. After addition, the temperature was raised to 65°C and the reaction was maintained for 6 h.

[0054] After the reaction, the reaction solution was transferred to a hydrolysis kettle, 1000 mL of 55% isopropyl alcohol aqueous solution was added dropwise, the temperature was controlled at 72°C, the liquid was allowed to stand and separate, the organic layer was washed with water until neutral, and then the isopropyl alcohol and water were removed by vacuum distillation at 110°C.

[0055] After distillation, the material was transferred to a decolorization kettle, where 38.4 g of activated carbon was added. The mixture was stirred and decolorized at 110°C for 2 h. The decolorized solution was then hot filtered and transferred to a crystallization kettle. 2200 mL of cyclohexane was then added to the crystallization kettle. The temperature was raised until the solution was clear, then cooled to 20°C at a rate of 8°C / h. Solid-liquid separation was performed, and the product was vacuum-dried at 105°C to obtain the pale yellow desired product. The yield was 93.4%, the purity was 99.4%, the color was 4, the transmittance was 99.2% (460 nm), the volatile matter was 0.06%, and the ash content was 0.05%.

[0056] Example 6:

[0057] After nitrogen displacement, 2600 mL of chlorobenzene was added to the Friedel-Crafts reactor. Stirring was initiated, followed by the addition of 200 g of cyanuric chloride and 455.53 g of anhydrous aluminum chloride. Stirring was continued at 0°C for 2 h. Then, 18 g of 36% hydrochloric acid was added. Stirring was continued for 1 h. After this addition, 115.15 g of m-xylene was added dropwise at a constant rate over 60 min. The mixture was incubated for 1 h. Then, 115.15 g of m-xylene was added dropwise at a constant rate over 180 min. The mixture was incubated at 15°C for 8 h. 123 g of resorcinol was added to the one-step Friedel-Crafts reaction mixture. After this addition, the mixture was heated to 80°C and incubated for 4 h.

[0058] After the reaction, the reaction solution was transferred to a hydrolysis kettle, and 1800 mL of 55% isobutanol aqueous solution was added dropwise. The temperature was controlled at 76°C for standing to separate the liquids. The organic layer was washed with water until neutral. Then, the isobutanol and water were removed by vacuum distillation at 100°C.

[0059] After distillation, the material was transferred to a decolorization kettle, where 25.6 g of activated carbon was added. The mixture was stirred and decolorized at 120°C for 2 h. The decolorized solution was then hot filtered and transferred to a crystallization kettle. 1820 mL of n-heptane was then added to the crystallization kettle. The temperature was raised until the solution was clear, then cooled to 10°C at a rate of 7°C / h. Solid-liquid separation was performed, and the product was dried under vacuum at 120°C to obtain the pale yellow desired product. The yield was 92.6%, the purity was 99.52%, the color was 5, the transmittance was 98.8% (460 nm), the volatile matter was 0.06%, and the ash content was 0.04%.

[0060] Example 7:

[0061] After nitrogen displacement, 2400 mL of o-dichlorobenzene was added to the Friedel-Crafts reactor. Stirring was initiated, followed by the addition of 200 g of cyanuric chloride and 484.45 g of anhydrous aluminum chloride. Stirring was continued at 0°C for 1 hour. Then, 16 g of 36% hydrochloric acid was added, followed by stirring for 0.5 hour. After this addition, 114 g of m-xylene was added dropwise at a constant rate over 80 minutes. The mixture was then incubated for 1 hour. Then, 114 g of m-xylene was added dropwise at a constant rate over 170 minutes. The mixture was incubated at 25°C for 10 hours. 119.42 g of resorcinol was added to the one-step Friedel-Crafts reaction mixture. After this addition, the mixture was heated to 75°C and incubated for 6 hours.

[0062] After the reaction, the reaction solution was transferred to a hydrolysis kettle, 1200 mL of 52% isopropyl alcohol aqueous solution was added dropwise, the temperature was controlled at 70°C, the liquid was allowed to stand for separation, the organic layer was washed with water until neutral, and then the isopropyl alcohol and water were removed by vacuum distillation at 105°C.

[0063] After distillation, the material was transferred to a decolorization kettle, where 20 g of activated clay and 13.3 g of activated carbon were added. The mixture was stirred at 115°C for 2 h for decolorization. The decolorized solution was then hot filtered and transferred to a crystallization kettle. 2160 mL of cyclohexane was then added to the crystallization kettle. The temperature was raised until the solution was clear, then cooled to 20°C at a rate of 5°C / h. Solid-liquid separation was then performed, and the product was dried under vacuum at 110°C to obtain the pale yellow desired product. The yield was 93.2%, the purity was 99.6%, the color was 4, the transmittance was 98.7% (460 nm), the volatile matter was 0.1%, and the ash content was 0.05%.

[0064] Example 8:

[0065] After nitrogen displacement, 2000 mL of chlorobenzene was added to the Friedel-Crafts reactor. Stirring was initiated, followed by the addition of 200 g of cyanuric chloride and 498.91 g of anhydrous aluminum chloride. Stirring was continued at 15°C for 0.5 h. Then, 13 g of 36% hydrochloric acid was added. Stirring was continued for 1 h. Then, 118 g of m-xylene was added dropwise at a constant rate over 100 min. The temperature was maintained for 0.5 h. Then, 118 g of m-xylene was added dropwise at a constant rate over 100 min. The temperature was maintained at 30°C for 10 h. 121.81 g of resorcinol was added to the one-step Friedel-Crafts reaction mixture. After addition, the temperature was raised to 70°C and the reaction was maintained for 8 h.

[0066] After the reaction, the reaction solution was transferred to a hydrolysis kettle, 1600 mL of 54% isobutanol aqueous solution was added dropwise, the temperature was controlled at 80°C, the liquid was allowed to stand for separation, the organic layer was washed with water until neutral, and then the isobutanol and water were removed by vacuum distillation at 110°C.

[0067] After distillation, the material was transferred to a decolorization kettle, where 20.5 g of activated carbon was added. The mixture was stirred and decolorized at 120°C for 1.5 h. The decolorized solution was then hot filtered and transferred to a crystallization kettle. 1500 mL of n-heptane was then added to the crystallization kettle. The temperature was raised until the solution was clear, then cooled to 15°C at a rate of 8°C / h. Solid-liquid separation was performed, and the product was vacuum-dried at 105°C to obtain the pale yellow desired product. The yield was 93.5%, the purity was 99.65%, the color was 3, the transmittance was 99% (460 nm), the volatile matter was 0.09%, and the ash content was 0.03%.

[0068] Comparative Example 1:

[0069] After nitrogen displacement, 2400 mL of chlorobenzene was added to the Friedel-Crafts reactor, stirring was initiated, and 200 g of cyanuric chloride and 462.76 g of anhydrous aluminum chloride were added. After addition, stirring was continued at 5°C for 1 hour. Then, 119.23 g of m-xylene was added dropwise at a constant rate over 60 minutes. The temperature was maintained for 0.5 hours. Then, 119.23 g of m-xylene was added dropwise at a constant rate over 120 minutes. After addition, the temperature was maintained at 15°C for 10 hours. 121.81 g of resorcinol was added to the one-step Friedel-Crafts reaction solution. After addition, the temperature was raised to 60°C and the reaction was continued for 6 hours.

[0070] After the reaction, the reaction solution was transferred to a hydrolysis kettle, 1200 mL of 50% isobutanol aqueous solution was added dropwise, the temperature was controlled at 80°C, the liquid was allowed to stand and separate, the organic layer was washed with water until neutral, and then the isobutanol and water were removed by vacuum distillation at 100°C.

[0071] After distillation, the material was transferred to a decolorization kettle, where 17 g of activated carbon was added. The mixture was stirred at 110°C for 1 hour for decolorization. The decolorized solution was then hot filtered and transferred to a crystallization kettle. 1440 mL of n-heptane was then added to the crystallization kettle. The temperature was raised until the solution was clear, then cooled to 10°C at a rate of 3°C / h. Solid-liquid separation was performed, and the product was dried under vacuum at 120°C to obtain the pale yellow desired product. The yield was 64%, the purity was 96.8%, the color was 8, the transmittance was 95% (460 nm), the volatile matter was 0.07%, and the ash content was 0.05%.

[0072] Comparative Example 2:

[0073] After nitrogen displacement, 2400 mL of chlorobenzene was added to the Friedel-Crafts reactor, stirring was started, and 200 g of cyanuric chloride and 462.76 g of anhydrous aluminum chloride were added. After addition, stirring was continued at 5°C for 1 hour. Then, 16 g of 36% hydrochloric acid was added. After stirring for 1 hour, the temperature was controlled at 0-5°C and 119.23 g of m-xylene was added dropwise at a constant rate over 60 minutes. After the addition was complete, the temperature was maintained at 5°C for 0.5 hours. Then, 119.23 g of m-xylene was added dropwise at a constant rate over 120 minutes, maintaining the temperature at 0-5°C. After the addition was complete, the temperature was maintained at 5°C for 10 hours. 121.81 g of resorcinol was added to the one-step Friedel-Crafts reaction solution. After the addition was complete, the temperature was raised to 60°C and the reaction was maintained for 6 hours.

[0074] After the reaction, the reaction solution was transferred to a hydrolysis kettle, 1200 mL of 50% isobutanol aqueous solution was added dropwise, the temperature was controlled at 80°C, the liquid was allowed to stand and separate, the organic layer was washed with water until neutral, and then the isobutanol and water were removed by vacuum distillation at 100°C.

[0075] After distillation, the material was transferred to a decolorization kettle, where 17 g of activated carbon was added. The mixture was stirred at 110°C for 1 hour for decolorization. The decolorized solution was then hot filtered and transferred to a crystallization kettle. 1440 mL of n-heptane was then added to the crystallization kettle. The temperature was raised until the solution was clear, then cooled to 10°C at a rate of 3°C / h. Solid-liquid separation was performed, and the product was dried under vacuum at 120°C to obtain the pale yellow desired product. The yield was 82%, the purity was 95.6%, the color was 5, the transmittance was 96% (460 nm), the volatile matter was 0.04%, and the ash content was 0.02%.

[0076] Comparative Example 3:

[0077] After nitrogen displacement, 2400 mL of chlorobenzene was added to the Friedel-Crafts reactor, stirring was initiated, and 200 g of cyanuric chloride and 578.45 g of anhydrous aluminum chloride were added. After addition, stirring was continued at 5°C for 1 hour. Then, 16 g of 36% hydrochloric acid was added. Stirring was continued for 1 hour, and the temperature was controlled at 0-5°C. 119.23 g of m-xylene was added dropwise at a constant rate over 60 minutes. After the addition was complete, the temperature was maintained at 5°C for 0.5 hours. Then, 119.23 g of m-xylene was added dropwise at a constant rate over 120 minutes, maintaining the temperature at 0-5°C. After the addition was complete, the temperature was maintained at 5°C for 10 hours. 121.81 g of resorcinol was added to the one-step Friedel-Crafts reaction solution. After the addition was complete, the temperature was raised to 60°C and the reaction was continued for 6 hours.

[0078] After the reaction, the reaction solution was transferred to a hydrolysis kettle, 1200 mL of 50% isobutanol aqueous solution was added dropwise, the temperature was controlled at 80°C, the liquid was allowed to stand and separate, the organic layer was washed with water until neutral, and then the isobutanol and water were removed by vacuum distillation at 100°C.

[0079] After distillation, the material was transferred to a decolorization kettle, where 17 g of activated carbon was added. The mixture was stirred at 110°C for 1 hour for decolorization. The decolorized solution was then hot filtered and transferred to a crystallization kettle. 1440 mL of n-heptane was then added to the crystallization kettle. The temperature was raised until the solution was clear, then cooled to 10°C at a rate of 3°C / h. Solid-liquid separation was performed, and the product was dried under vacuum at 120°C to obtain the pale yellow desired product. The yield was 85.4%, the purity was 97.3%, the color was 6, the transmittance was 97% (460 nm), the volatile matter was 0.05%, and the ash content was 0.03%.

[0080] Comparative Example 4:

[0081] After nitrogen displacement, 2400 mL of chlorobenzene was added to the Friedel-Crafts reactor. Stirring was initiated, followed by the addition of 200 g of cyanuric chloride and 462.76 g of anhydrous aluminum chloride. Stirring was continued at 5°C for 1 hour. Then, 16 g of 36% hydrochloric acid was added. Stirring was continued for 1 hour. After the addition was complete, 119.23 g of m-xylene was added dropwise at a constant rate over 60 minutes. The mixture was incubated for 0.5 hours. Then, 119.23 g of m-xylene was added dropwise at a constant rate over 120 minutes. The mixture was incubated at 15°C for 10 hours. 121.81 g of resorcinol was added to the one-step Friedel-Crafts reaction mixture. After the addition was complete, the mixture was heated to 60°C and incubated for 6 hours.

[0082] After the reaction was completed, the reaction solution was transferred to a hydrolysis kettle and a hydrochloric acid aqueous solution (220 g 36% hydrochloric acid + 1330 g water) was added dropwise. The fluidity deteriorated during the addition. After the acid water was added, the temperature was controlled to 50°C and it could not be stirred normally, forming a paste-like solid mixture. The target product could not be separated after filtration or centrifugation, and the experiment failed.

[0083] Comparative Example 5:

[0084] After nitrogen displacement, 2400 mL of chlorobenzene was added to the Friedel-Crafts reactor. Stirring was initiated, followed by the addition of 200 g of cyanuric chloride and 462.76 g of anhydrous aluminum chloride. Stirring was continued at 5°C for 1 hour. Then, 16 g of 36% hydrochloric acid was added. Stirring was continued for 1 hour. After the addition was complete, 119.23 g of m-xylene was added dropwise at a constant rate over 60 minutes. The mixture was incubated for 0.5 hours. Then, 119.23 g of m-xylene was added dropwise at a constant rate over 120 minutes. The mixture was incubated at 15°C for 10 hours. 121.81 g of resorcinol was added to the one-step Friedel-Crafts reaction mixture. After the addition was complete, the mixture was heated to 60°C and incubated for 6 hours.

[0085] After the reaction, the reaction solution was added dropwise to a hydrolysis kettle containing hydrochloric acid water (440 g 36% hydrochloric acid + 2660 g water). After the addition was completed, the temperature was controlled to 50°C and normal stirring could not be performed. A paste-like solid mixture was formed, and material transfer was difficult. The target product could not be separated after filtration or centrifugation, and the experiment failed.

[0086] Comparative Example 6:

[0087] After nitrogen displacement, 2400 mL of chlorobenzene was added to the Friedel-Crafts reactor. Stirring was initiated, followed by the addition of 200 g of cyanuric chloride and 462.76 g of anhydrous aluminum chloride. Stirring was continued at 5°C for 1 hour. Then, 16 g of 36% hydrochloric acid was added. Stirring was continued for 1 hour. After the addition was complete, 119.23 g of m-xylene was added dropwise at a constant rate over 60 minutes. The mixture was incubated for 0.5 hours. Then, 119.23 g of m-xylene was added dropwise at a constant rate over 120 minutes. The mixture was incubated at 15°C for 10 hours. 121.81 g of resorcinol was added to the one-step Friedel-Crafts reaction mixture. After the addition was complete, the mixture was heated to 60°C and incubated for 6 hours.

[0088] After the reaction, the reaction solution was transferred to a hydrolysis kettle, 1200 mL of 50% isobutanol aqueous solution was added dropwise, the temperature was controlled at 80°C, the liquid was allowed to stand and separate, the organic layer was washed with water until neutral, and then the isobutanol and water were removed by vacuum distillation at 100°C.

[0089] After distillation, the material was transferred to a decolorization kettle, where 17 g of activated carbon was added. The mixture was stirred at 110°C for 1 hour for decolorization. The decolorized solution was then hot filtered and transferred to a crystallization kettle. The temperature was raised until the solution was clear, then cooled to 10°C at a rate of 3°C / h. Solid-liquid separation was performed, and vacuum drying at 120°C afforded the pale yellow desired product. The yield was 87.2%, the purity was 97.16%, the color was 8, the transmittance was 96.3% (460 nm), the volatile matter was 0.06%, and the ash content was 0.02%.

[0090] Comparative Example 7:

[0091] After nitrogen displacement, 2400 mL of chlorobenzene was added to the Friedel-Crafts reactor. Stirring was initiated, followed by the addition of 200 g of cyanuric chloride and 462.76 g of anhydrous aluminum chloride. Stirring was continued at 5°C for 1 hour. Then, 16 g of 36% hydrochloric acid was added. Stirring was continued for 1 hour. After the addition was complete, 119.23 g of m-xylene was added dropwise at a constant rate over 60 minutes. The mixture was incubated for 0.5 hours. Then, 119.23 g of m-xylene was added dropwise at a constant rate over 120 minutes. The mixture was incubated at 15°C for 10 hours. 121.81 g of resorcinol was added to the one-step Friedel-Crafts reaction mixture. After the addition was complete, the mixture was heated to 60°C and incubated for 6 hours.

[0092] After the reaction, the reaction solution was transferred to a hydrolysis kettle, 1200 mL of 50% isopropyl alcohol aqueous solution was added dropwise, the temperature was controlled at 80°C, the liquid was allowed to stand and separate, the organic layer was washed with water until neutral, and then the isopropyl alcohol and water were removed by vacuum distillation at 100°C.

[0093] After distillation, the material was transferred to a decolorization kettle, where 17 g of activated carbon was added. The mixture was stirred and decolorized at 110°C for 1 hour. The decolorized solution was then hot filtered and transferred to a crystallization kettle. The solvent, chlorobenzene, was evaporated under reduced pressure. 1500 mL of isopropanol was then added to the crystallization kettle. The temperature was raised until the solution was clear, then cooled to 10°C at a rate of 3°C / h. Solid-liquid separation was performed, and the product was vacuum-dried at 120°C to obtain the pale yellow desired product. The yield was 53%, the purity was 98.3%, the color was 5, the transmittance was 97% (460 nm), the volatile matter was 0.02%, and the ash content was 0.02%.

[0094] Comparative Example 8:

[0095] After nitrogen displacement, 2400 mL of chlorobenzene was added to the Friedel-Crafts reactor. Stirring was initiated, followed by the addition of 200 g of cyanuric chloride and 462.76 g of anhydrous aluminum chloride. Stirring was continued at 5°C for 1 hour. Then, 16 g of 36% hydrochloric acid was added. Stirring was continued for 1 hour. After the addition was complete, 119.23 g of m-xylene was added dropwise at a constant rate over 60 minutes. The mixture was incubated for 0.5 hours. Then, 119.23 g of m-xylene was added dropwise at a constant rate over 120 minutes. The mixture was incubated at 15°C for 10 hours. 121.81 g of resorcinol was added to the one-step Friedel-Crafts reaction mixture. After the addition was complete, the mixture was heated to 60°C and incubated for 6 hours.

[0096] After the reaction, the reaction solution was transferred to a hydrolysis kettle, 1200 mL of 50% isopropyl alcohol aqueous solution was added dropwise, the temperature was controlled at 80°C, the liquid was allowed to stand and separate, the organic layer was washed with water until neutral, and then the isopropyl alcohol and water were removed by vacuum distillation at 100°C.

[0097] After distillation, the material was transferred to a decolorization kettle, where 17 g of activated carbon was added. The mixture was stirred at 110°C for 1 hour for decolorization. The decolorized solution was then hot filtered and transferred to a crystallization kettle. 1440 mL of isopropanol was then added to the crystallization kettle. The temperature was raised until the solution was clear, then cooled to 10°C at a rate of 3°C / h. Solid-liquid separation was performed, and the product was dried under vacuum at 120°C to obtain the pale yellow desired product. The yield was 67%, the purity was 97.66%, the color was 7, the transmittance was 96% (460 nm), the volatile matter was 0.04%, and the ash content was 0.02%.

[0098] Comparative Example 9:

[0099] After nitrogen displacement, 3000 mL of chlorobenzene was added to the Friedel-Crafts reactor. Stirring was initiated, followed by the addition of 200 g of cyanuric chloride and 462.76 g of anhydrous aluminum chloride. Stirring was continued at 5°C for 1 hour. Then, 16 g of 36% hydrochloric acid was added, followed by stirring for 1 hour. After this addition, 119.23 g of m-xylene was added dropwise at a constant rate over 60 minutes. The mixture was incubated for 0.5 hours. Then, 119.23 g of m-xylene was added dropwise at a constant rate over 120 minutes. The mixture was incubated at 15°C for 10 hours. 121.81 g of resorcinol was added to the one-step Friedel-Crafts reaction mixture. After this addition, the mixture was heated to 60°C and incubated for 6 hours.

[0100] After the reaction, the reaction solution was transferred to a hydrolysis kettle, 1200 mL of 50% isopropyl alcohol aqueous solution was added dropwise, the temperature was controlled at 80°C, the liquid was allowed to stand and separate, the organic layer was washed with water until neutral, and then the isopropyl alcohol and water were removed by vacuum distillation at 100°C.

[0101] After distillation, the material was transferred to a decolorization kettle, where 17 g of activated carbon was added. The mixture was stirred at 110°C for 1 hour for decolorization. The decolorized solution was then hot filtered and transferred to a crystallization kettle. 720 mL of n-heptane was then added to the crystallization kettle. The temperature was raised until the solution was clear, then cooled to 10°C at a rate of 3°C / h. Solid-liquid separation was performed, and the product was dried under vacuum at 120°C to obtain the pale yellow desired product. The yield was 86.3%, the purity was 97.6%, the color was 7, the transmittance was 97% (460 nm), the volatile matter was 0.05%, and the ash content was 0.02%.

[0102] Comparative Example 10:

[0103] After nitrogen displacement, 2400 mL of chlorobenzene was added to the Friedel-Crafts reactor. Stirring was initiated, followed by the addition of 200 g of cyanuric chloride and 462.76 g of anhydrous aluminum chloride. Stirring was continued at 5°C for 1 hour. Then, 16 g of 36% hydrochloric acid was added. Stirring was continued for 1 hour. After the addition was complete, 119.23 g of m-xylene was added dropwise at a constant rate over 60 minutes. The mixture was incubated for 0.5 hours. Then, 119.23 g of m-xylene was added dropwise at a constant rate over 120 minutes. The mixture was incubated at 15°C for 10 hours. 121.81 g of resorcinol was added to the one-step Friedel-Crafts reaction mixture. After the addition was complete, the mixture was heated to 60°C and incubated for 6 hours.

[0104] After the reaction, the reaction solution was transferred to a hydrolysis kettle, 1200 mL of 50% isobutanol aqueous solution was added dropwise, the temperature was controlled at 80°C, the liquid was allowed to stand and separate, the organic layer was washed with water until neutral, and then the isobutanol and water were removed by vacuum distillation at 100°C.

[0105] After distillation, the material was transferred to a crystallizer, to which 1440 mL of n-heptane was added. The temperature was raised until the solution became clear, then cooled to 10°C at a rate of 3°C / h. Solid-liquid separation was performed, and vacuum drying at 120°C afforded the pale yellow desired product. The yield was 92.5%, the purity was 99%, the color was 10, the transmittance was 61.3% (460 nm), the volatile matter was 0.05%, and the ash content was 0.02%.

[0106] It should be noted that the above content merely illustrates the technical idea of ​​the present invention and cannot be used to limit the scope of protection of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for synthesizing 4,6-bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine, characterized in that: The following steps are involved: (1) One-step Friedel-Crafts reaction: under nitrogen protection, solvent 1, cyanuric chloride and anhydrous alumina are added to a Friedel-Crafts reactor, stirred at 0-30°C for 0.5-2h, then 36% hydrochloric acid solution is added, and the reaction is continued for 0.5-1h. Meta-xylene is added dropwise twice, and the reaction is continued for 6-12h after the addition is completed, with an interval of 0.5-1h between the two additions; (2) Two-step Friedel-Crafts reaction, adding resorcinol to the reaction solution of the one-step Friedel-Crafts reaction, and then heating to 50-80°C and keeping the temperature for 4-8 hours; (3) washing with water. After the two-step Friedel-Crafts reaction is completed, an aqueous solution of alcohol is added dropwise to the reaction solution or the reaction solution is dropped into an aqueous solution of alcohol. After standing for separation, the reaction solution is washed with water until it is neutral. The reaction solution after washing with water is distilled under negative pressure at 100-110° C. with a vacuum degree of ≤10 kPa to remove alcohol and water. (4) Decolorization and crystallization. A decolorizing agent is added to the reaction solution obtained in step (3) and the reaction solution is kept warm for decolorization. After the decolorizing agent is removed by hot filtration, solvent 2 is added. The reaction solution is heated to a temperature of 10-20° C. for solid-liquid separation and vacuum dried to obtain the target product 4,6-di(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine.

2. The method for synthesizing 4,6-bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine according to claim 1, characterized in that: In step (1), the solvent 1 is chlorobenzene or o-dichlorobenzene, the mass volume ratio of cyanuric chloride to solvent 1 is 1:10-15; and the molar ratio of anhydrous aluminum chloride to cyanuric chloride is 3-3.5:

1.

3. The method for synthesizing 4,6-bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine according to claim 1, characterized in that: The mass ratio of hydrochloric acid solution to cyanuric chloride is 0.05-0.10:1, and the molar ratio of meta-xylene to cyanuric chloride is 1.95-2.05:

1.

4. The method for synthesizing 4,6-bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine according to claim 1, characterized in that: In step (1), the time for adding m-xylene is 3-5 hours, and the temperature for adding and the temperature for keeping the reaction are 10-30°C.

5. The method for synthesizing 4,6-bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine according to claim 1, characterized in that: In step (2), the molar ratio of resorcinol to cyanuric chloride in step (1) is 1-1.05:

1.

6. The method for synthesizing 4,6-bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine according to claim 1, characterized in that: In step (3), the mass volume ratio of cyanuric chloride to alcohol aqueous solution in step (1) is 1:5-10.

7. The method for synthesizing 4,6-bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine according to claim 1, characterized in that: In step (3), the volume proportion of alcohol in the alcohol aqueous solution is 50-60%, the alcohol is isopropanol or isobutanol, and the water washing temperature is 70-80°C.

8. The method for synthesizing 4,6-bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine according to claim 1, characterized in that: In step (4), the decolorizing agent is one of activated clay and activated carbon or a combination thereof, the amount of the decolorizing agent is 3-10% of the weight of the theoretically generated target product, the decolorizing temperature is 110-120° C., and the decolorizing time is 1-2 h.

9. The method for synthesizing 4,6-bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine according to claim 1, characterized in that: In step (4), solvent 2 is n-heptane or cyclohexane, and the volume ratio of solvent 2 to solvent 1 in step (1) is 0.5-1:

1.

10. The method for synthesizing 4,6-bis(2,4-dimethylphenyl)-2-(2,4-dihydroxyphenyl)-1,3,5-triazine according to claim 1, characterized in that: In step (4), the temperature is raised to 95-105°C to dissolve, then cooled to 10-20°C at a cooling rate of 3-8°C / h for solid-liquid separation, and vacuum dried at 100-120°C at a vacuum degree of ≤10 kPa.

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