Preparation method of 2,4-bis(biphenyl-4-yl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine

Abstract

The present invention discloses a method for preparing 2,4-bis(biphenyl-4-yl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine. The preparation method comprises: (1) using cyanuric chloride and m-diphenol as reaction raw materials, performing a first Friedel-Crafts reaction under the promotion of a highly selective perfluorosulfonate catalyst to obtain a monosubstituted product 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine; (2) under the action of aluminum chloride, subjecting 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine to a second Friedel-Crafts reaction with biphenyl. The preparation method provided by the present invention has cheap and readily available raw materials, few reaction steps, few unit reactions, feasible operation, high product purity and yield, convenient separation and purification of intermediates, low perfluorosulfonate catalyst consumption and recyclability, reducing the three wastes, easy-to-control process conditions, and has a prospect for industrial promotion and application.

Description

Technical Field

[0001] The present invention relates to a preparation method of key intermediates of ultraviolet absorbers UV-1600 and UV-479, in particular to a preparation method of 2,4-di(biphenyl-4-yl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine, belonging to the field of preparation of key intermediates of ultraviolet absorbers UV-1600 and UV-479. Background Art

[0002] 2,4,6-Triaryl 1,3,5-triazine UV absorbers are widely used as light stabilizers for various polyesters and other plastics due to their excellent compatibility with various polymer substrates, transparency, color, and low volatility. Compared to triazine UV absorbers with simple aryl substitutions such as UV-1164, UV-400, UV-405, and UV-1577, UV absorbers with bisphenyl units such as UV-1600 and UV-479 exhibit higher UV absorption efficiency, thus providing longer-lasting protection at lower addition levels. As light-protective agents for highly transparent polycarbonate sheets, they are particularly suitable for applications requiring ultra-durability in buildings, photovoltaic panels, window films, and display backing films. 2,4,6-Triaryl 1,3,5-triazine UV absorbers share a similar core skeleton structure and synthesis technology. The current mainstream production process uses cyanuric chloride as raw material, which undergoes a Friedel-Crafts reaction with aromatic hydrocarbons in the presence of aluminum chloride to produce 2,4-di(aryl)-6-chloro-1,3,5-triazine. After separation and purification, it undergoes a Friedel-Crafts reaction with m-diphenol to form the basic skeleton 2,4-di(aryl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine. The reaction route is as follows:

[0003]

[0004] It can be seen that for the production processes of different products of this type of UV absorber, the synthesis of 2,4-di(aryl)-6-chloro-1,3,5-triazine is the key, and the subsequent synthesis techniques are basically similar. Since benzene or m-xylene is used as both a solvent and a reaction substrate, the above-mentioned production processes are effective for 2,4-di(aryl)-6-chloro-1,3,5-triazines substituted with simple aromatic groups such as phenyl and 2,4-dimethylphenyl using benzene and m-xylene as raw materials. However, for biaryl-containing intermediates such as UV-1600 and UV-479, 2,4-di(biphenyl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine, since biphenyl is a solid and cannot be used as a solvent, the above-mentioned process technology is less effective, resulting in poor quality and high production costs of related products such as UV-1600 and UV-479. The reaction routes are shown below:

[0005]

[0006] The main reason for this problem is that benzene and m-xylene act as both solvents and reactants in the Friedel-Crafts reaction with cyanuric chloride. The reaction conditions are relatively mild, the selectivity is high, and the product 2,4-di(aryl)-6-chloro-1,3,5-triazine is highly crystalline and easy to purify. However, biphenyl has a high melting point and cannot serve as a solvent for the Friedel-Crafts reaction on its own, necessitating the use of an additional solvent. Furthermore, biphenyl has low reactivity and a weak localization effect, resulting in the production of isomers, tandem products, and triaryl products. These inevitably affect subsequent reactions and the quality of the final UV-1600 and UV-479 products, or require cumbersome post-processing and separation and purification operations, increasing production costs. Therefore, although UV-1600 and UV-479 perform better, their current high production costs and high market prices limit their widespread application.

[0007] To address the quality issues of UV-1600 and UV-479, the technical solutions currently reported in public literature mainly focus on developing highly selective 2,4-di(biphenyl-4-yl)-6-chloro-1,3,5-triazine synthesis technologies, which are mainly classified into three categories: 1) improving the Friedel-Crafts reaction of biphenyl to reduce isomers and triaryl-substituted impurities; 2) introducing biphenyl units by reacting tricyanuric chloride raw materials with biphenyl metal organic reagents to completely eliminate isomers; and 2) using biphenyl carboxylic acid derivatives as raw materials to construct triazine structures through cyclization reactions to completely eliminate isomers and triaryl-substituted impurities.

[0008] Chinese patent CN110372620A discloses a method for synthesizing 2,4-di(biphenyl-4-yl)-6-chloro-1,3,5-triazine by reacting cyanuric chloride with biphenyl in a Friedel-Crafts reaction improved by introducing dry hydrogen chloride as a co-catalyst. The target product can be obtained in moderate to good yields, but the reaction still produces approximately 5% of 2,4,6-tris(biphenyl-4-yl)-1,3,5-triazine, and the isomerization is not described.

[0009] International patent WO2020144094A1 discloses a route, and its reaction route is as follows:

[0010]

[0011] It first converts a chlorine group in cyanuric chloride into an amino group that is inert in the Friedel-Crafts reaction, namely 2,4-dichloro-6-amino-1,3,5-triazine, which then reacts with biphenyl. The amino group is then hydrolyzed and chlorinated to form 2,4-di(biphenyl-4-yl)-6-chloro-1,3,5-triazine. Although this route eliminates the trisubstituted impurity 2,4,6-tris(biphenyl-4-yl)-1,3,5-triazine, it has three more steps: aminolysis, hydrolysis, and chlorination, resulting in four production units instead of one. Its practical application value is not high.

[0012] Chinese patent CN113149918A partially improves the route disclosed in international patent WO2020144094A1 by reducing the amino-to-hydroxyl unit. Specifically, cyanuric chloride is first reacted with acetic acid and then directly hydrolyzed to obtain an intermediate in which a chlorine group is converted to a hydroxyl group, namely 2,4-dichloro-6-hydroxy-1,3,5-triazine. This is then reacted with biphenyl in a Friedel-Crafts reaction to convert the hydroxyl group to chlorine. However, the cost of preparing 2,4-dichloro-6-hydroxy-1,3,5-triazine is higher than that of the corresponding amino intermediate.

[0013] Chinese patent CN112028846A makes further improvements. First, cyanuric chloride reacts with amide to form a salt, and then reacts with biphenyl in a Friedel-Crafts reaction to obtain 2,4-di(biphenyl-4-yl)-6-hydroxy-1,3,5-triazine. The hydroxyl group is then converted into chlorine. The reaction scheme is shown below:

[0014]

[0015] This preparation reaction has the problems of requiring low temperature for the salt formation reaction and poor thermal stability of the salt intermediate.

[0016] Chinese patent CN102782033A and international patent WO 2011067282 disclose a method for obtaining 2,4-di(biphenyl-4-yl)-6-chloro-1,3,5-triazine by reacting cyanuric chloride as a raw material with a 4-biphenyl Grignard reagent. The reaction scheme is as follows:

[0017]

[0018] The raw material 4-halobiphenyl in this reaction is expensive. The preparation of biphenyl Grignard reagent and the subsequent reaction with cyanuric chloride require anhydrous and oxygen-free operations. The reaction conditions are relatively harsh, and the water content of the solvent and equipment is required to be high, resulting in high industrial production costs.

[0019] Chinese patent CN108713015A and Korean patent KR2016132724 disclose a method for obtaining 2,4-di(biphenyl-4-yl)-6-chloro-1,3,5-triazine by a Suzuki coupling reaction using cyanuric chloride as a raw material and biphenyl-4-boronic acid (ester) in the presence of a palladium catalyst. While this method avoids the use of Grignard reagents and simplifies the process, the high cost of biphenyl-4-boronic acid (ester) and the palladium catalyst make industrial production unfeasible.

[0020] Chinese patents CN113234032A and CN113087678A respectively disclose a method of condensing and cyclizing biphenyl-4-carbonitrile and urea in the presence of a strong base, sodium hydride or sodium amide, to form 2,4-di(biphenyl-4-yl)-6-hydroxy-1,3,5-triazine, and then chlorinating to obtain 2,4-di(biphenyl-4-yl)-6-chloro-1,3,5-triazine. The reaction scheme is as follows:

[0021]

[0022] The above reaction route is relatively short, but biphenyl-4-carbonitrile is expensive, and the strong bases sodium hydride and sodium amide are sensitive to water and require anhydrous operation, which is somewhat dangerous.

[0023] As can be seen from the above, the synthesis methods of 2,4-di(biphenyl-4-yl)-6-chloro-1,3,5-triazine currently reported in the public literature have one or more of the following problems, which lead to high production costs and even make it difficult to achieve industrial scale-up production, including: insufficient reaction selectivity, which produces impurities that are difficult to remove, and requires a tedious separation and purification process to improve the purity of the target intermediate product; the need to adopt a multi-step reaction and a long route; the cost of raw materials is high, and expensive catalysts and reagents are used; the control of the reaction process conditions is demanding, and industrial scale-up technology has many difficulties.

[0024] For the production of UV-1600 and UV-479, the purpose of preparing 2,4-bis(biphenyl-4-yl)-6-chloro-1,3,5-triazine is to react with m-diphenol to synthesize 2,4-bis(biphenyl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine. The reaction route is as follows:

[0025]

[0026] However, due to the technical difficulties in preparing the key intermediate 2,4-di(biphenyl-4-yl)-6-chloro-1,3,5-triazine, the above reaction route leads to the difficulty and high cost of producing UV-1600 and UV-479, and there is currently no effective solution.

[0027] European Patent EP0941989A3 discloses a route of attempting to replace the chlorine group in cyanuric chloride with a phenoloxy group, followed by a Friedel-Crafts reaction with an aromatic hydrocarbon such as m-xylene, followed by an acid-catalyzed rearrangement (phenol is m-diphenol) or a Friedel-Crafts reaction with m-diphenol to obtain 2,4-di(aryl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine. The reaction route is shown below:

[0028]

[0029] Although the technical route of the above-mentioned reaction avoids the intermediate 2,4-di(aryl)-6-chloro-1,3,5-triazine, unfortunately, even for the UV-1164 intermediate 2,4-di(2,4-dimethylphenyl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine with lower technical difficulty, both the one-pot method and the step-by-step method have problems such as low yield, many by-products, complex composition of the crude product, and difficulty in purifying the target product, judging from the experimental results disclosed in the patent, and have no practical application value and need to be improved. Summary of the Invention

[0030] After extensive and in-depth research, the inventors have obtained a new preparation method for 2,4-di(biphenyl-4-yl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine, a key intermediate for synthesizing UV-1600 and UV-479, through route design, catalyst screening and reaction condition optimization. The preparation method has the advantages of fewer unit reactions, feasible operation, high product purity and yield, and good industrialization prospects.

[0031] Therefore, the present invention provides a method for preparing 2,4-bis(biphenyl-4-yl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine, comprising:

[0032] (1) Using cyanuric chloride and m-diphenol as the reaction raw materials, a first Friedel-Crafts reaction was carried out under the promotion of a highly selective perfluorosulfonate catalyst to selectively obtain the monosubstituted product 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine;

[0033] (2) Under the action of aluminum chloride, the reaction product of step (1), 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine, is subjected to a second Friedel-Crafts reaction with biphenyl to obtain 2,4-di(biphenyl-4-yl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine.

[0034] As a preferred embodiment of the present invention, the highly selective perfluorosulfonate catalyst is selected from any one of trifluoromethanesulfonic acid, perfluorosulfonic acid or bis(trifluoromethanesulfonyl)imide metal salts; further, the perfluorosulfonic acid is a C1-C4 perfluoroalkylsulfonic acid, preferably trifluoromethanesulfonic acid or perfluorobutylsulfonic acid; the bis(trifluoromethanesulfonyl)imide metal salt is preferably bis(trifluoromethanesulfonyl)imide aluminum, lithium, zinc, copper, iron or rare earth metal salt, preferably bis(trifluoromethanesulfonyl)imide aluminum, lanthanum or yttrium salt, and most preferably bis(trifluoromethanesulfonyl)imide aluminum salt.

[0035] Most preferably, the highly selective perfluorosulfonate catalyst is selected from any one of aluminum trifluoromethanesulfonate, aluminum perfluorobutanesulfonate, zinc perfluorobutanesulfonate, aluminum bistrifluoromethanesulfonyl imide, zinc bistrifluoromethanesulfonyl imide, lithium bistrifluoromethanesulfonyl imide, zinc trifluoromethanesulfonate, lanthanum trifluoromethanesulfonate, neodymium trifluoromethanesulfonate, yttrium trifluoromethanesulfonate, iron trifluoromethanesulfonate or copper trifluoromethanesulfonate.

[0036] As a preferred embodiment of the present invention, the conditions for the first Friedel-Crafts reaction in step (1) include: equal molar amounts of cyanuric chloride and m-diphenol, catalyzed by a highly selective perfluorosulfonate catalyst, in the presence of an organic solvent, and carrying out a Friedel-Crafts reaction at a reaction temperature of 100-140° C. to selectively obtain the monosubstituted product 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine; wherein the organic solvent is selected from any one of toluene, xylene, or chlorobenzene, or a mixture of more than one organic solvent in any proportion.

[0037] As a preferred embodiment of the present invention, the time of the first Friedel-Crafts reaction in step (1) is preferably 5-10 hours.

[0038] As a preferred embodiment of the present invention, after the first Friedel-Crafts reaction in step (1) is completed, the highly selective perfluorosulfonic acid metal salt catalyst is washed with water, recovered, dried and reused.

[0039] As a preferred specific embodiment of the present invention, in step (2), 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine is reacted with 2-4 times the amount of biphenyl in a dichlorobenzene solvent under the catalysis of 2-3 times the amount of aluminum chloride to undergo a second Friedel-Crafts reaction to obtain 2,4-di(biphenyl-4-yl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine; wherein the temperature of the second Friedel-Crafts reaction is preferably 120°C-130°C.

[0040] Compared with the prior art, the preparation method of 2,4-bis(biphenyl-4-yl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine of the present invention has the following advantages: cheap and readily available raw materials, fewer reaction steps, convenient separation and purification of intermediates, small amount of perfluorosulfonate catalyst used and the ability to be recycled and reused, reducing the three wastes, and easy control of process conditions and industrial scale-up. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The present invention provides a reaction route for 2,4-bis(biphenyl-4-yl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine. DETAILED DESCRIPTION

[0042] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer as the description proceeds. However, these embodiments are merely exemplary and do not limit the scope of the present invention in any way. It should be understood by those skilled in the art that the details and forms of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, and such modifications and replacements fall within the scope of protection of the present invention.

[0043] Preparatory Example 1 Preparation of 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine

[0044] To a 1-liter three-necked flask equipped with a mechanical stirrer and a thermometer, 500 mL of toluene, 184 g of cyanuric chloride, and 110 g of m-diphenol (1 mol) were added and stirred until uniformly dispersed. Aluminum trifluoromethanesulfonate (14 g, 0.03 mol) was then added and the temperature was raised to 100°C for 10 h. The reaction mixture was cooled to room temperature to obtain a suspension. Water was added for stirring and slurrying, and the suspension was filtered. The filter cake was rinsed with water and the filtrate was evaporated to dryness to recover 13.8 g of toluene and aluminum trifluoromethanesulfonate catalyst (97% recovery). The filter cake was slurried with methanol, filtered, and dried to obtain 219 g of a light beige solid (85% yield).

[0045] Preparatory Example 2 Preparation of 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine

[0046] To a 1-liter three-necked flask equipped with a mechanical stirrer and a thermometer, add 500 mL of chlorobenzene, 184 g of cyanuric chloride, and 110 g of m-diphenol (1 mol). Stir and disperse until uniformly dispersed. Then add aluminum trifluoromethanesulfonate (4.75 g, 0.01 mol). Heat to 140°C and react for 8 hours. Cool the reaction mixture to room temperature to obtain a suspension. Add water, stir, and slurry. Filter the suspension, rinse the filter cake with water, and evaporate the filtrate to dryness to recover 4.50 g of chlorobenzene and aluminum trifluoromethanesulfonate catalyst (95% recovery). Slurry the filter cake with methanol, filter, and dry to obtain 196 g of a light beige solid (76% yield).

[0047] Preparatory Example 3 Preparation of 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine

[0048] To a 1-liter three-necked flask equipped with a mechanical stirrer and a thermometer, add 500 mL of xylene, 184 g of cyanuric chloride, and 110 g of m-diphenol (1 mol). Stir and disperse until uniformly dispersed. Then, add aluminum trifluoromethanesulfonate (4.75 g, 0.01 mol). Heat to 135°C and react for 10 hours. Cool the reaction mixture to room temperature to obtain a suspension. Add water, stir, and slurry. Filter the suspension, rinse the filter cake with water, and evaporate the filtrate to dryness to recover 4.51 g of xylene and aluminum trifluoromethanesulfonate catalyst (95% recovery). Slurry the filter cake with methanol, filter, and dry to obtain 188 g of a light beige solid (73% yield).

[0049] Preparatory Example 4 Preparation of 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine

[0050] To a 1-liter three-necked flask equipped with a mechanical stirrer and a thermometer, add 500 mL of chlorobenzene, 184 g of cyanuric chloride, and 110 g of m-diphenol (1 mol). Stir and disperse until uniformly dispersed. Then, add aluminum trifluoromethanesulfonate (14 g, 0.03 mol). Heat to 140°C and react for 5 h. Cool the reaction mixture to room temperature to obtain a suspension. Add water, stir, and slurry. Filter the suspension, rinse the filter cake with water, and evaporate the filtrate to dryness to recover 13.5 g of chlorobenzene and aluminum trifluoromethanesulfonate catalyst (96% recovery). Slurry the filter cake with methanol, filter, and dry to obtain 232 g of a light beige solid (90% yield).

[0051] Preparatory Example 5-16 Preparation of 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine

[0052] The operation was the same as in Preparative Example 4, except that the type of perfluorosulfonate catalyst was different. The results are listed in Table 1.

[0053] To a 1-liter three-necked flask equipped with a mechanical stirrer and a thermometer, add 500 mL of chlorobenzene, 184 g of cyanuric chloride (1 mol), and 110 g of m-diphenol (1 mol). Stir and disperse until uniform, then add the catalyst. Heat to 140°C and allow to react for 5-10 hours. Cool the reaction mixture to room temperature to obtain a suspension, add water, stir, and slurry. Filter the suspension, rinse the filter cake with water, and evaporate the filtrate to dryness to recover the chlorobenzene and catalyst. Slurry the filter cake with methanol to remove unreacted starting materials, filter, and dry to obtain the product, 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine.

[0054] Table 1 Experimental results of preliminary examples 5-16

[0055]

[0056] Example 1 Preparation of 2,4-bis(biphenyl-4-yl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine

[0057] To a 1000mL four-necked flask equipped with a mechanical stirrer, thermometer, and gas inlet / outlet, add 500mL of dichlorobenzene. Under nitrogen, add 129g (0.5mol) of 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine, 134g (1mol) of aluminum trichloride, and 154g (1mol) of biphenyl in that order. Stirring was initiated, the reaction was heated to 130°C until no gas evolution occurred. Cool to room temperature to obtain a dark red viscous solution. The reaction solution was poured into 100ml of 3wt% dilute hydrochloric acid. The organic layer was separated and the majority of the chlorobenzene was recovered by vacuum distillation. The filter cake was then purified by recrystallization from toluene to obtain 173g of the desired product as a yellow powder in a 70% yield. 1 HNMR(400MHz,DMSO-d6)δ(ppm):13.3(br,s,1H),10.5(br,s,1H),8.61(d,J=8.3Hz,4H),8.50(d,J=8.6Hz,1H),7.90(d ,J=8.3Hz,4H),7.80(d,J=7.4Hz,4H),7.50(t,J=7.4Hz,4H),7.45(t,J=7.2Hz,2H),6.55(d,J=8.6Hz,1H),6.39(s,1H).

[0058] Example 2 Preparation of 2,4-bis(biphenyl-4-yl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine

[0059] To a 1000mL four-necked flask equipped with a mechanical stirrer, thermometer, and gas inlet / outlet, add 500mL of dichlorobenzene. Under nitrogen, add 129g (0.5mol) of 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine, 166g (1.25mol) of aluminum trichloride, and 192g (1.25mol) of biphenyl in that order. Stirring was initiated, the reaction was heated to 130°C until no gas evolution occurred. Cool to room temperature to yield a dark red viscous solution. The reaction solution was poured into 100ml of 3wt% dilute hydrochloric acid. The organic layer was separated and the majority of the chlorobenzene was recovered by vacuum distillation. Filtered with suction, the filter cake was purified by recrystallization from toluene to yield 203g of a yellow powder, with a yield of 82%. 1HNMR(400MHz,DMSO-d6)δ(ppm):13.3(br,s,1H),10.5(br,s,1H),8.61(d,J=8.3Hz,4H),8.50(d,J=8.6Hz,1H),7.90(d ,J=8.3Hz,4H),7.80(d,J=7.4Hz,4H),7.50(t,J=7.4Hz,4H),7.45(t,J=7.2Hz,2H),6.55(d,J=8.6Hz,1H),6.39(s,1H).

[0060] Example 3 Preparation of 2,4-bis(biphenyl-4-yl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine

[0061] To a 1000mL four-necked flask equipped with a mechanical stirrer, thermometer, and gas inlet / outlet, add 500mL of dichlorobenzene. Under nitrogen, add 129g (0.5mol) of 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine, 166g (1.25mol) of aluminum trichloride, and 231g (1.5mol) of biphenyl in that order. Stirring was initiated, the reaction was heated to 130°C until no gas evolution occurred. Cool to room temperature to yield a dark red viscous solution. The reaction solution was poured into 100ml of 3wt% dilute hydrochloric acid. The organic layer was separated and the majority of the chlorobenzene was recovered by vacuum distillation. Filter the mixture with suction, and the filter cake was purified by recrystallization from toluene to yield 219g of a yellow powder, with a yield of 89%. 1 HNMR(400MHz,DMSO-d6)δ(ppm):13.3(br,s,1H),10.5(br,s,1H),8.61(d,J=8.3Hz,4H),8.50(d,J=8.6Hz,1H),7.90(d ,J=8.3Hz,4H),7.80(d,J=7.4Hz,4H),7.50(t,J=7.4Hz,4H),7.45(t,J=7.2Hz,2H),6.55(d,J=8.6Hz,1H),6.39(s,1H).

[0062] Example 4 Preparation of 2,4-bis(biphenyl-4-yl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine

[0063] To a 1000mL four-necked flask equipped with a mechanical stirrer, thermometer, and gas inlet / outlet, add 500mL of dichlorobenzene. Under nitrogen, add 129g (0.5mol) of 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine, 200g (1.5mol) of aluminum trichloride, and 308g (2mol) of biphenyl in that order. Stirring was initiated, the reaction was heated to 130°C until no gas evolution occurred. Cool to room temperature to yield a dark red viscous solution. The reaction solution was poured into 100ml of 3wt% dilute hydrochloric acid. The organic layer was separated and the majority of the chlorobenzene was recovered by vacuum distillation. Filter the mixture with suction, and the filter cake was purified by recrystallization from toluene to yield 200g of a yellow powder, with a yield of 81%. 1 HNMR(400MHz,DMSO-d6)δ(ppm):13.3(br,s,1H),10.5(br,s,1H),8.61(d,J=8.3Hz,4H),8.50(d,J=8.6Hz,1H),7.90(d ,J=8.3Hz,4H),7.80(d,J=7.4Hz,4H),7.50(t,J=7.4Hz,4H),7.45(t,J=7.2Hz,2H),6.55(d,J=8.6Hz,1H),6.39(s,1H).

[0064] Example 5 Preparation of 2,4-bis(biphenyl-4-yl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine

[0065] To a 1000mL four-necked flask equipped with a mechanical stirrer, thermometer, and gas inlet / outlet, add 500mL of dichlorobenzene. Under nitrogen, add 129g (0.5mol) of 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine, 146g (1.1mol) of aluminum trichloride, and 308g (2mol) of biphenyl in that order. Stirring was initiated, the reaction was heated to 130°C until no gas evolution occurred. Cool to room temperature to yield a dark red viscous solution. The reaction solution was poured into 100ml of 3wt% dilute hydrochloric acid. The organic layer was separated and the majority of the chlorobenzene was recovered by vacuum distillation. Filter the mixture with suction, and the filter cake was purified by recrystallization from toluene to yield 193g of a yellow powder, a 78% yield. 1 HNMR(400MHz,DMSO-d6)δ(ppm):13.3(br,s,1H),10.5(br,s,1H),8.61(d,J=8.3Hz,4H),8.50(d,J=8.6Hz,1H),7.90(d ,J=8.3Hz,4H),7.80(d,J=7.4Hz,4H),7.50(t,J=7.4Hz,4H),7.45(t,J=7.2Hz,2H),6.55(d,J=8.6Hz,1H),6.39(s,1H).

Claims

1. A method for preparing 2,4-bis(biphenyl-4-yl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine, characterized in that: include: (1) Using cyanuric chloride and m-diphenol as reaction raw materials, a first Friedel-Crafts reaction is carried out in the presence of a perfluorosulfonate catalyst to obtain a monosubstituted product 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine; the reaction conditions of the first Friedel-Crafts reaction include: the molar amounts of cyanuric chloride and m-diphenol are equal, and the reaction is carried out in the presence of an organic solvent at 100-140°C under the catalysis of a perfluorosulfonate catalyst. o C. A first Friedel-Crafts reaction is carried out at a reaction temperature to obtain a monosubstituted product, 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine; the organic solvent is selected from any one of toluene, xylene or chlorobenzene, or a mixture of more than one organic solvent in any proportion; (2) Under the action of aluminum chloride, the reaction product of step (1), 2,4-dichloro-6-(2,4-dihydroxyphenyl)-1,3,5-triazine, is reacted with 2-4 times the amount of biphenyl in a dichlorobenzene solvent under the catalysis of 2-3 times the amount of aluminum chloride to undergo a second Friedel-Crafts reaction to obtain 2,4-di(biphenyl-4-yl)-6-(2,4-dihydroxyphenyl)-1,3,5-triazine; the reaction temperature of the second Friedel-Crafts reaction is 120 o C-130 o C; The perfluorosulfonate catalyst is selected from any one of aluminum trifluoromethanesulfonate, aluminum perfluorobutanesulfonate, zinc perfluorobutanesulfonate, bistrifluoromethanesulfonyl imide aluminum, zinc trifluoromethanesulfonate, lanthanum trifluoromethanesulfonate, neodymium trifluoromethanesulfonate or yttrium trifluoromethanesulfonate.

2. The preparation method according to claim 1, characterized in that After the first Friedel-Crafts reaction in step (1) is completed, the perfluorosulfonic acid metal salt catalyst is washed with water, recovered, dried and reused.

3. The preparation method according to claim 1, characterized in that The reaction time of the first Friedel-Crafts reaction in step (1) is 5-10 hours.

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