A method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine

Abstract

This invention discloses a method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine, belonging to the field of ultraviolet absorber synthesis; the synthesis steps of this invention for preparing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine are as follows: (1) Under inert gas protection, biphenyl and 2-amino-4,6-dichlorotriazine are used as raw materials, and para-alkylation reaction is carried out under the first reaction conditions to obtain an intermediate mixture; (2) Intermediate A and intermediate B are separated from the intermediate mixture, and intermediate A continues to carry out the reaction in step (1); (3) Intermediate B is reacted with metal hydroxide to obtain intermediate C; (4) Intermediate C is iodinated to obtain intermediate D; (5) Intermediate D is reacted with resorcinol under the action of a second catalyst to carry out an ortho-alkylation reaction to obtain the product.

Description

Technical Field

[0001] This invention relates to the field of ultraviolet absorber synthesis, and a method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine. Background Technology

[0002] 2,4-Bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine is an organic chemical reagent with excellent ultraviolet absorption and thermal stability, widely used in polymer materials, light stabilizers, liquid crystal display materials, and organic optoelectronic functional materials. Its molecular structure contains multiple aromatic rings and hydroxyl functional groups, endowing it with good conjugation effects and hydrogen bonding capabilities, thus exhibiting significant advantages in ultraviolet shielding and free radical scavenging.

[0003] Currently, the synthesis of these triazine derivatives typically employs a nucleophilic substitution reaction pathway, starting with cyanuric chloride and proceeding with stepwise substitution reactions with 4-biphenol and 2,4-dihydroxyphenylboronic acid under alkaline conditions. However, existing synthetic methods generally suffer from the following problems: (1) poor reaction selectivity, with mono- and di-substituted byproducts easily generated during multi-step substitution, affecting the purity of the target product; (2) demanding reaction conditions, such as requiring low-temperature control and strict anhydrous operation, which limits industrial scale-up.

[0004] Furthermore, due to the strong coordination ability and acidity of the 2,4-dihydroxyphenyl unit, it is prone to oxidation or self-condensation side reactions in alkaline media, further reducing the yield and purity of the target product. Therefore, there is an urgent need to develop an efficient, controllable, and environmentally friendly synthetic process that can significantly improve the yield and purity of 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine while ensuring high regioselectivity and chemoselectivity. Summary of the Invention

[0005] The purpose of this invention is to provide a method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine, in order to solve the technical problems mentioned in the background section.

[0006] The technical solution to achieve the objective of this invention is: This invention provides a method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine, the synthetic steps of which include: (1) Under inert gas protection, biphenyl and 2-amino-4,6-dichlorotriazine were used as raw materials for para-alkylation reaction to obtain an intermediate mixture; (2) Dissolve the intermediate mixture in hot toluene until saturated, then let it stand and cool to room temperature, filter, and the solid obtained is intermediate B; concentrate the filtrate to obtain crude intermediate A, recrystallize crude intermediate A to obtain intermediate A, and continue the reaction of intermediate A in step (1). (3) React intermediate B with a metal hydroxide to obtain intermediate C; (4) Intermediate C is subjected to an iodination reaction to obtain intermediate D; (5) Intermediate D and resorcinol undergo ortho-alkylation reaction in the presence of a second catalyst to obtain the product; The specific reaction pathway is as follows: ; ; ; .

[0007] Furthermore, the catalyst for the para-alkylation reaction is nickel(II) ethylene glycol dimethyl ether, the catalyst promoter is tetrahydroxydiboron, the solvent is dimethyl sulfoxide, the base is potassium carbonate, the reaction temperature is 75~85℃, and the reaction time is 5~7h.

[0008] Further, the molar ratio of biphenyl, 2-amino-4,6-dichlorotriazine, nickel(II) ethylene glycol dimethyl ether, tetrahydroxydiboron, and potassium carbonate is (3~4):1:(0.3~0.4):(0.6~0.8):(6~8).

[0009] Furthermore, the temperature of the hot toluene is 58~62℃, and the solvent used for recrystallization is a mixture of n-hexane and ethyl acetate with a volume ratio of 9:1.

[0010] Further, the metal hydroxide includes sodium hydroxide, the molar ratio of intermediate B to metal hydroxide is 1:(3~4); the reaction temperature is 145~150℃; and the reaction time is 2.5~3.5h.

[0011] Furthermore, the iodizing agent in the iodination reaction is sodium iodide, the catalyst is cerium trichloride heptahydrate, the solvent is acetonitrile, and the reaction conditions are reflux for 19-21 hours.

[0012] Furthermore, the molar ratio of sodium iodide, cerium trichloride heptahydrate, and intermediate C is (1~1.2):(1.3~1.5):1.

[0013] Furthermore, the second catalyst is tris(2,2'-bipyridine)ruthenium dichloride.

[0014] Furthermore, the solvent for the ortho-alkylation reaction is a mixed solution of N,N-dimethylformamide and methanol in a volume ratio of 4:1; potassium carbonate and tetrabutylammonium iodide are also added during the ortho-alkylation reaction; the ortho-alkylation reaction conditions are nitrogen protection and light irradiation at room temperature, wherein the reaction time is 15-20 h and the wavelength of the light source is 450-480 nm.

[0015] Further, the molar ratio of resorcinol, intermediate D, potassium carbonate, tetrabutylammonium iodide, and the second catalyst is 0.6:(0.6~0.72):(2.5~2.9):(0.8~1.0):(0.0040~0.0050).

[0016] By adopting the above technical solution, the present invention has the following beneficial effects: (1) In the synthesis of 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine of the present invention, biphenyl and 2-amino-4,6-dichlorotriazine are first used as raw materials for para-alkylation reaction. The chlorine atom on the triazine ring acts as a good leaving group, promoting the introduction of triazine structure in the para position of biphenyl to obtain intermediate mixture, effectively controlling reaction selectivity and avoiding over-substitution or side reactions. The intermediate mixture mainly includes intermediate A and intermediate B. The above intermediate mixture is dissolved in hot toluene to saturation, and crystallization purification is carried out by utilizing the difference in solubility of different components in hot / cold toluene. After standing and cooling to room temperature, intermediate B precipitates preferentially due to its lower polarity and lower solubility. High-purity solid intermediate B can be obtained by filtration. The filtrate is mainly enriched with intermediate A, which has higher polarity and higher solubility. After concentration, Further purification by recrystallization yields pure intermediate A. Intermediate A is then reintroduced into the previous para-alkylation reaction, reacting with another molecule of biphenyl to generate intermediate B, thereby improving raw material utilization and reducing waste emissions, thus increasing product yield. Next, intermediate B reacts with a metal hydroxide to hydrolyze the amino group in intermediate B to form intermediate C containing an alcohol hydroxyl group. Then, intermediate C containing the alcohol hydroxyl group undergoes an iodination reaction to form an iodide intermediate D. Finally, intermediate D undergoes an ortho-alkylation reaction with resorcinol under the action of a second catalyst to obtain 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine. The 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine prepared by this invention has high yield and purity.

[0017] (2) The catalyst for the para-alkylation reaction of the present invention is nickel(II) ethylene glycol dimethyl ether, the catalyst promoter is tetrahydroxydiboron, the solvent is dimethyl sulfoxide, the base is potassium carbonate, the reaction temperature is 75~85℃, and the reaction time is 5~7h. Under these conditions, the chlorine on 2-amino-4,6-dichlorotriazine undergoes a highly selective electrophilic substitution reaction with biphenyl at the para position, which significantly reduces the formation of byproducts such as ortho-substitution and meta-substitution, and initially improves the yield and purity of the product.

[0018] (3) The molar ratio of biphenyl and 2-amino-4,6-dichlorotriazine in this invention is (3~4):1. The excess biphenyl not only acts as a reactant but also plays a diluting role, effectively reducing the probability of interaction between 2-amino-4,6-dichlorotriazine molecules or intermediates, thereby significantly inhibiting the formation of complex byproducts such as multiple chlorine atoms on the triazine ring being continuously substituted by different aryl groups. At the same time, the excess biphenyl helps to promote the substitution reaction to proceed in the forward direction, increasing the yield of the target intermediate B, and thus improving the yield and purity of the product.

[0019] (4) The catalyst for the ortho-alkylation reaction of the present invention is ruthenium tris(2,2'-bipyridine)dichloride. Under illumination with a light source wavelength of 450~480nm, ruthenium tris(2,2'-bipyridine)dichloride is converted to an excited state. The excited state of ruthenium tris(2,2'-bipyridine)dichloride is oxidized by intermediate D, and a tetravalent ruthenium tris(2,2'-bipyridine)dichloride and a triazine radical are generated through single electron transfer. The electron-deficient triazine radical adds to the electron-rich intermediate to obtain a triazine-containing resorcinol radical. Then, in a high-valence intermediate... Under the oxidation of tri(2,2'-bipyridine)ruthenium dichloride, the resorcinol radical containing triazine undergoes electron transfer transformation and deprotonation in the presence of potassium carbonate. This improves the selectivity of the ortho-alkylation reaction of intermediate D and resorcinol, thereby reducing byproducts and increasing the yield of 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine. Moreover, this reaction can be carried out under ambient temperature and light conditions, using clean energy as the reaction conditions, which effectively reduces energy consumption in the production process. Attached Figure Description

[0020] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein... Figure 1 The 1H NMR spectrum of 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine is shown in one embodiment. Detailed Implementation

[0021] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0024] The following embodiments are only used to illustrate the technical solutions of the present invention more clearly, and should not be used to limit the scope of protection of the present invention. Example A method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine, comprising the following synthetic steps: (1) Under inert gas protection, biphenyl and 2-amino-4,6-dichlorotriazine were used as raw materials for para-alkylation reaction to obtain an intermediate mixture; (2) Dissolve the intermediate mixture in hot toluene until saturated, then let it stand and cool to room temperature, filter, and the solid obtained is intermediate B; concentrate the filtrate to obtain crude intermediate A, recrystallize crude intermediate A to obtain intermediate A, and continue the reaction of intermediate A in step (1). (3) React intermediate B with a metal hydroxide to obtain intermediate C; (4) Intermediate C is subjected to an iodination reaction to obtain intermediate D; (5) Intermediate D and resorcinol undergo ortho-alkylation reaction under the action of a second catalyst to obtain the product.

[0025] The catalyst for the para-alkylation reaction is nickel(II) ethylene glycol dimethyl ether, the catalyst promoter is tetrahydroxydiboron, the solvent is dimethyl sulfoxide, the base is potassium carbonate, the reaction temperature is 75~85℃, and the reaction time is 5~7h.

[0026] The molar ratio of biphenyl, 2-amino-4,6-dichlorotriazine, nickel(II) ethylene glycol dimethyl ether, tetrahydroxydiboron, and potassium carbonate is (3~4):1:(0.3~0.4):(0.6~0.8):(6~8).

[0027] The temperature of the hot toluene is 58~62℃, and the solvent used for recrystallization is a mixture of n-hexane and ethyl acetate with a volume ratio of 9:1.

[0028] The metal hydroxide includes sodium hydroxide, and the molar ratio of intermediate B to the metal hydroxide is 1:(3~4); the reaction temperature is 145~150℃; and the reaction time is 2.5~3.5h.

[0029] The iodizing agent for the iodination reaction is sodium iodide, the catalyst is cerium trichloride heptahydrate, the solvent is acetonitrile, and the reaction conditions are reflux for 19-21 hours.

[0030] The molar ratio of sodium iodide, cerium trichloride heptahydrate, and intermediate C is (1~1.2):(1.3~1.5):1.

[0031] The second catalyst is tris(2,2'-bipyridine) ruthenium dichloride.

[0032] The solvent for the ortho-alkylation reaction is a mixed solution of N,N-dimethylformamide and methanol in a volume ratio of 4:1; potassium carbonate and tetrabutylammonium iodide are also added during the ortho-alkylation reaction; the ortho-alkylation reaction conditions are nitrogen protection and light irradiation at room temperature, wherein the reaction time is 15-20 h and the wavelength of the light source is 450-480 nm.

[0033] The molar ratio of resorcinol, intermediate D, potassium carbonate, tetrabutylammonium iodide, and the second catalyst is 0.6:(0.6~0.72):(2.5~2.9):(0.8~1.0):(0.0040~0.0050).

[0034] Example 1 Figure 1 The 1H NMR spectrum of 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine is shown.

[0035] A method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine, comprising the following synthetic steps: (1) Under argon protection, nickel(II) glycol dimethyl ether, tetrahydroxy diboron and potassium carbonate were mixed and dispersed evenly. Then, 130 times the mass of biphenyl was added to dimethyl sulfoxide. Next, biphenyl and 2-amino-4,6-dichlorotriazine were added and reacted at 75°C for 5 hours. After the reaction was completed, the mixture was cooled to room temperature and quenched with 500 times the mass of biphenyl in water. Then, 1500 times the mass of biphenyl in ethyl acetate was added and the mixture was repeatedly extracted 3 times. The organic phase was collected and washed 3 times with 1500 times the mass of biphenyl in saturated brine. Then, anhydrous sodium sulfate was added for drying, filtration, and vacuum concentration to obtain an intermediate mixture. The molar ratio of biphenyl, 2-amino-4,6-dichlorotriazine, nickel(II) glycol dimethyl ether, tetrahydroxy diboron and potassium carbonate was 3:1:0.3:0.6:6. (2) Dissolve the intermediate mixture in hot toluene at 58°C until saturated, then let it stand and cool to room temperature, filter, and the solid obtained is intermediate B; concentrate the filtrate to obtain crude intermediate A and recrystallize it with a mixture of n-hexane and ethyl acetate at a volume ratio of 9:1 to obtain intermediate A, and put intermediate A into the reaction vessel of step (1) to continue the para-alkylation reaction. (3) Mix intermediate B with 5 times its mass of 2-butoxyethanol and heat to 145°C. Add sodium hydroxide and continue stirring and mixing. Keep the mixture warm for 2.5 h. After the reaction is complete, cool to 80°C and quench with water. Add hydrochloric acid to adjust the pH to between 1 and 2. Then separate the organic layer, separate the product, wash with methanol and vacuum dry to obtain intermediate C. The molar ratio of intermediate B to metal hydroxide is 1:3. (4) After stirring and dispersing intermediate C, sodium iodide, and acetonitrile at 1.75 times the mass of intermediate C, nickel(II) ethylene glycol dimethyl ether was added and the mixture was refluxed and stirred for 19 h. The reaction mixture was diluted with ether and treated with 0.7 times the mass of intermediate C in 0.5 M hydrochloric acid aqueous solution. The organic layer was then separated and the aqueous layer was extracted with ether. The organic layer was washed twice with saturated sodium bicarbonate aqueous solution and saturated sodium chloride solution and dried on anhydrous sodium sulfate. The mixture was then concentrated under reduced pressure and eluented with a mixture of n-hexane and ethyl acetate at a volume ratio of 95:5 to obtain intermediate D by silica gel column chromatography. The molar ratio of sodium iodide, cerium trichloride heptahydrate, and intermediate C was 1:1.3:1. (5) Tris(2,2'-bipyridine) ruthenium dichloride, potassium carbonate, intermediate D, resorcinol, N,N-dimethylformamide, methanol, and tetrabutylammonium iodide were reacted under argon protection by irradiation with a 5W LED blue light and stirring for 15 h. The mixture was then cooled to 20 °C, kept at that temperature for 70 min, and then filtered, washed, and dried to obtain the product. The molar ratio of resorcinol, intermediate D, potassium carbonate, tetrabutylammonium iodide, and the second catalyst was 0.6:0.6:2.5:0.8:0.0040; the mass ratio of N,N-dimethylformamide to the intermediate was 31:1; and the volume ratio of N-dimethylformamide to methanol was 4:1.

[0036] Example 2 A method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine, comprising the following synthetic steps: (1) Under argon protection, nickel(II) glycol dimethyl ether, tetrahydroxy diboron and potassium carbonate were mixed and dispersed evenly. Then, 130 times the mass of biphenyl was added to dimethyl sulfoxide. Next, biphenyl and 2-amino-4,6-dichlorotriazine were added and reacted at 80°C for 6 hours. After the reaction was completed, the mixture was cooled to room temperature and quenched with 500 times the mass of biphenyl in water. Then, 1500 times the mass of biphenyl in ethyl acetate was added and the mixture was repeatedly extracted 3 times. The organic phase was collected and washed 3 times with 1500 times the mass of biphenyl in saturated brine. Then, anhydrous sodium sulfate was added for drying, filtration, and vacuum concentration to obtain an intermediate mixture. The molar ratio of biphenyl, 2-amino-4,6-dichlorotriazine, nickel(II) glycol dimethyl ether, tetrahydroxy diboron and potassium carbonate was 3.5:1:0.35:0.7:7. (2) Dissolve the intermediate mixture in hot toluene at 60°C until saturated, then let it stand and cool to room temperature, filter, and the solid obtained is intermediate B; concentrate the filtrate to obtain crude intermediate A and recrystallize it with a mixture of n-hexane and ethyl acetate at a volume ratio of 9:1 to obtain intermediate A, and put intermediate A into the reaction vessel of step (1) to continue the para-alkylation reaction. (3) Mix intermediate B with 5 times its mass of 2-butoxyethanol and heat to 148°C. Add sodium hydroxide and continue stirring and mixing. Keep the mixture warm for 3 hours. After the reaction is complete, cool to 80°C and quench with water. Add hydrochloric acid to adjust the pH to between 1 and 2. Then separate the organic layer, separate the product, wash with methanol and vacuum dry to obtain intermediate C. The molar ratio of intermediate B to metal hydroxide is 1:3.5. (4) After stirring and dispersing intermediate C, sodium iodide, and acetonitrile at 1.75 times the mass of intermediate C, nickel(II) ethylene glycol dimethyl ether was added and the mixture was refluxed and stirred for 20 h. The reaction mixture was diluted with ether and treated with 0.7 times the mass of intermediate C in 0.5 M hydrochloric acid aqueous solution. The organic layer was then separated and the aqueous layer was extracted with ether. The organic layer was washed twice with saturated sodium bicarbonate aqueous solution and saturated sodium chloride solution and dried on anhydrous sodium sulfate. The mixture was then concentrated under reduced pressure and eluented with a mixture of n-hexane and ethyl acetate at a volume ratio of 95:5 to obtain intermediate D by silica gel column chromatography. The molar ratio of sodium iodide, cerium trichloride heptahydrate, and intermediate C was 1.2:1.5:1. (5) Tris(2,2'-bipyridine) ruthenium dichloride, potassium carbonate, intermediate D, resorcinol, N,N-dimethylformamide, methanol, and tetrabutylammonium iodide were reacted under argon protection by irradiation with a 5W LED blue light and stirring for 18 h. The mixture was then cooled to 20 °C, kept at that temperature for 70 min, and then filtered, washed, and dried to obtain the product. The molar ratio of resorcinol, intermediate D, potassium carbonate, tetrabutylammonium iodide, and the second catalyst was 0.6:0.66:2.7:0.9:0.0045; the mass ratio of N,N-dimethylformamide to the intermediate was 31:1; and the volume ratio of N-dimethylformamide to methanol was 4:1.

[0037] Example 3 A method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine, comprising the following synthetic steps: (1) Under argon protection, nickel(II) glycol dimethyl ether, tetrahydroxy diboron and potassium carbonate were mixed and dispersed evenly. Then, 130 times the mass of biphenyl was added to dimethyl sulfoxide. Next, biphenyl and 2-amino-4,6-dichlorotriazine were added and reacted at 85°C for 7 hours. After the reaction was completed, the mixture was cooled to room temperature and quenched with 500 times the mass of biphenyl in water. Then, 1500 times the mass of biphenyl in ethyl acetate was added and the mixture was repeatedly extracted 3 times. The organic phase was collected and washed 3 times with 1500 times the mass of biphenyl in saturated brine. Then, anhydrous sodium sulfate was added for drying, filtration, and vacuum concentration to obtain an intermediate mixture. The molar ratio of biphenyl, 2-amino-4,6-dichlorotriazine, nickel(II) glycol dimethyl ether, tetrahydroxy diboron and potassium carbonate was 4:1:0.4:0.8:8. (2) Dissolve the intermediate mixture in hot toluene at 62°C until saturated, then let it stand and cool to room temperature, filter, and the solid obtained is intermediate B; concentrate the filtrate to obtain crude intermediate A and recrystallize it with a mixture of n-hexane and ethyl acetate at a volume ratio of 9:1 to obtain intermediate A, and put intermediate A into the reaction vessel of step (1) to continue the para-alkylation reaction. (3) Mix intermediate B with 5 times its mass of 2-butoxyethanol and heat to 150°C. Add sodium hydroxide and continue stirring and mixing. Keep the mixture warm for 3.5 h. After the reaction is complete, cool to 80°C and quench with water. Add hydrochloric acid to adjust the pH to between 1 and 2. Then separate the organic layer, separate the product, wash with methanol and vacuum dry to obtain intermediate C. The molar ratio of intermediate B to metal hydroxide is 1:4. (4) After stirring and dispersing intermediate C, sodium iodide, and acetonitrile at 1.75 times the mass of intermediate C, nickel(II) glycol dimethyl ether was added and the mixture was refluxed and stirred for 19-21 h. The reaction mixture was diluted with ether and treated with 0.7 times the mass of intermediate C in 0.5 M hydrochloric acid aqueous solution. The organic layer was then separated and the aqueous layer was extracted with ether. The organic layer was washed twice with saturated sodium bicarbonate aqueous solution and saturated sodium chloride solution and dried on anhydrous sodium sulfate. The mixture was then concentrated under reduced pressure and eluented with a mixture of n-hexane and ethyl acetate at a volume ratio of 95:5 to obtain intermediate D by silica gel column chromatography. The molar ratio of sodium iodide, cerium trichloride heptahydrate, and intermediate C was 1.2:1.5:1. (5) Tris(2,2'-bipyridine) ruthenium dichloride, potassium carbonate, intermediate D, resorcinol, N,N-dimethylformamide, methanol, and tetrabutylammonium iodide were reacted under argon protection by irradiation with a 5W LED blue light and stirring for 20 h. The mixture was then cooled to 20 °C, kept at that temperature for 70 min, and then filtered, washed, and dried to obtain the product. The molar ratio of resorcinol, intermediate D, potassium carbonate, tetrabutylammonium iodide, and the second catalyst was 0.6:0.72:2.9:1.0:0.0050; the mass ratio of N,N-dimethylformamide to the intermediate was 31:1; and the volume ratio of N-dimethylformamide to methanol was 4:1.

[0038] Comparative Example 1 The difference between Comparative Example 1 and Example 2 is that step (1) uses biphenyl and 2-amino-4,6-dichlorotriazine as raw materials and aluminum trichloride as catalyst to prepare an intermediate mixture, and performs an alkylation reaction based on aluminum trichloride using existing technology; the remaining steps are the same as in Example 2.

[0039] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that step (5) uses intermediate D and resorcinol as raw materials, conventional aluminum trichloride as catalyst to obtain the product, and performs alkylation reaction based on aluminum trichloride using existing technology; the remaining steps are the same as in Example 2.

[0040] Comparative Example 3 The difference between Comparative Example 3 and Example 2 is that steps (1) and (5) both use conventional aluminum trichloride as a catalyst and alkylation reaction based on aluminum trichloride using existing technology to obtain the product; the remaining steps are the same as in Example 2.

[0041] Example of effect Table 1 below shows the yields and purities of 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine in Examples 1-3 and Comparative Examples 1-2: Table 1 As shown in Table 1 above, the yields and purities of 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine prepared in Examples 1-3 were all high.

[0042] The difference between Comparative Example 1 and Example 2 is that step (1) uses biphenyl and 2-amino-4,6-dichlorotriazine as raw materials and aluminum trichloride as catalyst to prepare an intermediate mixture, and performs an alkylation reaction based on aluminum trichloride using existing technology; the difference between Comparative Example 2 and Example 2 is that step (5) uses intermediate D and resorcinol as raw materials and conventional aluminum trichloride as catalyst to prepare a product, and performs an alkylation reaction based on aluminum trichloride using existing technology; the difference between Comparative Example 3 and Example 2 is that steps (1) and (5) both use conventional aluminum trichloride as catalyst and perform an alkylation reaction based on aluminum trichloride using existing technology to prepare a product; compared with Comparative Examples 1 to 3, the yield and purity of 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine prepared in Examples 1 to 3 are higher.

[0043] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine, characterized in that, The synthesis steps include: (1) Under inert gas protection, biphenyl and 2-amino-4,6-dichlorotriazine were used as raw materials for para-alkylation reaction to obtain an intermediate mixture; (2) Dissolve the intermediate mixture in hot toluene until saturated, then let it stand and cool to room temperature, filter, and the solid obtained is intermediate B; concentrate the filtrate to obtain crude intermediate A, recrystallize crude intermediate A to obtain intermediate A, and continue the reaction of intermediate A in step (1); dry and concentrate the organic phase to obtain intermediate B; (3) React intermediate B with a metal hydroxide to obtain intermediate C; (4) Intermediate C is subjected to an iodination reaction to obtain intermediate D; (5) Intermediate D and resorcinol undergo ortho-alkylation reaction under the action of a second catalyst to obtain the product.

2. The method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine according to claim 1, characterized in that, The catalyst for the para-alkylation reaction is nickel(II) ethylene glycol dimethyl ether, the catalyst promoter is tetrahydroxydiboron, the solvent is dimethyl sulfoxide, the base is potassium carbonate, the reaction temperature is 75~85℃, and the reaction time is 5~7h.

3. The method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine according to claim 2, characterized in that, The molar ratio of biphenyl, 2-amino-4,6-dichlorotriazine, nickel(II) ethylene glycol dimethyl ether, tetrahydroxydiboron, and potassium carbonate is (3~4):1:(0.3~0.4):(0.6~0.8):(6~8).

4. The method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine according to claim 1, characterized in that, The temperature of the hot toluene is 58~62℃, and the solvent used for recrystallization is a mixture of n-hexane and ethyl acetate with a volume ratio of 9:

1.

5. The method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine according to claim 1, characterized in that, The metal hydroxide includes sodium hydroxide, and the molar ratio of intermediate B to the metal hydroxide is 1:(3~4); the reaction temperature is 145~150℃; and the reaction time is 2.5~3.5h.

6. The method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine according to claim 1, characterized in that, The iodizing agent for the iodination reaction is sodium iodide, the catalyst is cerium trichloride heptahydrate, the solvent is acetonitrile, and the reaction conditions are reflux for 19-21 hours.

7. The method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine according to claim 6, characterized in that, The molar ratio of sodium iodide, cerium trichloride heptahydrate, and intermediate C is (1~1.2):(1.3~1.5):

1.

8. The method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine according to claim 1, characterized in that, The second catalyst is tris(2,2'-bipyridine) ruthenium dichloride.

9. The method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine according to claim 1, characterized in that, The solvent for the ortho-alkylation reaction is a mixed solution of N,N-dimethylformamide and methanol in a volume ratio of 4:1; potassium carbonate and tetrabutylammonium iodide are also added during the ortho-alkylation reaction; the ortho-alkylation reaction conditions are nitrogen protection and light irradiation at room temperature, wherein the reaction time is 15-20 h and the wavelength of the light source is 450-480 nm.

10. The method for synthesizing 2,4-bis(4-biphenyl)-6-(2',4'-dihydroxy)phenyl-1,3,5-triazine according to claim 1, characterized in that, The molar ratio of resorcinol, intermediate D, potassium carbonate, tetrabutylammonium iodide, and the second catalyst is 0.6:(0.6~0.72):(2.5~2.9):(0.8~1.0):(0.0040~0.0050).

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