The invention relates to N, Napos; -diphenyl-N, Napos,-diphenyl-N, Napos; -bis (4-methylphenyl)-4, 4apos,-bis (4-methylphenyl)-4, 4apos; synthesis method of-biphenyl diamine
By using inexpensive catalysts and coupling reactions under mild conditions, combined with a simple post-processing procedure, the problems of high temperature and precious metal catalysis in existing p-TPD synthesis have been solved, achieving efficient and low-cost p-TPD production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-28
- Publication Date
- 2026-03-27
AI Technical Summary
Existing p-TPD synthesis methods suffer from problems such as high-temperature reactions, the use of precious metal catalysts, difficulty in removing polymer byproducts, and purification difficulties, resulting in high production costs and low efficiency.
Inexpensive copper acetylacetonate was used as a catalyst and N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide as a ligand. The purification process was simplified by coupling 4-methyldiphenylamine with 4,4'-dibromobiphenyl at a mild temperature. The post-treatment consisted of acid precipitation, decolorization and recrystallization.
A high-yield (91.3%) and low-cost p-TPD synthesis was achieved, avoiding high-temperature decomposition and the use of precious metals, making it suitable for large-scale production and improving production efficiency and product purity.
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Figure CN121735781A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of organic synthesis technology, specifically relating to a method for synthesizing the hole transport material N,N'-diphenyl-N,N'-bis(4-methylphenyl)-4,4'-biphenyldiamine (p-TPD). Background Technology
[0002] N,N'-Diphenyl-N,N'-bis(4-methylphenyl)-4,4'-biphenyldiamine, abbreviated as p-TPD (CAS No.: 20441-06-9), is a white solid powder. p-TPD is a widely used hole transport material. Under the influence of an electric field, it forms ammonium ion radicals, exhibiting excellent hole mobility and hole transport performance. Simultaneously, due to the presence of methyl groups, it has good solubility in resins and does not easily leach out of organic resins. p-TPD is mainly used in organic light-emitting diodes, solar cells, organic field-effect transistors, and electrostatic copiers.
[0003] Currently, p-TPD is produced worldwide by companies such as Takasago Kogyo Co., Ltd. in Japan and Shanghai Freon Chemical Co., Ltd. in China.
[0004] p-TPD can be synthesized using the following methods: Route 1:
[0005] Synthetic route one uses 4-methyltriphenylamine as a starting material for oxidative coupling to obtain p-TPD. Currently used oxidants include copper perchlorate hexahydrate (J.Org.Chem.2008,73,3245-3251), tetrachlorobenzoquinone (J.Org.Chem.2017,82,8958-8972), ferric chloride (Chem.Lett.1999,1,79-80 and CN102060711), and cerium ammonium nitrate (CN101830810). The oxidative coupling reaction or post-processing purification process easily forms trimeric or polymeric coupling byproducts, making purification difficult; at the same time, the cost of the raw material 4-methyltriphenylamine is relatively high.
[0006] Route 2:
[0007] Synthesis route two is N 4 N 4’ -Diphenyl-[1,1'-diphenyl]-4,4'-diamine is catalytically coupled with 4-methylhalobenzene.
[0008] Copper powder catalyzes the coupling reaction of benzidine and 4-methyliodobenzene (J. Mater. Chem., 2002, 12, 1703-1708). The reaction requires high temperature (190℃), and the material N...4 N 4’ -Diphenyl-[1,1'-diphenyl]-4,4'-diamine is relatively expensive. The palladium acetate-catalyzed coupling reaction of benzidine with 4-methylbromobenzene (Chem. Mater. 2010, 22, 1410-1419) requires 2% palladium acetate by mass, resulting in relatively high material costs and a yield of only 75%.
[0009] Route 3:
[0010] The third synthetic route involves the catalytic coupling of 4-methyldiphenylamine with halobiphenyls. Copper powder catalyzes the coupling of 4-methyldiphenylamine with 4,4'-diiodobiphenyl (US6242648, JP2005 / 162671, EP1553079, US2022 / 324791), but this reaction requires high temperatures (170-230℃), and the raw material 4,4'-diiodobiphenyl is relatively expensive. Palladium catalyzes the coupling of 4-methyldiphenylamine with 4,4'-dibromobiphenyl (Angew. Chem. 2023, 135, 44), but this reaction also requires expensive organophosphorus ligands.
[0011] Route 4:
[0012] Synthetic route four (CN108276300) involves the reaction of 4-methylaniline with o-chlorobenzoic acid as a starting material via the Ullmann reaction to obtain 2-[(4-methylphenyl)amino]benzoic acid. The product is then reacted with 4,4'-diiodobiphenyl via the Ullmann reaction, followed by high-temperature decarboxylation with cuprous oxide. This three-step synthetic route is relatively long, with the last two steps being high-temperature reactions. The three steps require a large amount of copper catalyst, and the second step uses the relatively expensive 4,4'-diiodobiphenyl, resulting in high material and production costs. Summary of the Invention
[0013] To address the aforementioned problems in the prior art, this invention provides a novel synthetic method for N,N'-diphenyl-N,N'-bis(4-methylphenyl)-4,4'-biphenyldiamine.
[0014] This invention utilizes inexpensive copper acetylacetonate as a catalyst and N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide as a ligand to catalyze the coupling of 4-methyldiphenylamine with 4,4'-dibromobiphenyl. The catalyst and ligand amounts in the catalytic system are relatively small, only 0.5 mol%, and the reaction temperature is relatively mild, with an internal temperature of 110℃. The post-treatment and purification processes are relatively simple, achieving a molar yield as high as 91.3%. This process significantly reduces production costs compared to existing patented technologies.
[0015] This invention includes the following technical solutions: A method for synthesizing N,N'-diphenyl-N,N'-bis(4-methylphenyl)-4,4'-biphenyldiamine includes the following steps: under an inert atmosphere, 4-methyldiphenylamine, 4,4'-dibromobiphenyl, a copper catalyst, N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide ligand, a base, and a solvent are mixed and heated to carry out a coupling reaction. After the reaction, the mixture is post-treated to obtain the N,N'-diphenyl-N,N'-bis(4-methylphenyl)-4,4'-biphenyldiamine.
[0016] Furthermore, in the above method, the heating temperature range is 100-120℃.
[0017] Furthermore, in the above method, the copper catalyst is copper acetylacetonate, and the amount used is 0.1-1 mol%, based on the molar amount of 4,4'-dibromobiphenyl.
[0018] Furthermore, in the above method, the amount of copper acetylacetone used is 0.5 mol.
[0019] Furthermore, in the above method, the amount of the N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide ligand is 0.1-1 mol%, based on the molar amount of 4,4'-dibromobiphenyl.
[0020] Furthermore, in the above method, the amount of the N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide ligand is 0.5 mol.
[0021] Furthermore, in the above method, the alkali is potassium hydroxide.
[0022] Furthermore, in the above method, the molar ratio of potassium hydroxide to 4,4'-dibromobiphenyl is 2.0-4.0 : 1.
[0023] Furthermore, in the above method, the solvent is dimethyl sulfoxide.
[0024] Furthermore, in the above method, the post-treatment includes: after cooling the reaction solution, adjusting it to a weakly acidic state with acid, adding methanol to precipitate, filtering, dissolving the filter cake in toluene, decolorizing it with activated carbon, and recrystallizing to obtain the N,N'-diphenyl-N,N'-bis(4-methylphenyl)-4,4'-biphenyldiamine.
[0025] Compared with the prior art, the present invention has the following outstanding advantages: 1. The use of inexpensive copper acetylacetone catalyst and N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide ligand, with a dosage as low as 0.5 mol%, significantly reduces catalyst cost and avoids the use of precious metals (such as palladium); 2. The reaction temperature is mild (100-120℃), energy consumption is low, and there are few side reactions, avoiding decomposition or polymerization problems caused by high temperature; 3. The raw material 4,4'-dibromobiphenyl has a lower cost and can replace the expensive 4,4'-diiodobiphenyl, making it more economical; 4. The post-processing is simple; high-purity products can be obtained through acid precipitation, decolorization, and recrystallization. There are few purification steps, making it suitable for large-scale operations. 5. The yield is as high as 91.3%, far exceeding that of existing methods (such as palladium catalysis, which yields 75%), thus improving production efficiency and product competitiveness; 6. The overall process is green and efficient, providing reliable support for the application of p-TPD in fields such as organic light-emitting diodes and solar cells. Attached Figure Description
[0026] Figure 1 The NMR spectrum of the product of Example 1; Figure 2 The image shows the HPLC chromatogram of the product from Example 1. Detailed Implementation
[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0028] The following is a list of raw materials for this invention.
[0029] Table 1 Raw Material List . Example 1
[0030] Under a nitrogen atmosphere, 10 L of dimethyl sulfoxide (DMSO), 1.41 kg of 4-methyldiphenylamine, 1.0 kg of 4,4'-dibromobiphenyl, 4.19 g of copper acetylacetonate (Cu(acac)2), 0.54 kg of potassium hydroxide (KOH), and 5.25 g of N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide were added sequentially to a 20 L reactor. The mixture was then heated to 110 °C and stirred for 16 h. The reaction solution was cooled to 20 °C, adjusted to a weakly acidic state with 2 M dilute hydrochloric acid, and then 10 L of methanol was added. The mixture was stirred for 1 h, filtered, and the filter cake was dissolved in 10 L of toluene, decolorized with activated carbon, and recrystallized to obtain 1.51 kg of a white solid product (molar yield 91.3%). The NMR spectrum of the product is shown below. Figure 1 As shown, the HPLC chromatogram is as follows: Figure 2 As shown.
[0031] The reaction route is as follows: . Example 2
[0032] Under a nitrogen atmosphere, 1 L of dimethyl sulfoxide, 141 g of 4-methyldiphenylamine, 100 g of 4,4'-dibromobiphenyl, 0.305 g of cuprous iodide (CuI), 54 g of potassium hydroxide, and 525 mg of N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide were added sequentially to a 2 L four-necked flask. The mixture was then heated to 110 °C and stirred for 16 h. TLC showed a small portion of the reactants reacting. 1 L of methanol was then added, and the mixture was stirred for 1 h. The mixture was filtered, and the filter cake was dissolved in 1 L of toluene, decolorized with activated carbon, and recrystallized to give 33.90 g of a white solid product (molar yield 20.5%). Example 3
[0033] Under a nitrogen atmosphere, 1 L of dimethyl sulfoxide, 141 g of 4-methyldiphenylamine, 100 g of 4,4'-dibromobiphenyl, 419 mg of copper acetylacetonate, 133 g of potassium carbonate, and 525 mg of N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide were added sequentially to a 2 L four-necked flask. The mixture was then heated to 110 °C and stirred for 16 h. TLC showed partial reaction of the starting material. 1 L of methanol was then added, and the mixture was stirred for 1 h. After filtration, the filter cake was dissolved in 1 L of toluene, decolorized with activated carbon, and recrystallized to give 119.74 g of a white solid product (molar yield 72.4%). Example 4
[0034] Under a nitrogen atmosphere, 1 L of N,N-dimethylformamide (DMF), 141 g of 4-methyldiphenylamine, 100 g of 4,4'-dibromobiphenyl, 419 mg of copper acetylacetonate, 54 g of potassium hydroxide, and 525 mg of N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide were added sequentially to a 2 L four-necked flask. The mixture was then heated to 110 °C and stirred for 16 h. TLC showed partial reaction of the starting material. 1 L of methanol was then added, and the mixture was stirred for 1 h. After filtration, the filter cake was dissolved in 1 L of toluene, decolorized with activated carbon, and recrystallized to obtain 138.26 g of a white solid product (molar yield 83.6%). Example 5
[0035] Under a nitrogen atmosphere, 1 L of toluene, 141 g of 4-methyldiphenylamine, 100 g of 4,4'-dibromobiphenyl, 419 mg of copper acetylacetonate, 54 g of potassium hydroxide, and 525 mg of N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide were added sequentially to a 2 L four-necked flask. The mixture was then heated to 110 °C and stirred for 16 h. TLC showed partial reaction of the starting material. 1 L of methanol was then added, and the mixture was stirred for 1 h. After filtration, the filter cake was dissolved in 1 L of toluene, decolorized with activated carbon, and recrystallized to give 108.66 g of a white solid product (molar yield 65.7%). Example 6
[0036] Under a nitrogen atmosphere, 1 L of dimethyl sulfoxide, 141 g of 4-methyldiphenylamine, 100 g of 4,4'-dibromobiphenyl, 419 mg of copper acetylacetonate, 54 g of potassium hydroxide, and 525 mg of N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide were added sequentially to a 2 L four-necked flask. The mixture was then heated to 100 °C and stirred for 16 h. TLC showed partial reaction of the starting material. 1 L of methanol was then added, and the mixture was stirred for 1 h. After filtration, the filter cake was dissolved in 1 L of toluene, decolorized with activated carbon, and recrystallized to give 134.79 g of a white solid product (molar yield 81.5%). Example 7
[0037] Under a nitrogen atmosphere, 1 L of dimethyl sulfoxide, 141 g of 4-methyldiphenylamine, 100 g of 4,4'-dibromobiphenyl, 419 mg of copper acetylacetonate, 54 g of potassium hydroxide, and 525 mg of N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide were added sequentially to a 2 L four-necked flask. The mixture was then heated to 120 °C and stirred for 16 h. TLC showed partial reaction of the starting material. 1 L of methanol was then added, and the mixture was stirred for 1 h. After filtration, the filter cake was dissolved in 1 L of toluene, decolorized with activated carbon, and recrystallized to give 138.10 g of a white solid product (molar yield 83.2%).
[0038] Summary of Implementation Examples: For the same molar amount of catalytic copper acetylacetone, the catalytic activity was significantly higher than that of cuprous iodide; the reaction yield using potassium hydroxide as the base was significantly higher than that using potassium carbonate; the reaction yield using dimethyl sulfoxide as the solvent was significantly higher than that using N,N-dimethylformamide and toluene; the optimal reaction temperature was 110℃ (better than 110℃ and 120℃). A summary is shown in Table 2.
[0039] Table 2: Summary of Examples
[0040] Through comparative analysis of Examples 1-7, the synthesis method of the present invention has been systematically optimized in terms of catalyst, base, solvent and reaction temperature.
[0041] 1) Catalyst selection: The catalytic activity of copper acetylacetonate (Example 1, yield 91.3%) was significantly higher than that of cuprous iodide (Example 2, yield 20.5%), indicating that copper acetylacetonate has higher efficiency and selectivity in coupling reactions.
[0042] 2) Effect of base: Potassium hydroxide (Example 1, yield 91.3%) is better than potassium carbonate (Example 3, yield 72.4%) as a base because it can promote the reaction more effectively.
[0043] 3) Solvent optimization: Dimethyl sulfoxide (Example 1, yield 91.3%) was the solvent with the highest yield, which was better than N,N-dimethylformamide (Example 4, yield 83.6%) and toluene (Example 5, yield 65.7%), possibly related to solvent polarity and solubility.
[0044] 4) Temperature control: The optimal reaction temperature was 110℃ (Example 1, yield 91.3%). Temperatures above 100℃ (Example 6, yield 81.5%) and 120℃ (Example 7, yield 83.2%) balanced the reaction rate and side reaction control.
[0045] In summary, the optimal process parameters are: copper acetylacetone catalyst (0.5 mol%), N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide ligand (0.5 mol%), potassium hydroxide base (molar ratio 3:1), dimethyl sulfoxide solvent, and reaction temperature 110℃. These conditions ensure high yield, low cost, and ease of operation, providing a reliable basis for industrial applications.
[0046] It is worth noting that the above description of the embodiments focuses on illustrating the technical solution of the present invention, rather than precisely defining its scope of protection. Those skilled in the art should understand that appropriate adjustments and optimizations can be made based on the technical details disclosed in the embodiments of the present invention, or equivalent substitutions can be implemented for individual or even all technical elements. Such adjustments and substitutions will not deviate from the core essence of the technical solution of the present invention and should be included within the technical protection scope of the embodiments of the present invention. In short, the protection of the present invention should not be limited to the concrete presentation of the above embodiments, but broadly covers all equivalent changes and improvements that do not depart from its basic concept. In summary, the protection definition of the present invention should be based on the statement of the claims, and the above embodiments are only used as a reference guide for understanding the present invention.
Claims
1. A method for synthesizing N,N'-diphenyl-N,N'-bis(4-methylphenyl)-4,4'-biphenyldiamine, characterized in that, Includes the following steps: Under an inert atmosphere, 4-methyldiphenylamine, 4,4'-dibromobiphenyl, a copper catalyst, N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide ligand, a base, and a solvent are mixed and heated to carry out a coupling reaction. After post-treatment, the N,N'-diphenyl-N,N'-bis(4-methylphenyl)-4,4'-biphenyldiamine is obtained.
2. The method according to claim 1, characterized in that, The heating temperature range is 100-120℃.
3. The method according to claim 1, characterized in that, The copper catalyst is copper acetylacetonate, used in an amount of 0.1-1 mol%, based on the molar amount of 4,4'-dibromobiphenyl.
4. The method according to claim 3, characterized in that, The amount of copper acetylacetonate used is 0.5 mol.
5. The method according to claim 1, characterized in that, The amount of the N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide ligand is 0.1-1 mol%, based on the molar amount of 4,4'-dibromobiphenyl.
6. The method according to claim 5, characterized in that, The amount of the N,N'-bis(4-hydroxy-2,6-dimethylphenyl)amide ligand used was 0.5 mol.
7. The method according to claim 1, characterized in that, The alkali is potassium hydroxide.
8. The method according to claim 7, characterized in that, The molar ratio of potassium hydroxide to 4,4'-dibromobiphenyl is 2.0-4.0 :
1.
9. The method according to claim 1, characterized in that, The solvent is dimethyl sulfoxide.
10. The method according to claim 1, characterized in that, The post-treatment includes: after cooling the reaction solution, adjusting it to a weakly acidic state with acid, adding methanol to precipitate, filtering, dissolving the filter cake in toluene, decolorizing it with activated carbon, and recrystallizing to obtain the N,N'-diphenyl-N,N'-bis(4-methylphenyl)-4,4'-biphenyldiamine.