Synthesis method of tetra (4-aminobenzene) ethylene

Abstract

The invention provides a synthetic method of tetrakis (4-aminobenzene) ethylene, belongs to the technical field of organic luminescent molecules, and aims to solve the technical problems that the tetrakis (4-aminobenzene) ethylene is difficult to synthesize in quantity and low in purity. The synthetic method of the tetra (4-aminobenzene) ethylene comprises the following steps: (1) mixing tetra (4-bromobenzene) ethylene, benzophenoneimine, a catalyst, an alkaline additive and a solvent I, and reacting to obtain an intermediate; (2) acidifying the intermediate to obtain tetra (4-aminobenzene) ethylene salt; and (3) alkalizing the tetra (4-aminobenzene) ethylene salt to obtain tetra (4-aminobenzene) ethylene. Compared with the prior art, the product obtained by the method has high purity and is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the technical field of organic light-emitting molecules, and particularly relates to a tetra(4-aminophenyl)ethylene. Background Technology

[0002] The concept of aggregation-induced emission (AIE) was first proposed by Tang Benzhong et al. in 2001. Over the past two decades, AIE materials have been widely applied in various fields such as optoelectronic materials and biosensing. In recent years, related research has been repeatedly recognized as a research hotspot in the fields of chemistry and materials by the Documentation and Information Center of the Chinese Academy of Sciences, Thomson Reuters, and *Nature*.

[0003] Tetra(4-aminophenyl)ethylene is one of the most prominent AIE molecules. However, its synthesis faces numerous challenges, primarily low purity and difficulty in large-scale synthesis. The reported synthetic methods mainly consist of four approaches (as shown below): .

[0004] (1) Tetra(4-nitrobenzene)ethylene was prepared by nitration of tetraphenylethylene with fuming nitric acid, followed by reduction with a Raney nickel / hydrazine hydrate system (Eur. J. Org. Chem., 2006, 3395); (2) Tetra(4-nitrobenzene)ethylene was prepared by reduction with a Pd / C / hydrazine hydrate system (J. Am. Chem. Soc, 2017, 139, 7172); (3) Tetra(4-nitrobenzene)ethylene was prepared by the McMurry reaction from 4,4′-diaminobenzophenone (J. Mol. Struct., 2022, 1264, 133294); (4) Tetra(4-nitrobenzene)ethylene was prepared by reflux of tin and concentrated hydrochloric acid (Anal. Chem., 2016, 88, 7853). Studies have shown that the synthesis of tetra(4-nitrobenzene)ethylene via methods (3) and (4) is quite difficult. Currently, the most widely used methods are (1) and (2). Experiments show that it is difficult to synthesize tetra(4-aminophenyl)ethylene in large quantities using methods (1) and (2), and the products have low purity, poor solubility, and poor color. For example, the product prepared by method (1) is often red. Summary of the Invention

[0005] To address the technical problem of the difficulty in synthesizing tetra(4-aminophenyl)ethylene in large quantities and the low purity, this invention proposes a method for synthesizing tetra(4-aminophenyl)ethylene. This method is highly efficient, yields high-purity products, and has significant prospects for industrial application.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows: A method for synthesizing tetra(4-aminophenyl)ethylene includes the following steps: (1) Tetra(4-bromophenyl)ethylene, benzophenone imine (Ph2C=NH), catalyst, basic additive and solvent I are mixed and reacted to obtain an intermediate; (2) The intermediate is acidified to obtain tetra(4-aminophenyl)ethylene salt; (3) Tetra(4-aminophenyl)ethylene salt is alkalized to obtain tetra(4-aminophenyl)ethylene.

[0007] The molar ratio of tetra(4-bromophenyl)ethylene to benzophenone imine is 1:5; the molar ratio of tetra(4-bromophenyl)ethylene to alkaline additive is 1:6; and the concentration of tetra(4-bromophenyl)ethylene in solvent I in step (1) is 0.05-0.5 mol / L.

[0008] The catalyst includes a palladium catalyst and a ligand.

[0009] It should be noted that, for experimental safety, if the amount of tetra(4-bromophenyl)ethylene added is too high, Ph2C=NH should be prepared as a toluene solution and added dropwise to the reaction flask through a constant pressure dropping funnel.

[0010] The palladium catalyst is tris(dibenzylacetone)palladium (Pd2(dba)3), dibenzylacetonepalladium (Pd(dba)2), tetra(triphenylphosphine)palladium (Pd(PPh3)4), palladium chloride, or [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride (PdCl2(dppf)); the ligand is triphenylphosphine (PPh3), tri-tert-butylphosphine (tBu3P), tricyclohexylphosphine (Cy3P), 2,2'-bis(diphenylphosphine)-1,1'-binaphthyl (rac-BINAP), 1,1'-bis(diphenylphosphine)ferrocene (dppf), 4,5-bisdiphenylphosphine-9,9-dimethyloxanthracene (Xantphos), or N-heterocyclic carbene (NHC).

[0011] The amount of palladium catalyst used is 0.1%-5% of the amount of tetra(4-bromophenyl)ethylene; the molar ratio of the ligand to the palladium catalyst is 1:1-4.

[0012] Solvent I is toluene, xylene, tetrahydrofuran, N,N-dimethylformamide, or N,N-dimethylacetamide; the alkaline additive is sodium tert-butoxide (NaOtBu), potassium tert-butoxide (KOtBu), cesium carbonate, or sodium methoxide.

[0013] The reaction temperature in step (1) is 100-120℃ and the time is 6-24h.

[0014] The acidification step is as follows: the intermediate is added to solvent II for dissolution, then acid is added until a precipitate is formed, and after filtration and washing, tetra(4-aminophenyl)ethylene salt is obtained.

[0015] The alkalization step is as follows: dissolve tetra(4-aminophenyl)ethylene salt in water, then add alkali until a precipitate forms, and obtain tetra(4-aminophenyl)ethylene after filtration and washing.

[0016] The acid is hydrochloric acid, sulfuric acid, or nitric acid; the solvent II is toluene, xylene, tetrahydrofuran, N,N-dimethylformamide, or N,N-dimethylacetamide; and the base is sodium hydroxide, potassium hydroxide, or ammonia.

[0017] The beneficial effects of this invention are: (1) This method significantly improves product yield and reduces production energy consumption by optimizing the reaction path. At the same time, it has high raw material utilization and few by-products, which reduces raw material waste and subsequent separation costs, and greatly improves the economics of industrial production.

[0018] (2) No complex special equipment or extreme reaction conditions (such as ultra-high temperature or ultra-high pressure) are required. The operation process is highly standardized, making it easy for workers to quickly master and reducing the risk caused by human error. In addition, the reaction system has good stability and the side reactions are controllable, reducing potential safety hazards.

[0019] (3) The product has high purity (98% can be achieved through simple post-processing, and the yield can reach 80%), avoiding the product performance degradation caused by impurities in traditional methods, and is especially suitable for fields with strict purity requirements.

[0020] (4) This method breaks through the bottlenecks of low efficiency, poor purity, and complex processes in traditional synthetic routes, providing a brand-new technical solution for the synthesis of tetra(4-aminophenyl)ethylene and its derivatives. This invention not only has significant advantages in production efficiency, product quality, and cost control, but also takes into account safety, environmental protection, and industrial feasibility, laying a solid foundation for the large-scale application of tetra(4-aminophenyl)ethylene and having extremely high economic value and social significance. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 The 1H NMR spectrum of intermediate (II).

[0023] Figure 2 The 1H NMR spectrum is for tetra(4-aminophenyl)ethylene(III).

[0024] Figure 3 The HPLC chromatogram is for tetra(4-aminophenyl)ethylene(III).

[0025] Figure 4 Optical diagram of tetra(4-aminophenyl)ethylene(III). Detailed Implementation

[0026] 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. 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.

[0027] Example 1 A method for synthesizing tetra(4-aminophenyl)ethylene, the preparation process is shown in the following formula: The specific synthesis method includes the following steps: (1) Preparation of intermediate (II): Add 150 g (0.23 mol) of tetra(4-bromophenyl)ethylene (I) and 10 g (1.16 mol) of Ph₂C=NH₂ to a 3000 mL three-necked round-bottom flask containing a magnetic inlet. rac 3.25 g (0.0052 mol) of BINAP, 133 g (1.39 mol) of NaOtBu, and 2000 mL of toluene were stirred at room temperature for 30 min under nitrogen protection. Then, 31.59 g (0.0017 mol) of Pd2(dba) was added, and the mixture was heated to 110 °C. o Reflux at C for 12 h. After the reaction solution cooled to room temperature, dilute with 1000 mL of DCM, filter through diatomaceous earth to obtain the filtrate, remove most of the solvent by vortexing to obtain the crude product, and recrystallize from ethanol to obtain high-purity intermediate (II). Its 1H NMR spectrum (… 1 H NMR) such as Figure 1 As shown, the position of the peak and the integral area indicate that the chemical structure of intermediate (II) is correct and its purity is high.

[0028] (2) Preparation of tetra(4-aminophenyl)ethylene: High-purity intermediate (II) was added to 1000 mL of THF and stirred at room temperature for 30 min until completely dissolved. Then, 75 mL of concentrated hydrochloric acid was slowly added, resulting in a large amount of precipitate. The precipitate was filtered to obtain tetra(4-aminophenyl)ethylene hydrochloride, which was then dissolved in 2000 mL of water. The pH was adjusted to ~8 with 10% NaOH aqueous solution, resulting in a large amount of precipitate. After filtration, washing with water, and drying, 72.69 g of high-purity tetra(4-aminophenyl)ethylene (III) was obtained (yield 80%). Figure 4 (As shown). 1 H NMR image as follows Figure 2 As shown, the peak position and integral area are consistent with the chemical structure of tetra(4-aminophenyl)ethylene(III). Quantitative analysis... 1 ¹H NMR indicated a purity of 98.5%. To further analyze the purity of tetra(4-aminophenyl)ethylene(III), high-performance liquid chromatography (HPLC) was performed (e.g., ...). Figure 3 As shown in the figure, the mobile phase was acetonitrile. HPLC analysis indicated that the sample purity was 97.4%.

[0029] Example 2 A method for synthesizing tetra(4-aminophenyl)ethylene, the preparation process is shown in the following formula: The specific synthesis method includes the following steps: (1) Preparation of intermediates: Add 324 g (0.5 mol) of tetra(4-bromophenyl)ethylene (I) and 362 g (2 mol) of Ph₂C=NH₃ to a 3000 mL three-necked round-bottom flask containing a magnetic inlet. rac -BINAP 0.325 g (0.00052 mol), NaOtBu 240 g (2.5 mol), and toluene 1000 mL were stirred at room temperature for 30 min under nitrogen protection. Then, Pd2(dba) 30.47 g (0.0005 mol) was added, and the mixture was heated to 100 °C. o Reflux at C for 24 h. After the reaction solution cools to room temperature, dilute with 1000 mL of DCM, filter through diatomaceous earth to obtain the filtrate, remove most of the solvent by vortexing to obtain the crude product, and recrystallize from ethanol to obtain the high-purity intermediate (II).

[0030] (2) Preparation of tetra(4-aminophenyl)ethylene: High-purity intermediate (II) was added to 2000 mL of THF and stirred at room temperature for 30 min to dissolve it completely. Then, 100 mL of concentrated hydrochloric acid was slowly added, and a large amount of precipitate was formed. The precipitate was filtered to obtain tetra(4-aminophenyl)ethylene hydrochloride, which was then dissolved in 2000 mL of water. The pH value was adjusted to ~8 with 10% NaOH aqueous solution, and a large amount of precipitate was formed. The precipitate was then filtered, washed with water, and dried to obtain high-purity tetra(4-aminophenyl)ethylene (III).

[0031] Example 3 A method for synthesizing tetra(4-aminophenyl)ethylene, the preparation process is shown in the following formula: The specific synthesis method includes the following steps: (1) Preparation of intermediates: Add 64.8 g (0.1 mol) of tetra(4-bromophenyl)ethylene(I) and 108.6 g (0.6 mol) of Ph₂C=NH₃ to a 3000 mL three-necked round-bottom flask containing a magnetic inlet. rac -BINAP 0.75 g (0.00125 mol), NaOtBu 96 g (1 mol), and toluene 2000 mL were stirred at room temperature for 30 min under nitrogen protection. Then, Pd2(dba) 34.7 g (0.005 mol) was added, and the mixture was heated to 120 °C. o Reflux at C for 12 h. After the reaction solution cools to room temperature, dilute with 1000 mL of DCM, filter through diatomaceous earth to obtain the filtrate, remove most of the solvent by vortexing to obtain the crude product, and recrystallize from ethanol to obtain the high-purity intermediate (II).

[0032] (2) Preparation of tetra(4-aminophenyl)ethylene: High-purity intermediate (II) was added to 2000 mL of THF and stirred at room temperature for 30 min to dissolve it completely. Then, 50 mL of concentrated hydrochloric acid was slowly added, and a large amount of precipitate was formed. The precipitate was filtered to obtain tetra(4-aminophenyl)ethylene hydrochloride, which was then dissolved in 2000 mL of water. The pH value was adjusted to ~8 with 10% NaOH aqueous solution, and a large amount of precipitate was formed. After filtration, rinsing with water, and drying, high-purity tetra(4-aminophenyl)ethylene (III) was obtained.

[0033] Example 4 A method for synthesizing tetra(4-aminophenyl)ethylene, the preparation process is shown in the following formula: The specific synthesis method includes the following steps: (1) Preparation of intermediates: Add tetra(4-bromophenyl)ethylene (I) (1 mol) and Ph₂C=NH₃ (5 mol) to a 10000 mL three-necked round-bottom flask containing a magnetic induction magnet. rac BINAP (0.01 mol), KOtBu (7 mol), and xylene (5000 mL) were stirred at room temperature for 30 min under nitrogen protection. Then, Pd2(dba)3 (0.02 mol) was added, and the mixture was heated to 110 °C. o Reflux at C for 12 h. After the reaction solution cools to room temperature, dilute with 3000 mL of DCM, filter through diatomaceous earth to obtain the filtrate, remove most of the solvent by vortexing to obtain the crude product, and recrystallize from ethanol to obtain the high-purity intermediate (II).

[0034] (2) Preparation of tetra(4-aminophenyl)ethylene: High-purity intermediate (II) was added to 3000 mL of THF and stirred at room temperature for 30 min until completely dissolved. Then, 200 mL of concentrated hydrochloric acid was slowly added, resulting in a large amount of precipitate. The precipitate was filtered to obtain tetra(4-aminophenyl)ethylene hydrochloride, which was then dissolved in 2000 mL of water. The pH was adjusted to ~8 with 10% NaOH aqueous solution, resulting in a large amount of precipitate. After filtration, rinsing with water, and drying, high-purity tetra(4-aminophenyl)ethylene (III) was obtained. Optical photographs are shown below. Figure 4 As shown.

[0035] Example 5 A method for synthesizing tetra(4-aminophenyl)ethylene, the preparation process is shown in the following formula: The specific synthesis method includes the following steps: (1) Preparation of intermediates: In a 3000 mL three-necked round-bottom flask equipped with a magnetic stir bar, add tetra(4-bromophenyl)ethylene (I) (0.1 mol), Ph₂C=NH₃ (0.5 mol), triphenylphosphine (0.0001 mol), cesium carbonate (0.5 mol), and 1000 mL of toluene. Stir at room temperature for 30 min under nitrogen protection, then add tris(dibenzylacetone)dipalladium (0.0001 mol) and heat to 110 °C. o Reflux at C for 12 hours. After the reaction solution cools to room temperature, dilute with 1000 mL of DCM, filter through diatomaceous earth to obtain the filtrate, remove most of the solvent by vortexing to obtain the crude product, and recrystallize from ethanol to obtain the high-purity intermediate (II).

[0036] (2) Preparation of tetra(4-aminophenyl)ethylene: High-purity intermediate (II) was added to 1000 mL of N,N-dimethylformamide and stirred at room temperature for 30 min to dissolve it completely. Then, 50 mL of nitric acid was slowly added, and a large amount of precipitate was formed. After filtration, tetra(4-aminophenyl)ethylene nitrate was obtained. It was then dissolved in 2000 mL of water, and the pH value was adjusted to ~8 with 10% NaOH aqueous solution. A large amount of precipitate was formed. After filtration, rinsing with water, and drying, high-purity tetra(4-aminophenyl)ethylene (III) was obtained.

[0037] Example 6 A method for synthesizing tetra(4-aminophenyl)ethylene, the preparation process is shown in the following formula: The specific synthesis method includes the following steps: (1) Preparation of intermediates: In a 3000 mL three-necked round-bottom flask equipped with a magnetic stir bar, add tetra(4-bromophenyl)ethylene (I) (0.1 mol), Ph₂C=NH₃ (0.5 mol), 4,5-bis(diphenylphosphine-9,9-dimethyloxanthracene) or N-heterocyclic carbene (0.0001 mol), sodium methoxide (0.5 mol), and 1000 mL of toluene. Stir at room temperature for 30 min under nitrogen protection, then add palladium dibenzylacetone (0.0001 mol) and heat to 110 °C. o Reflux at C for 12 h. After the reaction solution cools to room temperature, dilute with 1000 mL of DCM, filter through diatomaceous earth to obtain the filtrate, remove most of the solvent by vortexing to obtain the crude product, and recrystallize from ethanol to obtain the high-purity intermediate (II).

[0038] (2) Preparation of tetra(4-aminophenyl)ethylene: High-purity intermediate (II) was added to 1000 mL of toluene and stirred at room temperature for 30 min to dissolve it completely. Then, 50 mL of nitric acid was slowly added, and a large amount of precipitate was formed. The precipitate was filtered to obtain tetra(4-aminophenyl)ethylene nitrate, which was then dissolved in 1000 mL of water. The pH value was adjusted to ~8 with 10% KOH aqueous solution, and a large amount of precipitate was formed. After filtration, rinsing with water, and drying, high-purity tetra(4-aminophenyl)ethylene (III) was obtained.

[0039] The above description is only a preferred embodiment of the present invention and is 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 the synthesis of tetra(4-aminophenyl)ethylene, characterized in that, The method comprises the following steps: (1) mixing tetrakis(4-bromophenyl)ethylene, benzophenone imine, a catalyst, a basic additive and a solvent I, and then performing a reaction to obtain an intermediate; (2) acidifying the intermediate to obtain tetrakis(4-aminophenyl)ethylene salt; (3) alkalinizing the tetrakis(4-aminophenyl)ethylene salt to obtain tetrakis(4-aminophenyl)ethylene.

2. The method of claim 1, wherein the synthesis of tetra(4-aminophenyl)ethylene is characterized by, The mass ratio of the tetrakis(4-bromophenyl)ethylene to the benzophenone imine is 1:4-6; the mass ratio of the tetrakis(4-bromophenyl)ethylene to the basic additive is 1:5-10; and the concentration of the tetrakis(4-bromophenyl)ethylene in the solvent I in the step (1) is 0.05-0.5 mol / L.

3. The method of claim 2, wherein the synthesis of tetra(4-aminophenyl)ethylene is characterized by, The catalyst comprises a palladium catalyst and a ligand.

4. The method of claim 3, wherein the synthesis of tetra(4-aminophenyl)ethylene is characterized by, The palladium catalyst is tris(dibenzylideneacetone)dipalladium, palladium dibenzylideneacetone, tetrakis(triphenylphosphine)palladium, palladium chloride or [1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium; and the ligand is triphenylphosphine, tri-tert-butylphosphine, tricyclohexylphosphine, 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl, 1,1'-bis(diphenylphosphino)ferrocene, 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene or N-heterocyclic carbene.

5. The method of claim 4, wherein the synthesis of tetra(4-aminophenyl)ethylene is characterized by, The amount of the palladium catalyst is 0.1%-5% of the amount of the tetrakis(4-bromophenyl)ethylene; and the mass ratio of the ligand to the palladium catalyst is 1:1-4.

6. The method of claim 5, wherein the synthesis of tetra(4-aminophenyl)ethylene is characterized by, The solvent I is toluene, xylene, tetrahydrofuran, N,N-dimethylformamide or N,N-dimethylacetamide; and the basic additive is sodium tert-butoxide, potassium tert-butoxide, cesium carbonate or sodium methoxide.

7. The method of synthesis of tetra(4-aminophenyl)ethylene according to any one of claims 1 to 6, characterized in that, The reaction temperature in the step (1) is 100-120 ℃, and the reaction time is 6-24 h.

8. The method of claim 7, wherein the synthesis of tetra(4-aminophenyl)ethylene is characterized by, The acidification step is: dissolving the intermediate in a solvent II, and then adding an acid until a precipitate is generated, and then filtering and washing to obtain the tetrakis(4-aminophenyl)ethylene salt.

9. The method of claim 8, wherein the synthesis of tetra(4-aminophenyl)ethylene is characterized by, The alkalinization step is: dissolving the tetrakis(4-aminophenyl)ethylene salt in water, and then adding a base until a precipitate is generated, and then filtering and washing to obtain the tetrakis(4-aminophenyl)ethylene.

10. The method of claim 9, wherein the synthesis of tetra(4-aminophenyl)ethylene is characterized by, The acid is hydrochloric acid, sulfuric acid or nitric acid; the solvent II is toluene, xylene, tetrahydrofuran, N,N-dimethylformamide or N,N-dimethylacetamide; and the base is sodium hydroxide, potassium hydroxide or ammonia.

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