A method for synthesizing 9,10-bis[N-(2-naphthyl)anilino]anthracene without metal catalysis

Abstract

The invention discloses a method for synthesizing 9,10-bis[N-(2-naphthyl)anilino]anthracene without metal catalysis, relates to the technical field of organic luminescent material preparation, and aims to solve the problems of large amounts of waste generated and complex steps in existing methods. The method comprises the following steps: adding refined anthracene, N-phenyl-2-naphthylamine, an oxidant, an additive, and a solvent into a reaction vessel under an oxidizing atmosphere; heating the reaction after the addition is completed, heating the temperature to reflux or 80°C to 120°C, reacting for 8 to 15 hours, and cooling the temperature to room temperature, directly filtering to obtain a crude product, and separating to obtain 9,10-bis[N-(2-naphthyl)anilino]anthracene. The method has simple steps and is easy to operate, requiring only mixing all raw materials, heating the reaction, and then separating. The raw materials are low in cost and readily available, do not require a catalyst, are free of metal, and effectively avoid metal residues in the later stage. The method has simple post-processing, reduces the amount of three wastes, and has excellent purity and considerable yield, thus conforming to the development direction of green chemistry.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of organic light-emitting materials, and particularly to a method for synthesizing metal-free catalytic 9,10-bis[N-(2-naphthyl)anilino]anthracene. Background Art

[0002] Organic light-emitting diodes (OLEDs) are the current hottest new display technology due to their advantages such as flexibility, wide color gamut, wide viewing angle, and low power consumption, and are widely used in various fields such as smartphones, in-vehicle displays, VR headsets, tablet computers, and large-size TVs. Among the three-color materials of OLED panels, the development of blue-light materials is relatively slow compared to green-light and red-light materials.

[0003] At present, blue-light organic light-emitting materials mainly focus on some classic compound systems such as triarylamine derivatives, anthracene-based, carbazole derivatives, and metal complexes. 9,10-Bis[N-(2-naphthyl)anilino]anthracene contains triarylamine fragments and anthracene parent slices, and has the characteristics of the above parent slices, so it is an ideal intermediate for blue-light emitting materials.

[0004] At present, the synthesis of such compounds is mainly achieved based on the Buchwald-Hartwig coupling strategy. Using 9,10-dibromoanthracene as the anthracene source and N-phenyl-2-naphthylamine as the amine source, the construction of the C-N bond is realized with the help of Pd catalysis, and the precipitated solid can obtain a high-purity yellow solid through crystallization. In the above synthesis route, 9,10-bis[N-(2-naphthyl)anilino]anthracene has poor solubility and usually requires a large amount of high-boiling polar solvents for recrystallization (mass-volume ratio 1:30), so the energy consumption is high and there are many three wastes. In addition, it is necessary to reduce the residual metal Pd by column chromatography, which increases the difficulty of post-treatment. Therefore, there is an urgent need for a method for synthesizing metal-free catalytic 9,10-bis[N-(2-naphthyl)anilino]anthracene to solve this problem. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for synthesizing metal-free catalytic 9,10-bis[N-(2-naphthyl)anilino]anthracene to solve the problems of more waste and complex steps generated by the existing methods.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A method for synthesizing metal-free catalytic 9,10-bis[N-(2-naphthyl)anilino]anthracene, which is characterized by including the following contents: Under an oxidative atmosphere, add anthracene, N-phenyl-2-naphthylamine, an oxidant, an additive, and a solvent into a reaction vessel; after the feeding is completed, raise the temperature for reaction, raise the temperature to reflux or 80 °C to 120 °C, react for 8 to 15 hours, after the reaction is completed, lower the temperature to room temperature and directly filter to obtain a crude product, and 9,10-bis[N-(2-naphthyl)anilino]anthracene can be obtained after separation.

[0007] Preferably, the oxidation atmosphere is air or oxygen.

[0008] Preferably, the oxidant is selected from at least one of 30% hydrogen peroxide, sodium persulfate, and oxygen.

[0009] Preferably, the additive is selected from at least one of potassium phosphate, pivalic acid, and 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0010] Preferably, the solvent is selected from at least one of xylene, 1,2-dichloroethane, and ethanol.

[0011] Preferably, the dosage ratio of anthracene, N-phenyl-2-naphthylamine, oxidant, additive, and solvent is 1 mol:(2 - 2.2 mol):(3 - 3.3 mol):(2 - 2.2 mol):(1.5 - 2 L).

[0012] Preferably, stirring is carried out while raising the temperature, and the rotation speed is adjusted to 300 rpm.

[0013] Preferably, the separation is carried out by adding water and n-hexane for rinsing, and the product purity > 99%.

[0014] Preferably, the separation is carried out by adding water and ethyl acetate for extraction, and the organic layer is desolvated to obtain a crude product for column chromatography, and the product purity > 99.5%.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] 1. The synthesis method of metal-free catalytic 9,10-bis[N-(2-naphthyl)anilino]anthracene, under an oxidation atmosphere, assisted by an additive, oxidizes electron-rich anthracene by an oxidant to obtain a radical cation, and N-phenyl-2-naphthylamine realizes nucleophilic addition to complete the construction of the C-N bond. Under the assistance of the additive, further oxidation and deprotonation are carried out to obtain an anthracene precursor modified with ammonia at the 9-position, and the solubility is greatly improved compared with anthracene. Due to the modification of the amine, the electron-rich system is further improved, so the above-mentioned amine modification process can occur again, and finally an anthracene precursor modified with diamine at the 9,10-positions is obtained; the synthesis method has simple steps and is easy to operate, only requiring mixing all raw materials, raising the temperature for reaction, and then separating, and no nitrogen environment is required, and it can be realized under air conditions, and it is easier to control and apply to large-scale production compared with the existing methods.

[0017] 2. The metal-free synthesis method of 9,10-bis[N-(2-naphthyl)anilino]anthracene uses industrial chemicals anthracene and 2-naphthylaniline as raw materials, which are cheap and easily available, avoids pre-modification, improves the utilization rate of molecules, and reduces the three wastes. In addition, this method does not require catalysts, no metal participation, and no precious metal catalysis, effectively avoiding late metal residues. The oxidants, additives, and solvents used are less harmful, the reaction conditions are mild, the post-processing is simple, and the three wastes are small. The obtained product has excellent purity and considerable yield, which is in line with the sustainable development direction of green chemistry. DETAILED DESCRIPTION

[0018] A metal-free catalytic synthesis method of 9,10-bis[N-(2-naphthyl)anilino]anthracene, characterized by comprising the following steps: adding refined anthracene, N-phenyl-2-naphthylamine, an oxidant, an additive, and a solvent into a reaction vessel under an oxidizing atmosphere (which may be air or oxygen, etc.), wherein the oxidant is selected from at least one of 30% hydrogen peroxide, sodium persulfate, and oxygen, the additive is selected from at least one of potassium phosphate, pivalic acid, and 1,8-diazabicyclo[5.4.0]undec-7-ene, and the solvent is selected from xylene, 1,2-dimethylbenzene, and the like. At least one of ethyl chloride and ethanol, preferably, the ratio of anthracene, N-phenyl-2-naphthylamine, oxidant, additive and solvent can be 1 mol: (2-2.2 mol): (3-3.3 mol): (2-2.2 mol): (1.5-2 L); after the addition is completed, the temperature is raised to reflux or 80°C to 120°C, and the reaction is carried out for 8-15 hours. After the reaction is completed, the temperature is lowered to room temperature and the crude product is directly filtered to obtain 9,10-bis[N-(2-naphthyl)anilino]anthracene.

[0019] The principle of the above-mentioned synthesis method is that, in an oxidizing atmosphere, with the assistance of additives, the charge-rich anthracene is oxidized by an oxidant to obtain a radical cation, and N-phenyl-2-naphthylamine realizes nucleophilic addition to complete the CN bond construction, and further oxidation and deprotonation (with the assistance of additives) obtain an anthracene precursor modified with 9-amino acid. The solubility is greatly improved compared to anthracene. Due to the modification of amines, the charge-rich system is further improved, so that the above-mentioned amine modification process can occur again, and finally the anthracene precursor modified with diamines at the 9,10 positions is obtained.

[0020] In a preferred embodiment, stirring is performed while the temperature is increased and the rotation speed is adjusted to 300 rpm.

[0021] The above separation can be performed by adding water and n-hexane for elution, and the purity of the product obtained by HPLC is >99%; it can also be performed by adding water and ethyl acetate for extraction, and the organic layer is desolvated to obtain a crude product by column chromatography, and the purity of the product obtained by HPLC is >99.5%.

[0022] Example 1

[0023] Under air atmosphere conditions, 17.8 g of anthracene (Mr = 178.2, 99.0%, 0.1 mol), 43.9 g of N-phenyl-2-naphthylamine (Mr = 219.3, 99.9%, 0.2 mol), and 63.6 g of K3PO4 (Mr = 212.3, 99%, 0.3 mol) were added into a 250 mL reaction flask. Then 150 mL of xylene was added, and subsequently 30 mL of hydrogen peroxide (Mr = 34, 30%, 0.3 mol) was slowly added dropwise to the system while maintaining the temperature below 40 °C. After the feeding was completed, the temperature was raised to 80 °C and the reaction was carried out for 10 h. The reaction was monitored by thin-layer chromatography (TLC). After the reaction ended, the insoluble substances were filtered off and the xylene was recovered by distillation. The residue was added with water and extracted with ethyl acetate. The organic layer was desolvated to obtain the crude product, and 32.5 g of 9,10-bis[N-(2-naphthyl)anilino]anthracene was obtained by column chromatography, with a yield of 53.1% and a purity > 99.5%.

[0024] Example 2

[0025] Under oxygen atmosphere conditions, 17.8 g of anthracene (Mr = 178.2, 99.0%, 0.1 mol), 48.25 g of N-phenyl-2-naphthylamine (Mr = 219.3, 99.9%, 0.22 mol), and 20.4 g of pivalic acid (Mr = 102.1, 99%, 0.2 mol) were added into a 250 mL reaction flask. Then 150 mL of ethanol was added, and subsequently 30 mL of hydrogen peroxide (Mr = 34, 30%, 0.3 mol) was slowly added dropwise to the system while maintaining the temperature below 40 °C. After the feeding was completed, the temperature was raised to reflux, the stirring speed was 300 rmp, and the reaction was carried out for 15 h. The reaction was monitored by thin-layer chromatography (TLC). After the reaction ended, the insoluble substances were filtered off and the ethanol was recovered by distillation. The residue was added with water and washed with n-hexane to obtain 55.1 g of 9,10-bis[N-(2-naphthyl)anilino]anthracene, with a yield of 90.1% and a purity > 99%.

[0026] Example 3

[0027] Under air atmosphere conditions, 17.8 g of anthracene (Mr = 178.2, 99.0%, 0.1 mol), 48.3 g of N-phenyl-2-naphthylamine (Mr = 219.3, 99.9%, 0.22 mol), and 30.44 g of DBU (Mr = 152.2, 99%, 0.2 mol) were added into a 250 mL reaction flask. Then 150 mL of DCE was added, and subsequently 30 mL of hydrogen peroxide (Mr = 34, 30%, 0.3 mol) was slowly dropped into the system while maintaining the temperature below 40 °C. After the feeding was completed, the temperature was raised to 80 °C and the reaction was carried out for 12 h. The reaction was monitored by thin-layer chromatography (TLC). After the reaction ended, the insoluble substances were filtered off and DCE was recovered by distillation. The residue was washed with water and n-hexane to obtain 22.8 g of 9,10-bis[N-(2-naphthyl)anilino]anthracene, with a yield of 37.3% and a purity of >99%.

[0028] Example 4

[0029] Under oxygen atmosphere conditions, 17.8 g of anthracene (Mr = 178.2, 99.0%, 0.1 mol), 48.3 g of N-phenyl-2-naphthylamine (Mr = 219.3, 99.9%, 0.22 mol), and 20.4 g of pivalic acid (Mr = 102.1, 99%, 0.2 mol) were added into a 250 mL reaction flask. Then 150 mL of ethanol was added, and subsequently 67.6 potassium persulfate (Mr = 270.3, 99%, 0.25 mol) was slowly added into the system while maintaining the temperature below 40 °C. After the feeding was completed, the temperature was raised to reflux, the rotation speed was 300 rmp, and the reaction was carried out for 15 h. The reaction was monitored by thin-layer chromatography (TLC). After the reaction ended, the insoluble substances were filtered off and ethanol was recovered by distillation. The residue was extracted with water and ethyl acetate, and the organic layer was desolvated to obtain the crude product. After column chromatography, 52.4 g of 9,10-bis[N-(2-naphthyl)anilino]anthracene was obtained, with a yield of 85.6% and a purity of >99.5%.

[0030] Example 5

[0031] Under air atmosphere conditions, 17.8 g of anthracene (Mr = 178.2, 99.0%, 0.1 mol), 48.25 g of N-phenyl-2-naphthylamine (Mr = 219.3, 99.9%, 0.22 mol), and 20.4 g of pivalic acid (Mr = 102.1, 99%, 0.2 mol) were added into a 250 mL reaction flask. Then 150 mL of ethanol was added. After the feeding was completed, the temperature was raised to reflux and the reaction was carried out for 15 h. The reaction was monitored by thin-layer chromatography (TLC). After the reaction ended, the insoluble substances were filtered off and ethanol was recovered by distillation. The residue was washed with water and n-hexane to obtain 23.4 g of 9,10-bis[N-(2-naphthyl)anilino]anthracene, with a yield of 38.2% and a purity of >99%.

[0032] Example 6

[0033] Under air atmosphere conditions, 17.8 g of anthracene (Mr = 178.2, 99.0%, 0.1 mol), 48.3 g of N-phenyl-2-naphthylamine (Mr = 219.3, 99.9%, 0.22 mol), and 30.44 g of DBU (Mr = 152.2, 99%, 0.2 mol) were added into a 250 mL reaction flask. Then 150 mL of ethanol was added, and subsequently 30 mL of hydrogen peroxide (Mr = 34, 30%, 0.3 mol) was slowly dropped into the system while maintaining the temperature below 40 °C. After the feeding was completed, the temperature was raised to 80 °C, the rotation speed was 300 rmp, and the reaction was carried out for 12 h. The reaction was monitored by thin layer chromatography (TLC). After the reaction ended, the insoluble substances were filtered off, DCE was recovered by distillation, the residue was added with water and extracted with ethyl acetate, and the organic layer was desolvated to obtain the crude product. 47.1 g of 9,10-bis[N-(2-naphthyl)anilino]anthracene was obtained by column chromatography, with a yield of 77.3% and a purity > 99.5%.

[0034] Example 7

[0035] Under air atmosphere conditions, 17.8 g of anthracene (Mr = 178.2, 99.0%, 0.1 mol), 48.25 g of N-phenyl-2-naphthylamine (Mr = 219.3, 99.9%, 0.22 mol), and 20.4 g of pivalic acid (Mr = 102.1, 99%, 0.2 mol) were added into a 250 mL reaction flask. Then 150 mL of ethanol was added, and subsequently 30 mL of hydrogen peroxide (Mr = 34, 30%, 0.3 mol) was slowly dropped into the system while maintaining the temperature at 40 - 50 °C. After the feeding was completed, the temperature was raised to reflux, the rotation speed was 300 rmp, and the reaction was carried out for 15 h. The reaction was monitored by thin layer chromatography (TLC). After the reaction ended, the insoluble substances were filtered off, ethanol was recovered by distillation, the residue was added with water and extracted with ethyl acetate, and the organic layer was desolvated to obtain the crude product. 48.7 g of 9,10-bis[N-(2-naphthyl)anilino]anthracene was obtained by column chromatography, with a yield of 79.6% and a purity > 99.5%.

[0036] The above are only the preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope defined by the claims.

[0037] Those not detailed in the present invention are all well-known technologies to those skilled in the art.

Claims

1. A method for synthesizing metal-free catalyzed 9,10-bis[N-(2-naphthyl)anilino]anthracene, characterized in that, It includes the following steps: under an oxidative atmosphere, add anthracene, N-phenyl-2-naphthylamine, an oxidant, an additive, and a solvent into a reaction vessel; after the feeding is completed, raise the temperature for reaction, raise the temperature to reflux or 80 °C to 120 °C, and react for 8 to 15 h. After the reaction is completed, cool the temperature to room temperature and directly filter to obtain a crude product, and 9,10-bis[N-(2-naphthyl)anilino]anthracene can be obtained after separation; The oxidative atmosphere is air or oxygen; The oxidant is selected from at least one of 30% hydrogen peroxide, sodium persulfate, and oxygen; The additive is selected from at least one of potassium phosphate, pivalic acid, and 1,8-diazabicyclo[5.4.0]undec-7-ene; 2. The synthetic method of 9,10-bis[N-(2-naphthyl)anilino]anthracene without metal catalysis according to claim 1, characterized in that: The solvent is selected from at least one of xylene, 1,2-dichloroethane, and ethanol; 3. The synthesis method of 9,10-bis[N-(2-naphthyl)anilino]anthracene without metal catalysis according to claim 1, wherein: The dosage ratio of the anthracene, N-phenyl-2-naphthylamine, oxidant, additive, and solvent is 1 mol:(2 - 2.2 mol):(3 - 3.3 mol):(2 - 2.2 mol):(1.5 - 2 L); 4. A method for synthesizing metal-free catalytic 9,10-bis[N-(2-naphthyl)anilino]anthracene according to claim 1, characterized in that: Stirring is carried out while raising the temperature for reaction, and the rotation speed is adjusted to 300 rpm; 5. A method for synthesizing metal-free catalytic 9,10-bis[N-(2-naphthyl)anilino]anthracene according to any one of claims 1 to 4, characterized in that: The separation is carried out by adding water and n-hexane for washing, and the product purity > 99%; 6. A method for synthesizing metal-free catalytic 9,10-bis[N-(2-naphthyl)anilino]anthracene according to any one of claims 1 to 4, characterized in that: The separation is carried out by adding water and ethyl acetate for extraction, and the organic layer is desolvated to obtain a crude product for column chromatography, and the product purity > 99.5%;