A method for synthesizing an optoelectronic material intermediate, 1-bromodibenzofuran

Abstract

The application discloses a synthesis method of photoelectric material intermediate 1-bromodibenzofuran. ， The synthesis method uses m-bromophenyl methyl ether as a starting material, adds diisopropyl lithium and o-fluoro nitrobenzene to obtain 2-bromo-6-methoxy-2 The intermediate 1-bromodibenzofuran is synthesized by using the application, and from the starting material to the final product, purification is not needed in the middle, loss of intermediate products is reduced, the product yield is high, and the comprehensive yield is more than 78%. In the synthesis method, the raw material is simple and easy to obtain, no strong pollution material is used, the post-treatment operation is simple and easy to implement, and the method is suitable for industrial production.

Description

I. TECHNICAL FIELD

[0001] The present application belongs to the technical field of synthesis of photoelectric material intermediates, and particularly relates to a synthesis method of a photoelectric material intermediate 1-bromodibenzofuran. II. BACKGROUND

[0002] The main problem of organic electroluminescent devices (OLED) is that the service life and efficiency of the materials cannot meet the practical requirements. Therefore, the research on the synthesis of organic light-emitting materials with high fluorescence electron yield, high thermal stability and easy carrier transport is an important direction of current OLED research. According to the current research, the oxofluorene structure can be used as a light-emitting material applied in organic electroluminescent devices, so that the organic electroluminescent devices have high thermal stability and light-emitting efficiency.

[0003] At present, 1-bromodibenzofuran with an oxofluorene structure as a photoelectric material intermediate has also been reported in related patent documents. For example: 1. 2-Fluoro-6-bromoiodebenzene is used as a raw material, a Suzuki coupling is performed, a demethylation is performed to form 2-bromo-6-fluoro-2'-hydroxybiphenyl, and then a ring closure is performed to prepare 1-bromodibenzofuran (see WO2015169412 for details). 2. The invention patent CN109928945 discloses a 1-bromodibenzofuran and a synthesis method thereof. The method utilizes m-fluorobromobenzene, trimethyl borate and diisopropyl lithium to generate 2-bromo-6-fluorobenzene boronic acid through a low-temperature reaction, the generated 2-bromo-6-fluorobenzene boronic acid and potassium difluorohydride generate a salt reaction to generate 2-bromo-6-fluoro-phenyl potassium trifluoroborate; the generated 2-bromo-6-fluoro-phenyl potassium trifluoroborate and o-bromophenol undergo a coupling reaction to generate 2'-bromo-6'-fluorobiphenyl-2-ol, and the generated 2'-bromo-6'-fluorobiphenyl-2-ol undergoes a ring closure reaction to generate 1-bromodibenzofuran. 3. The invention patent CN115677637 discloses a simple preparation method of 1-bromodibenzofuran. The method uses a plurality of o-dihalides as starting materials to prepare 1-bromodibenzofuran through 3-step reactions. The o-dihalides have a relatively low price, and the o-dihalides and 1,3-cyclohexanedione undergo an intermolecular and intramolecular Ullmann reaction to obtain 3,4-dihydrodibenzo[b,d]furan-1(2H)-one, and then the 3,4-dihydrodibenzo[b,d]furan-1(2H)-one is oxidized into dibenzo[b,d]furan-1-ol by DDQ. Finally, the compound reacts with phosphorus tribromide to generate the target product 1-bromodibenzofuran.

[0004] In the above-mentioned existing synthesis methods, the first method introduces a heavy metal catalyst in the synthesis of 2-bromo-6-fluoro-2'-hydroxybiphenyl, which is not only expensive but also affects the performance of the photoelectric material due to trace residues; the second method has a low route yield and a relatively high cost, and is not suitable for industrial production. The third method has a slow reaction progress, a long reaction time, and a dry column treatment method, and uses dangerous and polluting materials such as DDQ and phosphorus tribromide in the later stage. In summary, the existing synthesis methods are not convenient for industrial production. Therefore, a new synthesis method of 1-bromodibenzofuran suitable for industrial production is needed. III. SUMMARY

[0005] The technical problem to be solved by the present application is that, according to the current status and problems of the existing synthesis method of the photoelectric material intermediate 1-bromodibenzofuran, the present application provides a new synthesis method of 1-bromodibenzofuran with high yield, low cost and suitable for industrial production.

[0006] To solve the above-mentioned problems, the technical scheme adopted by the present application is as follows:

[0007] The present application provides a synthesis method of the photoelectric material intermediate 1-bromodibenzofuran, which comprises the following steps:

[0008] a. Dissolve m-bromophenyl methyl ether in tetrahydrofuran, and drop lithium diisopropylamide at a temperature below -40℃. After the drop is completed, keep the temperature for 20-40 min. Then drop o-fluoronitrobenzene, and keep the temperature for 20-40 min after the drop is completed. After TLC detection shows no raw material, naturally warm to room temperature, drop dilute hydrochloric acid to adjust the pH value to 6-7, then sequentially perform liquid separation, water layer extraction, organic layer combination, anhydrous magnesium sulfate drying, and rotary evaporation to obtain 2-bromo-6-methoxy-2'-nitrobiphenyl TM1;

[0009] b. Dissolve the obtained TM1 in ethanol, and after dissolution, add reduced iron powder and warm to 55-60℃. Then drop glacial acetic acid, and keep the temperature for 3-4 h after the drop is completed. After keeping the temperature, filter with diatomite and rotary evaporation to obtain 2-bromo-6-methoxy-2'-nitrobiphenyl TM2;

[0010] c. Dissolve the obtained TM2 in tetrahydrofuran, and after dissolution, add 40% sulfuric acid at room temperature. Then drop sodium nitrite aqueous solution, keep the temperature for 0.5-1 h after the drop, and then warm to room temperature for stirring reaction for 2-3 h. After HPGC detection shows no raw material, sequentially perform layer separation, ethyl acetate extraction, saturated brine washing to neutral, drying, rotary evaporation, cyclohexane hot solution filtration, and rotary evaporation dispersion purification to obtain the product 1-bromodibenzofuran.

[0011] According to the synthesis method of the photoelectric material intermediate 1-bromodibenzofuran, the molar ratio of the m-bromophenyl methyl ether, diisopropyl amino lithium and o-fluorine nitrobenzene added in step a is 1:1.1-1.3:1.05-1.2.

[0012] According to the synthesis method of the photoelectric material intermediate 1-bromodibenzofuran, when the m-bromophenyl methyl ether is dissolved in tetrahydrofuran in step a, the mass-volume ratio between the two is 1:3-6; and the mass percentage concentration of the dilute hydrochloric acid is 10-30%.

[0013] According to the synthesis method of the photoelectric material intermediate 1-bromodibenzofuran, the molar ratio of the TM1, the reduced iron powder and the glacial acetic acid added in step b is 1:3-4:5-8.

[0014] According to the synthesis method of the photoelectric material intermediate 1-bromodibenzofuran, when the TM1 is dissolved in ethanol in step b, the mass-volume ratio of the TM1 and the ethanol added is 1:3-6.

[0015] According to the synthesis method of the photoelectric material intermediate 1-bromodibenzofuran, the molar ratio of the TM2 and the sodium nitrite added in step c is 1:1.2-1.25; and the mass ratio of the TM2 and the sulfuric acid added is 1:4-5.

[0016] According to the synthesis method of the photoelectric material intermediate 1-bromodibenzofuran, when the TM2 is dissolved in tetrahydrofuran in step c, the mass-volume ratio of the TM2 and the tetrahydrofuran added is 1:4-8.

[0017] According to the synthesis method of the photoelectric material intermediate 1-bromodibenzofuran, the mass percentage concentration of the aqueous sodium nitrite solution in step c is 30-40%.

[0018] The synthesis route of the photoelectric material intermediate 1-bromodibenzofuran is as follows:

[0019]

[0020] The positive beneficial effects of the present application are as follows:

[0021] 1. The intermediate 1-bromodibenzofuran is synthesized by the method of diazonium salt, which is a new synthesis method.

[0022] 2. The intermediate 1-bromodibenzofuran is synthesized by the method of the present application, and the product yield is high, and the comprehensive yield reaches more than 78%; and the purity of the obtained product reaches about 99.7%.

[0023] 3. The raw materials used in the synthesis method of this invention are simple and readily available, and there is no use of highly polluting materials. The post-processing operation is simple and easy to carry out, making it suitable for industrial production. IV. Description of the attached drawings:

[0024] Figure 1 The 1H NMR spectrum of the compound 1-bromodibenzofuran prepared in Example 1 of this invention.

[0025] Depend on Figure 1 It can be seen that the doublet at chemical shift 8.50 represents one hydrogen atom at carbon position 8, the doublet at chemical shift 7.56-7.58 represents one hydrogen atom at carbon position 2, the peak at chemical shift 7.48-7.53 represents three hydrogen atom groups at carbon positions 3, 4, and 5, the triplet at chemical shift 7.37-7.41 represents one hydrogen atom at carbon position 6, and the triplet at chemical shift 7.28-7.32 represents one hydrogen atom at carbon position 7. This indicates that the compound prepared in this invention is 1-bromodibenzofuran.

[0026] Figure 2 HPLC spectrum of 1-bromodibenzofuran synthesized in Example 1 of this invention. V. Detailed Implementation Methods:

[0027] The present invention will be further illustrated below with reference to the embodiments, but this does not limit the scope of protection of the technical solution of the present invention.

[0028] Example 1:

[0029] The method for synthesizing 1-bromodibenzofuran, an intermediate for optoelectronic materials, according to the present invention, comprises the following detailed steps:

[0030] a. Add 28.06 g (0.15 mol) of m-bromoanisole and 140 mL of tetrahydrofuran to the reactor, stir to dissolve, and after uniform dissolution, purge with nitrogen for 5 min. Then, lower the reaction system temperature to -40℃ using liquid nitrogen and an anhydrous ethanol bath. Control the reaction system temperature at -50 to -40℃ and add 90 mL (0.18 mol) of 2M diisopropylaminolithium dropwise. After the addition is complete, maintain the temperature for 30 min. Then, continue to add 23.28 g (0.165 mol) of 2M o-fluoronitrobenzene dropwise. After adding mol of the solution, the mixture was kept warm for 30 min. TLC showed no raw material, and the mixture was then naturally heated to room temperature. At room temperature, 11% hydrochloric acid was added dropwise to adjust the pH to 6. The mixture was then separated into liquid and liquid layers. The aqueous layer was extracted twice with ethyl acetate (30 mL each time). The organic layers were combined and dried with anhydrous magnesium sulfate for 1 h. The mixture was then filtered and rotary evaporated to obtain 51 g of 2-bromo-6-methoxy-2'-nitrobiphenyl (TM1), with a yield of 100% and a purity of 97%.

[0031] b, the obtained 51 g of TM1 (0.15 mol, purity 97%) was dissolved in 200 mL of ethanol, and then 43.98 g (0.525 mol) of reduced iron powder was added, and the temperature was raised to 60°C, and then 54.05 g (0.90 mol) of glacial acetic acid was added dropwise, and after the dropwise addition was completed, the solution was kept for 3 h; no raw material was detected by TLC, and then the solution was filtered through diatomite, and rotary evaporation was performed to constant weight, to obtain 2-bromo-6-methoxy-2'-aminobiphenyl (TM2) 42.03 g, with a yield of 100% and a purity of 97%;

[0032] c, the obtained 42.03 g of TM2 (0.15 mol, purity 97%) was dissolved in 200 mL of tetrahydrofuran, and then 168 g of 40% sulfuric acid was added under nitrogen protection and at room temperature, and the solution was stirred uniformly, and then the temperature was lowered to 0°C; 0-10°C was controlled, and then sodium nitrite aqueous solution (12.42 g, 0.18 mol of sodium nitrite and 24.84 g of water were added to the solution) was added dropwise, and after the dropwise addition was completed, the solution was kept for 1 h, and then the temperature was raised to room temperature for stirring reaction for 2 h; no raw material was detected by HPGC, and then the solution was sequentially layered, extracted with ethyl acetate, washed with saturated brine to neutral, dried, rotary evaporated, hot-solubilized with cyclohexane, filtered, and rotary evaporated and dispersed for purification, to obtain product intermediate 1-bromodibenzofuran 28.92 g, with a purity of 99.7% and a yield of 78.02% (the nuclear magnetic resonance spectrum of the obtained product and the HPLC spectrum are shown in the following figures). Figure 1 and the following figures). Figure 2

[0033] Example 2:

[0034] The synthesis method of the photoelectric material intermediate 1-bromodibenzofuran of the present application is as follows:

[0035] a, 28.06 g (0.15 mol) of m-bromoanisole and 140 mL of tetrahydrofuran were put into a reactor, and the solution was stirred and dissolved, and after the solution was uniformly dissolved, nitrogen was introduced for 5 min, and then the temperature of the reaction system was lowered to -40°C by liquid nitrogen and anhydrous ethanol bath, 2M diisopropylamine lithium 97.5 mL (0.195 mol) was added dropwise under the condition that the temperature of the reaction system was controlled at -50 to -40°C, and after the dropwise addition was completed, the solution was kept for 25 min; then 2M o-fluoro nitrobenzene 25.38 g (0.18 mol) was continuously added dropwise, and after the dropwise addition was completed, the solution was kept for 30 min; no raw material was detected by TLC, and then the pH value was adjusted to 6 by adding 11% dilute hydrochloric acid at room temperature, and then the solution was sequentially layered, the water layer was separated, the water layer was extracted with ethyl acetate twice (30 mL each time), the organic layers were combined, and the organic layer was dried with anhydrous magnesium sulfate for 1 h, and then the solution was filtered and rotary evaporated, to obtain 2-bromo-6-methoxy-2'-nitrobiphenyl (TM1) 53 g, with a yield of 100% and a purity of 96.8%; ​

[0036] b, the resulting 53 g TM1 (0.15 mol, purity 96.8%) was dissolved with 200 mL of ethanol, after dissolution, 37.70 g of reduced iron powder (0.45 mol) was added, the temperature was raised to 58°C, then 45.04 g of glacial acetic acid (0.75 mol) was added dropwise, after dropping, it was incubated for 4 h; TLC detection showed no raw material, then it was filtered with diatomite, rotary evaporation to constant weight, 2-bromo-6-methoxy-2'-aminobiphenyl (TM2) 42.12 g was obtained, the yield was 100%, and the purity was 96.3%;

[0037] c, the resulting 42.12 g TM2 (0.15 mol, purity 96.3%) was dissolved with 200 mL of tetrahydrofuran, after dissolution, 168 g of 40% sulfuric acid was added under nitrogen protection and at room temperature, and stirred uniformly, then the temperature was lowered to 0°C; 0-10°C was controlled, then sodium nitrite aqueous solution (12.42 g, 0.18 mol of sodium nitrite and 24.84 g of water were added to the solution) was added dropwise, after dropping, it was incubated for 1 h, then the temperature was raised to room temperature and stirred for 2 h; HPGC detection showed no raw material, then it was sequentially layered, extracted with ethyl acetate, washed with saturated brine to neutral, dried, rotary evaporation, hot filtration with cyclohexane, rotary evaporation and dispersion purification, 29.32 g of product intermediate 1-bromodibenzofuran was obtained, the purity was 99.49%, and the yield was 79.10%.

Claims

1. A method for synthesizing 1-bromodibenzofuran, an intermediate in optoelectronic materials, characterized in that, The synthesis method includes the following steps: a. Dissolve m-bromoanisole in tetrahydrofuran, cool to below -40°C and add diisopropylaminolithium dropwise. After the addition is complete, keep warm for 20-40 min. Then add o-fluoronitrobenzene dropwise. After the addition is complete, keep warm for 20-40 min. TLC detection shows no raw material. Then naturally warm to room temperature. Add dilute hydrochloric acid dropwise at room temperature to adjust the pH to 6-7. Then perform liquid-liquid extraction, aqueous layer extraction, combine organic layers, dry with anhydrous magnesium sulfate and rotary evaporation to obtain 2-bromo-6-methoxy-2'-nitrobenzene™1. The molar ratio of m-bromoanisole, lithium diisopropylaminodimethylamine, and o-fluoronitrobenzene added is 1:1.1-1.3:1.05-1.2; b. Dissolve the obtained TM1 in ethanol, add reduced iron powder after dissolution, heat to 55-60℃, then add glacial acetic acid dropwise, and keep warm for 3-4 hours after the addition is complete; after keeping warm, TLC detection shows no raw material, then filter with diatomaceous earth and rotary evaporate to obtain 2-bromo-6-methoxy-2'-aminobiphenylTM2. The molar ratio of TM1, reduced iron powder and glacial acetic acid added is 1:3-4:5-8; c. The obtained TM2 was dissolved in tetrahydrofuran. After dissolution, 40% sulfuric acid was added at room temperature, and the temperature was lowered to 0°C. Then, sodium nitrite aqueous solution was added dropwise, and the temperature was maintained for 0.5-1 h. Then, the temperature was raised to room temperature and stirred for 2-3 h. After HPGC detection showed no raw material, the product was then subjected to layering, ethyl acetate extraction, washing with saturated brine until neutral, drying, rotary evaporation, hot dissolution filtration in cyclohexane, and dispersion purification by rotary evaporation to obtain the product 1-bromodibenzofuran. The molar ratio of TM2 to sodium nitrite is 1:1.2 to 1.25; the mass ratio of TM2 to sulfuric acid is 1:4 to 5; and the mass percentage concentration of the sodium nitrite aqueous solution is 30 to 40%.

2. The method for synthesizing 1-bromodibenzofuran, an intermediate in optoelectronic materials according to claim 1, is characterized in that: When m-bromoanisole is dissolved in tetrahydrofuran in step a, the mass-to-volume ratio between the two is 1:3 to 6; the mass percentage concentration of the dilute hydrochloric acid is 10 to 30%.

3. The method for synthesizing 1-bromodibenzofuran, an intermediate in optoelectronic materials according to claim 1, is characterized in that: When TM1 is dissolved in ethanol in step b, the mass-to-volume ratio of TM1 to ethanol is 1:3 to 6.

4. The method for synthesizing 1-bromodibenzofuran, an intermediate in optoelectronic materials according to claim 1, is characterized in that: When TM2 is dissolved in tetrahydrofuran in step c, the mass-to-volume ratio of TM2 to tetrahydrofuran is 1:4 to 8.

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