Synthesis method of deuterated 9-phenyl anthracene boric acid-D8

Abstract

The invention belongs to the technical field of deuterated organic chemical synthesis, and particularly relates to a synthesis method of deuterated 9-phenyl anthraceneboronic acid-D8, which comprises the following steps of: 1, halogenation reaction: reacting 9-phenyl anthracene-D9, bromo-succinimide (NBS) and triethylamine (TEA) in dichloromethane at low temperature to generate an intermediate 9-phenyl-10-bromoanthracene-D8; step 2, carrying out nucleophilic reaction of forming carbon negative by pulling out bromine with strong in a low-temperature environment of-65 DEG C to-70 DEG C, reacting n-butyllithium with the intermediate 9-phenyl-10-bromoanthracene-D8 in 2-methyltetrahydrofuran to generate 9-phenyl anthracene lithium; then triisopropyl borate is added for a boronation reaction, and the 9-phenyl anthracene boric acid-D8 is obtained after hydrochloric acid hydrolysis and purification. The purity of the deuterated 9-phenyl anthracene boric acid-D8 is greater than or equal to 99.8%, the deuteration rate is greater than or equal to 98%, and the deuterated 9-phenyl anthracene boric acid-D8 is suitable for being used as

Description

Technical Field

[0001] This invention belongs to the field of deuterated organic chemical synthesis technology, specifically relating to a method for synthesizing deuterated 9-phenylanthraboric acid-D8. Background Technology

[0002] Deuterated 9-phenylanthracite-D8 is a key intermediate in OLED blue light materials, and its purity and deuteration rate directly affect the luminous efficiency and lifespan of the device.

[0003] The synthesis of common 9-phenylanthracite is similar to that of 9-phenylanthracite-D8, both involving halogenation and strong base bromination to obtain the target product. However, the anthracene structure in the 9-phenylanthracite-D8 molecule contains deuterium atoms, which readily undergo hydrogen-deuterium exchange under altered experimental conditions, reducing the deuteration rate of the anthracene structure and consequently affecting the luminescent lifetime of the fabricated device. Furthermore, if used as an OLED intermediate, the purity of 9-phenylanthracite-D8 directly impacts the ease of post-processing of the final luminescent material and the device's luminescent efficiency; currently, the commercially available purity of 9-phenylanthracite-D8 is only around 99%. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for synthesizing deuterated 9-phenylanthracite-D8, wherein the purity of the prepared deuterated 9-phenylanthracite-D8 is ≥99.8% and the deuteration rate is ≥98%.

[0005] Specifically, the present invention provides the following technical solutions: A method for synthesizing deuterated 9-phenylanthraboric acid-D8 includes the following steps: Step 1, Halogenation reaction: Under low temperature conditions, 9-phenylanthracene-D9, bromosuccinimide (NBS) and triethylamine (TEA) are reacted in dichloromethane to generate intermediate 9-phenyl-10-bromoanthracene-D8; Step 2, nucleophilic reaction of strong base to remove bromine to form carbon negative: In a low temperature environment of -65℃ to -70℃, n-butyllithium is reacted with the intermediate 9-phenyl-10-bromoanthracene-D8 in 2-methyltetrahydrofuran to generate 9-phenylanthracene lithium; then triisopropyl borate is added for borylation reaction, and after hydrolysis with hydrochloric acid and purification, 9-phenylanthraceneboronic acid-D8 is obtained.

[0006] Preferably, the amount of triethylamine added in step one is 10%-45% of the mass of 9-phenylanthracene-D9; more preferably, it is 20%-25%.

[0007] Preferably, the reaction temperature in step one is 0℃-25℃, and the reaction time is 2-3 hours.

[0008] Preferably, the amount of n-butyllithium used in step two is 1.0-1.2 times the molar amount of intermediate 9-phenyl-10-bromoanthracene-D8.

[0009] Preferably, the purification process in step two includes toluene pulping and recrystallization in a mixed solvent of acetone / n-hexane.

[0010] More preferably, in the acetone / n-hexane mixed solvent, the volume ratio of acetone to n-hexane is 1:1~3.

[0011] The beneficial effects of this invention are at least as follows: 1) The present invention provides a method for synthesizing deuterated 9-phenylanthracite-D8, in which an organic base TEA is introduced into the halogenation reaction to neutralize the hydrogen ions released in the reaction, inhibit hydrogen-deuterium exchange, and increase the deuteration rate to over 98%. 2) The present invention provides a method for synthesizing deuterated 9-phenylanthraenoic acid-D8. By optimizing the bromine removal temperature and solvent, using 2-methyltetrahydrofuran as solvent at -65°C to -70°C, and combining n-butyllithium for precise temperature control, the yield is increased to over 76%. 3) The present invention provides a method for synthesizing deuterated 9-phenylanthraboric acid-D8, which improves the purity to over 99.8% through a dual purification process of toluene pulping and acetone / n-hexane recrystallization. Attached Figure Description

[0012] Figure 1 Liquid phase diagram of deuterated 9-phenylanthraboric acid-D8 prepared in Example 1; Figure 2 The 1H NMR spectrum of deuterated 9-phenylanthraboric acid-D8 prepared in Example 1. Detailed Implementation

[0013] This invention provides a method for synthesizing deuterated 9-phenylanthraboric acid-D8, the reaction formula of which is as follows:

[0014] The first step is a halogenation reaction. During this process, the bromine atom in bromosuccinimide (NBS) undergoes a free radical reaction to generate a bromine radical, which then undergoes substitution at the 10 position of 9-phenylanthracene-D9 to generate a deuterium ion (a small amount of hydrogen ions are also generated due to the high reactivity of the deuterium at the 10 position, which readily undergoes hydrogen-deuterium exchange) and the intermediate product 9-phenyl-10-bromoanthracene-D8. The hydrogen generated during the reaction is highly reactive. If it is not consumed quickly, it will undergo hydrogen-deuterium exchange with the deuterated anthracene in 9-phenylanthracene-D9, reducing the deuteration rate of the target product. Therefore, the organic base triethylamine (TEA) is innovatively added to rapidly consume the lethal hydrogen ions, forming triethylamine hydrochloride.

[0015] The second step involves a nucleophilic reaction of strong base desorption of bromine to form a carbon anode. During this process, n-butyllithium reacts with the bromine atom in 9-phenylanthracene-D8 to generate highly reactive 9-phenylanthracene lithium, which is stable only at low temperatures. Because the boron atom in triisopropyl borate (B(OiPr)3) has an empty orbital, it forms a highly reactive intermediate with the boron atom upon contact with 9-phenylanthracene lithium. This intermediate is unstable and loses one molecule of isopropoxy to form isopropanol, yielding 9-phenylanthracene borate-D8, which is then hydrolyzed with hydrochloric acid to 9-phenylanthracene borate-D8. Therefore, controlling the reaction temperature at the time of n-butyllithium addition determines the product yield. Simultaneously, 9-phenyl-10-bromoanthracene-D8 is a solid with low solubility at low temperatures; therefore, balancing the solvent volume during the reaction to ensure production efficiency is a crucial factor.

[0016] 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. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art, or in accordance with the product manual.

[0017] In the following examples, the 9-phenylanthracene-D9 used was sourced from Ningbo Cuiying Chemical Technology Co., Ltd.

[0018] Example 1 In a 500 mL single-necked round-bottom flask equipped with a stirrer, 200 mL of dichloromethane, 10 g of triethylamine, and 45 g of 9-phenylanthracene-D9 were added sequentially. At room temperature, 30 g of bromosuccinimide was added to the round-bottom flask in five batches over two hours. After the addition was complete, the reaction was allowed to proceed for another hour. The solvent was then evaporated by rotary evaporation, and the mixture was dissolved in N,N-dimethylformamide and poured into deionized water to remove succinimide and triethylamine bromate. The mixture was stirred for 30 minutes, filtered, and dried. The yield was 98%.

[0019] 16 g of deuterated 9-phenyl-10-bromoanthracene-D8 and 200 mL of 2-methyltetrahydrofuran were added to a 500 mL three-necked round-bottom flask equipped with nitrogen protection and a cryostat. The anhydrous ethanol in the Dewar flask was cooled to -80°C using liquid nitrogen. The round-bottom flask was then placed in the cooled ethanol solution to maintain the temperature inside the flask between -65°C and -70°C. 19.2 g of n-butyllithium was drawn using a syringe. A mL solution was injected into a round-bottom flask over 1 hour (the amount of n-butyllithium used was 1.05 times the molar amount of the intermediate 9-phenyl-10-bromoanthracene-D8). The mixture was then kept at this temperature and stirred for 1 hour. Triisopropyl borate was then injected into the flask using a syringe. The temperature inside the flask was slowly increased to 10°C. Hydrochloric acid was added to hydrolyze phenyl anthraborate-D8. After stirring for 20 minutes, the aqueous layer was removed, and the organic layer was evaporated to dryness. The mixture was then slurried with toluene. The crude product was recrystallized using a 1:2 volume ratio of acetone / n-hexane to obtain deuterated 9-phenylanthraborate-D8. Yield: 85%, Purity: 99.9%, Deuteration Rate: 98.5%.

[0020] Figure 1 Liquid phase diagram of deuterated 9-phenylanthraboric acid-D8 prepared in Example 1; Figure 2 The 1H NMR spectrum of deuterated 9-phenylanthraboric acid-D8 prepared in Example 1.

[0021] Example 2 In a 500 mL single-necked round-bottom flask equipped with a stirrer, 200 mL of dichloromethane, 5 g of triethylamine, and 45 g of 9-phenylanthracene-D9 were added sequentially. At room temperature, 30 g of bromosuccinimide was added to the round-bottom flask in five batches over two hours. After the addition was complete, the reaction was allowed to proceed for another hour. The solvent was then evaporated by rotary evaporation, and the mixture was dissolved in N,N-dimethylformamide and poured into deionized water to remove succinimide and triethylamine bromate. The mixture was stirred for 30 minutes, filtered, and dried. The yield was 97%.

[0022] 16 g of deuterated 9-phenyl-10-bromoanthracene and 200 mL of 2-methyltetrahydrofuran were added to a 500 mL three-necked round-bottom flask equipped with nitrogen protection and a cryothermometer. The anhydrous ethanol in the Dewar flask was cooled to -80 °C using liquid nitrogen. The round-bottom flask was then placed in the cooled ethanol solution to maintain the temperature inside the flask between -65 °C and -70 °C. 25 mL of n-butyllithium solution was injected into the round-bottom flask using a syringe over 1 hour. The flask was then kept warm and stirred for 1 hour. Triisopropyl borate was then injected into the flask using a syringe. The temperature inside the flask was slowly increased to 10 °C. Hydrochloric acid was then added to hydrolyze phenyl anthraborate-D8. After stirring for 20 min, the aqueous layer was removed, the organic layer was evaporated to dryness, and the mixture was pulped with toluene. The crude product was recrystallized using a 1:2 volume ratio of acetone / n-hexane mixed solvent to obtain deuterated 9-phenyl anthraborate-D8. Yield: 76%, purity: 99.9%, deuteration rate: 98.4%.

[0023] Example 3 In a 500 mL single-necked round-bottom flask equipped with a stirrer, 200 mL of dichloromethane, 20 g of triethylamine, and 45 g of 9-phenylanthracene-D9 were added sequentially. At room temperature, 30 g of bromosuccinimide was added to the round-bottom flask in five batches over two hours. After the addition was complete, the reaction was allowed to proceed for another hour. The solvent was then evaporated by rotary evaporation, and the mixture was dissolved in N,N-dimethylformamide and poured into deionized water to remove succinimide and triethylamine bromate. The mixture was stirred for 30 minutes, filtered, and dried. The yield was 71%.

[0024] 16 g of deuterated 9-phenyl-10-bromoanthracene and 200 mL of 2-methyltetrahydrofuran were added to a 500 mL three-necked round-bottom flask equipped with nitrogen protection and a cryothermometer. The anhydrous ethanol in the Dewar flask was cooled to -80 °C using liquid nitrogen. The round-bottom flask was then placed in the cooled ethanol solution to maintain the temperature inside the flask between -65 °C and -70 °C. 17 mL of n-butyllithium solution was injected into the round-bottom flask using a syringe over 1 hour. The flask was then kept warm and stirred for 1 hour. Triisopropyl borate was then injected into the flask using a syringe. The temperature inside the flask was slowly increased to 10 °C. Hydrochloric acid was then added to hydrolyze phenyl anthraborate-D8. After stirring for 20 min, the aqueous layer was removed, the organic layer was evaporated to dryness, and the mixture was pulped with toluene. The crude product was recrystallized using a 1:3 volume ratio acetone / n-hexane mixed solvent to obtain deuterated 9-phenyl anthraborate-D8. Yield: 81%, purity: 99.8%, deuteration rate: 98.5%.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for synthesizing deuterated 9-phenylanthrabolic acid-D8, characterized in that, Includes the following steps: Step 1, Halogenation reaction: Under low temperature conditions, 9-phenylanthracene-D9, bromosuccinimide and triethylamine are reacted in dichloromethane to generate intermediate 9-phenyl-10-bromoanthracene-D8; Step 2, nucleophilic reaction of strong base to remove bromine to form carbon negative: In a low temperature environment of -65℃ to -70℃, n-butyllithium is reacted with the intermediate 9-phenyl-10-bromoanthracene-D8 in 2-methyltetrahydrofuran to generate 9-phenylanthracene lithium; then triisopropyl borate is added for borylation reaction, and after hydrolysis with hydrochloric acid and purification, 9-phenylanthraceneboronic acid-D8 is obtained.

2. The method for synthesizing deuterated 9-phenylanthraboric acid-D8 according to claim 1, characterized in that, The amount of triethylamine added in step one is 10%-45% of the mass of 9-phenylanthracene-D9.

3. The method for synthesizing deuterated 9-phenylanthraboric acid-D8 according to claim 1 or 2, characterized in that, The reaction temperature in step one is 0℃-25℃, and the reaction time is 2-3 hours.

4. The method for synthesizing deuterated 9-phenylanthraboric acid-D8 according to claim 1 or 2, characterized in that, In step two, the amount of n-butyllithium used is 1.0-1.2 times the molar amount of intermediate 9-phenyl-10-bromoanthracene-D8.

5. The method for synthesizing deuterated 9-phenylanthrabolic acid-D8 according to claim 1 or 2, characterized in that, The purification process in step two includes toluene pulping and recrystallization in a mixed solvent of acetone / n-hexane.

6. The method for synthesizing deuterated 9-phenylanthrabolic acid-D8 according to claim 5, characterized in that, In the acetone / n-hexane mixed solvent, the volume ratio of acetone to n-hexane is 1:1~3.

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