2-bromofluorenone prepared by air oxidation and bromination, method and application

Abstract

The invention discloses 2-bromofluorenone prepared by air oxidation and bromination as well as a method and application thereof, and belongs to the technical field of preparation of 2-bromofluorenone. According to the method disclosed by the invention, the bromine source, the catalyst, the fluorenone and the water are subjected to the reaction in the air environment to prepare the 2-bromofluorenone, in the whole process, bromine, hydrogen bromide and air which are high in volatility do not need to be used as oxidizing agents, water is used as a solvent, toxic reagents are not used, the reaction can be carried out under normal pressure, and the method is environment-friendly, simple to operate and high in yield. And the requirements of large-scale production can be met.

Description

Technical Field

[0001] The invention belongs to the technical field of 2-bromofluorenone preparation, and specifically relates to 2-bromofluorenone prepared by air oxidation bromination, a method and an application thereof. Background Art

[0002] Organic electroluminescent devices have been rapidly developed and gradually industrialized in recent years due to a series of advantages such as self-luminescence, low voltage drive, full curing, wide viewing angle, simple composition and process, etc. The organic layer in the organic electroluminescent device mainly includes hole injection layer, hole transport layer, electron blocking layer, light-emitting layer, etc. The fluorene unit is a rigid planar biphenyl structure with thermal and chemical stability; it has a high quantum yield in the solid film state; it also has high chemical activity and can be derivatized at multiple chemical sites; therefore, fluorene-based materials have very wide applications in the field of electroluminescent materials. 2-Bromofluorenone is one of the most widely used fluorene material intermediates. It can be used as an additive for photoconductive materials and as a raw material for the synthesis of luminescent materials. Its synthesis process and product quality have a great impact on the development of downstream materials and device performance. In addition, 2-bromofluorenone can also be used in the pharmaceutical industry to synthesize anticancer drugs, sympathetic nerve inhibitors and anticonvulsants; in pesticides, it can be used to synthesize herbicides and insecticides; in the dye industry, it can be used to synthesize aromatic diamine dyes; in the classic copying industry, it is used to make photosensitive materials; in the plastics industry, it can be used to synthesize bisphenol products, stabilizers and plasticizers in the polymerization process, and to prepare functional polymer materials. It has a wide range of applications and has broad application prospects, so people have never stopped studying 2-bromofluorenone.

[0003] It is understood that William S et al. used 2-methyl 4-bromobiphenyl as a raw material and prepared 2-bromofluorenone through oxidation, Friedel-Crafts acylation and other reactions; Donahue P et al. used fluorenone as a raw material and reacted it with N-bromosuccinimide (NBS) in methanesulfonic acid to prepare 2-bromofluorenone, with a yield of only 81%; Ryoichi Akaba et al. used 2,4,6-triphenylpyran tetrafluoroborate as a catalyst and dichloromethane as a solvent to oxidize 2-bromofluorene to obtain 2-bromofluorenone, with a yield of 75%; Pei Jian et al. used tetrabutylhydroxylammonium as a phase transfer catalyst and pyridine as a solvent to oxidize 2-bromofluorene with air to obtain 2-bromofluorenone, with a yield of 84%. Obviously, in the above-mentioned preparation methods of 2-bromofluorenone, there are problems such as complex operation, low yield, high cost, difficulty in separating and purifying reactants, and environmental pollution.

[0004] The Chinese patent application with application number CN108530262A discloses that fluorene is mixed with hydrobromic acid, triphenylphosphine dibromide and a catalyst (benzoyl peroxide), heated to reflux for 1-1.5 hours, then cooled to 25-35°C, dibromohydantoin is added, stirred evenly and kept warm for 3-5 hours, the reaction solution is allowed to stand for separation of aqueous phase and organic phase, the organic phase is washed with water, dried, filtered, concentrated and recrystallized in sequence to obtain 2-bromofluorene. This method of brominating fluorene-based materials has a high reaction risk and a high industrial production cost.

[0005] The Chinese patent application with application number CN114409517A discloses a 2-bromofluorenone and a preparation method thereof, wherein dibromohydantoin is used to replace liquid bromine and tetrabutylammonium bromide is used as a catalyst, thereby obtaining 2-bromofluorenone with a higher yield.

[0006] Zhang Yexin et al. reported a method: using fluorenone as a substrate and bromine as a bromine source, 2-fluorenone was obtained by oxidation with hydrogen peroxide. Although the method is simple to operate, it uses bromine. During the reaction, bromine and hydrogen bromide are highly volatile and may cause certain harm to the environment and human body.

[0007] She Yongkang et al. reported a method: mixing fluorenone, a catalyst and water and heating them to 40-60°C, adding dibromohydantoin in batches for reaction, removing bromine and washing to obtain 2-bromofluorenone, wherein the catalyst is tetrabutylammonium bromide. Although the reaction conditions of this method are relatively mild, dibromohydantoin is used as a bromine source. Dibromohydantoin is harmful to the human body and can irritate the eyes, skin and respiratory tract. Inhalation or contact with dibromohydantoin may cause serious health problems. Long-term exposure to dibromohydantoin may also increase the risk of certain types of cancer.

[0008] Wang Yong et al. reported a method: mixing fluorenone and a phase transfer catalyst with an aqueous solution of ammonium bromide, then heating to 40-95°C, and adding the solution in batches to potassium bromate to obtain 2-bromofluorenone, wherein the phase transfer catalyst is a quaternary ammonium salt compound. Although the reaction conditions of this method are simple, the reaction process is cumbersome, and the amount of batch addition is difficult to control, which is not conducive to large-scale production.

[0009] Zhang Zhao et al. reported a method: add measured fluorenone and water to the reactor, heat to 75°C, start to add bromine, control the system temperature to 75-90°C, react for 3-6 hours; cool, absorb excess bromine with saturated sodium bisulfite solution, filter, wash with water, recrystallize the crude product with ethanol, and dry to obtain the product 2-bromofluorenone. This method uses elemental bromine, which is volatile and highly toxic, which is not conducive to reaction operation, and is prone to leakage and environmental pollution. Summary of the invention

[0010] The purpose of the present invention is to provide a 2-bromofluorenone prepared by air oxidation bromination, a method and an application thereof, so as to solve the technical problems that the existing preparation method pollutes the environment and is complicated in operation, which is not conducive to large-scale production.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions:

[0012] The invention discloses a method for preparing 2-bromofluorenone by air oxidation bromination, comprising the following steps:

[0013] After mixing a bromine source, a catalyst, fluorenone and water, air is introduced to react to obtain a reaction product;

[0014] The reaction product is post-treated to obtain 2-bromofluorenone.

[0015] Furthermore, the bromine source is ferric bromide.

[0016] Furthermore, the catalyst is ferric bromide.

[0017] Furthermore, the usage ratio of the ferric bromide, fluorenone and water is (0.5-3) mol: 1 mol: (2-5) mL.

[0018] Furthermore, the reaction temperature is 50-110° C., and the reaction time is 1-10 h.

[0019] Furthermore, the post-treatment includes phase separation, distillation and purification treatments performed sequentially.

[0020] Furthermore, stirring is performed during the reaction, and the stirring speed is 300-1000 rpm.

[0021] Furthermore, after the reaction is completed, the yield of 2-bromofluorenone is 70% to 85%.

[0022] The invention also discloses 2-bromofluorenone prepared by the preparation method.

[0023] The invention also discloses the application of the 2-bromofluorenone in electroluminescent materials.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The invention discloses a method for preparing 2-bromofluorenone by air oxidation bromination. A bromine source, a catalyst, fluorenone and water are used to react in an air environment to prepare the 2-bromofluorenone. In the whole process, no bromine and hydrogen bromide with strong volatility need to be used. Air is used as an oxidant, water is used as a solvent, no toxic reagent is used, and the reaction can be carried out under normal pressure. The method is environmentally friendly and simple to operate. The method can meet the requirements of large-scale production, and solves the technical problems that the existing preparation method has environmental pollution and complex operation, which is not conducive to large-scale production.

[0026] Furthermore, ferric bromide is used as a bromine source and a strong acid catalyst, and also as an oxidation catalyst, which reduces the volatility of hydrogen bromide, improves the utilization rate of hydrogen bromide, and ensures the safety of the process; after the reaction is completed, the iron oxide and ferric bromide aqueous solution can be directly added to hydrogen bromide to regenerate the ferric bromide solution and enter the next reaction cycle, which is more environmentally friendly. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0028] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0029] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0030] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0031] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0032] The invention provides a method for preparing 2-bromofluorenone by air oxidation bromination, wherein ferric bromide is used as a bromine source and a strong acid catalyst, and also as an oxidation catalyst, and the use of highly volatile bromine and hydrogen bromide is avoided; water is used as a solvent, and normal pressure air is used as an oxidant. The method is safe, efficient, and has good industrial application prospects. The method specifically comprises the following steps:

[0033] Adding fluorenone, ferric bromide and water into a reaction container, and then reacting at a certain reaction temperature for a period of time to obtain a reaction product;

[0034] The obtained reaction product is subjected to phase separation, distillation and purification treatment in sequence to obtain 2-bromofluorenone.

[0035] Preferably, the usage ratio of ferric bromide, fluorenone and water is (0.5-3) mol: (1) mol: (2-5) mL.

[0036] Preferably, the reaction temperature is 50-110° C., and the reaction time is 1-10 h.

[0037] Preferably, stirring is performed during the reaction, and the stirring speed is 300-1000 rpm.

[0038] In the reaction process, ferric bromide can be directly obtained from the reaction system of ferric oxide and hydrobromic acid; after the reaction, the aqueous solution of ferric oxide and ferric bromide can be directly added to hydrogen bromide to regenerate the ferric bromide solution and enter the next reaction cycle; using ferric bromide as a catalyst and bromine source reduces the volatility of hydrogen bromide, improves the utilization rate of hydrogen bromide, and ensures the safety of the process. The reaction process uses water as a solvent and atmospheric pressure air as an oxidant. It is safe, efficient, and has good industrial application prospects.

[0039] The method of the present invention can prepare 2-bromofluorenone by brominating fluorenone with high selectivity. Ferric bromide, as a catalyst and a bromine source, can be oxidized by air into bromine and ferric oxide for brominating fluorenone, and can also be used as a strong Lewis acid catalyst to catalyze the bromination of fluorenone to obtain 2-bromofluorenone. Ferric bromide can be directly obtained from a reaction system of ferric oxide and hydrobromic acid. The remaining ferric oxide and ferric bromide can be reused for the next preparation of 2-bromofluorenone. Using ferric bromide as a catalyst and a bromine source reduces the volatility of hydrogen bromide, improves the utilization rate of hydrogen bromide, and also ensures the safety of the process. The reaction process uses water as a solvent and atmospheric pressure air as an oxidant, is safe and efficient, and has good industrial application prospects.

[0040] The principle of the present invention is shown in the following reaction formula:

[0041]

[0042] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0043] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0044] Example 1

[0045] A method for preparing 2-bromofluorenone by air oxidation bromination comprises the following steps:

[0046] 180 g (1 mol) of fluorenone, 444 g (1.5 mol) of ferric bromide and 1000 mL of water were added to the reaction container respectively, and an air balloon was connected. The reaction was stirred at 80°C for 5 hours. After the reaction was completed, the temperature was cooled to room temperature, and a yellow solid was obtained after filtration, washing the filter cake with water and drying. GC analysis showed 161 g of 2-bromo-9-fluorenone, with a yield of 70%.

[0047] Example 2

[0048] A method for preparing 2-bromofluorenone by air oxidation bromination comprises the following steps:

[0049] 180 g (1 mol) of anthracene, 444 g (1.5 mol) of ferric bromide and 1000 mL of water were added to the reaction container respectively, and an air balloon was connected. The reaction was stirred at 80°C for 7 hours. After the reaction was completed, the temperature was cooled to room temperature, and a yellow solid was obtained after filtration, washing the filter cake with water and drying. GC analysis showed 171 g of 2-bromo-9-anthracene, with a yield of 74%.

[0050] Example 3

[0051] A method for preparing 2-bromofluorenone by air oxidation bromination comprises the following steps:

[0052] 180 g (1 mol) of fluorenone, 444 g (1.5 mol) of ferric bromide and 1000 mL of water were added to the reaction container respectively, and an air balloon was connected. The reaction was stirred at 80°C for 10 hours. After the reaction was completed, the temperature was cooled to room temperature, and a yellow solid was obtained after filtration, washing the filter cake with water and drying. GC analysis showed 161 g of 2-bromo-9-fluorenone, with a yield of 70%.

[0053] Example 4

[0054] A method for preparing 2-bromofluorenone by air oxidation bromination comprises the following steps:

[0055] 180 g (1 mol) of fluorenone, 444 g (1.5 mol) of ferric bromide and 1000 ml of water were added to the reaction container respectively, and an air balloon was connected. The reaction was stirred at 100°C for 5 hours. After the reaction was completed, the temperature was cooled to room temperature, and a yellow solid was obtained after filtration, washing the filter cake with water and drying. GC analysis showed 174 g of 2-bromo-9-fluorenone, with a yield of 75%.

[0056] Example 5

[0057] A method for preparing 2-bromofluorenone by air oxidation bromination comprises the following steps:

[0058] 180 g (1 mol) of fluorenone, 444 g (1.5 mol) of ferric bromide and 1000 mL of water were added to the reaction container respectively, and an air balloon was connected. The reaction was stirred at 110°C for 5 hours. After the reaction was completed, the temperature was cooled to room temperature, and a yellow solid was obtained after filtration, washing the filter cake with water and drying. GC analysis showed 186 g of 2-bromo-9-fluorenone, with a yield of 80%.

[0059] Example 6

[0060] A method for preparing 2-bromofluorenone by air oxidation bromination comprises the following steps:

[0061] 180 g (1 mol) of anthracene, 592 g (2 mol) of ferric bromide and 1000 mL of water were added to the reaction vessel respectively, and an air balloon was connected. The reaction was stirred at 80°C for 5 h. After the reaction was completed, the temperature was cooled to room temperature, and a yellow solid was obtained after filtration, washing the filter cake with water and drying. GC analysis showed 184 g of 2-bromo-9-anthracene, with a yield of 79%.

[0062] Example 7

[0063] A method for preparing 2-bromofluorenone by air oxidation bromination comprises the following steps:

[0064] 180 g (1 mol) of anthracene, 888 g (3 mol) of ferric bromide and 1000 mL of water were added to the reaction container respectively, and an air balloon was connected. The reaction was stirred at 80°C for 5 hours. After the reaction was completed, the temperature was cooled to room temperature, and a yellow solid was obtained after filtration, washing the filter cake with water and drying. GC analysis showed 189 g of 2-bromo-9-anthracene, with a yield of 81%.

[0065] Comparative Example 8 (the catalyst addition method is changed, and iron oxide and hydrobromic acid are added, which is equivalent to adding iron bromide. Iron oxide is generated after the reaction, and iron bromide is regenerated with hydrogen bromide)

[0066] A method for preparing 2-bromofluorenone by air oxidation bromination comprises the following steps:

[0067] 180 g (1 mol) of fluorenone, 240 g (1.5 mol) of ferric oxide, 760 g (4.5 mol) of 48% hydrobromic acid, and 600 mL of water were added to the reaction vessel, and air was slowly bubbled into the reactor. The reaction was stirred at 110°C for 10 h. After the reaction was completed, the temperature was cooled to room temperature. After filtration, the filter cake was washed with water and dried to obtain 150 g of yellow solid 2-bromo-9-fluorenone with a yield of 72%.

[0068] Example 9

[0069] A method for preparing 2-bromofluorenone by air oxidation bromination comprises the following steps:

[0070] 180 g (1 mol) of fluorenone, 888 g (3 mol) of ferric bromide and 1000 mL of water were added to the reaction vessel respectively, air was bubbled slowly into the reactor, and the reaction was stirred at 110°C for 10 hours. After the reaction was completed, the temperature was cooled to room temperature, and a yellow solid was obtained after filtration, washing the filter cake with water and drying. GC analysis showed 194 g of 2-bromo-9-fluorenone, with a yield of 85%.

[0071] Example 10

[0072] After the reaction of Example 9 is completed, the organic matter on the upper layer of the aqueous solution is separated, and 169 g (1 mol) of 48% hydrobromic acid is added to the aqueous phase, the iron catalyst is reused, and 180 g (1 mol) of fluorenone is added again. The reaction is stirred at 110° C. for 10 h. After the reaction is completed, the temperature is cooled to room temperature, and 2-bromo-9-fluorenone is obtained by filtration, washing the filter cake with water and drying it. A yellow solid 2-bromo-9-fluorenone is obtained.

[0073] Table 1 shows the data of the number of catalyst recycling times and the yield of 2-bromofluorenone during the preparation process. It can be seen from the table that the catalyst can be recycled and reused many times without a significant decrease in catalyst activity.

[0074] Table 1 Catalyst recovery times and 2-bromofluorenone yield data

[0075]

[0076]

[0077] The present invention uses ferric bromide as a bromine source and a strong acid catalyst, and also as an oxidation catalyst, avoiding the use of highly volatile bromine and hydrogen bromide. The specific steps are: adding fluorenone, ferric bromide, and water into a reaction container and reacting at a certain reaction temperature for a period of time, and then phase separation, distillation, and purification can obtain the product 2-bromofluorenone. Ferric bromide, as a catalyst and a bromine source, can be oxidized by air into bromine and ferric oxide for bromination of fluorenone, and can also be used as a strong Lewis acid catalyst to catalyze the bromination of fluorenone to obtain 2-bromofluorenone. Ferric bromide can be directly obtained from a reaction system of ferric oxide and hydrobromic acid; after the reaction is completed, an aqueous solution of ferric oxide and ferric bromide can be directly added to hydrogen bromide to regenerate an ferric bromide solution and enter the next reaction cycle; using ferric bromide as a catalyst and a bromine source reduces the volatility of hydrogen bromide, improves the utilization rate of hydrogen bromide, and also ensures the safety of the process. The reaction process uses water as a solvent and atmospheric pressure air as an oxidant, is safe and efficient, and has a good industrial application prospect.

[0078] This method uses air as an oxidant, without the need for strong oxidants such as hydrogen peroxide or chlorine, and has lower environmental pollution and risks, meeting the requirements of green chemistry; air oxidation reactions are usually milder, avoiding toxic or dangerous byproducts that may be produced in traditional oxidation processes, and improving the safety and environmental friendliness of the reaction; ferric bromide, as a bromine source and catalyst, plays a dual role in the reaction, reducing the reaction steps and costs. Ferric bromide is a common and relatively cheap chemical reagent that can provide good reaction effects, while also facilitating the control of reaction conditions and simplifying reaction operations; ferric bromide as a catalyst helps improve the selectivity and efficiency of the reaction, avoids the use of excessive bromine sources in traditional bromination methods, and reduces unnecessary byproducts in the reaction; using ferric bromide as a bromine source, strong acid catalyst and oxidation catalyst has significant advantages. First, ferric bromide can play multiple roles in the reaction, both as an oxidant to provide a bromine source and to accelerate the reaction through catalysis. This multifunctional catalytic effect reduces the demand for other chemical reagents, simplifies the process flow, and reduces the reaction cost. In addition, the oxidation reaction catalyzed by ferric bromide is milder than the traditional method, avoiding the side reactions that may be caused by high reaction temperatures, thereby improving the selectivity of the reaction and the purity of the product. Hydrogen bromide is a volatile chemical with a pungent odor. The volatility of hydrogen bromide in the traditional bromination reaction is relatively high, which may cause environmental pollution and safety hazards. However, the use of ferric bromide as a catalyst can effectively reduce the volatility of hydrogen bromide, promote more efficient use of hydrogen bromide, and improve the safety of the reaction. After hydrogen bromide reacts with ferric bromide in an aqueous solution, the generated hydrogen bromide gas will be fixed in the reaction system, reducing the possibility of volatilization and reducing the risk of operators being exposed to harmful gases. In addition, after the reaction is completed, the aqueous solution of iron oxide and ferric bromide can directly react with hydrogen bromide to generate a new ferric bromide solution. This recycling process not only saves raw material costs, but also greatly reduces the generation of waste, improves the utilization efficiency of resources, and makes the entire process more environmentally friendly. This closed-loop reaction system effectively reduces waste emissions and chemical pollution in production, and is a sustainable process that complies with the principles of green chemistry.

[0079] At the same time, the reaction temperature is controlled at 50-110°C and the reaction time is between 1-10 hours, which means that the reaction is carried out at a moderate temperature, which can effectively control the reaction rate and reduce the occurrence of side reactions; the mild reaction conditions reduce energy consumption and can reduce the generation of harmful substances or high-temperature decomposition caused by high temperature, thereby improving the quality and yield of the product; 2-bromofluorenone is an important intermediate of electroluminescent materials, and its application in electronic and optoelectronic devices such as OLED and LED is very extensive, so this method has great market potential, and the implementation of this technical solution can meet the needs of industrial production, especially in the field of electronic materials, and has significant economic benefits.

[0080] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing 2-bromofluorenone by air oxidation bromination, characterized in that: The following steps are involved: After mixing a bromine source, a catalyst, fluorenone and water, air is introduced to react to obtain a reaction product; The reaction product is post-treated to obtain 2-bromofluorenone.

2. The method for preparing 2-bromofluorenone by air oxidation bromination according to claim 1, characterized in that: The bromine source is ferric bromide.

3. The method for preparing 2-bromofluorenone by air oxidation bromination according to claim 2, characterized in that: The catalyst is ferric bromide.

4. The method for preparing 2-bromofluorenone by air oxidation bromination according to claim 3, characterized in that: The dosage ratio of the ferric bromide, fluorenone and water is (0.5-3) mol: 1 mol: (2-5) mL.

5. The method for preparing 2-bromofluorenone by air oxidation bromination according to claim 1, characterized in that: The reaction temperature is 50-110° C., and the reaction time is 1-10 h.

6. The method for preparing 2-bromofluorenone by air oxidation bromination according to claim 1, characterized in that: The post-treatment includes phase separation, distillation and purification treatments performed sequentially.

7. The method for preparing 2-bromofluorenone by air oxidation bromination according to claim 1, characterized in that: Stirring is performed during the reaction, and the stirring speed is 300-1000 rpm.

8. The method for preparing 2-bromofluorenone by air oxidation bromination according to claim 1, characterized in that: After the reaction is completed, the yield of 2-bromofluorenone is 70% to 85%.

9. A 2-bromofluorenone, characterized in that The preparation method is described in any one of claims 1 to 8.

10. Use of the 2-bromofluorenone according to claim 9 in electroluminescent materials.

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