2-bromofluorenones prepared by air oxidation bromination and methods and uses thereof

Abstract

The application discloses a kind of 2-bromofluorenone prepared by air oxidation bromination and method and application, belong to 2-bromofluorenone preparation technical field.The method disclosed in the application, using bromine source, catalyst, fluorenone and water are reacted in air environment to prepare 2-bromofluorenone, the whole process does not need to use strong volatile bromine and hydrogen bromide, air is used as oxidant, with water as solvent, without using toxic reagent, and can be carried out under normal pressure reaction, environment-friendly, simple operation can meet the requirements of large-scale production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of 2-bromofluorenone preparation, and particularly relates to 2-bromofluorenone prepared by air oxidation bromination and a method and application thereof. BACKGROUND

[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 driving, complete solidification, wide viewing angle, simple composition and process. The organic layer in the organic electroluminescent device mainly includes a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer and the like. The fluorene unit is a rigid planar biphenyl structure, has thermal stability and chemical stability, has a high quantum yield in a solid thin film state, and has high chemical activity, so that derivation at multiple chemical sites can be performed. Therefore, the fluorene-based material has a very wide application in the field of electroluminescent materials. 2-bromofluorenone is one of the most widely used intermediates of fluorene materials, which can be used as an additive of a light guide material, and can also be used as a synthetic raw material of a light-emitting material and the like. The synthesis process and product quality of 2-bromofluorenone have a great influence on the development of downstream materials and the performance of devices. In addition, 2-bromofluorenone can be used for synthesizing anticancer drugs, sympathetic nerve inhibitors and antispasmodic agents in the pharmaceutical industry, for synthesizing herbicides and insecticides in pesticides, for synthesizing aromatic diamine dyes in the dye industry, for making photosensitive materials in the classic copying industry, for synthesizing bisphenol products, stabilizers and plasticizers in the polymerization process in the plastic industry, and for preparing functional polymer materials, and has a wide application and broad application prospect. Therefore, the research on 2-bromofluorenone has never stopped.

[0003] It is understood that William S et al. prepared 2-bromofluorenone by oxidation, Friedel-Crafts acylation and the like from 2-methyl 4-bromobiphenyl as a raw material; Donahue P et al. prepared 2-bromofluorenone by reacting fluorenone with N-bromosuccinimide (NBS) in methanesulfonic acid, and the yield was 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, and the yield was 75%; and Pei Jian et al. used tetrabutylammonium hydroxide as a phase transfer catalyst and pyridine as a solvent to oxidize 2-bromofluorene to obtain 2-bromofluorenone, and the yield was 84%. Obviously, in the above-mentioned preparation methods of 2-bromofluorenone, there are problems such as complex operation, low yield, high cost, difficult separation and purification of reactants, and environmental pollution.

[0004] Chinese patent application CN108530262A discloses a method for preparing 2-bromofluorene. The method comprises mixing fluorene with hydrobromic acid, tribenzylphosphonium dibromide and a catalyst (benzoyl peroxide), heating to reflux for 1-1.5 h, then cooling to 25-35 °C, adding dibromohydantoin, stirring uniformly, and then incubating for 3-5 h. The reaction solution is separated into water phase and organic phase. The organic phase is washed with water, and then dried, filtered, concentrated, and recrystallized to obtain 2-bromofluorene. The method for preparing bromofluorene has high risk and high industrial production cost.

[0005] Chinese patent application CN114409517A discloses a method for preparing 2-bromofluorenone. The method uses dibromohydantoin instead of liquid bromine, and uses tetrabutylammonium bromide as a catalyst to obtain 2-bromofluorenone with high yield.

[0006] Zhang Yexin et al. reported a method for preparing 2-bromofluorenone. The method uses fluorenone as a substrate, bromine as a bromine source, and hydrogen peroxide for oxidation. The method is simple to operate, but uses bromine. Bromine and hydrogen bromide have strong volatility during the reaction, which may cause harm to the environment and human body.

[0007] She Yongkang et al. reported a method for preparing 2-bromofluorenone. The method mixes fluorenone, a catalyst, and water, and heats to 40-60 °C. Dibromohydantoin is added in batches for reaction, and then washed to obtain 2-bromofluorenone. The catalyst is tetrabutylammonium bromide. The method has relatively mild reaction conditions, but uses dibromohydantoin as a bromine source. Dibromohydantoin is harmful to the human body, and can cause irritation to the eyes, skin, and respiratory tract. Inhaling or contacting dibromohydantoin can cause serious health problems, and long-term contact with dibromohydantoin can increase the risk of certain types of cancer.

[0008] Wang Yong et al. reported a method for preparing 2-bromofluorenone. The method mixes fluorenone and a phase transfer catalyst with an aqueous solution of ammonium bromide, and then heats to 40-95 °C. The mixture is added to potassium bromate in batches to obtain 2-bromofluorenone. The phase transfer catalyst is a quaternary ammonium salt compound. The method has simple reaction conditions, but the reaction process is complicated. The amount of the batch addition is difficult to control, which is not conducive to large-scale production.

[0009] Zhang Zhao et al. reported a method for preparing 2-bromofluorenone. The method adds a measured amount of fluorenone and water to a reactor, heats to 75 °C, and then starts to add bromine dropwise. The system temperature is controlled at 75-90 °C, and the reaction is carried out for 3-6 h. After cooling, the excess bromine is absorbed with saturated sodium bisulfite solution, filtered, washed with water, and then recrystallized with ethanol. The product 2-bromofluorenone is obtained after drying. The method uses elemental bromine, which has volatility and toxicity, and is not conducive to reaction operation. Moreover, it is easy to leak and pollute the environment. SUMMARY

[0010] The present application aims to provide a 2-bromofluorenone prepared by air oxidation bromination and a method and application thereof, so as to solve the technical problems of the existing preparation method, such as environmental pollution, complex operation, and the like, which are not conducive to large-scale production.

[0011] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions to achieve the above-mentioned purpose:

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

[0013] After the bromine source, the catalyst, the fluorenone and the water are mixed, air is introduced for reaction to obtain a reaction product;

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

[0015] Further, the bromine source is iron bromide.

[0016] Further, the catalyst is iron bromide.

[0017] Further, the use amount ratio of the iron bromide, the fluorenone and the water is (0.5-3) mol: 1 mol: (2-5) mL.

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

[0019] Further, the post-treatment comprises phase separation, distillation and purification treatment in sequence.

[0020] Further, stirring is carried out in the reaction process, and the stirring speed is 300-1000 rpm.

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

[0022] The present application also discloses 2-bromofluorenone prepared by the above preparation method.

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

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

[0025] The application discloses a method for preparing 2-bromofluorenone through air oxidation and bromination, and the method is characterized in that a bromine source, a catalyst, fluorenone and water are used to react in an air environment to prepare 2-bromofluorenone.

[0026] Further, the iron bromide is used as the bromine source and the strong acid catalyst, and also as the oxidation catalyst, so that the volatility of the hydrogen bromide is reduced, the utilization rate of the hydrogen bromide is improved, and the safety of the process is ensured; after the reaction is completed, the iron oxide and the aqueous iron bromide solution can be directly added into the hydrogen bromide to regenerate the iron bromide solution, and then the regenerated iron bromide solution is used in the next reaction cycle, so that the process is more environmentally friendly. DETAILED DESCRIPTION

[0027] To enable those skilled in the art to understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used in the text are of the usual meaning understood by those skilled in the art of the present application, and in case of conflict, the definition in the specification shall prevail.

[0028] Theories or mechanisms described and disclosed herein, whether correct or not, should not be considered limiting the scope of the present application, i.e., the present application can be practiced without relying on any particular theory or mechanism.

[0029] In this text, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents and concentrations, are for the sake of brevity and convenience. Therefore, the description of numerical ranges or percentage ranges should be considered to have covered and specifically disclosed all possible sub-ranges and individual numerical values (including integers and fractions) within the range.

[0030] In this text, unless otherwise specified, "comprising", "including", "containing", "having" or similar words cover the meaning of "consisting of" and "consisting essentially of", for example, "A comprising a" covers the meaning of "A comprising a and other" and "A comprising only a".

[0031] In this text, for the sake of brevity, all possible combinations of the technical features in each embodiment or example are not described. Therefore, as long as the combinations of the technical features do not conflict, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope disclosed in the specification.

[0032] The application 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, so that volatile bromine and hydrogen bromide are avoided; water is used as a solvent, and normal pressure air is used as an oxidant, so that the method is safe and efficient and has a good industrial application prospect, and the method specifically comprises the following steps:

[0033] Fluorenone, ferric bromide and water are added into a reaction container, and then reacted at a certain reaction temperature for a period of time to obtain a reaction product;

[0034] The obtained reaction product is sequentially subjected to phase separation, distillation and purification treatment, so that 2-bromofluorenone is obtained.

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

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

[0037] Preferably, stirring is carried out in the reaction process, and the stirring speed is 300-1000 rpm.

[0038] In the reaction process, the ferric bromide can be directly obtained from an iron oxide and hydrobromic acid reaction system; after the reaction is completed, the iron oxide and the ferric bromide aqueous solution can be directly added into hydrogen bromide to regenerate the ferric bromide solution, so as to enter the next reaction cycle; the ferric bromide is used as the catalyst and the bromine source, so that the volatility of the hydrogen bromide is reduced, the utilization rate of the hydrogen bromide is improved, and the safety of the process is ensured. The reaction process uses water as the solvent and normal pressure air as the oxidant, so that the process is safe and efficient and has a good industrial application prospect.

[0039] The method of the application can selectively brominate fluorenone to prepare 2-bromofluorenone. The ferric bromide is used as the catalyst and the bromine source, can be oxidized by air into bromine and iron oxide for brominating fluorenone, and also as a strong Lewis acid catalyst for catalyzing the bromination of fluorenone to obtain 2-bromofluorenone. The ferric bromide can be directly obtained from an iron oxide and hydrobromic acid reaction system. The residual iron oxide and ferric bromide can be reused for preparing 2-bromofluorenone next time. The ferric bromide is used as the catalyst and the bromine source, so that the volatility of the hydrogen bromide is reduced, the utilization rate of the hydrogen bromide is improved, and the safety of the process is ensured. The reaction process uses water as the solvent and normal pressure air as the oxidant, so that the process is safe and efficient and has a good industrial application prospect.

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

[0041]

[0042] The application will be further described in connection with the following detailed description and examples. It should be understood that these examples are intended to illustrate the application and are not intended to limit the scope of the application. Moreover, it should be understood that variations and modifications of the application can be made based on the teachings of the present application, and that such variations and modifications are to be considered as falling within the scope of the application as defined by the appended claims.

[0043] The following examples use apparatus and equipment that are conventional in the art. The following examples use experimental procedures that are conventional unless otherwise indicated. The following examples use various materials, which are conventional unless otherwise indicated. The following examples use conventional commercial materials, which are conventional in the art, unless otherwise indicated. In the specification and following examples, unless otherwise stated, "%" means weight percent, "parts" means parts by weight, and ratios are by weight.

[0044] Example 1

[0045] A method for preparing 2-bromo fluorenone by air oxidation bromination, comprising the steps of:

[0046] In a reaction vessel, 180 g (1 mol) of fluorenone, 444 g (1.5 mol) of iron bromide, 1000 mL of water were added, 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 decreased to room temperature. After filtration, the filter cake was washed with water and dried to obtain a yellow solid. GC analysis showed that the yield of 2-bromo-9-fluorenone was 161 g, and the yield was 70%.

[0047] Example 2

[0048] A method for preparing 2-bromo fluorenone by air oxidation bromination, comprising the steps of:

[0049] In a reaction vessel, 180 g (1 mol) of fluorenone, 444 g (1.5 mol) of iron bromide, 1000 mL of water were added, 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 decreased to room temperature. After filtration, the filter cake was washed with water and dried to obtain a yellow solid. GC analysis showed that the yield of 2-bromo-9-fluorenone was 161 g, and the yield was 70%.

[0050] Example 3

[0051] A method for preparing 2-bromo fluorenone by air oxidation bromination, comprising the steps of:

[0052] In a reaction vessel, 180 g (1 mol) of fluorenone, 444 g (1.5 mol) of iron bromide, 1000 mL of water were added, 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 decreased to room temperature. After filtration, the filter cake was washed with water and dried to obtain a yellow solid. GC analysis showed that the yield of 2-bromo-9-fluorenone was 161 g, and the yield was 70%.

[0053] Example 4

[0054] A method for preparing 2-bromo fluorenone by air oxidation bromination, comprising the steps of:

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

[0056] Example 5

[0057] A method for preparing 2-bromo fluorenone by air oxidation bromination, comprising the steps of:

[0058] In a reaction vessel, 180 g (1 mol) of fluorenone, 444 g (1.5 mol) of iron bromide, 1000 mL of water were added respectively, and an air balloon was connected. The reaction was stirred at 100 °C for 5 h. After the reaction was completed, it was cooled to room temperature. After filtration, water washing and drying of the filter cake, a yellow solid was obtained. GC analysis showed that the yield of 2-bromo-9-fluorenone was 174 g, and the yield was 75%.

[0059] Example 6

[0060] A method for preparing 2-bromo fluorenone by air oxidation bromination, comprising the steps of:

[0061] In a reaction vessel, 180 g (1 mol) of fluorenone, 444 g (1.5 mol) of iron bromide, 1000 mL of water were added respectively, and an air balloon was connected. The reaction was stirred at 100 °C for 5 h. After the reaction was completed, it was cooled to room temperature. After filtration, water washing and drying of the filter cake, a yellow solid was obtained. GC analysis showed that the yield of 2-bromo-9-fluorenone was 174 g, and the yield was 75%.

[0062] Example 7

[0063] A method for preparing 2-bromo fluorenone by air oxidation bromination, comprising the steps of:

[0064] In a reaction vessel, 180 g (1 mol) of fluorenone, 444 g (1.5 mol) of iron bromide, 1000 mL of water were added respectively, and an air balloon was connected. The reaction was stirred at 100 °C for 5 h. After the reaction was completed, it was cooled to room temperature. After filtration, water washing and drying of the filter cake, a yellow solid was obtained. GC analysis showed that the yield of 2-bromo-9-fluorenone was 174 g, and the yield was 75%.

[0065] Comparative Example 8 (catalyst was added in a different way, iron oxide and hydrobromic acid were added, which is equivalent to adding ferric bromide, and after the reaction, iron oxide was generated, and ferric bromide was regenerated by using hydrogen bromide)

[0066] A method for preparing 2-bromo fluorenone by air oxidation and bromination, comprising the following steps:

[0067] In a reaction vessel, 180 g (1 mol) of fluorenone, 240 g (1.5 mol) of iron sesquioxide, 760 g (4.5 mol) of 48% hydrobromic acid, 600 mL of water were added respectively, 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 lowered to room temperature. After filtration, water washing of the filter cake and drying, 150 g of yellow solid 2-bromo-9-fluorenone was obtained, with a yield of 72%.

[0068] Example 9

[0069] A method for preparing 2-bromo fluorenone by air oxidation and bromination, comprising the following steps:

[0070] In a reaction vessel, 180 g (1 mol) of fluorenone, 888 g (3 mol) of ferric bromide, 1000 mL of water were added respectively, 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 lowered to room temperature. After filtration, water washing of the filter cake and drying, 194 g of 2-bromo-9-fluorenone was obtained, with a yield of 85% by GC analysis.

[0071] Example 10

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

[0073] Table 1 shows the data of the number of times the catalyst was recycled and the yield of 2-bromo fluorenone during the preparation process. As can be seen from the table, the catalyst can be recycled and reused multiple times, and the activity of the catalyst does not decrease significantly.

[0074] Table 1 shows the data of the number of times the catalyst was recycled and the yield of 2-bromo fluorenone during the preparation process. As can be seen from the table, the catalyst can be recycled and reused multiple times, and the activity of the catalyst does not decrease significantly.

[0075]

[0076]

[0077] The application uses ferric bromide as bromine source and strong acid catalyst, and also as oxidation catalyst, avoiding using volatile bromine and hydrogen bromide.The specific steps are as follows: adding fluorenone, ferric bromide and water in a reaction container, reacting at a certain reaction temperature for a period of time, separating phases, distilling and purifying to obtain product 2-bromofluorenone.Ferric bromide can be oxidized into bromine and iron oxide by air for brominating fluorenone, and also can be used as strong Lewis acid catalyst for catalyzing bromination of fluorenone to obtain 2-bromofluorenone.Ferric bromide can be directly obtained from reaction system of iron oxide and hydrobromic acid;after reaction, the iron oxide and ferric bromide aqueous solution can be directly added into hydrogen bromide to regenerate ferric bromide solution for entering next reaction cycle; using ferric bromide as catalyst and bromine source, the volatility of hydrogen bromide is reduced, the utilization rate of hydrogen bromide is improved, and the safety of the process is ensured.The reaction process uses water as solvent and normal pressure air as oxidant, which is safe and efficient, and has good industrial application prospect.

[0078] The method uses air as an oxidizing agent, does not need to use strong oxidants such as hydrogen peroxide or chlorine, has lower environmental pollution and risk, and meets the requirements of green chemistry; the air oxidation reaction is generally more mild, avoiding the toxic or dangerous byproducts that may be produced in traditional oxidation processes, improving the safety and environmental protection of the reaction; iron bromide acts as a bromine source and a catalyst in the reaction, reducing the number of reaction steps and costs. Iron bromide is a common and relatively inexpensive chemical reagent that can provide good reaction results, while also facilitating control of reaction conditions and simplifying reaction operations; iron bromide as a catalyst helps to improve the selectivity and efficiency of the reaction, avoiding the use of excess bromine in traditional bromination methods, reducing unnecessary byproducts in the reaction; using iron bromide as a bromine source, a strong acid catalyst and an oxidation catalyst has significant advantages. First, iron bromide can play multiple roles in the reaction, both as an oxidizing agent to provide a bromine source and through catalytic action to accelerate the reaction. This multifunctional catalytic effect reduces the need for other chemical reagents, simplifies the process flow and reduces reaction costs. In addition, the iron bromide-catalyzed oxidation reaction is more mild than traditional methods, avoiding side reactions that may be triggered at high reaction temperatures, thereby improving the selectivity of the reaction and the purity of the product. Hydrogen bromide is a volatile and irritating chemical substance, and in traditional bromination processes, the volatility of hydrogen bromide is relatively high, which may cause environmental pollution and safety hazards. However, the use of iron bromide as a catalyst can effectively reduce the volatility of hydrogen bromide, promote the more efficient use of hydrogen bromide, and improve the safety of the reaction. After the reaction of hydrogen bromide with the aqueous iron bromide solution, the generated hydrogen bromide gas will be fixed in the reaction system, reducing the possibility of volatilization and reducing the risk of operators coming into contact with harmful gases. In addition, after the reaction is completed, the aqueous solution of iron oxide and iron bromide can be directly regenerated with hydrogen bromide to generate a new iron bromide solution. This recycling process not only saves raw material costs but also greatly reduces waste generation, improving resource utilization efficiency and making 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 meets the principles of green chemistry.

[0079] At the same time, the reaction temperature is controlled at 50-110℃, and the time is between 1-10 hours, which means that the reaction is carried out at moderate temperature, which can effectively control the reaction rate and reduce the occurrence of side reactions; mild reaction conditions reduce energy consumption and can reduce the generation or decomposition of harmful substances caused by high temperature, thereby improving the quality and yield of the product; 2-bromofluorenone is an important intermediate of electroluminescent materials, which is widely used in OLED, LED and other electronic and optoelectronic devices, 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, which has significant economic benefits.

[0080] The above merely illustrates the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application, on the basis of the technical scheme, falls within the protection scope of the present application.

Claims

1. A process for the production of 2-bromofluorenones by air oxidation bromination, characterized in that, The method comprises the following steps: 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; The bromine source is iron bromide; The catalyst is iron bromide.

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

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

4. The method for preparing 2-bromofluorenone by air oxidation bromination according to claim 1, characterized in that, The post-treatment comprises phase separation, distillation and purification treatment in sequence.

5. The method of claim 1, wherein the air oxidation bromination of fluorenone to produce 2-bromofluorenone is carried out in the presence of a base. The reaction is stirred, and the stirring speed is 300-1000 rpm.

6. The method of claim 1, wherein the method is characterized by, After the reaction, the yield of 2-bromofluorenone is 70%~85%.

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