Preparation method of 4, 4 '-dinitrodiphenyl ether

Abstract

A preparation method of 4, 4 '-dinitrodiphenyl ether belongs to the field of organic synthesis, and comprises the following steps: step 1, weighing p-nitrochlorobenzene, sodium carbonate, a phase transfer catalyst and DMF according to a ratio; 2, mixing p-nitrochlorobenzene, sodium carbonate, a phase transfer catalyst and DMF, and carrying out a reaction; 3, filtering after the reaction is completed, and cooling filtrate to crystallize; 4, after cooling crystallization of the filtrate is completed, filtering and washing; and 5, drying to obtain the product 4, 4 '-dinitrodiphenyl ether. The synthesis method is simple to operate, p-nitrochlorobenzene is converted into 4, 4 '-dinitrodiphenyl ether by adding a proper phase transfer catalyst, sodium p-nitrophenolate is not used any more, the reaction risk is reduced, the reaction steps are shortened, impurities are few, the conversion rate is high, the purity is high, the production efficiency is improved, and the solvent DMF can be recycled and reused.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis, specifically a method for preparing 4,4'-dinitrodiphenyl ether. Background Technology

[0002] 4,4'-Dinitrodiphenyl ether, also known as p-nitrobenzene ether, is a yellow crystal with a melting point of 140-145℃, a boiling point of 386.2±17.0℃ (760mmHg), a molecular weight of 260, and a density of 1.40 g / cm³. 3 Flash point: 174±22.9℃, CAS number: 101-63-3, molecular formula: C 12 H8N2O5 is soluble in DMF and DMAC. 4,4'-Dinitrodiphenyl ether is an important organic synthesis intermediate used to synthesize polyimides, polyether ether ketones, and sand red dyes. One of the raw materials used in the synthesis of 4,4'-dinitrodiphenyl ether is sodium p-nitrophenolate, also known as 4-nitrophenol sodium, with the molecular formula C6H4NNaO3 and a molecular weight of 161. Its physicochemical properties are: pale yellow crystals, melting point >300℃, miscible with water. Sodium p-nitrophenolate, as one of the main raw materials for the synthesis of 4,4'-dinitrodiphenyl ether, has the following disadvantages: 1. Sodium p-nitrophenolate is highly hazardous; it is flammable when exposed to open flames or high heat, and its powder can form an explosive mixture with air; 2. The synthesis route is long and energy-intensive.

[0003] 4,4'-Dinitrodiphenyl ether can be synthesized from p-nitrochlorobenzene and sodium p-nitrophenolate, but the synthesis route is long, energy-intensive, requires large investment, and is highly dangerous.

[0004] 4,4'-dinitrodiphenyl ether can also be synthesized using p-nitrochlorobenzene and sodium hydroxide as raw materials, with isopropanol (IPA) as the solvent.

[0005] The technical solution disclosed in the literature "Synthesis of 4,4'-dinitrodiphenyl ether" (Zheng Zhengqi [J] Environment and Development, 2001, 16, (3): 18-19) is as follows: A certain amount of p-nitrochlorobenzene, NaOH and isopropanol are added to a three-necked flask equipped with a reflux condenser, stirrer and thermometer. Stirring is started, and the temperature is raised to 80℃~100℃ in about 0.5h and kept at 6.5h. Heating and stirring are stopped and the temperature is allowed to cool naturally to room temperature before filtration. The filtrate is recycled. The filter cake is washed with 95℃ dilute NaOH solution and filtered while hot. It is then dried at 105℃ to obtain the crude yellow solid product 4,4'-dinitrodiphenyl ether.

[0006] The crude product was placed in a 50 mL flask equipped with a reflux condenser and a stirrer. Approximately 20 mL of ethyl acetate and a suitable amount of activated carbon were added. The mixture was heated and stirred, with additional ethyl acetate added until the solid was completely dissolved at boiling temperature. Then, 3-4 mL of ethyl acetate was added and the mixture was boiled for approximately 3 minutes. The mixture was immediately filtered through a Buchner funnel preheated to approximately 70°C, and the filter residue was discarded. The filtrate was cooled to 5°C, and the solid was allowed to precipitate and filtered. Finally, the crystals were transferred to a watch glass and dried in a vacuum oven at 80°C. This method yields a high purity (99%) but a low yield, less than 80%.

[0007] The technical solution disclosed in the literature "Study on the Synthesis Process of 4,4'-Dinitrodiphenyl Ether" (Bai Min, Chen Tianyun [J]. Anhui Chemical Industry, 2011, (4): 36-38) is as follows: A certain amount of water is added to a three-necked flask equipped with a reflux condenser, a stirrer and a thermometer, and then p-nitrochlorobenzene, p-nitrophenol and dimethyl sulfoxide are added respectively. The mixture is stirred and the temperature is raised to 100-120℃. Sodium hydroxide is slowly added and the temperature is raised to 130-160℃ to continue the reaction. After the reaction is completed, the mixture is allowed to cool naturally to room temperature, and then water is added. A yellow substance is precipitated. After standing for a period of time, the mixture is filtered, the filter cake is washed with hot sodium hydroxide solution and filtered while hot, and then dried to obtain a yellow solid 4,4'-dinitrodiphenyl ether with a yield of 85.3%. The product yield obtained by this method is low.

[0008] The technical solution disclosed in the literature "Research Progress on the Preparation of 4,4'-Dinitrodiphenyl Ether and its Reduction Product 4,4'-Diaminodiphenyl Ether" (Ding Jianfei, Wu Yibiao et al. [J]. New Chemical Materials, 2012, (8): 14-16) is as follows: using water as a solvent, p-nitrochlorobenzene, tetrabutylphosphorus chloride, sodium nitrite and sodium carbonate are added to a high-pressure reactor, heated to 140℃ and reacted for 5 hours. The product is washed with water and methanol respectively. Studies have shown that adding quaternary compounds to water not only reduces by-products but also lowers the risk of explosion. In addition, adding alkali metal or alkaline earth metal carbonates to the reactants is beneficial for absorbing nitrogen oxides. The product yield is 90%.

[0009] The technical solution disclosed in the literature "4,4'-dinitrodiphenyl ether and its reduction products" (Pan Weichun, Wu Yibiao et al. [J]. New Chemical Materials, 2013, (5): 133-135) is to add a certain amount of p-nitrochlorobenzene, sodium carbonate, sodium nitrite and DMF to a three-necked flask equipped with a reflux condenser, an electric stirrer and a thermometer, and heat and stir. After the reaction is completed, the DMF solvent is distilled off under reduced pressure, the residue is washed with a large amount of hot water above 90°C and filtered while hot, and the obtained yellow crystals are dried. The content and yield of the obtained product are both low. Summary of the Invention

[0010] This invention provides a method for preparing 4,4'-dinitrodiphenyl ether to overcome the deficiencies in the prior art.

[0011] This invention is achieved through the following technical solution: A method for preparing 4,4'-dinitrodiphenyl ether includes the following steps: Step 1: Weigh out p-nitrochlorobenzene, sodium carbonate, phase transfer catalyst, and DMF according to the specified ratio; Step 2: Mix p-nitrochlorobenzene, sodium carbonate, phase transfer catalyst, and DMF and then react them; Step 3: After the reaction is complete, filter the solution and cool the filtrate to allow crystals to precipitate. Step 4: After the filtrate has cooled and crystallized, filter and wash it. Step 5: After drying, the product 4,4'-dinitrodiphenyl ether is obtained.

[0012] In the preparation method of 4,4'-dinitrodiphenyl ether described above, the molar ratio of p-nitrochlorobenzene, sodium carbonate, phase transfer catalyst and DMF in step one is: 1:0.3-0.5:0.002-0.005:0.8-1.5.

[0013] In the preparation method of 4,4'-dinitrodiphenyl ether as described above, the phase transfer catalyst is any one or a mixture of two of tetrabutylammonium bromide and tetrabutylammonium chloride in any proportion.

[0014] The method for preparing 4,4'-dinitrodiphenyl ether as described above, wherein the DMF content is greater than 99.5%.

[0015] In the preparation method of 4,4'-dinitrodiphenyl ether described above, the reaction temperature in step two is 150-160℃ and the reaction time is 20-24h.

[0016] In the preparation method of 4,4'-dinitrodiphenyl ether described above, step three involves hot filtration, with the temperature controlled at 100-110℃ after filtration, followed by a cooling rate of 0.5-1℃ / min to 30-35℃ and holding at that temperature for 1 hour.

[0017] In the preparation method of 4,4'-dinitrodiphenyl ether described above, after filtration in step four, the crystals are washed with deionized water, and the mass ratio of deionized water to precipitated crystals is 1:1.

[0018] In the preparation method of 4,4'-dinitrodiphenyl ether described above, the drying temperature in step five is 80°C, the vacuum degree is 25 mmHg, and the drying time is 5-6 h.

[0019] The advantages of this invention are: the synthesis method of this invention is simple to operate, and by adding a suitable phase transfer catalyst, p-nitrochlorobenzene is converted into 4,4'-dinitrodiphenyl ether, eliminating the need for sodium p-nitrophenolate, reducing reaction risk, shortening reaction steps, reducing impurities, increasing conversion rate, and increasing purity; improving production efficiency; and the solvent DMF can be recycled. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is the purity detection spectrum of Example 1 of the present invention; Figure 2 This is the purity detection spectrum of Example 2 of the present invention; Figure 3 This is the purity detection spectrum of Embodiment 3 of the present invention. Detailed Implementation

[0022] 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. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1: 355g of p-nitrochlorobenzene (2.26mol), 131g of sodium carbonate (1.23mol), 300g of DMF (4.11mol), and 3.64g of tetrabutylammonium bromide (0.011mol) were mixed and heated to 165℃ and held for 24h. The mixture was then cooled to 110℃, and the salt was filtered to obtain a 4,4'-dinitrodiphenyl ether solution. The solution was further cooled at a rate of 0.5-1℃ / min until it reached 30℃ and was held for 1h. The solution was then filtered, washed with pure water, and the filter cake was dried in a vacuum drying oven at 25mmHg and 80℃ for 5h to obtain a purity of 99.6% (e.g., ...). Figure 1 The product yielded 274g of 4,4'-dinitrodiphenyl ether (as shown), with a molar yield of 92.4%.

[0024] Example 2: 355g of p-nitrochlorobenzene (2.26mol), 131g of sodium carbonate (1.23mol), 300g of DMF (4.11mol), and 3.64g of tetrabutylammonium chloride (0.011mol) were mixed and heated to 155℃ and held for 24h. The mixture was then cooled to 110℃, and the salt was filtered to obtain a 4,4'-dinitrodiphenyl ether solution. The solution was further cooled at a rate of 0.5-1℃ / min until it reached 35℃ and was held for 1h. The solution was then filtered, washed with pure water, and the filter cake was dried in a vacuum drying oven at 25mmHg and 80℃ for 5h to obtain a purity of 99.7% (e.g., ...). Figure 2 The molar yield of 277g of 4,4'-dinitrodiphenyl ether product (as shown) was 93.4%.

[0025] Example 3: 355g of p-nitrochlorobenzene (2.26mol), 131g of sodium carbonate (1.23mol), 300g of DMF (4.11mol), 1.82g of tetrabutylammonium bromide (0.006mol), and 1.82g of tetrabutylammonium chloride (0.007mol) were mixed and heated to 150℃ and held for 24h. The mixture was then cooled to 110℃, and the salt was filtered to obtain a 4,4'-dinitrodiphenyl ether solution. The solution was further cooled at a rate of 0.5-1℃ / min until it reached 33℃ and held for 1h. The solution was then filtered, washed with pure water, and the filter cake was dried in a vacuum drying oven at 25mmHg and 80℃ for 5h to obtain a purity of 99.5% (e.g., ...). Figure 3 The molar yield of 275g of 4,4'-dinitrodiphenyl ether product (as shown) was 92.7%.

[0026] 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 preparing 4,4'-dinitrodiphenyl ether, characterized in that: Includes the following steps: Step 1: Weigh p-nitrochlorobenzene, sodium carbonate, phase transfer catalyst, and DMF according to the specified ratio; Step 2: Mix p-nitrochlorobenzene, sodium carbonate, phase transfer catalyst, and DMF and then react them; Step 3: After the reaction is complete, filter the solution and cool the filtrate to allow crystals to precipitate. Step 4: After the filtrate has cooled and crystallized, filter and wash it. Step 5: After drying, the product 4,4'-dinitrodiphenyl ether is obtained.

2. The method for preparing 4,4'-dinitrodiphenyl ether according to claim 1, characterized in that: The molar ratio of p-nitrochlorobenzene, sodium carbonate, phase transfer catalyst, and DMF in step one is 1:0.3-0.5:0.002-0.005:0.8-1.

5.

3. The method for preparing 4,4'-dinitrodiphenyl ether according to claim 1, characterized in that: The phase transfer catalyst is any one or a mixture of two of tetrabutylammonium bromide and tetrabutylammonium chloride in any proportion.

4. The method for preparing 4,4'-dinitrodiphenyl ether according to claim 1, characterized in that: The DMF content is greater than 99.5%.

5. The method for preparing 4,4'-dinitrodiphenyl ether according to claim 1, characterized in that: The reaction temperature in step two is 150-160℃, and the reaction time is 20-24h.

6. The method for preparing 4,4'-dinitrodiphenyl ether according to claim 1, characterized in that: In step three, hot filtration is used, and the temperature after filtration is controlled at 100-110℃. Then, the temperature is reduced to 30-35℃ at a cooling rate of 0.5-1℃ / min and kept at that temperature for 1 hour.

7. The method for preparing 4,4'-dinitrodiphenyl ether according to claim 1, characterized in that: In step four, after filtration, the crystals are washed with deionized water at a mass ratio of 1:

1.

8. The method for preparing 4,4'-dinitrodiphenyl ether according to claim 1, characterized in that: In step five, the drying temperature is 80℃, the vacuum degree is 25mmHg, and the drying time is 5-6 hours.

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