Preparation method of 2-alkylanthraquinone

Abstract

The invention discloses a preparation method of 2-alkyl anthraquinone, which comprises the following steps: dissolving a raw material 2-alkyl anthracene or 2-alkyl anthrone in a solvent, and carrying out catalytic oxidation in an oxygen-containing atmosphere to obtain 2-alkyl anthraquinone; the method disclosed by the invention has the advantages of being green and efficient.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic synthesis, and particularly relates to a method for preparing 2-alkylanthraquinone by green catalytic oxidation of 2-alkylanthrone or 2-alkylanthracene. Background Art

[0002] 2-alkylanthraquinone is a multifunctional organic compound with high added value and plays a core role in the fields of chemical engineering, materials and energy. It is an irreplaceable catalyst carrier in the industrial production of hydrogen peroxide (H2O2). By optimizing the hydrogen-oxygen combination efficiency, it directly improves the synthesis performance of H2O2. At present, more than 95% of the global H2O2 production capacity depends on its catalytic system, becoming an important support for green chemical engineering. In addition to the hydrogen peroxide field, 2-alkylanthraquinone shows unique value in many high-tech fields: in the dye industry, it can be used as the parent structure of anthraquinone dyes, and the dyeing performance and light fastness can be adjusted by introducing functional alkyl side chains; in the field of electronic materials, its derivatives are used to manufacture highly conductive polymers and luminescent materials in OLED display devices; in polymerization reactions, it can be used as a radical inhibitor or crosslinking agent to improve the mechanical strength and thermal stability of polymer materials. In addition, its excellent redox properties are also applied in the environmental protection field, such as catalytic degradation of pollutants in wastewater treatment and functional modification of the separator of lithium-sulfur batteries in new energy batteries. Research shows that through molecular structure design, 2-alkylanthraquinone can be further extended to frontier fields such as drug synthesis and photocatalytic hydrogen production. Its multifunctionality stems from the precise regulation of the steric effect and electronic properties of alkyl substituents.

[0003] The current synthesis of 2-alkylanthraquinone still faces multiple challenges: The traditional phthalic anhydride method relies on strongly corrosive reagents such as aluminum trichloride and fuming sulfuric acid, generating several tons of highly polluting waste liquid for every 1 ton of product produced, imposing a heavy environmental burden; in the alkylanthraquinone oxidation method, problems such as incomplete oxidation of alkylanthraquinone still exist. In terms of the catalyst system, ionic liquids (such as [Bmim]Cl-AlCl3) are environmentally friendly but have high costs, high viscosities, and a significant decrease in activity after loading (the selectivity drops to 88% after recycling); while metal complexes (such as rhodium and copper complexes) have high catalytic efficiency (yield > 90%), but the ligand synthesis is complex and difficult to recycle, limiting industrialization. There are also contradictions in the selection of oxidants: tert-butyl hydroperoxide and hypervalent iodine are costly and have poor safety, and although oxygen oxidation is green, it requires high temperature and high pressure (120°C, 150 bar, 24 hours), with a conversion rate of only 62%-76% and prominent energy consumption; the naphthoquinone method involves multiple steps to synthesize intermediates (such as 2-tert-amyl-1,3-butadiene) and involves acetylene gas, with a long process and low yield. In addition, existing improvement technologies such as zeolite molecular sieve modification and one-pot methods mostly remain at the laboratory stage, with problems such as insufficient catalyst stability (such as activity decay after recycling) and the lack of continuous production equipment, making it difficult to meet the large-scale industrialization demand. In summary, developing highly selective catalysts, optimizing the green oxidation system, simplifying the process route, and promoting technology transformation are the key directions to break through the existing bottlenecks.

[0004] Therefore, the present invention is proposed. Summary of the Invention

[0005] The present invention provides a green catalytic system and process method for catalytic oxidation of 2-alkylanthraquinone using 2-alkylanthrone or 2-alkylanthracene as raw materials.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing 2-alkylanthraquinone, wherein a solution of 2-alkylanthracene or 2-alkylanthrone as a raw material is dissolved in a solvent and catalytically oxidized to 2-alkylanthraquinone in an oxygen-containing atmosphere; as shown in the following formula:

[0008]

[0009] Preferably, the oxygen-containing atmosphere is one of air, oxygen-enriched air, oxygen, or hydrogen peroxide.

[0010] Preferably, the solvent is one or more of toluene, C 8-10 heavy aromatic hydrocarbons, trioctyl phosphate, or diisobutyl carbinol.

[0011] Preferably, the catalyst is a CeO2 and Al2O3 composite, and the atomic ratio of Ce to Al in the composite is (1 / 199)-(30 / 70).

[0012] Further preferably, the atomic ratio of Ce to Al is 3 / 97.

[0013] Preferably, when the raw material is 2-alkylanthracene, the reaction temperature is from 100 °C to the reflux temperature of the solution, and the reaction time is 10 - 20 h; when the raw material is 2-alkylanthrone, the reaction temperature is from 20 °C to the reflux temperature of the solution, and the reaction time is 2 - 10 h.

[0014] Preferably, the preparation method of the catalyst comprises the following steps:

[0015] (1) Dissolve the aluminum source in absolute ethanol, add the cerium nitrate solution, and heat under reflux for a period of time;

[0016] (2) Add the nitric acid solution and reflux for another period of time to obtain a gel solution;

[0017] (3) Dry the gel solution in air for a period of time, and then dry it under vacuum for a period of time;

[0018] (4) After calcining at a high temperature for a period of time, the catalyst is obtained.

[0019] Preferably, in step (1), the aluminum source is an organoaluminum or an inorganic aluminum salt, and the cerium nitrate solution is a cerium nitrate solution or a cerous nitrate solution; in step (2), the heating reflux temperature after adding the nitric acid solution is 80 °C - 100 °C, and the time is 10 - 20 h; in step (3), the temperature of vacuum drying is 50 - 100 °C, and the time is not less than 12 h; in step (4), the calcination temperature is 500 - 700 °C.

[0020] Preferably, the organoaluminum is aluminum tri-sec-butoxide or aluminum isopropoxide; the inorganic aluminum salt is one or more of aluminum nitrate, aluminum sulfate or aluminum chloride.

[0021] Preferably, the addition amount of the cerium nitrate solution is such that the atomic ratio of cerium atoms in the cerium nitrate solution to aluminum atoms in the aluminum source is (1 / 199) - (30 / 70); the heating reflux temperature for adding the cerium nitrate solution is 80 °C - 100 °C, and the time is 1 - 10 h.

[0022] Advantages of the present invention:

[0023] The present invention for the first time uses 2-alkylanthrone or 2-alkylanthracene as a raw material, dissolves it in a preferred solvent, and under an oxygen-containing atmosphere, uses a self-made CeO₂ and Al₂O₃ composite (containing CeAlO₃) as a catalyst to catalytically oxidize to prepare 2-alkylanthraquinone, realizing the directional oxidation of anthrone. Compared with the traditional process, the method of the present invention has the advantages of mild reaction conditions, recyclable catalyst, high yield, high product purity (≥99%), and no harmful by-products, and is suitable for industrial production. The method of the present invention has the advantages of being green and efficient. Description of the Drawings

[0024] Figure 1 XRD pattern of the catalyst prepared in the present invention when the atomic ratio of Ce to Al is 3 / 97.

[0025] Figure 2 TEM pattern of the catalyst prepared in the present invention when the atomic ratio of Ce to Al is 3 / 97.

[0026] Figure 3 Conversion rate of 2-ethylanthraquinone over time in the present invention.

[0027] Figure 4 Conversion rate of 2-pentylanthraquinone over time in the present invention.

[0028] Figure 5 1H NMR spectrum of 2-ethylanthraquinone in the present invention.

[0029] Figure 6 1H NMR spectrum of 2-pentylanthraquinone in the present invention. Detailed Description of the Invention

[0030] The technical solution of the present invention will be further described below in conjunction with the specific embodiments. It should be noted that the following examples are only for detailed description and explanation of the present invention, and the application scope of the present invention is not limited by the conditions in the examples.

[0031] Example 1: Preparation of the catalyst CeO2 and Al2O3 composite, the steps are as follows:

[0032] (1) Dissolve 12.75 g of tri-sec-butoxyaluminum in 75.09 g of absolute ethanol and stir for 5 minutes to obtain solution A;

[0033] (2) Dissolve the required amount of cerium nitrate hexahydrate in 13.05 g of distilled water, and then add it to solution A; heat the mixture to 80 °C and reflux for 1 h, then add 12.5 mL of nitric acid solution with a concentration of 0.1 mol / L, and continue to reflux for 14 h to obtain a gel solution;

[0034] (3) After the gel solution is naturally cooled to room temperature, first dry it in air at 70 °C for 24 h, and then dry it under vacuum at 80 °C overnight;

[0035] (4) In air, heat it to 600 °C at a heating rate of 3 °C / min and keep calcining for 5 hours; three CeO2 and Al2O3 composite catalysts with the atomic ratio of Ce to Al of x = 3 / 197, 3 / 97 and 7 / 93 are obtained.

[0036] The steps and conditions for the preparation method of γ-Al2O3 are the same as above, but cerium nitrate hexahydrate is not added.

[0037] Figure 1To obtain the XRD pattern of the catalyst with an atomic ratio x of Ce to Al of 3 / 97. From Figure 1 It can be seen that weak characteristic diffraction peaks at 2θ° = 28.6 and 33.0° are respectively attributed to the (111) and (200) crystal planes of cubic fluorite phase CeO2 (JCPDS 34 - 0394, space group Fm3m); two relatively broad characteristic diffraction peaks appear at 2θ° = 45.8 and 67.0°, corresponding to the (400) and (440) crystal planes of γ - Al2O3 (JCPDS Card No.10 - 0425) respectively; indicating the presence of CeO2 and γ - Al2O3 structures in the catalyst.

[0038] Figure 2 To obtain the TEM pattern of the catalyst with an atomic ratio x of Ce to Al of 3 / 97. From Figure 2 A lattice spacing of 0.27 nm corresponding to the (110) plane of CeAlO3 can be observed, which indicates the presence of the CeAlO3 phase in the catalyst; in addition, the (111) crystal plane of cubic fluorite CeO2 with a plane spacing of 0.31 nm is shown for the catalyst with x = 3 / 97; indicating the presence of CeO2 and CeAlO3 structures in the catalyst with x = 3 / 97.

[0039] Example 2: Preparation of 2 - ethylanthraquinone; raw material: 2 - ethyl - 9 - anthrone; oxygen - containing atmosphere is air.

[0040] Into a 50 - ml reaction flask, 0.1000 g of 2 - ethyl - 9 - anthrone, 10 g of mesitylene and 0.2500 g of the catalyst obtained in Example 1 with an atomic ratio of Ce to Al of x = 3 / 97 were added in sequence; the temperature was raised to 40 °C and stirred for reaction. The reaction solution was centrifuged to recover the catalyst, and the organic phase was rotary - evaporated to remove the solvent to obtain 2 - ethylanthraquinone; the conversion rate of 2 - ethyl - 9 - anthrone at 1 h - 7 h of reaction was recorded respectively, as Figure 3 shown; after 7 h of reaction, 0.0998 g of 2 - alkylanthraquinone was obtained, and the yield was 99%. Figure 5 The following is the 1H NMR spectrum of the obtained product, proving that the product is 2 - ethylanthraquinone. The reaction is shown as follows:

[0041]

[0042] Example 3: Preparation of 2 - ethylanthraquinone. Raw material: 2 - ethyl - 10 - anthrone; oxygen - containing atmosphere is air.

[0043] Into a 50 ml reaction flask, 0.1000 g of 2-ethylanthrone, 10 g of mesitylene and 0.2500 g of the catalyst obtained in Example 1 with an atomic ratio of Ce and Al of x = 3 / 97 were added in sequence. The temperature was raised to 40 °C and the reaction was stirred. The catalyst was recovered by centrifugation of the reaction solution, and the organic phase was evaporated to remove the solvent to obtain 2-ethylanthraquinone. The conversion rate of 2-ethylanthrone at 1 h - 7 h of the reaction was recorded respectively, as Figure 3 shown; after 7 h of the reaction, 0.0997 g of 2-alkylanthraquinone was obtained, and the yield was 99%. Figure 5 The following is the 1H NMR spectrum of the obtained product, which proves that the product is 2-ethylanthraquinone. The reaction is shown by the following formula:

[0044]

[0045] Example 4: Preparation of 2-ethylanthraquinone. Raw materials: 2-ethylanthrone mixture (a mixture of 2-ethyl-9-anthrone:2-ethyl-10-anthrone = 3:2); the oxygen-containing atmosphere is air.

[0046] Into a 50 ml reaction flask, 0.1000 g of the 2-ethylanthrone mixture, 10 g of mesitylene and 0.2500 g of the catalyst obtained in Example 1 with an atomic ratio of Ce and Al of x = 3 / 97 were added in sequence. The temperature was raised to 40 °C and the reaction was stirred. The catalyst was recovered by centrifugation of the reaction solution, and the organic phase was evaporated to remove the solvent to obtain 2-ethylanthraquinone. The conversion rate of 2-ethylanthrone at 1 h - 7 h of the reaction was recorded respectively, as Figure 3 shown; after 7 h of the reaction, 0.0996 g of 2-alkylanthraquinone was obtained, and the yield was 99%. Figure 5 The following is the 1H NMR spectrum of the obtained product, which proves that the product is 2-ethylanthraquinone.

[0047] The reaction was carried out for 3 hours using catalysts with atomic ratios of Ce and Al of x = 3 / 197 and 7 / 93, and the conversion rate of 2-ethylanthrone was recorded. γ-Al2O3 prepared in Example 1 and commercially available CeO2 were used as catalysts for comparison. As shown in Table 1 below:

[0048] Table 1: 3 h conversion rate of 2-ethylanthrone

[0049]

[0050] The reaction schematic diagram of this example is shown by the following formula, and the reaction atmosphere is air:

[0051]

[0052] Example 5: Preparation of 2-amylanthraquinone. Raw materials: 2-amyl-9-anthrone; the oxygen-containing atmosphere is air.

[0053] Into a 50 ml reaction flask, 0.1000 g of 2-pentylanthrone, 10 g of mesitylene, and 0.2500 g of the catalyst obtained in Example 1 with an atomic ratio of x = 3 / 97 were added in sequence. The temperature was raised to 40 °C and the reaction was stirred. The catalyst was recovered by centrifugation of the reaction solution, and the organic phase was evaporated to remove the solvent to obtain 2-pentylanthraquinone. The conversion rates of 2-pentylanthrone at 1 h - 7 h of reaction were recorded respectively, as Figure 4 shown; after 7 h of reaction, 0.0995 g of 2-pentylanthraquinone was obtained, and the yield was 99%. Figure 6 The following is the 1H NMR spectrum of the obtained product, which proves that the product is 2-pentylanthraquinone. The reaction is shown as follows:

[0054] Example 6: Preparation of 2-pentylanthraquinone. Raw materials: 2-pentyl-10-anthrone; the oxygen-containing atmosphere is air.

[0055] Into a 50 ml reaction flask, 0.1000 g of 2-pentylanthrone, 10 g of mesitylene, and 0.2500 g of the catalyst obtained in Example 1 with an atomic ratio of x = 3 / 97 were added in sequence. The temperature was raised to 40 °C and the reaction was stirred. The catalyst was recovered by centrifugation of the reaction solution, and the organic phase was evaporated to remove the solvent to obtain 2-pentylanthraquinone. The conversion rates of 2-pentylanthrone at 1 h - 7 h of reaction were recorded respectively, as Figure 4 shown; after 7 h of reaction, 0.0992 g of 2-pentylanthraquinone was obtained, and the yield was 99%. Figure 6 The following is the 1H NMR spectrum of the obtained product, which proves that the product is 2-pentylanthraquinone. The reaction is shown as follows:

[0056] Example 7: Preparation of 2-pentylanthraquinone. Raw materials: 2-pentylanthrone mixture (a mixture of 2-pentyl-9-anthrone:2-pentyl-10-anthrone = 2:1); the oxygen-containing atmosphere is air.

[0057] Into a 50 ml reaction flask, 0.1000 g of 2-pentylanthrone, 10 g of mesitylene, and 0.2500 g of the Ce x Al catalyst obtained in Example 1 with an atomic ratio of x = 3 / 197 were added in sequence. The temperature was raised to 40 °C and the reaction was stirred. The catalyst was recovered by centrifugation of the reaction solution, and the organic phase was evaporated to remove the solvent to obtain 2-pentylanthraquinone. The conversion rates of 2-pentylanthrone at 1 h - 7 h of reaction were recorded respectively, as Figure 4 shown; after 7 h of reaction, 0.0994 g of 2-pentylanthraquinone was obtained, and the yield was 99%. Figure 6 The following is the 1H NMR spectrum of the obtained product, which proves that the product is 2-pentylanthraquinone.

[0058] React for 3 hours using catalysts with the atomic ratio of Ce to Al being x = 3 / 197 and 7 / 93, record the conversion rate of 2-pentylanthraquinone, and use γ-Al2O3 prepared in Example 1 and commercially available CeO2 as catalysts for comparison. As shown in Table 2 below:

[0059] Table 2: 3h Conversion Rate of 2-Pentylanthraquinone

[0060]

[0061] The reaction schematic diagram of this example is shown in the following formula, and the reaction atmosphere is air.

[0062]

[0063] It can be seen from Example 4 and Example 7 that under the same conditions, the composite catalyst with the atomic ratio of Ce to Al being x = 3 / 97 has the best effect. On the basis of Example 7, change the reaction atmosphere to pure oxygen, use the catalyst with x = 3 / 97; and use γ-Al2O3 prepared in Example 1 and commercially available CeO2 as catalysts for comparison. The results are shown in Table 3 below:

[0064] Table 3: 3h Conversion Rate of 2-Pentylanthraquinone (Oxygen Atmosphere)

[0065]

[0066] It can be seen from Table 3 that when the reaction atmosphere is pure oxygen, under the same conditions, the conversion rate can increase faster.

[0067] Example 8: Preparation of 2-Pentylanthraquinone. Raw materials: 2-Pentylanthracene; The oxygen-containing atmosphere is air.

[0068] Into a 50 ml reaction flask, sequentially add 0.1000 g of 2-pentylanthracene, 10 g of mesitylene, and 0.2500 g of the catalyst with the atomic ratio of Ce to Al being x = 3 / 97 obtained in Example 1. Heat up to 140 °C and stir to react. Centrifuge the reaction solution to recover the catalyst, and rotary evaporate the organic phase to remove the solvent to obtain 2-pentylanthraquinone. Record the conversion rate of 2-pentylanthraquinone at 1 h - 15 h of reaction respectively; after 15 h of reaction, 0.0989 g of 2-pentylanthraquinone is obtained, and the yield is 99%.

[0069] Change the above reaction catalyst to γ-Al2O3 prepared in Example 1 for comparison, and the result is: 0.0051 g of 2-pentylanthraquinone is obtained after 15 h of reaction, and the yield is 5%.

[0070] The reaction schematic diagram of this example is shown in the following formula, and the reaction atmosphere is air.

[0071]

[0072] Example 9: Catalyst recycling effect.

[0073] Based on Example 7; using 2-pentylanthrone as the reaction raw material, a catalyst with an atomic ratio of Ce to Al of x = 3 / 97 was used for the regeneration experiment, and the conditions for each reaction were exactly the same; after each reaction, the catalyst was washed 3 times with ethanol, dried at 100 °C for 12 h, and then used for subsequent catalytic experiments. The results are shown in Table 4 below:

[0074] Table 4: Catalyst recycling experiment results

[0075]

[0076] As can be seen from Table 4, the catalyst with an atomic ratio of Ce to Al of x = 3 / 97 was recycled five times, and the catalytic efficiency hardly changed. This shows that the catalyst can be recycled.

[0077] The above is only used to introduce the specific implementation manners of the present invention in detail, but the technical solutions proposed by the present invention are not limited to the above methods. Without departing from the basic principles of the present technology, equivalent modifications and changes made by those skilled in the art to the technology proposed by the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing 2-alkylanthraquinone, characterized in that: The raw material 2-alkylanthracene or 2-alkylanthrone is dissolved in a solvent and catalytically oxidized to 2-alkylanthraquinone in an oxygen-containing atmosphere; as shown in the following formula:

2. The preparation method according to claim 1, characterized in that: The oxygen-containing atmosphere is one of air, oxygen-enriched air, or pure oxygen.

3. The preparation method according to claim 1, characterized in that: The solvents are toluene, C 8-10 One or more of heavy aromatics, trioctyl phosphate or diisobutyl carbinol.

4. The preparation method according to claim 1, characterized in that: The catalyst is a composite of CeO2 and Al2O3, and the ratio of Ce and Al atoms in the composite is (1 / 199)-(30 / 70).

5. The preparation method according to claim 4, characterized in that: The atomic ratio of Ce to Al is 3 / 97.

6. The preparation method according to claim 1, characterized in that: When the raw material is 2-alkylanthracene, the reaction temperature is 100°C to the solution reflux temperature, and the reaction time is 10-20 hours; when the raw material is 2-alkylanthrone, the reaction temperature is 20°C to the solution reflux temperature, and the reaction time is 2-10 hours.

7. The preparation method according to claim 4, characterized in that: The preparation method of the catalyst comprises the following steps: (1) dissolving an aluminum source in anhydrous ethanol, adding a cerium nitrate solution and heating under reflux for a period of time; (2) adding nitric acid solution and refluxing for a period of time to obtain a gel solution; (3) drying the gel solution in air for a period of time, and then vacuum drying it for a period of time; (4) After high-temperature calcination for a period of time, the catalyst is obtained.

8. The preparation method according to claim 7, characterized in that: In step (1), the aluminum source is organic aluminum or inorganic aluminum salt, and the cerium nitrate solution is cerium nitrate solution or cerous nitrate solution; in step (2), the heating reflux temperature after adding the nitric acid solution is 80°C-100°C, and the time is 10-20h; in step (3), the vacuum drying temperature is 50-100°C, and the time is not less than 12h; in step (4), the calcination temperature is 500-700°C.

9. The preparation method according to claim 8, characterized in that: The organic aluminum is tri-sec-butoxy aluminum or aluminum isopropoxide; the inorganic aluminum salt is one or more of aluminum nitrate, aluminum sulfate or aluminum chloride.

10. The preparation method according to claim 7, characterized in that: The amount of the cerium nitrate solution added is such that the ratio of the number of cerium atoms in the cerium nitrate solution to the number of aluminum atoms in the aluminum source is (1 / 199)-(30 / 70); The cerium nitrate solution is heated to reflux at a temperature of 80° C.-100° C. for a time of 1-10 hours.

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