A method for catalytic selective oxidation of naphthylarene by molecular oxygen to prepare naphthoquinone compounds
The preparation of naphthoquinone compounds by oxidizing naphthyl aromatics with molecular oxygen under mild liquid-phase conditions using Co-based catalysts solves the environmental pollution and high cost problems of existing naphthoquinone compound synthesis technologies, and realizes efficient and safe production of naphthoquinone compounds.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2024-11-29
- Publication Date
- 2026-05-29
AI Technical Summary
Existing methods for synthesizing naphthoquinone compounds suffer from environmental pollution, high production costs, difficulty in recovering precious metal catalysts, and difficulty in obtaining raw materials. In particular, methods using 2-methylnaphthalene as a raw material pose safety risks and are costly.
Using a Co-based catalyst under mild liquid-phase conditions and molecular oxygen as an oxidant, naphthyl aromatic hydrocarbons are selectively oxidized to naphthoquinone compounds in the presence of aliphatic aldehydes or aliphatic ethers. The specific steps include adding the catalyst, naphthyl aromatic hydrocarbon, aliphatic aldehyde or aliphatic ether, and molecular oxygen to an organic solvent and carrying out a constant-temperature stirring reaction.
It achieves a conversion rate of over 80% for naphthyl aromatics and a selectivity of over 75% for naphthoquinone compounds. The reaction is safe and low-cost, avoiding the use of high-concentration hydrogen peroxide and the difficulties in recovering precious metal catalysts.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of fine chemicals, and specifically relates to a new method for preparing naphthoquinone compounds by using naphthyl aromatic hydrocarbons as raw materials and molecular oxygen as an oxidant through liquid-phase catalytic selective oxidation reaction. Background Technology
[0002] Currently, naphthoquinones are widely distributed in plants, animals, and bacteria in nature, and have important applications in medicine, agriculture, animal husbandry, and many other fields. For example, 2-methyl-1,4-naphthoquinone is a key intermediate in the synthesis of vitamins K1 and K4, and it can also participate in the synthesis of clotting factors in the liver, thus being used as an anti-hemorrhagic drug and an additive in young animal feed. Furthermore, due to its unique physiological activity, 2-methyl-1,4-naphthoquinone can also be used in anti-tumor drug research and as a plant growth regulator. The efficient preparation of naphthoquinones has significant application potential.
[0003] Taking 2-methyl-1,4-naphthoquinone as an example, the main industrial methods for synthesizing 2-methyl-1,4-naphthoquinone are the 2-methylnaphthalene chromic anhydride oxidation method and the toluene-butadiene cyclization method. Both methods use chromium-based oxidants, generating large amounts of chromium-containing wastewater during production, placing a significant burden on environmental protection. The harmless treatment of this wastewater also greatly increases production costs. Currently, research on the green preparation of 2-methyl-1,4-naphthoquinone mainly falls into two categories: one uses 2-methylnaphthalene as a raw material and hydrogen peroxide as an oxidant; the other uses 2-methylnaphthalene derivatives as raw materials and hydrogen peroxide or oxygen as an oxidant. For example, Wolfgang A. Herrmann et al. disclosed a method for the catalytic oxidation of 2-methylnaphthalene to 2-methyl-1,4-naphthoquinone using methylrhenium trioxide as a catalyst, 85% hydrogen peroxide aqueous solution as an oxidant, and acetic anhydride as an auxiliary agent. The yield of the main product, 2-methyl-1,4-naphthoquinone, can reach 52%. However, the use of high-concentration hydrogen peroxide solution increases the production risk, and the use of the precious metal rhenium increases the production cost (Journal of Molecular Catalysis A: Chemical, 1999, 138, 115–121). Matthias Beller et al. synthesized a ruthenium-based complex as a catalyst to prepare 2-methyl-1,4-naphthoquinone by oxidizing 2-methylnaphthalene with hydrogen peroxide. The highest yield of 2-methyl-1,4-naphthoquinone was 51%, and the main byproducts included 6-methyl-1,4-naphthoquinone. However, this type of Ru homogeneous complex catalytic system uses precious metals and is difficult to recover (Advanced Synthesis & Catalysis, 2007, 349, 303–308). Besides using 2-methylnaphthalene as a starting material, Oxana A. Kholdeeva et al. reported a method for synthesizing 2-methyl-1,4-naphthoquinone from 2-methyl-1-naphthol, using hydrogen peroxide as an oxidant and a titanosilicate (Ti-MMM-2) catalyst (Journal of Catalysis, 2005, 236, 62-68). However, the inexpensive availability of 2-methyl-1-naphthol limits the practical application of this method. Didier Villemind et al. reported a method for synthesizing 2-methyl-1,4-naphthoquinone from 2-methyl-1,4-naphthodiol, using iron phthalocyanine supported on zirconium phosphate as a catalyst and oxygen as an oxidant, achieving a yield of 80% (Synthetic Communications, 2022, 32, 1501-1515). However, the 2-methyl-1,4-naphthodiol used in this method is also complex to synthesize and difficult to obtain.In summary, current methods for synthesizing 2-methyl-1,4-naphthoquinone still face numerous challenges. For example, the transportation and storage of high-concentration hydrogen peroxide pose significant safety risks; the recovery of precious metal catalysts such as rhenium and ruthenium is difficult and costly; and 2-methylnaphthalene derivatives (such as naphthol) are difficult to obtain cheaply as raw materials. Therefore, developing an environmentally friendly and efficient synthetic process for naphthoquinone compounds remains a crucial issue that urgently needs to be addressed.
[0004] This invention uses molecular oxygen as the oxygen source to catalytically and selectively oxidize naphthyl aromatic hydrocarbons to naphthoquinone compounds under mild liquid-phase oxidation reaction conditions, providing a new method for the green production of naphthoquinone compounds. Summary of the Invention
[0005] To address the above problems, this invention provides a method for preparing naphthoquinone compounds by liquid-phase catalytic oxidation of naphthyl aromatic hydrocarbons with molecular oxygen using a Co-based catalyst in the presence of aliphatic aldehydes or aliphatic ethers. This method is a novel approach for preparing naphthoquinone compounds under mild conditions using naphthyl aromatic hydrocarbons and their derivatives as raw materials and molecular oxygen as the oxidant.
[0006] To achieve the above objectives, the specific technical solution of the present invention is as follows:
[0007] A method for the selective oxidation of naphthyl aromatic hydrocarbons to naphthoquinone compounds using molecular oxygen via catalysis is disclosed. This method involves the liquid-phase selective oxidation of naphthyl aromatic hydrocarbons to naphthoquinone compounds using a cobalt-based catalyst in the presence of aliphatic aldehydes or ethers. The method uses naphthyl aromatic hydrocarbons as raw materials and molecular oxygen as the oxygen source, selectively oxidizing the hydrocarbons to naphthoquinone compounds in an organic solvent via liquid-phase catalysis in the presence of aliphatic aldehydes or ethers. The method provided by this invention achieves a naphthyl aromatic hydrocarbon conversion rate of over 80% and a naphthoquinone compound selectivity of over 75%. Specifically, it includes the following steps:
[0008] A catalyst, naphthyl aromatic hydrocarbon feedstock, aliphatic aldehydes or ethers, and an organic solvent are added to a high-pressure reactor. Using molecular oxygen as the oxidant, the reactor is heated and stirred at a constant temperature between 80-150°C for 0.2-12 hours. The reaction solution is then separated to obtain naphthoquinone compounds. In this step, aliphatic aldehydes and ethers can generate reactive oxygen species in situ with oxygen during the reaction, which oxidize the naphthyl aromatic hydrocarbon to naphthoquinone compounds under the catalysis of the catalyst.
[0009] Furthermore, the amount of catalyst fed is 1-20 wt% of the amount of naphthyl aromatic hydrocarbon fed; the amount of organic solvent used is 5-30 times the mass of naphthyl aromatic hydrocarbon; and the amount of aliphatic aldehyde or aliphatic ether used is 1-6 times the molar amount of naphthyl aromatic hydrocarbon substrate.
[0010] Furthermore, the naphthyl aromatic hydrocarbons and naphthoquinone compounds have the structures shown in the following reaction formulas:
[0011]
[0012] Wherein, R1 is one or more of hydrogen, alkyl, halogen, -NO2, methoxy, ethoxy, cyano, amino, acetoxy, or acetamino; R2 is one or more of hydrogen, alkyl, halogen, -NO2, methoxy, ethoxy, cyano, amino, acetoxy, or acetamino; R3 is one or more of hydrogen, alkyl, halogen, -NO2, methoxy, ethoxy, cyano, amino, acetoxy, or acetamino; R1–R3 may be the same or different.
[0013] Furthermore, the organic solvent used in the catalytic oxidation reaction is one or more of formic acid, acetic acid, butyric acid, and acetic anhydride.
[0014] Furthermore, the molecular oxygen in the catalytic oxidation reaction comes from air, oxygen gas, or a gas containing oxygen. The partial pressure of oxygen is 0.2-0.8 MPa.
[0015] Furthermore, the aliphatic aldehyde in the catalytic reaction is one or more of formaldehyde, acetaldehyde, metaldehyde, n-butyraldehyde, and isobutyraldehyde; the aliphatic ether in the catalytic reaction is one or more of dipropylene glycol dimethyl ether, diethylene glycol dimethyl ether, and 1,4-dioxane.
[0016] Furthermore, the catalyst is one or more of cobalt tetroxide, cobalt(II) oxide, cobalt sulfate, cobalt acetate, cobalt nitrate, cobalt chloride, cobalt carbonate, and Co-NC composite material.
[0017] Furthermore, the preparation steps of the Co-NC composite catalyst are as follows:
[0018] First, cobalt acetate and 1,10-phenanthroline are dissolved in anhydrous ethanol to obtain a mixed solution, wherein the molar ratio of cobalt acetate to 1,10-phenanthroline is 1:1 to 1:5. Second, the mixed solution is heated and stirred at 50-110℃ for 1.5-10h, cooled to room temperature, and the solvent is removed by rotary evaporation under reduced pressure. After vacuum drying, the resulting precursor is thoroughly ground. Finally, it is pyrolyzed at 300-900℃ in a nitrogen atmosphere for 0.5-8h, cooled to room temperature, and thoroughly ground to obtain the Co-NC composite material.
[0019] The beneficial effects of this invention and its differences from existing research are as follows:
[0020] (1) This invention uses cobalt-based catalytic materials and adds aliphatic aldehydes or aliphatic ethers to achieve liquid-phase catalytic oxidation of naphthyl aromatic hydrocarbons to obtain the corresponding naphthoquinone compounds. It has strong practicality and broad application prospects.
[0021] (2) Unlike the reaction process of oxidizing 2-methylnaphthalene or its derivatives with hydrogen peroxide as an oxidant, the present invention uses oxygen as an oxidant, which makes the reaction safer and the production cost lower.
[0022] (3) Although the catalytic oxidation system with aliphatic aldehydes as additives has been used to synthesize terephthalic acid from p-xylene, the reaction process mainly involves the oxidation of the side chain methyl group; while in the oxidation system reported in this invention, the naphthalene ring undergoes preferential oxidation to obtain naphthoquinone compounds, with a low degree of side chain alkyl oxidation. This is because the two have different molecular structures, and the electron distribution inside the naphthyl aromatic molecule is uneven, making it more prone to ring oxidation reactions than benzene compounds. Detailed Implementation
[0023] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the following description.
[0024] Example 1
[0025] 1. Preparation of the catalyst Co-NC(A)
[0026] The Co-NC catalyst was prepared using a molar ratio of cobalt acetate to 1,10-phenanthroline (1:2): 3 mmol of cobalt acetate was mixed with 6 mmol of 1,10-phenanthroline, and 150 mL of ethanol was added. The mixture was heated to 100 °C and stirred for 4 h. After cooling to room temperature, the ethanol was removed by rotary evaporation under reduced pressure. The mixture was then vacuum dried at 60 °C for 12 h. After thorough grinding, the mixture was heat-treated at 450 °C under a nitrogen atmosphere for 1.5 h and then cooled to obtain the Co-NC catalyst, denoted as catalyst Co-NC(A).
[0027] 2.1 Synthesis of Naphthoquinone
[0028] 2 mmol naphthalene, 5 wt% catalyst A, 4 mL acetic acid, and 6 mmol paraldehyde were added to a reactor, which was then purged with 0.4 MPa oxygen and heated to 90 °C. The mixture was stirred for 8 h. Samples were taken for quantitative analysis of the product. The conversion rate of naphthalene was 88%, and the selectivity for 1,4-naphthoquinone was 87%. The reaction results are shown in Table 1.
[0029] In this embodiment, the specific structures of the reaction formulas for the raw material naphthyl aromatic hydrocarbon and the product naphthoquinone compound are as follows:
[0030]
[0031] R1, R2, and R3 are all hydrogen.
[0032] Example 2
[0033] 1. Preparation of the catalyst Co-NC(B)
[0034] The Co-NC catalyst was prepared using a molar ratio of cobalt acetate to 1,10-phenanthroline (1:4): 3 mmol of cobalt acetate was mixed with 12 mmol of 1,10-phenanthroline, and 150 mL of ethanol was added. The mixture was heated to 110 °C and stirred for 2 h, then cooled to room temperature. The ethanol was removed by rotary evaporation, and the mixture was vacuum dried at 60 °C for 12 h. The mixture was then thoroughly ground and heat-treated at 300 °C under a nitrogen atmosphere for 8 h, followed by cooling to obtain the Co-NC catalyst, denoted as catalyst Co-NC(B).
[0035] Synthesis of 2,2-methyl-1,4-naphthoquinone
[0036] 2 mmol of 2-methylnaphthalene, 1 wt% catalyst B, 6 mL of butyric acid, and 8 mmol of paraldehyde were added to a reaction vessel, which was then purged with 0.6 MPa of oxygen. The mixture was heated to 90 °C and stirred for 9 h. Samples were taken for quantitative analysis of the product. The conversion rate of 2-methylnaphthalene was 89%, and the selectivity for 2-methyl-1,4-naphthoquinone was 84%. The reaction results are shown in Table 1.
[0037] In this embodiment, the specific structures of the reaction formulas for the raw material naphthyl aromatic hydrocarbon and the product naphthoquinone compound are as follows:
[0038]
[0039] Where R1 is methyl; R2 is hydrogen; and R3 is hydrogen.
[0040] Example 3
[0041] 1. Preparation of the catalyst Co-NC(C)
[0042] The Co-NC catalyst was prepared using a molar ratio of cobalt acetate and 1,10-phenanthroline (1:1): 3 mmol of cobalt acetate and 3 mmol of 1,10-phenanthroline were mixed, and 100 mL of ethanol was added. The mixture was heated to 50 °C and stirred for 10 h. After cooling to room temperature, the ethanol was removed by rotary evaporation, and the mixture was vacuum dried at 60 °C for 12 h. The mixture was then thoroughly ground and heat-treated at 900 °C under a nitrogen atmosphere for 0.5 h before cooling to obtain the Co-NC catalyst, denoted as catalyst Co-NC(C)C.
[0043] 2,5-Acetoxy-1,4-Naphthoquinone
[0044] 2 mmol of 1-acetoxynaphthalene, 3 wt% catalyst D, 4 mL of acetic acid, and 6 mmol of dipropylene glycol dimethyl ether were added to a reaction vessel, which was then purged with 0.4 MPa of oxygen and heated to 100 °C. The mixture was stirred for 8 h. Samples were taken for quantitative analysis of the product. The conversion rate of 1-acetoxynaphthalene was 86%, and the selectivity for 5-acetoxy-1,4-naphthoquinone was 83%. The reaction results are shown in Table 1.
[0045] In this embodiment, the specific structures of the reaction formulas for the raw material naphthyl aromatic hydrocarbon and the product naphthoquinone compound are as follows:
[0046]
[0047] Where R1 is hydrogen; R2 is hydrogen; and R3 is acetoxy.
[0048] Example 4
[0049] Synthesis of 2,3-dicyano-1,4-naphthoquinone
[0050] 2 mmol naphthalene, 10 wt% cobalt acetate, 5 mL acetic anhydride, and 8 mmol paraldehyde were added to a reaction vessel, purged with 0.5 MPa oxygen, heated to 120 °C, and stirred for 8 h. Samples were taken for quantitative analysis of the product. The conversion rate of 2,3-dicyanonaphthalene was 80%, and the selectivity of 2,3-dicyano-1,4-naphthoquinone was 79%. The reaction results are shown in Table 1.
[0051] In this embodiment, the specific structures of the reaction formulas for the raw material naphthyl aromatic hydrocarbon and the product naphthoquinone compound are as follows:
[0052]
[0053] Where R1 is cyano; R2 is cyano; and R3 is hydrogen.
[0054] Example 5
[0055] Synthesis of 2-amino-1,4-naphthoquinone
[0056] 3 mmol of 2-nitronaphthalene, 15 wt% cobalt sulfate, 5 mL of formic acid, and 6 mmol of formaldehyde were added to a reaction vessel, which was then purged with 0.5 MPa of oxygen. The mixture was heated to 150 °C and stirred for 10 h. Samples were taken for quantitative analysis of the product. The conversion rate of 2-aminonaphthalene was 84%, and the selectivity of 2-amino-1,4-naphthoquinone was 80%. The reaction results are shown in Table 1.
[0057] In this embodiment, the specific structures of the reaction formulas for the raw material naphthyl aromatic hydrocarbon and the product naphthoquinone compound are as follows:
[0058]
[0059] Wherein, R1 is an amino group; R2 is hydrogen; and R3 is hydrogen.
[0060] Example 6
[0061] Synthesis of 2-chloro-1,4-naphthoquinone
[0062] 1 mmol of 2-chloronaphthalene, 20 wt% cobalt tetroxide, 6 mL of acetic acid, and 3 mmol of 1,4-dioxane were added to a reaction vessel, which was then purged with 0.5 MPa of oxygen and heated to 110 °C. The mixture was stirred for 10 h. Samples were taken for quantitative analysis of the product. The conversion rate of 2-chloronaphthalene was 81%, and the selectivity for 2-chloro-1,4-naphthoquinone was 80%. The reaction results are shown in Table 1.
[0063] In this embodiment, the specific structures of the reaction formulas for the raw material naphthyl aromatic hydrocarbon and the product naphthoquinone compound are as follows:
[0064]
[0065] Where R1 is chlorine; R2 is hydrogen; and R3 is hydrogen.
[0066] Example 7
[0067] Synthesis of 2-methoxy-1,4-naphthoquinone
[0068] 4 mmol of 2-methoxynaphthalene, 15 wt% cobalt(II) oxide, 8 mL of acetic acid, and 4 mmol of diethylene glycol dimethyl ether were added to a reaction vessel, which was then purged with 0.7 MPa of oxygen and heated to 140 °C. The mixture was stirred for 8 h. Samples were taken for quantitative analysis of the product. The conversion rate of 2-methoxynaphthalene was 87%, and the selectivity for 2-methoxy-1,4-naphthoquinone was 85%. The reaction results are shown in Table 1.
[0069] In this embodiment, the specific structures of the reaction formulas for the raw material naphthyl aromatic hydrocarbon and the product naphthoquinone compound are as follows:
[0070]
[0071] Wherein, R1 is methoxy; R2 is hydrogen; and R3 is hydrogen.
[0072] Example 8
[0073] Synthesis of 2-bromo-1,4-naphthoquinone
[0074] 3 mmol of 2-bromonaphthalene, 10 wt% cobalt chloride, 6 mL of acetic acid, and 6 mmol of n-butyraldehyde were added to a reaction vessel, purged with 0.8 MPa of oxygen, heated to 120 °C, and stirred for 12 h. Samples were taken for quantitative analysis of the product. The conversion rate of 2-bromonaphthalene was 82%, and the selectivity for 2-bromo-1,4-naphthoquinone was 81%. The reaction results are shown in Table 1.
[0075] In this embodiment, the specific structures of the reaction formulas for the raw material naphthyl aromatic hydrocarbon and the product naphthoquinone compound are as follows:
[0076]
[0077] Where R1 is bromine; R2 is hydrogen; and R3 is hydrogen.
[0078] Example 9
[0079] Synthesis of 2,6-diethoxy-1,4-naphthoquinone
[0080] 3 mmol of 2,6-diacetoxynaphthalene, 20 wt% cobalt carbonate, 10 mL of acetic acid, 3 mmol of acetaldehyde, and 3 mmol of isobutyraldehyde were added to a reaction vessel, purged with 0.2 MPa of oxygen, heated to 120 °C, and stirred for 8 h. Samples were taken for quantitative analysis of the product. The conversion rate of 2,6-diacetoxynaphthalene was 83%, and the selectivity for 2,6-diethoxy-1,4-naphthoquinone was 82%. The reaction results are shown in Table 1.
[0081] In this embodiment, the specific structures of the reaction formulas for the raw material naphthyl aromatic hydrocarbon and the product naphthoquinone compound are as follows:
[0082]
[0083] Wherein, R1 is ethoxy; R2 is hydrogen; and R3 is ethoxy.
[0084] Table 1. Composition of different catalysts and additives and the results of each reaction.
[0085] serial number catalyst Fatty aldehydes or fatty ethers Naphthyl aromatic hydrocarbon conversion rate (%) Selectivity of naphthoquinone compounds (%) Example 1 Co-NC(A) Methanaldehyde 88 87 Example 2 Co-NC(B) Methanaldehyde 89 84 Example 3 Co-NC(C) Dipropylene glycol dimethyl ether 86 88 Example 4 Cobalt acetate Methanaldehyde 80 79 Example 5 Cobalt sulfate formaldehyde 84 80 Example 6 Cobalt tetroxide 1,4-Dioxane 81 80 Example 7 Cobalt(II) oxide Diethylene glycol dimethyl ether 87 85 Example 8 cobalt chloride n-Butyraldehyde 82 81 Example 9 Cobalt carbonate Acetaldehyde and isobutyraldehyde 83 82
[0086] The method provided by this invention achieves a naphthyl aromatic hydrocarbon conversion rate of over 80% and a selectivity of over 75% for naphthoquinone compounds.
[0087] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, not limiting words. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.
Claims
1. A method for preparing naphthoquinone compounds by selective oxidation of naphthyl aromatic hydrocarbons by catalytic molecular oxygen, characterized in that, The method uses naphthyl aromatic hydrocarbons as raw materials and molecular oxygen as the oxygen source. In the presence of aliphatic aldehydes or aliphatic ethers, naphthyl aromatic hydrocarbons are selectively oxidized to naphthoquinone compounds in an organic solvent via liquid-phase catalysis.
2. The method for preparing naphthoquinone compounds by selective oxidation of naphthyl aromatic hydrocarbons by catalytic molecular oxygen according to claim 1, characterized in that, The method includes the following steps: A catalyst, naphthyl aromatic hydrocarbon raw material, aliphatic aldehyde or aliphatic ether, and organic solvent are added to a high-pressure reactor. Molecular oxygen is used as an oxidant, and the reactor is heated and stirred at a constant temperature between 80-150℃ for 0.2-12 hours. The reaction solution is then separated to obtain naphthoquinone compounds.
3. The method for preparing naphthoquinone compounds by selective oxidation of naphthyl aromatic hydrocarbons by catalytic molecular oxygen according to claim 1, characterized in that, The method achieves a naphthyl aromatic hydrocarbon conversion rate of over 80% and a selectivity of over 75% for naphthoquinone compounds.
4. The method for preparing naphthoquinone compounds by selective oxidation of naphthyl aromatic hydrocarbons by catalytic molecular oxygen according to claim 1, characterized in that, The catalyst feed amount is 1-20 wt% of the naphthyl aromatic hydrocarbon feed amount; the organic solvent amount is 5-30 times the mass of the naphthyl aromatic hydrocarbon; the aliphatic aldehyde or aliphatic ether amount is 1-6 times the molar amount of the naphthyl aromatic hydrocarbon substrate.
5. The method for preparing naphthoquinone compounds by selective oxidation of naphthyl aromatic hydrocarbons by catalytic molecular oxygen according to claim 1, characterized in that, The starting material, naphthyl aromatic hydrocarbon, and the product, naphthoquinone compounds, have the structures shown in the following reaction formulas: Wherein, R1 is one or more of hydrogen, alkyl, halogen, -NO2, methoxy, ethoxy, cyano, amino, acetoxy, or acetamino; R2 is one or more of hydrogen, alkyl, halogen, -NO2, methoxy, ethoxy, cyano, amino, acetoxy, or acetamino; R3 is one or more of hydrogen, alkyl, halogen, -NO2, methoxy, ethoxy, cyano, amino, acetoxy, or acetamino; R1–R3 may be the same or different.
6. The method for preparing naphthoquinone compounds by selective oxidation of naphthyl aromatic hydrocarbons by catalytic molecular oxygen according to claim 1, characterized in that, The organic solvent used in the catalytic oxidation reaction is one or more of formic acid, acetic acid, butyric acid, and acetic anhydride; the molecular oxygen in the catalytic oxidation reaction comes from air, oxygen gas, or a gas containing oxygen.
7. The method for preparing naphthoquinone compounds by selective oxidation of naphthyl aromatic hydrocarbons by catalytic molecular oxygen according to claim 6, characterized in that, The partial pressure of oxygen in the catalytic oxidation reaction is 0.2-0.8 MPa.
8. The method for preparing naphthoquinone compounds by selective oxidation of naphthyl aromatic hydrocarbons by catalytic molecular oxygen according to claim 1, characterized in that, The aliphatic aldehyde in the catalytic reaction is one or more of formaldehyde, acetaldehyde, triacetaldehyde, n-butyraldehyde, and isobutyraldehyde; the aliphatic ether in the catalytic reaction is one or more of dipropylene glycol dimethyl ether, diethylene glycol dimethyl ether, and 1,4-dioxane.
9. The method for preparing naphthoquinone compounds by selective oxidation of naphthyl aromatic hydrocarbons by catalytic molecular oxygen according to claim 1, characterized in that, The catalyst is one or more of cobalt tetroxide, cobalt(II) oxide, cobalt sulfate, cobalt acetate, cobalt nitrate, cobalt chloride, cobalt carbonate, and Co-NC composite material.
10. The method for preparing naphthoquinone compounds by selective oxidation of naphthyl aromatic hydrocarbons by catalytic molecular oxygen according to claim 1, characterized in that, The preparation steps of the Co-NC composite catalyst are as follows: First, cobalt acetate and 1,10-phenanthroline are dissolved in anhydrous ethanol to obtain a mixed solution, wherein the molar ratio of cobalt acetate to 1,10-phenanthroline is 1:1-1:
5. Second, the mixed solution is heated and stirred at 50-110℃ for 1.5-10h, cooled to room temperature, the solvent is removed, and the precursor is dried under vacuum and then thoroughly ground. Finally, the precursor is pyrolyzed at 300-900℃ in a nitrogen atmosphere for 0.5-8h, cooled to room temperature, and thoroughly ground to obtain the Co-NC composite material.