Method for preparing 1-acenaphthenone through visible light catalysis

Abstract

The invention provides a method for preparing 1-acenaphthenone through visible light catalysis, and belongs to the technical field of organic synthesis and photocatalysis. According to the method, dihydroacenaphthene is taken as a starting material, in a mixed solvent system, self-made carbon quantum dots are taken as a photocatalyst, oxygen is taken as a green oxidant, and an oxidation reaction is realized under the condition of visible light irradiation, so that the target product 1-acenaphthone is obtained. The carbon quantum dots used in the invention have excellent light absorption and electron transfer capabilities, can effectively promote oxygen activation, and realize selective oxidation of a substrate; meanwhile, oxygen serving as an oxidizing agent is wide in source and free of pollution, and safety risks and environmental problems caused by traditional peroxides or strong oxidants are avoided. The reaction conditions are mild, the operation process is simple, the high-pressure or high-temperature condition is not needed, and the reaction can be carried out under the normal-pressure oxygen condition; the solvent source is cheap and easy to obtain, the reaction post-treatment is convenient, byproducts are few, and the whole is green and environment-friendly.

Description

Technical Field

[0001] This invention relates to the fields of organic synthesis and photocatalysis, and in particular to a method for preparing 1-acenaphthene using visible light catalysis. Background Technology

[0002] 1-Anaphthene is an important class of polycyclic aromatic ketones, widely used in the synthesis of fine chemicals, pharmaceutical intermediates, and organic functional materials. It serves as a key structural unit for various substituted acenaphthene compounds, aromatic ligands, and heterocyclic compounds. Traditional methods for preparing 1-acenaphthene typically use dihydroacenaphthene as a raw material, employing dichromates, permanganates, or high-valent metal oxidants for oxidation. However, these methods generally suffer from problems such as high toxicity of the oxidants, high dosage requirements, numerous byproducts, and severe environmental pollution. Furthermore, they exhibit low product selectivity, easily generating peroxidation or further ring-opening oxidation byproducts, leading to unstable yields and hindering industrial scale-up and green production. In addition, some methods require precious metal catalysts or high-temperature, high-pressure conditions, resulting in demanding equipment and high costs. Therefore, developing a novel method for the selective oxidation of dihydroacenaphthene under mild conditions, while also being green, safe, and efficient, has become a key research focus and challenge in related fields, possessing significant practical application value.

[0003] Patent CN102584557B describes a method using dihydroacenaphthene as a raw material, cuprous chloride (CuCl) as a catalyst, and sodium chlorite (NaCl) in an aqueous / organic two-phase system. This invention relates to a method for preparing acenaphthene using chlorite oxidants. The advantages of this method are that the reaction conditions are mild, the operation is easy, and it yields a high rate, making it suitable for scale-up production. The inventors emphasized the yield and process simplicity. However, there are also significant disadvantages: chlorite oxidants may generate highly reactive oxides (such as Cl-) with strong oxidizing properties and safety risks when exothermic or coexisting with organic matter. Special safety controls and exhaust gas treatment are required during industrial scale-up. In addition, copper (I) salts are easily oxidized / precipitated in water and organic phases, and catalyst recovery and treatment of copper-containing waste liquid will increase costs and environmental burden.

[0004] Patent US1439500A reports a process for obtaining partial oxidation products of acenaphthene compounds through high-temperature contact of air (or oxygen) on the catalyst surface (a historic catalytic gas-phase oxidation route). The advantages are extremely simple raw materials and oxidants (air / oxygen), no need for complex oxidant addition, and the ability to use a continuous gas-phase contactor, theoretically facilitating scale-up. The disadvantages are also obvious: this route typically requires high temperatures (hundreds of degrees Celsius) or strong contact activation conditions, resulting in poor selectivity and a tendency to produce over-oxidation or further ring-opening products; simultaneously, high-temperature / gas-phase oxidation places high demands on materials and safety management, hindering the high selectivity of the target product, and incurring heavy energy consumption and byproduct handling burdens. For this patent seeking a "mild, green, visible light / room temperature condition" route, this traditional gas-phase catalytic oxidation is not ideal.

[0005] Patent CN103936648A (2,2-bis(1H-indole-3-yl)-2H-acenaphthyl-1-one compounds and their preparation method) does not follow the typical route of directly oxidizing acenaphthylene to 1-acenaphthylone. Instead, it involves the addition / coupling of acenaphthylene or other pre-oxygenated acenaphthylene derivatives with indoles, yielding high-yield acenaphthyl-1-one derivatives in the presence of sulfonic acid catalysts. Its advantages lie in providing high yields (high yields and short reaction times reported in the literature / specification) and the reproducibility of the process. In comparison, its limitation lies in the fact that it does not directly solve the problem of green oxidation from inexpensive and unoxidized dihydroacenaphthene to 1-acenaphthene: this route relies on oxidized or pretreated raw materials (such as acenaphthene quinone) or strong acid catalytic conditions, and cannot replace a process of "direct in-situ oxidation of dihydroacenaphthene under mild, heavy metal-free / strong oxidant-free conditions"; moreover, the corrosion resistance of the acid catalytic system during scale-up and the treatment of acidic waste liquid also need to be considered.

[0006] Therefore, there is an urgent need for an environmentally friendly, reagent-simple, and safe method for synthesizing acenaphthene. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing 1-acenaphthene using visible light catalysis, in order to solve the above-mentioned technical problems.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing 1-acenaphthene using visible light photocatalysis, comprising the following steps: 1) Add a mixed solvent of ethanol and acetonitrile to dihydroacenaphthene and carbon quantum dot photocatalyst to form a homogeneous reaction system; 2) Under oxygen atmosphere and visible light irradiation, the reaction system was subjected to photocatalytic oxidation reaction, the solvent was removed by rotary evaporation of the reaction solution, and purified 1-acenaphthene was obtained after separation and purification. The mass ratio of dihydroacenaphthene to carbon quantum dot photocatalyst is 7.5~20:1.

[0009] Furthermore, the carbon quantum dot photocatalyst comprises one or more of citric acid-derived carbon quantum dots, glucose-derived carbon quantum dots, and urea-derived carbon quantum dots.

[0010] Furthermore, the volume ratio of ethanol to acetonitrile is 1~3:1~3.

[0011] Furthermore, the oxygen flow rate is 30~80 mL / min.

[0012] Furthermore, the wavelength of the visible light is 450~460nm.

[0013] Furthermore, the temperature of the photocatalytic oxidation reaction is 25~40℃, and the time of the photocatalytic oxidation reaction is 8~14h.

[0014] The beneficial effects of this invention are: This invention uses dihydroacenaphthene as a starting material, employs self-made carbon quantum dots as a photocatalyst, and oxygen as an oxidant to achieve the selective oxidation of dihydroacenaphthene in a mixed solvent of ethanol and acetonitrile under visible light irradiation at 455-460 nm. By maintaining an oxygen atmosphere through three vacuum-oxygenation cycles followed by the insertion of an oxygen ball, the oxygen activation efficiency is effectively improved, allowing for the gentle conversion of dihydroacenaphthene to 1-acenaphthene. After the reaction, the solvent is removed by rotary evaporation, and the product is purified by silica gel column chromatography to obtain high-purity 1-acenaphthene.

[0015] The synthesis method of this invention is simple in steps, and the carbon quantum dots used as catalyst are readily available and easy to prepare. It eliminates the need for precious metal catalysts and strong oxidants, reducing the environmental pollution and safety risks that may arise in traditional methods. The reaction conditions of this invention are mild, requiring no high temperature or high pressure, and the solvents are all conventional organic solvents. The operation is safe and environmentally friendly, and the post-processing is simple, making it suitable for laboratory synthesis and further industrial scale-up applications.

[0016] This invention uses oxygen as the sole oxidant, eliminating the need for additional highly toxic or highly reactive oxidation systems, significantly reducing costs while improving the greenness of the reaction. Therefore, this invention offers significant advantages in green synthesis, selective control, and sustainable catalysis. Attached Figure Description

[0017] Figure 1 The 1H NMR spectrum of 1-acenaphthene prepared in Example 1; Figure 2 The image shows the carbon NMR spectrum of 1-acenaphthene prepared in Example 1. Detailed Implementation

[0018] This invention provides a method for preparing 1-acenaphthene using visible light photocatalysis, comprising the following steps: 1) Add a mixed solvent of ethanol and acetonitrile to dihydroacenaphthene and carbon quantum dot photocatalyst to form a homogeneous reaction system; 2) Under oxygen atmosphere and visible light irradiation, the reaction system was subjected to photocatalytic oxidation reaction, the solvent was removed by rotary evaporation of the reaction solution, and purified 1-acenaphthene was obtained after separation and purification. The mass ratio of dihydroacenaphthene to carbon quantum dot photocatalyst is 7.5~20:1, preferably 10~15:1, and more preferably 15:1.

[0019] In this invention, the carbon quantum dot photocatalyst comprises one or more of citric acid-derived carbon quantum dots, glucose-derived carbon quantum dots, and urea-derived carbon quantum dots, preferably citric acid-derived carbon quantum dots.

[0020] In this invention, the volume ratio of ethanol to acetonitrile is 1~3:1~3, preferably 1:1.

[0021] In this invention, the oxygen flow rate is 30-80 mL / min, preferably 40-60 mL / min, and more preferably 50 mL / min.

[0022] In this invention, the wavelength of the visible light is 450~460nm, preferably 455~460nm.

[0023] In this invention, the temperature of the photocatalytic oxidation reaction is 25-40°C, preferably 30-35°C; the time of the photocatalytic oxidation reaction is 8-14 hours, preferably 9-13 hours, and more preferably 10-12 hours. Unless otherwise specified, all raw materials and reagents used in this invention are those skilled in the art.

[0024] Familiar commercially available products.

[0025] In this invention, a mixed solvent of ethanol and acetonitrile is added to a carbon quantum dot catalyst, and after it is fully dissolved, dihydroacenaphthene is added to form a mixed solution for the reaction.

[0026] In this invention, the oxygen atmosphere is formed by evacuating the vacuum and passing oxygen through it three times, and then inserting an oxygen ball.

[0027] The reaction formula for the preparation of 1-acenaphthene in this invention is as follows: .

[0028] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0029] Example 1

[0030] Dihydroacenaphthene (1.0 g, 6.49 mmol), citric acid-derived carbon quantum dot photocatalyst (0.1 g), and a mixed solvent of ethanol (35 mL) and acetonitrile (35 mL) were added to a reaction vessel and stirred thoroughly to form a homogeneous reaction solution. The reaction solution was then passed through a photofluidic reactor at a flow rate of 5 mL / min, while oxygen was simultaneously introduced at a flow rate of 50 mL / min to maintain a continuous oxygen atmosphere. The reaction temperature was controlled at 35 °C, and the photocatalytic oxidation reaction was carried out under visible light irradiation at a wavelength of 455–460 nm for 12 hours. After the reaction, the reaction solution was collected, and the solvent was removed by rotary evaporation at 40 °C. The carbon quantum dot catalyst was then removed by diatomaceous earth filtration, followed by separation and purification by silica gel column chromatography using ethyl acetate / petroleum ether (1:4, v / v) as the eluent. The resulting product was 1-acenaphthene, with a yield of 70% and a purity of up to 96%.

[0031] Preparation of citric acid-derived carbon quantum dots: 3.0 g of citric acid and 0.5 g of NaOH were dissolved in 30 mL of deionized water and stirred until a clear solution was obtained. The resulting clear solution was heated in a 750 W microwave reactor for 2.5 minutes. After heating, the deionized water was completely evaporated to obtain a crude carbon quantum dot and NaOH mixed powder. The obtained powder was dissolved in an ethanol solution and then centrifuged at 2000 rpm to remove any excess NaOH and incompletely converted small organic molecules. Finally, carbon quantum dots were obtained by freeze-drying.

[0032] Example 2

[0033] Dihydroacenaphthene (1.0 g, 6.49 mmol), glucose-derived carbon quantum dot photocatalyst (0.08 g), and a mixed solvent of ethanol (35 mL) and acetonitrile (35 mL) were added to the reaction vessel and stirred thoroughly to form a homogeneous reaction solution. The reaction solution was circulated into a photofluidic reactor at a flow rate of 5 mL / min, while oxygen was simultaneously introduced at a flow rate of 50 mL / min to maintain a continuous oxygen atmosphere. The reaction temperature was controlled at 25 °C, and the photocatalytic oxidation reaction was carried out under visible light irradiation at a wavelength of 455–460 nm for 12 hours. After the reaction, the reaction solution was collected, and the solvent was removed by rotary evaporation at 40 °C. Subsequently, the carbon quantum dot catalyst was removed by diatomaceous earth filtration, followed by separation and purification by silica gel column chromatography using ethyl acetate / petroleum ether (1:4, v / v) as the eluent. After processing, 1-acenaphthene product was obtained with a yield of 78% and a purity of up to 99%.

[0034] Preparation of glucose-derived carbon quantum dots: 5.0 g of glucose was weighed and placed in a porcelain crucible, then placed in a muffle furnace and dry-calcined at 300 °C for 2 hours. During the reaction, glucose underwent dehydration condensation and carbonization, gradually changing from white to dark brown, eventually forming a charred solid. The carbonized solid was crushed and dissolved in 50 mL of deionized water, and ultrasonically dispersed for 30 minutes to promote the release of carbon quantum dots. The resulting suspension was filtered through a 0.22 μm filter membrane to remove large carbon particles. The filtrate was then dialyzed (MWCO 3500 Da) to remove small molecule impurities, and finally freeze-dried to obtain glucose-derived carbon quantum dots.

[0035] Example 3

[0036] Dihydroacenaphthene (1.0 g, 6.49 mmol), urea-derived carbon quantum dot photocatalyst (0.05 g), and a mixed solvent of ethanol (35 mL) and acetonitrile (35 mL) were added to a reaction vessel and stirred thoroughly to form a homogeneous reaction solution. The reaction solution was then passed through a photofluidic reactor at a flow rate of 5 mL / min, while oxygen was simultaneously introduced at a flow rate of 60 mL / min to maintain a continuous oxygen atmosphere. The reaction temperature was controlled at 35 °C, and the photocatalytic oxidation reaction was carried out under visible light irradiation at a wavelength of 455–460 nm for 12 hours. After the reaction, the reaction solution was collected, and the solvent was removed by rotary evaporation at 40 °C. Subsequently, the carbon quantum dot catalyst was removed by diatomaceous earth filtration, followed by separation and purification by silica gel column chromatography using ethyl acetate / petroleum ether (1:4, v / v) as the eluent. After processing, 1-acenaphthene product was obtained with a yield of 75% and a purity of up to 98%.

[0037] Preparation of urea-derived carbon quantum dots: 5.0 g of urea was dissolved in 20 mL of deionized water, stirred thoroughly, and then transferred to a 100 mL polytetrafluoroethylene-lined high-pressure reactor. The reactor was placed at 180 °C for hydrothermal reaction for 6 hours. After the reaction, the reactor was allowed to cool naturally to room temperature. The resulting brown reaction solution was filtered through a 0.22 μm filter membrane to remove large particulate impurities. The filtrate was dialyzed against deionized water for 48 hours using a dialysis bag (molecular weight cutoff 3500 Da) to further remove unreacted small molecule impurities. Finally, the dialysate was freeze-dried to obtain purified urea-derived carbon quantum dots.

[0038] Characterization

[0039] Figure 1 The 1H NMR spectrum of 1-acenaphthene prepared in Example 1; Figure 2 The image shows the carbon NMR spectrum of 1-acenaphthene prepared in Example 1.

[0040] Figures 1-2 This demonstrates the successful synthesis of the target product, 1-acenaphthene.

[0041] As can be seen from the above embodiments, this invention provides a method for preparing 1-acenaphthene using visible light photocatalysis. The reaction conditions of this invention are mild, the operation is simple, and it does not require high pressure or high temperature conditions; the reaction can be carried out under normal pressure and oxygen conditions. The solvent is inexpensive and readily available, post-reaction processing is convenient, and there are few byproducts, making the overall process green and environmentally friendly. This method has advantages such as high yield, simple steps, and good safety, making it suitable for large-scale and industrial application.

[0042] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing 1-acenaphthene using visible light photocatalysis, characterized in that, Includes the following steps: 1) Add a mixed solvent of ethanol and acetonitrile to dihydroacenaphthene and carbon quantum dot photocatalyst to form a homogeneous reaction system; 2) Under oxygen atmosphere and visible light irradiation, the reaction system was subjected to photocatalytic oxidation reaction, the solvent was removed by rotary evaporation of the reaction solution, and purified 1-acenaphthene was obtained after separation and purification. The mass ratio of dihydroacenaphthene to carbon quantum dot photocatalyst is 7.5~20:

1.

2. The method for preparing 1-acenaphthene using visible light photocatalysis according to claim 1, characterized in that, The carbon quantum dot photocatalyst comprises one or more of citric acid-derived carbon quantum dots, glucose-derived carbon quantum dots, and urea-derived carbon quantum dots.

3. The method for preparing 1-acenaphthene using visible light photocatalysis according to claim 1 or 2, characterized in that, The volume ratio of ethanol to acetonitrile is 1~3:1~3.

4. The method for preparing 1-acenaphthene using visible light photocatalysis according to claim 3, characterized in that, The oxygen flow rate is 30~80 mL / min.

5. The method for preparing 1-acenaphthene using visible light photocatalysis according to claim 1, 2, or 4, characterized in that, The wavelength of the visible light is 450~460nm.

6. The method for preparing 1-acenaphthene using visible light photocatalysis according to claim 5, characterized in that, The photocatalytic oxidation reaction is carried out at a temperature of 25-40°C for 8-14 hours.

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