Method for catalytically synthesizing aromatic aldehyde and ketone compounds by monatomic photocatalyst

Abstract

The invention provides a method for catalytically synthesizing aromatic aldehyde and ketone compounds by using a monatomic photocatalyst, and belongs to the technical field. The preparation method comprises the following steps: mixing a melem precursor with a metal salt, and carrying out pretreatment and calcination to prepare the melem-based heterocoordinated monatomic photocatalyst. Then, by adopting a strategy of selective oxidation of a photocatalytic C (sp3)-H bond, the aromatic aldehyde or ketone compound is efficiently synthesized through selective oxidation of the C-H bond by taking the aromatic hydrocarbon as shown in the formula I as a raw material under the conditions of a monatomic photocatalyst and visible light illumination. The catalyst prepared by the method is simple to prepare and low in price, can be used for various functionalized substrates, and keeps good reaction selectivity and efficiency; besides, the photocatalytic oxidation technology of the method is simple to operate and can be amplified to 200 mmol substrate scale, the reaction efficiency is still kept stable, and the method has great industrial application potential.

Description

Technical Field

[0001] This invention relates to the fields of catalytic material preparation and organic synthesis technology, specifically to a method for the synthesis of aromatic aldehydes and ketones using a single-atom photocatalyst. Background Technology

[0002] Aromatic aldehydes are crucial intermediates in the preparation of various fine chemicals, including fragrances, dyes, pharmaceuticals, and food additives, with a huge market demand. Traditional preparation methods for these chemicals typically involve the chlorination-hydrolysis process of methyl aromatics with chlorine gas. The large amounts of chlorine and acid used in this process lead to serious environmental problems. Therefore, developing a green and mild oxidation technology, using methyl aromatics C(sp...)... 3 The selective oxidation of the H-bond to achieve the synthesis of aromatic aldehydes in one step is urgently needed.

[0003] Photocatalytic organic synthesis using sunlight as energy input is an economical, safe, and sustainable synthetic technology. In recent years, heterogeneous photocatalysts with high stability and easy separation have developed rapidly in the field of benzylic CH bond activation. Carbon nitride-based single-atom photocatalysts combine the high atomic utilization and uniformly dispersed active sites of homogeneous catalysts with the advantages of easy separation and recovery of heterogeneous catalysts, showing broad application prospects in the photocatalytic synthesis of aromatic aldehydes. However, research on these catalysts is still in its initial stage. The single M-N4 coordination configuration (M representing a metal) limits the modulation of the electronic structure of the metal center and the activation ability of O2, resulting in a relatively low toluene conversion efficiency (μmol g). -1 h -1 Grade). Melamine (C6N) 10 H6, composed of a triazine structure, is a structural unit of graphitic carbon nitride (g-C3N4). It not only possesses a similar electronic structure and photocatalytic behavior to g-C3N4 but also boasts abundant -NH2 coordination groups. It readily coordinates with metal ions, and its coordination configuration is easily tunable. However, current research on Miller-based photocatalysts is extremely limited, and the construction of their heterocoordinating metal centers is rarely reported. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for the catalytic synthesis of aromatic aldehydes and ketones using a single-atom photocatalyst. This method involves constructing a Miller-amine-based heterocoordination single-atom photocatalyst and rationally controlling the local coordination configuration of the single atom and the O2-to-superoxide radical (O2• - The activation process of ) and the performance of photocatalytic oxidation of CH bonds enable the efficient synthesis of aromatic aldehydes and ketones under visible light.

[0005] To achieve the above objectives, the specific technical solution of the present invention is as follows:

[0006] A method for synthesizing aromatic aldehydes and ketones using a single-atom photocatalyst, comprising using aromatic hydrocarbons including those shown in Formula I as raw materials, reacting under the conditions of a single-atom photocatalyst and visible light irradiation to obtain aromatic aldehydes or ketones shown in Formula II.

[0007] ;

[0008] In the formula, R 1 Including but not limited to one of H, 2-CH3, 3-CH3, 4-CH3, 2-Cl, 3-Cl, 4-Cl, 4-Br, 4-F, 4-MeO, 4-NO2, 4-CF3, 4-COOMe, 4-CN, and 4-CH2CN;

[0009] R 2 Including but not limited to one of H, CH3, CH2CH3, (CH2)2CH3, OCH2CH3, C6H5, (CH2)2C6H5, 4-F-C6H4, and pyridyl.

[0010] This invention employs photocatalysis C(sp) 3 The strategy of selective oxidation of the CH bond, using aromatic hydrocarbons as raw materials, efficiently synthesizes aromatic aldehydes or ketones through selective oxidation of the CH bond under the conditions of a single-atom photocatalyst and visible light irradiation; under visible light irradiation, the electrons (e) in the valence band of the single-atom photocatalyst... - When excited by light, the electron transitions to the conduction band, leaving a hole (h) in the valence band. + Aromatic molecules are bounded by h in the valence band. + Excitation forms a carbopositive radical (R·); simultaneously, electrons in the conduction band... - Reduce O2 to generate O2 ·- R· and O2 ·- Protons combine to form reaction intermediates, which are then converted into aromatic aldehydes or ketones through dehydration. Introducing heterocoordinating elements into the coordination center of the metal monatoms can effectively regulate the electronic structure of the metal center, enhancing its adsorption and activation capacity for O2, and increasing the C(sp) content of aromatic hydrocarbons. 3 Oxidation properties of the -H bond.

[0011] Preferably, the single-atom photocatalyst is a Miller-based heterocoordinating single-atom photocatalyst.

[0012] Preferably, the preparation method of the melamine-based heterocoordination single-atom photocatalyst includes the following steps: mixing a melamine precursor and a metal salt, pretreating and calcining the mixture to obtain the melamine-based heterocoordination single-atom photocatalyst.

[0013] More preferably, the melamine precursor includes, but is not limited to, one of cyanamide, dicyandiamide, thiourea, urea, and melamine.

[0014] More preferably, the cation of the metal salt includes, but is not limited to, the non-noble metal ion NH4+. + Zn 2+ Cu 2+ Ni 2+ Co 2+ Mg 2+ Mn 2+ Ca 2+ Fe 2+ Fe 3+ Cr 3+ Al 3+ W 3+ Ti 4+ V 5+ One of the following; the anion of the metal salt includes, but is not limited to, halide ions, CH3COO - NO3 - SO4 2- One of them.

[0015] More preferably, the mass of the melamine precursor is 1-100 times the mass of the metal salt.

[0016] More preferably, the pretreatment method includes, but is not limited to, one of ball milling, freeze drying, and sol-gel methods.

[0017] More preferably, the calcination temperature is 400-600 ℃.

[0018] More preferably, the calcination atmosphere includes, but is not limited to, one of air, nitrogen, and argon.

[0019] Preferably, the method for synthesizing aromatic aldehydes and ketones by single-atom photocatalysis includes the following steps: placing the aromatic hydrocarbon shown in Formula I and the single-atom photocatalyst in a photoreaction vessel, and reacting under visible light to obtain the aromatic aldehyde or ketone compound shown in Formula II.

[0020] Solvents may be used in the reaction; alternatively, solvents may not be used.

[0021] Preferably, the wavelength of the visible light is 300-800 nm and the power is 3-120 W.

[0022] Preferably, the atmosphere for the reaction is oxygen or air.

[0023] Preferably, the reaction temperature is 20-120 °C; the reaction time is ≥3 h.

[0024] Preferably, the mass ratio of the single-atom photocatalyst to the aromatic hydrocarbon is 0.5-50%.

[0025] Preferably, the solvent includes, but is not limited to, one or more of acetonitrile, methanol, ethanol, isopropanol, trifluoroethanol, trifluoroacetic acid, hexafluoroisopropanol, trifluorotoluene, dimethylformamide, ethyl acetate, tetrahydrofuran, 1,4-dioxane, and dichloromethane.

[0026] Preferably, the volume ratio of aromatic hydrocarbon to solvent in the reaction is 0.5-20%.

[0027] Compared with the prior art, the advantages of the present invention are:

[0028] (1) Low-cost catalyst preparation process: The non-precious metal single-atom photocatalyst with tunable coordination configuration of the present invention can be prepared in large quantities through a simple process (physical mixing-thermal treatment method), which is simple to operate and conducive to large-scale industrial production;

[0029] (2) Highly efficient photocatalytic activity: This invention is the first to apply the coordination configuration regulation strategy of single-atom photocatalysts to the C(sp) of aromatic hydrocarbons. 3 Oxidation of the -H bond promotes O2 to O2 •- The activation process enhances the catalytic efficiency of heterogeneous photocatalysts in organic synthesis, achieving a toluene conversion rate as high as 79870 μmol g. -1 h -1 This is the highest value to date for heterogeneous toluene oxidation (< 5367 μmolg). -1 h -1 , ACS Catal. 2024, 14, 1, 249-261);

[0030] (3) Wide range of substrates: The method of the present invention is applicable to substrates containing various functional groups, and maintains good selectivity and reaction efficiency;

[0031] (4) Green heterogeneous photocatalysis technology: Compared with traditional thermochemistry, the photochemical technology of the present invention is cleaner and more energy-efficient; it uses green and inexpensive solvents and oxidizing gases, without the need for additional additives; in addition, the heterogeneous photocatalyst of the present invention can be recycled multiple times, and the catalyst still maintains good catalytic activity after five cycles of the reaction.

[0032] (5) Simple operation process: The present invention uses aromatic hydrocarbons as substrates and can efficiently synthesize aromatic aldehydes or ketones through a one-step photochemical reaction. The operation is simple and can be scaled up to 200 mmol substrate scale, and the reaction efficiency remains stable. Therefore, this method has great potential for industrial application. Attached Figure Description

[0033] Figure 1 This is a schematic diagram illustrating the regulation of coordination configuration in single-atom photocatalysts.

[0034] Figure 2 a is the synchrotron X-ray absorption fine structure spectrum of the Miller-based Fe-N3Cl coordinated single-atom photocatalyst; Figure 2 b is a transmission electron microscope (TEM) scan of the Fe-N3Cl single-atom photocatalyst.

[0035] Figure 3 a shows the O2 temperature-programmed desorption-mass spectra of three photocatalysts: Fe-N3Cl, Fe-N4, and melamine. Figure 3 b shows the electron paramagnetic resonance spectra of three photocatalysts: Fe-N3Cl, Fe-N4, and melamine. Detailed Implementation

[0036] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0037] This invention provides a method for synthesizing aromatic aldehydes and ketones using a single-atom photocatalyst. Using aromatic hydrocarbons of Formula I as raw materials, the method reacts under the conditions of a single-atom photocatalyst and visible light to obtain aromatic aldehydes or ketones of Formula II.

[0038] ;

[0039] In the formula, R 1 Including but not limited to one of H, 2-CH3, 3-CH3, 4-CH3, 2-Cl, 3-Cl, 4-Cl, 4-Br, 4-F, 4-MeO, 4-NO2, 4-CF3, 4-COOMe, 4-CN, and 4-CH2CN;

[0040] R 2 Including but not limited to one of H, CH3, CH2CH3, (CH2)2CH3, OCH2CH3, C6H5, (CH2)2C6H5, 4-F-C6H4, and pyridyl.

[0041] The single-atom photocatalyst is a melamine-based heterocoordinating single-atom photocatalyst; the preparation method of the melamine-based heterocoordinating single-atom photocatalyst includes the following steps: mixing a melamine precursor and a metal salt, pretreating and calcining to obtain a melamine-based heterocoordinating single-atom photocatalyst.

[0042] In some examples, the melamine precursor includes, but is not limited to, one of cyanamide, dicyandiamide, thiourea, urea, and melamine.

[0043] In some examples, the cation of the metal salt includes, but is not limited to, the non-noble metal ion NH4. + Zn 2+ Cu 2+ Ni 2+ Co 2+ Mg 2+ Mn 2+ Ca 2+ Fe 2+ Fe 3+ Cr 3+ Al 3+ W 3+ Ti 4+ V 5+ One of the following; the anion of the metal salt includes, but is not limited to, halide ions, CH3COO - NO3 - SO4 2- One of them.

[0044] In some examples, the mass of the melamine precursor is 1-100 times the mass of the metal salt.

[0045] In some examples, the pretreatment method includes, but is not limited to, ball milling, freeze drying, and sol-gel methods.

[0046] In some examples, the calcination temperature is 400-600 °C.

[0047] In some examples, the calcination atmosphere includes, but is not limited to, air, nitrogen, and argon.

[0048] The method for synthesizing aromatic aldehydes and ketones by single-atom photocatalysis includes the following steps: placing the aromatic hydrocarbon shown in Formula I and the single-atom photocatalyst in a reaction vessel, and reacting under visible light to obtain the aromatic aldehyde or ketone compound shown in Formula II.

[0049] In some examples, the reaction may or may not use a solvent.

[0050] In some examples, the wavelength of the visible light is 300-800 nm and the power is 3-120 W.

[0051] In some examples, the atmosphere of the reaction is oxygen or air.

[0052] In some examples, the reaction temperature is 20-120 °C; the reaction time is ≥3 h.

[0053] In some examples, the mass ratio of the single-atom photocatalyst to the aromatic hydrocarbon is 0.5-50%.

[0054] In some examples, the solvent includes, but is not limited to, one or more of acetonitrile, methanol, ethanol, isopropanol, trifluoroethanol, trifluoroacetic acid, hexafluoroisopropanol, trifluorotoluene, dimethylformamide, ethyl acetate, tetrahydrofuran, 1,4-dioxane, and dichloromethane.

[0055] In some examples, the volume ratio of aromatic hydrocarbons to solvent in the reaction is 0.5-20%.

[0056] Example 1

[0057] 4 g of ferric chloride and 10 g of melamine were ball-milled and mixed evenly, then calcined at 400-600 °C to obtain a single-atom photocatalyst. In a 10 mL Shrek tube, 1 mmol of toluene, 3 mL of hexafluoroisopropanol, and 10 mg of the single-atom photocatalyst were added. The mixture was reacted for 6 hours under an oxygen atmosphere at 25 °C and a 120 W, 390 nm LED lamp. The product composition was analyzed by gas chromatography using the internal standard method. The results are shown in Table 1. Table 1 shows that the optimal calcination temperature range for the preparation of the single-atom photocatalyst is 425-450 °C.

[0058] Table 1: Results of toluene oxidation using single-atom photocatalysts prepared at different calcination temperatures.

[0059]

[0060] Example 2

[0061] 0.5-10 g of ferric chloride and 10 g of melamine were ball-milled and mixed evenly, then calcined at 450 °C to obtain a single-atom photocatalyst. In a 10 mL Shrek tube, 1 mmol of toluene, 3 mL of hexafluoroisopropanol, and 10 mg of the single-atom photocatalyst were added. The reaction was carried out for 6 hours under an oxygen atmosphere and at 25 °C using a 120 W, 390 nm LED lamp. The product composition was analyzed by gas chromatography using the internal standard method, and the results are shown in Table 2. Table 2 shows that in the preparation of the single-atom photocatalyst, when the amount of melamine precursor added is 10 g, the optimal range for the amount of metal salt added is 4-7 g.

[0062] Table 2: Results of toluene oxidation using single-atom photocatalysts prepared with different metal salt masses

[0063]

[0064] Example 3

[0065] 4 g of ferric chloride and 10 g of melamine precursor were ball-milled and calcined at 450 °C to obtain a single-atom photocatalyst. In a 10 mL Shrek tube, 1 mmol of toluene, 3 mL of hexafluoroisopropanol, and 10 mg of the single-atom photocatalyst were added. The reaction was carried out for 6 hours under an oxygen atmosphere and at 25 °C using a 120 W, 390 nm LED lamp. The product composition was analyzed by gas chromatography using the internal standard method, and the results are shown in Table 3. Table 3 shows that, in the preparation of the single-atom photocatalyst, when ferric chloride is used as the metal salt, melamine is the optimal melamine precursor.

[0066] Table 3: Results of single-atom photocatalysts prepared from different melamine precursors for toluene oxidation

[0067]

[0068] The following focuses on analyzing the characteristics of the Miller-based heterocoordination single-atom photocatalyst and the method of the present invention, with reference to Examples 1-3.

[0069] Figure 1 The diagram illustrates the control of coordination configuration in single-atom photocatalysts. It shows that single-atom photocatalysts based on g-C3N4 have a coordination configuration that is not easily tunable (the coordination configuration of Fe-N4), while single-atom photocatalysts based on melamine have a highly tunable coordination configuration and can introduce external coordinating elements (such as chlorine to form the coordination configuration of Fe-N3Cl).

[0070] Figure 2 a is the fine structure spectrum of the catalyst obtained by synchrotron X-ray absorption. The spectrum fitting shows that the Fe metal center is coordinated by one Cl atom (2.40 Å) and three N atoms (2.12 Å), which can be used to deduce the coordination configuration of Fe-N3Cl. Figure 2 b is a transmission electron microscopy (TEM) scan of the Miller-based Fe-N3Cl single-atom photocatalyst, showing that Fe, N, and Cl are uniformly distributed in the catalyst.

[0071] Figure 3 a is the temperature-programmed desorption-mass spectrum of the photocatalyst for O2. The figure shows that the peak intensities of Fe-N3Cl and Fe-N4 are significantly higher than those of melamine, indicating that the introduction of Fe can significantly improve the catalyst's adsorption capacity for O2. Among them, Fe-N3Cl has the strongest peak and the highest O2 adsorption capacity. Figure 3 b is the electron paramagnetic resonance spectrum of the photocatalyst. The figure shows that the Fe-N3Cl configuration exhibits the strongest 5,5-dimethyl-1-pyrrolino-N-oxide (DMPO)-O2. •- The signal indicates that during the photocatalytic process, the Fe-N3Cl configuration of O2... •-The highest O2 generation rate and strongest O2 activation ability were observed. This indicates that in the Fe-N3Cl coordination configuration, the asymmetric N / Cl coordination can regulate the electronic structure of the Fe metal center, effectively promoting O2 adsorption and O2 activation. •- The generation of C(sp) aromatic hydrocarbons is significantly improved by photocatalysis. 3 The performance of )-H bond oxidation.

[0072] Example 4

[0073] 4 g of ferric chloride and 10 g of melamine were ball-milled and mixed evenly, then calcined at 450 °C to obtain a single-atom photocatalyst. In a 10 mL Shrek tube, 1 mmol of toluene, 3 mL of hexafluoroisopropanol, and 1-50 mg of the single-atom photocatalyst were added. The reaction was carried out for 6 hours under an oxygen atmosphere and at 25 °C using a 120 W, 390 nm LED lamp. The product composition was analyzed by gas chromatography using the internal standard method, and the results are shown in Table 4. Table 4 shows that to achieve optimal catalytic activity, when the amount of toluene substrate is 1 mmol, the optimal addition amount of the single-atom photocatalyst is 2-20 mg.

[0074] Table 4: Results of toluene oxidation using different amounts of single-atom photocatalyst

[0075]

[0076] Example 5

[0077] 4 g of ferric chloride and 10 g of melamine were ball-milled and mixed evenly, then calcined at 450 °C to obtain a single-atom photocatalyst. In a 10 mL Shrek tube, 1 mmol of toluene, 3 mL of solvent, and 10 mg of the single-atom photocatalyst were added. The reaction was carried out at 25 °C for 6 hours under an oxygen atmosphere and a 120 W LED lamp at 390 nm wavelength. The product composition was analyzed by gas chromatography using the internal standard method. The results are shown in Table 5. Table 5 shows that when toluene is the substrate, fluoroalcohol solvents are the most effective, with hexafluoroisopropanol being the optimal solvent.

[0078] Table 5: Results of Toluene Oxidation Using Different Solvents

[0079]

[0080] Example 6

[0081] 4 g of ferric chloride and 10 g of melamine were ball-milled and mixed evenly, then calcined at 450 °C to obtain a single-atom photocatalyst. In a 10 mL Shrek tube, 1 mmol of toluene, 1-10 mL of hexafluoroisopropanol, and 10 mg of the single-atom photocatalyst were added. The reaction was carried out for 6 hours under an oxygen atmosphere at 25 °C and a 120 W LED lamp at 390 nm wavelength. The product composition was analyzed by gas chromatography using the internal standard method, and the results are shown in Table 6. Table 6 shows that when the amount of toluene substrate is 1 mmol, the optimal solvent volume for maximizing the catalytic activity of the single-atom photocatalyst is 1-5 mL, with the optimum being 2 mL.

[0082] Table 6: Results of Toluene Oxidation with Different Solvent Volumes

[0083]

[0084] Example 7

[0085] 4 g of ferric chloride and 10 g of melamine were ball-milled and mixed evenly, then calcined at 450 °C to obtain a single-atom photocatalyst. In a 10 mL Shrek tube, 1 mmol of toluene, 3 mL of hexafluoroisopropanol, and 10 mg of the single-atom photocatalyst were added. The reaction was carried out for 6 hours under an oxygen atmosphere and at 25 °C with an LED lamp of 6-120 W and a wavelength of 370-450 nm. The product composition was analyzed by gas chromatography using the internal standard method, and the results are shown in Table 7. Table 7 shows that the optimal visible light wavelength is 390 nm and the optimal power is 120 W to maximize the catalytic activity of the single-atom photocatalyst.

[0086] Table 7: Results of toluene oxidation using different visible light wavelengths and powers

[0087]

[0088] Example 8

[0089] 4 g of ferric chloride and 10 g of melamine were ball-milled and mixed evenly, then calcined at 450 °C to obtain a single-atom photocatalyst. In a 10 mL Shrek tube, 1 mmol of aromatic hydrocarbon, 3 mL of hexafluoroisopropanol, and 10 mg of the single-atom photocatalyst were added. The reaction was carried out for 6 hours under an oxygen atmosphere and at 25 °C using a 120 W, 390 nm LED lamp. The product composition was analyzed by gas chromatography using the internal standard method, and the results are shown in Table 8. Table 8 shows that the single-atom photocatalyst of this invention has a broad substrate range. Halogen-substituted, alkyl-substituted, ester-substituted, cyano-substituted, and trifluoromethyl-substituted substrates all exhibited high conversion rates (55%-78%) and good selectivity (>90%). Furthermore, in the presence of multiple substituents, the selectivity for methyl aromatic hydrocarbons reached as high as 98%.

[0090] Table 8: Results of oxidation of different methyl aromatic substrates to aromatic aldehydes

[0091]

[0092] Example 9

[0093] 4 g of ferric chloride and 10 g of melamine were ball-milled and mixed evenly, then calcined at 450 °C to obtain a single-atom photocatalyst. In a 10 mL Shrek tube, 1 mmol of aromatic hydrocarbon, 3 mL of hexafluoroisopropanol, and 10 mg of the single-atom photocatalyst were added. The reaction was carried out for 6 hours under an oxygen atmosphere and at 25 °C using a 120 W, 390 nm LED lamp. The product composition was analyzed by internal standard method using gas chromatography, and the results are shown in Table 9. Table 9 shows that the single-atom photocatalyst of this invention has a broad substrate range. Commonly used homogeneous photocatalysts such as benzophenone and its derivatives, and anthraquinone and its derivatives, can be synthesized with high selectivity (95%-99%) and conversion (64%-98%). In addition to aromatic hydrocarbon oxidation, the oxidation of common cycloalkanes also exhibits excellent selectivity (85%-99%) and medium-to-high conversion (55%-91%). Furthermore, the oxidation selectivity of thiophene and thiazole is as high as 95% and 99%, respectively.

[0094] Table 9: Results of ketone oxidation reactions with different substrates

[0095]

[0096] Example 11

[0097] 4 g of ferric chloride and 10 g of melamine were ball-milled and mixed evenly, then calcined at 450 °C to obtain a single-atom photocatalyst. In a round-bottom flask, 200 mmol of toluene, 600 mL of hexafluoroisopropanol, and 2 g of the single-atom photocatalyst were added. The mixture was reacted for 100 hours under an oxygen atmosphere and at 25 °C using a 120 W LED lamp with a wavelength of 390 nm, yielding 14.01 g of benzaldehyde, with a yield of 66%. The scaled-up reaction results of this embodiment further demonstrate the great potential for industrial application of the single-atom photocatalytic system of this invention.

[0098] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A method for synthesizing aromatic aldehydes and ketones using a single-atom photocatalyst, characterized in that, Using aromatic hydrocarbons including those shown in Formula I as raw materials, under the conditions of a single-atom photocatalyst and visible light irradiation, aromatic aldehydes or ketones shown in Formula II are reacted to obtain them. ； In the formula, R 1 Including but not limited to one of H, 2-CH3, 3-CH3, 4-CH3, 2-Cl, 3-Cl, 4-Cl, 4-Br, 4-F, 4-MeO, 4-NO2, 4-CF3, 4-COOMe, 4-CN, and 4-CH2CN; R 2 Including but not limited to one of H, CH3, CH2CH3, (CH2)2CH3, OCH2CH3, C6H5, (CH2)2C6H5, 4-F-C6H4, and pyridyl.

2. The method for synthesizing aromatic aldehydes and ketones using a single-atom photocatalyst according to claim 1, characterized in that, The single-atom photocatalyst is a Milleramine-based heterocoordinated single-atom photocatalyst.

3. The method for synthesizing aromatic aldehydes and ketones using a single-atom photocatalyst according to claim 1, characterized in that, The mass ratio of the single-atom photocatalyst to the aromatic hydrocarbon is 0.5-50%.

4. The method for synthesizing aromatic aldehydes and ketones using a single-atom photocatalyst according to claim 1, characterized in that, The reaction temperature is 20-120 °C, and the reaction time is ≥3 h.

5. The method for synthesizing aromatic aldehydes and ketones using a single-atom photocatalyst according to claim 1, characterized in that, The visible light wavelength range of the reaction is 300-800 nm, and the power is 3-120 W.

6. The method for synthesizing aromatic aldehydes and ketones using a single-atom photocatalyst according to claim 2, characterized in that, The preparation method of the melamine-based heterocoordination single-atom photocatalyst includes the following steps: mixing a melamine precursor and a metal salt, pretreating and calcining the mixture to obtain the melamine-based heterocoordination single-atom photocatalyst.

7. The method for synthesizing aromatic aldehydes and ketones using a single-atom photocatalyst according to claim 6, characterized in that, The melamine precursor includes, but is not limited to, one of cyanamide, dicyandiamide, thiourea, urea, and melamine.

8. The method for synthesizing aromatic aldehydes and ketones using a single-atom photocatalyst according to claim 6, characterized in that, The cations of the metal salt include, but are not limited to, NH4. + Zn 2+ Cu 2+ Ni 2+ Co 2+ Mg 2+ Mn 2+ Ca 2+ Fe 2+ Fe 3+ Cr 3+ Al 3+ W 3+ Ti 4+ V 5+ One of the following; the anion of the metal salt includes, but is not limited to, halide ions, CH3COO - NO3 - SO4 2- One of them.

9. The method for synthesizing aromatic aldehydes and ketones using a single-atom photocatalyst according to claim 6, characterized in that, The mass of the melamine precursor is 1-100 times the mass of the metal salt.

10. The method for synthesizing aromatic aldehydes and ketones using a single-atom photocatalyst according to claim 6, characterized in that, The calcination temperature is 400-600 ℃.

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