A method for preparing benzaldehyde compounds by selectively oxidizing benzyl alcohol compounds using a heterogeneous copper catalyst
The selective oxidation of benzyl alcohol to benzaldehyde using a heterogeneous copper catalyst solves the problems of difficult recovery of homogeneous catalysts and high cost of precious metal catalysts, achieving highly selective and environmentally friendly industrial production.
Patent Information
- Application Number
- CN202410470038.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-18
- Publication Date
- 2026-08-04
- Estimated Expiration
- 2044-04-18
AI Technical Summary
In existing benzyl alcohol oxidation methods, homogeneous catalysts are difficult to recover, leading to pollution and waste. Furthermore, precious metal catalysts are expensive and difficult to implement on a large scale for industrial production.
A heterogeneous copper catalyst was developed using inexpensive and readily available polydopamine-supported copper as the catalyst and oxygen from the air as the oxidant. The heterogeneous copper catalyst was formed through a polymerization-supported reaction and used for the selective oxidation of benzyl alcohol.
It achieves highly selective synthesis of benzaldehyde, the catalyst can be recycled, reducing reaction costs, and is suitable for large-scale industrial production, making it environmentally friendly.
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Figure CN118164834B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of organic synthesis technology, and in particular to a method for preparing benzaldehyde compounds by selective oxidation of benzyl alcohol compounds using a heterogeneous copper catalyst. Background Technology
[0002] Benzaldehyde, an important chemical intermediate in the pharmaceutical and pesticide industries, has wide applications. Its preparation methods mainly include toluene oxidation and benzyl alcohol oxidation. Compared to toluene, benzyl alcohol is less toxic, cheaper, and has higher reaction efficiency; therefore, benzyl alcohol oxidation has become the most feasible method for preparing benzaldehyde. Traditional benzyl alcohol oxidation uses permanganate and dichromate as oxidants, which are highly toxic, generate large amounts of heavy metal waste, are environmentally unfriendly, and have poor selectivity. In recent years, chemists have developed numerous catalytic oxidation methods that use metals as catalysts and molecular oxygen as oxidants, avoiding the use of toxic and strong oxidants and providing a green pathway for the selective oxidation of benzyl alcohol.
[0003] Most reported catalytic oxidation methods are homogeneous reactions, where the catalysts cannot be recovered and reused, leading to pollution and waste. Compared to homogeneous catalysis, heterogeneous catalysis offers advantages such as catalyst stability and recyclability, better meeting the requirements of sustainable synthetic chemistry. However, existing heterogeneous catalytic technologies often require the use of precious metals such as Ru, Pt, Pd, Au, and Rh as catalysts, and the catalyst synthesis steps are complex, making large-scale industrial production difficult. Therefore, there is an urgent need for those skilled in the art to provide a simple, efficient, environmentally friendly, and low-cost method for the oxidation of benzyl alcohol. Summary of the Invention
[0004] The purpose of this invention is to provide a method for the selective oxidation of benzyl alcohol compounds to benzaldehyde compounds using a heterogeneous copper catalyst. This method can reduce reaction costs, is safe and environmentally friendly, and is particularly suitable for large-scale industrial production.
[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0006] This invention provides a method for the selective oxidation of benzyl alcohol compounds to benzaldehyde compounds using a heterogeneous copper catalyst.
[0007] The heterogeneous copper catalyst includes one or more of polydopamine-supported copper chloride, polydopamine-supported copper bromide, polydopamine-supported cuprous chloride, and polydopamine-supported cuprous bromide.
[0008] The oxidant used is oxygen from the air;
[0009] The benzyl alcohol compounds have the structure shown in Formula 1:
[0010]
[0011] The benzaldehyde compounds have the structure shown in Formula 2:
[0012]
[0013] In Formulas 1 and 2, R is hydrogen, alkyl, alkoxy, nitro or halogen.
[0014] Preferably, the method includes the following steps: mixing a heterogeneous copper catalyst, a benzyl alcohol-based compound, and an organic solvent, and then carrying out an oxidation reaction in air to obtain the benzaldehyde-based compound.
[0015] Preferably, the preparation method of the heterogeneous copper catalyst includes the following steps: mixing a buffer solution, dopamine hydrochloride, copper salt and iodobenzene acetate, carrying out a polymerization-supporting reaction to form polydopamine and supporting the copper salt to obtain the heterogeneous copper catalyst;
[0016] The pH value of the buffer solution is 8-9;
[0017] The copper salt includes one or more of copper chloride, copper bromide, cuprous chloride, and cuprous bromide.
[0018] Preferably, the molar ratio of dopamine hydrochloride to copper salt is 1:(1-5).
[0019] Preferably, the molar ratio of dopamine hydrochloride to iodobenzene acetate is 1:2.
[0020] Preferably, the buffer solution is a Tris-HCl buffer solution.
[0021] Preferably, the alkyl group includes p-methyl; the alkoxy group includes p-methoxy or o-methoxy; the halogen includes p-chlorine, p-bromine or m-chlorine; and the nitro group includes p-nitro or m-nitro.
[0022] Preferably, the ratio of the heterogeneous copper catalyst to benzyl alcohol is 10 mg: 0.1 mmol.
[0023] Preferably, the oxidation reaction is carried out at a temperature of 70–110°C.
[0024] Preferably, the organic solvent includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile, N-methylpyrrolidone, and 1,2-dichloroethane.
[0025] This invention provides a method for the selective oxidation of benzyl alcohol compounds to prepare benzaldehyde compounds using a heterogeneous copper catalyst. The heterogeneous copper catalyst includes one or more of polydopamine-supported copper chloride, polydopamine-supported copper bromide, polydopamine-supported cuprous chloride, and polydopamine-supported cuprous bromide. The oxidant used is oxygen from the air.
[0026] This invention utilizes readily available and inexpensive benzyl alcohol as a raw material. Under air conditions, without the addition of any additional oxidants or additives, and using non-toxic and environmentally friendly biomimetic material polydopamine-supported copper as a catalyst, it achieves the synthesis of benzaldehyde compounds through heterogeneous copper catalysis. This method is simple, easy to operate, and the catalyst is recyclable. It possesses advantages such as high reactivity, good selectivity, low reaction cost, and environmental friendliness. Attached Figure Description
[0027] Figure 1 GC-MS standard spectrum of benzaldehyde (top) and GC-MS test spectrum of compound 2a prepared in Example 1 (bottom);
[0028] Figure 2 The GC-MS standard spectrum of p-methylbenzaldehyde (top) and the GC-MS test spectrum of compound 2b prepared in Example 2 (bottom);
[0029] Figure 3 The GC-MS standard spectrum of p-chlorobenzaldehyde (top) and the GC-MS test spectrum of compound 2c prepared in Example 3 (bottom);
[0030] Figure 4 The GC-MS standard spectrum of p-bromobenzaldehyde (top) and the GC-MS test spectrum of compound 2d prepared in Example 4 (bottom);
[0031] Figure 5 GC-MS standard spectrum of m-chlorobenzaldehyde (top) and GC-MS test spectrum of compound 2e prepared in Example 5 (bottom);
[0032] Figure 6 GC-MS standard spectrum of o-methoxybenzaldehyde (top) and GC-MS test spectrum of compound 2f prepared in Example 6 (bottom);
[0033] Figure 7 The GC-MS standard spectrum of p-methoxybenzaldehyde (top) and the GC-MS test spectrum of 2g of the compound prepared in Example 7 (bottom);
[0034] Figure 8 The GC-MS standard spectrum of p-nitrobenzaldehyde (top) and the GC-MS test spectrum of the compound prepared in Example 8 at 2h (bottom);
[0035] Figure 9 GC-MS standard spectrum of m-nitrobenzaldehyde (top) and GC-MS test spectrum of compound 2i prepared in Example 9 (bottom). Detailed Implementation
[0036] This invention provides a method for the selective oxidation of benzyl alcohol compounds to benzaldehyde compounds using a heterogeneous copper catalyst.
[0037] The heterogeneous copper catalyst includes one or more of polydopamine-supported copper chloride, polydopamine-supported copper bromide, polydopamine-supported cuprous chloride, and polydopamine-supported cuprous bromide.
[0038] The oxidant used is oxygen from the air;
[0039] The benzyl alcohol compounds have the structure shown in Formula 1:
[0040]
[0041] The benzaldehyde compounds have the structure shown in Formula 2:
[0042]
[0043] In Formulas 1 and 2, R is hydrogen, alkyl, alkoxy, nitro or halogen.
[0044] Unless otherwise specified, all raw materials used in this invention are commercially available products well known in the art.
[0045] In this invention, the preparation method of the heterogeneous copper catalyst preferably includes the following steps: mixing a buffer solution, dopamine hydrochloride, copper salt and iodobenzene acetate, carrying out a polymerization-supporting reaction to form polydopamine and supporting the copper salt to obtain the heterogeneous copper catalyst.
[0046] In this invention, the buffer solution is preferably a Tris-HCl buffer solution; the pH value of the buffer solution is preferably 8 to 9, more preferably 8.5.
[0047] In this invention, the preparation of the Tris-HCl buffer preferably includes: dissolving tris(hydroxymethyl)aminomethane in a mixture of deionized water and anhydrous ethanol and stirring for 10 min; adjusting the pH value to the target value with 2M hydrochloric acid to obtain the Tris-HCl buffer. In this invention, the volume ratio of deionized water to anhydrous ethanol is preferably 1:3; the volume ratio of tris(hydroxymethyl)aminomethane to the deionized water-anhydrous ethanol mixture is preferably 5 mmol:100 mL.
[0048] In this invention, the preferred ratio of the buffer solution to dopamine hydrochloride is 100 mL: 1 mmol; the preferred molar ratio of dopamine hydrochloride to copper salt is 1:(1-5), specifically 1:1, 1:2, 1:3, 1:4, or 1:5; the preferred molar ratio of dopamine hydrochloride to iodobenzene acetate is 1:2. In this invention, the iodobenzene acetate serves to oxidize dopamine polymerization.
[0049] In this invention, the copper salt includes one or more of copper chloride, copper bromide, cuprous chloride, and cuprous bromide, preferably copper chloride. In this invention, the heterogeneous catalyst (i.e., polydopamine-supported copper chloride) exhibits the best catalytic performance when the copper salt is copper chloride.
[0050] In this invention, the polymerization-supported reaction is preferably carried out under stirring conditions, the preferred temperature is 30°C, and the preferred time is 1 hour. During the polymerization-supported reaction, dopamine hydrochloride forms polydopamine (PDA), and simultaneously, copper salt is loaded onto the polydopamine to obtain the catalyst CuL. n @PDA, the specific reaction equation is as follows:
[0051]
[0052] After the polymerization-supporting reaction is completed, the resulting reaction system is centrifuged to obtain solid particles. These solid particles are then washed multiple times with deionized water and dried to obtain a heterogeneous copper catalyst. In this invention, the washing is preferably performed three times; the drying temperature is preferably 60°C. This invention does not have specific requirements for the drying time, as long as surface dryness is achieved.
[0053] In this invention, polydopamine has the advantages of being inexpensive, readily available, non-toxic, safe, environmentally friendly, stable, and easy to recycle. The catechol / ortho-quinone groups contained in its structure have the ability to chelate metals. This invention utilizes polydopamine loaded with copper salts to form a heterogeneous catalyst for the selective oxidation reaction of benzyl alcohol compounds, which can reduce reaction costs, is safe and green, and is particularly suitable for large-scale industrial production.
[0054] The method for selectively oxidizing benzyl alcohol compounds to benzaldehyde compounds using a heterogeneous copper catalyst provided by the present invention preferably includes the following steps:
[0055] A heterogeneous copper catalyst, benzyl alcohol-based compounds, and an organic solvent are mixed and oxidized in air to obtain the benzaldehyde-based compounds.
[0056] In this invention, the benzyl alcohol compounds have the structure shown in Formula 1:
[0057]
[0058] In Formula 1, R is hydrogen, alkyl, alkoxy, nitro, or halogen; the alkyl group preferably includes p-methyl; the alkoxy group preferably includes p-methoxy or o-methoxy; the halogen preferably includes p-chlorine, p-bromine, or m-chlorine; and the nitro group preferably includes p-nitro or m-nitro.
[0059] In this invention, the preferred ratio of the heterogeneous copper catalyst to benzyl alcohol is 10 mg: 0.1 mmol.
[0060] In this invention, the organic solvent preferably includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile, N-methylpyrrolidone and 1,2-dichloroethane; the ratio of the benzyl alcohol compound to the polar solvent is preferably 0.5 mmol: 1.0 mL.
[0061] In this invention, the temperature of the oxidation reaction is preferably 70-110°C, more preferably 110°C; the time of the oxidation reaction is not particularly important in this invention, but is preferably monitored by TLC.
[0062] In this invention, the oxidation reaction is preferably carried out under stirring conditions.
[0063] In this invention, taking benzyl alcohol as an example, the equation for the oxidation reaction is as follows:
[0064]
[0065] After the oxidation reaction is completed, the present invention preferably centrifuges the oxidation reaction system to separate the catalyst, obtaining a reaction solution (containing benzaldehyde compounds, organic solvents, and unreacted benzyl alcohol compounds). The organic solvents and benzyl alcohol compounds in the reaction solution are then removed to obtain benzaldehyde compounds. The present invention does not have special requirements for the removal method of the organic solvents and benzyl alcohol compounds; any removal method well known in the art is acceptable.
[0066] This invention utilizes the biomimetic material polydopamine as a metal carrier to achieve catalyst recycling, solving the problems of poor selectivity, environmental pollution, complex catalyst preparation process, high cost, and low practicality in existing benzyl alcohol oxidation reactions.
[0067] The following detailed description, in conjunction with embodiments, illustrates the method for the selective oxidation of benzyl alcohol compounds to benzaldehyde compounds using a heterogeneous copper catalyst, as provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.
[0068] The preparation process of the heterogeneous catalyst used in the following examples is as follows:
[0069] Tris(hydroxymethyl)aminomethane (5 mmol) was dissolved in deionized water (25 mL) and anhydrous ethanol (75 mL) and stirred for 10 minutes. The pH was adjusted with 2 M hydrochloric acid to obtain a buffer solution with pH = 8.5, denoted as Tris-HCl buffer. Subsequently, dopamine hydrochloride (1 mmol), CuCl2 (1 mmol), and iodobenzene acetate (2 mmol) were added sequentially to the Tris-HCl buffer. The mixture was stirred at 30 °C for 1 hour, centrifuged to obtain solid particles, washed three times with deionized water, and dried at 60 °C to obtain a heterogeneous catalyst, denoted as CuCl2@PDA.
[0070] The heterogeneous catalysts obtained by replacing CuCl2 with CuBr2, CuCl and CuBr respectively are denoted as CuBr2@PDA, CuCl@PDA and CuBr@PDA respectively.
[0071] Example 1
[0072]
[0073] Benzyl alcohol 1a (0.5 mmol, 52 μL), catalyst CuCl2@PDA (50 mg), and solvent 1,2-dichloroethane (1.0 mL) were added sequentially to the reactor, and the mixture was heated and stirred at 110 °C for 12 h. After the reaction was completed, the reaction solution was obtained by centrifugation. The yield of the reaction solution was determined by gas chromatography-mass spectrometry (GC-MS), using ethyl benzoate as an internal standard. The yield of benzaldehyde 2a was 88% (because benzyl alcohol was only oxidized to benzaldehyde and not converted into other substances, the remaining unconverted portion was benzyl alcohol, which did not react further with extended time. Therefore, the yield here can also be understood as the reaction conversion rate, and the same understanding will be applied to yields in subsequent reactions). The GC-MS standard spectrum of benzaldehyde (top) and the GC-MS test spectrum of compound 2a prepared in Example 1 (bottom) are shown below. Figure 1 .
[0074] Example 2
[0075]
[0076] p-Toluenebenzyl alcohol 1b (0.5 mmol, 62 μL), catalyst CuCl2@PDA (50 mg), and solvent 1,2-dichloroethane (1.0 mL) were added sequentially to the reactor, and the mixture was heated and stirred at 110 °C for 12 h. After the reaction was completed, the reaction solution was obtained by centrifugation. The yield of the reaction solution was determined by GC-MS, and with ethyl benzoate as an internal standard, the yield of p-toluenebenzaldehyde 2b was 93%. The GC-MS standard spectrum of p-toluenebenzaldehyde (top) and the GC-MS test spectrum of compound 2b prepared in Example 2 (bottom) are shown below. Figure 2 .
[0077] Example 3
[0078]
[0079] p-Chlorobenzyl alcohol 1c (0.5 mmol, 71.3 mg), catalyst CuCl2@PDA (50 mg), and solvent 1,2-dichloroethane (1.0 mL) were added sequentially to the reactor, and the mixture was heated and stirred at 110 °C for 12 h. After the reaction was completed, the reaction solution was obtained by centrifugation. The yield of the reaction solution was determined by GC-MS, and with ethyl benzoate as an internal standard, the yield of p-chlorobenzaldehyde 2c was 92%. The GC-MS standard spectrum of p-chlorobenzaldehyde (top) and the GC-MS test spectrum of compound 2c prepared in Example 3 (bottom) are shown below. Figure 3 .
[0080] Example 4
[0081]
[0082] p-Bromobenzaldehyde 1d (0.5 mmol, 93.5 mg), catalyst CuCl2@PDA (50 mg), and solvent 1,2-dichloroethane (1.0 mL) were added sequentially to the reactor, and the mixture was heated and stirred at 110 °C for 12 h. After the reaction was completed, the reaction solution was obtained by centrifugation. The yield of the reaction solution was determined by GC-MS, and with ethyl benzoate as an internal standard, the yield of p-bromobenzaldehyde 2d was 90%. The GC-MS standard spectrum of p-bromobenzaldehyde (top) and the GC-MS test spectrum of compound 2d prepared in Example 4 (bottom) are shown below. Figure 4 .
[0083] Example 5
[0084]
[0085] The reactor was sequentially filled with m-chlorobenzyl alcohol 1e (0.5 mmol, 59 μL), catalyst CuCl2@PDA (50 mg), and solvent 1,2-dichloroethane (1.0 mL), and heated and stirred at 110 °C for 12 h. After the reaction was completed, the reaction solution was obtained by centrifugation. The yield of the reaction solution was determined by GC-MS, and with ethyl benzoate as an internal standard, the yield of m-chlorobenzaldehyde 2e was 89%. The GC-MS standard spectrum of m-chlorobenzaldehyde (top) and the GC-MS test spectrum of compound 2e prepared in Example 5 (bottom) are shown below. Figure 5 .
[0086] Example 6
[0087]
[0088] o-Methoxybenzyl alcohol 1f (0.5 mmol, 66 μL), catalyst CuCl2@PDA (50 mg), and solvent 1,2-dichloroethane (1.0 mL) were added sequentially to the reactor, and the mixture was heated and stirred at 110 °C for 12 h. After the reaction was completed, the reaction solution was obtained by centrifugation. The yield of the reaction solution was determined by GC-MS, and ethyl benzoate was used as an internal standard. The yield of o-methoxybenzaldehyde 2f was 90%. The GC-MS standard spectrum of o-methoxybenzaldehyde (top) and the GC-MS test spectrum of compound 2f prepared in Example 6 (bottom) are shown below. Figure 6 .
[0089] Example 7
[0090]
[0091] 1 g (0.5 mmol, 62 μL) of p-methoxybenzyl alcohol, 50 mg of CuCl2@PDA catalyst, and 1.0 mL of 1,2-dichloroethane solvent were added sequentially to the reactor, and the mixture was heated and stirred at 110 °C for 12 h. After the reaction was completed, the reaction solution was obtained by centrifugation. The yield of the reaction solution was determined by GC-MS, and ethyl benzoate was used as an internal standard. The yield of 2 g of p-methoxybenzaldehyde was 90%. The GC-MS standard spectrum of p-methoxybenzaldehyde (top) and the GC-MS test spectrum of 2 g of the compound prepared in Example 7 (bottom) are shown below. Figure 7 .
[0092] Example 8
[0093]
[0094] p-Nitrobenzyl alcohol (0.5 mmol, 76.5 mg), catalyst CuCl2@PDA (50 mg), and solvent 1,2-dichloroethane (1.0 mL) were added sequentially to the reactor, and the mixture was heated and stirred at 110 °C for 20 h. After the reaction was completed, the reaction solution was obtained by centrifugation. The yield of the reaction solution was determined by GC-MS, and with ethyl benzoate as an internal standard, the yield of p-nitrobenzaldehyde 2 h was 65%. The GC-MS standard spectrum of p-nitrobenzaldehyde (top) and the GC-MS test spectrum of the compound prepared in Example 8 2 h (bottom) are shown below. Figure 8 .
[0095] Example 9
[0096]
[0097] The reactor was sequentially filled with m-nitrobenzyl alcohol 1i (0.5 mmol, 59 μL), catalyst CuCl2@PDA (50 mg), and solvent 1,2-dichloroethane (1.0 mL), and heated and stirred at 110 °C for 16 h. After the reaction was completed, the reaction solution was obtained by centrifugation. The yield of the reaction solution was determined by GC-MS, and with ethyl benzoate as an internal standard, the yield of m-nitrobenzaldehyde 2i was 51%. The GC-MS standard spectrum of m-nitrobenzaldehyde (top) and the GC-MS test spectrum of compound 2i prepared in Example 9 (bottom) are shown below. Figure 9 .
[0098] Example 10
[0099] The only difference from Example 1 is that CuCl@PDA was used as a catalyst, resulting in a benzaldehyde 2a yield of 69%.
[0100] Example 11
[0101] The only difference from Example 1 is that CuBr2@PDA was used as a catalyst, resulting in a benzaldehyde 2a yield of 71%.
[0102] Example 12
[0103] The only difference from Example 1 is that CuBr@PDA was used as a catalyst, resulting in a benzaldehyde 2a yield of 66%.
[0104] Cyclic stability test:
[0105] The catalyst separated in Example 1 was reused 6 times, and the yield of benzaldehyde obtained each time is shown in Table 1.
[0106] Table 1. Stability test results of the catalyst
[0107] 1st time 88％ 2nd time 84％ 3rd 80％ 4th 72％ 5th 64％ 6th 52％
[0108] As shown in Table 1, the present invention utilizes a heterogeneous copper catalyst to selectively oxidize benzyl alcohol compounds to prepare benzaldehyde compounds. The heterogeneous copper catalyst can be recycled, and the target product still has a high yield after 6 uses.
[0109] 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 the selective oxidation of benzyl alcohol compounds to benzaldehyde compounds using a heterogeneous copper catalyst, characterized in that, The heterogeneous copper catalyst includes one or more of polydopamine-supported copper chloride, polydopamine-supported copper bromide, polydopamine-supported cuprous chloride, and polydopamine-supported cuprous bromide. The oxidant used is oxygen from the air; The benzyl alcohol compounds have the structure shown in Formula 1: Formula 1; The benzaldehyde compounds have the structure shown in Formula 2: Formula 2; In Formulas 1 and 2, R is hydrogen, alkyl, alkoxy, nitro or halogen; The preparation method of the heterogeneous copper catalyst includes the following steps: mixing a buffer solution, dopamine hydrochloride, copper salt and iodobenzene acetate, carrying out a polymerization-supporting reaction to form polydopamine and supporting the copper salt to obtain the heterogeneous copper catalyst; The pH value of the buffer solution is 8-9; The copper salt includes one or more of copper chloride, copper bromide, cuprous chloride, and cuprous bromide.
2. The method according to claim 1, characterized in that, The process includes the following steps: mixing a heterogeneous copper catalyst, a benzyl alcohol-based compound, and an organic solvent, and then performing an oxidation reaction in air to obtain the benzaldehyde-based compound.
3. The method according to claim 1, characterized in that, The molar ratio of dopamine hydrochloride to copper salt is 1:(1~5).
4. The method according to claim 1, characterized in that, The molar ratio of dopamine hydrochloride to iodobenzene acetate is 1:
2.
5. The method according to claim 1, characterized in that, The buffer solution is Tris-HCl buffer solution.
6. The method according to claim 1 or 2, characterized in that, The alkyl group includes p-methyl; the alkoxy group includes p-methoxy or o-methoxy; the halogen includes p-chlorine, p-bromine or m-chlorine; and the nitro group includes p-nitro or m-nitro.
7. The method according to claim 1 or 2, characterized in that, The ratio of the heterogeneous copper catalyst to benzyl alcohol compounds is 10 mg: 0.1 mmol.
8. The method according to claim 2, characterized in that, The oxidation reaction is carried out at a temperature of 70~110℃.
9. The method according to claim 2, characterized in that, The organic solvent includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile, N-methylpyrrolidone, and 1,2-dichloroethane.