A catalyst for synthesizing 2,4,6-triarylpyridine compounds and a method for preparing 2,4,6-triarylpyridine compounds
Patent Information
- Application Number
- CN202610867308.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-16
- Publication Date
- 2026-11-03
AI Technical Summary
Existing methods for synthesizing 2,4,6-triarylpyridine compounds suffer from drawbacks such as cumbersome catalyst preparation, long reaction time, low product yield, high energy consumption, and the use of toxic solvents. Furthermore, there is a lack of research and application of metal-organic framework materials/metal Schiff base complexes as catalysts.
2,4,6-triarylpyridine compounds were synthesized in ethanol solvent via a one-step condensation reaction using a MIL-100(Fe)/bis(salicylaldehyde) ethylenediamine copper composite material as a catalyst. The catalysis was carried out using a nanocomposite catalyst of metal-organic framework material and metal Schiff base.
The efficient and green synthesis of 2,4,6-triarylpyridine compounds was achieved. The catalyst has high activity and good stability, is easy to separate and reuse, has high product yield, few by-products, mild reaction conditions, and good environmental compatibility.
Smart Images
Figure CN123024577A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of fine chemical technology, specifically relating to a catalyst for synthesizing 2,4,6-triarylpyridine compounds and a method for preparing 2,4,6-triarylpyridine compounds. Background Technology
[0002] 2,4,6-Triarylpyridines are an important class of organic compounds widely used in fine synthesis, pesticides, pharmaceuticals, and fluorescent materials. Traditional methods for synthesizing 2,4,6-triarylpyridine derivatives mainly employ the Hantzsch reaction, involving the condensation of 1,5-diketones and formamide formic acid. However, this method suffers from problems such as numerous byproducts and low product yields. Later, various synthetic methods were proposed. For example, using benzylamine or amino acids as nitrogen sources, 2,4,6-triarylpyridines can be synthesized by catalysis with chalcone or acetophenone in the presence of catalysts such as Cu(OTf)₂; using oxime acetate as a nitrogen source, 2,4,6-triarylpyridines can be synthesized by catalysis with acetophenone and aldehydes in the presence of catalysts such as bromide ketones; and using ammonium acetate as a nitrogen source, aromatic aldehydes or benzyl halides, or aromatic ketones can be synthesized by catalysis with catalysts such as heteropoly acids. However, the synthetic methods reported above all suffer from drawbacks to varying degrees, such as cumbersome catalyst preparation, long reaction times, low product yields, high energy consumption, or the use of toxic solvents. Therefore, developing environmentally friendly and efficient new methods for the synthesis of 2,4,6-triarylpyridine compounds is of great significance in addressing the shortcomings of existing technologies.
[0003] Metal-organic frameworks (MOFs) possess unique advantages and broad application prospects in catalysis due to their large specific surface area, tunable pore structure, structural diversity, and ease of functionalization. Metal Schiff base complexes are an important class of catalysts, exhibiting high activity and selectivity in reactions such as hydroxylation, condensation, and epoxidation. Currently, there are no studies or reports on the use of MOFs / metal Schiff base complexes as catalysts for the preparation of 2,4,6-triarylpyridine compounds. Therefore, developing green, efficient, and highly selective nanocomposite catalysts based on MOF composites and metal Schiff bases for the catalytic reaction preparation of 2,4,6-triarylpyridine compounds is of great significance. Summary of the Invention
[0004] This invention addresses the problems existing in the prior art by providing a catalyst for synthesizing 2,4,6-triarylpyridine compounds, and a method for preparing 2,4,6-triarylpyridine compounds using the catalyst.
[0005] The present invention adopts the following technical solution:
[0006] (I) This invention provides a catalyst for the synthesis of 2,4,6-triarylpyridine compounds, wherein the catalyst is a MIL-100(Fe) / bis(salicylaldehyde)ethylenediamine copper composite material, and the preparation method includes the following steps: Salicylaldehyde, ethylenediamine and solvent were mixed and heated to react, yielding H2salen ligand; Ferric nitrate, pyromellitic acid and solvent were mixed and heated to react, yielding MIL-100 (Fe). Copper acetate, MIL-100(Fe) and solvent are mixed. After the reaction is complete, MIL-100(Fe) impregnated with copper ions is obtained. The catalyst was obtained by mixing H2salen ligand, MIL-100 (Fe) impregnated with copper ions, and solvent, and then heating the mixture.
[0007] Furthermore, the molar ratio of salicylaldehyde to ethylenediamine is (1.5~2.5):1, preferably 2:1; the reaction temperature of salicylaldehyde and ethylenediamine is 70~80 ℃, and the reaction time is 1~3 h, preferably 2 h.
[0008] Furthermore, the molar ratio of ferric nitrate to trimellitic acid is (1.5~2.5):1, preferably 2:1; the reaction temperature of ferric nitrate and trimellitic acid is 150~160 ℃, and the reaction time is 10~15 h, preferably 12 h.
[0009] Furthermore, the mass ratio of copper acetate to MIL-100 (Fe) is (4~12):100, preferably 1:10; the reaction temperature of copper acetate and MIL-100 (Fe) is 20~30 ℃, and the reaction time is 10~15 h, preferably 12 h.
[0010] Furthermore, the mass ratio of the H2salen ligand to the MIL-100 (Fe) impregnated with copper ions is (1~2):1, preferably (1~1.5):1; the reaction temperature of the H2salen ligand and the impregnated copper ions is 70~80 ℃, and the reaction time is 20~25 h, preferably 24 h.
[0011] Furthermore, the solvent used in the preparation of H2salen ligand is excess ethanol; the solvent used in the preparation of MIL-100(Fe) is excess deionized water; the solvent used in the preparation of copper-impregnated MIL-100(Fe) is excess ethanol; and the solvent used in the preparation of the catalyst from H2salen ligand and copper-impregnated MIL-100(Fe) is excess acetone.
[0012] (II) This invention also provides a method for preparing 2,4,6-triarylpyridine compounds, wherein the method comprises: using aromatic aldehydes, aromatic ketones, and a nitrogen source as raw materials, and ethanol as a solvent, a one-step condensation reaction is carried out in the presence of a catalyst to generate 2,4,6-triarylpyridine compounds; the catalyst is the catalyst described in (I) of this invention. The reaction mechanism is as follows:
[0013] Further, the molar ratio of the aromatic aldehyde compound, the aromatic ketone compound and the nitrogen source is 1:2:(1~1.5), more preferably 1:2:(1~1.2); the mass of the catalyst is 0.1~2% of the total mass of the raw materials, more preferably 0.1~1%.
[0014] Furthermore, the reaction temperature is 40~80 ℃, more preferably 50~70 ℃, and the reaction time is 1~10 h, preferably 1~5 h, more preferably 1~3 h.
[0015] Furthermore, the aromatic aldehyde compound is benzaldehyde, p-methylbenzaldehyde, o-methoxybenzaldehyde, p-nitrobenzaldehyde, or p-chlorobenzaldehyde; the aromatic ketone compound is acetophenone; and the nitrogen source is ammonium acetate.
[0016] Furthermore, after the reaction to prepare 2,4,6-triarylpyridine compounds is completed, the reactants are cooled and allowed to stand, the lower catalyst layer is recovered by centrifugation, dried and recovered, and reused for the next batch of catalytic reactions. The upper product is recovered by solvent recovery, the crude product is recrystallized from ethanol, and dried to obtain the target product.
[0017] The beneficial effects of this invention are: (1) The metal-organic framework material / metal Schiff base nanocomposite Cusalen / MIL-100(Fe) prepared by the present invention has high catalyst activity and good stability. In addition, the catalyst is easy to separate and recover from the reaction system. After multiple cycles, its catalytic performance remains basically unchanged and can still play a stable catalytic role, with good reusability. (2) This invention uses aromatic aldehydes, aromatic ketones and nitrogen sources as raw materials, ethanol as solvent, and condensation reaction in one step under the action of a catalyst to generate 2,4,6-triarylpyridine compounds. The reaction process is simple to operate, does not use toxic and harmful reagents, is green and efficient, and has a high product yield. (3) The raw materials used in this invention are widely available, easy to obtain, and low in cost. There are few side reactions during the reaction process, and the types and contents of by-products generated are few, which simplifies the subsequent separation and purification steps. Overall, the preparation method has mild reaction conditions, good environmental compatibility, and strong practicality. Attached Figure Description
[0018] Figure 1 These are SEM images of the catalyst 10% Cusalen / MIL-100 (Fe) prepared in Example 1 before the reaction (a) and after 5 recycling cycles (b); Figure 2 The images show the EDX graphs of the catalyst 10% Cusalen / MIL-100 (Fe) prepared in Example 1 before the reaction (a) and after 5 recycling cycles (b). Figure 3 The product obtained in Example 9 1 H NMR spectrum; Figure 4 The product obtained in Example 13 1 H NMR spectrum; Figure 5 The product obtained in Example 14 1 H NMR spectrum; Figure 6 The product obtained in Example 15 1 H NMR spectrum; Figure 7 The product obtained in Example 16 1 H NMR spectrum. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, 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.
[0020] Example 1 This invention provides a catalyst for synthesizing 2,4,6-triarylpyridine compounds, and the preparation method includes the following steps: Step S1: Mix salicylaldehyde (0.2 mol), ethylenediamine (0.1 mol), and ethanol (80 mL), and react at 80 °C for 2 h. After the reaction is complete, cool and filter, recrystallize the solid with ethanol, and finally dry to obtain H2salen ligand.
[0021] Step S2: Mix ferric nitrate (0.02 mol), trimesic acid (0.01 mol), and deionized water (50 mL) in a hydrothermal reactor lined with polytetrafluoroethylene at 160 °C for 12 hours. After the reaction is complete, cool the mixture, filter to obtain the solid, wash the solid with water and ethanol in sequence, and finally dry it under vacuum at 120 °C for 12 hours to obtain MIL-100 (Fe).
[0022] Step S3: Mix MIL-100 (Fe) (1 g), copper acetate (0.04 g, 0.06 g, 0.08 g, 0.1 g or 0.12 g) with ethanol (15 mL), stir and react at 30 °C for 12 hours. After the reaction is complete, recover the solvent and dry to obtain MIL-100 (Fe) impregnated with copper ions.
[0023] Following the method in step S3, MIL-100(Fe) and copper acetate were mixed and reacted in the above 5 proportions to obtain 5 groups of MIL-100(Fe) impregnated with different amounts of copper ions.
[0024] Step S4: Mix H2salen ligand (1.3 g), MIL-100 (Fe) (1 g) impregnated with copper ions prepared in step S3, and acetone (30 mL). React at 80 °C for 24 h. After the reaction is complete, cool and filter the mixture, collect the crude solid product, and then place the solid in a Soxhlet extractor for reflux extraction with acetone as solvent to remove any soluble impurities that may be present. After extraction, collect the solid and dry it to obtain the catalyst.
[0025] Following the method in step S4, H2salen ligands were mixed and reacted with five groups of MIL-100(Fe) impregnated with different amounts of copper ions to obtain five groups of metal-organic framework / metal Schiff base nanocomposites Cusalen / MIL-100(Fe). These were designated as 4% Cusalen / MIL-100(Fe), 6% Cusalen / MIL-100(Fe), 8% Cusalen / MIL-100(Fe), 10% Cusalen / MIL-100(Fe), and 12% Cusalen / MIL-100(Fe), respectively.
[0026] The thermal stability of the five catalysts prepared was analyzed. The results showed that the Cusalen / MIL-100(Fe) metal-organic framework / metal Schiff base nanocomposite material had good thermal stability and could be used stably below 220 °C.
[0027] Example 2 This invention provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, benzaldehyde (0.1 mol), acetophenone (0.2 mol), ammonium acetate (0.12 mol), 4% Cusalen / MIL-100 (Fe) (0.3 g) prepared in Example 1, and ethanol (30 mL) were added. The mixture was then stirred at 80 °C for 5 hours. After the reaction was completed, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the lower catalyst layer was recovered. After drying, the catalyst layer could be recycled for reuse in the next batch of catalytic reactions. The upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a purified solid product with a yield of 61%. The purity was 89.4% as determined by 1H NMR analysis.
[0028] Example 3 This invention provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, benzaldehyde (0.1 mol), acetophenone (0.2 mol), ammonium acetate (0.12 mol), 6% Cusalen / MIL-100 (Fe) (0.3 g) prepared in Example 1, and ethanol (30 mL) were added, and the mixture was stirred at 80 °C for 5 hours. After the reaction was completed, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the lower catalyst layer was recovered. After drying, the catalyst could be reused for the next batch of catalytic reactions. The upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a purified solid product with a yield of 73%. 1 ¹H NMR analysis showed a purity of 91.2%.
[0029] Example 4 This invention provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, benzaldehyde (0.1 mol), acetophenone (0.2 mol), ammonium acetate (0.11 mol), 8% Cusalen / MIL-100 (Fe) (0.3 g) prepared in Example 1, and ethanol (30 mL) were added, and the mixture was stirred at 70 °C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the lower catalyst layer was recovered. After drying, the catalyst could be recycled for reuse in the next batch of catalytic reactions. The upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a purified solid product with a yield of 87%. 1 ¹H NMR analysis showed a purity of 94.8%.
[0030] Example 5 This invention provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, benzaldehyde (0.1 mol), acetophenone (0.2 mol), ammonium acetate (0.11 mol), 10% Cusalen / MIL-100 (Fe) (0.3 g) prepared in Example 1, and ethanol (30 mL) were added, and the mixture was stirred at 70 °C for 3 hours. After the reaction was completed, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the lower catalyst layer was recovered. After drying, the catalyst could be recycled for reuse in the next batch of catalytic reactions. The upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a purified solid product with a yield of 93%. 1 ¹H NMR analysis showed a purity of 98.2%.
[0031] Example 6 This invention provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, benzaldehyde (0.1 mol), acetophenone (0.2 mol), ammonium acetate (0.11 mol), 12% Cusalen / MIL-100 (Fe) (0.3 g) prepared in Example 1, and ethanol (30 mL) were added, and the mixture was stirred at 70 °C for 3 hours. After the reaction was completed, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the lower catalyst layer was recovered. After drying, the catalyst could be recycled for reuse in the next batch of catalytic reactions. The upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a purified solid product with a yield of 90%. 1 ¹H NMR analysis showed a purity of 97.6%.
[0032] Example 7 This invention provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, benzaldehyde (0.1 mol), acetophenone (0.2 mol), ammonium acetate (0.11 mol), 10% Cusalen / MIL-100 (Fe) (0.1 g) prepared in Example 1, and ethanol (30 mL) were added. The mixture was then stirred at 80 °C for 10 hours. After the reaction, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the lower catalyst layer was recovered. After drying, the catalyst could be reused for the next batch of catalytic reactions. The upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a purified solid product with a yield of 63%. 1 ¹H NMR analysis showed a purity of 96.6%.
[0033] Example 8 This invention provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, benzaldehyde (0.1 mol), acetophenone (0.2 mol), ammonium acetate (0.11 mol), 10% Cusalen / MIL-100 (Fe) (0.2 g) prepared in Example 1, and ethanol (30 mL) were added, and the mixture was stirred at 80 °C for 5 hours. After the reaction was completed, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the lower catalyst layer was recovered. After drying, the catalyst could be recycled for reuse in the next batch of catalytic reactions. The upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a purified solid product with a yield of 85%. 1 ¹H NMR analysis showed a purity of 97.7%.
[0034] Example 9 This invention provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, benzaldehyde (0.1 mol), acetophenone (0.2 mol), ammonium acetate (0.11 mol), 10% Cusalen / MIL-100 (Fe) (0.45 g) prepared in Example 1, and ethanol (30 mL) were added. The mixture was then stirred at 70 °C for 2 hours. After the reaction was complete, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the lower catalyst layer was recovered. After drying, the catalyst could be reused for the next batch of catalytic reactions. The upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a purified solid product with a yield of 96%. 1 H NMR analysis is shown in Figure 3 The purity is 98.8%.
[0035] Example 10 This invention provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, benzaldehyde (0.1 mol), acetophenone (0.2 mol), ammonium acetate (0.11 mol), 10% Cusalen / MIL-100 (Fe) (0.4 g) prepared in Example 1, and ethanol (30 mL) were added, and the mixture was stirred at 70 °C for 2 hours. After the reaction was completed, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the lower catalyst layer was recovered. After drying, the catalyst could be recycled for reuse in the next batch of catalytic reactions. The upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a purified solid product with a yield of 95%. 1 ¹H NMR analysis showed a purity of 98.5%.
[0036] Example 11 This invention provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, benzaldehyde (0.2 mol), acetophenone (0.4 mol), ammonium acetate (0.22 mol), 10% Cusalen / MIL-100 (Fe) (0.7 g) prepared in Example 1, and ethanol (80 mL) were added, and the mixture was stirred at 70 °C for 2 hours. After the reaction was completed, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the lower catalyst layer was recovered. After drying, the catalyst could be recycled for reuse in the next batch of catalytic reactions. The upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a purified solid product with a yield of 96%. 1 ¹H NMR analysis showed a purity of 98.6%.
[0037] Example 12 This invention provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, benzaldehyde (0.4 mol), acetophenone (0.6 mol), ammonium acetate (0.33 mol), 10% Cusalen / MIL-100 (Fe) (0.4 g) prepared in Example 1, and ethanol (100 mL) were added, and the mixture was stirred at 70 °C for 2 hours. After the reaction was completed, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the lower catalyst layer was recovered. After drying, the catalyst could be recycled for reuse in the next batch of catalytic reactions. The upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a purified solid product with a yield of 95%. 1 ¹H NMR analysis showed a purity of 98.4%.
[0038] Example 13 This invention provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, 0.1 mol of p-methylbenzaldehyde, 0.2 mol of acetophenone, 0.11 mol of ammonium acetate, 0.35 g of 10% Cusalen / MIL-100 (Fe) prepared in Example 1, and 30 mL of ethanol were added. The mixture was then stirred at 70 °C for 2 hours. After the reaction was complete, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the lower catalyst layer was recovered. After drying, the catalyst could be reused for the next batch of catalytic reactions. The upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a purified solid product with a yield of 97%. 1 H NMR analysis is shown in Figure 4 The purity is 99.0%.
[0039] Example 14 This invention provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, 0.1 mol of o-methoxybenzaldehyde, 0.2 mol of acetophenone, 0.11 mol of ammonium acetate, 0.35 g of 10% Cusalen / MIL-100 (Fe) prepared in Example 1, and 30 mL of ethanol were added. The mixture was then stirred at 70 °C for 2 hours. After the reaction was complete, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the lower catalyst layer was recovered. After drying, the catalyst could be reused for the next batch of catalytic reactions. The upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a purified solid product with a yield of 95%. 1 H NMR analysis is shown in Figure 5 The purity is 98.6%.
[0040] Example 15 This invention provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, 0.1 mol of p-nitrobenzaldehyde, 0.2 mol of acetophenone, 0.11 mol of ammonium acetate, 0.35 g of 10% Cusalen / MIL-100 (Fe) prepared in Example 1, and 30 mL of ethanol were added. The mixture was then stirred at 70 °C for 3 hours. After the reaction was complete, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the lower catalyst layer was recovered. After drying, the catalyst could be reused for the next batch of catalytic reactions. The upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a purified solid product with a yield of 91%. 1 H NMR analysis is shown in Figure 6 The purity is 98.4%.
[0041] Example 16 This invention provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, 0.1 mol of p-chlorobenzaldehyde, 0.2 mol of acetophenone, 0.11 mol of ammonium acetate, 0.35 g of 10% Cusalen / MIL-100 (Fe) prepared in Example 1, and 30 mL of ethanol were added. The mixture was then stirred at 70 °C for 3 hours. After the reaction was complete, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the lower catalyst layer was recovered. After drying, the catalyst could be reused for the next batch of catalytic reactions. The upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a purified solid product with a yield of 93%. 1 H NMR analysis is shown in Figure 7 The purity is 98.2%.
[0042] Example 17 The catalyst recovered after the reaction in Example 9 was completed, and the catalytic reaction was carried out again according to the method of Example 9 to prepare 2,4,6-triarylpyridine compounds. The recovered catalyst was reused 5 times. Experimental results showed that the activity of the recovered catalyst was not reduced, and the product yields were 96%, 94%, 93%, 91%, and 90%, respectively. 1 ¹H NMR analysis showed purities of 98.7%, 98.5%, 98.2%, 98.1%, and 98.0%, respectively.
[0043] Figure 1 These are SEM images of the catalyst 10% Cusalen / MIL-100 (Fe) before the reaction (a) and after 5 recycling cycles (b), based on... Figure 1 It can be seen that the morphology of the 10% Cusalen / MIL-100 (Fe) catalyst did not change significantly after five recycling cycles, proving that the catalyst has good stability.
[0044] Figure 2 These are EDX graphs of the catalyst 10% Cusalen / MIL-100 (Fe) before the reaction (a) and after 5 recycling cycles (b), based on... Figure 2 It can be seen that after five recycling cycles, the 10% Cusalen / MIL-100 (Fe) element in the catalyst did not change significantly, proving that the catalyst has good stability.
[0045] Comparative Example 1 Comparative Example 1 provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, benzaldehyde (0.1 mol), acetophenone (0.2 mol), ammonium acetate (0.15 mol), Cusalen (0.5 g), and ethanol (30 mL) were added, and the mixture was stirred at 80 °C for 12 hours. After the reaction was complete, the mixture was cooled to room temperature, allowed to stand and separate into layers, the lower catalyst layer was recovered, and the upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a solid product with a yield of 53%. 1 ¹H NMR analysis showed a purity of 85.2%.
[0046] Comparative Example 2 Comparative Example 2 provides a method for preparing 2,4,6-triarylpyridine compounds, specifically including: In a reaction flask, benzaldehyde (0.1 mol), acetophenone (0.2 mol), ammonium acetate (0.15 mol), MIL-100(Fe) (0.5 g) prepared in step S2 of Example 1, and ethanol (30 mL) were added, and the mixture was stirred at 80 °C for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the lower catalyst layer was recovered. After drying, the catalyst could be recycled for reuse in the next batch of catalytic reactions. The upper product phase was distilled to recover the solvent. The obtained crude solid product was recrystallized from ethanol, and the collected crystals were dried to obtain a purified solid product with a yield of 42%. 1 ¹H NMR analysis showed a purity of 80.3%.
[0047] The metal-organic framework / metal Schiff base nanocomposite material Cusalen / MIL-100(Fe) prepared in this invention exhibits high catalytic activity and can effectively promote the reaction. Simultaneously, this catalyst possesses good stability, is easy to separate and recover from the reaction system, and its catalytic performance remains essentially unchanged after multiple cycles, still stably exerting its catalytic effect, demonstrating good reusability.
[0048] This invention uses aromatic aldehydes, aromatic ketones, and nitrogen-containing compounds as starting materials and employs the catalyst Cusalen / MIL-100 (Fe) to achieve a one-step condensation reaction to prepare 2,4,6-triarylpyridine compounds. The entire reaction process is simple to operate, does not use toxic or harmful reagents, and is friendly to operators and the environment. Furthermore, this reaction route is highly efficient, yielding ideal results for the target product, aligning with the principles of green chemistry.
[0049] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.
Claims
1. A catalyst for the synthesis of 2,4,6-triarylpyridine compounds, characterized in that, The catalyst is a MIL-100(Fe) / bis(salicylaldehyde) ethylenediamine copper composite material, and its preparation method includes the following steps: Salicylaldehyde, ethylenediamine and solvent were mixed and heated to react, yielding H2salen ligand; Ferric nitrate, pyromellitic acid and solvent were mixed and heated to react, yielding MIL-100 (Fe). Copper acetate, MIL-100(Fe) and solvent are mixed. After the reaction is complete, MIL-100(Fe) impregnated with copper ions is obtained. The catalyst was obtained by mixing H2salen ligand, MIL-100 (Fe) impregnated with copper ions, and solvent, and then heating the mixture.
2. The catalyst according to claim 1, characterized in that, The molar ratio of salicylaldehyde to ethylenediamine is (1.5~2.5):1; the reaction temperature of salicylaldehyde and ethylenediamine is 70~80℃, and the reaction time is 1~3 h.
3. The catalyst according to claim 1, characterized in that, The molar ratio of ferric nitrate to trimellitic acid is (1.5~2.5):1; the reaction temperature of ferric nitrate and trimellitic acid is 150~160 ℃, and the reaction time is 10~15 h.
4. The catalyst according to claim 1, characterized in that, The mass ratio of copper acetate to MIL-100 (Fe) is (4~12):100; the reaction temperature of copper acetate and MIL-100 (Fe) is 20~30 ℃, and the reaction time is 10~15 h.
5. The catalyst according to claim 1, characterized in that, The mass ratio of the H2salen ligand to the copper-impregnated MIL-100 (Fe) is (1~2):1; the reaction temperature of the H2salen ligand and the copper-impregnated ions is 70~80 ℃, and the reaction time is 20~25 h.
6. The catalyst according to claim 1, characterized in that, Ethanol is used as the solvent in the preparation of H2salen ligands; The solvent used in the preparation of MIL-100 (Fe) is deionized water; Ethanol is used as the solvent in the preparation of MIL-100 (Fe) impregnated with copper ions; The solvent used in the preparation of the catalyst via H2salen ligand and MIL-100(Fe) impregnated with copper ions is acetone.
7. A method for preparing a 2,4,6-triarylpyridine compound, characterized in that, Using aromatic aldehydes, aromatic ketones, and a nitrogen source as raw materials, a mixed reaction is carried out under the action of a catalyst to generate 2,4,6-triarylpyridine compounds; the catalyst is the catalyst described in any one of claims 1 to 6.
8. The method for preparing 2,4,6-triarylpyridine compounds according to claim 7, characterized in that, The molar ratio of the aromatic aldehydes, aromatic ketones and nitrogen source is 1:2:(1~1.5), and the mass of the catalyst is 0.1~2% of the total mass of the raw materials.
9. The method for preparing 2,4,6-triarylpyridine compounds according to claim 7, characterized in that, The reaction temperature is 40~80 ℃, and the reaction time is 1~5 h.
10. The method for preparing 2,4,6-triarylpyridine compounds according to claim 7, characterized in that, The aromatic aldehydes are benzaldehyde, p-methylbenzaldehyde, o-methoxybenzaldehyde, p-nitrobenzaldehyde, or p-chlorobenzaldehyde; the aromatic ketones are acetophenone; and the nitrogen source is ammonium acetate.