A zirconium-based porous metal organic framework catalyst, a preparation method and application thereof

Abstract

The application discloses a zirconium-based porous metal organic framework catalyst, a preparation method and application. The catalyst is an MOF808 catalyst prepared from Zr salt and 1,3,5-benzene tricarboxylic acid in a molar ratio of 1:1. The catalyst, benzoic acid, benzylamine and a reaction solvent are placed in a reaction container, and an amine acid condensation reaction is carried out under nitrogen protection to obtain N-benzyl benzamide. The reaction temperature of the amine acid condensation reaction is 40-120 DEG C, and the reaction time is 2-24 h. The catalyst can efficiently and selectively condense benzoic acid and benzylamine to prepare N-benzyl benzamide under the condition that the reaction temperature is 90 DEG C and the solvent is tetrahydrofuran, and has the advantages of high conversion efficiency, good product selectivity, mild reaction condition, easy recycling and the like.

Description

A zirconium-based porous metal-organic framework catalyst, its preparation method and application Technical Field

[0001] This invention relates to the field of chemical technology for the efficient catalytic conversion of biomass platform compounds into high-value chemicals, and in particular to a zirconium-based porous metal-organic framework catalyst, its preparation method, and its application in the process of amide preparation by amino acid condensation. Background Technology

[0002] Amides are a crucial biomass platform compound with wide applications in pharmaceuticals, pesticides, materials, and food additives. In-depth analysis of the Comprehensive Medicinal Chemistry Database reveals that over 25% of known drugs contain amide structural units. Common drugs such as loperamide (acetaminophen, an analgesic), lidocaine (Xylocaine, a local anesthetic), and atorvastatin (a cholesterol-lowering agent) all contain amide structures. Furthermore, amides are widely present in the structures of potential drug compounds. Amide compounds are also widely used in papermaking, plastics, rubber, and agriculture, and serve as important intermediates in the synthesis of therapeutic agents.

[0003] Currently, amino acid condensation catalysts are classified into two types: homogeneous and heterogeneous. Heterogeneous catalysts are mostly composed of commercially available inorganic oxides such as Nb₂O₅, Al₂O₃, ZrO₂, SiO₂, and TiO₂. Although they are easy to separate and recover, the formation of water during the reaction reduces their catalytic activity, making them unsuitable for repeated and effective utilization. Homogeneous catalysts are generally complex organic compounds. While they offer high reaction efficiency, they are expensive, have low atom utilization, and produce numerous toxic and harmful byproducts, thus failing to meet green chemistry standards. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in the background technology by proposing a zirconium-based porous metal-organic framework catalyst, its preparation method, and its application in the process of amide preparation by amino acid condensation. This invention constructs a highly efficient and mild catalytic system for the condensation reaction of benzoic acid and benzylamine to prepare amide, effectively solving the problems of heterogeneous catalysts not being reusable and catalyst deactivation caused by free water.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing a zirconium-based porous metal-organic framework catalyst, comprising:

[0007] Zr salt and 1,3,5-benzenetricarboxylic acid were mixed in a solvent and stirred at room temperature to form a homogeneous gel; the molar ratio of Zr salt to 1,3,5-benzenetricarboxylic acid was 1:1.

[0008] A uniform gel was subjected to a hydrothermal reaction to obtain a white granular solid.

[0009] The zirconium-based porous metal-organic framework catalyst was obtained by freeze-drying, grinding, and sieving a white granular solid.

[0010] Furthermore, the Zr salt is either zirconium chloride or zirconium oxide chloride.

[0011] Furthermore, the solvent is a mixture of N,N-dimethylformamide and formic acid solutions in a molar ratio of 1:1.

[0012] In a second aspect, the present invention provides a zirconium-based porous metal-organic framework catalyst, which is prepared by the method for preparing zirconium-based porous metal-organic framework catalysts as described in any one of the first aspects.

[0013] Thirdly, the present invention provides the application of the aforementioned zirconium-based porous metal-organic framework catalyst in the process of preparing amides by amino acid condensation.

[0014] Furthermore, the application of the zirconium-based porous metal-organic framework catalyst in the process of preparing amide by amino acid condensation includes: placing the zirconium-based porous metal-organic framework catalyst, benzoic acid, benzylamine and reaction solvent in a reaction vessel, and carrying out an amino acid condensation reaction under nitrogen protection to obtain N-benzylbenzamide.

[0015] Furthermore, the reaction temperature for the amino acid condensation reaction is 40~120℃, and the reaction time is 2~24h.

[0016] Preferably, the reaction temperature for the amino acid condensation reaction is 70~90℃, and the reaction time is 8~12h.

[0017] Furthermore, the reaction solvent for the amino acid condensation reaction is any one of tetrahydrofuran, 1,4-dioxane, and toluene, or a mixture of two or more of tetrahydrofuran, ethyl acetate, 1,4-dioxane, ethanol, N,N-dimethylformamide, and toluene.

[0018] Preferably, the reaction solvent for the amino acid condensation reaction is either tetrahydrofuran or toluene.

[0019] Reaction Mechanism: An intermediate is activated by the interaction of MOF808 with the carbonyl group of a carboxylic acid, followed by nucleophilic addition of an equal amount of amine to this intermediate. Subsequently, excess free amine continues to add to the intermediate, forming a cyclic compound. Finally, the unstable cyclic compound removes water molecules to form the target product, the amide.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention prepared MOF808 catalyst by a simple hydrothermal synthesis method. The preparation process is simple and the synthesis route is short. By controlling the active components of the catalyst, the process conditions for the amino acid condensation of benzoic acid and benzylamine to prepare amide were optimized, and a reaction catalytic system for amino acid condensation to prepare amide was constructed, which effectively solved the problem that the catalyst cannot be reused in the preparation of amide.

[0022] (2) The catalyst of the present invention can efficiently and selectively condense benzoic acid and benzylamine to prepare N-benzylbenzamide under the conditions of reaction temperature of 90°C and reaction solvent of tetrahydrofuran (THF), and has the advantages of high conversion efficiency, good product selectivity, mild reaction conditions and easy recycling. Attached Figure Description

[0023] Figure 1 shows the chemical reaction formula for the preparation of amides by amino acid condensation of benzoic acid and benzylamine in this invention. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments. These embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0025] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0026] Unless otherwise specified, all raw materials used in the embodiments of this invention were purchased through commercial channels.

[0027] Example 1

[0028] A method for preparing a zirconium-based porous metal-organic framework catalyst includes the following steps:

[0029] S1. Mix 4 mmol of zirconium chloride, 4 mmol of 1,3,5-benzenetricarboxylic acid, 16 mL of N,N-dimethylformamide solution, and 16 mL of formic acid solution in a solvent, and then stir at room temperature of 20~30℃ for 1-2 hours to form a uniform gel.

[0030] S2. Place the uniform gel obtained in S1 into a polytetrafluoroethylene-lined hydrothermal synthesis reactor and heat it at a constant temperature of 120°C for 48 hours. After the reaction is completed, wait for the hydrothermal reactor to cool to room temperature, filter and collect the white granular solid, and wash it several times with N,N-dimethylformamide solution to remove unreacted ligand molecules.

[0031] S3. The white granular solid obtained in S2 is freeze-dried, ground, and sieved to obtain zirconium-based porous metal-organic framework catalyst MOF808.

[0032] Example 2

[0033] The catalyst MOF808 prepared in Example 1 was applied to the amino acid condensation reaction of benzoic acid and benzylamine, comprising the following steps: 10 mg of catalyst, 1 mmol of benzoic acid, 2 mmol of benzylamine, 0.5 g of 4A molecular sieve, and 2.5 mL of tetrahydrofuran (THF) reaction solvent were placed in a 15 mL reaction tube and sealed. A double-row tube was used to evacuate the system and introduce nitrogen gas at a certain pressure. The reaction temperature was set to 90 °C and maintained at 90 °C for 48 h. The stirring rate was 300 rpm. After the set reaction time, the reaction tube was allowed to cool naturally, and the mixture of reaction solution and catalyst was poured out. The catalyst in the above reaction solution was fixed by filtration through a funnel, and the clear reaction solution was poured out to obtain the catalyst after the reaction.

[0034] Comparative Examples 1-2

[0035] Commercially available ZrO2 and ZrCl4 catalysts were applied to the amino acid condensation reaction of benzoic acid and benzylamine, respectively, including the following steps: 10 mg of catalyst, 1 mmol of benzoic acid, 2 mmol of benzylamine, 0.5 g of 4A molecular sieve, and 2.5 mL of reaction solvent THF were placed in a 15 mL reaction tube and sealed. A double-row tube was used to evacuate the system and introduce nitrogen gas at a certain pressure. The reaction temperature was set to 90 °C and maintained at 90 °C for 48 h. The stirring rate was 300 rpm. After the set reaction time, the reaction tube was allowed to cool naturally, and the mixture of reaction solution and catalyst was poured out. The catalyst in the reaction solution was fixed by filtration through a funnel, and the clear reaction solution was poured out to obtain the catalyst after the reaction.

[0036] The reaction products in the reaction solutions of Examples 2, 1, and 2 were purified by GC and column chromatography, and the yields of the target product amide were obtained. The results are shown in Table 1.

[0037] Table 1. Selectivity comparison of amide products in amino acid condensation

[0038] Case Catalyst Reaction Conditions Amine Yield (%) Comparative Example 1 ZrO2 90℃, 48h 27.2 Comparative Example 2 ZrCl4 90℃, 48h 82 Example 2 MOF80 890℃, 48h 67.9 surface

[0039] Examples 2 and Comparative Examples 1 and 2 aim to investigate the effects of Zr-based catalysts and the MOF808 catalyst prepared in this invention on the performance of the amino acid condensation reaction of benzoic acid and benzylamine. Table 1 shows that different catalysts have a significant impact on the performance of the amino acid condensation reaction. ZrO2, ZrCl4, and MOF808 catalysts all exhibit reactivity, with ZrCl4 showing the best effect. However, ZrCl4 is prone to deliquescence when exposed to water and cannot be reused. ZrO2 shows the worst effect. While the MOF808 catalyst of this invention has lower reactivity than ZrCl4, it can be reused multiple times, and its reactivity is only slightly lower than that of ZrCl4.

[0040] Examples 3-10

[0041] The catalyst prepared in Example 1 was applied to the amino acid condensation reaction of benzoic acid and aniline, respectively, including the following steps: 10 mg of catalyst, 1 mmol of benzoic acid, 2 mmol of aniline, 0.5 g of 4A molecular sieve, and 2.5 mL of different reaction solvents were placed in a 15 mL reaction tube and sealed. A double-row tube was used to evacuate the system and introduce nitrogen gas at a certain pressure. The reaction temperature was set to 90 °C and maintained at 90 °C for 8 hours. The stirring rate was 300 rpm. After the set reaction time, the reaction tube was allowed to cool naturally, and the mixture of reaction solution and catalyst was poured out. The catalyst in the above reaction solution was fixed by filtration through a funnel, and the clear reaction solution was poured out to obtain the catalyst after the reaction.

[0042] The reaction products in the reaction solutions of Examples 3-10 were purified qualitatively and quantitatively by GC and column chromatography to obtain the yield of the target product amide. The results are shown in Table 2:

[0043] Table 2: Selectivity Comparison of Amide Products in Acid Condensation

[0044] Example Solvent Reaction Conditions Amine Yield (%) 3 Tetrahydrofuran 90℃, 8h 57.04 Toluene 90℃, 8h 53.45 N,N-Dimethylformamide 90℃, 8h 26.16 Tetrahydrofuran:water (1:1) 90℃, 8h 24.37 Tetrahydrofuran:ethanol (1:1) 90℃, 8h 43.68 Ethyl acetate 90℃, 8h 16.49 Ethanol 90℃, 8h 3.410 1,4-Dioxane 90℃, 8h 33.7 surface

[0045] Examples 3-10 aim to investigate the effect of different solvents on the catalytic performance of the MOF808 catalyst in the amino acid condensation reaction of benzoic acid and benzylamine. Table 2 shows that the solvent has a significant impact on the catalytic performance of the MOF808 catalyst in this reaction. The yield of the target product, N-benzylbenzamide, varies considerably between single solvents such as tetrahydrofuran, toluene, N,N-dimethylformamide, and ethanol, and between mixed solvents such as tetrahydrofuran:water (1:1) and tetrahydrofuran:ethanol (1:1). Using tetrahydrofuran as the solvent, under relatively mild reaction conditions (90°C, 8 h), the yield of the target product amide reached 57.0%, indicating that this aprotic, nonpolar solvent promotes the amino acid condensation reaction. However, when water was introduced into tetrahydrofuran, the yield of the target product amide decreased to 24.3%, indicating that the introduction of water is detrimental to the amino acid condensation reaction. When ethanol is used as a reaction solvent, the yield of the target product amide is low, only 3.4%. However, when ethanol is mixed with tetrahydrofuran as a solvent, the yield of amide can reach 43.6%.

[0046] Examples 11-16

[0047] The catalyst prepared in Example 1 was applied to the amino acid condensation reaction of benzoic acid and benzylamine, respectively, including the following steps: 10 mg of catalyst, 1 mmol of benzoic acid, 2 mmol of benzylamine, 0.5 g of 4A molecular sieve, and 2.5 mL of tetrahydrofuran solvent were placed in a 15 mL reaction tube and sealed. A double-row tube was used to evacuate the system and introduce nitrogen gas at a certain pressure. Different reaction temperatures were set and maintained at these temperatures for different reaction times. The stirring rate was 300 rpm. After the set reaction time, the reaction tube was allowed to cool naturally, and the mixture of reaction solution and catalyst was poured out. The catalyst in the above reaction solution was fixed by filtration through a funnel, and the clear reaction solution was poured out to obtain the catalyst after the reaction.

[0048] The reaction products in the reaction solutions of Examples 11-16 were purified qualitatively and quantitatively by GC and column chromatography to obtain the yield of the target product amide. The results are shown in Table 3:

[0049] Table 3: Selectivity Comparison of Amide Products in Acid Condensation

[0050] Example Solvent Reaction Conditions Amine Yield (%) 11 Tetrahydrofuran 50℃, 12h 35.1 12 Tetrahydrofuran 70℃, 12h 52.3 13 Tetrahydrofuran 90℃, 12h 64.0 14 Tetrahydrofuran 110℃, 12h 67.2 15 Tetrahydrofuran 90℃, 4h 10.9 16 Tetrahydrofuran 90℃, 8h 57.0 surface

[0051] The purpose of Examples 11-16 was to investigate the effects of reaction conditions, such as temperature and reaction time, on the catalytic performance of the MOF808 catalyst in the amino acid condensation reaction of benzoic acid and benzylamine. Table 3 shows that the reaction conditions have a significant impact on the catalytic performance of the MOF808 catalyst in the amino acid condensation reaction of benzoic acid and benzylamine. Under relatively mild reaction conditions (90℃, 12h), the yield of the target product amide reached 67.2%. Compared to the high-temperature environment of 110℃ in Example 14, Example 13 is more energy-efficient and environmentally friendly, conforming to green chemistry standards.

[0052] Examples 17-21

[0053] The catalyst prepared in Example 1 was applied to the amino acid condensation reaction of benzoic acid and aniline, respectively, including the following steps: 10 mg of catalyst, 1 mmol of benzoic acid, 2 mmol of aniline, 0.5 g of 4A molecular sieve, and 2.5 mL of tetrahydrofuran solvent were placed in a 15 mL reaction tube and sealed. A double-row tube was used to evacuate the system and introduce nitrogen gas at a certain pressure. The reaction temperature was set to 90 °C and maintained at 90 °C for 12 h. The stirring rate was 300 rpm. After the set reaction time, the reaction tube was allowed to cool naturally, and the mixture of reaction solution and catalyst was poured out. The catalyst in the above reaction solution was fixed by filtration through a funnel, and the clear reaction solution was poured out to obtain the catalyst after the reaction. The catalyst was reused multiple times, as in Examples 18-21.

[0054] The reaction products in the reaction solutions of Examples 17-21 were purified qualitatively and quantitatively by GC and column chromatography to obtain the yield of the target product amide. The results are shown in Table 4:

[0055] Table 4: Selectivity Comparison of Acid Condensation with Amid Products

[0056] Example Catalyst Reaction Time Reaction Conditions Amine Yield (%) 17 12h 90℃, 12h 64.0 18 24h 90℃, 12h 62.1 19 48h 90℃, 12h 59.8 20 60h 90℃, 12h 54.2 21 72h 90℃, 12h 50.6 surface

[0057] The purpose of Examples 17-21 was to investigate the reusability of the amide condensation reaction of benzoic acid and benzylamine catalyzed by the MOF808 catalyst. As shown in Table 4, with prolonged use of the MOF808 catalyst, the yield of the target product amide gradually decreased, but the overall yield remained above 50%. The MOF808 catalyst can be used at least five times, demonstrating good recyclability.

[0058] The present invention has been disclosed above with reference to preferred embodiments, but it is not intended to limit the present invention. All technical solutions obtained by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the present invention.

Claims

1. The application of zirconium-based porous metal-organic framework catalysts in the process of preparing amides by amino acid condensation, characterized in that, The amine is benzylamine, the acid is benzoic acid, and the preparation method of the zirconium-based porous metal-organic framework catalyst includes: mixing zirconium chloride and 1,3,5-benzenetricarboxylic acid in a solvent and stirring at room temperature for 1-2 hours to form a uniform gel; the molar ratio of zirconium chloride to 1,3,5-benzenetricarboxylic acid is 1:1; the solvent is a mixture of N,N-dimethylformamide and formic acid in a molar ratio of 1:1; placing the uniform gel in a polytetrafluoroethylene-lined hydrothermal synthesis reactor and performing a hydrothermal reaction at 120°C for 48 hours to obtain a white granular solid; and freeze-drying, grinding, and sieving the white granular solid to obtain the zirconium-based porous metal-organic framework catalyst.

2. The application according to claim 1, characterized in that, A zirconium-based porous metal-organic framework catalyst, benzoic acid, benzylamine, and a reaction solvent were placed in a reaction vessel and subjected to an amino acid condensation reaction under nitrogen protection to obtain N-benzylbenzamide.

3. The application according to claim 2, characterized in that, The reaction temperature for amino acid condensation is 40~120℃, and the reaction time is 2~24h.

4. The application according to claim 3, characterized in that, The reaction temperature for amino acid condensation is 70~90℃, and the reaction time is 8~12h.

5. The application according to claim 2, characterized in that, The reaction solvent for the amino acid condensation reaction is any one of tetrahydrofuran, 1,4-dioxane, and toluene, or a mixture of two or more of tetrahydrofuran, ethyl acetate, 1,4-dioxane, ethanol, N,N-dimethylformamide, and toluene.

6. The application according to claim 5, characterized in that, The reaction solvent for the amino acid condensation reaction is either tetrahydrofuran or toluene.

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