Process for the preparation of n-substituted pyrrole compounds

Abstract

The application relates to a preparation method of an N-substituted pyrrole compound, which comprises the following steps: contacting 2,5-hexanedione and / or a furan compound with an amine compound in the presence of a liquid-phase diluent and a catalyst; the catalyst contains a metal organic framework material, the metal organic framework material comprises the following: a metal center; and an organic ligand coordinated with a binding site of the metal center to form an at least partially crystalline network structure with multiple internal pores; the metal of the metal center is selected from at least one of Zn, Zr, V, Cr, Fe, Co, Ni, Cu, Ag, Cd and Al; and the organic ligand is selected from at least one of a carboxylic acid organic ligand and / or a polyazolate organic ligand. The N-substituted pyrrole compound is prepared by the metal organic framework material catalysis for the first time, and high efficiency of the reaction and high yield of the product can be realized.

Description

Technical Field

[0001] This invention relates to a method for preparing N-substituted pyrrole compounds. Background Technology

[0002] To achieve sustainable economic development, the development of renewable lignocellulosic biomass to replace fossil fuels in the production of carbon-containing chemicals and fuels has attracted increasing attention. These are the only widely available carbon sources besides oil and coal, and can be relatively easily converted into several important platform compounds with many useful chemical bonds, such as nitrogen heterocycles.

[0003] Nitrogen-containing heterocycles, especially functionalized pyrroles, are important structural units in a large number of naturally occurring and pharmacologically active molecules, and are widely used in the core structures of bioactive substances such as vitamins, anticancer drugs, and antibacterial drugs. The main traditional pathways for N-substituted pyrroles typically use substituted ketones, aldehydes, or amines as substrates, most of which are derived from petrochemical resources, and the reaction yields are relatively low. 2,5-Hexanedione (HDO) or 2,5-dimethylfuran (DMF) have attracted increasing attention as important biomass platform compounds, and researchers have synthesized HDO or DMF through cellulose or sugar platforms. HDO or DMF can undergo Paal-Knorr condensation reactions with amines or nitro compounds under appropriate catalysts to generate N-substituted pyrroles, achieving high selectivity and yield under suitable catalysts and reaction conditions. Patent document CN103288701A discloses a 1,5-diarylpyrrole derivative, which is prepared by reacting a 1,4-dicarbonyl compound with an amine compound under the catalysis of a protic acid. The yield of most examples is around 40-60%.

[0004] The prior art [New J. Chem. 2017, 21, 12339-13184] proposes an efficient method for synthesizing pyrrole using a deep eutectic solvent-based [CholineCl][ZnCl2]3 under ultrasonic irradiation. This method can achieve a high yield, but it is not suitable for large-scale production due to its high energy consumption and the need for a eutectic solvent. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of low product selectivity of N-substituted pyrrole compounds or the need for expensive metal catalysts in the existing technology, and to provide a method for preparing N-substituted pyrrole compounds; the preparation of N-substituted pyrrole compounds by catalysis of metal-organic framework materials has the outstanding characteristics of high reaction efficiency and high product yield.

[0006] To achieve the above objectives, the present invention provides a method for preparing N-substituted pyrrole compounds, the method comprising:

[0007] In the presence of a liquid diluent and a catalyst, 2,5-hexanedione and / or furans are contacted with amine compounds;

[0008] The catalyst contains a metal-organic framework material, which includes:

[0009] Metal center; and

[0010] Organic ligands coordinated to binding sites at the metal center to form a network structure with at least partial crystallization and multiple internal pores;

[0011] The metal at the metal center is selected from at least one of Zn, Zr, V, Cr, Fe, Co, Ni, Cu, Ag, Cd, and Al; the organic ligand is selected from at least one of carboxylic acid organic ligands and / or polyazole organic ligands.

[0012] Through the above technical solution, this invention achieves, for the first time, the catalytic preparation of N-substituted pyrrole compounds (e.g., 2,5-dimethyl N-substituted pyrrole compounds) using metal-organic framework materials, realizing high reaction efficiency and high product yield. The development of this method will provide new ideas for the green synthesis of pyrrole compounds and offer new directions for metal-organic framework materials in the field of biomass catalysis, achieving unexpected technical results. Attached Figure Description

[0013] Figure 1 The images are scanning electron microscope (SEM) images of Cu-BTC and Cu-BTC-BzIm from Example 1.

[0014] Figure 2 The image shows the pyridine desorption infrared (Py-FTIR) images of Cu-BTC and Cu-BTC-BzIm in Example 1.

[0015] Figure 3 The contact angle between Cu-BTC and water in Example 1;

[0016] Figure 4 The contact angle between Cu-BTC-BzIm and water in Example 1;

[0017] Figure 5 The N2- adsorption / desorption curves of Cu-BTC and Cu-BTC-BzIm in Example 1 are shown.

[0018] Figure 6 This is a scanning electron microscope (SEM) image of Cu-BTC-BzIm-2 in Example 2;

[0019] Figure 7 The infrared spectrum of pyridine desorption for Cu-BTC and Fe-Cu-BTC prepared in Example 11;

[0020] Figure 8 The XRD patterns are of Cu-BTC and Fe-Cu-BTC obtained in Example 11. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] In this invention, MOFs materials refer to metal-organic framework materials or metal-organic skeleton materials.

[0023] In this invention, the metal center refers to the metal ion used to form the coordination complex in MOF materials.

[0024] This invention provides a method for preparing an N-substituted pyrrole compound, the method comprising:

[0025] In the presence of a liquid diluent and a catalyst, 2,5-hexanedione and / or furans are contacted with amine compounds;

[0026] The catalyst contains a metal-organic framework material, which includes:

[0027] Metal center; and

[0028] Organic ligands coordinated to binding sites at the metal center to form a network structure with at least partial crystallization and multiple internal pores;

[0029] The metal at the metal center is selected from at least one of Zn, Zr, V, Cr, Fe, Co, Ni, Cu, Ag, Cd, and Al; the organic ligand is selected from at least one of carboxylic acid organic ligands and / or polyazole organic ligands.

[0030] The preparation of N-substituted pyrrole compounds using metal-organic framework materials as catalysts can achieve high reaction efficiency and high product yield.

[0031] According to a preferred embodiment of the present invention, the metal in the metal center is selected from at least one of Zn, Cu, Ni, Fe, Co, Ag and Zr.

[0032] According to a preferred embodiment of the present invention, the carboxylic acid organic ligand is selected from at least one of pyromellitic acid, terephthalic acid, phthalic acid, biphenyl-3,4,5-tricarboxylic acid, 1,4-naphthalenedicarboxylic acid, biphenyl dicarboxylic acid, and 3,3,5,5-biphenyltetracarboxylic acid.

[0033] According to a preferred embodiment of the present invention, the polyazole organic ligand is selected from at least one of benzimidazole, 2-methylbenzimidazole, 5,6-dimethylbenzimidazole, 2-(2-hydroxybenzyl)benzimidazole, 2-aminobenzimidazole and 2-(4'-thiazole)benzimidazole.

[0034] According to a preferred embodiment of the present invention, the metal-organic framework material is a dual-ligand MOF material, comprising:

[0035] Metal center; and

[0036] Carboxylic acid organic ligands and polyazole organic ligands coordinated to at least two binding sites of the metal center form a partially crystalline network structure with multiple internal pores. The use of these dual-ligand MOFs materials is beneficial for improving conversion and selectivity.

[0037] According to a preferred embodiment of the present invention, the contact angle between the dual-ligand MOF material and water is 40-120°, preferably 40-100°.

[0038] According to a preferred embodiment of the present invention, the dual-ligand MOF material crystal has a wrinkled outer surface; preferably, the surface of the dual-ligand MOF material crystal has clusters of sheet-like protrusions forming a wrinkled outer surface.

[0039] According to a preferred embodiment of the present invention, the total acidity of the dual-ligand MOF material is 30-500 μmol·g. -1 Preferably, it is 40-400 μmol·g -1 .

[0040] According to a preferred embodiment of the present invention, the total specific surface area of ​​the dual-ligand MOFs material is 900-1800 m². 2 ·g -1 External specific surface area is 40-200m² 2 ·g -1 .

[0041] According to a preferred embodiment of the present invention, the total pore volume of the dual-ligand MOFs material is 0.4-1.0 cm³. 3 ·g -1 The micropore volume is 0.2-0.9 cm³. 3 ·g -1 .

[0042] In this invention, the total pore volume of the dual-ligand MOFs material is the sum of the micropore volume and the mesopore volume.

[0043] Dual-ligand MOFs materials possessing the aforementioned features of this invention can all achieve the objectives of this invention, and there are no special requirements for their preparation methods. In accordance with a preferred embodiment of this invention, this invention provides a method for preparing the dual-ligand MOFs material described herein, the method comprising the following steps:

[0044] S1. Dissolve soluble metal salts and carboxylic acid organic ligands in solvent I, crystallize, separate, and first dry to obtain MOF materials formed by metal and organic ligand I;

[0045] S2. Contact the MOFs material from step S1 with a solution containing polyazole organic ligands and alkaline substances; separate, wash, and perform a second drying to obtain the dual-ligand MOFs material.

[0046] In the preparation process of the dual-ligand MOFs material described in this invention, coordinated water molecules are easily removed, forming open metal centers as catalytic centers. Through ligand exchange, the strong basicity of polyazole ligands containing benzene rings makes the pore surface properties of the dual-ligand MOFs material easier to control. Nitrogen atom donors participate in coordination, thus exhibiting a certain degree of hydrophobicity compared to before ligand exchange. The newly formed open metal sites increase the acidity of the material, and the newly formed mesoporous cavities effectively promote substrate diffusion, which not only facilitates substrate adsorption and product desorption, increasing the yield of the target product, but also inhibits catalyst deactivation.

[0047] In this invention, there is no particular limitation on the type of soluble metal salt, such as soluble salts of metal nitrates, metal chlorides, metal sulfates, etc.

[0048] In this invention, the ratio of the soluble metal salt to the organic ligand I in step S1 can be selected over a wide range. According to a preferred embodiment of this invention, the molar ratio of the soluble metal salt to the organic ligand I is 1:0.2-5.

[0049] In this invention, the ratio of solvent I to soluble metal salt in step S1 can be selected from a wide range. According to a preferred embodiment of this invention, the ratio of solvent I to soluble metal salt is 5-100 mL solvent I / 1.0 g soluble metal salt.

[0050] In this invention, the ratio of MOF materials to organic ligand II in step S2 can be selected from a wide range. According to a preferred embodiment of this invention, the molar ratio of MOF materials to organic ligand II is 1:(0.01-5).

[0051] In this invention, the range of possible ratios of MOFs material to alkaline substance in step S2 is relatively wide. According to a preferred embodiment of this invention, the molar ratio of MOFs material to alkaline substance is 1:(0.01-3).

[0052] In this invention, in step S2, the solvent in the solution containing organic ligand II and alkaline substance can be selected from a wide range. According to a preferred embodiment of this invention, the solvent is solvent II, which is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, methanol, ethanol, acetone, dichloromethane, toluene, and ethylbenzene. Preferably, the mass ratio of MOFs material to solvent II is 1:(2-200).

[0053] In this invention, the range of alkaline substances that can be selected in step S2 is relatively wide, as long as they are organic bases or inorganic bases with weak alkalinity. According to a preferred embodiment of this invention, the alkaline substance is selected from at least one of triethylamine, trimethylamine, diisopropylethylamine, diethylamine, n-propylamine, n-butylamine, di-n-butylamine, ammonia, and aniline.

[0054] According to a preferred embodiment of the present invention, the method for preparing the metal-organic framework material further includes, in step S2, immersing the washed solid in solvent III, wherein solvent III is selected from at least one of methanol, ethanol, dichloromethane and acetone; the preferred immersion conditions include: immersion temperature of 0-50°C; and mass ratio of solid to solvent III of 1:10-300.

[0055] In this invention, the soaking time can be determined according to actual needs. According to a preferred embodiment of this invention, the soaking time is 10-96 hours, and solvent III is replaced every 2-24 hours.

[0056] In this invention, the crystallization conditions in step S1 can be selected from a wide range. According to a preferred embodiment of this invention, the crystallization conditions include: a crystallization temperature of 30-200℃, preferably 50-160℃; and a reaction time that can be reasonably determined according to actual needs. Preferably, the crystallization time is 3-44h, preferably 5-24h.

[0057] In this invention, the range of selectable first drying conditions in step S1 is relatively wide. According to a preferred embodiment of this invention, the first drying conditions include: a drying temperature of 70-200℃; and a drying time that can be reasonably determined according to actual needs, which is 2-48h. Preferably, the drying is carried out in steps, with the first drying condition including: a temperature of 70-100℃ and a time of 1-24h; and the second drying condition including: a temperature of 120-200℃ and a time of 1-24h.

[0058] In this invention, the range of selectable contact conditions in step S2 is relatively wide. According to a preferred embodiment of this invention, the contact conditions include: a contact temperature of 30-180℃, preferably 50-110℃; and a contact time that can be reasonably determined according to actual needs, preferably 3-30h, preferably 6-20h.

[0059] In this invention, the range of selectable second drying conditions in step S2 is relatively wide. According to a preferred embodiment of this invention, the second drying conditions include: a drying temperature of 70-200℃; the drying time can be reasonably determined according to actual needs, preferably 2-48h; preferably, the drying is carried out in steps, with the first drying condition including: a temperature of 70-100℃ and a time of 1-24h; and the second drying condition including: a temperature of 120-200℃ and a time of 1-24h.

[0060] According to another preferred embodiment of the present invention, the metal-organic framework material is a copper-iron bimetallic MOF material, comprising:

[0061] A bimetallic center formed by Fe and Cu containing two or more valence states; and

[0062] Organic ligands that hybridize with bimetallic centers via coordination bonds to form a three-dimensional network crystal structure. In the copper-iron bimetallic MOFs material of this invention, both metals are bonded to the organic ligands, and due to the interaction between the two metals, the valence states of the metals change, forming more empty coordination sites. The bimetallic MOFs material contains only Lewis acid sites. The copper-iron bimetallic MOFs material of this invention is used to synthesize pyrrole compounds (e.g., N-substituted pyrrole compounds), and also has the advantages of high reaction efficiency and high product yield.

[0063] In this invention, the copper-iron bimetallic MOFs material contains only L-acid, and the amount of L-acid is 100-600 μmol·g. -1 Preferably, it is 150-400 μmol·g -1 .

[0064] In existing technologies, conventional catalytic methods for preparing N-substituted pyrrole compounds use Brønsted acid (protic acid) as a catalyst. This method is susceptible to the influence of the presence or absence of water in the reaction system. However, in this invention, the method for preparing N-substituted pyrrole compounds uses the copper-iron bimetallic MOF material described herein as a catalyst. Since the copper-iron bimetallic MOF material contains only Lewis acid sites, it can catalytically convert furans and amines into N-substituted pyrrole compounds under mild reaction conditions, preventing the formation of byproducts such as 3-methyl-2-cyclopentenone. This method exhibits high selectivity and high product yield. Furthermore, because it uses a catalytic material containing Lewis acid, it is less likely to corrode equipment at high temperatures. Simultaneously, the mild reaction conditions do not damage the structure of the copper-iron bimetallic MOF material, thus providing a new approach to the application of MOFs in catalysis.

[0065] In this invention, the range of organic ligands that can be selected in the copper-iron bimetallic MOFs material is relatively wide. According to a preferred embodiment of this invention, the organic ligand is selected from at least one of the following: trimellitic acid, terephthalic acid, phthalic acid, biphenyl-3,4,5-tricarboxylic acid, 1,4-naphthalenedicarboxylic acid, biphenylic acid, 1,3,5-tris(4-carboxyphenyl)benzene, 4,4,4-tris(N,N-di(4-carboxyphenyl)-amino)triphenylamine, 3,3,5,5-biphenyltetracarboxylic acid, imidazole, 2-methylimidazolium, 2-nitroimidazolium, and 2-nitroimidazolium derivatives; preferably at least one of trimellitic acid and terephthalic acid.

[0066] All copper-iron bimetallic MOFs materials possessing the aforementioned features of this invention can achieve the objectives of this invention, and there are no special requirements for their preparation methods. In accordance with a preferred embodiment of this invention, this invention provides a method for preparing the copper-iron bimetallic MOFs material described herein, the method comprising the following steps:

[0067] (I) Dissolve organic ligands and Cu salts in a solvent, crystallize, separate, and first dry to obtain Cu-based MOFs materials formed by Cu and organic ligands;

[0068] (II) Contact the Cu-based MOFs material from step (I) with an aqueous alcohol mixture containing elemental Fe and Fe salt; separate and perform a second drying to obtain the copper-iron bimetallic MOFs material.

[0069] The preparation method of the copper-iron bimetallic MOFs material of this invention creatively incorporates elemental iron, utilizing the concept of self-reduction of multivalent transition metals. Under the influence of elemental iron, the modified solution acquires reducing properties, maximizing the effectiveness of the reducing components. Furthermore, in addition to its reducing effect, metallic iron provides more vacancy sites, increasing the acidity of the material, resulting in the multivalent copper-iron bimetallic MOFs material containing only L-acids. In the copper-iron bimetallic MOFs material of this invention, metal ions and carboxylic acid ligands form a binuclear metal slurry structure at the nodes. During the preparation process, coordinated water molecules are easily removed, forming open metal centers that serve as catalytic centers.

[0070] In this invention, in step (I), the organic ligand and Cu salt can be dissolved in a solvent to obtain a solution containing the organic ligand and a solution containing the Cu salt, respectively. Then, the solution containing the organic ligand and the solution containing the Cu salt are mixed and reacted to obtain Cu-based MOFs materials.

[0071] In this invention, the crystallization conditions in step (I) can be selected from a wide range. According to a preferred embodiment of this invention, the crystallization conditions include: a crystallization temperature of 30-150℃, preferably 60-110℃; and a reaction time that can be reasonably determined according to actual needs. Preferably, the crystallization time is 3-24h, preferably 10-20h.

[0072] In this invention, in step (I), the range of selectable first drying conditions is relatively wide. According to a preferred embodiment of this invention, the drying conditions include: a drying temperature of 70-200℃, and a drying time of 2-48h that can be reasonably determined according to actual needs; preferably, the drying is carried out in steps, with the first drying condition including: a temperature of 70-100℃ and a time of 1-24h; and the second drying condition including: a temperature of 120-200℃ and a time of 1-24h.

[0073] In this invention, the range of selectable contact conditions in step (II) is relatively wide. According to a preferred embodiment of this invention, the contact conditions include: a contact temperature of 30-150℃, preferably 50-90℃; and a contact time that can be reasonably determined according to actual needs, with a contact time of 3-24h, preferably 3-10h.

[0074] In this invention, the Cu salt is selected from at least one of the soluble salts of metallic Cu.

[0075] In this invention, the Fe salt is selected from at least one of the soluble salts of metallic Fe.

[0076] In this invention, the range of solvents that can be selected in step (I) is relatively wide. According to a preferred embodiment of this invention, the solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, triethylamine, hydrofluoric acid, tetrahydrofuran, methanol, ethanol and deionized water.

[0077] In step (II), the alcohol in the water-alcohol mixture is selected from C1-C5 monohydric or polyhydric alcohols, preferably at least one of methanol, ethanol, propanol and ethylene glycol.

[0078] In this invention, the ratio of solvent to Cu salt in step (I) can be selected from a wide range. According to a preferred embodiment of this invention, the ratio of solvent to salt containing the first metal is 5-100 mL solvent / 1.0 g Cu salt.

[0079] According to a preferred embodiment of the present invention, in step (II), the molar ratio of elemental Fe to soluble Fe salt is 1:0.1-10.

[0080] According to a preferred embodiment of the present invention, in step (II), the ratio of Fe salt used is 5-200 mL solvent / 1.0 g.

[0081] In this invention, the range of types of amine compounds that can be selected is relatively wide. According to a preferred embodiment of this invention, the amine compounds are selected from at least one of aniline, m-chloroaniline, p-methoxyaniline, 3-fluoroaniline, 3-methoxyaniline, m-toluidine, o-toluidine, n-butylamine, 3-nitroaniline, 4-nitroaniline, p-trifluoromethylaniline, p-hydroxyaniline, n-hexylamine, furfurylamine, naphthylamine, 2-thiophene methylamine, and benzylamine.

[0082] According to a preferred embodiment of the present invention, the furan compound is selected from at least one of 2-methylfuran, 2,5-dimethylfuran, and furan.

[0083] In this invention, there is no particular limitation on the type of liquid phase diluent, as long as it does not react with the substrate. Conventional liquid phase diluents in the art can be used in this invention. According to a preferred embodiment of this invention, the liquid phase diluent is selected from at least one of anhydrous methanol, anhydrous ethanol, propanol, isopropanol, n-butanol, toluene, cyclohexane, n-hexane, dichloromethane, tetrahydrofuran, acetone, and methyl isobutyl ketone.

[0084] In this invention, the ratio of 2,5-hexanedione and / or furan compounds to catalyst can be selected over a wide range. According to a preferred embodiment of this invention, the mass ratio of 2,5-hexanedione and / or furan compounds to catalyst is 1-100:1, preferably 2-30:1.

[0085] In this invention, the ratio of 2,5-hexanedione and / or furan compounds to amine compounds can be selected over a wide range. According to a preferred embodiment of this invention, the mass ratio of 2,5-hexanedione and / or furan compounds to amine compounds is 0.2-100:1, preferably 0.5-50:1.

[0086] In this invention, the ratio of liquid phase diluent to 2,5-hexanedione and / or furan compounds can be selected over a wide range. According to a preferred embodiment of this invention, the mass ratio of liquid phase diluent to 2,5-hexanedione and / or furan compounds is 0.1-200:1, preferably 5-50:1.

[0087] In this invention, the contact conditions between 2,5-hexanedione and / or furan compounds and amine compounds can be selected over a wide range. According to a preferred embodiment of this invention, the contact conditions include: a temperature of 100-220°C, preferably 120-200°C; and / or a time of 1-24h, preferably 4-20h.

[0088] In this invention, the N-substituted pyrrole compounds of the reaction product were qualitatively and quantitatively analyzed by gas chromatography-mass spectrometry (GC-MS), and the conversion rate of soluble carbohydrates in the product was analyzed by high-performance liquid chromatography (HPLC). The GC-MS system was an Agilent 7890A from Agilent Technologies, USA, with an HP-5 nonpolar capillary column (30m, 0.53mm). The gas chromatograph was an Agilent 7890B, with a flame ionization detector (FID) and an SE-54 capillary column (30m, 0.53mm). HPLC analysis was performed using an Agilent 1200 system with a SHODEX SC1011 sugar column (8×300mm).

[0089] The acid content and type of metal-organic framework materials were determined using the pyridine adsorption infrared method (Nicolet Model 710 spectrometer). The specific operational steps are as follows: a) Sample pretreatment: The sample (approximately 30 mg) was compressed into thin discs with a diameter of 13 mm and placed in the infrared sample cell. The sample was then pretreated in a vacuum chamber at 150 °C for 1 hour. After the sample cell cooled to room temperature, the infrared data of the sample was scanned as background. b) Pyridine adsorption: Pyridine vapor was introduced into the in-situ under room temperature and vacuum conditions until adsorption reached equilibrium, with an adsorption time of 1 hour. c) Pyridine desorption: After adsorption, a vacuum was applied at 100 °C until the internal pressure no longer changed, with a desorption time of 40 minutes. The infrared absorption spectra were then scanned and recorded. The difference spectrum before and after pyridine adsorption is the obtained pyridine adsorption-infrared absorption spectrum. The acid content of the sample was semi-quantitatively calculated based on the spectrum.

[0090]

[0091]

[0092] Where r and w are the diameter (cm) and mass (g) of the catalyst disc, respectively, and A is the integral value of absorbance at a specified wavenumber peak based on the scanned pyridine adsorption-infrared absorption spectrum. IMEC is the integral molar extinction coefficient, with IMECL being 2.22 and IMECB being 1.67.

[0093] The XRD measurement method was as follows: the phase composition of the sample was analyzed using a Rigaku Ultima IV X-ray powder diffractometer (Japan), with a CuKα ray source. Nickel filter, 2θ scanning range 3°-75°, operating voltage 35KV, current 25mA, scanning rate 10° / min.

[0094] In this invention, the contact angle measuring instrument is a DSA100 from KRUSS GmbH, Germany. The angle θ between the tangent line drawn from the gas-liquid-solid interface at the point of contact between the three phases (gas, liquid, and solid) and the solid-liquid boundary line passing through this contact point is the contact angle of the liquid on the solid surface. When the gas is air, the solid is a metal-organic framework (MOF) material, and the liquid is water, the measured contact angle is the contact angle between the MOF material and water. A larger contact angle indicates better relative hydrophobicity of the MOF material.

[0095] In this invention, scanning electron microscope (SEM) images of the samples were taken using a Hitachi S-4800II scanning electron microscope. The instrument's accelerating voltage was 15 kV, and all samples underwent chrome plating before analysis.

[0096] In this invention, the instruments and methods for testing the average pore size, specific surface area, and pore volume of the samples are as follows: Physical adsorption using nitrogen gas was performed at -196℃ using a 3H-2000PM2 physical adsorption instrument to analyze the pore structure characteristics of each adsorbent material sample. The initial degassing conditions were: degassing at 150℃ for 6 hours. After obtaining the adsorption isotherm of nitrogen on the sample, the specific surface area was calculated using the BET (Brunauer-Emmett-Teller) method, and the pore volume and pore size distribution were calculated using the BJH (Barrett-Joyner-Halenda) method.

[0097] Conversion rate % of 2,5-hexanedione and / or furan compounds = (molar amount of 2,5-hexanedione and / or furan compounds participating in the reaction) / (molar amount of 2,5-hexanedione and / or furan compounds as reaction substrates) × 100%.

[0098] Yield % of N-substituted pyrrole compound = (molar amount of N-substituted pyrrole generated in the reaction) / (molar amount of reaction substrate 2,5-hexanedione and / or furan compound) × 100%.

[0099] The selectivity % of the product N-substituted pyrrole = (molar amount of N-substituted pyrrole produced in the reaction) / (molar amount of 2,5-hexanedione and / or furan compounds in the reaction) × 100%.

[0100] To facilitate understanding of the present invention, the following embodiments are provided. However, these embodiments are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0101] Example 1

[0102] S1. Weigh 3g of trimesic acid and add it to a mixture of 70mL anhydrous ethanol and 40mL LDM, stirring thoroughly for 20min. Weigh 6g of copper nitrate trihydrate and dissolve it in 70mL H2O. Mix the two solutions together, stir thoroughly, and place the mixture in a reaction vessel. Crystallize at 85℃ for 20h. After crystallization, cool to room temperature, centrifuge to remove the mother liquor, and wash several times with ethanol. Drying is carried out in two stages: the first stage is at 75℃ for 4h, and the second stage is at 150℃ for 10h. Then, vacuum dry at 100℃ for 10h to obtain Cu-BTC.

[0103] S2. Weigh 0.6 g of benzimidazole (BzIm) and add it to 80 mL of methanol, stirring thoroughly to obtain a methanol solution. Weigh 1.2 g of Cu-BTC prepared in step S1 and add it to the methanol solution, controlling the rotation speed at 400-600 r / min. Then, add 0.8 g of triethylamine dropwise, stirring thoroughly for 6 h. Place the solution in a reaction vessel and crystallize at 80 °C for 16 h. After crystallization, cool to room temperature, centrifuge to remove the mother liquor, and wash with methanol. Drying is carried out in two stages. The first stage is at 75 °C for 4 h. After drying, soak it in dichloromethane for 48 h, changing the solution every 24 h. The second stage of drying is at 150 °C for 10 h. Then, vacuum dry at 100 °C for 10 h to obtain hydrophobic Cu-BTC-BzIm.

[0104] SEM images of samples Cu-BTC and Cu-BTC-BzIm are shown below. Figure 1 As shown, the SEM image of Cu-BTC is as follows: Figure 1 As shown in (a), the crystals are regular octahedrons with smooth surfaces, and the crystal size is 12-18 μm. The SEM image of Cu-BTC-BzIm is shown below. Figure 1 As shown in (b), the crystal form of Cu-BTC-BzIm did not change significantly, but there were clusters of flaky protrusions on the surface, thus forming a wrinkled outer surface.

[0105] pyridine desorption infrared spectroscopy of samples Cu-BTC and Cu-BTC-BzIm as shown in Figure 1 Figure 2 As shown, by Figure 2 The total acidity of Cu-BTC-BzIm was calculated to be 178.6 μmol·g. -1 The total acidity of Cu-BTC is 50.3 μmol·g. -1 .

[0106] Cu-BTC material is hydrophilic because its ligands are carboxylic acids. Figure 3 As shown in the figure. After modification with imidazole ligands containing benzene rings, the Cu-BTC-BzIm material exhibits certain hydrophobicity compared to Cu-BTC. The contact angle test results are shown in the figure. Figure 4 As shown, the contact angle between Cu-BTC-BzIm and water is 78-81°.

[0107] The nitrogen adsorption-desorption curves of Cu-BTC and Cu-BTC-BzIm are as follows: Figure 5 As shown; among them, the specific surface area of ​​Cu-BTC is 1572.8 m². 2 ·g -1 External specific surface area: 43.1 m² 2 ·g -1 Total pore volume: 0.72 cm³ 3 ·g -1 0.62cm 3 ·g -1 ;

[0108] Cu-BTC-BzIm has a specific surface area of ​​1316.1 m². 2 ·g -1 External specific surface area: 78.8 m² 2 ·g -1 Total pore volume: 0.77 cm³ 3 ·g -1 0.38cm 3 ·g -1 Compared to Cu-BTC, Cu-BTC-BzIm material has a lower total specific surface area, but an increased external specific surface area and a smaller micropore volume, thus increasing the mesopore / macropore volume.

[0109] Example 2

[0110] S1. Weigh 3g of trimesic acid and add it to a mixture of 70mL anhydrous ethanol and 40mL LDM, stirring thoroughly for 20min. Weigh 6g of copper nitrate trihydrate and dissolve it in 70mL H2O. Mix the two solutions together, stir thoroughly, and place the mixture in a reaction vessel. Crystallize at 85℃ for 20h. After crystallization, cool to room temperature, centrifuge to remove the mother liquor, and wash several times with ethanol. Drying is carried out in two stages: the first stage is at 75℃ for 4h, and the second stage is at 150℃ for 10h. Then, vacuum dry at 100℃ for 10h to obtain Cu-BTC.

[0111] S2. Weigh 1.2 g of benzimidazole and add it to 80 mL of methanol, stirring thoroughly to obtain a methanol solution. Weigh the Cu-BTC prepared in step S1 and add it to the methanol solution, controlling the rotation speed at 400-600 r / min. Then, add 0.8 g of triethylamine dropwise, stirring thoroughly for 6 h. The solution is then placed in a reaction vessel and crystallized at 80 °C for 16 h. After crystallization, cool to room temperature, centrifuge to remove the mother liquor, and wash with methanol. Drying is carried out in two stages. The first stage is at 75 °C for 4 h. After drying, immerse it in dichloromethane for 48 h, changing the solution every 24 h. The second stage is at 150 °C for 10 h. Finally, vacuum dry at 100 °C for 10 h to obtain hydrophobic Cu-BTC-BzIm-2.

[0112] SEM image of Cu-BTC-BzIm-2 is shown below. Figure 6 As shown, the crystal surface has clusters of lamellar protrusions, forming a wrinkled outer surface, and in contrast... Figure 1 (b) The clustered, sheet-like protrusions are more densely packed.

[0113] The total acidity of Cu-BTC-BzIm-2 is 159.3 μmol·g. -1 It has a hydrophobic angle of 90° and a specific surface area of ​​1200.7 m². 2 ·g -1 External specific surface area: 61.5 m² 2 ·g -1 Total pore volume: 0.68 cm³ 3 ·g -1 0.35cm 3 ·g -1 .

[0114] Example 3

[0115] The method of Example 1 was followed, except that in step S2, 0.4g of benzimidazole was used instead of 0.6g of benzimidazole, and the other conditions were the same as in Example 1, to obtain Cu-BTC-BzIm-3.

[0116] The SEM image of Cu-BTC-BzIm-3 is similar to the Cu-BTC-BzIm morphology image of Example 1.

[0117] The total acidity of Cu-BTC-BzIm-3 is 175.5 μmol·g. -1 It has a hydrophobic angle of approximately 72° and a specific surface area of ​​1408.9 m². 2 ·g -1 External specific surface area: 55.2 m² 2 ·g -1 Total pore volume: 0.7 cm³ 3 ·g -1 0.49cm 3 ·g -1 .

[0118] Example 4

[0119] The method of Example 1 was followed, except that in step S2, the amount of triethylamine used was 2.4 g; the other conditions were the same as in Example 1, and Cu-BTC-BzIm-4 was obtained.

[0120] The SEM image of Cu-BTC-BzIm-4 is similar to the Cu-BTC-BzIm morphology image of Example 1.

[0121] The total acidity of Cu-BTC-BzIm-4 is 147.1 μmol·g. -1 It has a hydrophobic angle of approximately 65° and a specific surface area of ​​1219.5 m². 2 ·g -1 External specific surface area: 50.7 m² 2 ·g -1 Total pore volume: 0.61 cm³ 3 ·g -1 0.37cm 3 ·g -1 .

[0122] Example 5

[0123] The method of Example 1 was followed, except that in step S2, 80 mL of toluene was used instead of 80 mL of methanol, and the other conditions were the same as in Example 1, to obtain Cu-BTC-BzIm-5.

[0124] The SEM image of Cu-BTC-BzIm-5 is similar to the Cu-BTC-BzIm morphology image of Example 1.

[0125] The total acidity of Cu-BTC-BzIm-5 is 166.2 μmol·g. -1 It has a hydrophobic angle of approximately 95° and a specific surface area of ​​1299.3 m². 2 ·g -1External specific surface area: 89.2 m² 2 ·g -1 Total pore volume: 0.75 cm³ 3 ·g -1 0.32cm 3 ·g -1 .

[0126] Example 6

[0127] The method of Example 1 was followed, except that in step S2, 80 mL of ethanol was used instead of 80 mL of methanol, and the other conditions were the same as in Example 1, to obtain Cu-BTC-BzIm-6.

[0128] The SEM image of Cu-BTC-BzIm-6 is similar to the Cu-BTC-BzIm morphology image of Example 1.

[0129] The total acidity of Cu-BTC-BzIm-6 is 177.9 μmol·g. -1 It has a hydrophobic angle of approximately 82° and a specific surface area of ​​1357.8 m². 2 ·g -1 External specific surface area: 80.7 m² 2 ·g -1 Total pore volume: 0.78 cm³ 3 ·g -1 0.41cm 3 ·g -1 .

[0130] Example 7

[0131] The method of Example 1 was followed, except that in step S2, 0.6 g of 2-methylbenzimidazole was used instead of benzimidazole, and the other conditions were the same as in Example 1, to obtain Cu-BTC-BzIm-7.

[0132] The SEM image of Cu-BTC-BzIm-7 is similar to the Cu-BTC-BzIm morphology image of Example 1.

[0133] The total acidity of Cu-BTC-BzIm-7 is 170.4 μmol·g. -1 It has a hydrophobic angle of approximately 86° and a specific surface area of ​​1309.2 m². 2 ·g -1 External specific surface area: 81.6 m² 2 ·g -1 Total pore volume: 0.76 cm³ 3 ·g -1 0.39cm 3 ·g -1 .

[0134] Example 8

[0135] The method of Example 1 was followed, except that in step S2, 0.6 g of 5,6-dimethylbenzimidazole was used instead of benzimidazole, and the other conditions were the same as in Example 1, to obtain Cu-BTC-BzIm-8.

[0136] The SEM image of Cu-BTC-BzIm-8 is similar to the Cu-BTC-BzIm morphology image of Example 1.

[0137] The total acidity of Cu-BTC-BzIm-8 is 165.1 μmol·g. -1 It has a hydrophobic angle of approximately 91° and a specific surface area of ​​1281.1 m². 2 ·g -1 External specific surface area: 82.3 m² 2 ·g -1 Total pore volume: 0.69 cm³ 3 ·g -1 0.34cm 3 ·g -1 .

[0138] Example 9

[0139] The method of Example 1 is followed, except that in step S1, 2.4g of terephthalic acid is used instead of 3g of trimesic acid, and the other conditions are the same as in Example 1, to obtain Cu-BDC-BzIm.

[0140] The crystal exhibits a multifaceted cubic crystal form.

[0141] The total acidity of Cu-BDC-BzIm is 125.8 μmol·g. -1 It has a hydrophobic angle of approximately 70° and a specific surface area of ​​1003.5 m². 2 ·g -1 External specific surface area: 35.4 m² 2 ·g -1 Total pore volume: 0.59 cm³ 3 ·g -1 0.3cm 3 ·g -1 .

[0142] Example 10

[0143] S1. Weigh 2.4g of terephthalic acid and add it to a mixture of 70mL anhydrous ethanol and 40mL LDM, stirring thoroughly for 20min. Weigh 7.38g of zinc nitrate hexahydrate and dissolve it in 70mL H2O. Mix the two solutions together, stir thoroughly, and place the mixture in a reaction vessel for crystallization at 85℃ for 20h. After crystallization, cool to room temperature, centrifuge to remove the mother liquor, and wash several times with ethanol. Drying is carried out in two stages: the first stage is at 75℃ for 4h, and the second stage is at 150℃ for 10h. Then, vacuum dry at 100℃ for 10h to obtain Zn-BDC.

[0144] S2. Weigh 0.6 g of benzimidazole (BzIm) and add it to 80 mL of methanol, stirring thoroughly to obtain a methanol solution. Weigh 1.2 g of Zn-BDC prepared in step S1 and add it to the methanol solution, controlling the rotation speed at 400-600 r / min. Then, add 0.8 g of triethylamine dropwise, stirring thoroughly for 6 h. Place the solution in a reaction vessel and crystallize at 80 °C for 16 h. After crystallization, cool to room temperature, centrifuge to remove the mother liquor, and wash with methanol. Drying is carried out in two stages. The first stage is at 75 °C for 4 h. After drying, soak it in dichloromethane for 48 h, changing the solution every 24 h. The second stage of drying is at 150 °C for 10 h. Then, vacuum dry at 100 °C for 10 h to obtain hydrophobic Zn-BDC-BzIm.

[0145] The crystal exhibits a multifaceted cubic crystal form.

[0146] The total acidity of Zn-BDC-BzIm is 143.2 μmol·g. -1 It has a hydrophobic angle of approximately 79° and a specific surface area of ​​1689.4 m². 2 ·g -1 External specific surface area: 85.3 m² 2 ·g -1 Total pore volume: 0.89 cm³ 3 ·g -1 0.52cm 3 ·g -1 .

[0147] Example 11

[0148] (I) Weigh 3g of trimesic acid (BTC) and add it to a mixture of 70mL anhydrous ethanol and 40mL LDM, stirring thoroughly for 20min. Weigh 6.0g of copper nitrate trihydrate and dissolve it in 70mL H2O. Mix the two solutions together, stir thoroughly, and place the mixture in a reaction vessel for crystallization at 85℃ for 20h. After crystallization, cool to room temperature, centrifuge to remove the mother liquor, and wash with ethanol. Drying is carried out in two stages: the first stage is at 75℃ for 4h, and the second stage is at 130℃ for 10h. After drying, Cu-BTC is obtained.

[0149] (II) Weigh 0.15g of ferrous sulfate and dissolve it in 20mL of water. Add 0.1g of iron powder, stir for 20min, then add 100mL of ethanol and stir thoroughly for 20min to obtain an iron-containing solution. Weigh 2.0g of Cu-BTC prepared in step S1 and add it to the iron-containing solution. Then place it in a water bath at 80℃ and react for 6h. Afterward, centrifuge to remove the mother liquor, wash with ethanol and water alternately, and dry to obtain Fe-Cu-BTC.

[0150] Infrared spectra of pyridine desorption from Cu-BTC and Fe-Cu-BTC are shown below. Figure 7 As shown, by Figure 7 It can be seen that Fe-Cu-BTC contains only Lewis acid, with an acid content of 209.3 μmol·g. -1 .

[0151] Depend on Figure 8 It can be seen that the characteristic peak positions of the Fe-Cu-BTC and Cu-BTC samples are consistent, indicating that they have the same crystal form.

[0152] Example 12

[0153] (I) Weigh 3g of trimesic acid (BTC) and add it to a mixture of 70mL anhydrous ethanol and 40mL LDM, stirring thoroughly for 20min. Weigh 6g of copper nitrate trihydrate and dissolve it in 70mL H2O. Mix the two solutions together, stir thoroughly, and place the mixture in a reaction vessel for crystallization at 85℃ for 20h. After crystallization, cool to room temperature, centrifuge to remove the mother liquor, and wash with ethanol. Drying is carried out in two stages: the first stage is at 75℃ for 4h, and the second stage is at 130℃ for 10h. After drying, Cu-BTC is obtained.

[0154] (II) Weigh 0.25 g of silver nitrate and dissolve it in 20 mL of water. Stir for 20 min, then add 80 mL of ethanol and stir thoroughly for 20 min to obtain a silver-containing solution. Weigh 2.0 g of Cu-BTC prepared in step S1 and add it to the silver-containing solution. Then place it in a water bath at 85 °C and react for 6 h. Afterward, centrifuge to remove the mother liquor, wash with ethanol and water alternately, and dry to obtain Ag-Cu-BTC.

[0155] Example 13

[0156] S1. Weigh 2.5g of zirconium tetrachloride and 1.8g of terephthalic acid and dissolve them in 80mL of N,N-dimethylformamide to obtain solution A. Then, transfer the above system to a crystallization vessel and crystallize at 120℃ for 20h. After crystallization, cool to room temperature, centrifuge to remove the mother liquor, and wash several times with ethanol. Drying is carried out in two stages: the first stage is at 75℃ for 4h, and the second stage is at 160℃ for 12h. After vacuum drying, UiO-66 is obtained.

[0157] S2. Weigh 1.0 g of the prepared UiO-66 and place it in 100 mL of toluene. Add chlorosilane to make the molar concentration 1.5 mM. Stir at 130 °C for 10 h under N2 atmosphere. Then centrifuge the suspension and wash it three times with toluene. After that, dry it under vacuum at 160 °C for 20 h to obtain hydrophobic UiO-66.

[0158] Example 14

[0159] The method of Example 11 was followed, except that in step (II), 0.2 g of ferrous chloride was added instead of 0.15 g of ferrous sulfate, and the other conditions were the same as in Example 1; Fe-Cu-BTC-2 was obtained.

[0160] pyridine desorption infrared spectroscopy revealed that Fe-Cu-BTC-2 contained only L-acid, with an acid content of 217.3 μmol·g. -1 .

[0161] Examples 15-29

[0162] Using 2,5-hexanedione and aniline as substrates and methanol as the reaction solvent, 0.2 g of the catalyst from Examples 1-14, 2.0 g of 2,5-hexanedione, 1.2 g of aniline, and 10 g of methanol were added to a high-pressure reactor equipped with a stirrer. Nitrogen gas at 1 MPa was introduced to prevent boiling of the organic solvent. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 150 °C for 6 h. The conversion rate of 2,5-hexanedione and the yield of the target product 2,5-dimethyl-1-phenylpyrrole were analyzed and are shown in Table 1.

[0163] Table 1 Catalytic evaluation results of Examples 15-29

[0164]

[0165] Example 30

[0166] The method of Example 15 is the same, except that the amount of catalyst used is 0.1g, and the other conditions are the same as in Example 15.

[0167] Analysis of the reaction solution showed that the conversion rate of 2,5-hexanedione was 97.1%; the yield of the target product 2,5-dimethyl-1-phenylpyrrole was 96.8%.

[0168] Example 31

[0169] The method of Example 15 is the same, except that the amount of catalyst used is 0.5g, and the other conditions are the same as in Example 15.

[0170] Analysis of the reaction solution showed that the conversion rate of 2,5-hexanedione was 98.9%; the yield of the target product 2,5-dimethyl-1-phenylpyrrole was 98.5%.

[0171] Example 32

[0172] The method of Example 15 is the same as that of Example 15, except that the reaction is carried out at 180°C for 6 hours.

[0173] Analysis of the reaction solution showed that the conversion rate of 2,5-hexanedione was 99.7%; the yield of the target product 2,5-dimethyl-1-benzylpyrrole was 97.2%.

[0174] Example 33

[0175] The method of Example 15 is the same as that of Example 15, except that the reaction is carried out at 120°C for 6 hours.

[0176] Analysis of the reaction solution showed that the conversion rate of 2,5-hexanedione was 96.8%; the yield of the target product 2,5-dimethyl-1-phenylpyrrole was 98.7%.

[0177] Example 34

[0178] The method of Example 15 is the same as that of Example 15, except that the reaction is carried out at 150°C for 12 hours.

[0179] Analysis of the reaction solution showed that the conversion rate of 2,5-hexanedione was 99.8%; the yield of the target product 2,5-dimethyl-1-phenylpyrrole was 96.1%.

[0180] Example 35

[0181] The method of Example 15 is the same, except that the amount of aniline used is 0.6g, and the other conditions are the same as in Example 15.

[0182] Analysis of the reaction solution showed that the conversion rate of 2,5-hexanedione was 93.2%; the yield of the target product 2,5-dimethyl-1-phenylpyrrole was 92.8%.

[0183] Example 36

[0184] The method of Example 15 is the same as that of Example 15, except that tetrahydrofuran is used instead of methanol.

[0185] Analysis of the reaction solution showed that the conversion rate of 2,5-hexanedione was 97.6%; the yield of the target product 2,5-dimethyl-1-phenylpyrrole was 96.9%.

[0186] Example 37

[0187] The method of Example 15 is the same as that of Example 15, except that toluene is used instead of methanol.

[0188] Analysis of the reaction solution showed that the conversion rate of 2,5-hexanedione was 98.2%; the yield of the target product 2,5-dimethyl-1-phenylpyrrole was 97.8%.

[0189] Example 38

[0190] The method of Example 15 is the same, except that the amine compound is m-toluidine, and the other conditions are the same as in Example 15.

[0191] Analysis of the reaction solution showed that the conversion rate of 2,5-hexanedione was 98.1%; the yield of the target product 2,5-dimethyl-1-m-phenylmethyl-1-H-pyrrole was 80.3%.

[0192] Example 39

[0193] The method of Example 15 is the same, except that the amine compound is p-methoxyaniline, and the other conditions are the same as in Example 15.

[0194] Analysis of the reaction solution showed that the conversion rate of 2,5-hexanedione was 97.2%; the yield of the target product 1-(4-methoxyphenyl)-2,5-dimethyl-1H-pyrrole was 78.5%.

[0195] Example 40

[0196] The method of Example 15 is the same, except that the amine compound is m-chloroaniline, and the other conditions are the same as in Example 15.

[0197] Analysis of the reaction solution showed that the conversion rate of 2,5-hexanedione was 99.2%; the yield of the target product 1-(3-chlorophenyl)-2,5-dimethyl-1H-pyrrole was 93.4%.

[0198] Example 41

[0199] The method of Example 15 was followed, except that an equal mass of 2,5-dimethylfuran was used instead of 2,5-hexanedione, while the other conditions remained the same as in Example 15. Analysis of the reaction solution revealed a 2,5-dimethylfuran conversion of 90.7% and a yield of 85.1% for the target product, 2,5-dimethyl-1-phenylpyrrole.

[0200] Example 42

[0201] The method of Example 15 was followed, except that an equal mass of 2-methylfuran was used instead of 2,5-hexanedione, while the other conditions remained the same as in Example 15. Analysis of the reaction solution revealed a 2-methylfuran conversion of 89.3% and a yield of 82.3% for the target product, 2-dimethyl-1-phenylpyrrole.

[0202] Comparative Example 1

[0203] Using 2,5-hexanedione and aniline as substrates and methanol as the reaction solvent, 0.2 g of HY(37), 2.0 g of 2,5-hexanedione, and 1.2 g of aniline were added to a high-pressure reactor equipped with a stirrer. Nitrogen gas at 1 MPa was introduced to prevent boiling of the organic solvent. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 150 °C for 6 h. Analysis of the reaction solution showed that the conversion rate of 2,5-hexanedione was 88.5%, and the yield of the target product, 2,5-dimethyl-1-phenylpyrrole, was 72.7%.

[0204] Comparative Example 2

[0205] Using 2,5-hexanedione and aniline as substrates and methanol as the reaction solvent, 0.2 g of H-Beta(100), 2.0 g of 2,5-hexanedione, and 1.2 g of aniline were added to a high-pressure reactor equipped with a stirrer. Nitrogen gas was introduced at 1 MPa to prevent boiling of the organic solvent. The temperature was raised to the preset temperature using a programmed heating mantle, and the mixture was stirred magnetically. The reaction was carried out at 150 °C for 6 h. Analysis of the reaction solution showed that the conversion rate of 2,5-hexanedione was 72.5%, and the yield of the target product, 2,5-dimethyl-1-phenylpyrrole, was 66.9%.

[0206] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing an N-substituted pyrrole compound, characterized in that, The method includes: In the presence of a liquid diluent and a catalyst, 2,5-hexanedione and / or furan compounds are contacted with amine compounds; the furan compounds are selected from at least one of 2-methylfuran, 2,5-dimethylfuran, and furan; the amine compounds are selected from at least one of aniline, m-chloroaniline, p-methoxyaniline, 3-methoxyaniline, m-toluidine, and o-toluidine. The catalyst contains a metal-organic framework material; The metal-organic framework material is a dual-ligand MOF material, comprising: Metal center; and A carboxylic acid organic ligand and a polyazole organic ligand coordinated to at least two binding sites of the metal center to form a partially crystalline network structure with multiple internal pores; the metal of the metal center is Zn or Cu; the carboxylic acid organic ligand is selected from at least one of trimellitic acid, terephthalic acid, phthalic acid, biphenyl-3,4,5-tricarboxylic acid, 1,4-naphthalenedicarboxylic acid, biphenyl dicarboxylic acid, and 3,3,5,5-biphenyltetracarboxylic acid; the polyazole organic ligand is selected from at least one of benzimidazole, 2-methylbenzimidazole, 5,6-dimethylbenzimidazole, 2-(2-hydroxybenzyl)benzimidazole, and 2-aminobenzimidazole; the contact angle between the dual-ligand MOF material and water is 40-100°; and / or The metal-organic framework material is a copper-iron bimetallic MOF material, including: Bimetallic centers formed by Fe and Cu; and Organic ligands that hybridize with bimetallic centers through coordination bonds to form a three-dimensional network structure crystal; The organic ligands of the copper-iron bimetallic MOFs material are selected from at least one of pyromellitic acid, terephthalic acid, phthalic acid, biphenyl-3,4,5-tricarboxylic acid, 1,4-naphthalenedicarboxylic acid, biphenyl dicarboxylic acid, and 1,3,5-tris(4-carboxyphenyl)benzene. The copper-iron bimetallic MOFs material contains only L acid, and the amount of L acid is 100-600 µmol•g. -1 .

2. The preparation method according to claim 1, wherein, The dual-ligand MOF material crystals have a wrinkled outer surface; and / or The contact angle between the described dual-ligand MOF material and water is 40-120°.

3. The preparation method according to claim 1, wherein, The dual-ligand MOFs material has clusters of lamellar protrusions on its crystal surface, forming a wrinkled outer surface.

4. The preparation method according to claim 1, wherein, The total acidity of the dual-ligand MOFs material is 30-500 µmol•g. -1 ; and / or The total specific surface area of ​​the dual-ligand MOFs material is 900-1800 m². 2 •g -1 ; and / or The total pore volume of the described dual-ligand MOFs material is 0.4-1.0 cm³. 3 •g -1 .

5. The preparation method according to claim 1, wherein, The total acidity of the dual-ligand MOFs material is 40-400 µmol•g. -1 ; and / or The total specific surface area of ​​the dual-ligand MOFs material is 40-200 m². 2 •g -1 ; and / or The total pore volume of the described dual-ligand MOFs material is 0.2-0.9 cm³. 3 •g -1 .

6. The preparation method according to claim 1, wherein, The preparation method of the dual-ligand MOF material includes the following steps: S1. Dissolve soluble metal salts and carboxylic acid organic ligands in solvent I, crystallize, separate, and first dry to obtain MOF materials formed by metal and organic ligand I; S2. Contact the MOF material from step S1 with a solution containing polyazole organic ligands and alkaline substances; separate, wash, and perform a second drying to obtain the metal-organic framework material.

7. The preparation method according to claim 6, wherein, In step S1, the molar ratio of the soluble metal salt to the carboxylic acid organic ligand is 1:0.2-5; and / or In step S1, the ratio of solvent I to soluble metal salt is 5-100 mL solvent I / 1.0 g soluble metal salt; and / or In step S2, the molar ratio of MOF materials to polyazole organic ligands is 1:(0.01-5); and / or In step S2, the molar ratio of MOF materials to alkaline substances is 1:(0.01-3); and / or In step S2, the solution containing polyazole organic ligands and an alkaline substance uses solvent II, which is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, methanol, ethanol, acetone, dichloromethane, toluene, and ethylbenzene; and / or In step S2, the alkaline substance is selected from at least one of triethylamine, trimethylamine, diisopropylethylamine, diethylamine, n-propylamine, n-butylamine, di-n-butylamine, ammonia, and aniline.

8. The preparation method according to claim 7, wherein, The mass ratio of MOF material to solvent II is 1:(2-200).

9. The preparation method according to claim 7, wherein, In step S1, the crystallization conditions include: a crystallization temperature of 30-200℃; and / or a crystallization time of 3-44h; and / or In step S1, the first drying conditions include: a drying temperature of 70-200℃; and / or a drying time of 2-48 hours; and / or In step S2, the contact conditions include: a contact temperature of 30-180℃; and / or a contact time of 3-30 hours; and / or In step S2, the second drying conditions include: a drying temperature of 70-200℃; and / or a drying time of 2-48h.

10. The preparation method according to claim 1, wherein, The L-acid content of the copper-iron bimetallic MOFs material is 150-400 µmol•g. -1 ; and / or The organic ligands of the copper-iron bimetallic MOFs material are at least one of pyromellitic acid and terephthalic acid.

11. The preparation method according to claim 1, wherein, The preparation method of the copper-iron bimetallic MOFs material includes: (I) Dissolve organic ligands and Cu salts in a solvent, crystallize, separate, and first dry to obtain Cu-based MOFs materials formed by Cu and organic ligands; (II) Contact the Cu-based MOFs material from step (I) with an aqueous alcohol mixture containing elemental Fe and Fe salt; separate and perform a second drying to obtain the copper-iron bimetallic MOFs material.

12. The preparation method according to claim 11, wherein, In step (I), the crystallization conditions include: a crystallization temperature of 30-150℃; and / or a crystallization time of 3-24h; and / or In step (I), the first drying conditions include: a drying temperature of 70-200℃; and / or a drying time of 2-48h; and / or In step (II), the contact conditions include: a contact temperature of 30-150°C; and / or a contact time of 3-24 hours.

13. The preparation method according to claim 11, wherein, In step (I), the solvent to Cu salt ratio is 5-100 mL solvent / 1.0 g Cu salt; and / or In step (II), the molar ratio of elemental Fe to soluble Fe salt is 1:0.1-10; In step (II), the ratio of Fe salt used is 5-200 mL solvent / 1.0 g.

14. The preparation method according to claim 1 or 2, wherein, The liquid phase diluent is selected from at least one of anhydrous methanol, anhydrous ethanol, propanol, isopropanol, n-butanol, toluene, cyclohexane, n-hexane, dichloromethane, tetrahydrofuran, acetone, and methyl isobutyl ketone.

15. The preparation method according to claim 1 or 2, wherein, The mass ratio of 2,5-hexanedione and / or furans to the catalyst is 1-100:1; and / or The mass ratio of 2,5-hexanedione and / or furans to amines is 0.2-100:1; and / or The mass ratio of the liquid phase diluent to 2,5-hexanedione and / or furan compounds is 0.1-200:1; and / or Contact conditions include: temperature 100-220℃; And / or the time is 1-24h.

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