CN107903399B

CN107903399B - Preparation method of MOF material for catalyzing amidation reaction

Info

Publication number: CN107903399B
Application number: CN201710969134.8A
Authority: CN
Inventors: 桑欣欣; 王大伟; 倪才华; 石刚
Original assignee: Jiangnan University
Current assignee: Jiangnan University
Priority date: 2017-10-18
Filing date: 2017-10-18
Publication date: 2020-11-24
Anticipated expiration: 2037-10-18
Also published as: CN107903399A

Abstract

The invention provides a preparation method of a heterogeneous Zr-MOF catalyst and application of the heterogeneous Zr-MOF catalyst in catalytic amidation reaction, and belongs to the field of catalyst synthesis and catalysis. The preparation method comprises the following steps of carrying out solvothermal reaction on aromatic carboxylic acid serving as an organic ligand and zirconium oxychloride in a solution of N, N-dimethylformamide and acetic acid to obtain a metal-organic framework material, wherein the Zr-MOF has a three-dimensional pore structure formed by octahedral cages and tetrahedral cages which are alternately arranged, has a carboxylic acid functional group which does not participate in coordination, has certain acidity, and can be used as a catalyst for amidation reaction. The Zr-MOF catalyst shows high activity in the aspect of catalyzing amidation reaction, is very stable in a catalytic system and convenient to recover and recycle, and the activity is not obviously reduced after 5 times of reaction.

Description

Preparation method of MOF material for catalyzing amidation reaction

Technical Field

The invention belongs to the field of synthesis and catalysis of catalysts, and particularly relates to a heterogeneous Zr-MOF catalyst and a catalytic amidation reaction.

Background

The formation reaction of amide bond is an important reaction in organic synthesis, and the amide bond is widely present in medical intermediates and biochemical substances. Conventional methods for synthesizing amides typically involve the use of active acylating agents such as acetic anhydride and acetyl chloride. Although these agents are inexpensive, their toxicity and hygroscopicity make them undesirable acylating agents. Many processes also use heterogeneous and homogeneous metal catalysts, which are generally expensive and require purification steps. Therefore, the development of a heterogeneous catalyst with high catalytic efficiency and long service life is of great significance.

The metal-organic framework Materials (MOFs) are porous crystal materials with a net structure formed by self-assembly of organic ligands and metal ions or ion clusters, and have wide application prospects in the aspects of gas adsorption and separation, heterogeneous catalysis and the like. Unsaturated coordination sites of metal ions in the MOFs material can be used as active centers of catalytic reaction, and a plurality of organic ligands with catalytic performance can be introduced to the skeleton of the MOFs material; the size of the MOFs framework pore can be adjusted between micro-pore and meso-pore, and the large specific surface area can also load highly dispersed nano metal active components, so that the MOFs material has unique structural characteristics different from other catalyst materials.

Acetic acid is used as a regulator to synthesize a series of Zr-MOF materials, the Zr-MOF materials are stable in structure and have a plurality of acid sites, and the Zr-MOF materials still show good catalytic performance after being repeatedly utilized for many times, so that the MOF catalyst is a good heterogeneous catalyst and has good application prospect in industrial catalytic amidation reaction.

Disclosure of Invention

The invention aims to provide a preparation method of a heterogeneous Zr-MOF catalyst and application of the heterogeneous Zr-MOF catalyst in catalyzing amidation reaction.

A heterogeneous Zr-MOF catalyst, characterized in that it has a large number of carboxylic acid functions (-COOH) not participating in coordination.

The preparation method of the heterogeneous Zr-MOF catalyst comprises the following steps:

mixing zirconium oxychloride octahydrate, aromatic carboxylic acid, N-dimethylformamide and acetic acid, performing ultrasonic treatment for 10 minutes to obtain a transparent solution, placing the transparent solution in a round-bottom flask, stirring and heating the mixed solution at 80-150 ℃ for 10-48 hours, naturally cooling the mixed solution to room temperature, performing centrifugal separation to obtain a white solid, washing the white solid with N, N-dimethylformamide for three times, washing and activating the white solid with methanol for three times, and performing vacuum drying (vacuum drying at 60 ℃ for 24 hours) to obtain white powder, namely the Zr-MOF material.

In the above step, the molar ratio of the zirconyl dichloride octahydrate to the aromatic carboxylic acid is preferably 1: 0.5-1: 3; the volume ratio of the N, N-dimethylformamide to the acetic acid is 1: 1-10: 1; the aromatic carboxylic acid is selected from one of terephthalic acid, trimesic acid, 1,2, 4-benzene tricarboxylic acid and 1,2,4, 5-benzene tetracarboxylic acid.

The above-synthesized Zr-MOF material can be used as a heterogeneous catalyst for amidation reaction, and after the reaction is completed, the heterogeneous catalyst can be repeatedly used without obvious reduction of catalytic activity.

According to the invention, acetic acid is used as a regulator, the MOF material with Zr as a metal site is prepared by adopting a solvothermal method, and the catalytic activity of the MOF can be regulated by changing a ligand. The catalyst has high thermal stability and chemical stability, wherein the thermal stability can reach 500 ℃, and the chemical stability shows that the structure can be kept unchanged in a high-temperature catalytic system and the catalyst can be recycled for more than 5 times. The Zr-MOF material has-COOH which is not coordinated. Therefore, the heterogeneous catalyst shows high catalytic activity in catalyzing amidation reaction.

Drawings

FIG. 1 is a thermogram of a heterogeneous Zr-MOF catalyst in an example of the invention.

FIG. 2 is an infrared image of a heterogeneous Zr-MOF catalyst in an example of the invention.

FIG. 3 is an equation for Zr-MOF catalyzed amidation reaction

FIG. 4 is an X-ray powder diffraction (XRD) pattern of the Zr-MOF catalyst after different times of reuse in the examples.

FIG. 5 is a result of repeated experiments in which the heterogeneous Zr-MOF catalyst catalyzes the amidation reaction in the examples of the present invention.

Detailed Description

The present invention will be further illustrated with reference to the following examples, but the present invention is not limited to the following examples.

The zirconium oxychloride octahydrate, the aromatic carboxylic acid, the N, N-dimethylformamide, the acetic acid, the benzylamine, the ethyl acetate and the like adopted in the implementation of the synthesis are analytically pure.

Example 1

Adding 1mmol of organic ligand trimesic acid and 3mmol of octahydrate zirconium oxychloride into a mixed solution of 30ml of N, N-dimethylformamide and 15ml of acetic acid, and carrying out ultrasonic treatment for 10 minutes to obtain a clear and transparent solution. The mixture was transferred to a single-neck flask, heated in an oil bath at 120 ℃ for 24 hours, naturally cooled to room temperature, centrifuged to remove the reaction solution, washed 3 times (100 ml/time) with each of N, N-dimethylformamide and methanol solutions, and activated in methanol for 24 hours. After centrifugation, the upper methanol solution was poured off, and the precipitate was dried in a vacuum oven at 60 ℃ for 24 hours to give a white powder.

Example 2

Adding 1mmol of organic ligand trimesic acid and 3mmol of octahydrate zirconium oxychloride into a mixed solution of 35ml of N, N-dimethylformamide and 10ml of acetic acid, and carrying out ultrasonic treatment for 10 minutes to obtain a clear and transparent solution. The mixture was transferred to a single-neck flask, heated in an oil bath at 120 ℃ for 24 hours, naturally cooled to room temperature, centrifuged to remove the reaction solution, washed 3 times (100 ml/time) with each of N, N-dimethylformamide and methanol solutions, and activated in methanol for 24 hours. After centrifugation, the upper methanol solution was poured off, and the precipitate was dried in a vacuum oven at 60 ℃ for 24 hours to give a white powder.

Example 3

Adding 1mmol of organic ligand trimesic acid and 3mmol of octahydrate zirconium oxychloride into a mixed solution of 40ml of N, N-dimethylformamide and 5ml of acetic acid, and carrying out ultrasonic treatment for 10 minutes to obtain a clear and transparent solution. The mixture was transferred to a single-neck flask, heated in an oil bath at 120 ℃ for 24 hours, naturally cooled to room temperature, centrifuged to remove the reaction solution, washed 3 times (100 ml/time) with each of N, N-dimethylformamide and methanol solutions, and activated in methanol for 24 hours. After centrifugation, the upper methanol solution was poured off, and the precipitate was dried in a vacuum oven at 60 ℃ for 24 hours to give a white powder.

Example 4

Adding 1mmol of organic ligand terephthalic acid and 1mmol of zirconium oxychloride octahydrate into a mixed solution of 30ml of N, N-dimethylformamide and 15ml of acetic acid, and carrying out ultrasonic treatment for 10 minutes to obtain a clear and transparent solution. The mixture was transferred to a single-neck flask, heated in an oil bath at 120 ℃ for 24 hours, naturally cooled to room temperature, centrifuged to remove the reaction solution, washed 3 times (100 ml/time) with each of N, N-dimethylformamide and methanol solutions, and activated in methanol for 24 hours. After centrifugation, the upper methanol solution was poured off, and the precipitate was dried in a vacuum oven at 60 ℃ for 24 hours to give a white powder.

Example 5

Adding 1mmol of

organic ligand

1,2, 4-benzene tricarboxylic acid and 1mmol of zirconium oxychloride octahydrate into a mixed solution of 30ml of N, N-dimethylformamide and 15ml of acetic acid, and carrying out ultrasonic treatment for 10 minutes to obtain a clear and transparent solution. The mixture was transferred to a single-neck flask, heated in an oil bath at 120 ℃ for 24 hours, naturally cooled to room temperature, centrifuged to remove the reaction solution, washed 3 times (100 ml/time) with each of N, N-dimethylformamide and methanol solutions, and activated in methanol for 24 hours. After centrifugation, the upper methanol solution was poured off, and the precipitate was dried in a vacuum oven at 60 ℃ for 24 hours to give a white powder.

Example 6

Adding 1mmol of

organic ligand

1,2,4, 5-benzene tetracarboxylic acid and 1mmol of zirconium oxychloride octahydrate into a mixed solution of 30ml of N, N-dimethylformamide and 15ml of acetic acid, and carrying out ultrasonic treatment for 10 minutes to obtain a clear and transparent solution. The mixture was transferred to a single-neck flask, heated in an oil bath at 120 ℃ for 24 hours, naturally cooled to room temperature, centrifuged to remove the reaction solution, washed 3 times (100 ml/time) with each of N, N-dimethylformamide and methanol solutions, and activated in methanol for 24 hours. After centrifugation, the upper methanol solution was poured off, and the precipitate was dried in a vacuum oven at 60 ℃ for 24 hours to give a white powder.

Adding the synthesized Zr-MOF catalyst and benzylamine into ethyl acetate, putting the mixed solution into a reaction kettle, and reacting for 12 hours at the temperature of 80 ℃. Wherein the amount of each reactant is 1mmol of benzylamine, 2ml of ethyl acetate and 25mg of catalyst. After the reaction is finished, centrifugal separation is carried out, and supernatant fluid and CDCl are taken₃As a solvent, use¹H NMR analysis of the product was carried out. The heterogeneous catalyst after the reaction is washed by methanol for 3 times, and is put into a vacuum oven for drying at 60 ℃ for next repeated use. The amidation reaction equation of benzylamine with ethyl acetate is as follows:

in the amidation reaction of the benzyl amine and ethyl acetate, the conversion rate of the benzyl amine is more than 99%, and the yield of the product N-acetyl benzylamine reaches 98%.

From FIG. 1, it can be seen that the heterogeneous Zr-MOF catalyst has high thermal stability, which can reach 500 ℃. It can be seen from FIG. 2 that the heterogeneous Zr-MOF catalyst contains-COOH which is not coordinated.

FIG. 3 shows the equation for heterogeneous Zr-MOF catalyzed amidation reactions.

The XRD test result in figure 4 shows that the crystal structure of the heterogeneous Zr-MOF catalyst is changed after the heterogeneous Zr-MOF catalyst is repeatedly used for 5 times, and the crystal structure of the Zr-MOF catalyst is not obviously changed after the heterogeneous Zr-MOF catalyst is repeatedly used for multiple times, which indicates that the catalyst has good thermal stability and can be repeatedly used.

As can be seen from FIG. 5, the catalyst has good reusability, and the conversion rate of the benzylamine is more than 98% after the catalyst is recycled for 5 times.

Table 1 shows the product yields of amidation reactions of different aromatic amines with ethyl acetate catalyzed by heterogeneous Zr-MOF catalysts. It can be seen that the catalyst is generally suitable for amidation reaction of aromatic amine with ethyl acetate.

TABLE 1

Claims

1. Use of a heterogeneous Zr-MOF catalyst for catalysing the amidation of an aromatic amine with ethyl acetate, wherein the method for the preparation of said heterogeneous Zr-MOF catalyst comprises the steps of: ultrasonically treating zirconium oxychloride octahydrate, aromatic carboxylic acid, N-dimethylformamide and acetic acid to obtain a transparent solution, placing the mixed solution into a round-bottom flask, stirring and heating for a period of time, naturally cooling to room temperature, carrying out centrifugal separation to obtain a white solid, washing with N, N-dimethylformamide for three times, washing with methanol for three times, activating for three times, and carrying out vacuum drying to obtain white powder, namely Zr-MOF;

the aromatic carboxylic acid is selected from one of terephthalic acid, trimesic acid, 1,2, 4-benzene tricarboxylic acid and 1,2,4, 5-benzene tetracarboxylic acid.

2. Use according to claim 1, characterized in that the molar ratio of zirconyl dichloride octahydrate to aromatic carboxylic acid is from 1:0.5 to 1: 3.

3. Use according to claim 1, characterized in that the volume ratio of N, N-dimethylformamide to acetic acid is 1:1 to 10: 1.

4. Use according to any one of claims 1 to 3, wherein the aromatic amine has the formula: