HTA-BDU-COF polymer as well as preparation method and application thereof

Abstract

The invention relates to the technical field of porous organic polymer materials, in particular to an HTA-BDU-COF polymer as well as a preparation method and application thereof. According to the HTA-BDU-COF polymer provided by the invention, when the HTA-BDU-COF polymer provided by the invention takes a structure as shown in a formula (I) as a structural repeating unit: # imgabs0 # as a catalyst and CH2Cl2 as a solvent to catalyze a Friedel-Crafts reaction of trans-nitrostyrene and indole, the yield can reach 77%. Meanwhile, after the HTA-BDU-COF polymer is subjected to six times of circular reaction, the catalytic yield of 95% or above is still kept, so that the HTA-BDU-COF polymer provided by the invention has efficient and stable catalytic performance and can be recycled for multiple times.

Description

Technical Field

[0001] The invention relates to the technical field of porous organic polymer materials, and in particular to a HTA-BDU-COF polymer and a preparation method and application thereof. Background Art

[0002] Covalent organic frameworks (COFs), as an emerging type of porous crystalline polymer in two-dimensional conjugated network materials, have size-adjustable nanopores, high specific surface area, good chemical stability, and uniformly dispersed catalytic active sites. Therefore, they have good development prospects in the field of catalysis.

[0003] Hydrogen bond donors (HBD) have the advantages of structural adjustability and good stability, and are often widely used as organic catalysts. (Thio)urea derivatives are one of the most studied organic catalysts, with a wide range of reactivity, such as Strecker reaction, Mannich reaction, Friedel-Crafts reaction and many other reactions. The double hydrogen bond donor of (thio)urea manifests its performance through NH bonds. On the one hand, it promotes the reaction and activates the substrate for catalysis; on the other hand, the polymerization between (thio)ureas will lead to its reduced activity in homogeneous systems and poor solubility, causing the hydrogen bond donor organic catalyst to self-quench, poor catalytic stability, and difficult to recycle multiple times. Summary of the invention

[0004] In order to solve the above problems, the present invention provides an HTA-BDU-COF polymer and a preparation method and application thereof. When the HTA-BDU-COF polymer is used as a catalyst to catalyze the Friedel-Crafts reaction of trans-nitrostyrene and indole, the polymer has efficient and stable catalytic performance and can be recycled multiple times.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0006] In the first aspect, the present invention provides a HTA-BDU-COF polymer, wherein the structure represented by formula (I) is used as a structural repeating unit:

[0007]

[0008] In a second aspect, the present invention provides a method for preparing the HTA-BDU-COF polymer according to the first aspect, comprising the following steps:

[0009] (1) mixing 1,4-phenylene diisocyanate with aqueous ammonia to react and prepare 1,4-diphenylurea;

[0010] (2) 2-Hydroxy-1,3,5-benzenetricarboxaldehyde, 1,4-diphenylurea and acetic acid were reacted to prepare HTA-BDU-COF polymer.

[0011] In some other embodiments, in step (1), the concentration of the aqueous ammonia is 25-30 mol·L -1 ;

[0012] The mixing ratio of the 1,4-phenylene diisocyanate to aqueous ammonia is (1.0-1.5) g: (0.3-0.5) mol.

[0013] In some other embodiments, in step (1), the reaction is carried out at 0-5°C for 1-3 hours, and then the temperature is raised to room temperature for 3-5 hours;

[0014] After the reaction is completed, filtering, washing and drying are further performed, wherein the washing is performed with water-tetrahydrofuran in a volume ratio of (1-3):1;

[0015] The drying is vacuum drying at room temperature.

[0016] In some other embodiments, in step (2), the molar ratio of 2-hydroxy-1,3,5-benzenetricarboxaldehyde, 1,4-diphenylurea and acetic acid is 1:1:1.5×10 -3 .

[0017] In some other embodiments, in step (2), the solvent consists of o-dichlorobenzene and tert-butanol, and the volume ratio of o-dichlorobenzene to tert-butanol is 1.8 to 2.2:1, preferably 2:1.

[0018] In some other embodiments, in step (2), the concentration of 2-hydroxy-1,3,5-benzenetricarboxaldehyde in the solvent is 2 to 4 mmol / L, preferably 3 mmol / L;

[0019] The concentration of the acetic acid is 5-6 mol·L -1 .

[0020] In some other embodiments, in step (2), the reaction temperature is 110-130° C., preferably 120° C.; the reaction time is 90-100 h, preferably 92 h;

[0021] After the reaction is completed, washing and drying are also carried out;

[0022] The washing is washing with dimethylformamide and tetrahydrofuran respectively;

[0023] The drying is vacuum drying.

[0024] During the research process, the inventors found that HTA-BDU-COF polymer can only be synthesized when the molar ratio of 2-hydroxy-1,3,5-benzenetricarboxaldehyde and 1,4-diphenylurea is 1:1 during the experiment, and the polymer cannot be synthesized at other molar ratios of 2-hydroxy-1,3,5-benzenetricarboxaldehyde and 1,4-diphenylurea.

[0025] In a third aspect, the present invention provides use of the HTA-BDU-COF polymer described in the first aspect in catalyzing the Friedel-Crafts reaction of trans-nitrostyrene and indole.

[0026] In a fourth aspect, the present invention provides a method for catalyzing the Friedel-Crafts reaction of trans-nitrostyrene and indole, using the HTA-BDU-COF polymer described in the first aspect as a catalyst, β-nitrostyrene and indole as raw materials, adding them to dichloromethane, and stirring at room temperature.

[0027] The beneficial effects of the present invention are:

[0028] (1) The HTA-BDU-COF polymer prepared in the present invention has the properties of high crystallinity, large porosity, and good chemical stability, and therefore has the potential to be used as a catalyst.

[0029] (2) When the HTA-BDU-COF polymer provided by the present invention is used as a catalyst and CH2Cl2 is used as a solvent to catalyze the Friedel-Crafts reaction of trans-nitrostyrene and indole, the yield can be as high as 77%.

[0030] (3) The HTA-BDU-COF polymer provided by the present invention is used as a catalyst for the Friedel-Crafts reaction of trans-nitrostyrene and indole. The catalyst is low in price, high in yield and purity, and easy to separate. No special, toxic or harmful reagents are used during the experiment, and the reaction conditions are mild. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0032] Figure 1 This is a scanning electron microscope image of HTA-BDU-COF prepared in Example 2 of the present invention;

[0033] Figure 2 Thermogravimetric diagram of HTA-BDU-COF prepared in Example 2 of the present invention;

[0034] Figure 3This is the PXRD pattern of HTA-BDU-COF prepared in Example 2 of the present invention;

[0035] Figure 4 This is the N2 adsorption diagram of HTA-BDU-COF prepared in Example 2 of the present invention;

[0036] Figure 5 This is the PXRD image of the HTA-BDU-COF prepared in Example 2 of the present invention after being used as a catalyst for 5 cycles. DETAILED DESCRIPTION

[0037] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0038] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0039] Example 1

[0040] Preparation of ligand 1,4-diphenylurea (BDU):

[0041] Aqueous ammonia solution (27.75M, 13 mL aqueous solution) was cooled to 0°C, and then 1,4-phenylene diisocyanate (1.5 g) was added in portions. The reaction mixture was stirred at 0°C for 3 h, then warmed to room temperature and stirred for another 5 h. The white solid was collected by filtration, washed with water (75 mL) and THF (75 mL), and dried in vacuo at room temperature to obtain white 1,4-diphenylurea (BDU).

[0042] The reaction process is:

[0043]

[0044] Example 2

[0045] Preparation of HTA-BDU-COF polymer:

[0046] The ligand 1,4-diphenylurea (BDU) (0.01mmol, 1.94mg) and 2-hydroxy-1,3,5-benzenetricarbaldehyde (HTA) (0.01mmol, 1.78mg) prepared in Example 1 were placed in a pressure-resistant glass tube, the reaction solvent was a mixed solution of o-dichlorobenzene and tert-butyl alcohol (2ml:1ml), 200ul of 6M acetic acid solution was added, the mixture was ultrasonically treated and mixed evenly, degassed through a freeze-pump-thaw cycle, vacuum sealed, and reacted at 120°C for 3 days. After the glass tube was cooled, it was filtered and collected, washed three times with DMF and THF respectively, and vacuum dried to obtain a reddish-brown crystalline powder, namely HTA-BDU-COF.

[0047] The reaction process is:

[0048]

[0049] The HTA-BDU-COF polymer prepared in this example was characterized. Figure 1 is the scanning electron microscope image of HTA-BDU-COF polymer. Figure 2 Thermogravimetric image of HTA-BDU-COF polymer. Figure 3 is the PXRD pattern of HTA-BDU-COF polymer, Figure 4 This is the N2 adsorption image of HTA-BDU-COF polymer. Figure 1 , Figure 3 and Figure 4 It can be seen from the above that the HTA-BDU-COF polymer prepared in this example has a porous structure. Figure 2-Figure 3 It can be seen that the HTA-BDU-COF polymer is a crystalline porous material with high thermal stability.

[0050] Example 3

[0051] The difference from Example 2 is that the molar ratio of HTA to BDU is 1:0.8, and the other preparation processes are exactly the same as those in Example 2, but the HTA-BDU-COF polymer cannot be synthesized.

[0052] Example 4

[0053] The difference from Example 2 is that the molar ratio of HTA to BDU is 1:1.2, and the other preparation processes are exactly the same as those in Example 2, but the HTA-BDU-COF polymer cannot be synthesized.

[0054] Catalytic performance

[0055] The HTA-BDU-COF polymer prepared in Example 2 of the present invention is used as a catalyst to catalyze the Friedel-Crafts reaction of trans-nitrostyrene and indole.

[0056] The preparation process is as follows: β-nitrostyrene (73.68 mg, 0.50 mmol), indole (87 mg, 0.74 mmol), 2.0 mol% catalyst, the reactants are mixed and dissolved in 0.5 ml of dichloromethane, stirred at room temperature for 24 hours, and the product is separated and purified by column chromatography (dichloromethane: petroleum ether = 1:1) to obtain a white solid product 3-(2-nitro-1-phenylethyl)-1H-indole, and the reaction yield is determined by gas chromatography-mass spectrometry (GC-MS).

[0057] The specific reaction equation is as follows:

[0058]

[0059] The reaction was tracked by TLC. After the reaction was completed, the catalyst was recovered by centrifugation and directly put into the next cycle reaction. According to the above conditions, the catalyst was used for six cycles. The reaction solution was separated and the yield was calculated. The catalytic effect is shown in Table 1. Figure 5 The PXRD pattern of the catalyst after 5 cycles. Figure 5 It can be seen that after the catalyst was cycled 5 times, the HTA-BDU-COF framework did not change. As can be seen from Table 1, the yield of the product remained basically the same, and after six cycles, it only showed a slight downward trend, reflecting the excellent stability of the catalyst, which can be reused more than six times, can significantly improve the utilization rate of the catalyst, and reduce production costs.

[0060] Table 1 Catalytic effect of HTA-BDU-COF multiple cycle reactions

[0061]

[0062] When the HTA-BDU-COF polymer provided by the present invention is used as a catalyst and dichloromethane is used as a solvent to catalyze the Friedel-Crafts reaction of trans-nitrostyrene and indole, the yield can be as high as 77%. At the same time, after six cycles of reaction, the HTA-BDU-COF polymer still maintains a catalytic yield of more than 92%, which proves that the HTA-BDU-COF polymer provided by the present invention has efficient and stable catalytic performance and can be recycled multiple times.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A HTA-BDU-COF polymer, characterized in that The structure shown in formula (I) is the structural repeating unit: Formula (I).

2. A method for preparing the HTA-BDU-COF polymer according to claim 1, characterized in that: The following steps are involved: (1) mixing 1,4-phenylene diisocyanate with aqueous ammonia to react and prepare 1,4-diphenylurea; (2) 2-Hydroxy-1,3,5-benzenetricarboxaldehyde, 1,4-diphenylurea and acetic acid were reacted to prepare HTA-BDU-COF polymer.

3. The method for preparing the HTA-BDU-COF polymer according to claim 2, characterized in that: In step (1), the concentration of the aqueous ammonia is 25-30 mol·L -1 ; The mixing ratio of the 1,4-phenylene diisocyanate to aqueous ammonia is (1.0-1.5) g: (0.3-0.5) mol.

4. The method for preparing the HTA-BDU-COF polymer according to claim 2, characterized in that: In step (1), the reaction is carried out at 0-5°C for 1-3 hours, and then the temperature is raised to room temperature for 3-5 hours; After the reaction is completed, filtering, washing and drying are further performed, wherein the washing is performed with water-tetrahydrofuran in a volume ratio of (1-3):1; The drying is vacuum drying at room temperature.

5. The method for preparing the HTA-BDU-COF polymer according to claim 2, characterized in that: In step (2), the molar ratio of 2-hydroxy-1,3,5-benzenetricarboxaldehyde, 1,4-diphenylurea and acetic acid is 1:1:1.5×10 -3 .

6. The method for preparing the HTA-BDU-COF polymer according to claim 2, characterized in that: In step (2), the solvent used in the reaction consists of o-dichlorobenzene and tert-butanol, and the volume ratio of o-dichlorobenzene to tert-butanol is 1.8 to 2.2:1, preferably 2:

1.

7. The method for preparing the HTA-BDU-COF polymer according to claim 2, characterized in that: In step (2), the concentration of 2-hydroxy-1,3,5-benzenetricarboxaldehyde in the solvent is 2 to 4 mmol / L, preferably 3 mmol / L; The concentration of the acetic acid is 5-6 mol·L -1 .

8. The method for preparing the HTA-BDU-COF polymer according to claim 2, characterized in that: In step (2), the reaction temperature is 110-130°C, preferably 120°C; the reaction time is 90-100h, preferably 92h; After the reaction is completed, washing and drying are further performed; the washing is performed using dimethylformamide and tetrahydrofuran respectively; and the drying is performed by vacuum drying.

9. Use of the HTA-BDU-COF polymer according to claim 1 in catalyzing the Friedel-Crafts reaction of trans-nitrostyrene and indole.

10. A method for catalyzing the Friedel-Crafts reaction of trans-nitrostyrene and indole, characterized in that: The HTA-BDU-COF polymer described in claim 1 is used as a catalyst, β-nitrostyrene and indole are used as raw materials, added into dichloromethane, and stirred for reaction at room temperature.

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