CN110078888B - Porous organic polymer connected by thiourea structure and preparation method and application thereof - Google Patents

Abstract

The invention discloses a porous organic polymer connected with a thiourea structure and a preparation method and application thereof. The preparation method is to add compound II and compound III into an organic solvent under argon or nitrogen atmosphere, and disperse uniformly with ultrasonic waves at room temperature; hour; then, cooling to room temperature, adding acetone to the reaction solution, stirring for 1-2 hours, and then filtering, washing, and drying to obtain a porous organic polymer POP-S connected with a thiourea structure. The porous organic polymer catalytic material connected by the thiourea structure synthesized by the invention has more thiourea structures in its unit pores, and takes the double hydrogen bond of thiourea in the POP-S as the catalytic active center, which can efficiently catalyze beta ‑Nitrostyrene undergoes a Michael reaction with diethyl malonate with good solvent tolerance, stability and recyclability.

Description

Porous organic polymer connected by thiourea structure and preparation method and application thereof

technical field

The invention relates to a porous organic polymer, in particular to a porous organic polymer connected by a thiourea structure, a preparation method and an application thereof; it belongs to the organic porous polymer material.

Background technique

Porous organic polymers (POPs) use strong covalent bonds instead of traditional weak chemical bonds to construct rigid frameworks with two-dimensional or three-dimensional structures and nanoscale pore structures with adjustable size. POP materials have the following advantages: (1) the skeleton is mostly composed of light elements, the rigid skeleton has low density and high specific surface area; (2) high thermal stability and chemical stability, in acid, alkali, a variety of common polar It can maintain its characteristics in both polar and non-polar solvents; (3) The structure is highly designable, and the skeleton structure of POP, the required functional groups and the atoms to be introduced can be pre-designed according to the synthesis purpose, so as to adjust the structure of the material. . These advantages of POP materials make them a promising framework for heterogeneous catalysts, which have received increasing attention in recent years.

Organic small-molecule catalysts refer to catalysts composed only of non-metallic elements such as C, N, O, and S, and are the third type of catalysts that are widely used after enzyme catalysts and metal complex catalysts. The organic compound containing thiourea structure is a kind of organic small molecule catalyst with strong hydrogen bond activation function. It has the unique advantages of cheap and readily available raw materials, mild reaction conditions, easy structural modification, and low requirements for the catalyzed reaction conditions. . The fly in the ointment is that the catalytic efficiency of this organic compound containing thiourea structure is not high, the amount of catalyst is usually more than 20% of the molar equivalent of the catalyzed substrate, and it is difficult to separate and reuse after the reaction. This undoubtedly greatly limits their application in the field of catalysis.

Traditional heterogeneous catalysts, such as zeolites, have good stability and are easy to recycle, and have dominated industrial applications. However, the structural modifiability and designability of traditional heterogeneous catalysts are very limited, and it is difficult to meet the requirements of diverse catalytic systems, so the application scope of such heterogeneous catalysts is also greatly limited. Therefore, the development of a new heterogeneous catalyst that integrates the characteristics and advantages of heterogeneous catalysts and organic small molecule catalysts has important theoretical research value and practical application prospects for the development of green catalysis and the realization of high-efficiency catalysis.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a porous organic polymer POP-S connected with a thiourea structure and a preparation method thereof, and the prepared porous organic polymer POP-S connected with a thiourea structure reacts to the selected model, That is, the Michael reaction of β-nitrostyrene and diethyl malonate has high catalytic efficiency, and the catalyst dosage can be as low as 0.04mol% of the reaction substrate β-nitrostyrene; The organic polymer POP-S also has good solvent tolerance, thermal stability and recyclability.

Another object of the present invention is to provide the application of the porous organic polymer POP-S linked by a thiourea structure as a heterogeneous catalyst.

In the prior art, the amount of thiourea small-molecule catalyst is usually more than 20 mol% of the substrate β-nitrostyrene. By introducing a thiourea structure into the POP skeleton, the present invention combines the catalytic active center structure of an organic small molecule catalyst with good catalytic performance and the advantages of a heterogeneous catalyst with high specific surface area, high stability, and easy recycling. A new class of heterogeneous catalysts with no supported metal, high catalytic efficiency, easy separation and recyclability was prepared. This new type of heterogeneous catalyst with POP as the skeleton has high atom economy, does not need to support metal, and has excellent recyclability and reuse performance, which is in line with the concept and development trend of green chemistry and sustainable development.

In the present invention, compound II and compound III are used as monomers to prepare porous organic polymer POP-S connected by thiourea structure; the double hydrogen bond catalysis of thiourea contained in the POP-S skeleton can be used efficiently without loading metal. Catalytic Michael reaction of β-nitrostyrene with diethyl malonate. The porous organic polymer POP-S prepared by the invention has a novel structure and has not been reported so far; POP-S has high catalytic efficiency for Michael reaction, and the catalyst dosage is significantly lower than that of the existing reported thiourea small molecule catalyst. More importantly, after the catalytic reaction is completed, the porous organic polymer POP-S prepared by the present invention is easy to be recycled and reused, and its catalytic ability is not significantly reduced after being recycled for many times.

The object of the present invention is achieved through the following technical solutions:

A porous organic polymer whose structural formula is:

wherein, R ₁ is N or C ₆ H ₃ .

The preparation method of the porous organic polymer: in an argon or nitrogen atmosphere, compound II and compound III are added into an organic solvent, and uniformly dispersed by ultrasonic waves at room temperature; after 2 to 4 times of deoxygenation by freezing, Heating to a certain reaction temperature for a certain period of time; then, cooling to room temperature, adding a large amount of acetone to the reaction solution, stirring for 1 to 2 hours, and then filtering, washing and drying to obtain a porous organic polymer connected with a thiourea structure POP-S.

The compound II is tris(4-aminophenyl)amine or 1,3,5-tris(4-aminophenyl)benzene; the compound III is p-phenylenediisothiocyanate; the The molar ratio of compound II and compound III is 2:3 to 2:3.5.

In order to further achieve the object of the present invention, preferably, the organic solvent is mesitylene, N,N-dimethylformamide (DMF), ethanol or 1,4-dioxane, and other organic solvents can also be selected. Solvent; the mass-volume ratio of compound II to the organic solvent is 100:5 to 100:20, the mass unit is mg, and the volume unit is mL.

Preferably, the reaction temperature is 60-120°C, and the certain time is 24-72 hours.

Taking the Michael reaction between β-nitrostyrene and diethyl malonate as a model reaction, the porous organic polymer POP-S was used to catalyze the Michael reaction.

The application of the porous organic polymer connected by the thiourea structure: dissolve β-nitrostyrene and diethyl malonate in an organic solvent, stir evenly, add alkali and the porous organic polymer connected by the thiourea structure POP-S catalyst, heated to 25～60℃ and reacted for 24～48 hours; then, filter off the catalyst, spin off the solvent under reduced pressure, and then purify by column chromatography to obtain β-nitrostyrene and malonic acid The product of Michael reaction of ethyl ester is 2-(2-nitro-1-phenylethyl) diethyl malonate; the molar ratio of β-nitrostyrene and diethyl malonate is 1:1～ 1:5.

The Michael reaction catalyzed by POP-S is shown in the reaction formula (1):

Reaction formula (1) is as follows:

Preferably, the organic solvent is mesitylene or toluene; the mass-volume ratio of β-nitrostyrene to the organic solvent is 100:1 to 100:5, the mass unit is mg, and the volume unit is mL.

Preferably, the molar ratio of the porous organic polymer POP-S catalyst to β-nitrostyrene is 0.0004:1 to 0.025:1.

Preferably, the base is potassium carbonate, and the molar ratio of the base to β-nitrostyrene is 0.2:1 to 1:1; the eluent used in the column chromatography is a volume ratio of 20: 1-15:1 petroleum ether/ethyl acetate mixture.

The porous organic polymer POP-S of the present invention is prepared by the reaction of compounds II and III, and the synthesis reaction of the POP-S is shown in the reaction formula (2).

Reaction formula (2) is as follows:

In the present invention, β-nitrostyrene and diethyl malonate are selected as reaction substrates, and the Michael reaction of β-nitrostyrene and diethyl malonate is used as a model reaction. The organic polymer POP-S was used as the catalyst for this model reaction.

Compared with the existing POPs materials, the advantages of the present invention are:

(1) The present invention has synthesized a novel porous organic polymer POP-S connected by a thiourea structure, the unit pores of which have more catalytic center thiourea structures, and can be used as a heterogeneous catalyst without supporting metals.

(2) The porous organic polymer POP-S synthesized by the present invention connected with a thiourea structure has high catalytic efficiency for Michael reaction, and the catalyst dosage is significantly lower than that of the existing reported thiourea small molecule catalysts, which can efficiently catalyze β - Nitrostyrene undergoes a Michael reaction with diethyl malonate and has good solvent tolerance, thermal stability and recyclability.

(3) The present invention successfully combines the catalytic function of the organic small molecule catalyst with the skeleton structure of the POP material, which greatly expands the application field of the porous organic polymer material. POP material.

(4) Compared with the existing thiourea small-molecule catalyst, the porous organic polymer POP-S connected by the thiourea structure of the present invention greatly reduces the amount of catalyst and greatly improves the efficiency and economy.

Description of drawings

FIG. 1 is an infrared spectrum (FT-IR) of the porous organic polymer POP-S prepared in Example 1 and its reactants, namely Compound II and Compound III.

FIG. 2 is a solid-state nuclear magnetic spectrum (Solid-NMR) of the porous organic polymer POP-S prepared in Example 1. FIG.

FIG. 3 is a scanning electron microscope (SEM) image of the porous organic polymer POP-S prepared in Example 1. FIG.

4 is the N ₂ adsorption and desorption isotherm curves of the porous organic polymer POP-S prepared in Example 1.

FIG. 5 is the thermogravimetric analysis curve (TGA) of the porous organic polymer POP-S prepared in Example 1. FIG.

6 is the N ₂ adsorption and desorption isotherm curves of the porous organic polymer POP-S prepared in Example 2.

FIG. 7 is a scanning electron microscope (SEM) image of the porous organic polymer POP-S prepared in Example 3. FIG.

8 is the N ₂ adsorption and desorption isotherm curves of the porous organic polymer POP-S prepared in Example 3.

9 is the N ₂ adsorption and desorption isotherm curves of the porous organic polymer POP-S prepared in Example 4.

Figure 10-1 is the ¹ H NMR spectrum of diethyl 2-(2-nitro-1-phenylethyl)malonate, the reaction product obtained by using porous organic polymer POP-S to catalyze Michael's reaction in Example 5 picture.

Figure 10-2 is the ¹³ C NMR spectrum of diethyl 2-(2-nitro-1-phenylethyl)malonate, the reaction product obtained by using porous organic polymer POP-S to catalyze Michael's reaction in Example 5 picture.

11 is a graph showing the relationship between the yield and the number of cycles of the Michael reaction of β-nitrostyrene and diethyl malonate catalyzed by the porous organic polymer POP-S for multiple cycles in Example 8.

Detailed ways

In order to better understand the present invention, the present invention will be further described below with reference to the accompanying drawings and embodiments, but the embodiments of the present invention are not limited thereto.

Example 1 Synthesis of Porous Organic Polymer POP-S

145 mg (0.5 mmol) of compound II tris(4-aminophenyl)amine and 144 mg (0.75 mmol) of compound III p-phenylenediisothiocyanate were respectively dissolved in 5 mL of N,N-dimethylmethane under argon atmosphere. amide, add compound II solution dropwise to compound III solution, ultrasonically disperse for 3 minutes, freeze and deoxygenate 3 times; heat to 60 ° C, react for 72 hours, cool to room temperature, add 50 mL of acetone, stir for 1 hour, filter, Washing with dichloromethane, acetone, methanol, and water in turn was repeated three times to remove unreacted monomers. The obtained solid product was vacuum-dried at 80° C. for 24 hours to obtain 216 mg of brown solid POP-S (yield 74.7%).

Figure 1 is the infrared spectrum of the porous organic polymer POP-S prepared in Example 1 and its reactants, namely Compound II and Compound III. Comparing the infrared spectra of these three compounds, it can be seen that the NH bending vibration peaks of compound II at 3400cm ^-1 and 3340cm ^-1 and the N=C=S cumulative double bond vibration peak of compound III at 2080cm ^-1 are in the porous The organic polymer POP-S basically disappeared in the spectrum, indicating that compound II and compound III were completely consumed; in addition, in the infrared spectrum of POP-S, the CN stretching vibration peak appeared at 1500 cm ^-1 and the C peak at 1238 cm ^-1 The =S stretching vibration peak indicates the existence of thiourea structure in the obtained porous organic polymer. The infrared spectrum test uses a Bruker Tensor 27FTIR spectrometer infrared spectrometer, potassium bromide tablet preparation, and the porous organic polymer POP-S is pre-dried.

The reaction equation of the present embodiment is as follows:

FIG. 2 is a solid carbon NMR spectrum of the porous organic polymer POP-S prepared in Example 1. FIG. In this spectrum, the peak at 180 ppm corresponds to the C=S carbon in the thiourea structure, and the peaks at 148 ppm and 130 ppm correspond to the aromatic carbons of p-phenylenediisothiocyanate and tris(4-aminophenyl)amine, respectively . Combined with the results in Fig. 1, it is shown that in this example, compound II and compound III undergo the expected reaction to obtain the porous organic polymer POP-S with the expected structure. The test was performed on a Bruker WBAVANCE II 400MHz nuclear magnetic spectrometer. Through the infrared and solid carbon NMR spectra given in Figure 2, combined with the reaction principle, it can be proved that the prepared POP-S has the structure shown in the above reaction formula, which proves that the porous organic polymer POP-S prepared in this example. Structure.

FIG. 3 is a scanning electron microscope (SEM) image of the porous organic polymer POP-S prepared in Example 1. FIG. It can be observed from the figure that POP-S has a loose and porous layered structure with micron-scale irregular concave pores. The scanning electron microscope used was EV018 from Zeiss, Germany.

4 is the _N2 isothermal adsorption-desorption analysis results of the porous organic polymer POP-S prepared in Example 1. The specific surface area of POP-S is the part of the relative pressure less than 0.1 in the _N2 isotherm adsorption-desorption curve, the abscissa of the relative pressure position, the cumulative adsorption volume as the ordinate, and the linear fitting is performed by the BET equation, and the slope of the obtained line is POP- The BET specific surface area of S is 49 m ² g ^-1 , and the average pore size fitted by NLDFT is 9.8 nm, with mesopores as the main pore size. In Figure 4, the curve obtained by the solid circle is the _N2 adsorption isotherm, and the curve obtained by the hollow circle is the _N2 isotherm desorption curve. It can be seen from the comparison of the adsorption curve with the standard adsorption curve that POP-S is a type II isotherm adsorption line, indicating that it contains intermediate pore structure, which is consistent with the analysis of pore size. The specific surface area was analyzed using Micromeritics ASAP 2020M surface area and porosity analyzer.

5 is the thermogravimetric analysis curve (TGA) of the porous organic polymer POP-S prepared in Example 1. Since the thiourea group is very easy to absorb water, the weight loss before 50 °C is the volatilization of water, and the POP-S has obvious weight loss at 180 °C, and the thermal stability is obviously better than that of general thiourea compounds.

Example 2 Synthesis of Porous Organic Polymer POP-S

145 mg (0.5 mmol) of compound II tris(4-aminophenyl)amine and 144 mg (0.75 mmol) of compound III p-phenylenediisothiocyanate were dissolved in 5 mL of N,N-dimethylformamide under nitrogen atmosphere, respectively , add compound II solution dropwise to compound III solution, ultrasonically disperse for 3 minutes, freeze and deoxygenate 3 times; heat to 120 ° C, react for 48 hours, cool to room temperature, add 50 mL of acetone, stir for 1 hour, filter, and then Washing with dichloromethane, acetone, methanol, and water was repeated 3 times to remove unreacted monomers. The obtained solid product was vacuum-dried at 80° C. for 24 hours to obtain 219 mg of brown solid POP-S (yield 75.8%).

The infrared spectrum and solid NMR spectrum of the porous organic polymer POP-S prepared in this example are consistent with Figure 1 and Figure 2, respectively, and its scanning electron microscope image is similar to Figure 3, which will not be repeated; its nitrogen adsorption-desorption curve As shown in Fig. 6, the specific surface area of POP-S is linearly fitted by the BET equation with the relative pressure less than 0.1 in the _N2 isotherm adsorption-desorption curve, the abscissa of the relative pressure, and the cumulative adsorption volume as the ordinate. The slope of the obtained straight line is the BET specific surface area of POP-S, which is 31m ² g ^-1 , and the average pore size fitted by NLDFT is 9.2nm, with mesopores as the main pore size. It can be seen from the comparison of the adsorption curve with the standard adsorption line that POP-S is II type of adsorption isotherm, indicating that there is a mesoporous structure, which is consistent with the analysis of the pore size.

Example 3 Synthesis of Porous Organic Polymer POP-S

145 mg (0.5 mmol) of compound II tris(4-aminophenyl)amine and 144 mg (0.75 mmol) of compound III p-phenylenediisothiocyanate were dissolved in 5 mL of ethanol under argon atmosphere, respectively, and the solution of compound II was added dropwise into the compound III solution, ultrasonically dispersed for 3 minutes, refrigerated and deoxygenated 3 times; heated to 60°C, reacted for 72 hours, cooled to room temperature, filtered, washed with dichloromethane, acetone, methanol, and water in turn, repeated 3 times, Unreacted monomers were removed, and the obtained solid product was vacuum-dried at 80° C. for 24 hours to obtain 232 mg of brown granular solid POP-S (yield 80.3%).

The infrared spectrum and solid NMR spectrum of the porous organic polymer POP-S prepared in this example are consistent with Figure 1 and Figure 2, respectively, and will not be repeated; its SEM image is shown in Figure 7, which can be observed from the figure. To the homogeneous spherical structure of POP-S. The nitrogen adsorption and desorption curves of the porous organic polymer POP-S prepared in this example are shown in Fig. 8. The specific surface area of POP-S is represented by the relative pressure in the N isothermal adsorption _- desorption curve less than 0.1, and the relative pressure The abscissa of the position and the ordinate of the accumulated adsorption volume are linearly fitted by the BET equation. The slope of the obtained straight line is the BET specific surface area of POP-S, which is 23 m ² g ^-1 . The average pore size fitted by NLDFT is 7.9 nm. The curve is compared with the standard adsorption line, and it can be seen that POP-S is a type IV isotherm adsorption line, indicating that it contains a mesoporous structure, which is consistent with the analysis results of the pore size.

Example 4 Synthesis of Porous Organic Polymer POP-S

145 mg (0.5 mmol) of compound II tris(4-aminophenyl)amine and 144 mg (0.75 mmol) of compound III p-phenylenediisothiocyanate were respectively dissolved in 5 mL of 1,4-dioxane under nitrogen atmosphere, and the The solution of compound II was added dropwise to the solution of compound III, ultrasonically dispersed for 3 minutes, refrigerated and deoxygenated 3 times; heated to 60°C, reacted for 72 hours, cooled to room temperature, filtered, washed with dichloromethane, acetone, methanol and water in turn , repeated three times to remove unreacted monomers, and the obtained solid product was vacuum-dried at 80° C. for 24 hours to obtain 254 mg of brown solid POP-S (yield 87.9%).

The infrared spectrum and solid NMR spectrum of the porous organic polymer POP-S prepared in this example are consistent with Figure 1 and Figure 2, respectively, and its scanning electron microscope image is similar to Figure 7, which will not be repeated; its nitrogen adsorption and desorption curve As shown in Fig. 9, the specific surface area of POP-S is linearly fitted by the BET equation with the relative pressure less than 0.1 in the _N2 isotherm adsorption-desorption curve, the abscissa of the relative pressure, and the cumulative adsorption volume as the ordinate. The slope of the obtained straight line is the BET specific surface area of POP-S, which is 43 m ² g ^-1 . The average pore size fitted by NLDFT is 12.3 nm, and the comparison of the adsorption curve with the standard adsorption line shows that POP-S is a type IV adsorption isotherm, which is consistent with the analysis results of the pore size.

Example 5 Catalytic performance test of porous organic polymer POP-S

Using the Michael reaction of β-nitrostyrene and diethyl malonate as template reaction, the specific steps are as follows: take the mole number of β-nitrostyrene as 1, add 2 equivalents of diethyl malonate to dissolve In mesitylene, add 0.2 equivalents of potassium carbonate and 0.08 equivalents of POP-S catalyst, and react at 40 ° C for 24 hours; then, filter the catalyst, spin off the solvent under reduced pressure, and use petroleum oil with a volume ratio of 20:1. The ether/ethyl acetate mixture was used as the eluent, and it was purified by column chromatography to obtain the product of the reaction in a yield of 69.3%.

The Michael reaction catalyzed by porous organic polymer POP-S is shown in Equation 1:

Figure 10-1 and Figure 10-2 are the ¹ H NMR spectrum and the ¹³ C of the reaction product diethyl 2-(2-nitro-1-phenylethyl)malonate obtained in Example 5, respectively NMR spectrum. ¹ H NMR (400 MHz, CDCl ₃ ) δ: 7.32-7.26 (m, 3H), 7.24-7.23 (m, 2H), 4.93-4.84 (m, 2H), 4.25-4.19 (m, 3H), 4.00 (q , J=4.4Hz, 2H), 3.82 (d, J=6Hz, 1H), 1.26 (t, J=4.8Hz, 3H), 1.04 (t, J=4.8Hz, 3H). ¹³ C NMR (400 MHz, CDCl ₃ ) δ: 167.49, 166.84, 136.27, 128.95, 128.36, 128.04, 77.67, 62.16, 61.89, 55.00, 42.89, 13.97, 13.74.

Example 6 Catalytic performance test of porous organic polymer POP-S

Using the Michael reaction of β-nitrostyrene and diethyl malonate as template reaction, the specific steps are as follows: take the mole number of β-nitrostyrene as 1, add 1.5 equivalents of diethyl malonate to dissolve in In mesitylene, add 1 equivalent of potassium carbonate and 0.08 equivalent of POP-S catalyst, and react at 60 ° C for 48 hours; then, filter out the catalyst, spin off the solvent under reduced pressure, and use petroleum oil with a volume ratio of 20:1. The ether/ethyl acetate mixture was used as the eluent, and it was purified by column chromatography to obtain the product of the reaction in a yield of 67.1%.

The Michael reaction catalyzed by porous organic polymer POP-S is shown in Equation 1.

Example 7 Influence of different ratios of catalysts on the Michael reaction of β-nitrostyrene and diethyl malonate

Table 1 is a comparison of the product yields of the Michael reaction catalyzed by adding different proportions of porous organic polymer POP-S under the same reaction conditions as in Example 5. The addition amount of POP-S catalyst was from 2.5 mol% to 0.04 mol%, and the reaction yield did not change much, all above 64%, and the dosage was much lower than that of the reported thiourea small molecule catalyst up to more than 20 mol% of the substrate , which indicates that the porous organic polymer POP-S has excellent catalytic activity. Since the thiourea group can form double hydrogen bonds with functional groups such as C=O, C=N and N=O in the substrate, it reduces the electron cloud density of the electrophile, activates the electrophile, and makes it easier to be hydrophilic The nuclear reagents attack, and the reaction proceeds quickly and efficiently. There are many thiourea groups in the POP-S skeleton, the double hydrogen bond catalytic effect is strong, coupled with the special pore structure, the specific surface area is large, so that POP-S can efficiently catalyze β-nitrobenzene with a small amount of Ethylene undergoes Michael reaction with diethyl malonate.

Table 1. Different ratios of porous organic polymers POP-S catalyzed Michael reaction

In Table 1, the amounts of catalyst and base are calculated on the basis of moles of substrate β-nitrostyrene.

Example 8 Cyclic catalytic performance test of porous organic polymer POP-S

The Michael reaction of β-nitrostyrene and diethyl malonate was used as the template reaction to test the cyclic catalytic ability of the porous organic polymer POP-S. The steps are as follows: 75mg (0.5mmol) β-nitrostyrene and 160 mg (1 mmol) of diethyl malonate were dissolved in 1 mL of mesitylene, 13.8 mg (0.1 mmol) of potassium carbonate and 4.9 mg (0.002 mmol) of POP-S catalyst were added, and the reaction was carried out at 40 ° C for 24 hours; then, Filter off the catalyst, spin off the solvent under reduced pressure, use the petroleum ether/ethyl acetate mixture with a volume ratio of 20:1 as the eluent, and purify by column chromatography to obtain the product of the reaction 2-(2-nitro -1-phenylethyl)diethyl malonate.

The filtered catalyst was washed successively with dichloromethane, acetone, methanol and water, and repeated 3 times to remove the unreacted substrate. The filtrate was vacuum-dried at 80°C for 24 hours to obtain the recovered catalyst, namely the porous organic polymer POP. -S; The recovered POP-S was used to catalyze the Michael reaction of β-nitrostyrene with diethyl malonate. Such repeated use was used to determine the cyclic catalytic ability of the porous organic polymer POP-S.

11 is a graph showing the relationship between the yield and the number of cycles of catalyzing the Michael reaction of β-nitrostyrene and diethyl malonate for multiple cycles using porous organic polymer POP-S as a catalyst in this example. It can be seen from Figure 11 that the yield of the porous organic polymer POP-S is basically unchanged in the five cycles of catalysis, and its catalytic efficiency can still be maintained, showing excellent recyclability and reuse characteristics.

Example 9 Solvent resistance test of porous organic polymer POP-S

Select the polarity with stronger solubility such as organic solvent dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), ethanol to the porous organic polymer POP-S prepared in Example 1. Solvent tolerance was tested with the following steps: 5 mg of POP-S was placed in a 50 mL round bottom flask, one of the above solvents was added, heated to 100° C. and kept for 1 hour. It was then isolated by filtration and the resulting solid was dried in a vacuum oven at 80°C for 24 hours. The dried POP-S was tested by FT-IR, Solid-NMR and SEM respectively, and the obtained results were compared with the corresponding Figure 1, Figure 2 and Figure 3 respectively, and no obvious difference was found. This shows that the porous organic polymer POP-S connected with thiourea structure prepared by the present invention has good solvent tolerance.

The embodiments of the present invention are not limited by the examples, and any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention should be equivalent substitution methods. Included in the protection scope of the present invention.

Claims (10)

1. A porous organic polymer connected by a thiourea structure, characterized in that the structural formula is:

wherein R is₁Is N or C₆H₃。

2. The method of preparing a porous organic polymer connected by a thiourea structure of claim 1, comprising the steps of: adding the compound II and the compound III into an organic solvent in an argon or nitrogen atmosphere, and uniformly dispersing by using ultrasonic waves at room temperature; after freezing and deoxidizing, heating to 60-120 ℃, and reacting for 24-72 hours; then, cooling to room temperature, adding acetone into the reaction solution, stirring for 1-2 hours, filtering, washing and drying to obtain a porous organic polymer connected by a thiourea structure;

the compound II is tri (4-aminophenyl) amine or 1,3, 5-tri (4-aminophenyl) benzene;

the compound III is p-phenylene diisothiocyanate;

the molar ratio of the compound II to the compound III is 2: 3-2: 3.5.

3. The method of claim 2, wherein the organic solvent is mesitylene, N-Dimethylformamide (DMF), ethanol, or 1, 4-dioxane.

4. The method for preparing the porous organic polymer connected by the thiourea structure according to claim 2, wherein the mass-to-volume ratio of the compound II to the organic solvent is 100: 5 to 100: 20, the mass unit is mg, and the volume unit is m L.

5. The method for preparing the porous organic polymer connected by the thiourea structure according to claim 2, wherein the number of times of freezing and oxygen removal is 2-4.

6. The method for preparing a porous organic polymer connected by a thiourea structure according to claim 2, wherein the acetone is added in an amount of 5 to 10 times the volume of the organic solvent.

7. The application of the porous organic polymer connected by the thiourea structure as the heterogeneous catalyst is characterized in that β -nitrostyrene and diethyl malonate are dissolved in an organic solvent, the mixture is uniformly stirred, potassium carbonate and the porous organic polymer catalyst connected by the thiourea structure are added, the mixture is heated to 25-60 ℃ to react for 24-48 hours, then the catalyst is filtered, the solvent is removed by decompression and purification is carried out by a column chromatography method, and a product 2- (2-nitro-1-phenylethyl) diethyl malonate obtained by the Michael reaction of β -nitrostyrene and diethyl malonate is obtained, wherein the molar ratio of β -nitrostyrene to diethyl malonate is 1: 1-1: 5.

8. The application of the porous organic polymer connected by the thiourea structure as the heterogeneous catalyst is characterized in that the organic solvent is mesitylene, dichloromethane, methanol, N-dimethylformamide or 1, 4-dioxane, the mass-volume ratio of β -nitrostyrene to the organic solvent is 100: 1-100: 5, the mass unit is mg, and the volume unit is m L.

9. The application of the porous organic polymer connected by the thiourea structure as the heterogeneous catalyst according to claim 7, wherein the molar ratio of the porous organic polymer connected by the thiourea structure catalyst to β -nitrostyrene is 0.0004: 1 to 0.025: 1.

10. The application of the porous organic polymer connected by the thiourea structure as the heterogeneous catalyst is characterized in that the molar ratio of the potassium carbonate to the β -nitrostyrene is 0.2: 1-1: 1, and an eluant used in the column chromatography is a petroleum ether/ethyl acetate mixture with the volume ratio of 20: 1-15: 1.

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