Preparation and application of an imine porous organic framework material

Abstract

The invention provides a method for preparing an imine porous organic skeleton material. By utilizing the coupling reaction between an aldehyde group and an amine group, a dialdehyde raw material (p-diformyl azobenzene) and a tetraamine raw material (1,4,8,11-tetramethylbenzyl tetraazacyclotetradecane) are reacted at room temperature to successfully prepare a novel porous organic material, which is obtained by connecting an imine bond and has multiple functional groups such as an imine bond, an azo bond, and a nitrogen heterocycle, and is proved to have a high specific surface area by nitrogen adsorption and desorption. In addition, it can also be used as an efficient and stable catalyst for the cycloaddition of carbon dioxide.

Description

Technical Field

[0001] The invention relates to a method for preparing an imine porous organic skeleton material and also to application of the material in catalyzing the cycloaddition reaction of epichlorohydrin and CO2, belonging to the field of preparation of functionalized porous materials. Background Art

[0002] With the development of porous materials, functional porous materials are precisely designed to solve specific problems. Among them, porous organic framework materials (POF) are a new type of porous materials formed by connecting organic units together with chemical bonds. POF has many advantages over traditional porous materials. First, it connects each unit with chemical bonds, and the overall stability is very high, so it can be used in harsh environments; secondly, the cross-linked network structure also gives it a higher specific surface area; thirdly, it is composed of small organic units, which can be precisely designed according to needs, and due to the rich functional groups on the surface, its functionalization can be conveniently achieved through post-modification. The present invention uses a dialdehyde azo raw material and a tetraamine azocycloalkane raw material to obtain a new type of POF through an imine bond. It has a stable structure and a large specific surface area. Summary of the invention

[0003] The purpose of the present invention is to provide a method for preparing an imine porous organic framework material, and at the same time provide an application of the material in catalyzing the cycloaddition reaction of epichlorohydrin and CO2.

[0004] 1. Preparation of Imine Porous Organic Framework Materials

[0005] (1) Synthesis of p-dimethylhydroxyazobenzene

[0006] Under nitrogen protection, 4-nitrobenzyl alcohol and sodium hydroxide solution are mixed, reacted at 45-55°C for 1-2 hours, and then D-glucose aqueous solution is added, and the mixed reaction solution is blown with air for 2.5-3.5 hours; the mixture is transferred to room temperature, stirred and reacted under nitrogen environment for 10-14 hours, and after the reaction is completed, acetic acid aqueous solution is added dropwise to make the pH of the crude product 4-5; the filter cake is then obtained by suction filtration, and is fully washed with distilled water and placed in an oven for drying and dehydration; after drying, the dried filter cake is dissolved with ethanol aqueous solution, and the orange-yellow product p-dimethylhydroxyazobenzene is obtained by recrystallization. Among them, the molar ratio of 4-nitrobenzyl alcohol to sodium hydroxide is 1:10-1:15; the molar ratio of 4-nitrobenzyl alcohol to D-glucose is 1:5-1:6.

[0007] (2) Synthesis of diformyl azobenzene

[0008] Under ice bath conditions, p-dimethylhydroxyazobenzene is dispersed in chloroform, and then Dess-Martin oxidant is added. After reacting for 12 to 18 minutes, the ice bath is removed and the reaction is carried out at room temperature for 10 to 14 hours. After the reaction is completed, a saturated sodium bicarbonate aqueous solution is first added dropwise until no bubbles are generated, and then the organic layer is obtained by separation, and dried over anhydrous magnesium sulfate, and the magnesium sulfate is filtered to remove the organic phase. The organic phase is concentrated by rotary evaporation, and finally the product is purified by column chromatography. The molar ratio of p-dimethylhydroxyazobenzene to Dess-Martin oxidant is 1:2 to 1:3.

[0009] (3) Synthesis of 1,4,8,11-Tetramethylbenzene nitrotetraazacyclotetradecane

[0010] The acetonitrile solution of tetraazacyclotetradecane and the aqueous sodium hydroxide solution are mixed, and then p-nitrobenzyl bromide is added and reacted at room temperature for 10 to 15 hours. After the reaction is completed, the crude product is extracted with dichloromethane, dried over anhydrous magnesium sulfate, filtered and concentrated by rotary evaporation, and finally purified by column chromatography to obtain the product. The molar ratio of tetraazacyclotetradecane to p-nitrobenzyl bromide is 1:4 to 1:4.2.

[0011] (4) Synthesis of 1,4,8,11-Tetramethylaminotetraazacyclotetradecane

[0012] 1,4,8,11-tetramethylbenzene nitrotetraazacyclotetradecane and concentrated hydrochloric acid are mixed at 60-80°C, and then stannous chloride is added, and the mixture is reacted under stirring and reflux for 7.5-8.5 hours. After the reaction is completed, a filter cake is obtained by suction filtration, and the filter cake is dissolved in a sodium hydroxide solution and extracted with dichloromethane. The obtained organic phase is then dried over anhydrous magnesium sulfate, concentrated by rotary evaporation, and then dried in a vacuum to obtain the product. The mass ratio of 1,4,8,11-tetramethylbenzene nitrotetraazacyclotetradecane to concentrated hydrochloric acid is 1:50-1:80, and the molar ratio of 1,4,8,11-tetramethylbenzene nitrotetraazacyclotetradecane to stannous chloride is 1:20-1:25.

[0013] (5) Preparation of imine porous organic materials

[0014] The p-diformyl azobenzene and 1,4,8,11-tetramethylphenylamine tetraazacyclotetradecane were mixed and dissolved in chloroform in a molar ratio of 2:1, sealed, and allowed to react for 70-75 hours. After the reaction was completed, a solid was obtained by suction filtration. The solid was then washed with chloroform and dried in vacuum.

[0015] Figures 1 to 4 They are the nuclear magnetic hydrogen spectra of p-dimethylhydroxyazobenzene, p-diformylazobenzene, 1,4,8,11-tetramethylbenzene nitrotetratetraazacyclotetradecane and 1,4,8,11-tetramethylbenzene aminotetraazacyclotetradecane, respectively. 1H NMR fully shows that the synthesis of these four raw materials is successful.

[0016] 2. Structure of Imine Porous Organic Framework Materials

[0017] 1. FT-IR and XRD characterization

[0018] The characteristic functional groups of the materials were analyzed by FT-IR, such as Figure 5 , and found that 1490 cm -1 、1105 cm -1 、1630cm -1 The vibration peaks that appeared were attributed to N=N of the azo raw material, NC of the tetraamine raw material, and C=N produced after the reaction of the two raw materials, proving that the two raw materials successfully reacted to prepare a material connected by an imine bond. XRD characterization of the material revealed that Figure 6 , proving that it has a certain crystal structure.

[0019] 2. BET specific surface area determination

[0020] The specific surface area of ​​the material was measured by nitrogen adsorption and desorption. The results are as follows: Figure 7 The isothermal adsorption curve of the material is type III, indicating that the interaction between it and nitrogen is very weak. The S BET 62.85m 2 / g.

[0021] 3. Study on Catalytic Performance

[0022] The synthesized imine porous organic material catalyst was used to catalyze the cycloaddition reaction of CO2. The reaction conditions were 0.1Mpa, 80°C, 10mg of catalyst, 10mmol of epichlorohydrin, and 0.1mmol% of the co-catalyst tetrabutylammonium bromide (TBAB) of epichlorohydrin. The cycloaddition reaction formula is as follows:

[0023]

[0024] Four experimental groups were set up, namely, no catalyst and co-catalyst, single co-catalyst, single catalyst, and co-catalyst and catalyst. 1 The reaction conversion rate was calculated based on the results of HNMR, as shown in Table 1.

[0025] The recyclability of the catalyst was also determined by collecting the catalyst by filtration, washing it three times with dichloromethane, and then drying it in vacuo at 40° C. The dried catalyst was put into the next reaction and the cycle was repeated four times.

[0026]

[0027] aReaction conditions: epichlorohydrin = 10 mmol, P CO2 =0.1Mpa, T=80 o C, reaction time = 12 h, catalyst = 10 mg, TBAB = 0.1 mmol.

[0028] This imine porous organic framework material was used to catalyze the cycloaddition reaction of epichlorohydrin and CO2. The results are shown in Table 1: the catalytic ability of a single catalyst for the reaction is very weak, but when TBAB is added to the system to form a binary catalytic system, the conversion rate reaches 84.7%.

[0029] The recyclability of the catalyst was then determined, such as Figure 8 The results showed that after three cycles, the conversion rate was still 78.6%, proving the good recyclability of the catalyst.

[0030] In summary, the present invention utilizes the coupling reaction between aldehyde and amine groups to react the dialdehyde raw material (p-diformyl azobenzene) and the tetraamine raw material (1,4,8,11-tetramethylbenzene tetraazacyclotetradecane) at room temperature to successfully prepare a new type of porous organic material. 1 Its basic structure was confirmed by HNMR and FT-IR, and its crystal structure was shown by XRD. The S BET 62.85m 2 / g. Finally, the material was used to catalyze the cycloaddition reaction of epichlorohydrin and CO2, with a conversion rate of 84.7, and after three cycles, the conversion rate was still 78.6%. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the H NMR spectrum of p-dimethylhydroxyazobenzene (DMSO-d6, 400MHz);

[0032] Figure 2 This is the H NMR spectrum of p-diformylazobenzene (CDCl3, 400MHz);

[0033] Figure 3 The H NMR spectrum of 1,4,8,11-tetramethylbenzene nitrotetraazacyclotetradecane (CDCl3, 400 MHz);

[0034] Figure 4 The H NMR spectrum of 1,4,8,11-tetramethylanilinium tetraazacyclotetradecane (CDCl3, 400 MHz);

[0035] Figure 5 FT-IR characterization of imine porous organic materials;

[0036] Figure 6XRD characterization of imine porous organic materials;

[0037] Figure 7 This is the nitrogen adsorption-desorption curve of the imine porous organic material;

[0038] Figure 8 The catalyst is recyclable. DETAILED DESCRIPTION Example

[0039] (1) Synthesis of p-dimethylhydroxyazobenzene

[0040] Under nitrogen protection, 4-nitrobenzyl alcohol (3 g) and 75 mL sodium hydroxide solution (0.18 g / mL) were mixed in a three-necked flask. After reacting at 50°C for 1 h, 40 mL D-glucose aqueous solution (0.5 g / mL) was added dropwise using a constant pressure dropping funnel. Subsequently, the mixed reaction solution was blown with air for 3 h. The beaker was moved to room temperature and stirred overnight under nitrogen. After the reaction was completed, 50% acetic acid aqueous solution was first added dropwise to make the pH of the crude product 4-5. Subsequently, the filter cake was obtained by suction filtration, and was fully washed with distilled water and dried in an oven to remove water. After drying, the dried filter cake was dissolved with boiling 50% ethanol aqueous solution, and the orange-yellow target product was obtained by recrystallization.

[0041]

[0042] (2) Synthesis of diformyl azobenzene

[0043] Under ice bath conditions, p-dimethylhydroxyazobenzene (0.5 g) was dispersed in 50 mL of chloroform, and then Dess-Martin oxidant (2 g) was added. After reacting for 15 min, the ice bath was removed and the reaction was carried out at room temperature for 12 h. After the reaction was completed, a saturated sodium bicarbonate aqueous solution was first added dropwise until no bubbles were generated, and then the organic layer was obtained by separation, and dried over anhydrous magnesium sulfate, and the magnesium sulfate was removed by filtration. The organic phase was concentrated by rotary evaporation, and finally purified by column chromatography (eluent: chloroform) to obtain the product.

[0044]

[0045] (3) Synthesis of 1,4,8,11-Tetramethylbenzene nitrotetraazacyclotetradecane

[0046] First, a solution of tetraazacyclotetradecane (0.6 g) in acetonitrile (30 mL) was mixed with 30 mL of sodium hydroxide aqueous solution (40 g / mL), followed by the addition of p-nitrobenzyl bromide (2.6 g) and the reaction was stirred at room temperature for 12 h. After the reaction was completed, the crude product was extracted with dichloromethane, dried over anhydrous magnesium sulfate, filtered, concentrated by rotary evaporation, and finally purified by column chromatography (eluent: dichloromethane: petroleum ether = 9:1) to obtain the product.

[0047]

[0048] (4) Synthesis of 1,4,8,11-Tetramethylaminotetraazacyclotetradecane

[0049] First, 1,4,8,11-tetramethylbenzene nitro tetraazacyclotetradecane (0.72 g) was mixed with 60 mL of concentrated hydrochloric acid at 70°C, and then stannous chloride (3.8 g) was added and reacted under stirring and reflux for 8 h. After the reaction was completed, a filter cake was obtained by suction filtration, and the filter cake was dissolved in a sodium hydroxide solution and extracted with dichloromethane. The obtained organic phase was then dried over anhydrous magnesium sulfate, concentrated by rotary evaporation, and vacuum dried at 35°C to obtain the product.

[0050]

[0051] Figure 4 Synthesis of 1,4,8,11-Tetramethylanilino-tetraazacyclotetradecane

[0052] (5) Preparation of imine porous organic materials

[0053] Dissolve p-diformyl azobenzene (0.48 g) and 1,4,8,11-tetramethylbenzyl tetraazacyclotetradecane (0.62 g) in 30 mL of chloroform, mix well, seal, and react for 72 hours. After the reaction is completed, filter to obtain a solid. The solid is then washed with chloroform and dried overnight in a vacuum oven at 40°C.

Claims

1. A method for preparing an imine porous organic framework material, comprising the following steps: (1) Synthesis of p-dimethylhydroxyazobenzene Under nitrogen protection, 4-nitrobenzyl alcohol and sodium hydroxide solution are mixed, reacted at 45-55°C for 1-2 h, D-glucose aqueous solution is added, and the mixed reaction solution is blown with air for 2.5-3.5 h; the mixture is transferred to room temperature, stirred and reacted under nitrogen environment for 10-14 h, and after the reaction is completed, acetic acid aqueous solution is added dropwise to make the pH of the crude product 4-5; the filter cake is then obtained by suction filtration, and is fully washed with distilled water and placed in an oven for drying and dehydration; after drying, the dried filter cake is dissolved with ethanol aqueous solution, and the orange-yellow product p-dimethylhydroxyazobenzene is obtained by recrystallization; (2) Synthesis of diformyl azobenzene Under ice bath conditions, p-dimethylhydroxyazobenzene is dispersed in chloroform, and then a Dess-Martin oxidant is added. After reacting for 12 to 18 minutes, the ice bath is removed and the reaction is carried out at room temperature for 10 to 14 hours. After the reaction is completed, a saturated sodium bicarbonate aqueous solution is first added dropwise until no bubbles are generated, and then an organic layer is obtained by separation, and dried over anhydrous magnesium sulfate, and magnesium sulfate is removed by filtration. The organic phase is concentrated by rotary evaporation, and finally the product is purified by column chromatography. (3) Synthesis of 1,4,8,11-Tetramethylbenzene nitrotetraazacyclotetradecane The acetonitrile solution of tetraazacyclotetradecane and the aqueous solution of sodium hydroxide are mixed, and then p-nitrobenzyl bromide is added, and the reaction is carried out at room temperature for 10 to 15 hours; after the reaction is completed, the crude product is extracted with dichloromethane, dried over anhydrous magnesium sulfate, filtered, concentrated by rotary evaporation, and finally purified by column chromatography to obtain the product; (4) Synthesis of 1,4,8,11-Tetramethylaminotetraazacyclotetradecane 1,4,8,11-tetramethylbenzene nitrotetraazacyclotetradecane and concentrated hydrochloric acid are mixed at 60-80°C, and then stannous chloride is added, and the mixture is reacted under stirring and reflux for 7.5-8.5 hours. After the reaction is completed, a filter cake is obtained by suction filtration, and the filter cake is dissolved in a sodium hydroxide solution and extracted with dichloromethane. The obtained organic phase is then dried over anhydrous magnesium sulfate, concentrated by rotary evaporation, and then dried in vacuum to obtain the product. (5) Preparation of imine porous organic materials The p-diformyl azobenzene and 1,4,8,11-tetramethylphenylamine tetraazacyclotetradecane were mixed and dissolved in chloroform in a molar ratio of 2:1, sealed, and allowed to react for 70-75 hours. After the reaction was completed, a solid was obtained by suction filtration. The solid was then washed with chloroform and dried in vacuum.

2. The method for preparing the imine porous organic framework material according to claim 1, characterized in that: In step (1), the molar ratio of 4-nitrobenzyl alcohol to sodium hydroxide is 1:10-1:15; the molar ratio of 4-nitrobenzyl alcohol to D-glucose is 1:5-1:

6.

3. The method for preparing the imine porous organic framework material according to claim 1, characterized in that: In step (2), the molar ratio of p-dimethylhydroxyazobenzene to Dess-Martin oxidant is 1:2 to 1:

3.

4. The method for preparing the imine porous organic framework material according to claim 1, characterized in that: In step (3), the molar ratio of tetraazacyclotetradecane to p-nitrobenzyl bromide is 1:4 to 1:4.

2.

5. The method for preparing the imine porous organic framework material according to claim 1, characterized in that: In step (4), the mass ratio of 1,4,8,11-tetramethylbenzene nitrotetraazacyclotetradecane to concentrated hydrochloric acid is 1:50-1:80; the molar ratio of 1,4,8,11-tetramethylbenzene nitrotetraazacyclotetradecane to stannous chloride is 1:20-1:

25.

6. Use of the imine porous organic framework material prepared according to the method of claim 1 in catalyzing the cycloaddition reaction of epichlorohydrin and CO2.

7. Use of the imine porous organic framework material according to claim 6 in catalyzing the cycloaddition reaction of epichlorohydrin and CO2, characterized in that; The main catalyst is an imine porous organic framework material, and tetrabutylammonium bromide is a co-catalyst.

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