Organic acid anion pair polyion liquid as well as preparation method and application thereof

Abstract

The invention relates to an organic acid anion paired polyion liquid catalyst as well as a preparation method and application thereof. Due to environmental pollution caused by halogen, a series of environment-friendly porous polyion liquid catalysts paired with organic acid anions are designed and synthesized, 1-vinyl imidazole and bis (2-chloroethyl) ether are used as raw materials, and the ionic liquid diethyl ether bis (1-vinyl imidazole) chloride is successfully prepared. Divinyl benzene is selected as a cross-linking agent and a structure stabilizer, and a stable copolymer is prepared. The copolymer is put into a sodium hydroxide solution to react for three days, hydroxyl replaces chloride anions to obtain a substance [ECD] OH, the [ECD] OH is put into an organic acid solution to react for three days, and finally, organic acid anions replace halogen anions, so that the pollution to the environment is reduced. The series of catalysts are stable in structure, and can efficiently catalyze carbon dioxide cycloaddition to generate cyclic carbonate under the conditions of no solvent and no cocatalyst.

Description

Technical Field

[0001] The present invention relates to the fields of poly(ionic liquid) and chemical catalysis, and particularly to an organic acid anion-containing poly(ionic liquid) and its application in the preparation of important chemical product carbonates by catalyzing CO2 and epoxides. Background Art

[0002] Carbon dioxide (CO2) is a non-flammable, colorless, and odorless gas. Its greenhouse effect in the atmosphere plays an important role in maintaining the thermal balance of the earth within a habitable range. Through natural photosynthesis and respiration processes, carbon dioxide is also a key component for the survival of animals and plants. However, in recent years, the huge demand for fossil fuels has generated excessive carbon dioxide emissions. Excessive carbon dioxide in the atmosphere will cause more heat to remain on the earth, leading to an increase in the global average temperature, resulting in global warming, which is the main cause of climate change and poses a serious threat to the sustainable development of human society. Some economical and effective methods have been developed to convert CO2 into high-value-added chemicals as a renewable and environmentally friendly C1 resource. In particular, the cycloaddition of CO2 and epoxides to synthesize cyclic carbonates is one of the most effective ways for CO2 chemical conversion due to its high atomic efficiency and wide application. Cyclic carbonates are valuable chemicals and are widely used as aprotic polar solvents, secondary battery electrolytes, polycarbonate monomers, and fine chemical intermediates. Since CO2 is an inert molecule and a thermodynamically very stable molecule, even the highly exothermic cycloaddition reaction of CO2 and epoxides does not occur spontaneously. To solve these problems, a large number of chemists are committed to researching and developing new, highly active, and highly stable catalysts to activate epoxides and CO2, promote the cycloaddition reaction, and achieve the industrial production of cyclic carbonates.

[0003] Cyclic carbonates can be used as components of lithium-ion battery electrolytes. In recent years, with the booming development of new energy vehicles and battery energy storage, the demand for lithium batteries has increased rapidly, and the consumption of cyclic carbonates has also increased rapidly. As is well known, when the halogen concentration in the electrolyte reaches ppm level, it will seriously affect the performance of lithium batteries. Although high-purity cyclic carbonates can be obtained through a series of complex separation processes, this involves high separation costs and will cause halogen pollution and environmental pollution. In the past few decades, many catalysts have been developed for the cycloaddition of carbon dioxide and epoxides to synthesize cyclic carbonates. These catalysts have high catalytic activity, but most of these catalysts are halogen-containing catalysts, and the active catalytic component is still halogen anions. The application of organic acid anion-containing poly(ionic liquid) catalysts provides a halogen-free strategy for the synthesis of cyclic carbonates, reducing the later halogen separation cost and also reducing the environmental pollution caused by halogens. Summary of the Invention

[0004] The object of the present invention is to provide an organic acid anion pair polyionic liquid, which has the advantages of high yield, strong activity, no need for a cocatalyst and other solvents, mild reaction conditions, high stability and no environmental pollution in the synthesis of cyclic carbonates from carbon dioxide and epoxides.

[0005] To achieve the above object, the technical solution of the present invention is as follows. An organic acid anion pair polyionic liquid, wherein the polyionic liquid is composed of a bisimidazole ring cation and an organic acid anion, and the structural formula is shown in formula (I),

[0006]

[0007] wherein, R = CH3CHOHCOO - or OHCH2COO - or CH3COO - .

[0008] The preparation method of the above-mentioned organic acid anion pair polyionic liquid is as follows:

[0009] 1) Weigh 1-vinylimidazole and dissolve it in acetonitrile. Slowly add bis(2-chloroethyl) ether dropwise at 40 °C, and carry out a stirring reaction under a nitrogen atmosphere. Wash with ethyl acetate to remove unreacted substrates, and vacuum dry to obtain the ionic liquid [EEBVIM]Cl2;

[0010] 2) Filter 0.1% TBC stabilizer contained in divinylbenzene DVB through a basic alumina column with 100-200 mesh. Then take [EEBVIM]Cl2, DVB and azobisisobutyronitrile AIBN, dissolve them in a mixed solvent, stir at room temperature until a homogeneous solution is obtained, and then carry out a stirring reaction under a nitrogen atmosphere. After washing, vacuum dry to obtain a white solid.

[0011] 3) Put the white solid into an aqueous sodium hydroxide solution and stir at room temperature for 72 hours. After the reaction is completed, separate the solid by centrifugation, and wash with deionized water to obtain the hydroxyl intermediate [ECD]OH. Put [ECD]OH into an aqueous solution of an organic acid and react at room temperature for 72 hours, centrifuge, wash with deionized water, and vacuum dry to obtain the final polyionic liquid.

[0012] In the above preparation method, in step 1), 1-vinylimidazole: bis(2-chloroethyl) ether = 1.25:1.

[0013] In the above preparation method, in step 1), the stirring reaction is carried out at 75 °C for 48 hours.

[0014] In the above preparation method, in step 2), the stirring reaction is carried out at 80 °C for 24 hours.

[0015] In the above preparation method, in step 3), the organic acid is glycolic acid, lactic acid or glacial acetic acid.

[0016] Application of an organic acid anion pair polyionic liquid in the synthesis of cyclic carbonates from epoxides by catalysis.

[0017] The above application is carried out as follows: A catalyst, carbon dioxide and an epoxide are mixed and reacted at a pressure of 0.2 - 1.0 MPa and a temperature of 80 - 120 °C for 6 - 14 hours; the catalyst is the organic acid anion pair ionic liquid described in claim 1.

[0018] In the above application, the addition amount of the catalyst is 0.14 g, and the addition amount of the epoxide is 3% - 8% of the mass of the catalyst.

[0019] In the above application, the epoxide is epichlorohydrin, propylene oxide, butylene oxide, 1,2-epoxyethylbenzene or epibromohydrin.

[0020] The beneficial effects of the present invention are as follows: The organic acid anion pair polyionic liquid is used as a catalyst in the cycloaddition reaction of epoxides and carbon dioxide to synthesize cyclic carbonates. Compared with traditional catalysts, the catalytic process of the present invention is simple, the reaction system does not require a solvent and a cocatalyst, the reaction conditions are mild, while ensuring the catalytic effect, the cost of the catalyst is greatly reduced, the yield of the cyclic carbonate is very high, and at the same time, the pollution of the environment by halogens is avoided. Description of the Drawings

[0021] Figure 1 It is the NMR spectrum of propylene carbonate obtained in Example 4.

[0022] Figure 2 It is the NMR spectrum of styrene carbonate obtained in Example 4.

[0023] Figure 3 It is the NMR spectrum of chloropropylene carbonate obtained in Example 4.

[0024] Figure 4 It is the NMR spectrum of butylene carbonate obtained in Example 4.

[0025] Figure 5 It is the NMR spectrum of bromopropylene carbonate obtained in Example 4. Detailed Embodiments

[0026] Example 1 Preparation of an organic acid anion pair polyionic liquid catalyst (I) Preparation of the organic acid anion pair polyionic liquid [ECD][GLY]

[0027] 1) Accurately weigh 1-vinylimidazole (0.0625 mol, 5.88 g) and dissolve it in 10 mL of acetonitrile. Slowly add bis(2-chloroethyl) ether (0.025 mol, 3.575 g) dropwise at 40 °C. After the addition is complete, stir and react at 75 °C for 48 hours under a nitrogen atmosphere. After the reaction is completed, add ether to the reaction solution to precipitate the ionic liquid [EEBVIM]Cl2, and wash it with ethyl acetate until the unreacted substrates are removed. Then place it in a vacuum drying oven at 50 °C and dry for 48 hours.

[0028] 2) Filter and remove the 0.1% TBC stabilizer contained in divinylbenzene (DVB) using a basic alumina column with a mesh size of 100 - 200. Subsequently, accurately weigh 1 g of the dried [EEBVIM]Cl2, 0.394 g of DVB, and 0.0195 g of azobisisobutyronitrile AIBN, and dissolve them in a mixed solution composed of absolute ethanol, ethyl acetate, and deionized water (5:2:1). Stir at room temperature until a homogeneous solution is obtained, and then stir and react at 80 °C for 24 hours under a nitrogen atmosphere to obtain a white solid. Wash it with deionized water, and place the white solid in a vacuum drying oven to dry.

[0029] 3) Accurately weigh 0.5 g of the white solid and place it in an aqueous sodium hydroxide solution (80 mL, 1 M), and stir at room temperature for 72 hours. After the reaction is completed, separate the solid by centrifugation and wash it with deionized water to obtain the hydroxyl intermediate [ECD]OH. Subsequently, place 0.5 g of [ECD]OH in an aqueous glycolic acid solution (1 M, 80 mL), stir at room temperature for 72 hours, centrifuge, wash with deionized water, and dry at 70 °C in a vacuum for 48 hours to obtain the final polyionic liquid [ECD][GLY]. The structural formula is as follows.

[0030]

[0031] (II) Preparation of polyionic liquid [ECD][LA] with organic acid anions

[0032] The method is the same as (I), replace glycolic acid with lactic acid to obtain the pure polyionic liquid [ECD][LA] with organic acid anions. The structural formula is as follows.

[0033]

[0034] (III) Preparation of polyionic liquid [ECD][AA] with organic acid anions

[0035] The method is the same as (I), replace glycolic acid with glacial acetic acid to obtain the pure polyionic liquid [ECD][AA] with organic acid anions. The structural formula is as follows.

[0036]

[0037] Example 2 Effect of Organic Acid Anions on the Cycloaddition Reaction of Epoxides Catalyzed by Poly(ionic liquid)

[0038] (I) Effect of Temperature on Reaction Yield

[0039] In a 50 mL high-pressure reactor, the catalyst [ECD][GLY] and epichlorohydrin were added, mixed, and 0.6 MPa CO2 was introduced. The reaction was carried out for 14 hours at the temperatures shown in Table 1. The amount of epichlorohydrin added was 30 mmol, and the amount of catalyst added was 0.14 g. After the reaction, the yield of cyclic carbonate was calculated, and the results are shown in Table 1.

[0040] Table 1

[0041] Temperature °C 80 90 100 110 120 Yield % 48.6 74.5 89.1 94.9 98.1

[0042] (II) Effect of CO2 Pressure on Reaction Yield

[0043] The method was the same as (I), the temperature was 120 °C, and the pressure was changed as shown in Table 2. The results are shown in Table 2.

[0044] Table 2

[0045] Pressure MPa 0.2 0.4 0.6 0.8 1.0 Yield % 91.3 96.1 98.1 98.3 98.4

[0046] (III) Effect of Catalyst Dosage on Reaction Yield

[0047] The method was the same as (I), the temperature was 120 °C, and the amount of catalyst added was changed as shown in Table 3. The results are shown in Table 3.

[0048] Table 3

[0049] Catalyst dosage g 0.06 0.08 0.1 0.12 0.14 Yield % 92.7 95.4 96.6 97.5 98.1

[0050] (IV) Effect of Reaction Time on Reaction Yield

[0051] The method was the same as (I), the temperature was 120 °C, and the reaction time was changed as shown in Table 4. The results are shown in Table 4

[0052] Table 4

[0053] Reaction time h 6 8 10 12 14 Yield % 72.1 82.5 90.2 95.7 98.1

[0054] In summary, for the cycloaddition reaction of epoxides catalyzed by poly(ionic liquid) with organic acid anions, it is preferred that in a 50 mL high-pressure reactor, the catalyst and epoxide are added, mixed, 0.6 MPa CO2 is introduced, and the reaction is carried out at 120 °C for 14 hours. The amount of epichlorohydrin is 30 mmol, and the amount of catalyst added is 0.14 g. The obtained product, propylene chlorocarbonate, was detected by NMR and was consistent with the theoretical value, proving that the pure target product, propylene chlorocarbonate, was obtained.

[0055] Example 3 Effect of Organic Acid Anions on the Cycloaddition Reaction of Epoxides Catalyzed by Poly(ionic liquid)

[0056] In a 50 mL high-pressure reactor, the catalyst (as shown in Table 5) and epichlorohydrin were added and mixed. Then, 0.6 MPa of CO2 was introduced, and the reaction was carried out at 120 °C for 14 hours. The amount of epichlorohydrin was 30 mmol, and the amount of catalyst added was 0.14 g. After the reaction, the yield of cyclic carbonate was calculated, and the results are shown in Table 5.

[0057] Table 5

[0058] Catalyst [ECD][GLY] [ECD][LA] [ECD][AA] Yield % 98.1 96 97.1

[0059] Example 4 Effect of Organic Acid Anions on the Cycloaddition Reaction of Different Epoxides Catalyzed by Poly(ionic liquid)

[0060] In a 50 mL high-pressure reactor, the catalyst [ECD][GLY] and epoxide (Table 6) were added and mixed. Then, 0.6 MPa of CO2 was introduced, and the reaction was carried out at 120 °C for 14 hours. The amount of epoxide added was 30 mmol, and the amount of catalyst added was 0.08 g - 0.22 g based on the mass of the epoxide. After the reaction, the yield of cyclic carbonate was calculated, and the results are shown in Table 6.

[0061] Table 6

[0062]

[0063]

[0064] Figure 1 is the NMR spectrum of propylene carbonate obtained in Example 5. Figure 2 is the NMR spectrum of styrene carbonate obtained in Example 5. Figure 3 is the NMR spectrum of chloropropylene carbonate obtained in Example 5. Figure 4 is the NMR spectrum of butene carbonate obtained in Example 5. Figure 5 is the NMR spectrum of bromopropylene carbonate obtained in Example 5. Figure 1 : 1 H NMR(300MHz,CDCl3):δ4.91(m,1H),4.58(q,1H),4.05(q,1H),1.50(d,3H); Figure 2 : 1 H NMR(300MHz,CDCl3):δ7.44(m,5H),5.70(t,1H),4.83(t,1H),4.37(q,1H); Figure 3 : 11H NMR (300 MHz, CDCl3): δ 5.00 (m, 1H), 4.55 (m, 1H), 4.40 (q, 1H), 3.76 (m, 2H); Figure 4 : 1 1H NMR (300 MHz, CDCl3) δ 4.60 (dd, 1H), 4.47 (t, 1H), 4.48 (m, 1H), 1.84 - 1.76 (m, 1H), 1.04 (dd, 3H); Figure 5 : 1 1H NMR (300 MHz, CDCl3): δ 4.97 (m, 1H), 4.61 (t, 1H), 4.44 (dd, 1H), 3.66 (m, 2H).

Claims

1. An organic acid anion pair polyionic liquid, characterized in that: The poly(ionic liquid) described above is composed of a bis-imidazole ring cation and an organic acid anion; wherein, R = CH3CHOHCOO - or OHCH2COO - or CH3COO - .

2. The preparation method of a polyionic liquid with an organic acid anion according to claim 1, characterized in that, The preparation method is as follows: 1) Weigh 1-vinylimidazole and dissolve it in acetonitrile. Slowly add bis(2-chloroethyl) ether dropwise at 40 °C. Stir and react under a nitrogen atmosphere. Wash with ethyl acetate to remove unreacted substrates, and then dry under vacuum to obtain the ionic liquid [EEBVIM]Cl2; 2) Filter the 0.1% TBC stabilizer contained in divinylbenzene (DVB) through a basic alumina column with a mesh size of 100 - 200. Then take [EEBVIM]Cl2, DVB, and azobisisobutyronitrile (AIBN), dissolve them in a mixed solvent, stir at room temperature until a homogeneous solution is obtained, and then stir and react under a nitrogen atmosphere. After washing, dry under vacuum to obtain a white solid. 3) Put the white solid into an aqueous sodium hydroxide solution and stir at room temperature for 72 hours. After the reaction, separate the solid by centrifugation and wash it with deionized water to obtain the hydroxy intermediate [ECD]OH. Put [ECD]OH into an aqueous solution of an organic acid and react at room temperature for 72 hours. Centrifuge, wash with deionized water, and dry under vacuum to obtain the final poly(ionic liquid).

3. The preparation method according to claim 2, characterized in that: In step 1), 1-vinylimidazole:bis(2-chloroethyl) ether = 1.25:

1.

4. The preparation method according to claim 2, characterized in that: In step 1), the stirring reaction is carried out by stirring at 75 °C for 48 hours.

5. The preparation method according to claim 2, characterized in that: In step 2), the stirring reaction is carried out by stirring at 80 °C for 24 hours.

6. The preparation method according to claim 2, characterized in that: In step 3), the organic acid is glycolic acid, lactic acid, or glacial acetic acid.

7. Use of an organic acid anion poly(ionic liquid) as described in claim 1 in the synthesis of cyclic carbonates from epoxides.

8. The application according to claim 7, characterized in that, The method is as follows: Mix the catalyst, carbon dioxide, and epoxide, and react at a pressure of 0.2 - 1.0 MPa and a temperature of 80 - 120 °C for 6 - 14 hours; the catalyst is the organic acid anion ionic liquid as described in claim 1.

9. The application according to claim 8, characterized in that: The addition amount of the catalyst is 0.14 g, and the addition amount of the epoxide is 3% - 8% of the mass of the catalyst.

10. The application according to claim 7, 8 or 9, characterized in that: The epoxide is epichlorohydrin, propylene oxide, epoxybutane, 1,2-epoxyethylbenzene, or epibromohydrin.

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