CN102702165A - A kind of NHC/ZnBr2 system catalyzes the method for preparing cyclic carbonate - Google Patents

Abstract

The invention discloses a method for preparing cyclic carbonates catalyzed by NHC/ _ZnBr2 system, using N,N'-(2,6-diisopropylphenyl)-imidazoline hydrochloride, potassium carbonate and bromide The NHC/ZnBr ₂ system composed of three zinc compounds was used as a catalyst to catalyze the cycloaddition synthesis of epoxide and carbon dioxide under the conditions of reaction pressure of 0.1MPa, reaction temperature of 80°C, reaction time of 24h, and reaction solvent of DMSO. of cyclic carbonates. The synthesis method has the characteristics of mild reaction conditions, high catalytic activity, single product, simple purification operation and the like.

Description

A kind of NHC/ZnBr2 system catalyzes the method for preparing cyclic carbonate

technical field

The invention relates to a method for preparing carbonate by cycloaddition of epoxide and carbon dioxide, especially a method for preparing cyclic carbonate by NHC/ _ZnBr2 system catalysis.

Background technique

Carbon dioxide (CO ₂ ) is one of the most widely distributed, abundant and cheapest carbon resources on the earth. It is estimated that there are about 10 ¹⁶ tons of carbon reserves in the form of CO ₂ and carbonate. In addition, _CO2 also has many advantages such as stable properties, non-toxic, non-corrosive, flame-retardant, and easy to handle. Using the limited and non-renewable petrochemical resources as a substitute for Cl synthesis to obtain useful compounds through chemical transformation has always been one of the green chemistry topics that has attracted much attention, and has important application value and theoretical research significance.

At present, the chemical utilization of _CO2 has begun to take shape, and nearly 110 million tons of _CO2 are chemically fixed every year. Urea is the largest product for fixing CO ₂ , consuming more than 70 million tons of CO ₂ per year; followed by inorganic carbonate, which reaches 30 million tons per year; the hydrogenation reduction of CO ₂ to synthesize CO ₂ has also reached 6 million tons. In addition, more than 20,000 tons of CO ₂ are used in the synthesis of pharmaceutical intermediates such as salicylic acid and propylene carbonate every year. Although the chemical conversion method of carbon dioxide has been applied in industrial production, it is not enough to solve the greenhouse effect caused by the increasingly serious excessive emission of carbon dioxide due to the limitation of production scale and single method. It is an urgent problem for chemists to study new CO ₂ chemical conversion methods, increase the products of CO ₂ chemical conversion, and increase the conversion and utilization scale of CO ₂ .

As a reaction intermediate, nitrogen heterocyclic carbene has very high reactivity, strong basicity and strong nucleophilicity, so it has a very broad application prospect in the field of catalysis. It has been reported in the literature that 1,5-diisopropyl-4, 5-Dimethyl but heterocyclic carbene is more basic than 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) and 1,8-diazabicyclo[5.4.0] Undecene-7 (DBU).

Contents of the invention

The object of the present invention is to provide a kind of NHC/ZnBr System catalyzed carbon dioxide and epoxide generation cycloaddition reaction to prepare the method for corresponding cyclic carbonate, general reaction formula of the present invention is:

R=CH ₃ CH ₂ , n-Bu, ClCH ₂ , BrCH ₂ , Ph, PhCH ₂ , PhOCH ₂ , PhCH ₂ OCH ₂ , PhCOOCH ₂

The present invention adopts following technical scheme:

A kind of NHC/ _ZnBr2 system catalyzes the method for preparing cyclic carbonate, uses N, N'-(2,6-diisopropylphenyl)-imidazoline hydrochloride, potassium carbonate and zinc bromide three kinds of compounds The composed NHC/ZnBr ₂ system is used as a catalyst to catalyze the cycloaddition of epoxide and carbon dioxide to synthesize the corresponding cyclic carbonic acid under the conditions of reaction pressure of 0.1MPa, reaction temperature of 80°C, reaction time of 24h, and reaction solvent of DMSO. ester.

Described method, described N, N '-(2,6-diisopropylphenyl)-imidazoline hydrochloride preparation method is as follows:

Described method, the structure of described epoxide is:

In the described method, the dosage of each compound in the NHC/ _ZnBr2 system is 2% of the epoxide, and the molar amounts of the three compounds are equal.

Description of drawings

Fig. 1 is the hydrogen spectrogram of compound 1; Fig. 2 is the hydrogen spectrogram of compound 2; Fig. 3 is the hydrogen spectrogram of compound 3;

Fig. 4 is the hydrogen spectrogram of compound C ₅ H ₈ O ₃ ; Fig. 5 is the carbon spectrogram of compound C ₅ H ₈ O ₃ ;

Figure 6 is the hydrogen spectrum of compound C ₇ H ₁₂ O ₃ ; Figure 7 is the carbon spectrum of compound C ₇ H ₁₂ O ₃ ;

Figure 8 is the hydrogen spectrum of compound C ₄ H ₅ ClO ₃ ; Figure 9 is the carbon spectrum of compound C ₄ H ₅ ClO ₃ ;

Figure 10 is the hydrogen spectrum of compound C ₄ H ₅ BrO ₃ ; Figure 11 is the carbon spectrum of compound C ₄ H ₅ BrO ₃ ;

Figure 12 is the hydrogen spectrum of compound C ₉ H ₈ O ₃ ; Figure 13 is the carbon spectrum of compound C ₉ H ₈ O ₃ ;

Figure 14 is the hydrogen spectrum of compound C ₁₀ H ₁₀ O ₃ ; Figure 15 is the carbon spectrum of compound C ₁₀ H ₁₀ O ₃ ;

Figure 16 is the hydrogen spectrum of compound C ₁₀ H ₁₀ O ₄ ; Figure 17 is the carbon spectrum of compound C ₁₀ H ₁₀ O ₄ ;

Figure 18 is the hydrogen spectrum of compound C ₁₁ H ₁₂ O ₄ ; Figure 19 is the carbon spectrum of compound C ₁₁ H ₁₂ O ₄ ;

Figure 20 is the hydrogen spectrum of compound C ₁₁ H ₁₀ O ₅ ; Figure 21 is the carbon spectrum of compound C ₁₁ H ₁₀ O ₅ ;

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments.

Example 1

The structure of the nitrogen heterocyclic carbene (NHC) ligand involved in the present invention is as follows:

The preparation method is as follows:

Synthesis of N,N'-(2,6-diisopropylphenyl)-ethylenediimine 1:

In a 100mL round bottom flask, add 2,6-diisopropylaniline (8.86g, 50mmol), 40% glyoxal (3.63g, 25mmol) and 40mL absolute ethanol, and react for 10min at room temperature, It was found that a large amount of solids were precipitated. After the reaction was continued to stir for 12 hours, it was directly suction filtered and dried under vacuum to obtain 9.32 g of the target product as a yellow solid, with a yield of 99%.

Referring to Figure 1, it is the hydrogen spectrum of compound 1, ¹ H NMR (400MHz, CDCl ₃ ): δ8.11 (s, 2H), 7.21-7.18 (m, 6H), 2.98-2.92 (m, 4H), 1.22 (d, J=6.8Hz, 24H).

Synthesis of N,N'-(2,6-diisopropylphenyl)-ethylenediamine 2:

In a 250mL round bottom flask, add Compound 1 (7.53g, 20mmol) and 150mL of absolute ethanol, then add sodium borohydride (3.70g, 100mmol), place the flask in an oil bath, and adjust the temperature of the oil bath to 80°C , plug in the condenser, stop the reaction after reflux for 8h, the system changes from a yellow transparent solution to a supersaturated solution with a large amount of white solids, cool to room temperature, add a large amount of deionized water, and extract with dichloromethane (3 × 20mL) , the lower organic phase was collected, dried over anhydrous magnesium sulfate, and filtered to obtain a colorless and transparent clear solution. After rotary evaporation, 7.08 g of the target product was obtained as a white solid, with a yield of 93%.

Referring to Figure 2, it is the hydrogen spectrum of compound 2, ¹ H NMR (400MHz, CDCl ₃ ): δ7.16-7.07 (m, 6H), 3.42-3.36 (m, 6H), 3.18 (s, 4H), 1.28 (d, J=6.8Hz, 24H).

Synthesis of N, N'-(2,6-diisopropylphenyl)-imidazoline hydrochloride 3:

In a 50mL round-bottomed flask, add compound 2 (3.81g, 10mmol), ammonium chloride (0.53g, 10mmol) and 20mL triethyl orthoformate, and react in an oil bath at 130°C for 12h to stop the reaction and cool to room temperature After that, it was filtered with suction, washed with ether, and dried under vacuum to obtain 3.63 g of the target product as a white solid, with a yield of 85%.

Referring to Figure 3, it is the hydrogen spectrum of compound 3, which is the nitrogen heterocyclic carbene (NHC) ligand, ¹ H NMR (400MHz, D ₂ O): δ7.49(t, J=8.0Hz, 2H), 7.36(d , J=4.0Hz, 4H), 4.49(s, 4H), 3.04-2.97(m, 4H), 1.28(d, J=3.4Hz, 12H), 1.15(d, J=3.4Hz, 12H).

Example 2

NHC/ZnBr ₂ system catalyzes carbon dioxide and epoxide (1,2-epoxide n-butane) to generate cycloaddition reaction to prepare the method for corresponding cyclic carbonate, chemical reaction formula is:

experiment procedure

Weigh 2mol% (0.02:1 equivalent ratio of NHC to epoxide) of NHC ligand (0.15g, 0.35mmol), K ₂ CO ₃ (0.048g, 0.35mmol), ZnBr ₂ (0.079 g, 0.35mmol) is placed in a dry 50mL flask, a stirring bar is added, a rubber stopper is plugged to seal, then the flask is placed on a vacuum line to evacuate, and then a balloon filled with high-purity carbon dioxide is inserted on the rubber stopper. Inject 10ml of anhydrous and oxygen-free DMSO into the flask with a syringe, control the pressure at 1atm, then inject 1,2-epoxybutane (1.5mL, 17.5mmol) into the flask, and react in an oil bath at 80°C for 24h to stop the reaction. Cool to room temperature, add 200mL of deionized water, extract with dichloromethane (3 × 20mL), dry over anhydrous magnesium sulfate, then obtain the crude product by rotary evaporation of the filtrate obtained by filtration, and purify by column chromatography (eluent : dichloromethane) obtained yellow liquid is the target product, yield: 97%.

Yellow liquid, molecular formula C ₅ H ₈ O ₃

Referring to Figure 4, it is the hydrogen spectrum of compound C ₅ H ₈ O ₃ , ¹ H NMR (400MHz, CDCl ₃ ): δ4.69-4.62 (m, 1H), 4.52 (t, J=8.0Hz, 1H) , 4.08(t, J=7.6Hz, 1H), 1.87-1.68(m, 2H), 1.02(t, J=7.6Hz, 3H). Referring to Figure 5, the carbon spectrum of compound C ₅ H ₈ O ₃ , ¹³ C NMR (100MHz, CDCl ₃ ): δ155.1 (C=O), 78.0, 69.0, 26.9, 8.5. IR: 1799cm ^-1 (vCO ).

Example 3

NHC/ZnBr ₂ system catalyzes carbon dioxide and epoxide (1,2-epoxy n-hexane) to produce the cycloaddition reaction to prepare the method for corresponding cyclic carbonate, chemical reaction formula

experiment procedure

Weigh 2mol% NHC ligand (0.15g, 0.35mmol), K ₂ CO ₃ (0.048g, 0.35mmol), ZnBr ₂ (0.079g, 0.35mmol) in a dry 50mL flask, add and stir Plug the rubber stopper to seal it, then place the flask on the vacuum line to evacuate, then insert a balloon filled with high-purity carbon dioxide on the rubber stopper, inject 10ml of anhydrous and oxygen-free DMSO into the flask with a syringe, and then Inject 1,2-epoxy-n-hexane (2.1 mL, 17.5 mmol) into the flask, and react in an oil bath at 80° C. for 24 h to stop the reaction. Cool to room temperature, add 200mL of deionized water, extract with dichloromethane (3 × 20mL), dry over anhydrous magnesium sulfate, then obtain the crude product by rotary evaporation of the filtrate obtained by filtration, and purify by column chromatography (eluent : dichloromethane) obtained yellow liquid is the target product, yield: 96%.

Yellow liquid, molecular formula C ₇ H ₁₂ O ₃

Referring to Figure 6, the hydrogen spectrum of compound C ₇ H ₁₂ O ₃ , ¹ H NMR (400MHz, CDCl ₃ ): δ4.72-4.65 (m, 1H), 4.51 (t, J=8.0Hz, 1H), 4.05 (t, J = 8.0 Hz, 1H), 1.82-1.61 (m, 2H), 1.46-1.27 (m, 4H), 0.89 (t, J = 6.8 Hz, 3H).

Referring to Figure 7, the carbon spectrum of compound C ₇ H ₁₂ O ₃ , ¹³ C NMR (100MHz, CDCl ₃ ): δ155.0 (C=O), 69.3, 53.4, 33.4, 26.3, 22.1, 13.7. IR: 1790cm ^-1 (vCO).

Example 4

NHC/ _ZnBr2 system catalyzes carbon dioxide and epoxide (epichlorohydrin) generation cycloaddition reaction to prepare the method for corresponding cyclic carbonate, chemical reaction formula

experiment procedure

Weigh 2mol% NHC ligand (0.15g, 0.35mmol), K ₂ CO ₃ (0.048g, 0.35mmol), ZnBr ₂ (0.079g, 0.35mmol) in a dry 50mL flask, add and stir Plug the rubber stopper to seal it, then place the flask on the vacuum line to evacuate, then insert a balloon filled with high-purity carbon dioxide on the rubber stopper, inject 10ml of anhydrous and oxygen-free DMSO into the flask with a syringe, and then Inject epichlorohydrin (1.4 mL, 17.5 mmol) into the flask, and react in an oil bath at 80° C. for 24 h to stop the reaction. Cool to room temperature, add 200mL of deionized water, extract with dichloromethane (3 × 20mL), dry over anhydrous magnesium sulfate, then obtain the crude product by rotary evaporation of the filtrate obtained by filtration, and purify by column chromatography (eluent : dichloromethane) obtained yellow liquid is the target product, yield: 90%.

Yellow liquid, molecular formula C ₄ H ₅ ClO ₃

Referring to Figure 8, the hydrogen spectrum of compound C ₄ H ₅ ClO ₃ , ¹ H NMR (400MHz, CDCl ₃ ): δ4.99-4.93 (m, 1H), 4.59 (app.t, J=8.4Hz, 1H) , 4.41(dd, J=6.0Hz, J=8.8Hz, 1H), 3.78(dd, J=12.0Hz, J=5.6Hz, 1H), 3.73(dd, J=12.0Hz, J=4.0Hz, 1H ).

Referring to Figure 9, the carbon spectrum of compound C ₄ H ₅ ClO ₃ , ¹³ C NMR (100MHz, CDCl ₃ ): δ154.0 (C=O), 74.2, 66.9, 43.5. IR: 1790cm ^-1 (vCO).

Example 5

NHC/ _ZnBr2 system catalyzes carbon dioxide and epoxide (epibromohydrin) cycloaddition reaction to prepare the method for corresponding cyclic carbonate ester, chemical reaction formula

experiment procedure

Weigh 2mol% NHC ligand (0.15g, 0.35mmol), K ₂ CO ₃ (0.048g, 0.35mmol), ZnBr ₂ (0.079g, 0.35mmol) in a dry 50mL flask, add and stir Plug the rubber stopper to seal it, then place the flask on the vacuum line to evacuate, then insert a balloon filled with high-purity carbon dioxide on the rubber stopper, inject 10ml of anhydrous and oxygen-free DMSO into the flask with a syringe, and then Inject epibromopropane (1.5 mL, 17.5 mmol) into the flask, and react in an oil bath at 80° C. for 24 h to stop the reaction. Cool to room temperature, add 200mL of deionized water, extract with dichloromethane (3 × 20mL), dry over anhydrous magnesium sulfate, then obtain the crude product by rotary evaporation of the filtrate obtained by filtration, and purify by column chromatography (eluent : dichloromethane) obtained yellow liquid is the target product, yield: 92%.

Yellow liquid, molecular formula C ₄ H ₅ BrO ₃

Referring to Figure 10, the hydrogen spectrum of compound C ₄ H ₅ BrO ₃ , ¹ H NMR (400MHz, CDCl ₃ ): δ4.97-4.90 (m, 1H), 4.60 (app.t, J=8.4Hz, 1H) , 4.36 (dd, J=6.0Hz, J=9.0Hz, 1H), 3.61-3.52(m, 2H). Referring to Figure 11, the carbon spectrum of compound C ₄ H ₅ BrO ₃ , ¹³ C NMR (100MHz, CDCl ₃ ): δ154.2 (C=O), 73.9, 68.0, 31.7. IR: 1794cm ^-1 (vCO).

Example 6

NHC/ _ZnBr2 system catalyzes carbon dioxide and epoxide (phenyl oxirane) cycloaddition reaction to prepare the method for corresponding cyclic carbonate ester, chemical reaction formula

experiment procedure

Weigh 2mol% NHC ligand (0.15g, 0.35mmol), K ₂ CO ₃ (0.048g, 0.35mmol), ZnBr ₂ (0.079g, 0.35mmol) in a dry 50mL flask, add and stir Plug the rubber stopper to seal it, then place the flask on the vacuum line to evacuate, then insert a balloon filled with high-purity carbon dioxide on the rubber stopper, inject 10ml of anhydrous and oxygen-free DMSO into the flask with a syringe, and then Inject phenyloxirane (2.0 mL, 17.5 mmol) into the flask, and react in an oil bath at 80° C. for 24 h to stop the reaction. Cool to room temperature, add 200mL of deionized water, extract with dichloromethane (3 × 20mL), dry over anhydrous magnesium sulfate, then obtain the crude product by rotary evaporation of the filtrate obtained by filtration, and purify by column chromatography (eluent : dichloromethane) obtained white solid is the target product, yield: 95%.

White solid, molecular formula C ₉ H ₈ O ₃

Referring to Figure 12, the hydrogen spectrum of compound C ₉ H ₈ O ₃ , ¹ H NMR (400MHz, CDCl ₃ ): δ7.47-7.35 (m, 5H), 5.68 (t, J=8.0Hz, 1H), 4.80 (t, J=8.4Hz, 1H), 4.35 (t, J=8.4Hz, 1H). Referring to Figure 13, the carbon spectrum of compound C ₉ H ₈ O ₃ , ¹³ C NMR (100MHz, CDCl ₃ ): δ154 .8 (C=O), 135.8, 129.7, 129.2, 125.8, 77.9, 71.1.IR: 1775cm ^-1 (vCO).

Example 7

NHC/ _ZnBr2 system catalyzes carbon dioxide and epoxide (benzyl oxirane) cycloaddition reaction to prepare the method for corresponding cyclic carbonate ester, chemical reaction formula

experiment procedure

Weigh 2mol% NHC ligand (0.15g, 0.35mmol), K ₂ CO ₃ (0.048g, 0.35mmol), ZnBr ₂ (0.079g, 0.35mmol) in a dry 50mL flask, add and stir Plug the rubber stopper to seal it, then place the flask on the vacuum line to evacuate, then insert a balloon filled with high-purity carbon dioxide on the rubber stopper, inject 10ml of anhydrous and oxygen-free DMSO into the flask with a syringe, and then Inject benzyl oxirane (2.3 mL, 17.5 mmol) into the flask, and react in an oil bath at 80° C. for 24 h to stop the reaction. Cool to room temperature, add 200mL of deionized water, extract with dichloromethane (3 × 20mL), dry over anhydrous magnesium sulfate, then obtain the crude product by rotary evaporation of the filtrate obtained by filtration, and purify by column chromatography (eluent : dichloromethane) obtained yellow liquid is the target product, yield: 96%.

Yellow liquid, molecular formula C ₁₀ H ₁₀ O ₃

Referring to Figure 14, the hydrogen spectrum of compound C ₁₀ H ₁₀ O ₃ , ¹ H NMR (400MHz, CDCl ₃ ): δ7.36-7.21(m, 5H), 4.96-4.89(m, 1H), 4.44(t, J=8.0Hz, 1H), 4.17(t, J=7.2Hz, 1H), 3.15(dd, J=14.0Hz, J=6.4Hz, 1H), 2.99(dd, J=14.2Hz, J=6.4Hz , 1H). Referring to Figure 15, the carbon spectrum of compound C ₁₀ H ₁₀ O ₃ , ¹³ C NMR (100MHz, CDCl ₃ ): δ154.8 (C=O), 133.8, 129.3, 128.9, 127.5, 76.7, 68.4 , 39.5.IR: 1791cm ^-1 (vCO).

Example 8

NHC/ _ZnBr2 system catalyzes carbon dioxide and epoxide (phenoxy propylene oxide) cycloaddition reaction to prepare the method for corresponding cyclic carbonate ester, chemical reaction formula

experiment procedure

Weigh 2mol% NHC ligand (0.15g, 0.35mmol), K ₂ CO ₃ (0.048g, 0.35mmol), ZnBr ₂ (0.079g, 0.35mmol) in a dry 50mL flask, add and stir Plug the rubber stopper to seal it, then place the flask on the vacuum line to evacuate, then insert a balloon filled with high-purity carbon dioxide on the rubber stopper, inject 10ml of anhydrous and oxygen-free DMSO into the flask with a syringe, and then Phenoxypropylene oxide (2.3 mL, 17.5 mmol) was injected into the flask, and the reaction was stopped in an oil bath at 80° C. for 24 h. Cool to room temperature, add 200mL of deionized water, extract with dichloromethane (3 × 20mL), dry over anhydrous magnesium sulfate, then obtain the crude product by rotary evaporation of the filtrate obtained by filtration, and purify by column chromatography (eluent : dichloromethane) obtained white solid is the target product, yield: 98%.

White solid, molecular formula C ₁₀ H ₁₀ O ₄

Referring to Figure 16, the hydrogen spectrum of compound C ₁₀ H ₁₀ O ₄ , ¹ H NMR (400MHz, CDCl ₃ ): δ7.31(t, J=7.6Hz, 2H), 7.02(t, J=7.2Hz, 1H ), 6.91(d, J=8.4Hz, 2H), 5.06-5.00(m, 1H), 4.62(t, J=8.8Hz, 1H), 4.54(dd, J=8.4Hz, J=6.0Hz, 1H ), 4.24(dd, J=10.0Hz, J=4.0Hz, 1H), 4.15(dd, J=10.4Hz, J=3.2Hz, 1H). Referring to Figure 17, the carbon spectrum of compound C ₁₀ H ₁₀ O ₁ Figure, ¹³ C NMR (100MHz, CDCl ₃ ): δ157.7, 154.6 (C=O), 129.7, 121.9, 114.5, 74.1, 66.8, 66.2. IR: 1803cm ^-1 (vCO).

Example 9

NHC/ _ZnBr2 system catalyzes carbon dioxide and epoxide (benzyloxy propylene oxide) cycloaddition reaction to prepare the method for corresponding cyclic carbonate ester, chemical reaction formula

experiment procedure

Weigh 2mol% NHC ligand (0.15g, 0.35mmol), K ₂ CO ₃ (0.048g, 0.35mmol), ZnBr ₂ (0.079g, 0.35mmol) in a dry 50mL flask, add and stir Plug the rubber stopper to seal it, then place the flask on the vacuum line to evacuate, then insert a balloon filled with high-purity carbon dioxide on the rubber stopper, inject 10ml of anhydrous and oxygen-free DMSO into the flask with a syringe, and then Inject benzyloxypropylene oxide (2.6 mL, 17.5 mmol) into the flask, and react in an oil bath at 80° C. for 24 h to stop the reaction. Cool to room temperature, add 200mL of deionized water, extract with dichloromethane (3 × 20mL), dry over anhydrous magnesium sulfate, then obtain the crude product by rotary evaporation of the filtrate obtained by filtration, and purify by column chromatography (eluent : dichloromethane) obtained yellow liquid is the target product, yield: 95%.

Yellow liquid, molecular formula C ₁₁ H ₁₂ O ₄

Referring to Figure 18, the hydrogen spectrum of compound C ₁₁ H ₁₂ O ₄ , ¹ H NMR (400 MHz, CDCl ₃ ): δ7.39-7.30 (m, 5H), 4.85-4.79 (m, 1H), 4.60 (dd, J=22.8Hz, J=12.0Hz, 2H), 4.49(app.t, J=8.4Hz, 1H), 4.39(dd, J=8.4Hz, J=6.0Hz, 1H), 3.71(dd, J= 10.8Hz, J=3.6Hz, 1H), 3.62 (dd, J=10.8Hz, J=3.6Hz, 1H). Referring to Figure 19, the carbon spectrum of compound C ₁₁ H ₁₂ O ₄ , ¹³ C NMR (100MHz, CDCl ₃ ): δ154.8 (C=O), 137.0, 128.6, 128.1, 127.7, 74.9, 73.7, 68.8, 66.3. IR: 1790cm ^-1 (vCO).

Example 10

NHC/ _ZnBr2 system catalyzes carbon dioxide and epoxide (benzoic acid group epoxy propylene) to produce the cycloaddition reaction to prepare the method for corresponding cyclic carbonate ester, chemical reaction formula

experiment procedure

Weigh 2mol% NHC ligand (0.15g, 0.35mmol), K ₂ CO ₃ (0.048g, 0.35mmol), ZnBr ₂ (0.079g, 0.35mmol) in a dry 50mL flask, add and stir Plug the rubber stopper to seal it, then place the flask on the vacuum line to evacuate, then insert a balloon filled with high-purity carbon dioxide on the rubber stopper, inject 10ml of anhydrous and oxygen-free DMSO into the flask with a syringe, and then Inject benzoyloxypropylene (2.8 mL, 17.5 mmol) into the flask, and react in an oil bath at 80° C. for 24 h to stop the reaction. Cool to room temperature, add 200mL of deionized water, extract with dichloromethane (3 × 20mL), dry over anhydrous magnesium sulfate, then obtain the crude product by rotary evaporation of the filtrate obtained by filtration, and purify by column chromatography (eluent : dichloromethane) obtained yellow liquid is the target product, yield: 97%.

Yellow liquid, molecular formula: C ₁₁ H ₁₀ O ₅

Referring to Figure 20, the hydrogen spectrum of compound C ₁₁ H ₁₀ O ₅ , ¹ H NMR (400MHz, CDCl ₃ ): δ8.02(d, J=8.0Hz, 2H), 7.60(t, J=7.2Hz, 1H ), 7.47(t, J=7.6Hz, 2H), 5.09-5.03(m, 1H), 4.65-4.57(m, 2H), 4.51(dd, J=12.8Hz, J=4.0Hz, 1H), 4.43 (dd, J=8.4Hz, J=5.6Hz, 1H). Referring to Figure 21, the carbon spectrum of compound C ₁₁ H ₁₀ O ₅ , ¹³ C NMR (100MHz, CDCl ₃ ): δ165.9 (C=O) , 154.4 (C=O), 133.7, 129.8, 128.6, 128.4, 73.8, 66.0, 63.6. IR: 1793cm ^-1 (vCO).

It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should belong to the protection scope of the appended claims of the present invention.

Claims (4)

1. NHC/ZnBr ₂The method of system catalytic preparation of cyclic carbonic ether is characterized in that, uses N, N '-(2, the 6-diisopropyl phenyl)-imidazoline salt hydrochlorate, the NHC/ZnBr that three kinds of compounds of salt of wormwood and zinc bromide are formed ₂System is 0.1MPa as catalyzer in reaction pressure, and temperature of reaction is 80 ℃, and the reaction times is 24h, and reaction solvent is catalysis epoxidation thing and the synthetic corresponding cyclic carbonic ether of carbonic acid gas cycloaddition under the condition of DMSO.

2. method according to claim 1 is characterized in that, said N, and N '-(2, the 6-diisopropyl phenyl)-preparation method is following for the imidazoline salt hydrochlorate:

3. method according to claim 1 is characterized in that, the structure of said epoxide is:

4. method according to claim 1 is characterized in that, said NHC/ZnBr ₂The consumption of each compound in the system is 2% of an epoxide, and the molar weight of three kinds of compounds equates.

Images