阅读说明：本技术 胺盐类离子液体高效催化合成环状碳酸酯的方法 (Method for efficiently synthesizing cyclic carbonate by using amine salt ionic liquid as catalyst ) 是由 张敬来 王丽 任铁钢 刘昉 于 2020-11-05 设计创作，主要内容包括：本发明提供了一种胺盐类离子液体催化合成环状碳酸酯的方法,其以二氧化碳和环氧化合物为底物,在反应压力为0.1-0.5MPa,温度30℃-60℃,反应时间1-10小时条件下制备环状碳酸酯的。该反应所使用的催化剂是酸碱反应的产物---一种胺盐类离子液体,该离子液体备受青睐主要是因为它具有易于制备、原料成本低廉、绿色环保、催化剂活性高等优点。需要指出的是,在50℃相当温和的条件下,加入少量的离子液体催化剂,环状碳酸酯的收率可达99%以上。(The invention provides a method for synthesizing cyclic carbonate ester by catalyzing amine salt ionic liquid, which takes carbon dioxide and epoxy compound as substrates and prepares the cyclic carbonate ester under the conditions that the reaction pressure is 0.1-0.5MPa, the temperature is 30-60 ℃ and the reaction time is 1-10 hours. The catalyst used in the reaction is an acid-base reaction product, namely an amine salt ionic liquid, and the ionic liquid is favored mainly because of the advantages of easy preparation, low cost of raw materials, environmental protection, high catalyst activity and the like. It is noted that under the rather mild condition of 50 ℃, the yield of the cyclic carbonate can reach more than 99% by adding a small amount of ionic liquid catalyst.)

1. An amine salt ionic liquid, which is characterized in that the structure of the amine salt ionic liquid is shown as any one of the following:

、。

2. the method for synthesizing cyclic carbonate ester catalyzed by amine salt ionic liquid as claimed in claim 1, wherein the amine salt ionic liquid and the epoxy compound are mixed according to the ratio of (5-15): mixing 100 mol ratio in a reaction kettle, introducing carbon dioxide to make the pressure of the reaction kettle be 0.1-0.5MPa, then reacting for 1-10 hours at constant temperature and constant pressure under the condition of reaction temperature of 30-60 ℃, and carrying out post-treatment after the reaction is finished.

3. The method for catalytically synthesizing cyclic carbonate ester according to claim 2, wherein the epoxy compound has the structure of 。

4. The method for catalytically synthesizing cyclic carbonate ester according to claim 2 or 3, wherein the molar ratio of the amine salt ionic liquid to the epoxy compound is 15: 100.

5. The method for catalytically synthesizing cyclic carbonate ester according to claim 4, wherein the reaction temperature is 50-60 ℃.

Technical Field

The invention belongs to the technical field of cyclic carbonate synthesis, and particularly relates to a method for efficiently catalyzing and synthesizing cyclic carbonate through cycloaddition reaction by using a novel amine salt ionic liquid as a catalyst.

Background

CO₂The excessive emission causes greenhouse effect, which causes a series of environmental problems such as global warming, sea level rising, climate abnormality, etc. But at the same time, it is a cheap, rich, nontoxic and sustainable C1 resource. Currently, there are over one hundred million tons of CO per year₂The products are converted and utilized, and the mature products comprise urea, salicylic acid, methanol, cyclic carbonate and polycarbonate. This is of great significance to the improvement of environment and from the perspective of green sustainability. In a large number of CO₂In the conversion utilization pathway, CO₂The cycloaddition reaction with epoxy compounds is the most efficient and widely used process, on the one hand it is characterized by atom economy, negligible by-products and on the other hand the cyclic carbonates produced are widely used. It is an important intermediate for the production of polymers and fine chemicals. In addition, the cyclic carbonates can also be used directly as good polar solvents in organic synthesis or as liquid electrolytes in lithium batteries.

Because cyclic carbonates have great market demand and wide application prospects, catalysts with higher activity need to be explored to improve the yield of cyclic carbonates. Various homogeneous and heterogeneous catalysts have been reported for CO₂And epoxy compounds, including MOFs, metal-salen complexes, and metalloporphyrin compounds. The amine salt ionic liquid shows good reaction activity under mild reaction conditions, but has high toxicity, complex synthesis process and higher cost, and the amine salt ionic liquid is distinguished from a plurality of catalysts by unique advantages. In recent decades, various ionic liquids have been developed, and functionalized ionic liquids, dicationic ionic liquids, bifunctional ionic liquids, etc. are numerous, but in the absence of metal promoters or organic solvents, general ionic liquids may still have one or more disadvantages of difficult synthesis, poor environmental protection, poor economy, and low catalytic activity. Therefore, the method explores high efficiency which is nontoxic and harmless, has low cost and high catalytic activity under mild conditionsIonic liquids are highly desirable.

Disclosure of Invention

Aiming at the problems of harsh reaction conditions, complex catalyst synthesis, low catalyst activity, insufficient environmental protection, high cost and the like of the existing cyclic carbonate synthesis method, the invention explores a novel method for efficiently catalyzing and synthesizing the cyclic carbonate through cycloaddition reaction by taking novel amine salt ionic liquid as a catalyst under mild conditions.

The invention provides an amine salt ionic liquid, which has a structure shown in any one of the following formulas:

the invention also provides a method for synthesizing cyclic carbonate by utilizing the amine salt ionic liquid, which comprises the following steps: mixing the amine salt ionic liquid and the epoxy compound according to the ratio of (5-15): mixing 100 mol ratio in a reaction kettle, keeping the reaction kettle in a closed state, introducing carbon dioxide to ensure that the pressure of the reaction kettle is 0.1-0.5MPa, then reacting for 1-10 hours at constant temperature and constant pressure under the condition of reaction temperature of 30-60 ℃, adding ethyl acetate after the reaction is finished, dissolving the product in ethyl acetate, separating out the catalyst, and analyzing the product by gas chromatography to obtain the product yield.

As a further optimization of the present invention, the epoxy compound may have a structure of

Further preferably, the molar ratio of the amine salt ionic liquid to the epoxy compound is 15: 100.

Further preferably, the reaction temperature is 50-60 ℃.

The method takes carbon dioxide and epoxy compound as reactants, and prepares corresponding cyclic carbonate through cycloaddition reaction under the conditions that the reaction pressure is 0.1-0.5MPa, the temperature is 30-60 ℃ and the reaction time is 1-10 hours, and the used catalyst is amine salt ionic liquid which is a product of acid-base reaction. Compared with the prior art, the invention has the following beneficial effects:

the method is worthy of being called by the innovation of the catalyst, is a novel amine salt ionic liquid prepared by acid-base reaction, has simpler synthesis steps, lower raw material cost and high catalytic activity, still has good activity after being repeatedly utilized for five times, and is an ideal catalyst. When the reaction temperature is 50 ℃, an unexpected yield (99%) of cyclic carbonate can be achieved by adding only a very small amount of ionic liquid catalyst. From the above description, it can be seen that the method of the present invention has great application potential, great value and longing.

Drawings

FIG. 1 is [ BETMA ] prepared in example 1⁺][^-O₂EEPZ⁺][Br^-]Nuclear magnetic resonance hydrogen spectrum of the catalyst;

FIG. 2 is [ BETMA ] prepared in example 1⁺][^-O₂EEPZ⁺][Br^-]Nuclear magnetic resonance carbon spectrum of the catalyst; as can be seen from fig. 1 and 2, the synthesized catalyst is the target catalyst.

Detailed Description

The method for synthesizing the amine salt ionic liquid catalyst used in the present invention is illustrated by the following examples, which are only for illustrating the present invention and are not intended to limit the present invention.

Example 1 preparation of an amine salt-based Ionic liquid

Putting 10mmol of carboxyethyl ethyl pyrazole bromide (CEEPzBr) and 10mmol of benzyl trimethyl ammonium hydroxide into a 50ml volumetric flask, adding 5ml of methanol as a solvent, reacting for 12h at normal temperature, and performing rotary evaporation (removing the methanol solvent), washing (washing with 20ml of ethyl acetate for three times) and drying (drying in vacuum at 60 ℃ for 4h) after the reaction is finished to obtain pure ionic liquid [ BETMA ]⁺][^-O₂EEPZ⁺][Br^-]The NMR spectrum is shown in FIG. 1, the NMR spectrum is shown in FIG. 2, and the structure is shown inShown below:

with reference to the above procedure, benzyltrimethylammonium hydroxide was replaced with 1, 8-diazabicycloundecen-7-ene (DBU) to give an ionic liquid [ DBUH⁺][^-O₂EEPZ⁺][Br^-](ii) a Replacing bromocarboxyethyl pyrazole salt (CEEPzBr) with 2,2, 2-Trifluoroethanol (TFE) to obtain ionic liquid [ BETMA⁺][TFE^-](ii) a The structural formulas of the two ionic liquids are respectively as follows:

example 2

Taking [ BETMA ] in example 1⁺][^-O₂EEPZ⁺][Br^-]Adding 0.75mmol of catalyst into a 50ml clean high-pressure reaction kettle, adding 5mmol of epichlorohydrin into the reaction kettle, keeping the reaction kettle in a closed state, and slowly introducing CO into the reaction kettle₂The gas removes the air in the reaction kettle, and finally the CO is removed₂The pressure is stabilized at 0.1MPa, the reaction is carried out for 6h at 50 ℃, ethyl acetate is added after the reaction is finished, the product is dissolved in the ethyl acetate, the catalyst is separated out, and the product is analyzed by gas chromatography, the yield of the product propylene carbonate is 99.3 percent, and the selectivity is more than 99 percent.

Example 3

The specific experimental procedure and detection method are the same as those in example 2, except that the catalyst used is [ DBUH ]⁺][^-O₂EEPZ⁺][Br^-]The product yield was found to be 97.5% with a selectivity > 99%.

Example 4

The specific experimental procedure and detection method are the same as those in example 2, except that the catalyst used is [ BETMA⁺][TFE^-]And the product yield was found to be 69.5%The selectivity is more than 99 percent.

Example 5

The specific experimental process and detection method are the same as example 2, except that the molar content of the catalyst in the epichlorohydrin is 5 mol%, the measured product yield is 74.2%, and the selectivity is more than 99%.

Example 6

The specific experimental process and detection method are the same as example 2, except that the molar content of the catalyst in the epichlorohydrin is 7 mol%, the measured product yield is 85.2%, and the selectivity is more than 99%.

Example 7

The specific experimental process and detection method are the same as example 2, except that the molar content of the catalyst in the epichlorohydrin is 10 mol%, the measured product yield is 92.8%, and the selectivity is more than 99%.

Example 8

The specific experimental process and detection method are the same as example 2, except that the molar content of the catalyst in the epichlorohydrin is 12 mol%, the measured product yield is 96.1%, and the selectivity is more than 99%.

Example 9

The specific experimental process and detection method are the same as example 2, except that the reaction time is 1h, the product yield is 57.9%, and the selectivity is more than 99%.

Example 10

The specific experimental process and detection method are the same as example 2, except that the reaction time is 2h, the product yield is 74.8%, and the selectivity is more than 99%.

Example 11

The specific experimental process and detection method are the same as example 2, except that the reaction time is 3h, the product yield is 84.8%, and the selectivity is more than 99%.

Example 12

The specific experimental process and detection method are the same as example 2, except that the reaction time is 4h, the product yield is 90.1%, and the selectivity is more than 99%.

Example 13

The specific experimental process and detection method are the same as example 2, except that the reaction time is 5h, the product yield is 95.4%, and the selectivity is more than 99%.

Example 14

The specific experimental procedure and detection method are the same as example 2, except that the epoxy compound used is propylene oxide, the product yield is 48.1%, and the selectivity is more than 99%.

Example 15

The specific experimental process and detection method are the same as example 2, except that the epoxy compound used is epoxypropanol, the yield of the product measured by a weighing method is 57.7%, and the selectivity is more than 99%.

And (3) weighing method: dissolving the product after the reaction with methanol, taking out from the reaction kettle, and carrying out rotary evaporation to obtain the product with mass m, wherein the mass of the used catalyst is m1, the mass of the substrate is m2, and the yield is calculated by

The reaction equation of the experiment is as follows:

example 16

The specific experimental process and detection method are the same as those in example 2, except that the epoxy compound used is phenyl glycidyl ether, the reaction temperature is 60 ℃, and the CO pressure is 0.5MPa₂The reaction time is 10h, the yield of the product measured by a weighing method is 72.7 percent, and the selectivity is more than 99 percent.

The reaction equation of the experiment is as follows:

example 17

The specific experimental process and detection method are the same as those in example 2, except that the epoxy compound used is styrene oxide, the reaction temperature is 60 ℃, and the CO pressure is 0.5MPa₂Reaction time is 10h, measureThe yield of the obtained product is 85.2 percent, and the selectivity is more than 99 percent.

The reaction equation of the experiment is as follows:

example 18

The specific experimental procedure and detection method were the same as in example 17 except that the epoxy compound used was allyl glycidyl ether, and the product yield was 91.9% with a selectivity of > 99%.

The reaction equation of the experiment is as follows:

example 19

The procedure and test procedure were as in example 17 except that the epoxy compound used was epoxycyclohexane, and the product yield was 20.5% with a selectivity of > 99%.

The reaction equation of the experiment is as follows:

examples 21 to 25

The specific experimental process and detection method are the same as those in example 2, and the only difference is that the catalyst used is [ BETMA ] recovered in example 2⁺][^-O₂EEPZ⁺][Br^-]The catalyst was subjected to 5 cycles of recovery under the same conditions, and the results are shown in Table 1.

TABLE 1, examples 21-25 catalyst recovery Using the catalytic results

As can be seen from Table 1, [ BETMA⁺][^-O₂EEPZ⁺][Br^-]After the catalyst is recycled for 2 times, the catalytic yield is only reduced by 0.5%, and after the catalyst is recycled for 5 times, the catalytic yield is still maintained to be more than 91%, which shows that the catalyst has good recycling performance.

In summary, it can be seen that: the catalyst used in the reaction is a product of acid-base reaction, namely a novel amine salt ionic liquid, and the ionic liquid has the advantages of easiness in preparation, low cost of raw materials, environmental friendliness, high catalyst activity and the like. Under the rather mild condition of 50 ℃, a small amount of ionic liquid catalyst is added, and the yield of the cyclic carbonate can reach more than 99 percent.