阅读说明：本技术 咪唑双离子液体及用其催化合成环状碳酸酯的方法 (Imidazole diionic liquid and method for catalytic synthesis of cyclic carbonate by using same ) 是由 王丽 张敬来 任铁钢 王腾飞 于 2019-10-28 设计创作，主要内容包括：本发明涉及咪唑双离子液体,其结构式如下所示：<Image he="81" wi="224" file="100004_DEST_PATH_IMAGE001.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>,式中n=1,2或3。本发明还给出了利用该咪唑双离子液体催化合成环状碳酸酯的方法,具体为：将咪唑双离子液体与环氧化合物按照摩尔比2~35∶100加入反应釜中,通入二氧化碳至压强为0.05~2 MPa,然后在温度为30~60℃条件下恒温恒压环加成反应1~12 h,反应结束后经后处理得到环状碳酸酯。该方法可在常温常压条件下进行,催化活性高,且不需要使用任何金属助催化剂和有机溶剂,解决了现有方法中存在的催化剂活性不高、反应条件苛刻、使用有机溶剂或助催化剂等问题。(The invention relates to imidazole diionic liquid, the structural formula of which is shown as follows: wherein n =1, 2 or 3. The invention also provides a method for synthesizing cyclic carbonate by using the imidazole diionic liquid as a catalyst, which comprises the following steps: adding imidazole diionic liquid and epoxy compound into a reaction kettle according to the mol ratio of 2-35: 100, introducing carbon dioxide until the pressure is 0.05-2 MPa, and then performing constant-temperature and constant-pressure cycloaddition reaction for 1-12 h at the temperature of 30-60 ℃ for reactionAfter the reaction, cyclic carbonate is obtained through post-treatment. The method can be carried out under the conditions of normal temperature and normal pressure, has high catalytic activity, does not need to use any metal cocatalyst and organic solvent, and solves the problems of low catalyst activity, harsh reaction conditions, use of organic solvent or cocatalyst and the like in the prior method.)

1. The imidazole diionic liquid is characterized in that the structural formula is as follows:

2. The preparation method of the imidazole diionic liquid as claimed in claim 1, which comprises the steps of:

reacting carboxyl imidazole hydrobromide with 1,1,3, 3-tetramethylguanidine at normal temperature for 6-18 h in the presence of a methanol solvent, and performing rotary evaporation, washing and drying after the reaction is finished to obtain the compound;

the molar ratio of the carboxyl imidazole hydrobromide to the 1,1,3, 3-tetramethyl guanidine is 1: 1-1.2;

the carboxyl imidazole hydrobromide is 1-carboxymethyl imidazole hydrobromide, 1-carboxyethyl imidazole hydrobromide or 1-carboxypropyl imidazole hydrobromide.

3. The method for catalytically synthesizing the cyclic carbonate by using the imidazole diionic liquid as claimed in claim 1, is characterized by comprising the following steps of:

adding imidazole diionic liquid and an epoxy compound into a reaction kettle according to the mol ratio of 2-35: 100, introducing carbon dioxide until the pressure is 0.05-2 MPa, carrying out constant-temperature and constant-pressure cycloaddition reaction for 1-12 h at the temperature of 30-60 ℃, and carrying out post-treatment after the reaction is finished to obtain the cyclic carbonate.

4. The method for catalytically synthesizing cyclic carbonate by using imidazole diionic liquid according to claim 3, wherein the epoxy compound is a compound of any one of the following structures:

5. the method for catalytically synthesizing cyclic carbonate by using the imidazole diionic liquid according to claim 3, wherein the molar ratio of the imidazole diionic liquid to the epoxy compound is 2-35: 100.

6. The method for catalytically synthesizing cyclic carbonate by using imidazole diionic liquid according to claim 3, wherein the temperature of the cycloaddition reaction is 30-60 ℃.

7. The method for catalytically synthesizing cyclic carbonate by using the imidazolium diionic liquid as claimed in claim 3, wherein the time of the cycloaddition reaction is 1-12 h.

Technical Field

The invention belongs to the technical field of environment-friendly catalysis, and particularly relates to an imidazole diionic liquid, a preparation method thereof, and a method for catalyzing carbon dioxide and an epoxy compound to react to generate cyclic carbonate by using the ionic liquid.

Background

CO₂As a main greenhouse gas, the green-house gas seriously affects the global environment and the social activities of human beings, but also is a cheap, rich, nontoxic and renewable C1 resource. CO 2₂Not only can reduce CO in the atmosphere₂The concentration of the (B) can provide sustainable supplement for limited fossil fuels, and chemical products with high added values can be obtained, which has great significance 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 effective and widely used method, and on one hand, the cycloaddition reaction has the characteristic of atom economy, by-products can be ignored, and on the other hand, the generated cyclic carbonate has wide application. The cyclic carbonate can be used as a polar aprotic solvent, an electrolyte for a fuel cell or a lithium ion battery due to its high boiling point, large dielectric constant, and large dipole moment. In addition, cyclic carbonates are also common intermediates for the synthesis of other compounds.

Since cyclic carbonates have important economic potential and broad application prospects, further improvement in catalyst performance is required to improve yield and reduce cost. Various homogeneous and heterogeneous catalysts have been reported for CO₂And epoxy compounds, including alkali metal salts, metal organic framework compounds, molecular sieves, and ionic liquids. The ionic liquid is distinguished from a plurality of catalysts by unique advantages, such as high thermal stability, low vapor pressure, incombustibility and the like. In recent decades, various ionic liquids have been developed, such as functionalized ionic liquids, dicationic ionic liquids, and bifunctional ionic liquids, but in the absence of metal promoters or organic solvents, general ionic liquids may still have one or more of the disadvantages of difficult synthesis, low catalytic activity, and harsh catalytic conditions. Therefore, it is necessary to search for a high-efficiency ionic liquid having a high catalytic activity under mild conditions.

Disclosure of Invention

In order to solve the technical problems of low catalyst activity, harsh reaction conditions, use of organic solvents and the like in the conventional method for synthesizing the cyclic carbonate, the invention aims to provide the method for synthesizing the cyclic carbonate by using the imidazole diionic liquid, which can be carried out under the conditions of normal temperature and normal pressure, has high catalytic activity and does not need any metal cocatalyst or organic solvent.

The invention also provides a preparation method of the imidazole diionic liquid.

In order to achieve the purpose, the invention adopts the following technical scheme:

an imidazole diionic liquid has a structural formula shown as follows:

wherein n =1, 2 or 3.

The invention provides a preparation method of the imidazole diionic liquid, which comprises the following steps:

reacting carboxyl imidazole hydrobromide with 1,1,3, 3-tetramethylguanidine at normal temperature for 6-18 h in the presence of a methanol solvent, and performing rotary evaporation, washing and drying after the reaction is finished to obtain the compound;

the molar ratio of the carboxyl imidazole hydrobromide to the 1,1,3, 3-tetramethyl guanidine is 1: 1-1.2;

the carboxyl imidazole hydrobromide is 1-carboxymethyl imidazole hydrobromide, 1-carboxyethyl imidazole hydrobromide or 1-carboxypropyl imidazole hydrobromide.

The invention also provides a method for synthesizing cyclic carbonate by using the imidazole diionic liquid as a catalyst, which comprises the following steps:

adding imidazole diionic liquid and an epoxy compound into a reaction kettle according to the mol ratio of 2-35: 100, introducing carbon dioxide until the pressure is 0.05-2 MPa, carrying out constant-temperature and constant-pressure cycloaddition reaction for 1-12 h at the temperature of 30-60 ℃, and carrying out post-treatment after the reaction is finished to obtain the cyclic carbonate.

Specifically, the epoxy compound is preferably one having any one of the following structuresCompound (I)

。

Further preferably, the molar ratio of the imidazole diionic liquid to the epoxy compound is 15-35: 100.

Further preferably, the temperature of the cycloaddition reaction is 30-50 ℃.

Further preferably, the time of the cycloaddition reaction is 3-12 h.

The invention provides an imidazole diionic liquid for catalyzing CO₂And a method for preparing cyclic carbonate by using an epoxy compound, namely using imidazole diionic liquid as a catalyst, and enabling CO to react under mild conditions without using a cocatalyst or a solvent₂And an epoxy compound to synthesize a cyclic carbonate through a cycloaddition reaction. CO 2₂The cyclic carbonate is prepared by cycloaddition reaction of epoxy compound and the compound, wherein R is CH₃、CH₂Cl、C₆H₅、CH₂OH、CH₂OCH₂CH=CH₂Or CH₂OC₆H₅And the like:

。

compared with the prior art, the invention has the following beneficial effects:

1) the imidazole diionic liquid provided by the invention can efficiently catalyze CO under the conditions of mildness (or normal temperature and pressure), no metal cocatalyst and no organic solvent₂And an epoxy compound to form a cyclic carbonate. The catalyst can catalyze epoxy compounds with different substituents and CO₂The cycloaddition reaction shows excellent universality;

2) after the cyclic carbonate is generated by catalysis, the cyclic carbonate can be easily separated under the condition of adding ethyl acetate, the recycling performance is good, and the cost is reduced. The catalyst catalyzesCO₂High activity in cycloaddition reaction with epoxy compounds, mild reaction conditions, no metal or solvent, high operation safety and good industrial application prospect.

Drawings

FIG. 1 is the [ TMGH ] prepared in example 1⁺][^-O₂PHIm⁺][Br^-]Nuclear magnetic resonance hydrogen spectrum of the catalyst.

FIG. 2 is the [ TMGH ] prepared in example 1⁺][^-O₂PHIm⁺][Br^-]Nuclear magnetic resonance carbon spectrum of the catalyst.

It can be seen from fig. 1 and 2 that the synthesized catalyst is the target catalyst.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments, and the following examples are only illustrative of the present invention and are not intended to limit the present invention.