Preparation method of 2-cyanoethyl trimethoxy silane
By using cyclic treatment of ethanol and anhydrous methanol in the reaction vessel, combined with the negative pressure removal and low boiling technology, the purity of 2-cyanoethyl trimethoxysilane was successfully improved, the problem of insufficient purity in the prior art was solved, and the industrial application of high-purity products was achieved.
Patent Information
- Application Number
- CN202311822951.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-27
- Publication Date
- 2025-06-27
AI Technical Summary
In the prior art, the purity of 2-cyanoethyltrimethoxysilane is insufficient and cannot meet the requirements as an electrolyte additive.
2-cyanoethyl trichlorosilane is added dropwise under the condition of adding ethanol to the reaction vessel, heating to reflux and maintaining inert gas bubbles, and the reaction temperature is controlled to be no less than 70°C. Then, the purity of the product is gradually improved by adding anhydrous methanol and removing the low boiling operation after several times and removing the low boiling operation of negative pressure.
It has achieved high purity preparation of 2-cyanoethyl trimethoxysilane, with a product purity of more than 99.3%, which is suitable for lithium battery electrolyte and is suitable for industrial promotion.
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of organic synthesis, and particularly to the synthesis of 2-cyanoethyltrimethoxysilane. Background Art
[0002] At present, the preparation methods of 2-cyanoethyltrimethoxysilane reported at home and abroad mainly include the following two methods: First, 2-cyanoethyltrichlorosilane reacts with methanol under the condition of an acid-binding agent to generate the target product; Second, 2-cyanoethyltrichlorosilane is added with methanol under the condition of solvent entrainment to remove hydrogen chloride to obtain the target product.
[0003] At present, the purity of 2-cyanoethyltrimethoxysilane prepared by the above two methods in the market is basically 97% - 98%, and the main impurity is the hydrolyzate of 2-cyanoethyltrimethoxysilane, which is difficult to remove by conventional methods. Obviously, the purity of the products prepared by the above two methods cannot meet the requirements for use as an electrolyte additive. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide a preparation method of 2-cyanoethyltrimethoxysilane, which has simple operation, mild and controllable reaction, high product purity and is suitable for industrial promotion.
[0005] To achieve the above object, the technical solution adopted by the present invention is: A preparation method of 2-cyanoethyltrimethoxysilane, comprising the following steps: First, add ethanol to a reaction vessel, heat up to reflux and maintain reflux, and dropwise add 2-cyanoethyltrichlorosilane under the condition of inert gas bubbling, control the dropping rate so that the reaction temperature is not lower than 70 °C, after the dropping is completed, keep the reaction under heat preservation, remove the excessive ethanol under vacuum conditions, and the pH of the intermediate crude product is 6 - 7; The second step: Control the temperature of the crude product obtained in the first step at 0 - 10 °C, add solid base with a mass of 10% - 20% of the crude product; then, add anhydrous methanol, heat up to reflux and keep the reaction under heat preservation, then remove the low-boiling components under negative pressure; add anhydrous methanol again, heat up to reflux and keep the reaction under heat preservation, and then remove the low-boiling components under negative pressure again; the above steps are repeated 3 - 7 times in total, and the crude product after removing the low-boiling components is rectified under negative pressure to obtain the finished product.
[0006] Further, in the above-mentioned preparation method of 2-cyanoethyltrimethoxysilane, in the first step, the mass ratio of 2-cyanoethyltrichlorosilane to ethanol is 1:3 - 5.
[0007] Further, in the above-mentioned preparation method of 2-cyanoethyltrimethoxysilane, in the first step, inert gas bubbling is always maintained during the reaction process, and the dropping rate is controlled so that the reaction temperature is controlled at 70 - 75 °C.
[0008] Further, in the aforementioned method for preparing 2-cyanoethyltrimethoxysilane, in the first step, after the dropwise addition of 2-cyanoethyltrichlorosilane is completed, the reaction is carried out under heat preservation for 1 to 3 hours.
[0009] Further, in the aforementioned method for preparing 2-cyanoethyltrimethoxysilane, in the second step, the solid base is one or more of potassium carbonate, sodium carbonate, and sodium methoxide.
[0010] Further, in the aforementioned method for preparing 2-cyanoethyltrimethoxysilane, in the second step, the mass of the anhydrous methanol added at one time is 3 to 5 times the mass of the crude product.
[0011] Further, in the aforementioned method for preparing 2-cyanoethyltrimethoxysilane, in the second step, after each addition of anhydrous methanol, the temperature is raised to reflux and the reaction is carried out under heat preservation for 1 hour.
[0012] Further, in the aforementioned method for preparing 2-cyanoethyltrimethoxysilane, in the second step, the operation of adding anhydrous methanol for reflux reaction and then removing low-boiling substances under negative pressure is repeated 5 times.
[0013] The advantages of the present invention are as follows: The preparation method of 2-cyanoethyltrimethoxysilane described in the present invention has few technological steps in the synthesis method, is simple and easy to operate, has a high purity of the finished product, can be directly used in lithium battery electrolytes, and is suitable for industrial promotion. Specific Embodiments
[0014] The present invention will be further described in detail below in conjunction with preferred embodiments.
[0015] Example 1: Add 565.5 g of anhydrous ethanol to a three-necked flask equipped with a mechanical stirrer, a thermometer, and a tail gas absorption device, heat up to 78 °C for reflux, and dropwise add 188.5 g of 2-cyanoethyltrichlorosilane under the condition of nitrogen bubbling. Control the dropping rate to keep the reaction temperature at 70 to 75 °C. After the dropwise addition is completed, carry out reflux under heat preservation for 1 hour, and remove ethanol under negative pressure to obtain 220 g of crude 2-cyanoethyltriethoxysilane, with a pH value of 6 to 7.
[0016] Cool down to 0 °C and add 22 g of solid sodium methoxide. Then, add 660 g of methanol and heat up to 70 °C for reflux for 1 hour, and then remove low-boiling substances under negative pressure; add 660 g of anhydrous methanol again, continue to heat up to 70 °C for reflux for 1 hour, and then remove low-boiling substances under negative pressure; the above operation is repeated 5 times. Finally, after evaporating the solvent, 195 g of crude 2-cyanoethyltrimethoxysilane is obtained, and 157 g of the finished product is obtained by rectification under negative pressure, with a GC purity of 99.3% and a total yield of 89.7%.
[0017] Example 2: Add 377 g of absolute ethanol into a three-necked flask equipped with mechanical stirring, a thermometer, and a tail gas absorption device. Heat it to reflux at 78 °C. Under the condition of bubbling nitrogen, dropwise add 94.25 g of 2-cyanoethyltrichlorosilane, control the dropping rate to keep the reaction temperature at 70 - 75 °C. After the dropping is completed, keep the temperature for reflux for 3 h. Then, remove ethanol under negative pressure to obtain 105 g of crude 2-cyanoethyltriethoxysilane, with a pH value of 6 - 7.
[0018] Cool down to 5 °C and add 21 g of solid potassium carbonate. Then, add 315 g of methanol and heat it to reflux at 70 °C for 1 h. Next, remove low-boiling substances under negative pressure; add 315 g of absolute methanol again, continue to heat it to reflux at 70 °C for 1 h, and then remove low-boiling substances under negative pressure again; the above operations are repeated 3 times in total. Finally, after evaporating the solvent, 97 g of crude 2-cyanoethyltrimethoxysilane is obtained. After rectification under negative pressure, 72.5 g of the finished product is obtained, with a GC purity of 99.1% and a final yield of 82.9%.
[0019] Example 3: Add 1885 g of absolute ethanol into a three-necked flask equipped with mechanical stirring, a thermometer, and a tail gas absorption device. Heat it to reflux at 78 °C. Under the condition of bubbling nitrogen, dropwise add 377 g of 2-cyanoethyltrichlorosilane, control the dropping rate to keep the reaction temperature at 70 - 75 °C. After the dropping is completed, keep the temperature for reflux for 2 h. Then, remove ethanol under negative pressure to obtain 420 g of crude 2-cyanoethyltriethoxysilane, with a pH value of 6 - 7.
[0020] Cool down to 0 °C and add 63 g of solid sodium carbonate. Then, add 1680 g of methanol and heat it to reflux at 70 °C for 1 h. Next, remove low-boiling substances under negative pressure; add 1680 g of absolute methanol again, continue to heat it to reflux at 70 °C for 1 h, and then remove low-boiling substances under negative pressure again; the above operations are repeated 7 times in total. Finally, after evaporating the solvent, 390 g of crude 2-cyanoethyltrimethoxysilane is obtained. After rectification under negative pressure, 316 g of the finished product is obtained, with a GC purity of 99.6% and a final yield of 90.3%.
[0021] Example 4: Add 565.5 g of absolute ethanol into a three-necked flask equipped with mechanical stirring, a thermometer, and a tail gas absorption device. Heat it to reflux at 78 °C. Under the condition of bubbling nitrogen, dropwise add 188.5 g of 2-cyanoethyltrichlorosilane, control the dropping rate to keep the reaction temperature at 70 - 75 °C. After the dropping is completed, keep the temperature for reflux for 3 h. Remove ethanol under negative pressure to obtain 212 g of crude 2-cyanoethyltriethoxysilane, with a pH value of 6 - 7.
[0022] Cool down to 5°C and add 22 g of potassium carbonate solid. Then, add 848 g of methanol and heat up to 70°C for reflux for 1 h. Next, remove the low-boiling substances under negative pressure; add 848 g of anhydrous methanol again, continue to heat up to 70°C for reflux for 1 h, and then remove the low-boiling substances under negative pressure again; the above operations are repeated 5 times in total. Finally, after evaporating the solvent, 180 g of crude 2-cyanoethyltrimethoxysilane is obtained. After rectification under negative pressure, 138 g of the finished product is obtained, with a GC purity of 99.5% and a total yield of 78.9%.
[0023] Example 5: Add 471.25 g of anhydrous ethanol to a three-necked flask equipped with a mechanical stirrer, a thermometer, and a tail gas absorption device, heat up to 78°C for reflux, and dropwise add 94.25 g of 2-cyanoethyltrichlorosilane under a nitrogen atmosphere. Control the dropping rate to keep the reaction temperature at 70 - 75°C. After the addition is completed, keep the temperature for reflux for 2 h. Then, remove ethanol under negative pressure to obtain 96 g of crude 2-cyanoethyltriethoxysilane, with a pH value of 6 - 7.
[0024] Cool down to about 5°C and add 19.2 g of sodium carbonate solid. Then, add 288 g of methanol and heat up to 70°C for reflux for 1 h. Next, remove the low-boiling substances under negative pressure; add 288 g of anhydrous methanol again, continue to heat up to 70°C for reflux for 1 h, and then remove the low-boiling substances under negative pressure again; the above operations are repeated 3 times in total. Finally, after evaporating the solvent, 86 g of crude 2-cyanoethyltrimethoxysilane is obtained. After rectification under negative pressure, 62 g of the finished product is obtained, with a GC purity of 99.1% and a final yield of 70.9%.
[0025] From the above examples, it can be obtained that the preparation method of 2-cyanoethyltrimethoxysilane according to the present invention has fewer technological steps in the synthesis method, is simple and easy to operate, has a high purity of the finished product, can be directly used in lithium battery electrolytes, and is suitable for industrial promotion.
Claims
1. A preparation method of 2-cyanoethyltrimethoxysilane, comprising the following steps:
1. Add ethanol to the reaction vessel, heat it to reflux and maintain reflux. While bubbling with an inert gas, dropwise add 2-cyanoethyltrichlorosilane, control the dropping rate so that the reaction temperature is not lower than 70 °C. After the addition is complete, keep the reaction under heat preservation, and remove the excess ethanol under vacuum. The pH of the crude intermediate product is between 6 and 7. Second step: Control the temperature of the crude product obtained in the first step at 0 - 10 °C, and add a solid base with a mass of 10% - 20% of the crude product. Then, add anhydrous methanol, heat it to reflux and keep the reaction under heat preservation, and then remove the low-boiling components under negative pressure. Add anhydrous methanol again, heat it to reflux and keep the reaction under heat preservation, and then remove the low-boiling components under negative pressure again. The above steps are repeated 3 - 7 times. The crude product after removing the low-boiling components is rectified under negative pressure to obtain the finished product.
2. The preparation method of 2-cyanoethyltrimethoxysilane according to claim 1, characterized in that: In the first step, the mass ratio of 2-cyanoethyltrichlorosilane to ethanol is 1:3 - 5.
3. The preparation method of 2-cyanoethyltrimethoxysilane according to claim 1, characterized in that: In the first step, keep bubbling with an inert gas throughout the reaction process, and control the dropping rate so that the reaction temperature is controlled at 70 - 75 °C.
4. The preparation method of 2-cyanoethyltrimethoxysilane according to claim 1, characterized in that: In the first step, after the addition of 2-cyanoethyltrichlorosilane is complete, keep the reaction under heat preservation for 1 - 3 h.
5. The preparation method of 2-cyanoethyltrimethoxysilane according to claim 1, characterized in that: In the second step, the solid base is one or more of potassium carbonate, sodium carbonate, and sodium methoxide.
6. The preparation method of 2-cyanoethyltrimethoxysilane according to claim 1, characterized in that: In the second step, the mass of anhydrous methanol added at one time is 3 - 5 times the mass of the crude product.
7. The preparation method of 2-cyanoethyltrimethoxysilane according to claim 1, characterized in that: In the second step, after adding anhydrous methanol each time, heat it to reflux and keep the reaction under heat preservation for 1 h.
8. The preparation method of 2-cyanoethyltrimethoxysilane according to claim 1, characterized in that: In the second step, the operation of adding anhydrous methanol for reflux reaction and then removing the low-boiling components under negative pressure is repeated 5 times.