Preparation method of asymmetric fluorocarbonate
By using N,N dicarbonylimidazole and organic base catalyst for esterification reaction under low temperature conditions, the problems of many side reactions and low purity in traditional methods are solved, and high-efficiency preparation of high-purity asymmetric fluorocarbonate is achieved, which is suitable for high-quality and suitable for the preparation of high-purity asymmetric fluorocarbonate. Industrial production.
Patent Information
- Application Number
- CN202310737264.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-21
- Publication Date
- 2024-12-24
AI Technical Summary
In the traditional synthesis methods of asymmetric fluorocarbonates, the raw material triphosgene and intermediate chloroformate have high toxicity, many side reactions, low reaction yield and low product purity, which leads to unfavorable industrial production.
Formation reaction with N,N dicarbonyl imidazole and polar aprotic organic solvent under low temperature conditions, followed by dropwise addition of non-fluorool, and esterification reaction in the presence of organic base catalyst, by washing and concentration of essence Distillation yields asymmetric fluorocarbonate of high purity.
It effectively avoids the generation of symmetric carbonate by-products, improves the esterification reaction efficiency, and obtains asymmetric fluorocarbonate with high yield and high purity. It has simple process, easy raw materials, low toxicity, and is suitable for industrialization.
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Figure CN119176750A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of lithium battery electrolyte solvent preparation, in particular to a method for preparing an asymmetric fluorinated carbonate. Background Art
[0002] In recent years, the demand for electric vehicles has been increasing day by day. The development of high-energy and high-power density lithium-ion batteries is the key to the large-scale commercialization of electric vehicles. The current commercial electrolytes are still unstable under high temperature and high pressure. One important reason is that conventional carbonate solvents have low flash points and poor thermal stability, which limits the high-temperature performance of the battery. When the voltage is higher than 4.5V, they will be continuously oxidized and decomposed on the cathode surface, seriously reducing the cycle stability of the battery.
[0003] The superior oxidation stability and flame retardancy of fluorinated carbonates make them very promising candidates for high-temperature and high-pressure electrolytes. The fluorinated substituents give them an electron-withdrawing effect, which can increase their oxidation potential and make the molecules more resistant to decomposition. Most fluorinated carbonates can form a double-layer passivation film on the electrode surface, reducing the degradation of the electrode surface and the decomposition of the electrolyte, thereby achieving long-term circulation.
[0004] At present, the traditional synthesis method of asymmetric fluorocarbonate is to prepare chloroformate intermediate by reacting triphosgene and alcohol, and then esterify chloroformate with fluoroalcohol under alkaline conditions to obtain asymmetric fluorocarbonate product. However, the technical problems existing in the traditional synthesis process are: the raw material triphosgene and the intermediate chloroformate are highly toxic, there are many side reactions, the reaction yield is low, and the product purity is low, which is very unfavorable for industrial production. Summary of the invention
[0005] The technical problem to be solved by the present invention is to provide a method for preparing an asymmetric fluorinated carbonate, which has easy-to-obtain raw materials, few side reactions, high purity and high yield.
[0006] In order to solve the above problems, the technical scheme adopted by the present invention is: a method for preparing an asymmetric fluorinated carbonate, comprising the following steps: 1. dissolving N, N-dicarbonyl imidazole in a polar non-protonic organic solvent, cooling, and dripping a non-fluorinated alcohol to carry out a formylation reaction, wherein the molar ratio of N, N-dicarbonyl imidazole to the non-fluorinated alcohol is 1.05-1.5, and after the dripping is completed, washing the reaction liquid with water; 2. cooling the reaction liquid after washing with water, and then dripping a mixed solution of a fluorinated alcohol and an organic base catalyst to carry out an esterification reaction, wherein the organic base catalyst is selected from triethylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene (abbreviated as DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (abbreviated as DBN), and 1,4-diazabicyclo[2.2.2]octane (abbreviated as DABCO); 3. washing the reaction liquid with water, concentrating, and distilling to obtain an asymmetric fluorinated carbonate product.
[0007] The above reaction principle is shown as follows: ; Where R 1 OH represents non-fluorinated alcohol, R 2 OH represents a fluoroalcohol.
[0008] Furthermore, in the aforementioned method for preparing an asymmetric fluorocarbonate, the polar aprotic organic solvent is selected from one of dichloromethane, dichloroethane, chloroform, ethyl ether, methyl tert-butyl ether, tetrahydrofuran, dioxane, acetone, and acetonitrile.
[0009] Furthermore, in the aforementioned method for preparing an asymmetric fluorocarbonate, the polar aprotic organic solvent is dichloromethane.
[0010] Furthermore, in the aforementioned method for preparing an asymmetric fluorinated carbonate, the non-fluorinated alcohol is selected from one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, allyl alcohol, propargyl alcohol, phenol, and benzyl alcohol; and the molar ratio of N,N-dicarbonylimidazole to the non-fluorinated alcohol is 1.1 to 1.2.
[0011] Furthermore, in the aforementioned method for preparing an asymmetric fluorocarbonate, the fluoroalcohol is selected from one of trifluoroethanol, difluoroethanol, fluoromethanol, hexafluoroisopropanol and tetrafluoropropanol.
[0012] Furthermore, in the aforementioned method for preparing an asymmetric fluorinated carbonate, the molar ratio of the organic base catalyst to the fluorinated alcohol is 0.01 to 0.1.
[0013] Furthermore, in the aforementioned method for preparing an asymmetric fluorinated carbonate, the molar ratio of the organic base catalyst to the fluorinated alcohol is 0.05.
[0014] Furthermore, in the aforementioned method for preparing an asymmetric fluorocarbonate, the organic base catalyst is 1,5-diazabicyclo[4.3.0]non-5-ene.
[0015] Furthermore, in the aforementioned method for preparing an asymmetric fluorinated carbonate, in the second step, after the mixed solution of the fluorinated alcohol and the organic base catalyst is added dropwise, the esterification reaction is carried out for 0.5 to 3 hours.
[0016] Furthermore, in the aforementioned method for preparing an asymmetric fluorinated carbonate, in the first step, the non-fluorinated alcohol is added dropwise after the temperature is lowered to -15°C to 0°C; in the second step, the reaction solution is cooled to -15°C to 0°C after washing with water.
[0017] The advantages of the present invention are: in the first step, polar aprotic organic solvent is used to dilute N, N-dicarbonyl imidazole, low temperature conditions, slightly excessive N, N-dicarbonyl imidazole, and non-fluorinated alcohol is added in a dropwise manner, which effectively avoids the generation of symmetrical carbonate byproducts in the first step reaction; in the second step, an organic base catalyst is used to activate the fluoroalcohol, which enhances its nucleophilicity, thereby promoting the esterification reaction to proceed efficiently, thereby obtaining a high-purity product asymmetrical fluorocarbonate at a high yield. The entire process is simple, the raw materials are easily available, the toxicity is low, the post-processing is convenient, and the product purity and yield are high. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 This is the H NMR spectrum of the product prepared in Example 3. 1 H NMR (400MHz, CDCl3)δ4.49 (2H,q, J = 4.0 Hz), 4.26 (2H, q, J = 4 Hz), 1.33 (3H, t, J = 8.0Hz).
[0019] Figure 2 This is the NMR carbon spectrum of the product prepared in Example 3. 13 C NMR (100MHz, CDCl3) δ154.13, 125.56, 123.72, 121.88, 120.05, 65.53, 63.82, 63.58, 63.33, 63.08, 14.27.
[0020] Figure 3 This is the NMR fluorine spectrum of the product prepared in Example 3. 19 F NMR (376MHz, CDCl3)δ-74.35-74.43 (m). Implementation
[0021] The present invention is further described in detail below in conjunction with preferred embodiments.
[0022] Example 1: In a three-necked jacketed reactor equipped with a thermometer, a stirrer, and a constant pressure dropping funnel, 211 g of N, N-dicarbonyl imidazole and 1.2 kg of dichloroethane were added, and after cooling to -15 ° C, 60 g of n-propanol was added dropwise. After the addition was complete, the reaction solution was washed with water once, and then cooled to -15 ° C. A mixed solution of 100 g of trifluoroethanol and 10 g of triethylamine was added dropwise. After the addition was complete, the reaction was kept warm for 0.5 h and the reaction was stopped.
[0023] The reaction solution was washed with water three times and then concentrated to remove dichloroethane. The concentrate was distilled under reduced pressure to obtain 174 g of trifluoroethylpropyl carbonate. The purity was 99.92% as determined by GC (gas chromatography). The molar yield was calculated to be 93.55%.
[0024] Example 2: In a three-necked jacketed reactor equipped with a thermometer, a stirrer, and a constant pressure dropping funnel, 195 g of N,N-dicarbonyl imidazole and 1.5 kg of dichloromethane were added, and after cooling to -10 ° C, 32 g of methanol was added dropwise. After the addition was complete, the reaction solution was washed with water once, and then cooled to -10 ° C. A mixed solution of 100 g of trifluoroethanol and 6.2 g of DBN was added dropwise. After the addition was complete, the reaction was kept warm for 1 h and the reaction was stopped.
[0025] The reaction solution was washed with water three times and then concentrated to remove dichloromethane. The concentrate was distilled under reduced pressure to obtain 154 g of trifluoroethyl methyl carbonate. The purity was 99.98% as determined by GC (gas chromatography). The molar yield was calculated to be 97.47%.
[0026] Example 3: In a three-necked jacketed reactor equipped with a thermometer, a stirrer, and a constant pressure dropping funnel, 179 g of N,N-dicarbonyl imidazole and 1.5 kg of chloroform were added, and after cooling to -6 ° C, 46 g of ethanol was added dropwise. After the addition was complete, the reaction solution was washed with water once, and then cooled to -6 ° C. A mixed solution of 100 g of trifluoroethanol and 7.6 g of DBU was added dropwise. After the addition was complete, the reaction was kept warm for 0.5 h and the reaction was stopped.
[0027] The reaction solution was washed with water three times and concentrated to remove chloroform. The concentrate was distilled under reduced pressure to obtain 163 g of trifluoroethyl ethyl carbonate. The purity was 99.94% as determined by GC (gas chromatography). The molar yield was calculated to be 94.77%. Figure 1 is the H NMR spectrum of the product, 1 H NMR (400MHz, CDCl3)δ4.49 (2H, q, J = 4.0 Hz), 4.26 (2H, q, J = 4Hz), 1.33 (3H, t, J = 8.0Hz); Figure 2 The NMR carbon spectrum of the product is 13 C NMR(100MHz, CDCl3)δ154.13, 125.56, 123.72, 121.88, 120.05, 65.53, 63.82, 63.58, 63.33, 63.08,14.27; Figure 3 The NMR fluorine spectrum of the product 19 F NMR (376MHz, CDCl3)δ-74.35-74.43 (m).
[0028] Example 4: In a three-necked jacketed reactor equipped with a thermometer, a stirrer, and a constant pressure adding funnel, 227 g of N,N-dicarbonyl imidazole and 1.2 kg of methyl tert-butyl ether were added, and after cooling to -5 ° C, 60 g of isopropanol was added dropwise. After the addition was complete, the reaction solution was washed with water once, and then cooled to -5 ° C. A mixed solution of 50 g of fluoromethanol and 10 g of DABCO was added dropwise. After the addition was complete, the reaction was kept warm for 2 h to stop the reaction.
[0029] The reaction solution was washed with water three times and then concentrated to remove methyl tert-butyl ether. The concentrate was distilled under reduced pressure to obtain 126 g of fluoromethyl isopropyl carbonate. The purity was 99.93% as determined by GC (gas chromatography). The calculated molar yield was 92.65%.
[0030] Example 5: In a three-necked jacketed reactor equipped with a thermometer, a stirrer, and a constant pressure dropping funnel, 195 g of N,N-dicarbonyl imidazole and 1.5 kg of dichloromethane were added, and after cooling to -10 ° C, 56 g of propargyl alcohol was added dropwise. After the addition was complete, the reaction solution was washed with water once, and then cooled to -10 ° C, and a mixed solution of 100 g of trifluoroethanol and 6.2 g of DBN was added dropwise. After the addition was complete, the reaction was kept warm for 1 h and the reaction was stopped.
[0031] The reaction solution was washed with water three times and then concentrated to remove dichloromethane. The concentrate was distilled under reduced pressure to obtain 178 g of trifluoroethyl propargyl carbonate. The purity was 99.97% as determined by GC (gas chromatography). The molar yield was calculated to be 97.80%.
[0032] Example 6: Into a three-necked jacketed kettle equipped with a thermometer, a stirrer and a constant pressure adding funnel, 211 g of N,N-dicarbonylimidazole and 1.2 kg of tetrahydrofuran were added, and after cooling to -5°C, 74 g of n-butanol was added dropwise. After the addition was complete, the reaction solution was washed with water, and then cooled to -5°C. A mixed solution of 82 g of difluoroethanol and 10 g of triethylamine was added dropwise. After the addition was complete, the reaction was kept warm for 5 h and the reaction was stopped.
[0033] The reaction solution was washed with water three times and concentrated to remove tetrahydrofuran. The concentrate was distilled under reduced pressure to obtain 171 g of difluoroethyl n-butyl carbonate. The purity was 99.96% as determined by GC (gas chromatography). The calculated molar yield was 93.96%.
[0034] Example 7: In a three-necked jacketed reactor equipped with a thermometer, a stirrer, and a constant pressure adding funnel, 243 g of N,N-dicarbonyl imidazole and 1.2 kg of acetone were added, and after cooling to 0°C, 74 g of tert-butanol was added dropwise. After the addition was complete, the reaction solution was washed with water once, and then cooled to 0°C. A mixed solution of 168 g of hexafluoroisopropanol and 15 g of DBU was added dropwise. After the addition was complete, the reaction was kept warm for 3 h and the reaction was stopped.
[0035] The reaction solution was washed with water three times and then concentrated to remove acetone. The concentrate was distilled under reduced pressure to obtain 249 g of hexafluoroisopropyl tert-butyl carbonate. The purity was 99.91% as determined by GC (gas chromatography). The molar yield was calculated to be 92.91%.
[0036] Comparative Example 8: 1. Add 300g of triphosgene and 2.5Kg of dichloromethane to a three-necked jacketed kettle equipped with a thermometer, a stirrer and a constant pressure dropping funnel. After cooling to -5°C, add a mixed solution of 138g of ethanol and 280g of pyridine. After the addition is completed, react at room temperature for 1h, stop the reaction, filter, wash the filtrate with water, concentrate to remove dichloromethane, and distill the concentrate under reduced pressure to obtain 195g of ethyl chloroformate. The purity was 98.26% as detected by GC (gas chromatography), and the molar yield was calculated to be 59.63%.
[0037] 2. Add 100g of trifluoroethanol, 109g of ethyl chloroformate and 360g of ether to a three-necked jacketed kettle equipped with a thermometer, a stirrer and a constant pressure dropping funnel. After cooling to -5°C, add 188g of a 30% potassium hydroxide aqueous solution dropwise. After the addition is complete, react at room temperature for 12h and then stop the reaction.
[0038] The reaction solution was washed with water three times and then concentrated to remove ether. The concentrate was distilled under reduced pressure to obtain 95 g of trifluoroethyl ethyl carbonate. The purity was 94.31% as determined by GC (gas chromatography). The calculated molar yield was 55.23%.
[0039] The experimental results of Example 8 illustrate that the method of synthesizing asymmetric fluorocarbonates using triphosgene has technical problems such as low yield, many by-products, and low product purity.
[0040] From the above examples 1 to 7, it can be seen that the preparation method of the asymmetric fluorinated carbonate of the present invention, in the first step, a polar aprotic organic solvent is used to dilute N, N dicarbonyl imidazole, low temperature conditions, slightly excessive N, N dicarbonyl imidazole, and non-fluorinated alcohol is added dropwise, which effectively avoids the formation of symmetric carbonate byproducts in the first step reaction; in the second step, an organic base catalyst is used to activate the fluorinated alcohol, which enhances its nucleophilicity, thereby promoting the esterification reaction to proceed efficiently, thereby obtaining a high-purity product asymmetric fluorinated carbonate at a high yield. The entire process is simple, the raw materials are easily available, the toxicity is low, the post-processing is convenient, the product purity and yield are very high, and it is extremely conducive to industrialization.
Claims
1. A method for preparing an asymmetric fluorocarbonate, comprising the following steps:
1. Dissolve N,N-dicarbonyl imidazole in a polar non-protonic organic solvent, cool down, and drop non-fluorinated alcohol to carry out formylation reaction, wherein the molar ratio of N,N-dicarbonyl imidazole to non-fluorinated alcohol is 1.05-1.5, and wash the reaction solution with water after the dropwise addition is completed; 2. Cool down the reaction solution after water washing, and then drop a mixed solution of fluorinated alcohol and organic base catalyst to carry out esterification reaction, wherein the organic base catalyst is selected from triethylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5-diazabicyclo[4.3.0]non-5-ene, 1,4-diazabicyclo[2.2.2]octane; 3. Wash the reaction solution with water, concentrate and rectify to obtain an asymmetric fluorinated carbonate product.
2. The method for preparing an asymmetric fluorinated carbonate according to claim 1, characterized in that: The polar aprotic organic solvent is selected from one of dichloromethane, dichloroethane, chloroform, ethyl ether, methyl tert-butyl ether, tetrahydrofuran, dioxane, acetone and acetonitrile.
3. The method for preparing an asymmetric fluorinated carbonate according to claim 2, characterized in that: The polar aprotic organic solvent used was dichloromethane.
4. The method for preparing an asymmetric fluorinated carbonate according to claim 1, characterized in that: The non-fluorinated alcohol is selected from one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, allyl alcohol, propargyl alcohol, phenol and benzyl alcohol; the molar ratio of N,N-dicarbonyl imidazole to the non-fluorinated alcohol is 1.1-1.
2.
5. The method for preparing an asymmetric fluorinated carbonate according to claim 1, characterized in that: The fluoroalcohol is selected from one of trifluoroethanol, difluoroethanol, fluoromethanol, hexafluoroisopropanol and tetrafluoropropanol.
6. The method for preparing an asymmetric fluorinated carbonate according to claim 1, characterized in that: The molar ratio of the organic base catalyst to the fluoroalcohol is 0.01 to 0.
1.
7. The method for preparing an asymmetric fluorinated carbonate according to claim 6, characterized in that: The molar ratio of the organic base catalyst to the fluoroalcohol is 0.
05.
8. A method for preparing an asymmetric fluorinated carbonate according to claim 1, 6 or 7, characterized in that: The organic base catalyst is 1,5-diazabicyclo[4.3.0]non-5-ene.
9. The method for preparing an asymmetric fluorinated carbonate according to claim 1, characterized in that: In the second step, after the mixed solution of the fluoroalcohol and the organic base catalyst is added dropwise, the esterification reaction is carried out for 0.5 to 3 hours.
10. The method for preparing an asymmetric fluorinated carbonate according to claim 1, characterized in that: In the first step, the non-fluorinated alcohol is added dropwise after the temperature is lowered to -15°C to 0°C; in the second step, the reaction solution is cooled to -15°C to 0°C after washing with water.