Preparation method of methyl trifluoroethyl carbonate

Abstract

The invention relates to a preparation method of methyl trifluoroethyl carbonate. The preparation method comprises the following steps: (1) carrying out a reaction on di-tert-butyl dicarbonate and trifluoroethanol to obtain an intermediate product; (2) adding dimethyl carbonate into the reaction system in the step (1), and reacting to obtain methyl trifluoroethyl carbonate; the reaction in the step (1) is carried out in the presence of a catalyst. The preparation method has the advantages of few reaction steps and high selectivity and yield. Compared with the existing synthesis method, the synthesis raw material is di-tert-butyl dicarbonate, high-toxicity raw materials such as methyl chloroformate are avoided, and the method is green and environment-friendly. And methanol which can generate ternary azeotropy with the product FEC and the dimethyl carbonate during rectification is not generated in a reaction system, so that the product purity is improved. In addition, the reaction product carbon dioxide in the step (2) escapes, the reaction is promoted to proceed forwards, and the reaction yield is increased.

Description

Technical Field

[0001] The invention relates to the technical field of carbonates, in particular to a method for preparing methyl trifluoroethyl carbonate. Background Art

[0002] In recent years, the demand for fluorinated additives as functional electrolyte additives has continued to increase. The fluorine atoms in the fluorinated additives replace hydrogen, which can effectively increase the oxidation potential and reduction potential of the electrolyte, thereby improving the battery cycle performance. Ethyl trifluoroethyl carbonate (ETFEC), bis (trifluoroethyl carbonate) (TFEC), ethyl trifluoroacetate (ETFA), methyl trifluoroethyl carbonate (FEMC), etc. are representative products of fluorinated additives. With the growth of demand for the application of fluorinated additives, the development speed of the FEMC industry will further accelerate.

[0003] Methyl trifluoroethyl carbonate (FEMC), also known as fluoroethane methyl carbonate and (2,2,2-trifluoroethyl) methyl carbonate, has the molecular formula C4H5F3O3 and is a colorless liquid with the advantages of good chemical stability, flame retardancy, high voltage resistance, good film-forming properties, and low viscosity. As a fluorinated electrolyte additive, it has broad application prospects in the field of lithium-ion batteries. FEMC is widely used to solve the problems of silicon negative electrode capacity attenuation and volume expansion. This is because the solid electrolyte interface (SEI) derived from FEMC is rich in lithium fluoride and organic matter, has good mechanical properties, and can effectively avoid SEI rupture caused by the volume change of silicon negative electrode during the cycle.

[0004] There are three main methods for synthesizing and preparing FEMCs:

[0005] Method 1: FEMC is prepared by direct reaction of trifluoroethanol and methyl chloroformate under the action of an acid-binding agent, such as the preparation method using alkali as an acid-binding agent proposed in CN115784888A, CN 117586121A, and WO2021055560. The disadvantage of this method is that a large amount of alkali solution is used as an acid-binding agent in the synthesis of the target product, forming a large amount of high-salt waste, increasing costs, high raw material costs, high toxicity, high requirements for equipment and personnel, huge investment costs, and is not conducive to rapid and safe production.

[0006] Method 2: Using trifluoroethanol and carbonate as raw materials to react and prepare FEMC, such as the one-step method proposed in CN 115594585A to directly synthesize FEMC under the action of a catalyst, and the two-step method proposed in CN 114456068A to synthesize FEMC under the action of a catalyst and methanol. The disadvantage of this method is that dimethyl carbonate and the product FEMC have similar boiling points, and they form a ternary azeotropic reaction with methanol during distillation, so the product is difficult to separate and has a low purity.

[0007] Method 3: Using trifluoroethanol, N,N'-carbonyldiimidazole and methanol as raw materials to react in the presence of a catalyst to prepare FEMC, such as the synthesis of FEMC under low temperature conditions with a catalyst as proposed in patent CN111018709A. The disadvantage of this method is that it has high requirements for reaction temperature and equipment, is relatively complicated to operate, requires a large amount of raw materials and equipment, produces a lot of three wastes, and is not in line with green chemical production.

[0008] The preparation method of methyl trifluoroethyl carbonate in the prior art has the disadvantages of high raw material cost, high toxicity, low product yield and purity, and being unfavorable for large-scale production. Therefore, how to solve the above-mentioned shortcomings has become a problem to be solved urgently. Summary of the invention

[0009] The present invention aims to overcome the shortcomings of the prior art and provide a method for preparing methyl trifluoroethyl carbonate which is different from the prior art. In order to solve the above technical problems, the present invention uses di-tert-butyl dicarbonate, trifluoroethanol and dimethyl carbonate as reaction raw materials, the reaction operation is simple, the product has high purity and high yield, and is suitable for large-scale production.

[0010] To achieve this object, the present invention adopts the following technical solutions:

[0011] The present invention provides a method for preparing methyl trifluoroethyl carbonate, which comprises the following steps:

[0012] (1) reacting di-tert-butyl dicarbonate and trifluoroethanol to obtain an intermediate product;

[0013] (2) adding dimethyl carbonate to the reaction system of step (1), reacting to obtain methyl trifluoroethyl carbonate;

[0014] The reaction in step (1) is carried out in the presence of a catalyst.

[0015] The preparation method of the present invention has few reaction steps, high selectivity and high yield. Compared with the existing synthesis method, the synthesis raw material of the present invention is di-tert-butyl dicarbonate, which avoids the use of highly toxic raw materials such as methyl chloroformate, and is green and environmentally friendly. Methanol that will produce ternary azeotropy with the product FEMC and dimethyl carbonate during distillation is not generated in the reaction system, thereby improving the purity of the crude product. In addition, the reaction product carbon dioxide in step (2) of the present invention will escape, promote the forward reaction, and improve the reaction yield.

[0016] Preferably, the molar ratio of trifluoroethanol to di-tert-butyl dicarbonate is (2.0-2.8):1, for example, it can be 2.1:1, 2.12:1, 2.14:1, 2.16:1, 2.18:1, 2.2:1, 2.22:1, 2.24:1, 2.26:1, 2.28:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, etc., and is more preferably (2.1-2.3):1.

[0017] If the molar ratio of trifluoroethanol to di-tert-butyl dicarbonate is too large, the trifluoroethanol content in the crude product increases and the product yield after distillation decreases; if the molar ratio of trifluoroethanol to di-tert-butyl dicarbonate is too small, the reaction cannot be fully carried out and the yield decreases.

[0018] In the present invention, the crude product refers to the product after the reaction in step (2) is completed but before distillation.

[0019] Preferably, the catalyst includes any one of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, sodium methoxide, sodium ethoxide, or a combination of at least two thereof, and more preferably sodium methoxide and / or sodium hydroxide.

[0020] Preferably, the mass ratio of the catalyst to di-tert-butyl dicarbonate is (0.1-0.25):1, for example, it can be 0.12:1, 0.14:1, 0.155:1, 0.16:1, 0.165:1, 0.17:1, 0.175:1, 0.18:1, 0.20:1, 0.22:1, 0.24:1, etc., and is more preferably (0.15-0.18):1.

[0021] If the mass ratio of the catalyst to di-tert-butyl dicarbonate is too large, not only will the yield not be improved, but the catalyst will also be wasted; if the mass ratio of the catalyst to di-tert-butyl dicarbonate is too small, the reaction will not proceed sufficiently and the yield will be reduced.

[0022] Preferably, the reaction temperature in step (1) is 110°C to 130°C, for example, it can be 113°C, 116°C, 117°C, 118°C, 119°C, 122°C, 125°C, 128°C, etc., and more preferably 115°C to 120°C.

[0023] If the reaction temperature is too high, by-products will be produced, reducing the purity of the crude product and further reducing the yield of the product after distillation; if the reaction temperature is too low, the reaction will be incomplete and the yield will be reduced.

[0024] Preferably, the reaction time of the reaction in step (1) is 2 to 8 hours, for example, 3 hours, 4 hours, 5 hours, 5.25 hours, 5.5 hours, 5.75 hours, 6 hours, 7 hours, etc., more preferably 5 to 6 hours.

[0025] If the reaction time is too long, by-products will be produced, reducing the purity of the crude product and further reducing the yield of the product after distillation; if the reaction time is too short, the reaction is incomplete and the yield is reduced.

[0026] Preferably, the molar ratio of dimethyl carbonate to di-tert-butyl dicarbonate is (1.05-2.0):1, for example, it can be 1.1:1, 1.2:1, 1.25:1, 1.3:1, 1.35:1, 1.4:1, 1.45:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, etc., and is more preferably (1.2-1.5):1.

[0027] If the molar ratio of dimethyl carbonate to di-tert-butyl dicarbonate is too large, the dimethyl carbonate content in the crude product increases and the product yield after distillation decreases; if the molar ratio of dimethyl carbonate to di-tert-butyl dicarbonate is too small, the reaction cannot be fully carried out and the yield decreases.

[0028] Preferably, the temperature for adding the dimethyl carbonate in step (2) is 70°C to 100°C, for example, it can be 72°C, 74°C, 76°C, 78°C, 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C, 96°C, 98°C, etc., more preferably 80°C to 90°C.

[0029] Preferably, the reaction temperature in step (2) is 70°C to 100°C, for example, it can be 72°C, 74°C, 76°C, 78°C, 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C, 96°C, 98°C, etc., and more preferably 80°C to 90°C.

[0030] If the reaction temperature is too high, by-products will be produced, reducing the purity of the crude product and further reducing the yield of the product after distillation; if the reaction temperature is too low, the reaction will be incomplete and the yield will be reduced.

[0031] In the present invention, the temperature for adding dimethyl carbonate in step (2) and the temperature for the reaction may be the same or different.

[0032] Preferably, the reaction time of the reaction in step (2) is 3 to 9 hours, for example, it can be 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, 8.5 hours, etc., and more preferably 5 to 7 hours.

[0033] If the reaction time is too long, by-products will be produced, reducing the purity of the crude product and further reducing the yield of the product after distillation; if the reaction time is too short, the reaction is incomplete and the yield is reduced.

[0034] Preferably, step (2) further includes a post-treatment step after the reaction, and the post-treatment method includes: vacuum filtration, liquid separation, and distillation purification.

[0035] Preferably, the vacuum degree of the vacuum filtration in step (2) is 5-20 mbar, for example, 7 mbar, 9 mbar, 11 mbar, 13 mbar, 15 mbar, 17 mbar, 19 mbar, etc.

[0036] Preferably, the separation method comprises: adding an acidic substance to the filtrate obtained after vacuum filtration, adjusting the pH of the filtrate to 6.5-7.5, and then separating the liquids, where 6.5-7.5 can be, for example, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, etc.

[0037] Preferably, the acidic substance includes any one of dilute hydrochloric acid, dilute sulfuric acid, and dilute acetic acid, or a combination of at least two of them.

[0038] Preferably, the distillation in step (2) is atmospheric distillation at a temperature of 110°C to 140°C, for example, 112°C, 114°C, 116°C, 118°C, 120°C, 122°C, 124°C, 126°C, 128°C, 130°C, 132°C, 134°C, 136°C, 138°C, etc., more preferably 115°C to 125°C.

[0039] Preferably, the preparation method specifically comprises the following steps:

[0040] (1) in the presence of a catalyst, di-tert-butyl dicarbonate and trifluoroethanol are mixed and reacted at 110° C. to 130° C. for 2 to 8 hours to obtain the intermediate product;

[0041] The molar ratio of trifluoroethanol to di-tert-butyl dicarbonate is (2.0-2.8):1, and the mass ratio of the catalyst to di-tert-butyl dicarbonate is (0.1-0.25):1;

[0042]

[0043] (2) adding dimethyl carbonate to the reaction system of step (1) at 70° C. to 100° C., reacting at 70° C. to 100° C. for 3 to 9 hours, cooling to 20° C. to 30° C., and vacuum filtering at a vacuum degree of 5 to 20 mbar to obtain a filtrate, adding an acidic substance to the filtrate, adjusting the pH of the filtrate to 6.5 to 7.5, separating the liquids, and rectifying at 110° C. to 140° C. to obtain the methyl trifluoroethyl carbonate;

[0044] Wherein, the molar ratio of dimethyl carbonate to di-tert-butyl dicarbonate is (1.05-2.0):1;

[0045]

[0046] In the present invention, the catalyst in the reaction of step (2) refers to the catalyst added in step (1).

[0047] Preferably, the preparation method specifically comprises the following steps:

[0048] (1) in the presence of a catalyst, di-tert-butyl dicarbonate and trifluoroethanol are mixed and reacted at 115° C. to 120° C. for 5 to 6 hours to obtain the intermediate product;

[0049] The molar ratio of trifluoroethanol to di-tert-butyl dicarbonate is (2.1-2.3):1, and the mass ratio of the catalyst to di-tert-butyl dicarbonate is (0.15-0.18):1;

[0050] (2) adding dimethyl carbonate to the reaction system of step (1) at 80° C. to 90° C., reacting at 80° C. to 90° C. for 5 to 7 hours, cooling to 20° C. to 30° C., and vacuum filtering at a vacuum degree of 5 to 20 mbar to obtain a filtrate, adding an acidic substance to the filtrate, adjusting the pH of the filtrate to 6.5 to 7.5, separating the liquids, and rectifying at 115° C. to 125° C. to obtain the methyl trifluoroethyl carbonate;

[0051] Wherein, the molar ratio of dimethyl carbonate to di-tert-butyl dicarbonate is (1.2-1.5):1.

[0052] Compared with the prior art, the present invention has at least the following beneficial effects:

[0053] The preparation method of the present invention has few reaction steps, high selectivity and high yield. Compared with the existing synthesis method, the synthesis raw material of the present invention is di-tert-butyl dicarbonate, which avoids the use of highly toxic raw materials such as methyl chloroformate, and is green and environmentally friendly. Methanol that will form a ternary azeotropic reaction with the product FEMC and dimethyl carbonate during distillation is not generated in the reaction system, thereby improving the product purity. In addition, the reaction product carbon dioxide in step (2) of the present invention will escape, promote the reaction to proceed in the forward direction, and improve the reaction yield. DETAILED DESCRIPTION

[0054] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0055] Example 1

[0056] This embodiment provides a method for preparing methyl trifluoroethyl carbonate, the preparation method comprising the following steps:

[0057] (1) Add 0.5 mol of di-tert-butyl dicarbonate, 1.05 mol of trifluoroethanol, and 0.303 mol of sodium methoxide to a 500 mL bottle, stir thoroughly, quickly heat to 115°C, and keep warm for 5 hours;

[0058] (2) Cooling to 80°C, adding 0.6 mol of dimethyl carbonate, keeping the temperature for reaction for 5 h, cooling to room temperature, vacuum filtering, collecting the filtrate, neutralizing the filtrate with dilute hydrochloric acid to pH 7, then separating the liquids, and distilling the organic phase at 120°C under normal pressure to obtain methyl trifluoroethyl carbonate.

[0059] Example 2

[0060] A method for preparing methyl trifluoroethyl carbonate, which differs from Example 1 only in that 0.303 mol of sodium methoxide is replaced by 0.41 mol of sodium hydroxide, and other conditions and parameters are the same as those in Example 1.

[0061] Example 3

[0062] This embodiment provides a method for preparing methyl trifluoroethyl carbonate, the preparation method comprising the following steps:

[0063] (1) Add 0.5 mol of di-tert-butyl dicarbonate, 1.15 mol of trifluoroethanol, and 0.303 mol of sodium methoxide to a 500 mL bottle, stir thoroughly, quickly heat to 115°C, and keep warm for 5 hours;

[0064] (2) Cooling to 80°C, adding 0.75 mol of dimethyl carbonate, keeping the temperature for reaction for 5 h, cooling to room temperature, vacuum filtering, collecting the filtrate, neutralizing the filtrate with dilute hydrochloric acid to pH 7, then separating the liquids, and distilling the organic phase at 120°C under normal pressure to obtain methyl trifluoroethyl carbonate.

[0065] Example 4

[0066] This embodiment provides a method for preparing methyl trifluoroethyl carbonate, which comprises the following steps:

[0067] (1) Add 0.5 mol of di-tert-butyl dicarbonate, 1.1 mol of trifluoroethanol, and 0.303 mol of sodium methoxide into a 500 mL bottle, stir thoroughly, quickly heat to 120°C, and keep warm for 5 hours;

[0068] (2) Cooling to 90°C, adding 0.7 mol of dimethyl carbonate, keeping the temperature for reaction for 5 h, cooling to room temperature, vacuum filtering, collecting the filtrate, neutralizing the filtrate with dilute hydrochloric acid to pH 7, then separating the liquids, and distilling the organic phase at 120°C under normal pressure to obtain methyl trifluoroethyl carbonate.

[0069] Example 5

[0070] This embodiment provides a method for preparing methyl trifluoroethyl carbonate, the preparation method comprising the following steps:

[0071] (1) Add 0.5 mol of di-tert-butyl dicarbonate, 1.05 mol of trifluoroethanol, and 0.303 mol of sodium methoxide to a 500 mL bottle, stir thoroughly, quickly heat to 118°C, and keep warm for 6 hours;

[0072] (2) Cooling to 80°C, adding 0.65 mol of dimethyl carbonate, keeping the temperature for reaction for 7 hours, cooling to room temperature, vacuum filtering, collecting the filtrate, neutralizing the filtrate with dilute hydrochloric acid to pH 7, then separating the liquids, and distilling the organic phase at 120°C under normal pressure to obtain methyl trifluoroethyl carbonate.

[0073] Example 6

[0074] This embodiment provides a method for preparing methyl trifluoroethyl carbonate, the preparation method comprising the following steps:

[0075] (1) Add 0.5 mol of di-tert-butyl dicarbonate, 1.05 mol of trifluoroethanol, and 0.3636 mol of sodium methoxide to a 500 mL bottle, stir thoroughly, quickly heat to 115°C, and keep warm for 6 hours;

[0076] (2) Cooling to 85°C, adding 0.65 mol of dimethyl carbonate, keeping the temperature for reaction for 5 h, cooling to room temperature, vacuum filtering, collecting the filtrate, neutralizing the filtrate with dilute hydrochloric acid to pH 7, then separating the liquids, and distilling the organic phase at 120°C under normal pressure to obtain methyl trifluoroethyl carbonate.

[0077] Example 7

[0078] This embodiment provides a method for preparing methyl trifluoroethyl carbonate, the preparation method comprising the following steps:

[0079] (1) Add 0.5 mol of di-tert-butyl dicarbonate, 1.0 mol of trifluoroethanol, and 0.303 mol of sodium methoxide into a 500 mL bottle, stir thoroughly, quickly heat to 120°C, and keep warm for 5 hours;

[0080] (2) Cooling to 85°C, adding 0.5 mol of dimethyl carbonate, keeping the temperature for reaction for 7 hours, cooling to room temperature, vacuum filtering, collecting the filtrate, neutralizing the filtrate with dilute hydrochloric acid to pH 7, then separating the liquids, and distilling the organic phase at 120°C under normal pressure to obtain methyl trifluoroethyl carbonate.

[0081] Example 8

[0082] This embodiment provides a method for preparing methyl trifluoroethyl carbonate, the preparation method comprising the following steps:

[0083] (1) Add 0.5 mol of di-tert-butyl dicarbonate, 1.4 mol of trifluoroethanol, and 0.5 mol of sodium methoxide into a 500 mL bottle, stir thoroughly, quickly heat to 115°C, and keep warm for 6 hours;

[0084] (2) Cooling to 80°C, adding 0.6 mol of dimethyl carbonate, keeping the temperature for reaction for 7 hours, cooling to room temperature, vacuum filtering, collecting the filtrate, neutralizing the filtrate with dilute hydrochloric acid to pH 7, then separating the liquids, and distilling the organic phase at 120°C under normal pressure to obtain methyl trifluoroethyl carbonate.

[0085] Example 9

[0086] This embodiment provides a method for preparing methyl trifluoroethyl carbonate, which comprises the following steps:

[0087] (1) Add 0.5 mol of di-tert-butyl dicarbonate, 1.05 mol of trifluoroethanol, and 0.21 mol of sodium methoxide to a 500 mL bottle, stir thoroughly, quickly heat to 110°C, and keep warm for 2 hours;

[0088] (2) Cooling to 70°C, adding 0.525 mol of dimethyl carbonate, keeping the temperature for reaction for 3 h, cooling to room temperature, vacuum filtering, collecting the filtrate, neutralizing the filtrate with dilute hydrochloric acid to pH 7, then separating the liquids, and distilling the organic phase at 120°C under normal pressure to obtain methyl trifluoroethyl carbonate.

[0089] Example 10

[0090] This embodiment provides a method for preparing methyl trifluoroethyl carbonate, which comprises the following steps:

[0091] (1) Add 0.5 mol of di-tert-butyl dicarbonate, 1.05 mol of trifluoroethanol, and 0.3232 mol of sodium methoxide to a 500 mL bottle, stir thoroughly, quickly heat to 110°C, and keep warm for 2 hours;

[0092] (2) Cooling to 70°C, adding 0.525 mol of dimethyl carbonate, keeping the temperature for reaction for 3 h, cooling to room temperature, vacuum filtering, collecting the filtrate, neutralizing the filtrate with dilute hydrochloric acid to pH 7, then separating the liquids, and distilling the organic phase at 120°C under normal pressure to obtain methyl trifluoroethyl carbonate.

[0093] Embodiment 11

[0094] A method for preparing methyl trifluoroethyl carbonate, which differs from Example 1 only in that the amount of trifluoroethanol added is 1.5 mol, and other conditions and parameters are the same as those in Example 1.

[0095] Example 12

[0096] A method for preparing methyl trifluoroethyl carbonate, which differs from Example 1 only in that the amount of dimethyl carbonate added is 1.5 mol, and other conditions and parameters are the same as those in Example 1.

[0097] Embodiment 13

[0098] A method for preparing methyl trifluoroethyl carbonate, which differs from Example 1 only in that the amount of sodium methoxide added is 0.6 mol, and other conditions and parameters are the same as those in Example 1.

[0099] Comparative Example 1

[0100] A method for preparing methyl trifluoroethyl carbonate, which differs from Example 1 only in that sodium methoxide is not added, and other conditions and parameters are the same as those in Example 1.

[0101] Comparative Example 2

[0102] This comparative example provides a method for preparing methyl trifluoroethyl carbonate, which comprises the following steps:

[0103] (1) Add 0.5 mol of di-tert-butyl dicarbonate, 1.05 mol of trifluoroethanol, 0.6 mol of dimethyl carbonate, and 0.303 mol of sodium methoxide into a 500 mL bottle, stir well, quickly heat to 115° C., keep the temperature for 10 hours, cool to room temperature, vacuum filter, collect the filtrate, neutralize the filtrate with dilute hydrochloric acid to neutrality, then separate the liquids, and distill the organic phase at 120° C. under normal pressure to obtain methyl trifluoroethyl carbonate.

[0104] Comparative Example 3

[0105] This comparative example provides a method for preparing methyl trifluoroethyl carbonate, which comprises the following steps:

[0106] (1) Add 1.05 mol of trifluoroethanol, 1.2 mol of dimethyl carbonate, and 0.303 mol of sodium methoxide into a 500 mL bottle, stir thoroughly, quickly heat to 80°C, keep warm for 5 hours, cool to room temperature, vacuum filter, collect the filtrate, neutralize the filtrate with dilute hydrochloric acid to neutrality, then separate the liquids, and distill the organic phase at 120°C under normal pressure to obtain methyl trifluoroethyl carbonate.

[0107] Test Method

[0108] The purity and molar yield of the product were tested by gas chromatography, and the ratio of the actual product mole number to the theoretical product mole number was the molar yield of the product.

[0109] Test Results

[0110] The test results are shown in Table 1.

[0111] Table 1

[0112] Molar yield (%) purity(%) Example 1 94.2 99.95 Example 2 85.3 99.98 Example 3 94.5 99.96 Example 4 92.3 99.97 Example 5 93.4 99.95 Example 6 91.6 99.97 Example 7 85.4 99.95 Example 8 83.2 99.96 Example 9 90.4 99.94 Example 10 92.1 99.96 Embodiment 11 92.1 99.97 Example 12 87.5 99.94 Example 13 92.5 99.94 Comparative Example 1 15.3 99.94 Comparative Example 2 54.6 99.92 Comparative Example 3 72.6 99.95

[0113] The test results show that:

[0114] (1) It can be seen from Examples 1 to 13 that the method for preparing methyl trifluoroethyl carbonate provided by the present invention has fewer reaction steps and high product purity and yield.

[0115] (2) By comparing Example 1 with Example 11, it can be seen that if the molar ratio of trifluoroethanol to di-tert-butyl dicarbonate is too large, the trifluoroethanol content in the crude product increases and the product yield after distillation decreases.

[0116] (3) By comparing Example 1 with Example 12, it can be seen that if the molar ratio of dimethyl carbonate to di-tert-butyl dicarbonate is too large, the dimethyl carbonate content in the crude product increases, the product purity decreases, and the product yield decreases.

[0117] (4) By comparing Example 1 with Example 13, it can be seen that if the mass ratio of the catalyst to di-tert-butyl dicarbonate is too large, not only will the yield not be improved, but also the catalyst will be wasted.

[0118] (5) It can be seen from Example 1 and Comparative Example 1 that the present invention can achieve a higher yield by adding a catalyst.

[0119] (6) It can be seen from Example 1 and Comparative Example 2 that the present invention can obtain a higher yield through a two-step reaction.

[0120] (7) It can be seen from Example 1 and Comparative Example 3 that the reaction of Comparative Example 3 generates methanol, and methanol, dimethyl carbonate, and methyl trifluoroethyl carbonate easily form a ternary azeotrope, which reduces the purity of the crude product and further reduces the product yield after distillation. The present invention adds di-tert-butyl dicarbonate to the reaction system and performs a two-step reaction. During distillation, no ternary azeotrope occurs, thereby improving the purity of the crude product and the product yield after distillation. In addition, the reaction product carbon dioxide in step (2) of the present invention will escape, which promotes the forward reaction and improves the reaction yield. The present invention can obtain a higher yield.

[0121] In summary, the present invention provides a method for preparing methyl trifluoroethyl carbonate, the preparation method comprising the following steps:

[0122] (1) reacting di-tert-butyl dicarbonate and trifluoroethanol to obtain an intermediate product;

[0123] (2) adding dimethyl carbonate to the reaction system of step (1), reacting to obtain methyl trifluoroethyl carbonate;

[0124] The reaction in step (1) is carried out in the presence of a catalyst.

[0125] The preparation method of the present invention has fewer reaction steps and high product purity and yield. Compared with the existing synthesis method, the synthesis raw material of the present invention is di-tert-butyl dicarbonate, and methanol that will form a ternary azeotropic reaction with the product FEMC and dimethyl carbonate when no distillation is generated in the reaction system, thereby improving the purity of the crude product. In addition, the reaction product carbon dioxide in step (2) of the present invention will escape, which promotes the forward reaction and improves the reaction yield.

[0126] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing methyl trifluoroethyl carbonate, characterized in that: The preparation method comprises the following steps: (1) reacting di-tert-butyl dicarbonate and trifluoroethanol to obtain an intermediate product; (2) adding dimethyl carbonate to the reaction system of step (1), reacting to obtain methyl trifluoroethyl carbonate; The reaction in step (1) is carried out in the presence of a catalyst.

2. The preparation method according to claim 1, characterized in that: The molar ratio of trifluoroethanol to di-tert-butyl dicarbonate is (2.0-2.8):1, preferably (2.1-2.3):

1.

3. The preparation method according to claim 1 or 2, characterized in that: The catalyst comprises any one of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, sodium methoxide, sodium ethoxide, or a combination of at least two thereof, preferably sodium methoxide and / or sodium hydroxide; Preferably, the mass ratio of the catalyst to di-tert-butyl dicarbonate is (0.1-0.25):1, preferably (0.15-0.18):

1.

4. The preparation method according to any one of claims 1 to 3, characterized in that The reaction temperature in step (1) is 110°C to 130°C, preferably 115°C to 120°C; Preferably, the reaction time of step (1) is 2 to 8 hours, preferably 5 to 6 hours.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The molar ratio of dimethyl carbonate to di-tert-butyl dicarbonate is (1.05-2.0):1, preferably (1.2-1.5):

1.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The temperature for adding the dimethyl carbonate in step (2) is 70°C to 100°C, preferably 80°C to 90°C.

7. The preparation method according to any one of claims 1 to 6, characterized in that The reaction temperature in step (2) is 70°C to 100°C, preferably 80°C to 90°C; Preferably, the reaction time of the reaction in step (2) is 3 to 9 hours, preferably 5 to 7 hours.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The step (2) further comprises a post-treatment step after the reaction, and the post-treatment method comprises: vacuum filtration, liquid separation, and distillation purification.

9. The preparation method according to claim 8, characterized in that: The vacuum degree of the vacuum filtration in step (2) is 5-20 mbar; Preferably, the liquid separation method comprises: adding an acidic substance to the filtrate obtained after vacuum filtration, adjusting the pH of the filtrate to 6.5-7.5, and then separating the liquids; Preferably, the distillation in step (2) is atmospheric distillation at a temperature of 110°C to 140°C, preferably 115°C to 125°C.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The preparation method specifically comprises the following steps: (1) in the presence of a catalyst, di-tert-butyl dicarbonate and trifluoroethanol are mixed and reacted at 110° C. to 130° C. for 2 to 8 hours to obtain the intermediate product; The molar ratio of trifluoroethanol to di-tert-butyl dicarbonate is (2.0-2.8):1, and the mass ratio of the catalyst to di-tert-butyl dicarbonate is (0.1-0.25):1; (2) adding dimethyl carbonate to the reaction system of step (1) at 70° C. to 100° C., reacting at 70° C. to 100° C. for 3 to 9 hours, cooling to 20° C. to 30° C., and vacuum filtering at a vacuum degree of 5 to 20 mbar to obtain a filtrate, adding an acidic substance to the filtrate, adjusting the pH of the filtrate to 6.5 to 7.5, separating the liquids, and rectifying at 110° C. to 140° C. to obtain the methyl trifluoroethyl carbonate; Wherein, the molar ratio of dimethyl carbonate to di-tert-butyl dicarbonate is (1.05-2.0):1.

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