Synthesis method of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane

Abstract

The present invention discloses a method for synthesizing 1,2-dimethoxy-1,1,2,2-tetrafluoroethane, relating to the technical field of battery electrolyte additives. The method comprises the following steps: S1: introducing nitrogen into a four-necked flask equipped with a stirrer, a thermometer, and a condensation reflux device to displace the air inside the flask; then adding a solvent to the flask; turning on the stirrer and condensing water; and then sequentially adding 1,2-dihydroxy-1,1,2,2-tetrafluoroethane, methanol, and a catalyst to the flask to obtain a mixed solution A. The synthesis method of the present invention is relatively simple and suitable for industrial production. At the same time, the reaction process is simple, no intermediates are produced during the reaction process, and the reaction by-products are relatively small. Therefore, it is convenient to subsequently separate the reaction product to obtain 1,2-dimethoxy-1,1,2,2-tetrafluoroethane with high purity. The high-purity 1,2-dimethoxy-1,1,2,2-tetrafluoroethane is convenient for subsequent applications.

Description

Technical Field

[0001] The present invention relates to the technical field of battery electrolyte additives, in particular to a method for synthesizing 1,2-dimethoxy-1,1,2,2-tetrafluoroethane. Background Art

[0002] Improvements in lithium-ion battery technology in terms of efficiency and energy density have made it possible to be used in electric vehicles. However, for pure electric vehicles, its charging time is the main reason limiting its large-scale application. The factors limiting the fast charging performance of the battery are ranked by the continuous medium model. The poor transmission performance of the electrolyte is the main reason limiting its fast charging performance. The limitations of the electrolyte must be overcome in order to modify the fast charging performance. At the same time, a large number of studies have shown that organic substances containing methoxy groups can effectively improve the transmission performance of the electrolyte. Therefore, the use of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane as an electrolyte additive has appeared on the market. The dimethoxy group in 1,2-dimethoxy-1,1,2,2-tetrafluoroethane can not only effectively improve the transmission performance of the electrolyte, but also the outermost orbital of the fluorine electrons contained in it has 7 electrons, which has strong electronegativity and weak polarity. Fluorination will lower the freezing point of the solvent, increase the flash point, and improve the oxidation resistance, which helps to improve the contact performance between the electrolyte and the electrode. At the same time, it can effectively improve the high and low temperature performance and battery capacity performance of lithium batteries.

[0003] Currently, the Mitsunobu reaction is often used in the market to synthesize 1,2-dimethoxy-1,1,2,2-tetrafluoroethane. The reaction mechanism of the Mitsunobu reaction is quite complicated. First, triphenylphosphine attacks diethyl azodicarboxylate to form an intermediate and captures the proton of the carboxylic acid or other nucleophilic reagent. The alcohol attacks the phosphine cation center to form an oxide ion, and the diethyl azodicarboxylate falls off to form a hydrazine by-product. The nucleophilic reagent reversely attacks the alkoxyphosphine intermediate to generate the product and the triphenylphosphine oxide by-product. The reaction process generates a variety of intermediates and reaction by-products, making it difficult to separate the reaction products after the reaction is completed, which in turn affects the purity of the reaction products and is inconvenient for their subsequent use. Therefore, a method for synthesizing 1,2-dimethoxy-1,1,2,2-tetrafluoroethane is proposed. Summary of the Invention

[0004] The object of the present invention is to provide a method for synthesizing 1,2-dimethoxy-1,1,2,2-tetrafluoroethane to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for synthesizing 1,2-dimethoxy-1,1,2,2-tetrafluoroethane, the synthesis steps of which are as follows:

[0006] S1: nitrogen is introduced into a four-necked flask equipped with a stirrer, a thermometer, and a condensation reflux device to replace the air inside the flask, and then the solvent is added to the flask. After turning on the stirrer and condensing water, 1,2-dihydroxy-1,1,2,2-tetrafluoroethane, methanol, and the catalyst are added to the flask in sequence to obtain a mixed solution A;

[0007] S2: heating the mixed solution A to 80-90°C and reacting for 3-5 hours to obtain reaction solution B;

[0008] S3: Lowering the temperature of reaction solution B to 60-70° C., then adding sodium hydroxide solution to reaction solution B in 3-5 portions according to a certain ratio, with the addition interval of sodium hydroxide solution being 30-60 minutes. After all the sodium hydroxide solution is added, the mixture is kept at a constant temperature for 1-2 hours to obtain reaction solution C;

[0009] S4: Filter the reaction solution C to remove solid matter, repeatedly wash the filtrate with distilled water at 60-70°C for 3-5 times, let it stand and separate the layers to obtain an organic solution D;

[0010] S5: performing reduced pressure distillation on the organic solution D to recover the solvent to obtain a crude product E, and performing recrystallization on the crude product E to obtain a finished product 1,2-dimethoxy-1,1,2,2-tetrafluoroethane.

[0011] Furthermore, in step S1, the molar ratio of 1,2-dihydroxy-1,1,2,2-tetrafluoroethane to methanol is 1:2-1:3.

[0012] Furthermore, in step S1, the mass ratio of 1,2-dihydroxy-1,1,2,2-tetrafluoroethane to the catalyst is 100:1-100:10, and the catalyst is a mixture of one or more of aluminum oxide, magnesium oxide and zeolite, and the particle diameter of the catalyst is 800 mesh to 1000 mesh.

[0013] Furthermore, in step S1, the mass ratio of 1,2-dihydroxy-1,1,2,2-tetrafluoroethane to the solvent is 1:1-1:10, and the solvent is a mixture of one or more of anhydrous benzene, dimethylformamide and hexamethylphosphoric triamide.

[0014] Furthermore, the mass ratio of the sodium hydroxide solution to 1,2-dihydroxy-1,1,2,2-tetrafluoroethane added in step S3 is 1:1-3:1, and the concentration of the sodium hydroxide solution is 30%-50%.

[0015] Furthermore, in step S5, the temperature of the reduced pressure distillation is 150-200° C., and the pressure of the reduced pressure distillation is 2000-3000 Pa.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The synthesis method of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane is relatively simple and suitable for industrial production. At the same time, the reaction process is simple, no intermediates are produced during the reaction process, and the reaction by-products are relatively small. Therefore, it is convenient to subsequently separate the reaction products to obtain 1,2-dimethoxy-1,1,2,2-tetrafluoroethane with high purity. The high-purity 1,2-dimethoxy-1,1,2,2-tetrafluoroethane is convenient for subsequent application. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] Example 1:

[0020] The synthesis method of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane comprises the following steps:

[0021] S1: Nitrogen was introduced into a four-necked flask equipped with a stirrer, a thermometer, and a condensation reflux device to replace the air inside the flask. 300 g of solvent was then added to the flask. After turning on the stirrer and condensing the water, 134 g of 1,2-dihydroxy-1,1,2,2-tetrafluoroethane, 64 g of methanol, and 6.7 g of catalyst were added to the flask in sequence to obtain a mixed solution A, wherein the solvent was anhydrous benzene and the catalyst was zeolite with a particle diameter of 800 mesh.

[0022] S2: heating the mixed solution A to 80°C and reacting for 4 hours to obtain reaction solution B;

[0023] S3: Lowering the temperature of reaction solution B to 60° C., then adding 250 g of sodium hydroxide solution to reaction solution B in three portions, with a concentration of 40% and an addition interval of 30 minutes. After all the sodium hydroxide solution has been added, the mixture is kept at a constant temperature for 1 hour to obtain reaction solution C;

[0024] S4: Filter the reaction solution C to remove solid matter, repeatedly wash the filtrate with distilled water at 65°C for 3 times, let it stand and separate the layers to obtain an organic solution D;

[0025] S5: The organic solution D was subjected to vacuum distillation to recover the solvent to obtain a crude product E. The vacuum distillation temperature was 150° C. and the vacuum distillation pressure was 2500 Pa. The crude product E was recrystallized to obtain 142.6 g of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane as a finished product. The synthesis rate was 88%, and the purity was 98.3% as measured by infrared spectroscopy.

[0026] Example 2:

[0027] The synthesis method of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane comprises the following steps:

[0028] S1: Nitrogen was introduced into a four-necked flask equipped with a stirrer, a thermometer, and a condensation reflux device to replace the air inside the flask. 300 g of solvent was then added to the flask. After turning on the stirrer and condensing the water, 134 g of 1,2-dihydroxy-1,1,2,2-tetrafluoroethane, 80 g of methanol, and 6.7 g of catalyst were added to the flask in sequence to obtain a mixed solution A, wherein the solvent was anhydrous benzene and the catalyst was zeolite with a particle diameter of 800 mesh.

[0029] S2: heating the mixed solution A to 80°C and reacting for 4 hours to obtain reaction solution B;

[0030] S3: Lowering the temperature of reaction solution B to 60° C., then adding 250 g of sodium hydroxide solution to reaction solution B in three portions, with a concentration of 40% and an addition interval of 30 minutes. After all the sodium hydroxide solution has been added, the mixture is kept at a constant temperature for 1 hour to obtain reaction solution C;

[0031] S4: Filter the reaction solution C to remove solid matter, repeatedly wash the filtrate with distilled water at 65°C for 3 times, let it stand and separate the layers to obtain an organic solution D;

[0032] S5: The organic solution D was subjected to vacuum distillation to recover the solvent to obtain a crude product E. The vacuum distillation temperature was 150° C. and the vacuum distillation pressure was 2500 Pa. The crude product E was recrystallized to obtain 145.8 g of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane as a finished product. The synthesis rate was 90%, and the purity was 98.4% as measured by infrared spectroscopy.

[0033] Example 3:

[0034] The synthesis method of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane comprises the following steps:

[0035] S1: Nitrogen was introduced into a four-necked flask equipped with a stirrer, a thermometer, and a condensation reflux device to replace the air inside the flask. 300 g of solvent was then added to the flask. After turning on the stirrer and condensing the water, 134 g of 1,2-dihydroxy-1,1,2,2-tetrafluoroethane, 64 g of methanol, and 13.4 g of catalyst were added to the flask in sequence to obtain a mixed solution A, wherein the solvent was anhydrous benzene and the catalyst was zeolite with a particle diameter of 800 mesh.

[0036] S2: heating the mixed solution A to 80°C and reacting for 4 hours to obtain reaction solution B;

[0037] S3: Lowering the temperature of reaction solution B to 60° C., then adding 250 g of sodium hydroxide solution to reaction solution B in three portions, with a concentration of 40% and an addition interval of 30 minutes. After all the sodium hydroxide solution has been added, the mixture is kept at a constant temperature for 1 hour to obtain reaction solution C;

[0038] S4: Filter the reaction solution C to remove solid matter, repeatedly wash the filtrate with distilled water at 65°C for 3 times, let it stand and separate the layers to obtain an organic solution D;

[0039] S5: The organic solution D was subjected to vacuum distillation to recover the solvent to obtain a crude product E. The vacuum distillation temperature was 150° C. and the vacuum distillation pressure was 2500 Pa. The crude product E was recrystallized to obtain 150.7 g of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane as a finished product. The synthesis rate was 93%, and the purity was 99.8% as measured by infrared spectroscopy.

[0040] Example 4:

[0041] The synthesis method of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane comprises the following steps:

[0042] S1: Nitrogen was introduced into a four-necked flask equipped with a stirrer, a thermometer, and a condensation reflux device to replace the air inside the flask, and then 300 g of solvent was added to the four-necked flask. After turning on the stirrer and condensing the water, 134 g of 1,2-dihydroxy-1,1,2,2-tetrafluoroethane, 64 g of methanol, and 6.7 g of catalyst were added to the four-necked flask in sequence to obtain a mixed solution A, wherein the solvent was a mixture of dimethylformamide and hexamethylphosphoric triamide in a volume ratio of 1:1, and the catalyst was a zeolite with a particle diameter of 800 mesh;

[0043] S2: heating the mixed solution A to 80°C and reacting for 4 hours to obtain reaction solution B;

[0044] S3: Lowering the temperature of reaction solution B to 60° C., then adding 250 g of sodium hydroxide solution to reaction solution B in three portions, with a concentration of 40% and an addition interval of 30 minutes. After all the sodium hydroxide solution has been added, the mixture is kept at a constant temperature for 1 hour to obtain reaction solution C;

[0045] S4: Filter the reaction solution C to remove solid matter, repeatedly wash the filtrate with distilled water at 65°C for 3 times, let it stand and separate the layers to obtain an organic solution D;

[0046] S5: The organic solution D was subjected to vacuum distillation to recover the solvent to obtain a crude product E. The vacuum distillation temperature was 170° C. and the vacuum distillation pressure was 2000 Pa. The crude product E was recrystallized to obtain 144.2 g of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane as a finished product. The synthesis rate was 89% and the purity was 99.5% as measured by infrared spectroscopy.

[0047] Embodiment 5:

[0048] The synthesis method of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane comprises the following steps:

[0049] S1: Nitrogen was introduced into a four-necked flask equipped with a stirrer, a thermometer, and a condensation reflux device to replace the air inside the flask, and then 300 g of solvent was added to the flask. After turning on the stirrer and condensing the water, 134 g of 1,2-dihydroxy-1,1,2,2-tetrafluoroethane, 64 g of methanol, and 6.7 g of catalyst were added to the flask in sequence to obtain a mixed solution A, wherein the solvent was anhydrous benzene and the catalyst was a mixture of aluminum oxide and magnesium oxide with a mass ratio of 1:1 and a particle diameter of 1000 mesh;

[0050] S2: heating the mixed solution A to 80°C and reacting for 4 hours to obtain reaction solution B;

[0051] S3: Lowering the temperature of reaction solution B to 60° C., then adding 250 g of sodium hydroxide solution to reaction solution B in three portions, with a concentration of 40% and an addition interval of 30 minutes. After all the sodium hydroxide solution has been added, the mixture is kept at a constant temperature for 1 hour to obtain reaction solution C;

[0052] S4: Filter the reaction solution C to remove solid matter, repeatedly wash the filtrate with distilled water at 65°C for 3 times, let it stand and separate the layers to obtain an organic solution D;

[0053] S5: The organic solution D was subjected to vacuum distillation to recover the solvent to obtain a crude product E. The vacuum distillation temperature was 150° C. and the vacuum distillation pressure was 2500 Pa. The crude product E was recrystallized to obtain 137.7 g of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane as a finished product. The synthesis rate was 85%, and the purity was 97.4% as measured by infrared spectroscopy.

[0054] Example 6:

[0055] The synthesis method of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane comprises the following steps:

[0056] S1: Nitrogen was introduced into a four-necked flask equipped with a stirrer, a thermometer, and a condensation reflux device to replace the air inside the flask. 300 g of solvent was then added to the flask. After turning on the stirrer and condensing the water, 134 g of 1,2-dihydroxy-1,1,2,2-tetrafluoroethane, 64 g of methanol, and 6.7 g of catalyst were added to the flask in sequence to obtain a mixed solution A, wherein the solvent was anhydrous benzene and the catalyst was zeolite with a particle diameter of 800 mesh.

[0057] S2: heating the mixed solution A to 90°C and reacting for 5 hours to obtain reaction solution B;

[0058] S3: Lowering the temperature of reaction solution B to 60° C., then adding 250 g of sodium hydroxide solution to reaction solution B in three portions, with a concentration of 40% and an addition interval of 30 minutes. After all the sodium hydroxide solution has been added, the mixture is kept at a constant temperature for 1 hour to obtain reaction solution C;

[0059] S4: Filter the reaction solution C to remove solid matter, repeatedly wash the filtrate with distilled water at 65°C for 3 times, let it stand and separate the layers to obtain an organic solution D;

[0060] S5: The organic solution D was subjected to vacuum distillation to recover the solvent to obtain a crude product E. The vacuum distillation temperature was 150° C. and the vacuum distillation pressure was 2500 Pa. The crude product E was recrystallized to obtain 149.0 g of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane as a finished product. The synthesis rate was 92%, and the purity was 98.3% as measured by infrared spectroscopy.

[0061] Embodiment seven:

[0062] The synthesis method of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane comprises the following steps:

[0063] S1: Nitrogen was introduced into a four-necked flask equipped with a stirrer, a thermometer, and a condensation reflux device to replace the air inside the flask. 300 g of solvent was then added to the flask. After turning on the stirrer and condensing the water, 134 g of 1,2-dihydroxy-1,1,2,2-tetrafluoroethane, 64 g of methanol, and 6.7 g of catalyst were added to the flask in sequence to obtain a mixed solution A, wherein the solvent was anhydrous benzene and the catalyst was zeolite with a particle diameter of 800 mesh.

[0064] S2: heating the mixed solution A to 80°C and reacting for 4 hours to obtain reaction solution B;

[0065] S3: Lowering the temperature of the reaction solution B to 65° C., then adding 300 g of sodium hydroxide solution to the reaction solution B in three portions, with a concentration of 50% and an addition interval of 30 minutes. After all the sodium hydroxide solution has been added, the mixture is kept at a constant temperature for 1 hour to obtain a reaction solution C.

[0066] S4: Filter the reaction solution C to remove solid matter, repeatedly wash the filtrate with distilled water at 65°C for 3 times, let it stand and separate the layers to obtain an organic solution D;

[0067] S5: The organic solution D was subjected to vacuum distillation to recover the solvent to obtain a crude product E. The vacuum distillation temperature was 150° C. and the vacuum distillation pressure was 2500 Pa. The crude product E was recrystallized to obtain 140.9 g of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane as a finished product. The synthesis rate was 87%, and the purity was 99.3% as measured by infrared spectroscopy.

[0068] Embodiment 8:

[0069] The synthesis method of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane comprises the following steps:

[0070] S1: Nitrogen was introduced into a four-necked flask equipped with a stirrer, a thermometer, and a condensation reflux device to replace the air inside the flask. 300 g of solvent was then added to the flask. After turning on the stirrer and condensing the water, 134 g of 1,2-dihydroxy-1,1,2,2-tetrafluoroethane, 64 g of methanol, and 6.7 g of catalyst were added to the flask in sequence to obtain a mixed solution A, wherein the solvent was anhydrous benzene and the catalyst was zeolite with a particle diameter of 800 mesh.

[0071] S2: heating the mixed solution A to 80°C and reacting for 4 hours to obtain reaction solution B;

[0072] S3: Lowering the temperature of reaction solution B to 60° C., then adding 250 g of sodium hydroxide solution to reaction solution B in three portions, with a concentration of 40% and an addition interval of 30 minutes. After all the sodium hydroxide solution has been added, the mixture is kept at a constant temperature for 1 hour to obtain reaction solution C;

[0073] S4: Filter the reaction solution C to remove solid matter, wash the filtrate repeatedly with distilled water at 60°C for 4 times, let it stand and separate the layers to obtain an organic solution D;

[0074] S5: The organic solution D was subjected to vacuum distillation to recover the solvent to obtain a crude product E. The vacuum distillation temperature was 150° C. and the vacuum distillation pressure was 2500 Pa. The crude product E was recrystallized to obtain 142.5 g of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane as a finished product. The synthesis rate was 88%, and the purity was 99.2% as measured by infrared spectroscopy.

[0075] Comparative Example:

[0076] The finished product of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane was synthesized by Mitsunobu reaction, and its purity was tested by infrared spectroscopy.

[0077] The purity of the finished 1,2-dimethoxy-1,1,2,2-tetrafluoroethane of Examples 1 to 8 was compared with the purity of the 1,2-dimethoxy-1,1,2,2-tetrafluoroethane of the comparative example. The comparison results are shown in Table 1:

[0078] project Synthesis rate (%) purity(%) Example 1 88 98.3 Example 2 90 98.4 Example 3 93 99.8 Example 4 89 99.5 Example 5 85 97.4 Example 6 92 98.3 Example 7 87 99.3 Example 8 88 99.2 Comparative Example 85 83.5

[0079] Table 1

[0080] Table 1 shows that the 1,2-dimethoxy-1,1,2,2-tetrafluoroethane synthesized by the method of the present invention not only has a high purity, but also has a high synthesis rate.

[0081] Practical Application:

[0082] The 1,2-dimethoxy-1,1,2,2-tetrafluoroethane obtained in Examples 1 to 8 and the comparative example was sequentially added as an electrolyte additive to the lithium battery electrolyte, with the electrolyte without 1,2-dimethoxy-1,1,2,2-tetrafluoroethane added as a blank example. The addition amount was 2% of the total mass of the electrolyte. At the same time, these electrolytes were used to produce lithium batteries with a capacity of 1000 mAh and tested.

[0083] 1. High temperature cycle life

[0084] The test should be carried out at an ambient temperature of 55℃±2℃. During the test, the capacity retention rate test is performed every 100 cycles, and the test is repeated from 1 to 100 cycles. The charge and discharge are placed for 60 minutes between charge and discharge until the discharge time of any 100th cycle is less than 3h. Then, another cycle is performed according to the regulations of the 100th cycle. If the discharge time is still less than 3h, the lithium battery life is considered to have ended, and the experiment is terminated at the same time. The test results are shown in Table 2:

[0085] project 100 times 200 times 300 times Example 1 92％ 82％ 70％ Example 2 90％ 79％ 68％ Example 3 95％ 86％ 73％ Example 4 94％ 85％ 72％ Example 5 89％ 80％ 65％ Example 6 90％ 80％ 65％ Example 7 93％ 81％ 70％ Example 8 93％ 83％ 70％ Comparative Example 85％ 75％ 62％ Blank example 78％ 65％ /

[0086] Table 2

[0087] It can be seen from Table 2 that the addition of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane can effectively improve the high-temperature cycle life of lithium batteries. At the same time, the improvement effect of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane with higher purity is more obvious.

[0088] 2. Fast charging performance

[0089] Before charging the lithium battery, first charge it at 0.2I t A is discharged to the termination voltage, and then at an ambient temperature of 23℃±2℃, the t A charging, when the lithium battery terminal voltage reaches the charging limit voltage, change to constant voltage charging until the charging current is less than or equal to 0.03I t A, at an ambient temperature of 23℃±2℃, 0.2I t A current to the termination voltage, and then 0.3I t A is charged, and then at an ambient temperature of 23℃ ± 2℃, the t A is discharged to the termination voltage and its capacitance is tested. This cycle is repeated ten times as one cycle, and a total of three cycles are tested. The capacitance retention rate is calculated in each cycle. The test results are shown in Table 3:

[0090] project Week 1 Week 2 Week 3 Example 1 92％ 88％ 85％ Example 2 92％ 88％ 84％ Example 3 95％ 93％ 86％ Example 4 95％ 93％ 86％ Example 5 90％ 85％ 80％ Example 6 90％ 84％ 79％ Example 7 93％ 90％ 86％ Example 8 93％ 90％ 85％ Comparative Example 90％ 85％ 72％ Blank example 85％ 75％ 65％

[0091] Table 3

[0092] Table 3 shows that 1,2-dimethoxy-1,1,2,2-tetrafluoroethane can effectively improve the fast charging performance of lithium batteries. At the same time, the higher the purity of 1,2-dimethoxy-1,1,2,2-tetrafluoroethane, the better the effect.

[0093] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for synthesizing 1,2-dimethoxy-1,1,2,2-tetrafluoroethane, characterized in that: The synthesis steps are as follows: S1: nitrogen is introduced into a four-necked flask equipped with a stirrer, a thermometer, and a condensation reflux device to replace the air inside the flask, and then the solvent is added to the flask. After turning on the stirrer and condensing water, 1,2-dihydroxy-1,1,2,2-tetrafluoroethane, methanol, and the catalyst are added to the flask in sequence to obtain a mixed solution A; S2: heating the mixed solution A to 80-90°C and reacting for 3-5 hours to obtain reaction solution B; S3: Lowering the temperature of reaction solution B to 60-70° C., then adding sodium hydroxide solution to reaction solution B in 3-5 portions according to a certain ratio, with the addition interval of sodium hydroxide solution being 30-60 minutes. After all the sodium hydroxide solution is added, the mixture is kept at a constant temperature for 1-2 hours to obtain reaction solution C; S4: Filter the reaction solution C to remove solid matter, repeatedly wash the filtrate with distilled water at 60-70°C for 3-5 times, let it stand and separate the layers to obtain an organic solution D; S5: The organic solution D is subjected to reduced pressure distillation to recover the solvent to obtain a crude product E, and the crude product E is recrystallized to obtain the finished product 1,2-dimethoxy-1,1,2,2-tetrafluoroethane. The catalyst is a mixture of one or more of aluminum oxide, magnesium oxide and zeolite, and the particle diameter of the catalyst is 800-1000 mesh. The solvent is one or a mixture of more than one of anhydrous benzene, dimethylformamide and hexamethylphosphoric triamide.

2. The method for synthesizing 1,2-dimethoxy-1,1,2,2-tetrafluoroethane according to claim 1, characterized in that: In step S1, the molar ratio of 1,2-dihydroxy-1,1,2,2-tetrafluoroethane to methanol is 1:2-1:

3.

3. The method for synthesizing 1,2-dimethoxy-1,1,2,2-tetrafluoroethane according to claim 1, characterized in that: In step S1, the mass ratio of 1,2-dihydroxy-1,1,2,2-tetrafluoroethane to the catalyst is 100:1-100:

10.

4. The method for synthesizing 1,2-dimethoxy-1,1,2,2-tetrafluoroethane according to claim 1, characterized in that: In step S1, the mass ratio of 1,2-dihydroxy-1,1,2,2-tetrafluoroethane to the solvent is 1:1-1:

10.

5. The method for synthesizing 1,2-dimethoxy-1,1,2,2-tetrafluoroethane according to claim 1, characterized in that: The mass ratio of the sodium hydroxide solution to 1,2-dihydroxy-1,1,2,2-tetrafluoroethane added in step S3 is 1:1-3:1, and the concentration of the sodium hydroxide solution is 30%-50%.

6. The method for synthesizing 1,2-dimethoxy-1,1,2,2-tetrafluoroethane according to claim 1, characterized in that: The temperature of the reduced pressure distillation in step S5 is 150-200° C., and the pressure of the reduced pressure distillation is 2000-3000 Pa.