Purification method of 1, 2, 3-tri (cyanoethoxy) propane

Abstract

The invention discloses a purification method of 1, 2, 3-tri (cyanoethoxy) propane, which specifically comprises the following steps: A1, mixing a 1, 2, 3-tri (cyanoethoxy) propane crude product, an impurity removal reagent and an organic solvent, and reacting for 0.5-12 hours to form a reaction liquid, the 1, 2, 3-tri (cyanoethoxy) propane crude product contains 0.5-5% of dinitrile impurities, and the organic solvent contains 1-5% of organic solvent; the impurity removal reagent is selected from at least one of an anhydride compound, halogenated sulfonic acid, halogenated phosphoric acid or an acyl halide compound; and A2, the reaction liquid is neutralized with an alkali solution, washing and desalting are carried out, distillation is carried out, a 1, 2, 3-tri (cyanoethoxy) propane product is obtained, the purity of the 1, 2, 3-tri (cyanoethoxy) propane product is larger than 99.9%, and the content of dinitrile impurities is lower than 0.1%. The purification method disclosed by the invention is simple in process, high in purification yield and suitable for industrial application, and the obtained product is high in purity and is used as an electrolyte additive of a lithium ion battery.

Description

Technical Field

[0001] The present invention relates to the synthesis of additives for lithium-ion battery electrolytes, and particularly to a purification method of 1,2,3-tris(cyanoethoxy)propane. Background Art

[0002] As additives for lithium-ion battery electrolytes, nitrile compounds can effectively improve the high-temperature cycling and storage performance of lithium batteries. Through research, it has been found that the nitrile additive 1,2,3-tris(cyanoethoxy)propane has excellent performance in terms of capacity retention and high-temperature storage performance, and has good application prospects.

[0003] The prior art mainly uses glycerol and acrylonitrile as raw materials to prepare 1,2,3-tris(cyanoethoxy)propane. After purification, the purity of 1,2,3-tris(cyanoethoxy)propane is greater than 95%, and usually contains 0.5% - 5% of dinitrile impurities.

[0004] The dinitrile impurities in the 1,2,3-tris(cyanoethoxy)propane product are compounds represented by Structural Formula I or Structural Formula II.

[0005]

[0006] When 1,2,3-tris(cyanoethoxy)propane is used as an additive for lithium-ion battery electrolytes, since the dinitrile impurities contain proton hydrogen, and proton hydrogen is a key index to be strictly controlled in the production process of lithium-ion battery electrolytes. Proton hydrogen will cause the acidity of the electrolyte to increase, the decomposition of lithium salts, the discoloration of the electrolyte, resulting in gas generation in the battery, an increase in internal resistance, and a decrease in the capacity of the battery core. The cycling performance and safety performance of the battery will both decrease. Especially when 1,2,3-tris(cyanoethoxy)propane is used in a high-voltage battery system, at high voltage, the deterioration effect of proton hydrogen on the battery will be further aggravated. Usually, the dinitrile impurities in 1,2,3-tris(cyanoethoxy)propane need to be controlled below 0.1%. Therefore, it is very important to find a purification process that can effectively reduce the dinitrile impurities in 1,2,3-tris(cyanoethoxy)propane.

[0007] No method for removing dinitrile impurities in 1,2,3-tris(cyanoethoxy)propane has been found in the prior art.

[0008] European Patent EP2505622A discloses a method for preparing 1,2,3-tris(cyanoethoxy)propane by reacting glycerol and acrylonitrile at room temperature in a toluene solvent under the action of potassium hydroxide. The reactants are separated by organic phase, dried, and concentrated to obtain the product, with a yield of 95%, and no purification is carried out, and the purity is unknown.

[0009] Korean Patent KR20150105790A discloses a method for preparing 1,2,3-tris(cyanoethoxy)propane by reacting glycerol and acrylonitrile at room temperature in xylene solvent under the action of potassium hydroxide. The reactants are washed with water, dried, and the solvent is removed under vacuum to obtain the product with a yield of 92%. No purification is carried out and the purity is unknown.

[0010] The article "New Journal of Chemistry 2015, 39(12), 9155 - 9161" reports a method for preparing 1,2,3-tris(cyanoethoxy)propane by reacting glycerol and acrylonitrile at room temperature under the action of sodium hydroxide. The product is obtained by column chromatography purification with a yield of 80% and a GC purity of 99.9%. However, the method of column chromatography purification has high cost and low efficiency and is difficult to be used in industrial production.

[0011] Chinese Patent CN103562177A discloses a method for preparing 1,2,3-tris(cyanoethoxy)propane by reacting glycerol and acrylonitrile at 40 °C under the action of potassium tert-butoxide. The reactants are dissolved in dichloromethane, washed with water, and then concentrated and distilled under reduced pressure to obtain 1,2,3-tris(cyanoethoxy)propane with an unknown yield and a purity of 99%. This patent method obtains 1,2,3-tris(cyanoethoxy)propane with a purity of 99% by distillation under reduced pressure, and the yield is not mentioned. However, in this invention, TGA thermal analysis test is carried out on 1,2,3-tris(cyanoethoxy)propane, and it is found that the sample starts to decompose and lose weight from 206 °C, and the boiling point of 1,2,3-tris(cyanoethoxy)propane under reduced pressure (1 torr) is 250 °C. Thus, it can be seen that distillation under reduced pressure is not a feasible method to obtain high-purity products with high yield. Summary of the Invention

[0012] In order to solve the above technical problems, the present invention provides a purification method of 1,2,3-tris(cyanoethoxy)propane with simple process, which can efficiently remove dinitrile impurities, has high purification efficiency, high product purity, and is suitable for industrial application.

[0013] The object of the present invention is achieved by the following technical solutions:

[0014] A purification method of 1,2,3-tris(cyanoethoxy)propane, specifically comprising the following steps:

[0015] A1. Mix the crude product of 1,2,3-tris(cyanoethoxy)propane, the impurity removal reagent and the organic solvent and react for 0.5 - 12 h to form a reaction solution. The crude product of 1,2,3-tris(cyanoethoxy)propane contains 0.5% - 5% dinitrile impurities, and the impurity removal reagent is selected from at least one of acid anhydride compounds, halogenated sulfonic acids, halogenated phosphoric acids or acyl halide compounds;

[0016] A2. Neutralize the reaction solution with an alkaline solution, then wash to remove salts, and distill to obtain 1,2,3-tris(cyanoethoxy)propane product. The purity of the 1,2,3-tris(cyanoethoxy)propane product is greater than 99.9%, and the dinitrile impurities are less than 0.1%.

[0017] The research of the present invention finds that the dinitrile impurities contain unsubstituted hydroxyl groups. Generally, hydroxyl groups have good reactivity. The dinitrile impurities react with the impurity removal reagent, causing the dinitrile impurities obtained in the reaction to be converted into structures with hydrophilic groups, and through the methods of alkali neutralization and water washing, the dinitrile impurities are finally separated from the organic system in the form of salts. And the impurity removal reagent of the present invention can effectively remove dinitrile impurities without reacting with 1,2,3-tris(cyanoethoxy)propane and without introducing new impurities.

[0018] Furthermore, the impurity removal reagent is selected from at least one of acid anhydrides, halogenated sulfonic acids, halogenated phosphoric acids or acyl halide compounds. Specifically, the acid anhydride is selected from at least one of succinic anhydride, glutaric anhydride, phthalic anhydride, maleic anhydride, itaconic anhydride, sulfuric anhydride or pyrophosphoryl chloride; preferably, the acid anhydride is selected from at least one of succinic anhydride, maleic anhydride or sulfuric anhydride. The halogenated sulfonic acid is selected from at least one of fluorosulfonic acid, chlorosulfonic acid or bromosulfonic acid; preferably, the halogenated sulfonic acid is chlorosulfonic acid. The halogenated phosphoric acid is selected from at least one of monochlorophosphoric acid, dichlorophosphoric acid, monofluorophosphoric acid, difluorophosphoric acid, monobromophosphoric acid or dibromophosphoric acid; preferably, the halogenated phosphoric acid is selected from at least one of monochlorophosphoric acid or dichlorophosphoric acid. The acyl halide compound is selected from at least one of thionyl chloride, thionyl fluoride, phosphorus oxychloride or phosphorus oxybromide; preferably, the acyl halide compound is selected from at least one of thionyl chloride or phosphorus oxychloride.

[0019] The molar amount of the impurity removal reagent of the present invention can effectively convert the dinitrile impurities. Specifically, the molar amount of the impurity removal reagent is 1-10 eq of the dinitrile impurities in the product; preferably, the molar amount of the impurity removal reagent is 1-2 eq of the dinitrile impurities in the product.

[0020] The organic solvent of the present invention can reduce the concentration of reactants in the reaction system, reduce the generation of side reactions, and improve the purification efficiency. Specifically, the organic solvent is selected from at least one of n-hexane, cyclohexane, heptane, dichloromethane, dichloroethane, chloropropane, dichloropropane, chlorobutane, toluene, xylene or chlorobenzene; preferably, the organic solvent is selected from at least one of dichloromethane, dichloroethane or toluene.

[0021] Preferably, the reaction time is 1-3 h. The reaction temperature is 0-50 °C, preferably 10-30 °C.

[0022] The alkali solution is selected from at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide or potassium hydroxide; preferably, the alkali solution is selected from at least one of sodium carbonate or potassium carbonate.

[0023] Specifically, in step A1, when the impurity removing reagent is an acid anhydride, a base-binding agent needs to be added to the reaction system. The base-binding agent is selected from at least one of triethylamine, pyridine, N,N-diisopropylethylamine, 4-dimethylaminopyridine, triethanolamine, tetrabutylammonium bromide, potassium carbonate, ammonium carbonate or sodium carbonate; preferably, the base-binding agent is triethylamine or pyridine.

[0024] In step A2, first, the reaction solution is neutralized with the alkali solution, and the organic phase is obtained by liquid separation; then, the organic phase is washed with deionized water for 1 to 10 times, and the organic phase is separated; the organic solvent is removed by distillation to obtain the 1,2,3-tris(cyanoethoxy)propane product.

[0025] The present invention also provides an application of the above 1,2,3-tris(cyanoethoxy)propane product. The dinitrile impurities in the 1,2,3-tris(cyanoethoxy)propane product are less than 0.1%, and it is used as an additive for lithium-ion battery electrolytes.

[0026] Compared with the prior art, the beneficial effects of the present invention include:

[0027] 1. The present invention can efficiently remove dinitrile impurities, and the 1,2,3-tris(cyanoethoxy)propane product purified by the present invention has high purity and is used as an additive for lithium-ion battery electrolytes;

[0028] 2. The purification method described in the present invention has simple process conditions and is easy to operate, has no influence on the product 1,2,3-tris(cyanoethoxy)propane, and the purification yield is greater than 95%, which is suitable for industrial production. Specific Embodiments

[0029] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternative solutions, improvement solutions and equivalent solutions that may be included within the scope of the claims.

[0030] In the embodiments of the present invention, gas chromatography analysis is used. The analysis instrument is Shimadzu GC-2010PLUS; chromatographic column: SE-30. GC analysis method: detector temperature 330 °C, vaporization chamber temperature 300 °C, column temperature: 80 °C (3 min) 15 °C / min 270 °C (15 min); carrier gas (N 2 ) flow rate 100 mL / min, air flow rate 400 mL / min, hydrogen flow rate 47 mL / min, split ratio 40:1, injection volume 0.6 μL.

[0031] In the embodiments of the present invention, the 1,2,3-tris(cyanoethoxy)propane used is the same batch of crude product prepared by self, which is fully washed with water, dried and desolvated. The crude product is a colorless transparent liquid, the content of 1,2,3-tris(cyanoethoxy)propane is 98.6%, and the content of dinitrile impurities is 1.4%.

[0032] Example 1

[0033] A1. At room temperature, add 100 g of the crude product of 1,2,3-tris(cyanoethoxy)propane, 1.0 g of succinic anhydride, 200 g of dichloromethane, and 0.7 g of triethylamine into a 500 mL three-necked flask, and stir and react at room temperature for 3 hours to obtain a reaction solution.

[0034] A2. Dropwise add a 3% aqueous sodium carbonate solution to the above reaction solution, neutralize to pH = 7.0, separate to obtain an organic phase; then wash the organic phase with 100 g of deionized water, repeat the washing 3 times, separate the organic phase; distill off the organic solvent to obtain 96.6 g of 1,2,3-tris(cyanoethoxy)propane product.

[0035] Calculated, the purification yield of the 1,2,3-tris(cyanoethoxy)propane product is 96.6%; analyzed by GC, the purity of the product is 99.9%, and the content of dinitrile impurities is 0.01%.

[0036] Example 2

[0037] A1. At room temperature, add 100 g of the crude product of 1,2,3-tris(cyanoethoxy)propane, 200 g of dichloromethane, and 1.2 g of chlorosulfonic acid into a 500 mL three-necked flask, and stir and react at room temperature for 1 hour to obtain a reaction solution.

[0038] A2. Dropwise add a 3% aqueous sodium carbonate solution to the above reaction solution, neutralize to pH = 7.0, separate to obtain an organic phase; then wash the organic phase with 100 g of deionized water, repeat the washing 3 times, separate the organic phase; distill off the organic solvent to obtain 95.2 g of 1,2,3-tris(cyanoethoxy)propane product.

[0039] Calculated, the purification yield of the 1,2,3-tris(cyanoethoxy)propane product is 95.2%; analyzed by GC, the purity of the product is 99.9%, and the content of dinitrile impurities is 0.02%.

[0040] Example 3

[0041] The operation of Example 3 is the same as that of Example 2, the only difference is that: the impurity removal reagent is changed to 0.9 g of monochlorophosphoric acid, and other operations remain unchanged, to obtain 95.5 g of 1,2,3-tris(cyanoethoxy)propane product.

[0042] After calculation, the purification yield of the 1,2,3-tris(cyanoethoxy)propane product is 95.5%; by GC analysis, the purity of the product is 99.9%, and the dinitrile impurity is 0.05%.

[0043] Example 4

[0044] The operation of Example 4 is the same as that of Example 2, except that: the impurity removal reagent is changed to 1.0 sulfuryl chloride, and other operations remain unchanged, and 95 g of 1,2,3-tris(cyanoethoxy)propane product is obtained.

[0045] After calculation, the purification yield of the 1,2,3-tris(cyanoethoxy)propane product is 95%; by GC analysis, the purity of the product is 99.9%, and the dinitrile impurity is 0.06%.

[0046] Comparative Example 1

[0047] The operation of Comparative Example 1 is the same as that of Example 1, except that: no impurity removal reagent is added in step A1; no alkali solution is added for neutralization in step A2, and 97.8 g of 1,2,3-tris(cyanoethoxy)propane product is obtained.

[0048] After calculation, the purification yield of the 1,2,3-tris(cyanoethoxy)propane product is 97.8%; by GC analysis, the purity of the product is 98.6%, and the dinitrile impurity is 1.4%.

[0049] Comparative Example 2

[0050] Comparative Example 2 uses vacuum distillation for purification, specifically including: taking 100 g of crude 1,2,3-tris(cyanoethoxy)propane for vacuum distillation, the oil pump pressure is 40 Pa, and the product distillation temperature is 225 - 228 °C, and 78 g of 1,2,3-tris(cyanoethoxy)propane product is obtained.

[0051] After calculation, the distillation yield of the product is 78%; by GC analysis, the purity of the product is 98.2%, and the dinitrile impurity is 1.8%.

[0052] It can be seen from Examples 1 - 4 that the present invention can efficiently remove dinitrile impurities, and the 1,2,3-tris(cyanoethoxy)propane product purified by the present invention has high purity and is used as an additive for lithium-ion battery electrolytes; it can be seen from Comparative Example 1 that conventional purification operations cannot remove dinitrile impurities; it can be seen from Comparative Example 2 that actual vacuum distillation purification is not feasible. Vacuum distillation not only fails to remove dinitrile impurities in the end, but also causes product decomposition, resulting in lower product purity.

Claims

1. A purification method of 1,2,3-tris(cyanoethoxy)propane, characterized in that: The purification method specifically includes the following steps: A1. Mix the crude 1,2,3-tris(cyanoethoxy)propane, the impurity removal reagent and the organic solvent and react for 0.5 - 12 h to form a reaction solution. The crude 1,2,3-tris(cyanoethoxy)propane contains 0.5% - 5% dinitrile impurities, and the impurity removal reagent is selected from at least one of acid anhydride compounds, halogenated sulfonic acids, halogenated phosphoric acids or acyl halide compounds; A2. Neutralize the reaction solution with an alkali solution, then wash to remove salts, and distill to obtain the 1,2,3-tris(cyanoethoxy)propane product. The purity of the 1,2,3-tris(cyanoethoxy)propane product is greater than 99.9%, and the dinitrile impurities are less than 0.1%.

2. The purification method of 1,2,3-tris(cyanoethoxy)propane according to claim 1, characterized in that: The acid anhydride compound is selected from at least one of succinic anhydride, glutaric anhydride, phthalic anhydride, maleic anhydride, itaconic anhydride, sulfuric anhydride or pyrophosphoryl chloride; the halogenated sulfonic acid is selected from at least one of fluorosulfonic acid, chlorosulfonic acid or bromosulfonic acid; the halogenated phosphoric acid is selected from at least one of monochlorophosphoric acid, dichlorophosphoric acid, monofluorophosphoric acid, difluorophosphoric acid, monobromophosphoric acid or dibromophosphoric acid; the acyl halide compound is selected from at least one of thionyl chloride, thionyl fluoride, phosphorus oxychloride or phosphorus oxybromide.

3. The purification method of 1,2,3-tris(cyanoethoxy)propane according to claim 1, characterized in that: The molar amount of the impurity removal reagent is 1 - 10 eq of the dinitrile impurities in the crude 1,2,3-tris(cyanoethoxy)propane.

4. The purification method of 1,2,3-tris(cyanoethoxy)propane according to claim 1, characterized in that: The organic solvent is selected from at least one of n-hexane, cyclohexane, heptane, dichloromethane, dichloroethane, chloropropane, dichloropropane, chlorobutane, toluene, xylene or chlorobenzene.

5. The purification method of 1,2,3-tris(cyanoethoxy)propane according to claim 1, characterized in that: The reaction time is 1 - 3 h, and the reaction temperature is 0 - 50 °C.

6. The purification method of 1,2,3-tris(cyanoethoxy)propane according to claim 1, characterized in that: When the impurity removal reagent is an acid anhydride, a deacidifying agent needs to be added to the reaction system. The deacidifying agent is selected from at least one of triethylamine, pyridine, N,N-diisopropylethylamine, 4-dimethylaminopyridine, triethanolamine, tetrabutylammonium bromide, potassium carbonate, ammonium carbonate or sodium carbonate.

7. The purification method of 1,2,3-tris(cyanoethoxy)propane according to claim 1, characterized in that: The alkali solution is selected from at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide or potassium hydroxide.

8. An application of the 1,2,3-tris(cyanoethoxy)propane product according to claim 1, characterized in that: The dinitrile impurities of the 1,2,3-tris(cyanoethoxy)propane product are less than 0.1%, and it is used as an additive for lithium-ion battery electrolytes.

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