阅读说明：本技术 4,5-二氰基-2-三氟甲基咪唑盐的合成方法 (Synthesis method of 4, 5-dicyano-2-trifluoromethyl imidazole salt ) 是由 时二波 刘磊 印李达 吕鹏程 岳立 朱逸 于 2020-05-19 设计创作，主要内容包括：本发明公开了一种4,5-二氰基-2-三氟甲基咪唑盐的合成方法,包括：先将三苯基膦与碘加入有机溶剂中室温搅拌；然后加入三氟乙酸盐室温搅拌；接着将二氨基顺丁烯二腈加入体系中,先室温搅拌,后回流搅拌,得到含产物的反应液；反应液经纯化后得产品4,5-二氰基-2-三氟甲基咪唑盐。本发明采用一锅法制备,具有反应条件温和、无需苛刻条件,可控性强,后处理简单,易操作,原子经济性好的优点,利于工业化规模生产。(The invention discloses a method for synthesizing 4, 5-dicyano-2-trifluoromethyl imidazole salt, which comprises the following steps: adding triphenylphosphine and iodine into an organic solvent, and stirring at room temperature; then adding trifluoroacetate into the mixture and stirring the mixture at room temperature; adding diaminomaleonitrile into the system, stirring at room temperature, and then refluxing and stirring to obtain a reaction solution containing a product; purifying the reaction liquid to obtain the product 4, 5-dicyano-2-trifluoromethyl imidazole salt. The invention adopts a one-pot method for preparation, has the advantages of mild reaction conditions, no need of harsh conditions, strong controllability, simple post-treatment, easy operation and good atom economy, and is beneficial to industrial mass production.)

A method for synthesizing a 4, 5-dicyano-2-trifluoromethyl imidazole salt, comprising: adding triphenylphosphine and iodine into an organic solvent, and stirring at room temperature; then adding trifluoroacetate into the mixture and stirring the mixture at room temperature; adding diaminomaleonitrile into the system, stirring at room temperature, and then refluxing and stirring to obtain a reaction solution containing a product; purifying the reaction liquid to obtain the product 4, 5-dicyano-2-trifluoromethyl imidazole salt.

2. The method of synthesizing 4, 5-dicyano-2-trifluoromethylimidazole salt according to claim 1, characterized in that: the feeding amount of triphenylphosphine and iodine is 1:1 in molar ratio.

3. The method of synthesizing 4, 5-dicyano-2-trifluoromethylimidazole salt according to claim 1, characterized in that: the molar weight ratio of the fed amounts of the trifluoroacetate, the triphenylphosphine and the iodine is 1:1-1.5: 1-1.5.

4. The method of synthesizing 4, 5-dicyano-2-trifluoromethylimidazole salt according to claim 1, characterized in that: adding triphenylphosphine and iodine into an organic solvent, and stirring for 10-60 minutes; after the trifluoroacetic acid salt is added, the stirring time is 40-120 minutes.

5. The method of synthesizing 4, 5-dicyano-2-trifluoromethylimidazole salt according to claim 1, characterized in that: the feeding molar weight of the diaminomaleonitrile and the trifluoroacetate is 1: 1.

6. The method of synthesizing 4, 5-dicyano-2-trifluoromethylimidazole salt according to claim 1, characterized in that: after the diaminomaleonitrile is added, the stirring time at room temperature is 1 to 5 hours, and the reflux stirring time is 2 to 8 hours.

7. The method of synthesizing 4, 5-dicyano-2-trifluoromethylimidazole salt according to claim 1, characterized in that: the trifluoroacetate is at least one of lithium salt, sodium salt, potassium salt and magnesium salt.

8. The method of synthesizing 4, 5-dicyano-2-trifluoromethylimidazole salt according to claim 1, characterized in that: the purification step comprises: adding water for separating liquid, decoloring by using activated carbon, filtering, concentrating, recrystallizing by using a mixed solution of acetonitrile and toluene in a mass ratio of 1:1, and drying to obtain a pure product.

9. The method of synthesizing 4, 5-dicyano-2-trifluoromethylimidazole salt according to claim 8, characterized in that: the drying temperature is 100-140 deg.C and the drying time is 2-5 hr.

10. The method for the synthesis of 4, 5-dicyano-2-trifluoromethylimidazole salt according to claims 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9, characterized in that: the organic solvent is at least one of 1, 4-dioxane, glycol dimethyl ether and acetonitrile.

Technical Field

The invention relates to the technical field of organic synthetic chemistry, in particular to a synthetic method of 4, 5-dicyano-2-trifluoromethyl imidazole salt.

Background

In the last two decades, secondary lithium ion batteries have been widely used in the fields of portable electronic devices, energy storage, electric vehicles, and the like. Lithium salts in the electrolyte of commercial secondary lithium ion batteries are the main source of lithium and are important for the full and stable performance of the batteries. At present, lithium hexafluorophosphate is dominant in commercial electrolyte lithium salt, but due to the characteristics of easiness in hydrolysis and high-temperature easiness in decomposition, the lithium ion battery has certain hidden danger in the aspect of safe use, and the wide application of lithium hexafluorophosphate is limited to a certain extent. Although a number of other types of lithium salts have been investigated in an attempt to replace lithium hexafluorophosphate, lithium hexafluorophosphate has, to date, dominated commercial lithium ion batteries. Therefore, the search for lithium salts having stable structures and excellent performance is extremely important for the future development of secondary lithium ion batteries.

4, 5-dicyano-2-trifluoromethyl imidazole lithium is expected to replace lithium hexafluorophosphate to be used as main salt of secondary lithium ion battery electrolyte, has good stability to water, high electrochemical oxidation potential and high corrosion potential of an aluminum foil current collector, and has high lithium ion migration number, and the thermal decomposition temperature can reach over 250 ℃. Therefore, the 4, 5-dicyano-2-trifluoromethyl imidazole lithium is expected to realize industrial production and application when the secondary lithium ion battery is developed on a large scale in the future.

At present, the synthesis route of 4, 5-dicyano-2-trifluoromethylimidazole lithium is known to be mostly a two-step or three-step reaction, firstly preparing 4, 5-dicyano-2-trifluoromethylimidazole, and then reacting 4, 5-dicyano-2-trifluoromethylimidazole with lithium carbonate to prepare 4, 5-dicyano-2-trifluoromethylimidazole lithium. The specific synthetic route comprises: firstly, the Diaminomaleonitrile (DAMN) and trifluoroacetic anhydride (TFAA) are used for preparing the compound by a two-step reaction, and the method has the defects that: the TFAA has low boiling point and is volatile, needs to be dripped at low temperature, is decomposed when meeting water to generate toxic and harmful gas, and is not beneficial to large-scale industrial production. Secondly, the preparation is carried out by two-step reaction by using DAMN, trifluoroacetic acid (TFA) and phosphorus pentoxide, and the method has the defects that: the TFA is strong acid and has strong corrosivity; phosphorus pentoxide reacts very readily with water and can produce toxic metaphosphoric acid by reaction with cold water. The method has strict requirements on equipment and is not beneficial to industrial production. And thirdly, performing aminolysis reaction on the DAMN and trifluoroacetate, performing intramolecular dehydration, and then reacting with lithium carbonate, wherein three steps of conversion are required. The disadvantages of this method are: the lower trifluoroacetate has low boiling point, is not beneficial to metering and is inflammable, and the higher trifluoroacetate has low utilization rate of reaction atoms and poor economical efficiency.

Disclosure of Invention

In order to solve the technical problems, the invention provides a synthesis method of 4, 5-dicyano-2-trifluoromethyl imidazole salt, which has the advantages of mild reaction conditions, simple reaction process and post-treatment, easy operation and good atom economy.

In order to solve the technical problems, the specific technical scheme of the invention is as follows: the synthesis process of 4, 5-dicyano-2-trifluoromethyl imidazole salt includes the following steps: adding triphenylphosphine and iodine into an organic solvent, and stirring at room temperature; then adding trifluoroacetate into the mixture and stirring the mixture at room temperature; adding diaminomaleonitrile into the system, stirring at room temperature, and then refluxing and stirring to obtain a reaction solution containing a product; purifying the reaction liquid to obtain the product 4, 5-dicyano-2-trifluoromethyl imidazole salt.

Further, in the method for synthesizing the 4, 5-dicyano-2-trifluoromethyl imidazole salt, the feeding amount of triphenylphosphine and iodine is 1:1 in a molar ratio.

Further, in the synthesis method of the 4, 5-dicyano-2-trifluoromethyl imidazole salt, the molar weight ratio of the fed amounts of the trifluoroacetate, the triphenylphosphine and the iodine is 1:1-1.5: 1-1.5.

Further, in the synthesis method of the 4, 5-dicyano-2-trifluoromethyl imidazole salt, after triphenylphosphine and iodine are added into an organic solvent, stirring is carried out for 10-60 minutes; after the trifluoroacetic acid salt is added, the stirring time is 40-120 minutes.

Further, in the synthesis method of the 4, 5-dicyano-2-trifluoromethyl imidazole salt, the feeding molar amount of the diaminomaleonitrile and the trifluoroacetate is 1: 1.

Further, in the synthesis method of the 4, 5-dicyano-2-trifluoromethyl imidazole salt, after the diaminomaleonitrile is added, the stirring time at room temperature is 1 to 5 hours, and the reflux stirring time is 2 to 8 hours.

Further, in the synthesis method of the 4, 5-dicyano-2-trifluoromethyl imidazole salt, the trifluoroacetate is at least one of lithium salt, sodium salt, potassium salt and magnesium salt.

Further, the synthesis method of the 4, 5-dicyano-2-trifluoromethyl imidazole salt comprises the following purification steps: adding water for separating liquid, decoloring by using activated carbon, filtering, concentrating, recrystallizing by using a mixed solution of acetonitrile and toluene in a mass ratio of 1:1, and drying to obtain a pure product.

Further, the synthesis method of the 4, 5-dicyano-2-trifluoromethyl imidazole salt is characterized in that the drying temperature is 100-140 ℃ and the drying time is 2-5 hours during purification.

Further, in the method for synthesizing the 4, 5-dicyano-2-trifluoromethyl imidazole salt, the organic solvent is at least one of 1, 4-dioxane, ethylene glycol dimethyl ether and acetonitrile.

The invention has the advantages that: firstly, trifluoroacetic acid salt is adopted, volatile trifluoroacetic anhydride and methyl trifluoroacetate with low boiling points are avoided, the safety of reaction operation is greatly improved, low-boiling-point organic matters are effectively prevented from escaping from a system, and a low-temperature dropping system is not needed. And the trifluoroacetic acid salt is adopted, so that the atom utilization rate is greatly improved and the production cost can be effectively reduced compared with trifluoroacetic anhydride and trifluoroacetic acid ester. And thirdly, the whole reaction process adopts a one-pot method, the operation is relatively simple, the method is suitable for large-scale industrial production, and the equipment investment is low.

Drawings

FIG. 1 shows the NMR spectrum of the product obtained in example one.

FIG. 2 is a NMR carbon spectrum of the product obtained in the first example.

Detailed Description

The method for synthesizing the 4, 5-dicyano-2-trifluoromethylimidazole salt according to the present invention will be described in further detail with reference to preferred examples.

The first embodiment.

By stirring with beltsA 1L three-neck flask with a stirrer, a thermometer and a reflux condenser, wherein Ph is firstly added in the atmosphere of a glove box₃P (0.1 mol, 26.2 g) and I₂(0.1 mol, 25.4 g) was added to 1, 4-dioxane (200 mL) and stirred at room temperature for 30 minutes; then adding lithium trifluoroacetate (0.1 mol, 12.0 g) into the reaction system, and continuing stirring at room temperature for 60 minutes; and then adding diaminomaleonitrile (0.1 mol, 10.8 g) into the reaction system, stirring for 2 hours to generate intermediate amide, gradually heating to a reflux state, stirring for 4 hours, and directly obtaining a mixed solution containing 4, 5-dicyano-2-trifluoromethyl imidazole lithium after amide dehydration.

Transferring the mixed solution into a 1L flask, adding 200 mL of deionized water, adding 8 g of activated carbon for decolorization, filtering, separating the obtained filtrate, collecting a water layer, concentrating to dryness, adding 200 g of mixed solvent of acetonitrile and toluene in a mass ratio of 1:1, filtering, recrystallizing to obtain a crystal product, and drying at 120 ℃ for 3 hours to obtain 17.3 g of white solid lithium salt, wherein the yield is 90% and the purity is 99.95%. Product adoption¹³C NMR (FIG. 1) and¹⁹f NMR (FIG. 2) detected no significant impurity.

Example two.

Ph was measured in a glove box atmosphere using a 1L three-necked flask equipped with a stirrer, a thermometer and a reflux condenser₃P (0.1 mol, 26.2 g) and I₂(0.1 mol, 25.4 g) were added to acetonitrile (200 mL) and stirred at room temperature for 20 minutes; then adding potassium trifluoroacetate (0.1 mol, 15.2 g) into the reaction system, and continuing stirring at room temperature for 40 minutes; and then adding diaminomaleonitrile (0.1 mol, 10.8 g) into the reaction system, stirring for 4 hours to generate intermediate amide, gradually heating to a reflux state, stirring for 6 hours, and directly obtaining a mixed solution containing 4, 5-dicyano-2-trifluoromethyl imidazole potassium after amide dehydration.

Transferring the mixed solution into a 1L flask, adding 200 mL of deionized water, adding 8 g of activated carbon for decolorization, filtering, separating the obtained filtrate, collecting a water layer, concentrating to dryness, adding 200 g of mixed solvent of acetonitrile and toluene in a mass ratio of 1:1, filtering, recrystallizing to obtain a crystal product, and drying at 120 ℃ for 3 hours to obtain 18.4 g of white solid potassium salt, wherein the yield is 82% and the purity is 99.97%.

Example three.

Ph was measured in a glove box atmosphere using a 1L three-necked flask equipped with a stirrer, a thermometer and a reflux condenser₃P (0.12 mol, 31.4 g) and I₂(0.12 mol, 30.5 g) were added to ethylene glycol dimethyl ether (200 mL) respectively, and stirred at room temperature for 40 minutes; then adding sodium trifluoroacetate (0.1 mol, 13.6 g) into the reaction system, and continuing stirring for 80 minutes at room temperature; and then adding diaminomaleonitrile (0.1 mol, 10.8 g) into the reaction system, stirring for 2 hours to generate intermediate amide, gradually heating to a reflux state, stirring for 3 hours, and directly obtaining a mixed solution containing 4, 5-dicyano-2-trifluoromethyl imidazole sodium after the amide is dehydrated.

Transferring the mixed solution into a 1L flask, adding 200 mL of deionized water, adding 12 g of activated carbon for decolorization, filtering, separating the obtained filtrate, collecting a water layer, concentrating to dryness, adding 200 g of mixed solvent of acetonitrile and toluene in a mass ratio of 1:1, filtering, recrystallizing to obtain a crystal product, and drying at 100 ℃ for 5 hours to obtain 17.0 g of white solid sodium salt, wherein the yield is 80% and the purity is 99.93%.

The invention abandons the traditional synthesis method, skillfully designs a synthesis route, takes diaminomaleonitrile and trifluoroacetate as initial raw materials, produces amide under the action of triphenylphosphine and iodine, and then directly prepares the 4, 5-dicyano-2-trifluoromethyl imidazole salt through intramolecular dehydration.

From the above examples: the synthesis method has mild reaction conditions, no need of harsh conditions, strong controllability, simple post-treatment, and high-purity products can be obtained at high yield by only decoloring and recrystallizing.