A hexafluorophosphoric acid complex and its synthesis method and application

Abstract

The invention discloses a method for synthesizing a hexafluorophosphate complex, which comprises reacting a Lewis base with any one of hydrogen fluoride and phosphorus pentafluoride, and then reacting with the other of hydrogen fluoride and phosphorus pentafluoride, wherein the Lewis base contains one or more of nitrogen atoms, oxygen atoms and sulfur atoms. The synthesis method of the invention can synthesize a high-purity hexafluorophosphate complex, and the synthesized hexafluorophosphate complex can be used as a catalyst in the field of organic synthesis and biomedicine, and can also be used as a raw material for synthesizing hexafluorophosphate.

Description

Technical Field

[0001] The invention specifically relates to a hexafluorophosphate complex and a synthesis method and application thereof. Background Art

[0002] Hexafluorophosphoric acid is a commonly used inorganic acid with good applications in catalysis and biology. Hexafluorophosphoric acid is also an important raw material for synthesizing hexafluorophosphate, which is the electrolyte material with the best comprehensive performance and the most wide application in current secondary batteries, and its demand is huge.

[0003] Hexafluorophosphoric acid is unstable and easily decomposes into phosphorus pentafluoride gas and hydrogen fluoride gas. Therefore, hexafluorophosphoric acid usually exists in the form of an aqueous solution. The hexafluorophosphoric acid aqueous solution maintains the structure of hexafluorophosphoric acid to a certain extent, but hexafluorophosphoric acid will hydrolyze in water to generate various impurities such as monofluorophosphoric acid, difluorophosphoric acid and phosphoric acid. Therefore, even if hexafluorophosphoric acid is used as a raw material in the form of an aqueous solution to prepare downstream products (such as hexafluorophosphate), the impurity content in the downstream products is still high, and the downstream products still require complex separation and purification steps, thereby increasing the production cost of the downstream products. Summary of the invention

[0004] The object of the present invention is to provide a hexafluorophosphate complex and a synthesis method thereof, wherein the synthesis method can prepare a high-purity hexafluorophosphate complex.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The invention provides a method for synthesizing a hexafluorophosphate complex, which comprises reacting a Lewis base with any one of hydrogen fluoride and phosphorus pentafluoride, and then reacting with the other of hydrogen fluoride and phosphorus pentafluoride, wherein the Lewis base contains one or more of a nitrogen atom, an oxygen atom and a sulfur atom.

[0007] The invention uses a Lewis base containing a lone pair of electrons to complex with phosphorus pentafluoride, and then forms a hexafluorophosphoric acid complex with hydrogen fluoride. The complex has high purity and can exist stably.

[0008] Preferably, the Lewis base is selected from one or more of amine compounds, ether compounds, sulfur compounds, and carboxylate compounds, wherein the amine compounds are linear amines and / or cyclic amines, and the linear amines include one or more of methylamine, ethylamine, ethylenediamine, monoethanolamine, diethanolamine, triethylamine, isopropylamine, and diisopropylamine; the cyclic amines include one or more of pyridine and its derivatives, pyrimidine and its derivatives, pyrrolidine, formylpiperidine, aniline and its derivatives, piperazine and its derivatives, and triethylenediamine; the ether compounds are linear ethers and / or cyclic ethers, and the linear ethers include one or more of diethyl ether, methyl ethyl ether, dipropyl ether, ethyl propyl ether, phenyl methyl ether, phenyl ethyl ether, ethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and derivatives of the above linear ethers; the cyclic ethers include tetrahydrofuran and its derivatives, 1 ,4-dioxane and one or more of its derivatives; the sulfur compound is a sulfur-containing straight-chain compound and / or a sulfur-containing cyclic compound, and the sulfur-containing straight-chain compound includes diethyl sulfide, methyl ethyl sulfide, dipropyl sulfide, ethyl propyl sulfide, diphenyl sulfide, phenyl methyl sulfide, ethylene glycol dimethyl sulfide and one or more of the derivatives of the above-mentioned sulfur-containing straight-chain compounds; the sulfur-containing cyclic compound includes one or more of thiophene and its derivatives; the carboxylate compound is a straight-chain carboxylate compound and / or a cyclic carboxylate compound, and the straight-chain carboxylate compound includes ethyl acetate, propyl acetate, phenyl acetate and the derivatives of the above-mentioned straight-chain carboxylate compounds; the cyclic carboxylate compound includes γ-butyrolactone, β-propiolactone, α-furan ester and one or more of the derivatives of the above-mentioned cyclic carboxylate compounds.

[0009] Preferably, the temperature of the system is controlled to be -50~10°C.

[0010] According to some preferred embodiments, after the Lewis base reacts with the hydrogen fluoride and then reacts with the phosphorus pentafluoride, the temperature of the system is controlled to be -30~10°C.

[0011] According to some preferred embodiments, after the Lewis base reacts with the phosphorus pentafluoride and then reacts with the hydrogen fluoride, the temperature of the system is controlled to be -30~10°C.

[0012] Preferably, the molar amount of the hydrogen fluoride fed is greater than the molar amount of the phosphorus pentafluoride fed.

[0013] Further preferably, the molar ratio of the hydrogen fluoride to the Lewis base is (1-10):1; and / or the molar ratio of the phosphorus pentafluoride to the Lewis base is 1:(1-5).

[0014] More preferably, the molar ratio of the hydrogen fluoride to the Lewis base is (2-5):1.

[0015] More preferably, the molar ratio of the phosphorus pentafluoride to the Lewis base is 1:(3-5).

[0016] Preferably, after the reaction is completed, the temperature of the reaction system is controlled to be -30 to -10°C to allow the hexafluorophosphate complex to crystallize, and the precipitated hexafluorophosphate complex is washed and dried.

[0017] Further preferably, the hexafluorophosphate complex is washed with an organic solvent, and the organic solvent includes one or more of cyclohexane, chloroform, dichloromethane, and carbon tetrachloride.

[0018] Further preferably, the drying method is vacuum drying, and the drying temperature is controlled to be 10-50°C.

[0019] Preferably, the hydrogen fluoride is fed in a gaseous state or a liquid state. When the hydrogen fluoride is fed in a liquid state, the hydrogen fluoride is added to the system in a dropwise manner to prevent local overheating and ensure the safety of the process.

[0020] The second aspect of the present invention provides a hexafluorophosphate complex synthesized by the above-mentioned synthesis method.

[0021] The third aspect of the present invention provides an application of a hexafluorophosphate complex synthesized by the synthesis method as described above in the preparation of hexafluorophosphate.

[0022] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0023] The synthesis method of the invention can synthesize a high-purity hexafluorophosphate complex, and the hexafluorophosphate can stably exist in the hexafluorophosphate complex, so that the hexafluorophosphate complex can be used in catalysis and biological fields, and can also be used as a raw material to synthesize hexafluorophosphate. DETAILED DESCRIPTION

[0024] The inventors unexpectedly discovered that by reacting a Lewis base with either hydrogen fluoride or phosphorus pentafluoride and then reacting with the other of hydrogen fluoride and phosphorus pentafluoride, a high-purity hexafluorophosphoric acid complex can be synthesized, thereby allowing hexafluorophosphoric acid to exist stably without the need for an aqueous solution. This solution is further discussed below.

[0025] According to some specific and preferred embodiments, a method for synthesizing a hexafluorophosphate complex comprises the following steps:

[0026] s1 Pass phosphorus pentafluoride into Lewis base for reaction, and control the reaction temperature to -50~10℃;

[0027] s2: introduce hydrogen fluoride into the system of s1 and control the temperature of the system to -50~10℃;

[0028] S3: Control the temperature of the S2 system to -30~-10℃ to allow the hexafluorophosphate complex to crystallize and precipitate;

[0029] s4 After filtering the system of s3, washing with a solvent to remove excess reactants, vacuuming and drying to obtain high-purity crystals.

[0030] The above reaction equation is as follows:

[0031] PF5+ A (Lewis base) → A•PF5

[0032] A•PF5+ HF→AH + PF6 -

[0033] According to some other specific and preferred embodiments, a method for synthesizing a hexafluorophosphate complex comprises the following steps:

[0034] S1 Add hydrogen fluoride to Lewis base for reaction, and control the reaction temperature to -50~10℃;

[0035] S2 introduces phosphorus pentafluoride into the system of S1 and controls the temperature of the system to -50~10℃;

[0036] S3 controls the temperature of the S2 system to -30~-10°C to allow the hexafluorophosphate complex to crystallize and precipitate;

[0037] S4 After filtering the system of S3, washing with a solvent to remove excess reactants, vacuuming and drying to obtain high-purity crystals.

[0038] The above reaction equation is as follows:

[0039] HF + A (Lewis base) → AH + F -

[0040] AH + F - + PH5→AH + PF6 -

[0041] The solution of the present invention has at least the following advantages:

[0042] (1) The present invention synthesizes a hexafluorophosphate complex, and the hexafluorophosphate can be stably present in the hexafluorophosphate complex, so that the hexafluorophosphate can be stably present without being in the form of an aqueous solution, thereby avoiding the hydrolysis of the hexafluorophosphate in water and improving the purity of the hexafluorophosphate.

[0043] (2) The hexafluorophosphoric acid complex synthesized by the present invention has high purity. When used as a raw material, it can reduce the difficulty of separation and purification of downstream products, reduce the burden and cost of separation and purification for enterprises, and to a certain extent expand the application field of hexafluorophosphoric acid.

[0044] (3) The synthesis method of the present invention is simple and easy to operate.

[0045] The present invention is further described below in conjunction with the examples. However, the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to the different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in each embodiment of the present invention can be combined with each other as long as they do not conflict with each other.

[0046] Unless otherwise specified, the following examples and comparative examples were carried out under normal pressure, and the drying temperature was controlled to be 10-50°C.

[0047] Example 1

[0048] At -10°C, 100 g (5 mol) of liquid hydrogen fluoride was added dropwise to 192 g (1.87 mol) of diisopropylamine, and the dropping speed was controlled while stirring was maintained to allow the reaction to proceed fully.

[0049] Take 40 ml of the obtained solution, keep the temperature constant, and introduce 0.1 mol of phosphorus pentafluoride gas under stirring. After the ventilation is completed, keep stirring for 30 minutes, cool the system to -20 ° C, and white needle-shaped crystals will appear. After filtering the obtained crystals, wash them with chloroform 2 to 3 times, and vacuum dry them to obtain the product. The mass yield of the product is 86.9% (calculated as phosphorus pentafluoride) and the purity is 98.5% (calculated as C6H 15 NHPF6).

[0050] The product obtained in this example needs to be stored in a dry environment (water content less than 20ppm). For example, at room temperature of 25°C, 25g of the above product is placed in a vacuum desiccator and placed for 7 days. The mass is 25g and the purity is 98.5% (based on C6H 15 After 30 days of storage, the mass was 24.98 g and the purity was 98.5% (based on C6H 15 NHPF6).

[0051] Example 2

[0052] At -20°C, 100 g (5 mol) of liquid hydrogen fluoride was added dropwise to 148 g (1.87 mol) of dehydrated pyridine, and the dropping speed was controlled while stirring was maintained to allow the reaction to proceed fully.

[0053] Take 40 ml of the obtained solution, keep the temperature constant, and pass 0.1 mol of phosphorus pentafluoride gas. After the ventilation is completed, the solution turns light yellow. Continue to keep the system temperature at -20°C, and dendritic white crystals appear. The obtained crystals are filtered, washed with chloroform 2 to 3 times, and vacuum dried to obtain the product. The mass yield of the product is 96.0% (calculated as phosphorus pentafluoride) and the purity is 98.5% (calculated as C5H5NHPF6).

[0054] Example 3

[0055] At -20°C, 100 g (5 mol) of liquid hydrogen fluoride was added dropwise to 276.8 g (1.87 mol) of 2-trifluoromethylpyridine, and the dropping speed was controlled while stirring was maintained to allow the reaction to proceed fully.

[0056] Take 40 ml of the obtained solution, keep the temperature constant, and pass 0.1 mol of phosphorus pentafluoride gas. After the ventilation is completed, the solution turns light yellow. Continue to keep the system temperature at -20°C, and dendritic white crystals appear. The obtained crystals are filtered, washed with chloroform 2 to 3 times, and vacuum dried to obtain the product. The mass yield of the product is 71.7% (calculated as phosphorus pentafluoride) and the purity is 96.2% (calculated as CF3C5H5NHPF6).

[0057] Example 4

[0058] The temperature of the reactor was controlled at 0-5°C, and a predetermined amount of phosphorus pentafluoride gas was introduced into 138.5 g of dehydrated diethyl ether to form a solution in a ratio of 1:4 (molar ratio). After the aeration was completed, stirring was maintained for 30 minutes to allow for sufficient reaction.

[0059] Take 40 ml of the obtained solution, keep the temperature constant, heat 2.4 mol of liquid hydrogen fluoride and pass it into the above solution in the form of gas. After the ventilation is completed, cool to -20°C, needle-shaped white crystals appear, filter the obtained crystals, wash them with chloroform 2 to 3 times, and vacuum dry to obtain the product. The mass yield of the product is 82.5% (calculated as phosphorus pentafluoride) and the purity is 98.2% (calculated as (C2H5)2OHPF6).

[0060] Example 5

[0061] The reactor temperature was controlled at -30°C, and a predetermined amount of phosphorus pentafluoride was introduced into 134.6 g of dehydrated tetrahydrofuran to form a solution at a ratio of 1:4 (molar ratio). After the aeration was completed, stirring was maintained for 30 minutes to allow for sufficient reaction.

[0062] Take 40 ml of the obtained solution, keep the temperature constant, heat 2.4 mol of liquid hydrogen fluoride and pass it into the above solution in the form of gas. After the ventilation is completed, the system temperature is controlled at -20°C, and needle-shaped white crystals appear. The obtained crystals are filtered and washed with chloroform 2 to 3 times, and vacuum dried to obtain the product. The mass yield of the product is 78.0% (calculated as phosphorus pentafluoride) and the purity is 97.5% (calculated as C4H8OHPF6).

[0063] Example 6

[0064] The reactor temperature was controlled at -10°C, and 100 g (5 mol) of liquid hydrogen fluoride was added dropwise to the dehydrated diethyl sulfide under stirring. The mass of diethyl sulfide was 169 g (1.87 mol). After the hydrogen fluoride was added dropwise, stirring was maintained for 30 minutes to allow it to react fully.

[0065] Take 40 ml of the obtained solution, keep the temperature unchanged, and pass 63.0 g (0.5 mol) of phosphorus pentafluoride gas. After the ventilation is completed, cool to -20°C, and needle-shaped white crystals will appear. The obtained crystals are filtered and washed with chloroform 2 to 3 times, and vacuum dried to obtain the product. The mass yield of the product is 75.0% (calculated as phosphorus pentafluoride), and the purity is 92.5% (calculated as (C2H5)2SHPF6).

[0066] Example 7

[0067] The reactor temperature was controlled at -10°C, and 100 g (5 mol) of liquid hydrogen fluoride was added dropwise to thiophene under stirring, with 157 g (1.87 mol) of thiophene. After the addition was completed, the mixture was stirred for 30 minutes to allow for a full reaction.

[0068] Take 40 ml of the above solution, keep the temperature unchanged, and pass 63.0 g (0.5 mol) of phosphorus pentafluoride gas. After the ventilation is completed, cool to -20°C, and needle-shaped white crystals appear. The obtained crystals are filtered and washed with chloroform 2 to 3 times, and vacuum dried to obtain the product. After calculation, the mass yield of the product is 80.0% (calculated as phosphorus pentafluoride), and the purity is 94.5% (calculated as C4H4SHPF6).

[0069] Example 8

[0070] The reactor temperature was controlled at -10°C, and 58.9 g of phosphorus pentafluoride was introduced into 164.8 g of ethyl acetate under stirring conditions to form a solution in a ratio of 1:4 (molar ratio). After the ventilation was completed, stirring was maintained for 30 minutes to allow the solution to react fully.

[0071] Take 40 ml of the obtained solution, keep the temperature unchanged, heat 2.4 mol of liquid hydrogen fluoride and pass it into the above solution in the form of gas. After ventilation, cool to -20°C, needle-shaped white crystals appear, filter the obtained crystals, wash them with chloroform 2 to 3 times, and vacuum dry to obtain the product. After calculation, the mass yield of the product is 78.0% (calculated as phosphorus pentafluoride), and the purity is 95.5% (calculated as CH3COOC2H5HPF6).

[0072] Example 9

[0073] The reactor temperature was controlled at 10°C, and 58.9 g of phosphorus pentafluoride gas was introduced into 161 g of γ-butyrolactone under stirring conditions to form a solution at a ratio of 1:4 (molar ratio). After the aeration was completed, stirring was maintained for 30 minutes to allow for sufficient reaction.

[0074] Take 40 ml of the solution obtained above, keep the temperature constant, heat 2.4 mol of liquid hydrogen fluoride and pass it into the solution in the form of gas. After the ventilation is completed, cool to -20°C, and needle-shaped white crystals appear. The obtained crystals are filtered and washed with cyclohexane 2 to 3 times, and vacuum dried to obtain the product. The product mass yield is calculated to be 72.2% (calculated as phosphorus pentafluoride) and the purity is 95%.

[0075] C4H6O2HPF6).

[0076] Example 10

[0077] At -20°C, 112.6 g (0.5 mol) of the product obtained in Example 1 was dissolved in 50 ml of tetrahydrofuran with 80 g (2 mol) of sodium hydroxide. After sufficient stirring for reaction, the temperature was lowered to -50°C and allowed to stand for 2 h. After filtration, the solid was taken out, washed three times with 50 ml of dichloromethane, and dried under vacuum at 60°C to obtain 97.4 g of sodium hexafluorophosphate with a yield of 86.5% (based on the mass of the product obtained in Example 1). The acidity was analyzed to be 45 ppm (equivalent to HF).

[0078] The above detailed description of the present invention is intended to enable persons familiar with the art to understand the contents of the present invention and implement them. It does not limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for synthesizing a hexafluorophosphate complex, characterized in that: After reacting a Lewis base with either hydrogen fluoride or phosphorus pentafluoride at -50 to 10°C, the Lewis base is reacted with the other of hydrogen fluoride and phosphorus pentafluoride at -50 to 10°C. The Lewis base is selected from one or more of diisopropylamine, pyridine, 2-trifluoromethylpyridine, diethyl ether, tetrahydrofuran, diethyl sulfide, thiophene, ethyl acetate, and γ-butyrolactone. The molar ratio of the hydrogen fluoride to the Lewis base is (1-10): 1, The feeding molar ratio of the phosphorus pentafluoride to the Lewis base is 1:(1-5).

2. The method for synthesizing the hexafluorophosphate complex according to claim 1, characterized in that: The molar ratio of the hydrogen fluoride to the Lewis base is (2-5):1; and / or the molar ratio of the phosphorus pentafluoride to the Lewis base is 1:(3-5).

3. The method for synthesizing the hexafluorophosphate complex according to claim 1, characterized in that: After the reaction is completed, the temperature of the reaction system is controlled to be -30 to -10°C to allow the hexafluorophosphate complex to crystallize, and the precipitated hexafluorophosphate complex is washed and dried.

4. The method for synthesizing the hexafluorophosphate complex according to claim 3, characterized in that: The hexafluorophosphate complex is washed with an organic solvent, wherein the organic solvent includes one or more of cyclohexane, chloroform, dichloromethane and carbon tetrachloride.

5. The method for synthesizing the hexafluorophosphate complex according to claim 1, characterized in that: The hydrogen fluoride is fed in a gaseous state or a liquid state. When the hydrogen fluoride is fed in a liquid state, the hydrogen fluoride is added to the system in a dropwise manner; When the Lewis base reacts with the hydrogen fluoride and then reacts with the phosphorus pentafluoride, the hydrogen fluoride is fed in a liquid state; when the Lewis base reacts with the phosphorus pentafluoride and then reacts with the hydrogen fluoride, the hydrogen fluoride is fed in a gaseous state; and / or the hexafluorophosphate complex is solid.