JP6228862B2 - Process for producing ionic compounds - Google Patents

Description

  The present invention relates to a method for producing an ionic compound.

  The ionic compound is a unique medium having characteristics that are not found in conventional water and organic solvents such as non-volatility, nonflammability, high ionic conductivity, and a wide potential window because of its composition. In particular, since ionic compounds that can be handled in air have been reported, development in a wide variety of fields is highly expected. Particularly noteworthy properties of ionic compounds are non-volatility and a low melting point. These are desirable from the viewpoint of green chemistry such as reduction of environmental burden and prevention of exposure to workers, but at the same time, it is also a cause of making it very difficult to prepare high purity ionic compounds. In fact, even for ionic compounds with the same compound name, different physical property values are often reported depending on the literature. It has been pointed out that such a difference is caused by the purity of the ionic compound used in each report, and establishment of a highly versatile ionic compound synthesis method and purification method has been a long-standing concern. In addition, the cost of the ionic compound itself is an important factor for the engineering application of the ionic compound, but this is also very disadvantageous in the synthesis methods used so far. In order to overcome this situation and expand the range of applications of ionic compounds as new functional materials, it was urgent to establish an innovative synthetic route.

  Conventionally, most ionic compounds have been synthesized by the following two-step synthesis method (hereinafter also referred to as “conventional method”).

(First stage (ionic compound precursor synthesis stage))
Cationic halide salts (ionic compound precursors) that can form ionic compounds are synthesized by nucleophilic substitution reactions between various tertiary amines and alkyl halides.

(Second stage (anion exchange reaction))
The ionic compound is synthesized by an anion exchange reaction between the halide ion of the ionic compound precursor and the anion species that can form the ionic compound.

  Examples of synthesizing ionic compounds by conventional methods include reported examples such as Non-Patent Documents 1 to 3 and Patent Document 1.

JP 2007-518772 A

Organic Synthesis, vol. 82, p. 166-169 (2005). Asian Journal of Chemistry, vol. 22, p. 911-920 (2010). Journal of Chemical Society, Chemical Communications, p. 965-967 (1992).

For example, in the conventional method, 1-ethyl-3-methylimidazolium tetrafluoroborate (hereinafter, also referred to as “EMIBF ₄ ”), which is an ionic compound, was synthesized as follows.

In the conventional method, first, an ionic compound precursor 1-ethyl-3-methylimidazolium bromide (hereinafter also referred to as “EMIBr”) is synthesized in the first step ([Chemical Formula 1]), and then the second step. The target ionic compound (EMIBF ₄ ) was synthesized by performing anion exchange reaction using EMIBr and NaBF ₄ as raw materials in the stage ([Chemical Formula 2]).

Although the conventional method for synthesizing the ionic compound including the method for synthesizing the EMIBF ₄ has already been established, the present inventors have intensively studied, and as a result, newly found to have the following problems. .

For example, in the method of synthesizing EMIBF ₄ , it has been found that it is very difficult to completely exchange Br ⁻ with BF ₄ ⁻ because the anion exchange reaction performed in the second stage has a reversible equilibrium. Further, an inorganic salt such as NaBr with EMIBF ₄ in the conventional method is by-produced as an impurity, because many of the ionic compounds containing EMIBF ₄ is water soluble, it is difficult to remove only inorganic salts by washing with water It turned out to be. Furthermore, since the ionic compound is non-volatile as described above, it has been found that purification by distillation is difficult.

Non-Patent Document 1 reports a synthesis example of 1-butyl-3-methylimidazolium tetrafluoroborate (hereinafter also referred to as “BMIBF ₄ ”) by a conventional method. However, it was found that the synthesized BMIBF ₄ contains many chloride ions derived from inorganic salts as impurities (636 ppm (= 0.405 mol%)), and there is room for further improvement in terms of purity.

In Non-Patent Document 2, a synthesis example of EMIBF ₄ is reported by a conventional method. In this synthesis example, attention is paid to the fact that sodium halide as a by-product is insoluble in acetone, and the use of acetone as a reaction solvent promotes the progress of the anion exchange reaction. However, the progress of the anion exchange reaction is extremely slow, and it takes 7 days to complete the synthesis. For this reason, it has been found that there is room for further improvement in terms of production efficiency.

In Non-Patent Document 3, a synthesis example of EMIBF ₄ is reported by the conventional method as described above. In this synthesis example, the use of silver (I) tetrafluoroborate promotes the progress of the anion exchange reaction by generating hardly soluble silver halide (I) as a by-product. However, silver (I) tetrafluoroborate, which is a starting material, is expensive, but has a large formula weight and therefore needs to be used in large quantities. For this reason, it has been found that there is room for further improvement in terms of production cost.

  Further, in Patent Document 1, a strongly basic ionic liquid is obtained by reacting an ionic liquid with an alcoholate or a bicarbonate, and the ionic liquid is neutralized with an acid. Reporting method. However, it has been found that such a production method has room for further improvement in terms of the purity of the ionic liquid to be produced, and further in terms of production cost.

  This invention is made | formed in view of the said situation, The objective is to provide the manufacturing method which can provide a highly purified ionic compound efficiently with high productivity.

  In order to solve the above-mentioned problems, the present inventors have intensively studied paying attention to a source of anion species that can constitute an ionic compound in an anion exchange reaction. As a result, a conjugate acid is used as a source of anionic species that can constitute an ionic compound, and generation of inorganic salts that are difficult to remove as a by-product is eliminated, and it is generated as a by-product instead of the inorganic salt. It has been found that the target ionic compound can be produced with high purity and high productivity by carrying out the anion exchange reaction while removing the hydrogen halide gas. The present invention has been made as a result of the above-described studies, and achieves the above-described object with the following configuration.

That is, the present invention provides the following general formula (1);
[A ⁺ ] [X ⁻ ] (1)
(In formula (1), [A ⁺ ] is at least one cation species selected from the group consisting of ammonium cations or phosphonium cations, and [X ⁻ ] is an anion species consisting of halide ions). The present invention relates to a method for producing an ionic compound, comprising an anion exchange reaction between a ionic compound precursor to be conjugated and a conjugate acid.

In the conventional method, an anion exchange reaction of an ionic compound precursor is performed using a metal-containing reagent such as NaBF ₄ (see [Chemical Formula 2]), and by removing inorganic salts as by-products, the equilibrium is obtained. An anion exchange reaction, which is a reaction, proceeded. However, it is difficult to remove the inorganic salt from the ionic compound, and as described above, there was a limit to increasing the yield of the ionic compound and increasing its purity.

  On the other hand, in the production method according to the present invention, a conjugate acid is used in the anion exchange reaction. As a result, in the anion exchange reaction, what is replicated together with the ionic compound is not an inorganic salt but a hydrogen halide gas. The hydrogen halide gas easily evaporates from the reaction system, and further, when alcohol is present in the reaction system, it reacts with it to give a highly volatile alkyl halide. Is more efficient. Thereby, the anion exchange reaction which is an equilibrium reaction tends to proceed in the direction in which the ionic compound is generated. Moreover, since both the hydrogen halide gas and the alkyl halide are highly volatile, they can be easily separated and removed from the ionic compound. As a result, in the production method according to the present invention, an ionic compound can be produced easily with a high yield and with a high purity.

  In the above production method, the anion exchange reaction is preferably carried out while removing a hydrogen halide gas produced as a by-product. As described above, since the anion exchange reaction is an equilibrium reaction, in order to efficiently produce the target ionic compound, a device for efficiently removing the by-product from the reaction system is required. In the present invention, since the hydrogen halide gas as a by-product is a gas, it can be efficiently removed from the reaction system. Furthermore, when alcohol is present in the reaction system, the hydrogen halide gas reacts with the alcohol to give a highly volatile alkyl halide, so that the removal of the hydrogen halide gas from the reaction system is more efficient. It becomes. Therefore, according to such synthesis, it is possible to produce an ionic compound with higher yield and higher purity. As a method for removing the hydrogen halide gas and the alkyl halide, a method known to those skilled in the art, such as distillation under reduced pressure, can be employed.

  In the production method, the anion exchange reaction is preferably carried out at a moisture content of 1100 ppm or less. The hydrogen halide gas by-produced in the anion exchange reaction forms a hydrogen halide-water azeotrope and raises its boiling point when water is present in the reaction system. It tends to be difficult to remove. However, when the anion exchange reaction is performed at a low moisture content, specifically, for example, when the anion exchange reaction is performed in a state where the moisture content is maintained at 1100 ppm or less, the boiling point of the hydrogen halide gas is increased by azeotropy with water. Is more reliably prevented, and the removal of hydrogen halide gas from the reaction system becomes easier. In addition, since the by-product in the production of alkyl halide by the reaction of hydrogen halide gas and alcohol is water, this reaction is promoted by reducing the moisture content in the reaction system, and as a result, the halogen from the reaction system is reduced. Removal of hydride gas becomes easier. As a result, an ionic compound can be produced more easily and with a high yield and with a higher purity.

  In the above production method, the anion exchange reaction is preferably carried out in the presence of at least one selected from the group consisting of orthoesters and acetals. In the anion exchange reaction, the ortho ester and / or acetal functions as a solvent, and quickly decomposes water present in the reaction system under acidic conditions to produce an alcohol and a carboxylic acid ester, or a ketone or an aldehyde. As a result, the moisture content in the reaction system can be significantly reduced, so that the boiling point of the hydrogen halide gas due to azeotropy with water can be prevented, and the removal of the hydrogen halide gas becomes easier. In addition, when an alcohol is present in the reaction system, the hydrogen halide gas reacts with it to produce an alkyl halide, but the by-product produced in this reaction is water, so the moisture content in the reaction system This reaction is promoted by the reduction of hydrogen, and as a result, the removal of hydrogen halide gas from the reaction system becomes easier. As a result, an ionic compound can be produced more easily and with a high yield and with a higher purity. In the present invention, it is preferable to use orthoesters among orthoesters and acetals from the viewpoint of cost. Among orthoesters, trialkyl orthoformate, trialkyl orthoacetate and trialkyl orthopropionate are selected. It is more preferable to use at least one kind.

  In the above production method, the anion exchange reaction is preferably carried out while removing the halogenated alkyl produced as a by-product. As described above, orthoester reacts with water in the reaction system, but alcohol is generated in the decomposition reaction, alcohol reacts with hydrogen halide gas present as a by-product in the reaction system, and alkyl halide is converted. By-product. Therefore, by performing the anion exchange reaction while removing the alkyl halide produced as a by-product, it is possible to produce an ionic compound with higher yield and higher purity.

  In the production method, the cation species is preferably at least one selected from the group consisting of an imidazolium cation, a pyridinium cation and a pyrrolidinium cation, and the conjugate acid is tetrafluoroboric acid, hexafluorophosphorus It is preferably at least one selected from the group consisting of an acid, bis (trifluoromethanesulfonyl) imide and trifluoromethanesulfonic acid.

  In the said manufacturing method, it is preferable that the said anion exchange reaction is implemented by making the said conjugate acid react excessively by molar ratio with respect to the said ionic compound precursor. As described above, since the anion exchange reaction is an equilibrium reaction, it is preferable that the mixing ratio of the ionic compound precursor and the conjugate acid be exactly the same molar ratio, but the mixing ratio is exactly the same in the experimental operation. It is difficult. However, in the present invention, the conjugated acid is intentionally reacted with the ionic compound precursor in excess at a molar ratio, and this is removed while generating hydrogen halide gas, and finally the excess conjugated acid is removed. Also, an anion exchange reaction can be carried out efficiently.

  The production method preferably includes a step of removing the unreacted conjugate acid using a free base type weakly basic anion exchange resin. The free base type weakly basic anion exchange resin does not react with the ionic compound, but selectively reacts with the conjugate acid by the immobilized tertiary amine moiety. Therefore, since it is possible to selectively remove excess conjugate acid present in the reaction system, the ionic compound can be produced in a simpler manner with a higher yield and higher purity.

The method for producing an ionic compound according to the present invention includes an anion exchange reaction between an ionic compound precursor and a conjugate acid. The ionic compound precursor has the following general formula (1):
[A ⁺ ] [X ⁻ ] (1)
(In formula (1), [A ⁺ ] is at least one cation species selected from the group consisting of ammonium cations or phosphonium cations, and [X ⁻ ] is an anion species consisting of halide ions). Is done.

In the formula (1), [A ⁺ ] is at least one cation species selected from the group consisting of an ammonium cation or a phosphonium cation, and is not particularly limited, but examples thereof include a quaternary ammonium cation and an imidazolium. Examples include cations, pyrazolium cations, pyridinium cations, pyrrolidinium cations, triazole cations, quinolium cations, thiazolium cations, triazinium cations, and phosphonium cations.

In the formula (1), [X ⁻ ] is an anion species composed of halide ions, and examples thereof include a fluorine anion, a chlorine anion, a bromine anion, and an iodine anion.

The production process of the ionic compound precursor is not particularly limited, but can be synthesized, for example, by a nucleophilic substitution reaction between various tertiary amines and alkyl halides. As an example, a synthesis example of 1-ethyl-3-methylimidazolium bromide (EMIBr), which is one kind of ionic compound precursor, is shown below. The 1-ethyl-3-methylimidazolium cation corresponds to [A ⁺ ] in the formula (1).

  It is known that the production process of the ionic compound precursor can be carried out in a high yield by reaction for several hours in an autoclave or under heating and refluxing conditions, and there are many reports.

In the method for producing an ionic compound according to the present invention, a conjugate acid is used in the anion exchange reaction of the ionic compound precursor. In the anion exchange reaction, the conjugate acid releases hydrogen ions (H ⁺ ) to react with halide ions in the ionic compound precursor to generate hydrogen halide gas (HX), and the anion species is an ionic compound. Exchanged for halide ions in the precursor. The conjugate acid can be used without particular limitation as long as it can cause an anion exchange reaction with the ionic compound precursor. For example, tetrafluoroboric acid, hexafluorophosphoric acid, bis (perfluoroalkylsulfonyl) imide, bis ( Fluorosulfonyl) imide, perfluoroalkylsulfonic acid, fluorosulfonic acid and perfluorocarboxylic acid. In general, the conjugate acid is often marketed in the form of a concentrated aqueous solution. However, when water is present in the anion exchange reaction system, it is difficult to remove the by-product hydrogen halide gas. Therefore, it is preferable to reduce the moisture content in the conjugate acid as much as possible, or to carry out the anion exchange reaction in the presence of at least one selected from the group consisting of orthoesters and acetals, as will be described later.

As an example, EMIBr is used as an ionic compound precursor, tetrafluoroboric acid is used as a conjugate acid, and an anion exchange reaction is performed. It shows an example of preparing 3-methyl imidazolium (EMIBF _4).

In the above example, the target ionic compound EMIBF ₄ and the by-product HBr are generated by the anion exchange reaction between EMIBr and HBF ₄ . However, since HBr is a gas and easily evaporates from the reaction system, the anion exchange reaction, which is an equilibrium reaction, easily shifts in the direction in which EMIBF ₄ is generated. In the case of coexisting alcohol in the reaction system, to produce a highly volatile alkyl bromide by reaction with HBr, easily stripped from the reaction system, is thereby anion exchange reaction is an equilibrium reaction, EMIBF ₄ It is easy to shift depending on the direction in which As a result, in the above example, EMIBF ₄ which is an ionic compound with high yield and high purity can be easily produced. In the present invention, in order to remove the hydrogen halide gas containing HBr and the alkyl halide that may be generated when alcohol is present in the reaction system, an evaporator or the like is used to remove the hydrogen halide gas and the alkyl halide. Is preferably distilled off under reduced pressure.

  In the production method according to the present invention, as a result of using a conjugate acid for the anion exchange reaction, hydrogen halide gas is generated, but when water is present in the reaction system, a hydrogen halide-water azeotrope is formed, Since the boiling point is increased, removal of the hydrogen halide gas from the reaction system tends to be difficult. Therefore, in order to prevent the high boiling point of the hydrogen halide gas due to azeotropy with water and to facilitate the removal of the hydrogen halide gas from the reaction system, the anion exchange reaction is performed with a moisture content as low as possible. It is preferable to implement. In particular, as shown in the experimental results described later, it is preferable to carry out at a moisture content of 1100 ppm or less. Furthermore, it is more preferable to carry out at a moisture content of 500 ppm or less, and it is more preferred to carry out at a moisture content of 100 ppm or less.

  In the production method according to the present invention, the anion exchange reaction can be carried out using a solvent known to those skilled in the art. However, in the presence of at least one selected from the group consisting of orthoesters and acetals as a solvent and moisture remover in order to carry out the anion exchange reaction under low moisture content conditions, specifically, for example, at a moisture content of 1100 ppm or less. It is preferable to carry out an anion exchange reaction in the presence of an orthoester, and more preferably an anion exchange reaction in the presence of an orthoester. The orthoester can be used without any particular limitation, and examples thereof include orthoalkyl esters such as trialkyl orthoformate, trialkyl orthoacetate and trialkyl orthopropionate.

The orthoester rapidly decomposes water when water is present in the reaction system under acidic conditions. For example, orthoformate ester will be described as an example. Orthoformate quickly decomposes water to produce formate ester and alcohol ([Chemical Formula 5]). Formic acid ester and alcohol are both volatile components and can be distilled off, so that separation from ionic compounds is easy.

（上記において、Ｒは炭素数１〜１０の直鎖、あるいは分岐鎖を有しても良いアルキル基である）

(In the above, R is a linear or branched alkyl group having 1 to 10 carbon atoms)

  Furthermore, when hydrogen halide is present in the reaction system, alcohol by-produced by the decomposition of water may react with hydrogen halide to produce alkyl halide. As an example, the decomposition reaction of water of orthoformate in the presence of hydrogen halide gas is shown ([Chemical Formula 6]).

（上記において、Ｒは炭素数１〜１０の直鎖、あるいは分岐鎖を有しても良いアルキル基である）

(In the above, R is a linear or branched alkyl group having 1 to 10 carbon atoms)

  In the above decomposition reaction, an alkyl halide is generated as a by-product in addition to the hydrogen halide gas by an anion exchange reaction and a water decomposition reaction with orthoformate. However, since the alkyl halide is also volatilized, it can be easily removed from the reaction system.

  When the anion exchange reaction is carried out in the presence of at least one selected from the group consisting of orthoesters and acetals, the temperature conditions are not particularly limited. However, when an ionic compound precursor and, for example, an orthoester are mixed, the reaction system is cooled on, for example, an ice bath, and an anion exchange reaction is performed while adding a conjugate acid dropwise thereto. Can be prevented.

  Since the anion exchange reaction carried out in the production method according to the present invention is an equilibrium reaction, it is preferable that the mixing ratio of the ionic compound precursor and the conjugate acid be exactly the same molar ratio. It is difficult to make the ratios exactly the same. However, in the present invention, the conjugated acid is intentionally reacted with the ionic compound precursor in excess at a molar ratio, and this is removed while generating hydrogen halide gas, and finally the excess conjugated acid is removed. Also, an anion exchange reaction can be carried out efficiently. In order to efficiently produce the ionic compound, the molar ratio of the conjugate acid to the ionic compound precursor is preferably 1.003 or more, and more preferably 1.005 or more. On the other hand, even if the conjugated acid is used in an excessive amount, not only the raw material cost increases but also the removal burden increases. Therefore, the upper limit of the molar ratio of the conjugate acid is preferably about 1.05 or less, for example.

  As described above, in the present invention, it is possible to cause the conjugate acid to be excessively reacted with the ionic compound precursor in a molar ratio, but it is necessary to finally remove the conjugate acid from the ionic compound. . As such a removing means, the production method according to the present invention preferably includes a step of using a free base type weakly basic anion exchange resin to remove unreacted conjugate acid. The free base type weakly basic anion exchange resin does not react with the ionic compound, but selectively reacts with the conjugate acid by the immobilized tertiary amine moiety. Therefore, since it is possible to selectively remove excess conjugate acid present in the reaction system, the ionic compound can be produced in a simpler manner with a higher yield and higher purity. As for the free base type weakly basic anion exchange resin, for example, J. Org. Chem. Eng. Data, 2012, 57, 3497-2502. Those described in (1) can be preferably used.

The ionic compound that can be produced by the production method according to the present invention can be represented, for example, by the following general formula (2).
[A ⁺ ] [Y ⁻ ] (2)
(In Formula (2), [A ⁺ ] is at least one cation species selected from the group consisting of an ammonium cation and a phosphonium cation. Examples of [Y ⁻ ] include BF ₄ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ⁻ , CF ₃ CF ₂ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , CF ₃ COO ⁻ , and the anionic species described in the following general formulas (3) to (6) can be given.

General formula (3):
(C _n F _{2n + 1} SO ₂ ) ₂ N ⁻ (3)
(In general formula (3), n is an integer of 0 to 10), general formula (4):
_{CF 2 (C m F 2m SO} 2) 2 N - (4)
(In general formula (4), m is an integer of 0 to 10), general formula (5):
⁻ O ₃ S (CF ₂ ) ₁ SO ₃ ⁻ (5)
(In general formula (5), l is an integer of 1 to 10), general formula (6):
^{_{(C p F 2p + 1 SO}} 2) N - (C q F 2q + 1 SO 2) (6)
(In general formula (6), p and q are integers of 0 to 10).

Specific examples of the anion species represented by the general formula (3) include bis (heptafluoropropanesulfonyl) imide anion, bis (nonafluorobutanesulfonyl) imide anion, and bis (undecafluoropentanesulfonyl) imide anion. Bis (tridecafluorohexanesulfonyl) imide anion, bis (pendadecafluoroheptanesulfonyl) imide anion, and the like. Among these, bis (heptafluoropropanesulfonyl) imide anion or bis (nonafluorobutanesulfonyl) imide anion is particularly preferable.

Specific examples of the anion species represented by the general formula (4) include cyclo-hexafluoropropane-1,3-bis (sulfonyl) imide anion, which can be suitably used.

Specific examples of the anion species represented by the general formula (5) include a hexafluoropropane-1,3-disulfonic acid anion, which can be suitably used.

Specific examples of the anion species represented by the general formula (6) include trifluoromethanesulfonyl nonafluorobutanesulfonylimide anion, heptafluoropropanesulfonyltrifluoromethanesulfonylimide anion, pentafluoroethanesulfonyl nonafluorobutanesulfonylimide anion. Etc., and can be suitably used.

  In the method for producing an ionic compound according to the present invention, a high-purity ionic compound can be efficiently provided with high productivity. Therefore, it is useful in, for example, the battery field, the organic synthesis field, the space material field, and the nuclear power field that require high-purity ionic compounds. Furthermore, the method for producing an ionic compound according to the present invention can provide a high-purity ionic compound at a lower cost than the conventional method. Therefore, it is also very useful for technical applications using a large amount of ionic compounds, for example, an adhesive used when sticking a polarizing film to a liquid crystal cell, or an antistatic application added to plastics. In particular, when an ionic compound produced by the method for producing an ionic compound according to the present invention is added to prevent the pressure-sensitive adhesive, the ionic compound has few impurities and has a high purity. The deterioration of characteristics can be prevented.

  Examples of the present invention will be described below, but the embodiments of the present invention are not limited thereto. In addition, when implementing a present Example, the various measuring methods utilized are shown below.

<Proton nuclear magnetic resonance method>
A JNM-ECX-400P FT NMR apparatus (manufactured by JEOL Ltd.) was used, and dimethyl sulfoxide-d6 was used as a solvent, tetramethylsilane was used as a reference substance, and measurement was performed at room temperature by a method known to those skilled in the art.

<Fluorine-19 nuclear magnetic resonance method>
A method known to those skilled in the art at room temperature using a JNM-ECX-400P FT NMR apparatus (manufactured by JEOL Ltd.), using dimethyl sulfoxide-d6 as a solvent and sodium tetrafluoroborate dissolved in heavy water as a reference substance Measurement was carried out by

<Fluorescence X-ray analysis>
Using a ZSX Primus II wavelength dispersive X-ray fluorescence analyzer (manufactured by Rigaku Co., Ltd.), rhodium was used as an X-ray source at room temperature by a method known to those skilled in the art.

Reference Example In order to confirm the moisture content reduction effect by orthoester in anion exchange reaction, the following preliminary examination was performed.

In 40 ml of triethyl orthoformate, 65 mmol of EMIBr and 66 mmol of tetrafluoroboric acid (HBF ₄ ) aqueous solution (48% by weight) (1% excess by mol with respect to EMIBr) were mixed in a cooled state on an ice bath. When the time change of the moisture content was measured in the reaction solution by the Karl Fischer method, the initial moisture content was 10 ⁵ ppm, whereas the moisture content was reduced to 1,100 ppm immediately after mixing.

Example 1
In a 200 mL eggplant-shaped flask, 100 mL of triethyl orthoformate was added to 30.76 g of 1-butyl-3-methylimidazolium bromide, and this mixture was vigorously magnetically stirred in an ice bath with an aqueous tetrafluoroboric acid (HBF ₄ ) solution ( 48 wt%) 25.78 g was added dropwise. In addition, when the moisture content during reaction was measured by the same method as the above-mentioned reference example, moisture was not detected (approximately 0 ppm). Volatile components in the obtained mixture were distilled off with a rotary evaporator. Triethyl orthoformate (100 mL) was added to the residue and stirred, and then the volatile component was distilled off again with a rotary evaporator. The resulting liquid formed two layers, of which the lower layer was transferred to another 100 mL eggplant-shaped flask. This was heated under reduced pressure to further distill off the remaining volatile components. The obtained crude product was mixed with 30 mL of water and stirred well, and then 2.26 g of Dowex Marathon WBA, which is a kind of free base type weakly basic anion exchange resin, was added. After confirming that the pH of the solution was in the vicinity of neutrality using pH test paper, activated carbon was added for decolorization treatment. Free base type weakly basic anion exchange resin and activated carbon were removed by filtration, and water in the obtained liquid was removed by heating under reduced pressure. As a result, the target ionic compound 1-butyl-3-methylimidazolium tetrafluoroborate ([Chem. 7]) was obtained as an almost colorless and transparent oily substance, and the yield was 28.69 g (yield: 90%). The molecular skeleton was confirmed by proton and fluorine-19 nuclear magnetic resonance. The residual bromide ion concentration was measured by fluorescent X-ray analysis and found to be 62 ± 36 ppm.

Example 2
By following the same procedure as in Example 1 starting from 1-ethyl-3-methylimidazolium bromide and tetrafluoroboric acid solution (48% by weight) (1% by weight), tetrafluoroborate 1-ethyl-3-methylimidazolium ( [Chemical Formula 8]) was obtained as an almost colorless and transparent oily substance, and the yield was 11.77 g (yield: 91%). The molecular skeleton was confirmed by proton and fluorine-19 nuclear magnetic resonance. The residual bromide ion concentration was measured by fluorescent X-ray analysis and found to be 268 ± 55 ppm.

Example 3
1-Butyl-3-methylimidazolium hexafluorophosphate was prepared by following the same procedure as in Example 1 using 1-butyl-3-methylimidazolium bromide and hexafluorophosphoric acid solution (65% by weight) as starting materials. [Chemical 9]) was obtained as a slightly brown oily substance, and the yield was 5.71 g (yield: 83%). The molecular skeleton was confirmed by proton and fluorine-19 nuclear magnetic resonance. The residual bromide ion concentration was measured by fluorescent X-ray analysis and found to be 172 ± 41 ppm.

Example 4
By following the same procedure as in Example 1 using 1-ethyl-3-methylimidazolium bromide and bis (trifluoromethanesulfonyl) imide as starting materials, 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide ( [Chemical Formula 10]) was obtained as a brown oily substance, and the yield was 14.4 g (yield: 63
%)Met. The molecular skeleton was confirmed by proton and fluorine-19 nuclear magnetic resonance. The residual bromide ion concentration was measured by fluorescent X-ray analysis and found to be 88 ± 40 ppm.

Example 5
By following the same procedure as in Example 1 using N-butylpyridinium bromide and tetrafluoroboric acid solution (48% by weight) as starting materials, N-butylpyridinium tetrafluoroborate ([Chem. 11]) was slightly browned. Obtained as an oily substance, the yield was 25.05 g (yield: 80%). The molecular skeleton was confirmed by proton and fluorine-19 nuclear magnetic resonance. The residual bromide ion concentration was measured by fluorescent X-ray analysis and found to be 217 ± 35 ppm.

Example 6
By following the same procedure as in Example 1 using 1-ethyl-3-methylimidazolium bromide and trifluoromethanesulfonic acid as starting materials, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([Chemical Formula 12]) was obtained. Obtained as a colorless oily substance, the yield was 10.83 g (yield: 61%). The molecular skeleton was confirmed by proton and fluorine-19 nuclear magnetic resonance. The residual bromide ion concentration was measured by fluorescent X-ray analysis and found to be 146 ± 56 ppm.

Example 7
1-Butyl-1-methylpyrrolidinium bis (trifluoromethanesulfonyl) was prepared by following the same procedure as in Example 1 starting from 1-butyl-1-methylpyrrolidinium bromide and bis (trifluoromethanesulfonyl) imide. An imide ([Chemical Formula 13]) was obtained as a colorless oily substance, and the yield was 12.83 g (yield: 7
0%). The molecular skeleton was confirmed by proton and fluorine-19 nuclear magnetic resonance. The residual bromide ion concentration was measured by fluorescent X-ray analysis and found to be 93 ± 38 ppm.

Claims (9)

The following general formula (1);
[A ⁺ ] [X ⁻ ] (1)
(In formula (1), [A ⁺ ] is at least one cation species selected from the group consisting of an ammonium cation and a phosphonium cation, and [X ⁻ ] is an anion species consisting of halide ions)
In looking containing an anion exchange reaction between ionic compound precursor and a conjugated acid represented,
The method for producing an ionic compound , wherein the anion exchange reaction is carried out in the presence of an orthoester .   The method for producing an ionic compound according to claim 1, wherein the anion exchange reaction is carried out while removing a hydrogen halide gas produced as a by-product.   The method for producing an ionic compound according to claim 1 or 2, wherein the anion exchange reaction is carried out at a moisture content of 1100 ppm or less. The method for producing an ionic compound according to any one of claims 1 to 3, wherein the orthoester is at least one selected from the group consisting of trialkyl orthoformate, trialkyl orthoacetate and trialkyl orthopropionate. The method for producing an ionic compound according to any one of claims 1 to 4 , wherein the anion exchange reaction is carried out while removing an alkyl halide produced as a by-product. Method for producing a cationic species, imidazolium cation, an ionic compound according to any one of claims 1 to 5, at least one selected from the group consisting of pyridinium cation and pyrrolidinium cation. The said conjugate acid is at least 1 sort (s) selected from the group which consists of tetrafluoroboric acid, hexafluorophosphoric acid, bis (trifluoromethanesulfonyl) imide, and trifluoromethanesulfonic acid, The claim 1 in any one of Claims 1-6 . A method for producing an ionic compound. The method for producing an ionic compound according to any one of claims 1 to 7 , wherein the anion exchange reaction is carried out by reacting the conjugate acid excessively in a molar ratio with the ionic compound precursor. The method for producing an ionic compound according to any one of claims 1 to 8 , comprising a step of removing the unreacted conjugate acid using a free base type weakly basic anion exchange resin.