JP2017200889A - Method for producing ionic liquid and method for producing intermediate body for production of ionic liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an ionic liquid for synthesizing a desired ionic liquid with high purity and a method for producing an intermediate for synthesizing the ionic liquid. A method for producing an ionic liquid according to the present invention is a method for producing a desired ionic liquid Q + Z− comprising a cation Q + and an anion Z−, which comprises recrystallization from a cation Q + and an anion Y−. A step of purifying a high melting point intermediate Q + Y− having a possible melting point by recrystallization, and a step of obtaining an ionic liquid Q + Z− directly or indirectly from the high melting point intermediate Q + Y− after the purification. Including. The method for producing a strong base intermediate or superhydrophilic intermediate of the present invention comprises a step of obtaining a strong base intermediate or superhydrophilic intermediate from the high-melting intermediate Q + Y- after purification by metathesis precipitation. Or a step of obtaining a strongly basic intermediate from the purified high melting point intermediate Q + Y- by metathesis precipitation, and a step of obtaining a superhydrophilic intermediate from the strong base intermediate by a neutralization method, including. [Selection] Figure 1

Description

  The present invention relates to a method for producing an ionic liquid and a method for producing an intermediate for producing an ionic liquid.

The ionic liquid refers to a group of substances that take a liquid state near room temperature (generally, 100 ° C. or lower or 150 ° C. or lower) among substances whose components are only ions.
Ionic liquids have unique properties such as maintaining a liquid state over a wide temperature range, high heat resistance, low vapor pressure, generally non-volatile, high electrical conductivity, and a wide potential window. It is expected to be used in various fields as a third liquid that is different from both organic solvents.
Specifically, it has been studied for use as an electrochemical device due to its electrochemical characteristics, and as a solvent because it has low environmental impact and high heat resistance, and as a lubricating oil using friction characteristics. Utilization and utilization as a carbon dioxide-absorbing liquid using the adsorptive properties (for example, see Patent Document 1) have been studied.

  By the way, it is usually difficult to synthesize an ionic liquid having a desired cation and anion in one operation. Cationic sites such as phosphonium and ammonium are usually synthesized using organic synthesis techniques. In practice, however, specific anions (usually chloride, bromide, iodide ion, alkyl carbonate, etc.) are used depending on the synthesis raw material used. Ions, alkyl sulfate ions) are also obtained in the form of salts. In general, an ionic liquid having a desired cation and an anion is produced by performing an operation of converting an unnecessary anion of the precursor into a desired anion using such a salt as a precursor.

As a procedure for obtaining a desired anion from a precursor, for example, the following is known.
That is, a method of obtaining a desired ionic liquid by synthesizing an alkyl hydrogencarbonate type precursor and neutralizing with a conjugate acid of a desired anion or reacting with an alkaline earth metal salt having the desired anion. It is known (see Patent Document 2).

  Also, a method for obtaining a desired ionic liquid by converting a precursor into an OH type intermediate using an ion exchange resin and neutralizing the OH type intermediate with a conjugate acid of a desired anion is known. (See Non-Patent Document 1).

  Also, an alkyl sulfate type precursor is synthesized, hydrolyzed to form a hydrogen sulfate type intermediate, and then reacted with a strong alkali to obtain an OH type intermediate, followed by conjugation of a desired anion. A method of obtaining a desired ionic liquid by neutralization with an acid is known (see Non-Patent Document 2).

  Further, by reacting an alkali metal salt of para-t-butylphenol with a halogen-type precursor, a para-t-butylphenoxide type intermediate is synthesized, neutralized with a conjugate acid of a desired anion, A method is known in which a desired ionic liquid is obtained by extracting and removing a produced alkylphenol in an organic solvent (see Non-Patent Document 3).

Japanese Patent Laying-Open No. 2015-71152 U.S. Pat. No. 8,075,803

Kenta Fukumoto, Masahiro Yoshizawa and Hiroyuki Ohno, “Room Temperature Ionic Liquids from 20 Natural Amino Acids”, J. Am. Chem. Soc, 127, 2398-2399 (2005) Jamie L. Ferguson, John D. Holbrey, Shieling Ng, Natalia V. Plechkova, Kenneth R. Seddon, Alina A. Tomaszowska and David F. Wassell, “A greener, halide-free approach to ionic liquid synthesis”, Pure Appl. Chem., Vol84, pp723-744 (2011) Kallidanthiyil Chellappan Lethesh, Dries Parmentier, Wim Dehaen and Koen Binnemans, “Phenolate platform for anion exchange in ionic liquids”, RSC Advances., Vol.2, pp.11936-11943 (2012)

Since ionic liquids have the above-mentioned unique characteristics, they are expected to be used in various applications. On the other hand, general purification techniques such as distillation and recrystallization are applied because of their unique characteristics. Difficult to do.
However, none of the above-described synthesis techniques has studied a method for increasing the purity of the obtained ionic liquid. In any case, if the purity of the precursor is poor, a high-purity ionic liquid cannot be obtained.
Therefore, it has been difficult to synthesize high purity (for example, more than 99%) ionic liquids by conventional synthesis methods.
As described above, since the conventional synthesis method is not sufficiently purified, the ionic liquid is colored due to the presence of impurities, an unpleasant odor is generated, the potential window is narrowed, and the heat resistance is reduced. It was.

  Therefore, an object of the present invention is to provide a method for producing an ionic liquid for synthesizing a desired ionic liquid with high purity and a method for producing an intermediate for synthesizing such an ionic liquid.

The present inventor has intensively studied to solve the above-mentioned problems, and in producing a desired ionic liquid Q ⁺ Z ⁻ comprising a cation Q ⁺ and an anion Z ^−, highly purified by causing through the purification process by, a high-purity refractory intermediates after purification steps object of the ionic liquid Q ⁺ Z ^- if it is converted into a high purity ionic liquids which can not be conventionally achieved It has been found that Q ⁺ Z ⁻ can be obtained.
Also, a refractory intermediate high purity objective ionic liquid Q ⁺ Z ^- can be converted to the, even through a strong base-type intermediate and superhydrophilic type intermediates, ionic liquids are highly purified above a certain It has also been found that Q ⁺ Z ⁻ can be obtained.
The present invention has been completed through the above knowledge and confirmation based on experiments.

That is, the method for producing an ionic liquid according to the present invention is a method for producing a desired ionic liquid Q ⁺ Z ⁻ comprising a cation Q ⁺ and an anion Z ⁻ , which can be recrystallized comprising a cation Q ⁺ and an anion Y ^−. A step of purifying a high melting point intermediate Q ⁺ Y ⁻ having a high melting point by recrystallization, and a step of obtaining an ionic liquid Q ⁺ Z ⁻ directly or indirectly from the high melting point intermediate Q ⁺ Y ⁻ after the purification. .

A method for producing an ionic liquid intermediate according to the present invention relates to a method for producing an intermediate for producing the ionic liquid Q ⁺ Z ⁻ , and a method for producing a strong base intermediate and a superhydrophilic intermediate. Two manufacturing methods are included.
That is, among the processes for producing an ionic liquid intermediate according to the present invention, a strong base intermediate is produced by a high-melting intermediate Q ⁺ Y comprising a cation Q ⁺ and an anion Y ⁻ and having a recrystallizable melting point. ^And a step of obtaining a strongly basic intermediate Q ⁺ A ⁻ from the high-melting intermediate Q ⁺ Y ⁻ after the purification by a metathetical precipitation method.
Among the methods for producing an ionic liquid intermediate according to the present invention, a superhydrophilic intermediate is produced by a high-melting intermediate Q ⁺ Y comprising a cation Q ⁺ and an anion Y ⁻ and having a recrystallization melting point. ^- a step of purification by recrystallization, the refractory intermediate Q ⁺ Y after purification ^- strong base-type intermediate Q ⁺ a by a double decomposition precipitation method ^- obtaining a, the strong base type intermediate Q ⁺ a ^- superhydrophilic type intermediate Q ⁺ B by neutralization from ^- or so as to obtain a, cation Q ⁺ and an anion Y ^- refractory intermediates having a re-crystallizable melting point consists Q ⁺ Y ^- recrystallization And a step of obtaining a superhydrophilic intermediate Q ⁺ B ⁻ from the high-melting intermediate Q ⁺ Y ⁻ after the purification by a metathetical precipitation method.

  According to the method for producing an ionic liquid of the present invention, a desired ionic liquid can be synthesized with high purity.

According to the method for producing an ionic liquid intermediate of the present invention, a strongly basic intermediate Q ⁺ A ⁻ or a superhydrophilic intermediate Q ⁺ B ⁻ that can be easily converted into a high purity ionic liquid Q ⁺ Z ⁻ is obtained. Can be manufactured. When the ionic liquid Q ⁺ Z ⁻ is not suitable for storage or transportation, it can be stored or transported as a strong base intermediate Q ⁺ A ⁻ or a superhydrophilic intermediate Q ⁺ B ⁻ .

It is process drawing which shows four embodiment (1st-4th route) regarding the manufacturing method of the ionic liquid of this invention. FIG. 3 is a diagram showing NMR measurement results of a high-melting-point intermediate in Example 1. FIG. 3 is a diagram showing NMR measurement results of an ionic liquid as a target object in Example 1. FIG. 4 is a diagram showing a result of NMR measurement of a high melting point intermediate in Example 2. It is a figure which shows the NMR measurement result of the ionic liquid which is the target object in Example 2. FIG. FIG. 4 is a diagram showing a result of NMR measurement of a high melting point intermediate in Example 3. It is a figure which shows the NMR measurement result of the ionic liquid which is the target object in Example 3. FIG. FIG. 6 is a diagram showing NMR measurement results of a high melting point intermediate in Example 4. It is a figure which shows the NMR measurement result of the ionic liquid which is the target object in Example 4. FIG. FIG. 6 is a diagram showing the NMR measurement result of the superhydrophilic intermediate in Example 5. It is a figure which shows the NMR measurement result of the ionic liquid which is the target object in Example 5. FIG. FIG. 6 is a diagram showing NMR measurement results of a superhydrophilic intermediate in Example 6.

  Hereinafter, preferred embodiments of a method for producing an ionic liquid and a method for producing an intermediate for producing an ionic liquid according to the present invention will be described in detail, but the scope of the present invention is not limited to these descriptions, and Other than the above examples, modifications can be made as appropriate without departing from the spirit of the present invention.

In the following, first, the significance of the cation Q ^{+ and the} anions Z ⁻ , Y ⁻ , X ⁻ , A ⁻ and B ^{− in} the method for producing an ionic liquid and the method for producing an intermediate for producing the ionic liquid according to the present invention will be described. After clarifying, each step will be described in detail.

[Significance of Cation Q ^{+ and} Anions Z ⁻ , Y ⁻ , X ⁻ , A ⁻ and B ⁻ ]
As described later, the present invention is applied to the production of an ionic liquid Q ⁺ Z ⁻ comprising a cation Q ⁺ and an anion Z ⁻ , and a high melting intermediate Q ⁺ Y ⁻ having a recrystallization melting point is obtained. It is essential to go through a purification step for purification.
The high melting point intermediate Q ⁺ Y ⁻ can be obtained, for example, from an ionic liquid precursor Q ⁺ X ⁻ composed of a cation Q ⁺ and an anion X ⁻ .
Further, from the high melting point intermediate Q ⁺ Y ⁻ , a strong base intermediate Q ⁺ A ⁻ and a superhydrophilic intermediate Q ⁺ B ⁻ for the production of the ionic liquid Q ⁺ Z ⁻ can be obtained.

Here, what ions are the object of the present invention as these cations and anions (Q ⁺ , Z ⁻ , Y ⁻ , X ⁻ , A ⁻ , B ⁻ ) of the ionic liquid Q ⁺ Z ⁻ in the present invention. It should be relatively understood in relation to a series of manufacturing processes.

For example, in the purification step of the present invention, a high melting intermediate Q ⁺ Y ⁻ having a recrystallizable melting point is purified. Accordingly, those having no recrystallization melting point do not correspond to the high melting point intermediate Q ⁺ Y ⁻ in the present invention. However, whether or not it has a recrystallization melting point is determined not only by one of the cation and the anion but also by the combination of the cation and the anion. Thus, it cannot be uniformly discussed whether or not a certain cation hits the cation Q ^{+ according} to the present invention, focusing only on the cation. The same applies to whether an anion hits the anion Y ⁻ in the present invention.

The anion X ⁻ is derived from a synthetic raw material used in organic synthesis for obtaining the cation Q ⁺ , and the type of anion is specified within the limits.
Further, the anion Z ⁻ differs depending on whether or not the ionic liquid Q ⁺ Z ⁻ is used as a target, and the ionic liquid having a desired purity is directly or indirectly derived from the purified high melting point intermediate Q ⁺ Y ^−. Any anion can be used as long as Q ⁺ Z ⁻ can be obtained.

Further, the anion A ⁻ may be selected from those that are strongly basic and can be easily exchanged for other anions Z ⁻ by a neutralization reaction.
Furthermore, the anion B ⁻ gives a superhydrophilic intermediate Q ⁺ B ⁻ which has a high hydrophilicity and easily migrates to an aqueous layer upon oil-water extraction. anion Z ^- may be selected those which can be exchanged, in the limit, is any anion.

Thus, the cation or anion (Q ⁺ , Z ⁻ , Y ⁻ , X ⁻ , A ⁻ , B ⁻ ) according to the present invention is a series of processes for producing the ionic liquid Q ⁺ Z ⁻ from the above viewpoint. Insofar as it is understood that the present invention is applicable to the present invention, it refers to any cation or anion.
In addition, in the description of these cations and anions, the superscript “+” or “−” merely means positive or negative charge, and does not imply any limitation to a monovalent cation or anion. That is, in the present invention, when expressed as Q ⁺ , Z ⁻ , Y ⁻ , X ⁻ , A ⁻ , B ⁻ or the like, a polyvalent cation or anion is also conceptually included.

  In the present invention, one of the important features is that a high melting point intermediate having a recrystallization melting point is obtained. However, the combination of a cation and an anion that gives a high melting point intermediate having a recrystallization melting point is as follows. Those skilled in the art can deduce from the disclosure of a plurality of embodiments in the present specification and the structures and electronic states of cations and anions, and can easily confirm the melting point by measuring the melting point. Does not require undue trial and error.

[Ionic liquid Q ⁺ Z ⁻ which is an object of the production method of the present invention]
The ionic liquid Q ⁺ Z ⁻ that provides the production method in the present invention includes, for example, a polyatomic cation Q ⁺ having a structure in which one or more alkyl groups are added to carbon, nitrogen, phosphorus, sulfur atoms, etc. A salt composed of an anion Z ⁻ , in particular, a tetraalkylphosphonium salt ionic liquid (general formula (1)) represented by the following general formulas (1) to (7), a tetraalkylammonium salt ionic liquid ( In addition to general formula (2)), pyrrolidinium salt ionic liquid (general formula (3)), piperidinium salt ionic liquid (general formula (4)), imidazolium salt ionic liquid (general formula (5)), tropylium Preferred examples include salt-based ionic liquid (general formula (6)), pyridinium salt-based ionic liquid (general formula (7)), and the like.
In the following general formulas (1) to (7), R _{1 to} R ₇ and X _{1 to} X ₃ are each independently hydrogen or an alkyl group.

  Many of these salts have a melting point of 100 ° C. or less, but those having no melting point (in the solid state and decompose when heated) are also included in the object of the present invention.

〔Manufacturing process〕
Several routes can be considered for the method for producing an ionic liquid and the method for producing an intermediate for producing the ionic liquid according to the present invention. A process diagram is shown in FIG.

An example shown in FIG. 1 is a step of obtaining a high melting point intermediate Q ⁺ Y ⁻ from an ionic liquid precursor Q ⁺ X ⁻ by an anion exchange method (hereinafter referred to as “step A”), a high melting point intermediate Q ⁺ Y ^−. Is purified by recrystallization to obtain a highly purified high melting intermediate Q ⁺ Y ⁻ (hereinafter referred to as “Step B”).

From the high-melting-point intermediate Q ⁺ Y ⁻ after purification, the target ionic liquid Q ⁺ Z ⁻ can be obtained directly or indirectly.

One possible route is to obtain the ionic liquid Q ⁺ Z ⁻ directly from the purified high melting point intermediate Q ⁺ Y ⁻ by anion exchange (hereinafter referred to as “Step C1”).
Hereinafter, the route that passes through step A, step B, and step C1 is referred to as a “first route”.

Further, as another route, a strongly basic intermediate Q ⁺ A ⁻ is obtained from the purified high melting point intermediate Q ⁺ Y ⁻ by anion exchange (hereinafter referred to as “Step C2”). base form intermediate Q ⁺ a ^- ionic liquid by neutralization from Q ⁺ Z ^- obtaining (hereinafter, referred to as "step D1") is also contemplated that.
Hereinafter, the route that passes through step A, step B, step C2, and step D1 is referred to as a “second route”.

As yet another route, after step C2, superhydrophilic intermediate Q ⁺ B ⁻ is obtained from strong base intermediate Q ⁺ A ⁻ by neutralization (hereinafter referred to as “step D2”). superhydrophilic type intermediate Q ⁺ B ^- ionic liquid Q ⁺ Z by anion exchange method from ^- obtaining (hereinafter, referred to as "step E") below is also conceivable, step a, step B, step C2, step D2, The route that passes through the process E is referred to as a “third route”.

As yet another route, a superhydrophilic intermediate Q ⁺ B ⁻ is obtained from the purified high melting point intermediate Q ⁺ Y ⁻ by anion exchange (hereinafter referred to as “Step C3”). It is also conceivable to obtain ionic liquid Q ⁺ Z ⁻ from the superhydrophilic intermediate Q ⁺ B ⁻ by an anion exchange method in the same manner as in step E of the route of step A, step B, step C3 and step E. The route is referred to as a “fourth route”.

  Hereafter, each said process is explained in full detail.

<Process A: Common to the first to fourth routes>
In step A, a high melting point intermediate Q ⁺ Y ⁻ is obtained from the ionic liquid precursor Q ⁺ X ⁻ by an anion exchange method.
In the example shown in FIG. 1, first, cation Q ⁺ and the anion X ^- ionic liquid precursor consisting Q ⁺ X ^- and from the organic synthesis, the ionic liquid precursor Q ⁺ X ^- a refractory Intermediate Q ⁺ Y ^-Trying to get. However, the ionic liquid precursor Q ⁺ X ⁻ may be already present without depending on the synthesis. Further, it may be recrystallized from an appropriate solvent.
The ionic liquid precursor Q ⁺ X ⁻ is an arbitrary salt having the same cation as the ionic liquid Q ⁺ Z ⁻ to be produced as described above.

Also in the prior art, first, it was common to organically synthesize an ionic liquid precursor having a desired cation (however, conventionally, the target ionic liquid was synthesized from the ionic liquid precursor by an anion exchange method. Therefore, the purity was low).
In the present invention, when organically synthesizing the ionic liquid precursor Q ⁺ X ⁻ , the same synthesis method as in the prior art can be used. For example, an organic molecule and any alkylating agent (alkyl halide, alkyl carbonate) can be used. , Alkyl sulfate, etc.).
In addition, when an ionic liquid having the target cation Q ⁺ already exists and it is desired to recycle or purify it, this can be applied to the present invention as the ionic liquid precursor Q ⁺ X ⁻ .

Specific examples of X ⁻ include halide ions, alkyl carbonate ions, alkyl sulfate ions, hydrogen sulfate ions, hydrogen carbonate ions, sulfate ions, carbonate ions, and the like.

A high melting point intermediate Q ⁺ Y ⁻ can be obtained from the ionic liquid precursor Q ⁺ X ⁻ by anion exchange.

The high melting point intermediate Q ⁺ Y ⁻ has a high melting point due to the combination of Q ⁺ and Y ⁻ and can be purified by recrystallization.
As the anion Y ⁻ , an anion having high hydrophobicity is more advantageous. This is because the conversion from X ⁻ to Y ⁻ can be easily performed by the double decomposition extraction method.
In view of the above viewpoints, the high melting point intermediate Q ⁺ Y ⁻ includes, as the anion Y ^−, four or more halogens (fluorine, bromine) in which the anion Y ⁻ may be different from boron or one or more atoms heavier than boron. , Iodine), an anion having an oxygen atom, an alkyl group or a phenyl group is preferred.
Examples of such anions Y ⁻ include BF ₄ ⁻ , PF ₆ ⁻ , PF ₃ (CF ₂ CF ₃ ) ₃ ⁻ , BPh ₄ ⁻ , (CH ₃ CH ₂ CH ₂ CH ₂ ) ₄ B ⁻ and ClO _4. ^-, such as SiF ₆ ^2-and the like, in _{^{particular, BF 4 -, PF 6 -}} , BPh 4 - are preferred.

As the anion exchange method, for example, a metathesis extraction method can be preferably exemplified.
The double decomposition extraction method can be expressed by the following formula (8). Refractory Intermediate Q ⁺ Y to be obtained ^- and similarly high-melting intermediate raw salt M ⁺ Y anions ^- the ionic liquid precursor Q ⁺ X ^- is contacted with and solvent, and the mixture stirred or shaken to Then, by leaving still, the high-melting-point intermediate Q ⁺ Y ⁻ is extracted into a phase different from the by-product. The salt M ⁺ Y ⁻ used at this time may be a salt produced as a by-product in the subsequent step (step C1 or step C2).

Here, M ⁺ is an arbitrary metal ion. Q ⁺ , X ⁻ and Y ⁻ are as described above.

Specifically, <1> ionic liquid precursor Q ⁺ X ⁻ , <2> water, <3> organic solvent and <4> high melting point intermediate raw material salt M ⁺ Y ⁻ are mixed and stirred or shaken. To do. The order of mixing is not particularly limited.

<3> The organic solvent is preferably an alcohol having 4 or more carbon atoms. However, there is no particular limitation as long as the high melting point intermediate Q ⁺ Y ⁻ can be dissolved and phase-separated from water in that state. For example, dichloromethane, toluene or the like may be used.
In the case where the melting point of the high melting point intermediate Q ⁺ Y ⁻ is not more than room temperature and phase separation with water is performed, <3> an organic solvent is not essential.

<2> Water is preferably used in an amount of about twice that of <1> ionic liquid precursor Q ⁺ X ⁻ on a weight basis.
In addition, <4> high-melting-point intermediate raw material salt M ⁺ Y ⁻ is in a range of about 1.1 to 2.0 equivalents in terms of the amount (mole number) of <1> ionic liquid precursor Q ⁺ X ⁻ . It is preferable to use in. If the amount is too small (particularly less than 1 equivalent), the purity of the target product may be lowered.

Upon standing the mixture, by-products M ⁺ X ^- separated into two layers of an organic layer containing the ^- aqueous layer and the refractory intermediates including Q ⁺ Y. Therefore, the high-melting intermediate Q ⁺ Y ⁻ can be obtained by separating the organic layer and distilling off the solvent as necessary.

In the present invention, the high melting point intermediate Q ⁺ Y ⁻ has a recrystallization melting point and depends on the recrystallization conditions, but considering practicality and the like, for example, the melting point is −30 ° C. or higher. It is preferable that the temperature is 25 ° C. or higher.

<Process B: Common to the first to fourth routes>
In Step B, the high melting point intermediate Q ⁺ Y ⁻ is purified by recrystallization to obtain a highly purified high melting point intermediate Q ⁺ Y ⁻ .

Specifically, for example, the high melting point intermediate Q ⁺ Y ⁻ obtained in step A is dissolved in a solvent such as alcohol at a temperature of room temperature to 50 ° C., and then cooled to an appropriate temperature. Crystals of the melting point intermediate Q ⁺ Y ⁻ can be obtained.

Here, when alcohol is used as a solvent, for example, methanol, ethanol, propanol (including isomers) and the like are preferable.
As the number of carbon atoms increases, the dissolving power decreases. However, the lower the dissolving power, the lower the cooling temperature may not be. Therefore, propanol is often preferred.
However, the high melting point intermediate Q ⁺ Y ⁻ may be insoluble in propanol, in which case ethanol is selected, and in the case of insolubility in ethanol, methanol is selected. In addition, if recrystallization can be performed with high yield in any alcohol, it is conceivable to select the cheapest methanol from the viewpoint of cost.

The cooling temperature may be determined in consideration of the solubility of the high melting point intermediate Q ⁺ Y ⁻ . In general, the lower the temperature, the lower the solubility and the higher the recrystallization yield. It is preferable to select a temperature at which the solubility of the high melting point intermediate Q ⁺ Y ⁻ decreases to around 1% by weight. The number of degrees C. depends on the combination of the high-melting-point intermediate and the solvent, and therefore it may be determined by actually measuring the solubility.
Purity can be further increased by repeating the recrystallization operation a plurality of times.

<Step C1: First route>
The step C1 is a step following the step B in the first route, and an ionic liquid Q ⁺ Z ⁻ as an object can be obtained.
In Step C1, the target ionic liquid Q ⁺ Z ⁻ is obtained from the purified high melting point intermediate Q ⁺ Y ⁻ by an anion exchange method.

As said anion exchange method, the metathesis precipitation method can be mentioned suitably, for example.
The metathesis precipitation method can be represented by the following formula (9), in which <2> anion source N ⁺ Z ⁻ is reacted with <1> high melting point intermediate Q ⁺ Y ⁻ in a solvent.

Here, <2> anion source N ⁺ Z ⁻ is an arbitrary compound having the same anion as the ionic liquid Q ⁺ Z ⁻ to be produced. However, the anion source N ⁺ Z ⁻ is soluble in a solvent similar to the solvent for dissolving the high melting point intermediate Q ⁺ Y ⁻ . Preferred examples of N ⁺ include ions such as potassium, rubidium, cesium, calcium, strontium, and barium, ammonium ions, and tetramethylammonium ions. Q ⁺ , Y ⁻ and Z ⁻ are as described above.
The solvent preferably contains water or alcohol as a main component, and alcohol can be particularly preferably used.

Regarding the selection of N ⁺ and the solvent, for example, the following viewpoints can be considered.
That is, as can be seen from the above formula (9), in the metathesis precipitation method, the lower the solubility of N ⁺ Y ⁻ , the higher the exchange rate of anion exchange. Therefore, it can be said that it is desirable to select N ⁺ so that the solubility of N ⁺ Y ⁻ is as low as possible in order to obtain a higher purity ionic liquid Q ⁺ Z ⁻ .
For reference, the solubility (10 ⁻³ mol / L) at 20 ° C. in each solvent of the precipitated salt N ⁺ Y ⁻ in the metathesis precipitation method is shown in Table 1 (Y ⁻ = BF ₄ ⁻ ) and Table 2 (Y ⁻ = PF ₆ ⁻ ).

As can be seen from Tables 1 and 2, the solubility of N ⁺ Y ⁻ is lower in alcohol than in water, and even in alcohol, the solubility decreases. This can be a guide for solvent selection.
However, in selecting N ⁺ and a solvent, it is necessary to consider whether the <2> anion source N ⁺ Z ⁻ is soluble in the solvent in addition to the solubility of N ⁺ Y ⁻ .

Next, as a specific operation, for example, <1> high-melting-point intermediate Q ⁺ Y ⁻ and <2> anion source N ⁺ Z ⁻ are respectively dissolved in alcohol and mixed at about room temperature.

<2> The anion source N ⁺ Z ⁻ is preferably used in an amount of about 1.2 equivalents in terms of the amount (mole number) relative to the <1> high melting point intermediate Q ⁺ Y ⁻ . If the amount is too small (particularly less than 1 equivalent), the purity of the target product may be significantly reduced. If the amount is too large, the <2> anion source N ⁺ Z ⁻ may be mixed into the target product.

When using alcohol as a solvent, C1-C3 alcohol is preferable and 2-propanol, 1-propanol, and ethanol are especially preferable. Other solvents such as hexane may be added as appropriate for the purpose of lowering the viscosity. If methanol or water is used, precipitation of N ⁺ Y ⁻ in the above formula (9) may be incomplete, and the purity of the target product may be slightly lowered. On the other hand, if a longer-chain alcohol is used than propanol, <2> anion source N ⁺ Z ⁻ may not be sufficiently dissolved and the purity of the target product may be lowered (see also Table 1 and Table 2 above).

Next, <1> refractory Intermediate Q ⁺ Y ^- and <2> an anion source N ⁺ Z ^- precipitated N ⁺ Y generated during mixing ^- was filtered off, cool the filtrate to -20 ℃ ~-85 ℃ It is preferable to perform filtration again. If not cooled, an anion Y ⁻ (such as BF ₄ ⁻ ) of the high melting point intermediate Q ⁺ Y ⁻ may remain in the filtrate. If the cooling temperature is too low, the solution may solidify and may not be filtered.
When the solvent is distilled off from the obtained filtrate, an excess of <2> anion source N ⁺ Z ⁻ (part exceeding 1 equivalent) precipitates in the target ionic liquid Q ⁺ Z ⁻ . This excess of N ⁺ Z ⁻ can be removed, for example, by any of the following methods.
When the ionic liquid Q ⁺ Z ⁻ is insoluble in water, the crude ionic liquid Q ⁺ Z ⁻ containing an excess of N ⁺ Z ⁻ is shaken with water, and then left to stand to separate into two layers. The excess of N ⁺ Z ⁻ is extracted into the aqueous layer and is removed. The object of the ionic liquid Q ⁺ Z ^- if the melting point higher than room temperature, the extraction prior to the operation of the crude ionic liquid Q ⁺ Z ^- a, N ⁺ Z ^- dissolved in does not dissolve the organic solvent (such as dichloromethane) It is necessary to keep it.
Further, when the ionic liquid Q ⁺ Z ⁻ is water-soluble, the crude ionic liquid Q ⁺ Z ⁻ is diluted with a solvent that does not dissolve N ⁺ Z ⁻ (for example, dichloromethane), and then the undissolved N ⁺ Z ⁻ microcrystals Can be removed by filtration.

<Process C2: common to the second and third routes>
Process C2 is a process following process B in the second and third routes.
In Step C2, a strongly basic intermediate Q ⁺ A ⁻ is obtained from the purified high melting point intermediate Q ⁺ Y ⁻ after Step B by an anion exchange method.
This step C2 can be basically performed by the same operation as the step C1, and instead of the anion source N ⁺ Z ⁻ described in the step C1, a metal hydroxide, a metal alkoxide, a metal methide, a metal amide, a metal A strong base intermediate material N ⁺ A ⁻ such as alkyl may be used (see the following formula (10)).

In the strong base type intermediate Q ⁺ A ⁻ , the anion A ⁻ is strongly basic and can be easily exchanged for another anion Z ⁻ by a neutralization reaction.
Preferable examples of A ⁻ include hydroxide ion OH ⁻ , methoxide ion CH ₃ O ⁻ , ethoxide ion CH ₃ CH ₂ O ⁻ , t-butoxide ion (CH ₃ ) ₃ CO ^{− and the} like.

As a specific operation, for example, <1> high melting point intermediate Q ⁺ Y ⁻ and <2> strong base type intermediate raw material N ⁺ A ⁻ are respectively dissolved in alcohol and mixed at about room temperature. About selection of alcohol, it is the same as that of process C1.
It is preferable to filter the precipitate produced as a by-product during mixing, then, for example, add about 0.5 times the amount of hexane or the like to cool the filtrate strongly, and perform filtration again. Since the strong base intermediate Q ⁺ A ⁻ is unstable and cannot be isolated, it is preferable not to concentrate the filtrate.

<Process C3: Fourth route>
Process C3 is a process following process B in the fourth route.
In Step C3, a superhydrophilic intermediate Q ⁺ B ⁻ is obtained from the purified high melting point intermediate Q ⁺ Y ⁻ after Step B by an anion exchange method.
This step C3 can be performed basically by the same operation as in step C1, and instead of the anion source N ⁺ Z ⁻ described in step C1, the anion (B ⁻ ) contains two sulfuric acid, phosphoric acid and two hydroxyl groups. The superhydrophilic intermediate raw material N ⁺ B ⁻ which is a conjugated base such as carboxylic acid may be used (see the following formula (11)).

The super-hydrophilic intermediate Q ⁺ B ⁻ has an anion B ^{− which} is a polyvalent anion or has two or more hydroxyl groups even if it is monovalent. It has the property of easily moving to the water layer when extracted.
The anion B ⁻ of the superhydrophilic intermediate Q ⁺ B ⁻ can be easily exchanged with another anion Z ⁻ by the metathesis extraction method (in the metathesis extraction method, a highly hydrophilic ion can be exchanged for a low ion, but the reverse is true. Can not).
Preferable examples of B ⁻ include sulfate ion SO ₄ ²⁻ , phosphate ion PO ₄ ³⁻ , citrate ion —OOC—CH ₂ —C (OH) (COO ⁻ ) —CH ₂ COO ⁻ , tartrate ion — OOC-CH (OH) -CH ( OH) (COO -), glycolic acid ion CH ₂ (OH) COO ^-, lactate CH ₃ CH (OH) COO ^-, and the like.

As a specific operation, for example, <1> high melting point intermediate Q ⁺ Y ⁻ and <2> superhydrophilic intermediate raw material N ⁺ B ⁻ are respectively dissolved in alcohol and mixed at about room temperature. About selection of alcohol, it is the same as that of process C1. Moreover, the removal of the precipitate generated as a by-product during mixing is the same as in step C1.

<Step D1: Second route>
The process D1 is a process following the process C2 in the second route, and an ionic liquid Q ⁺ Z ⁻ as a target product can be obtained.
Step D1 is a step of neutralizing the strongly basic intermediate Q ⁺ A ⁻ obtained in Step C2 with a conjugate acid HZ of the target anion.
This is just a neutralization reaction, and a conventional general method may be used.

After the neutralization operation is completed, the target ionic liquid can be obtained by distilling off the solvent.
However, in this step D1, the excess (part exceeding 1 equivalent) of <2> strong base type intermediate raw material N ⁺ A ⁻ (see the above formula (10)) in step C2 is acid HZ (target anion). N ⁺ Z ⁻ is generated by neutralization with a conjugated acid. The N ⁺ Z ⁻ is mixed with the target ionic liquid Q ⁺ Z ⁻ and precipitated as a microcrystal. In order to remove this, it can be removed by any of the following methods, for example, as described in the step C1.
When the ionic liquid Q ⁺ Z ⁻ is insoluble in water, the crude ionic liquid Q ⁺ Z ⁻ containing an excess of N ⁺ Z ⁻ is shaken with water, and then left to stand to separate into two layers. The excess of N ⁺ Z ⁻ is extracted into the aqueous layer and is removed. The object of the ionic liquid Q ⁺ Z ^- if the melting point higher than room temperature, the extraction prior to the operation of the crude ionic liquid Q ⁺ Z ^- a, N ⁺ Z ^- dissolved in does not dissolve the organic solvent (such as dichloromethane) It is necessary to keep it.
Further, when the ionic liquid Q ⁺ Z ⁻ is water-soluble, the crude ionic liquid Q ⁺ Z ⁻ is diluted with a solvent that does not dissolve N ⁺ Z ⁻ (for example, dichloromethane), and then the undissolved N ⁺ Z ⁻ microcrystals Can be removed by filtration.

<Process D2: Third route>
Step D2 is a step following step C2 in the third route.
The process D2 can be basically performed by the same operation as the process D1, and as the acid used in the neutralization described in the process D1, sulfuric acid, phosphoric acid, a carboxylic acid having two or more hydroxyl groups, or the like may be used.

<Process E: common to the third and fourth routes>
The process E is a process following the process D2 in the third route, and is a process following the process C3 in the fourth route, and the ionic liquid Q ⁺ Z ⁻ as the target product can be obtained.
Step E is a step of obtaining ionic liquid Q ⁺ Z ⁻ from the superhydrophilic intermediate Q ⁺ B ⁻ after step D2 or step C3 by an anion exchange method, and basically performed by the same operation as in step A. it can.
That is, the metathesis extraction method described in the step A is suitable, and the superhydrophilic intermediate Q ⁺ B ⁻ is used in place of the <1> ionic liquid precursor described in the step A, and the step described in the step A <4> A salt M ⁺ Z ⁻ (M ⁺ is an arbitrary metal ion) may be used in place of the high melting point intermediate raw material salt M ⁺ Y ⁻ (see also the following formula (12)).

Water may be used as the solvent, and the target ionic liquid Q ⁺ Z ⁻ is extracted into a phase different from the by-product, and then the ionic liquid Q ⁺ Z ⁻ is removed by removing the solvent from the ionic liquid Q ⁺ Z −. ^- it is possible to obtain.

  EXAMPLES Hereinafter, although the manufacturing method of the ionic liquid concerning this invention and the manufacturing method of the intermediate body for ionic liquid manufacture concerning an invention are demonstrated using an Example, this invention is not limited to these Examples.

[Example 1: Example of first route]
<Process A>
As the high melting point intermediate Q ⁺ Y ⁻ , a phosphonium salt ionic liquid represented by the above general formula (1) and having R ₁ = R ₂ = R ₃ = R ₄ = n-octyl group was synthesized (hereinafter referred to as “high melting point intermediate Q ⁺ Y ^−” ). Cation Q ⁺ in this ionic liquid is abbreviated as [P ₈₈₈₈ ]).
That is, first, based on a known method, trioctylphosphine and bromooctane were directly reacted at 108 ° C. without solvent to synthesize [P ₈₈₈₈ ] [Br].
Next, the obtained [P ₈₈₈₈ ] [Br] was _subjected to anion exchange to [P ₈₈₈₈ ] [BF ₄ ] by a metathesis extraction method.
Specifically, according to the above formula (8), a 1-pentanol solution of [P ₈₈₈₈ ] [Br] and an aqueous NaBF ₄ solution were mixed and stirred. NaBF ₄ was used in a substance amount ratio of 1.2 equivalents with respect to [P ₈₈₈₈ ] [Br].
When the mixture was allowed to stand, it was separated into two layers, an aqueous layer and an organic layer. By separating the organic layer, [P ₈₈₈₈ ] [BF ₄ ] containing a small amount of 1-pentanol was obtained.

<Process B>
[P ₈₈₈₈ ] [BF ₄ ] obtained above was recrystallized 6 times under the following conditions.
Solvent: Methanol Charge concentration: 20% by weight
Cooling temperature: -18 ° C
Saturated solution concentration at cooling temperature: 1.5% by weight
Solvent adsorption amount of solid phase (at the time of recovery): 15% by weight
Yield (per time): 94.2%
After recrystallization, the obtained high-melting-point intermediate was vacuum-dried. FIG. 2 shows the ¹ H-NMR and ¹³ C-NMR spectra of the purified high-melting-point intermediate [P ₈₈₈₈ ] [BF ₄ ]. Impurities were less than the detection limit (0.05%) in ¹ H-NMR and ¹³ C-NMR spectra. Further, the residual Br ⁻ of the precursor was analyzed by the Mohr method, but it was less than the detection limit (0.03%).
Therefore, it was confirmed that the purity of the purified high melting point intermediate [P ₈₈₈₈ ] [BF ₄ ] was 99.9% or more. The melting point was measured and found to be 86 ° C.

<Process C1>
27 g (47 mmol) of [P ₈₈₈₈ ] [BF ₄ ] purified as described above was dissolved in 250 mL of 2-propanol at room temperature. 9.3 g of cesium formate (52 mmol) was dissolved in 55 mL of 2-propanol at room temperature.
When both were mixed at room temperature, precipitation occurred, and suction filtration was performed.
After NMR analysis of the components of the filtrate and confirming that the concentration of Cs ⁺ exceeds the concentration of BF ₄ ⁻ by two times or more, the filtrate was cooled to −40 ° C. in a freezer and newly cooled. In order to remove the precipitate formed in the sample, it was naturally filtered twice. 2-Propanol was distilled off with an evaporator.
A highly viscous liquid was obtained, which was the target product, but precipitation of microcrystals (excess of cesium formate) was observed. Therefore, about 100 g of water was added to this highly viscous liquid and stirred well. When left standing, the target ionic liquid [P ₈₈₈₈ ] [HCOO] and cesium formate aqueous solution were separated, and the latter was removed. At this time, the ionic liquid contained water (containing a water content of 5.9 in molar ratio), but the ionic liquid is more excellent in storage stability in the water-containing state. When water is completely removed, it is easily oxidized by air due to the reductive nature of formate ions, resulting in a decrease in purity. In this water-containing state, 22.6 g (36 mmol, yield 76%) of the target ionic liquid was obtained.
The ¹³ C-NMR spectrum of the resulting ionic liquid [P ₈₈₈₈ ] [HCOO] is shown in FIG. From the spectrum, it was confirmed that the anion could be exchanged for formate ion. On the other hand, in this ionic liquid, BF ₄ ⁻ derived from a high melting point intermediate, Cs ⁺ derived from an anion source, and 2-propanol which is a solvent for metathesis precipitation are expected as impurities. Accordingly, when the presence of these impurities was analyzed, 18 ppm of BF ₄ ⁻ was detected by ¹⁹ F-NMR (substance-based anion exchange rate 99.989%). On the other hand, Cs ⁺ was not detected by ¹³³ Cs-NMR (detection limit 50 ppm). In ¹ H-NMR, 2-propanol was not detected (detection limit 20 ppm). Therefore, it was confirmed that the purity of the obtained ionic liquid [P ₈₈₈₈ ] [HCOO] was 99.9% or more.

[Example 2: Example of first route]
<Process A>
As the high melting point intermediate Q ⁺ Y ⁻ , an ammonium salt ionic liquid represented by the above general formula (2) and having R ₁ = n-octyl group and R ₂ = R ₃ = R ₄ = n-butyl group is used. Synthesized (hereinafter, the cation Q ⁺ in this ionic liquid is abbreviated as [N ₄₄₄₈ ]).
That is, first, tributylamine and octyl iodide were directly reacted at 108 ° C. without solvent in accordance with a known method to synthesize [N ₄₄₄₈ ] [I]. In order to remove unreacted tributylamine, the product was dissolved in three times the amount of methanol, and a methanol solution of sodium hydroxide was added to adjust the pH to around 9. A yellow oily substance (unreacted tributylamine) was separated and removed by liquid separation.
Next, the obtained [N ₄₄₄₈ ] [I] was _subjected to anion exchange to [N ₄₄₄₈ ] [PF ₆ ] by a metathesis extraction method.
Specifically, according to the above formula (8), an aqueous solution of [N ₄₄₄₈ ] [I] and an aqueous KPF ₆ solution were mixed, and dichloromethane was added and stirred. KPF ₆ was used at a substance amount ratio of 1.1 equivalent to [N ₄₄₄₈ ] [I].
When the mixture was allowed to stand, it was separated into two layers, an aqueous layer and an organic layer. The organic layer was separated, and the solvent was distilled off to obtain [N ₄₄₄₈ ] [PF ₆ ].

<Process B>
[N ₄₄₄₈ ] [PF ₆ ] obtained above was recrystallized 7 times under the following conditions.
Solvent: Methanol Charge concentration: 20% by weight
Cooling temperature: -6 ° C
Saturated solution concentration at cooling temperature: 6.4% by weight
Solvent adsorption amount of solid phase (at recovery): 52% by weight
Yield (per time): 78.5%
After recrystallization, the obtained high-melting-point intermediate was vacuum-dried. FIG. 4 shows the ¹ H-NMR and ¹³ C-NMR spectra of the purified high-melting-point intermediate [N ₄₄₄₈ ] [PF ₆ ]. Impurities were less than the detection limit (0.05%) in ¹ H-NMR and ¹³ C-NMR spectra. Further, the residual Br ⁻ of the precursor was analyzed by the Mohr method, but it was less than the detection limit (0.03%).
Therefore, it was confirmed that the purity of the purified high-melting intermediate [N ₄₄₄₈ ] [PF ₆ ] was 99.9% or more. The melting point was measured and found to be 78 ° C.

<Process C1>
28.9 g of 2-propanol solution containing 11.7% by weight (7.76 mmol) of [N ₄₄₄₈ ] [PF ₆ ] purified as described above was prepared. Separately, 3.47 g (8.4 mmol) of Cs [(CF ₃ SO ₂ ) ₂ N] was dissolved in 30 mL of 2-propanol.
When both solutions were mixed, a precipitate was formed, and suction filtration was performed.
The components of the filtrate were NMR analysis, the concentration of Cs ⁺ is PF ₆ ^- After confirming that exceeds the concentration of more than 2 times, the filtrate was cooled to -60 ° C. in a freezer, a new at a cold enough In order to remove the precipitate formed in the sample, it was naturally filtered twice.
2-Propanol was distilled off with an evaporator. Since a small amount of crystallites (excess Cs [(CF ₃ SO ₂ ) ₂ N]) was precipitated, the ionic liquid was once diluted with a small amount of dichloromethane and removed by washing with water. Thereafter, dichloromethane and water were distilled off from the ionic liquid layer to obtain the desired product (0.9 g, yield 20%).
FIG. 5 shows the ¹³ C-NMR and ¹⁹ F-NMR spectra of the resulting ionic liquid [N ₄₄₄₈ ] [(CF ₃ SO ₂ ) ₂ N]. From the spectrum, it was confirmed that the anion could be exchanged with [(CF ₃ SO ₂ ) ₂ N] ion. In this ionic liquid, PF ₆ ⁻ derived from a high-melting-point intermediate, Cs ⁺ derived from an anion source, 2-propanol and dichloromethane as solvents used during the synthesis are expected as impurities. Therefore, analysis of the presence of these impurities, PF ₆ by ¹⁹ F-NMR ^- was not detected (detection limit 10 ppm, substance amount based anion exchange rates 99.999% or higher). On the other hand, 106 ppm of Cs ⁺ was detected by ¹³³ Cs-NMR. ^{In 1} H-NMR, 2-propanol and dichloromethane were not detected (detection limit 20 ppm). Therefore, it was confirmed that the purity of the obtained ionic liquid [N ₄₄₄₈ ] [(CF ₃ SO ₂ ) ₂ N] was 99.9% or more.

[Example 3: Example of first route]
<Process A>
A pyrrolidinium salt ionic liquid represented by the above general formula (3) and having R ₁ = methyl group and R ₂ = n-propyl group was synthesized as the high melting point intermediate Q ⁺ Y ⁻ (hereinafter, this ionic liquid) The cation Q ⁺ in the above is abbreviated as [Pyrr ₁₃ ]).
That is, first, 1-methylpyrrolidine and bromopropane were directly reacted at 60 ° C. without solvent in accordance with a known method to obtain [Pyrr ₁₃ ] [Br].
Next, the obtained [Pyrr ₁₃ ] [Br] was subjected to anion exchange to [Pyrr ₁₃ ] [PF ₆ ] by a metathesis extraction method.
Specifically, according to the above formula (8), an aqueous solution of [Pyrr ₁₃ ] [Br] and an aqueous KPF ₆ solution were mixed, and further dichloromethane was added and stirred. KPF ₆ was used at a substance amount ratio of 1.1 equivalent to [Pyrr ₁₃ ] [Br]. Dichloromethane was used in an amount twice the weight of [Pyrr ₁₃ ] [Br].
When the mixture was allowed to stand, it was separated into two layers, an aqueous layer and an organic layer. Therefore, the organic layer was separated and the solvent was distilled off to obtain [Pyrr ₁₃ ] [PF ₆ ].

<Process B>
[Pyrr ₁₃ ] [PF ₆ ] obtained above was recrystallized three times under the following conditions.
Solvent: Methanol Feeding concentration: 25% by weight
Cooling temperature: -20 ° C
Saturated solution concentration at cooling temperature: 1.6% by weight
Solvent adsorption amount in solid phase (at recovery): 3% by weight
Yield (per time): 95.2%
After recrystallization, the obtained high-melting-point intermediate was vacuum-dried. FIG. 6 shows ¹ H-NMR and ¹³ C-NMR spectra of the purified high-melting-point intermediate [Pyrr ₁₃ ] [PF ₆ ]. Impurities were less than the detection limit (0.05%) in ¹ H-NMR and ¹³ C-NMR spectra. Further, the residual Br ⁻ of the precursor was analyzed by the Mohr method, but it was less than the detection limit (0.03%).
Therefore, it was confirmed that the purity of the purified high melting point intermediate [Pyrr ₁₃ ] [PF ₆ ] was 99.9% or more. The melting point was measured and found to be 112 ° C.

<Process C1>
8.21 g (30.2 mmol) of [Pyrr ₁₃ ] [PF ₆ ] purified by the above was placed in a flask. To this was added 39.53 g of a 2-propanol solution containing 14.9% by weight of CsHCOO (ie containing 33 mmol of cesium formate). [Pyrr ₁₃ ] [PF ₆ ] is poorly soluble in 2-propanol, but when the solution was stirred at room temperature for 2 days, [Pyrr ₁₃ ] [PF ₆ ] was consumed by the reaction and newly precipitated (Cs [PF 6 ₆ ]) occurred. This precipitate was suction filtered. This solution was cooled to −40 ° C. in a freezer, and spontaneously filtered twice in order to remove newly formed precipitates when sufficiently cooled.
2-Propanol was distilled off with an evaporator. When the solvent was distilled off, microcrystals (excess of cesium formate) were precipitated in the ionic liquid. In order to remove the microcrystals, the ionic liquid was diluted with dichloromethane and filtered. The solvent was distilled off from the filtrate to obtain 4.0 g (yield 77%) of the target ionic liquid [Pyrr ₁₃ ] [HCOO].
FIG. 7 shows the ¹³ C-NMR spectrum of the obtained ionic liquid [Pyrr ₁₃ ] [HCOO]. From the spectrum, it was confirmed that the anion could be exchanged for formate ion. In this ionic liquid, PF ₆ ⁻ derived from a high-melting-point intermediate, Cs ⁺ derived from an anion source, 2-propanol and dichloromethane as solvents used during the synthesis are expected as impurities. Therefore, when the presence of these impurities was analyzed, 1100 ppm of PF ₆ ⁻ was detected by ¹⁹ F-NMR (substance-based anion exchange rate 99.87%). Cs ⁺ was detected at 3000 ppm by ¹³³ Cs-NMR. ^{In 1} H-NMR, 2-propanol and dichloromethane were not detected (detection limit 20 ppm). Therefore, it was confirmed that the purity of the obtained ionic liquid [Pyrr ₁₃ ] [HCOO] was 99.6%.

[Example 4: Example of the second route]
<Process A>
As the high melting point intermediate Q ⁺ Y ⁻ , a phosphonium salt-based ionic liquid represented by the above general formula (1) and having R ₁ = n-octyl group and R ₂ = R ₃ = R ₄ = n-butyl group is used. (The cation Q ⁺ in this ionic liquid is hereinafter abbreviated as [P ₄₄₄₈ ]).
That is, first, based on a known method, tributylphosphine and bromooctane were directly reacted at 108 ° C. without solvent to synthesize [P ₄₄₄₈ ] [Br].
Next, the obtained [P ₄₄₄₈ ] [Br] was _subjected to anion exchange to [P ₄₄₄₈ ] [PF ₆ ] by a metathesis extraction method.
Specifically, according to the above formula (8), [P ₄₄₄₈ ] [Br] (liquid) and an aqueous KPF ₆ solution were mixed and stirred. KPF ₆ was used at a substance amount ratio of 1.1 equivalent to [P ₄₄₄₈ ] [Br].
When the mixture was allowed to stand, it was separated into two layers, an aqueous layer and an organic layer. Therefore, the organic layer was separated and the solvent was distilled off to obtain [P ₄₄₄₈ ] [PF ₆ ].

<Process B>
[P ₄₄₄₈ ] [PF ₆ ] obtained above were recrystallized four times under the following conditions.
Solvent: Methanol Charge concentration: 20% by weight
Cooling temperature: −60 ° C. (first 2 times), −38 ° C. (after 2 times)
Saturated solution concentration at cooling temperature: 1.8% by weight (first 2 times), 6.5% by weight (after 2 times)
Solvent adsorption amount of solid phase (at the time of recovery): 35% by weight (first 2 times), 26% by weight (after 2 times)
Yield (per 1 time): 93.6% (first 2 times), 74% (2 times later)
After recrystallization, the obtained high-melting-point intermediate was vacuum-dried. FIG. 8 shows the ¹ H-NMR and ¹³ C-NMR spectra of this purified high-melting intermediate [P ₄₄₄₈ ] [PF ₆ ]. Impurities were less than the detection limit (0.05%) in ¹ H-NMR and ¹³ C-NMR spectra.
Therefore, it was confirmed that the purity of the purified high-melting-point intermediate [P ₄₄₄₈ ] [PF ₆ ] was 99.9% or more. It was 36 degreeC when melting | fusing point was measured.

<Process C2>
31.6 g (68.6 mmol) of [P ₄₄₄₈ ] [PF ₆ ] purified by the above was dissolved in 2-propanol. 25 g of CsOH · H ₂ O (purchased from Nacalai Tesque, 149 mmol) was dissolved in 250 g of 2-propanol. When 134 g of the latter solution was added to the former, a precipitate (Cs [PF ₆ ]) was deposited, and suction filtration was performed.
The components of the filtrate were analyzed by NMR, and after confirming that the concentration of Cs ⁺ exceeded the concentration of PF ₆ ⁻ by 2 times or more, 2-propanol was added to the filtrate to make the total amount 1.0 L. Further, 430 g of hexane was added, then cooled to −80 ° C. in a freezer, and naturally filtered twice in order to remove newly formed precipitates when sufficiently cooled. The filtrate was moderately concentrated by an evaporator to obtain the desired strong base type intermediate [P ₄₄₄₈ ] [OH] as a 2-propanol solution (12% by weight). The yield was 21.7 g (65.3 mmol, yield 95%) as a pure component.
The resulting strongly basic type impurity intermediate solution was NMR analysis, PF ₆ by ¹⁹ F-NMR ^- ions 90 ppm (material amount based anion exchange rate 99.84%), Cs by ¹³³ Cs-NMR ⁺ Was detected at 2740 ppm.

<Process D1>
31.1 g (10.5 mmol) of a 11.2 wt% 2-propanol solution of [P ₄₄₄₈ ] [OH] was neutralized with an aqueous 0.22 mol / L acetic acid solution. The neutralization point was judged with a pH meter. After neutralization, the solvent was distilled off, and then 20 mL of dichloromethane was added. As a result, microcrystals (cesium acetate) were precipitated. The supernatant was collected after waiting for the precipitation to settle. Dichloromethane was distilled off to obtain 3.75 g (10.0 mmol, yield: 95%) of the target ionic liquid [P ₄₄₄₈ ] [CH ₃ COO].
The ¹³ C-NMR spectrum of the resulting ionic liquid [P ₄₄₄₈ ] [CH ₃ COO] is shown in FIG. From the spectrum, it was confirmed that the anion could be exchanged for acetate ion. In this ionic liquid, 580 ppm of Cs ⁺ was detected by ¹³³ Cs-NMR. ^{In 1} H-NMR, 2-propanol and dichloromethane were not detected (detection limit 20 ppm). Therefore, it was confirmed that the purity of the obtained ionic liquid [P ₄₄₄₈ ] [CH ₃ COO] was 99% or more.

[Example 5: Example of third route]
<Process A>
[P ₄₄₄₈ ] [PF ₆ ] were obtained in the same manner as in Step A of Example 4.

<Process B>
[P ₄₄₄₈ ] [PF ₆ ] was recrystallized in the same manner as in Step B of Example 4.

<Process C2>
[P ₄₄₄₈ ] [OH] was obtained in the same manner as in Step C2 of Example 4.

<Process D2>
63.7 g (23.6 mmol) of a 12.3 wt% 2-propanol solution of [P ₄₄₄₈ ] [OH] was neutralized with 0.50 mol / L dilute sulfuric acid. The neutralization point was judged with a pH meter. After neutralization, the solvent was distilled off. As a result of this operation, a precipitate (cesium sulfate) was mixed with the product, and the product was once diluted with 20 mL of ethylene glycol dimethyl ether, and the supernatant was collected after waiting for the precipitate to settle. The solvent was distilled off from the supernatant, and then the target product was diluted with water, whereby 14.1 g (8.85 mmol, yield 75) of a 45.6% by weight aqueous solution of a superhydrophilic intermediate [P ₄₄₄₈ ] ₂ [SO ₄ ] was obtained. %).
FIG. 10 shows the ¹⁷ O-NMR spectrum of the obtained superhydrophilic intermediate. From the spectrum, anion exchange to sulfate ion was confirmed. According to ¹³³ Cs-NMR, 160 ppm of Cs ⁺ was detected in this superhydrophilic intermediate.

<Process E>
0.675 g of sodium methanesulfonate and 5 g of water were added to 3.93 g (2.47 mmol) of a 45.6% by weight aqueous solution of [P ₄₄₄₈ ] ₂ [SO ₄ ] obtained in Step D2. Further, 6 g of dichloromethane was added and stirred. Since it was separated into two layers, the lower layer was collected. The lower layer was further washed twice with an aqueous solution containing 0.07 g of sodium methanesulfonate. After washing the lower layer with water, the solvent was distilled off with an evaporator to obtain 1.59 g (3.87 mmol, yield 78%) of the target ionic liquid ([P ₄₄₄₈ ] [CH ₃ SO ₃ ]).
The ¹³ C-NMR spectrum of the resulting ionic liquid [P ₄₄₄₈ ] [CH ₃ SO ₃ ] is shown in FIG. From the spectrum, it was confirmed that the anion could be exchanged for the methanesulfonate ion. Cs ⁺ was not detected in this ionic liquid by ¹³³ Cs-NMR (detection limit: 20 ppm). In addition, 2-propanol and dichloromethane, which are solvents used during the synthesis, were not detected (detection limit 20 ppm). Therefore, it was confirmed that the purity of the obtained ionic liquid [P ₄₄₄₈ ] [CH ₃ SO ₃ ] was 99% or more.

[Example 6: Example of fourth route]
<Process A>
[P ₄₄₄₈ ] [PF ₆ ] were obtained in the same manner as in Step A of Example 4.

<Process B>
[P ₄₄₄₈ ] [PF ₆ ] was recrystallized in the same manner as in Step B of Example 4.

<Process C3>
6.30 g (13.7 mmol) of [P ₄₄₄₈ ] [PF ₆ ] purified as described above was dissolved in 30 g of ethanol at room temperature. 1.99 g of tetramethylammonium sulfate (purchased from Tokyo Chemical Industry, 8.15 mmol) was dissolved in 20 g of ethanol at room temperature.
When both were mixed at room temperature, a precipitate was formed, which was suction filtered, and 10 g of ethanol was added to the filtrate.
The components of the filtrate were subjected to NMR analysis, and after confirming that the concentration of tetramethylammonium ions was more than twice the concentration of PF ₆ ⁻ , the filtrate was cooled to −53 ° C. in a freezer and cooled sufficiently. By the way, natural filtration was performed twice in order to remove newly generated precipitate. Ethanol was distilled off with an evaporator.
A highly viscous liquid was obtained, which was the target product, but precipitation of microcrystals (tetramethylammonium sulfate) was observed. Therefore, this highly viscous liquid was diluted with about 20 g of benzene, and insoluble matter was filtered. Benzene was distilled off from the filtrate with an evaporator.
The obtained highly viscous liquid was appropriately diluted with water to obtain 10.1 g (3.86 mmol, yield 56%) of a 27.7 wt% aqueous solution of the superhydrophilic intermediate [P ₄₄₄₈ ] ₂ [SO ₄ ]. Obtained.
FIG. 12 shows the ¹⁷ O-NMR spectrum of the obtained superhydrophilic intermediate. From the spectrum, anion exchange to sulfate ion was confirmed. On the other hand, in this ionic liquid, PF ₆ ⁻ derived from a high melting point intermediate and tetramethylammonium ion derived from an anion source are expected as impurities. Therefore, analysis of the presence of these impurities, PF ₆ by ¹⁹ F-NMR ^- is 35 ppm (anion exchange rate in material weight basis 99.968%) were detected. On the other hand, 23 ppm of tetramethylammonium ion was detected by ¹ H-NMR. Therefore, it was confirmed that the purity of the obtained superhydrophilic intermediate [P ₄₄₄₈ ] ₂ [SO ₄ ] was 99.9% or more (excluding the solvent).

<Process E>
[P ₄₄₄₈ ] [CH ₃ SO ₃ ] was obtained in the same manner as in Step E of Example 5.

[Reference example]
In order to clarify that the present invention can be widely applied in addition to the above embodiments, some reference examples will be described below.
Reference Examples 1 to 11 relate to operations up to Step B shown in FIG.
In the present invention, in particular, since a process from obtaining a high-melting-point intermediate to recrystallization is one of the important features, those skilled in the art will consider the other descriptions in the present specification and perform the following reference examples. It is possible to obtain the target ionic liquid and intermediate through steps C1 and the like while performing the operations up to step B based on the description of 1 to 11. Therefore, the following Reference Examples 1 to 11 are substantially This can be equated with the embodiment of the present invention.
The recrystallization conditions in step B and the melting point in the dry state of the recrystallized high melting point intermediate are summarized in Table 3 below. For convenience of reference, the recrystallization conditions in Step B of Examples 1 to 6 are also shown in Table 3.

<Reference Example 1: Phosphonium salt ionic liquid>
A phosphonium salt ionic liquid represented by the above general formula (1) and having R ₁ = methyl group and R ₂ = R ₃ = R ₄ = n-butyl group was synthesized as the high melting point intermediate Q ⁺ Y ⁻ . (Hereinafter, the cation Q ⁺ in this ionic liquid is abbreviated as [P ₄₄₄₁ ]).
That is, first, based on a known method, tributylphosphine and iodomethane were reacted in hexane at room temperature to synthesize [P ₄₄₄₁ ] [I]. At this time, [P ₄₄₄₁ ] [I] was separated from the solvent by suction filtration.
Next, the obtained [P ₄₄₄₁ ] [I] was _subjected to anion exchange to [P ₄₄₄₁ ] [BF ₄ ] by a _metathetical extraction method.
Specifically, according to the above formula (8), a dichloromethane solution of [P ₄₄₄₁ ] [I] and an aqueous NaBF ₄ solution were mixed and stirred. NaBF ₄ was used in a substance amount ratio of 2.0 equivalents to [P ₄₄₄₁ ] [I].
When the mixture was allowed to stand, it was separated into two layers, an aqueous layer and an organic layer. Therefore, the organic layer was separated and the solvent was distilled off to obtain [P ₄₄₄₁ ] [BF ₄ ].
The obtained [P ₄₄₄₁ ] [BF ₄ ] was recrystallized 10 times under the conditions shown in Table 3.

<Reference Example 2: Phosphonium salt ionic liquid>
As the high melting point intermediate Q ⁺ Y ⁻ , a phosphonium salt ionic liquid represented by the above general formula (1) and having R ₁ = n-propyl group and R ₂ = R ₃ = R ₄ = n-butyl group is used. Synthesized (hereinafter, the cation Q ⁺ in this ionic liquid is abbreviated as [P ₄₄₄₃ ]).
That is, first, based on a known method, tributylphosphine and bromopropane were directly reacted at 70 ° C. without solvent to synthesize [P ₄₄₄₃ ] [Br].
Next, the obtained [P ₄₄₄₃ ] [Br] was _subjected to anion exchange to [P ₄₄₄₃ ] [BF ₄ ] by a metathesis extraction method.
Specifically, according to the above formula (8), a dichloromethane solution of [P ₄₄₄₃ ] [Br] and an aqueous NaBF ₄ solution were mixed and stirred. NaBF ₄ was used in a substance amount ratio of 1.3 equivalent to [P ₄₄₄₃ ] [Br].
When the mixture was allowed to stand, it was separated into two layers, an aqueous layer and an organic layer, and thus the organic layer was separated and the solvent was distilled off to obtain [P ₄₄₄₃ ] [BF ₄ ].
The obtained [P ₄₄₄₃ ] [BF ₄ ] was recrystallized 6 times under the conditions shown in Table 3.

<Reference Example 3: Phosphonium salt ionic liquid>
As the high melting point intermediate Q ⁺ Y ⁻ , a phosphonium salt ionic liquid represented by the above general formula (1) and having R ₁ = R ₂ = R ₃ = R ₄ = n-butyl group was synthesized (hereinafter referred to as “high melting point intermediate Q ⁺ Y ^−” ). Cation Q ⁺ in this ionic liquid is abbreviated as [P ₄₄₄₄ ]).
That is, [P ₄₄₄₄ ] [Br] (purchased from Tokyo Kasei) was anion-exchanged to [P ₄₄₄₄ ] [BF ₄ ] by the metathesis extraction method.
Specifically, according to the above formula (8), an aqueous solution of [P ₄₄₄₄ ] [Br] and an aqueous NaBF ₄ solution were mixed, and 1-pentanol was further added and stirred. NaBF ₄ was used at a substance amount ratio of 1.3 equivalent to [P ₄₄₄₄ ] [Br]. 1-Pentanol was used at 25% by weight with respect to [P ₄₄₄₄ ] [Br].
The obtained [P ₄₄₄₄ ] [BF ₄ ] was recrystallized 6 times under the conditions shown in Table 3.

<Reference Example 4: Phosphonium salt ionic liquid>
As the high melting point intermediate Q ⁺ Y ⁻ , a phosphonium salt-based ionic liquid represented by the above general formula (1) and having R ₁ = n-octyl group and R ₂ = R ₃ = R ₄ = n-butyl group is used. (The cation Q ⁺ in this ionic liquid is hereinafter abbreviated as [P ₄₄₄₈ ]).
That is, first, based on a known method, tributylphosphine and bromooctane were directly reacted at 108 ° C. without solvent to synthesize [P ₄₄₄₈ ] [Br].
Next, the obtained [P ₄₄₄₈ ] [Br] was _subjected to anion exchange to [P ₄₄₄₈ ] [BF ₄ ] by a metathesis extraction method.
Specifically, according to the above formula (8), [P ₄₄₄₈ ] [Br] (liquid) and an aqueous NaBF ₄ solution were mixed and stirred. NaBF ₄ was used at a substance amount ratio of 1.2 equivalent to [P ₄₄₄₈ ] [Br].
When the mixture was allowed to stand, it was separated into two layers, an aqueous layer and an organic layer. The organic layer was separated to obtain [P ₄₄₄₈ ] [BF ₄ ] (liquid at room temperature).
The obtained [P ₄₄₄₈ ] [BF ₄ ] was recrystallized twice under the conditions shown in Table 3.

[Reference Example 5: Ammonium salt ionic liquid]
An ammonium salt ionic liquid represented by the above general formula (2) and having R ₁ = ethyl group and R ₂ = R ₃ = R ₄ = n-butyl group was synthesized as the high melting point intermediate Q ⁺ Y ⁻ . (Hereinafter, the cation Q ⁺ in this ionic liquid is abbreviated as [N ₄₄₄₂ ]).
That is, first, [N ₄₄₄₂ ] [Br] was synthesized by a solvent-free direct reaction of tributylamine and bromoethane based on a known method.
Next, [N ₄₄₄₂ ] [Br] was _subjected to anion exchange to [N ₄₄₄₂ ] [BF ₄ ] by a metathesis extraction method.
Specifically, according to the above formula (8), an aqueous solution of [N ₄₄₄₂ ] [Br] and an aqueous NaBF ₄ solution were mixed and stirred. NaBF ₄ was used at a substance amount ratio of 1.5 equivalents to [N ₄₄₄₂ ] [Br].
When the mixture was allowed to stand, it was separated into two layers, an aqueous layer and an organic layer. The organic layer was separated and the solvent was distilled off to obtain [N ₄₄₄₂ ] [BF ₄ ].
The obtained [N ₄₄₄₂ ] [BF ₄ ] was recrystallized 6 times under the conditions shown in Table 3.

[Reference Example 6: Ammonium salt ionic liquid]
As the high melting point intermediate Q ⁺ Y ⁻ , an ammonium salt ionic liquid represented by the above general formula (2) and having R ₁ = R ₂ = R ₃ = R ₄ = n-butyl group was synthesized (hereinafter referred to as “high melting point intermediate Q ⁺ Y ^−” ). Cation Q ⁺ in this ionic liquid is abbreviated as [N ₄₄₄₄ ]).
That is, [N ₄₄₄₄ ] [Br] purchased from Tokyo Kasei was anion-exchanged to [N ₄₄₄₄ ] [BF ₄ ] by the metathesis extraction method.
Specifically, according to the above formula (8), an aqueous solution of [N ₄₄₄₄ ] [Br] and an aqueous NaBF ₄ solution were mixed, and further dichloromethane was added and stirred. NaBF ₄ was used in a substance amount ratio of 1.5 equivalents to [N ₄₄₄₄ ] [Br]. Dichloromethane was used in an amount of 1 time by weight with respect to [N ₄₄₄₄ ] [Br].
When the mixture was allowed to stand, it was separated into two layers, an aqueous layer and an organic layer, and thus the organic layer was separated and the solvent was distilled off to obtain [N ₄₄₄₄ ] [BF ₄ ].
The obtained [N ₄₄₄₄ ] [BF ₄ ] was recrystallized three times under the conditions shown in Table 3.

[Reference Example 7: Ammonium salt ionic liquid]
As the high melting point intermediate Q ⁺ Y ⁻ , an ammonium salt ionic liquid represented by the above general formula (2) and having R ₁ = R ₂ = R ₃ = R ₄ = n-pentyl group was synthesized (hereinafter referred to as “high melting point intermediate Q ⁺ Y ^−” ). Cation Q ⁺ in this ionic liquid is abbreviated as [N ₅₅₅₅ ]).
That is, [N ₅₅₅₅ ] [Br] purchased from Tokyo Kasei was _subjected to anion exchange to [N ₅₅₅₅ ] [BF ₄ ] by the metathesis extraction method.
Specifically, according to the above formula (8), an aqueous solution of [N ₅₅₅₅ ] [Br] and an aqueous NaBF ₄ solution were mixed, and 1-pentanol was further added and stirred. NaBF ₄ was used in a substance amount ratio of 1.5 equivalents to [N ₅₅₅₅ ] [Br]. 1-Pentanol was used in an amount twice as much as that of [N ₅₅₅₅ ] [Br].
When the mixture was allowed to stand, it was separated into two layers, an aqueous layer and an organic layer. The organic layer was separated to obtain [N ₅₅₅₅ ] [BF ₄ ] containing 1-pentanol.
The obtained [N ₅₅₅₅ ] [BF ₄ ] was recrystallized three times under the conditions shown in Table 3.

[Reference Example 8: Ammonium salt ionic liquid]
As the high melting point intermediate Q ⁺ Y ⁻ , an ammonium salt ionic liquid represented by the above general formula (2) and having R ₁ = R ₂ = R ₃ = R ₄ = n-octyl group was synthesized (hereinafter referred to as “high melting point intermediate Q ⁺ Y ^−” ). Cation Q ⁺ in this ionic liquid is abbreviated as [N ₈₈₈₈ ]).
That is, first, trioctylamine and octyl iodide were directly reacted at 108 ° C. without solvent in accordance with a known method to synthesize [N ₈₈₈₈ ] [I]. In order to remove unreacted trioctylamine, the product was dissolved in 3 times the amount of methanol, and a methanol solution of sodium hydroxide was added to adjust the pH to around 9. A yellow oily substance (unreacted trioctylamine) separated and was removed by liquid separation.
Next, the obtained [N ₈₈₈₈ ] [I] was _subjected to anion exchange to [N ₈₈₈₈ ] [BF ₄ ] by a metathesis extraction method.
Specifically, according to the above formula (8), a dichloromethane solution of [N ₈₈₈₈ ] [I] and an aqueous NaBF ₄ solution were mixed and stirred. NaBF ₄ was used in a substance amount ratio of 1.3 equivalent to [N ₈₈₈₈ ] [I].
When the mixture was allowed to stand, it was separated into two layers, an aqueous layer and an organic layer. Thus, the organic layer was separated and the solvent was distilled off to obtain [N ₈₈₈₈ ] [BF ₄ ].
The obtained [N ₈₈₈₈ ] [BF ₄ ] was recrystallized six times from methanol under the conditions shown in Table 3.

[Reference Example 9: Imidazolium salt ionic liquid]
An imidazolium salt represented by the above general formula (5) as the high melting point intermediate Q ⁺ Y ⁻ , wherein R ₁ = methyl group, R ₂ = n-decyl group, X ₁ = X ₂ = X ₃ = proton A ionic liquid was synthesized (hereinafter, the cation Q ⁺ in this ionic liquid is abbreviated as [C ₁₀ C ₁ Im]).
That is, [C ₁₀ C ₁ Im] [Cl] purchased from Iolitec was anion-exchanged to [C ₁₀ C ₁ Im] [BF ₄ ] by the metathesis extraction method.
Specifically, according to the above formula (8), an aqueous solution of [C ₁₀ C ₁ Im] [Cl] and an aqueous NaBF ₄ solution were mixed and stirred. NaBF ₄ was used in a substance amount ratio of 1.2 equivalents with respect to [C ₁₀ C ₁ Im] [Cl].
When the mixture was allowed to stand, it was separated into two layers, an aqueous layer and an organic layer. The organic layer was separated to obtain [C ₁₀ C ₁ Im] [BF ₄ ] (liquid at room temperature).
The obtained [C ₁₀ C ₁ Im] [BF ₄ ] was recrystallized four times from 2-propanol and then three times from methanol under the conditions shown in Table 3.

[Reference Example 10: Imidazolium salt ionic liquid]
An imidazolium salt represented by the above general formula (5) as the high melting point intermediate Q ⁺ Y ⁻ , wherein R ₁ = R ₂ = n-propyl group, X ₁ = methyl group, X ₂ = X ₃ = proton A ionic liquid was synthesized (hereinafter, cation Q ⁺ in this ionic liquid is abbreviated as [C ₃ C ₃ mIm]).
That is, first, 2-methylimidazole was used as a starting material, and a known method (with 1-propyl-2 by reacting with 1 equivalent of bromopropane at room temperature after carrying out proton extraction with sodium hydride using monoglyme as a solvent). -After obtaining methylimidazole, this was further reacted with 1 equivalent of bromopropane in 2-propanol at 60 ° C to synthesize [C ₃ C ₃ mIm] [Br].
Next, the obtained [C ₃ C ₃ mIm] [Br] was subjected to anion exchange to [C ₃ C ₃ mIm] [BF ₄ ] by a metathesis extraction method.
Specifically, according to the above formula (8), an aqueous solution of [C ₃ C ₃ mIm] [Br] and an aqueous NaBF ₄ solution were mixed, and further dichloromethane was added and stirred. NaBF ₄ was used at a substance amount ratio of 2.0 equivalents with respect to [C ₃ C ₃ mIm] [Br]. Dichloromethane was used in an amount twice the weight of [C ₃ C ₃ mIm] [Br].
When the mixture was allowed to stand, it was separated into two layers, an aqueous layer and an organic layer, and thus the organic layer was separated and the solvent was distilled off to obtain [C ₃ C ₃ mIm] [BF ₄ ].
The obtained [C ₃ C ₃ mIm] [BF ₄ ] was recrystallized three times under the conditions shown in Table 3.

[Reference Example 11: Pyrrolidinium salt-based ionic liquid]
As the high melting point intermediate Q ⁺ Y ⁻ , a pyrrolidinium salt ionic liquid represented by the above general formula (3) and having R ₁ = methyl group and R ₂ = n-octyl group was synthesized (hereinafter, this ionic liquid). The cation Q ⁺ in the above is abbreviated as [Pyrr ₁₈ ]).
That is, first, 1-methylpyrrolidine and bromooctane were directly reacted at 60 ° C. without solvent in accordance with a known method to obtain [Pyrr ₁₈ ] [Br].
Next, the obtained [Pyrr ₁₈ ] [Br] was subjected to anion exchange to [Pyrr ₁₈ ] [BF ₄ ] by a metathesis extraction method.
Specifically, according to the above formula (8), an aqueous solution of [Pyrr ₁₈ ] [Br] and an aqueous NaBF ₄ solution were mixed and stirred. NaBF ₄ was used in a substance amount ratio of 1.8 equivalents with respect to [Pyrr ₁₈ ] [Br].
When the mixture was allowed to stand, it was separated into two layers, an aqueous layer and an organic layer. Therefore, the organic layer was separated and the solvent was distilled off to obtain [Pyrr ₁₈ ] [BF ₄ ] (water absorption at room temperature. Liquid).
The obtained [Pyrr ₁₈ ] [BF ₄ ] was recrystallized three times under the conditions shown in Table 3.

  The method for producing an ionic liquid and the method for producing an intermediate for producing an ionic liquid according to the present invention can be suitably used for producing a high-purity ionic liquid. It can be applied to all the uses that have been expected, and since it is a particularly high-purity ionic liquid, it is expected to contribute to the expansion of the range of use of the ionic liquid more than before.

Claims (11)

A method for producing a desired ionic liquid Q ⁺ Z ⁻ comprising a cation Q ⁺ and an anion Z ⁻ , comprising:
Refining a high melting point intermediate Q ⁺ Y ⁻ comprising a cation Q ⁺ and an anion Y ⁻ and having a recrystallization melting point by recrystallization;
And obtaining the ionic liquid Q ⁺ Z ⁻ directly or indirectly from the purified high melting point intermediate Q ⁺ Y ⁻ . After was organic synthesis, the ionic liquid precursor Q ⁺ X ^{- -} cation Q ⁺ and the anion X ^- of an ion liquid precursor Q ⁺ X including the step of obtaining ^- from the anion-exchange method of a refractory intermediate Q ⁺ Y The manufacturing method of the ionic liquid of Claim 1.   The method for producing an ionic liquid according to claim 2, wherein the anion exchange method is a metathesis extraction method. The method for producing an ionic liquid according to any one of claims 1 to 3, wherein the anion Y ^- is borofluoride ion, hexafluorophosphate ion or tetraphenylborate ion. The method for producing an ionic liquid according to any one of claims 1 to 4, wherein the ionic liquid Q ⁺ Z ^- is obtained from the purified high melting point intermediate Q ⁺ Y ^- by metathesis precipitation. A strong base intermediate Q ⁺ A ⁻ is obtained from the purified high melting point intermediate Q ⁺ Y ⁻ by metathesis precipitation, and an ionic liquid Q ⁺ Z is obtained from the strong base intermediate Q ⁺ A ⁻ by a neutralization method. ^The method for producing an ionic liquid according to any one of claims 1 to 4, wherein-is obtained. A strongly basic intermediate Q ⁺ A ⁻ is obtained from the purified high melting point intermediate Q ⁺ Y ⁻ by metathesis precipitation, and a superhydrophilic intermediate is obtained from the strong base intermediate Q ⁺ A ⁻ by a neutralization method. The method for producing an ionic liquid according to any one of claims 1 to 4, wherein Q ⁺ B ^- is obtained and the ionic liquid Q ⁺ Z ^- is obtained from the superhydrophilic intermediate Q ⁺ B ^- by a metathetical extraction method. A superhydrophilic intermediate Q ⁺ B ⁻ is obtained from the purified high melting point intermediate Q ⁺ Y ⁻ by metathesis precipitation, and an ionic liquid Q ⁺ Z is obtained from the superhydrophilic intermediate Q ⁺ B ⁻ by metathesis extraction. ^The method for producing an ionic liquid according to any one of claims 1 to 4, wherein-is obtained. A method for synthesizing an intermediate for synthesizing a desired ionic liquid Q ⁺ Z ⁻ comprising a cation Q ⁺ and an anion Z ⁻ , comprising:
Refining a high melting point intermediate Q ⁺ Y ⁻ comprising a cation Q ⁺ and an anion Y ⁻ and having a recrystallization melting point by recrystallization;
And a step of obtaining a strongly basic intermediate Q ⁺ A ⁻ from the high-melting intermediate Q ⁺ Y ⁻ after purification by a metathesis precipitation method. A method for synthesizing an intermediate for synthesizing a desired ionic liquid Q ⁺ Z ⁻ comprising a cation Q ⁺ and an anion Z ⁻ , comprising:
Refining a high melting point intermediate Q ⁺ Y ⁻ comprising a cation Q ⁺ and an anion Y ⁻ and having a recrystallization melting point by recrystallization;
Obtaining a strongly basic intermediate Q ⁺ A ⁻ by metathesis precipitation from the purified high melting point intermediate Q ⁺ Y ⁻ ;
The strong base-type intermediate Q ⁺ A ^- superhydrophilic type Intermediate Q ⁺ B by neutralization from ^- and a step of obtaining a method for producing a super-hydrophilic-type intermediates of ionic liquids. A method for synthesizing an intermediate for synthesizing a desired ionic liquid Q ⁺ Z ⁻ comprising a cation Q ⁺ and an anion Z ⁻ , comprising:
Refining a high melting point intermediate Q ⁺ Y ⁻ comprising a cation Q ⁺ and an anion Y ⁻ and having a recrystallization melting point by recrystallization;
And a step of obtaining a superhydrophilic intermediate Q ⁺ B ⁻ from the purified high melting point intermediate Q ⁺ Y ⁻ by metathesis precipitation.

Images