JP5588699B2 - Method for producing ionic liquid - Google Patents

Description

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

  Ionic liquid, also called room temperature molten salt, is a general term for molten salts with a melting point of about 100 ° C. or less. However, due to its extremely low vapor pressure, it has recently attracted attention as a lubricating oil and as a synthetic solvent that can be used repeatedly in high-temperature reactions. (Non-Patent Document 1).

  The ionic liquid is composed of a cation moiety and an anion moiety. As typical cations, dialkylimidazolium, alkylpyridinium, tetraalkylammonium, cyclic pyrrolidinium, and the like are known. On the other hand, many anions such as halides such as chloride, bromide and iodide, and fluorine-containing anions such as tetrafluboroborate, tetrafluorophosphate, trifluoromethanesulfonic acid and bistrifluoromethanesulfonylimide have been reported. Patent Document 2).

  As a method for synthesizing a water-soluble ionic liquid, a method is generally used in which a reaction represented by the following reaction formula (A) is performed, followed by a reaction represented by the following reaction formula (B) (Non-patent Document 3). .

（ここで、Ｒは陰イオン交換樹脂を示し、Ｒ^＋ＯＨ⁻はＯＨ型の陰イオン交換樹脂を示し、Ｘ⁻はハロゲンイオン等のアニオンを示し、Ａはイオン液体のカチオン部位を示し、Ｂはイオン液体のアニオン部位を示す。）

(Where R represents an anion exchange resin, R ⁺ OH ⁻ represents an OH type anion exchange resin, X ⁻ represents an anion such as a halogen ion, A represents a cation portion of an ionic liquid, and B Indicates an anion portion of the ionic liquid.)

J.S.Wilkes, Green Chemistry, 4, 73 (2002) Hiroyuki Ohno, Ionic Liquid II, 2006, P16-22 Hiroyuki Ohno et al, J. Am. Chem. Soc. 2005, 127, 2398-2399.

  However, this method has the following problems.

1. The number of reaction steps is large and the yield is poor.
2. Isolation is difficult because the hydroxide intermediate (A ⁺ OH ⁻ ) at the cation site obtained by the formula (A) is unstable.
3. In order to increase the reactivity of the reaction represented by the formula (B), it is necessary to concentrate water in the aqueous solution of the hydroxide intermediate (A ⁺ OH ⁻ ) at the cation site obtained by the formula (A). Decomposes if concentrated too much because the body is unstable.
3. There are two steps of concentrating the solvent water, which is energy intensive.
4). Purification is difficult because of the degradation product of the hydroxide intermediate.
5. Since the reactivity of Formula (B) is poor, the reaction time is long (12 hours).
6). Since the reaction of the formula (B) needs to be performed while cooling, energy (cold heat) is applied.

Furthermore, when the present inventors use a tetraalkylphosphonium salt or a tetraalkylammonium salt whose counter anion is a halogen ion as the A ⁺ X ⁻ , odorous components such as trialkylphosphine and trialkylamine are present We have found that there is a problem that can occur.

  Then, this invention aims at providing the manufacturing method of the ionic liquid which can eliminate said problem.

  The present invention provides a first step in which an organic acid aqueous solution is brought into contact with an OH-type anion exchange resin, and an anion exchange resin in which an organic acid anion obtained in the first step is supported by the following formula (1): A method for producing an ionic liquid, comprising: a second step of contacting an aqueous solution containing a salt represented; and a third step of deodorizing the ionic liquid obtained in the second step, represented by formula (1): This is an ionic liquid production method using 10 mole equivalents or more of an OH type anion exchange resin and 20 mole equivalents or more of an organic acid with respect to a salt.

［式（１）中、Ｚはリン原子又は窒素原子を示し、Ｒ^１〜Ｒ^４はそれぞれ独立に炭素数１〜１２の環状、直鎖又は分岐状のアルキル基を示し、Ｘはハロゲン原子を示す。］

[In the formula (1), Z represents a phosphorus atom or a nitrogen atom, R ^{1 to} R ⁴ each independently represents a cyclic, linear or branched alkyl group having 1 to 12 carbon atoms, and X represents a halogen atom. Show. ]

Here, in the first step, as shown in the following reaction formula (C), the hydroxide ion in the OH-type anion exchange resin is replaced by an organic acid anion, whereby the following general formula (2) An anion exchange resin carrying the organic acid anion represented is obtained.
In the second step, as shown in the following reaction formula (D), the organic acid anion in the anion exchange resin represented by the general formula (2) is substituted with a halogen ion, whereby the following general formula (3) The ionic liquid which consists of a salt represented by this is obtained.
In the third step, odor components such as trialkylphosphine and trialkylamine, which are impurities contained in the raw material (1), are removed.

（ここで、上記Ｒ^＋は陰イオン交換樹脂を、Ｒ^＋ＯＨ⁻はＯＨ型の陰イオン交換樹脂を、Ｂ’−Ｈは有機酸を、Ｂ’⁻は有機酸アニオンを示す。なお、Ｚ、Ｒ^１〜Ｒ^４、Ｘは、それぞれ上記式（１）におけるものと同義である。）

Here, R ⁺ represents an anion exchange resin, R ⁺ OH ⁻ represents an OH type anion exchange resin, B′—H represents an organic acid, and B ′ ⁻ represents an organic acid anion. , R ^{1 to} R ⁴ and X have the same meanings as those in the above formula (1).)

  According to the production method of the present invention, an ionic liquid can be easily produced at a high yield, and the generated odor component can be efficiently removed.

  In the said manufacturing method, it is preferable that the deodorizing in a 3rd process is performed by the method of contacting the porous which has organic substance adsorption ability, and / or the method of heating in a gas stream.

  In the said manufacturing method, it is preferable that an organic acid is a sulfonic acid or an amino acid.

  The present invention provides a method for easily producing an ionic liquid in a high yield while efficiently removing odor components contained in a raw material. According to the present invention, a useful ionic liquid can be obtained in a short time, in a high yield and without applying energy, which is very preferable from the viewpoint of environmental protection.

  In addition, since the ionic liquid produced by the production method of the present invention is hydrophilic and has excellent heat resistance, a gaseous carrier, an aqueous lubricating oil such as an aqueous cutting oil or an aqueous hydraulic oil, or a synthetic solvent that can be used repeatedly. Etc. can be suitably used.

6 is a diagram showing a GC-MS analysis result of a headspace gas of tetraethylphosphonium taurine salt obtained before the third step of Example 1. FIG. It is a figure which shows the result of the mass spectrometry about the peak of 6.6 minutes in the GC-MS analysis of the head space gas of the tetraethylphosphonium taurine salt obtained before the 3rd process of Example 1. FIG. 3 is a diagram showing a GC-MS analysis result of a headspace gas of tetraethylphosphonium taurine salt obtained through the third step of Example 1. FIG. 2 is a diagram showing a ¹ H-NMR analysis result of a tetraethylphosphonium taurine salt obtained through the third step of Example 1. FIG. 4 is a diagram showing a ¹ H-NMR analysis result of a tetramethylphosphonium taurine salt obtained through the third step of Example 3. FIG.

  Hereinafter, one embodiment of the present invention will be described in detail, but the present invention is not limited to the following embodiment.

  As the OH type anion exchange resin, a general one can be applied. Specific examples thereof include styrene-divinylbenzene copolymer, silica gel, methacrylic acid ester copolymer particles represented by particles obtained by hydrolyzing glycidyl groups of glycidyl methacrylate and ethylene glycol dimethacrylate copolymer particles, and the like. Although what is made into a precursor is mentioned, a styrene divinylbenzene copolymer is generally used from the ease of acquisition.

The ion exchange group in the OH-type anion exchange resin may be any ion exchange group as long as it can exchange anions. The production method is generally a quaternary ammonium method by reacting a tertiary amine in an aqueous suspension copolymerization method.
At this time, it is preferable that the amount of ion exchange groups is functionalized so as to be 0.01 meq / g to 5.5 meq / g in the ion exchange resin.

  Specific products of the OH type anion exchange resin include, for example, Diaion SA10AOH, SANUP manufactured by Mitsubishi Chemical Corporation. Further, an OH form can be obtained by treating an ion exchange resin commercially available as a halogen form such as a chloride with an aqueous NaOH solution, which can be used.

  The organic acid is not particularly limited as long as it dissolves in water to form an aqueous solution. For example, carboxylic acid, sulfonic acid, amino acid and the like can be used, and sulfonic acid and amino acid can be used from the viewpoint of improving heat resistance of the ionic liquid. Are preferred, and aminosulfonic acid and amino acid are more preferred.

  Examples of the sulfonic acid include aminosulfonic acids such as aminomethanesulfonic acid, 2-aminoethanesulfonic acid (taurine), and 3-aminopropanesulfonic acid.

  Examples of amino acids include glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, methionine, asparagine, glutamic acid, glutamine, arginine, lysine, histidine, phenylalanine, tyrosine, tryptophan, aspartic acid, proline, 2-amino. Examples include butyric acid, 2-aminoisobutyric acid, and 2-aminocyclopentanecarboxylic acid.

In the above formula (1), R ^{1 to} R ⁴ are a cyclic, linear or branched alkyl group having 1 to 12 carbon atoms, and a linear or branched alkyl group having 1 to 6 carbon atoms. preferable. The linear or branched alkyl group preferably has 1 to 4 carbon atoms, and more preferably 1 or 2 carbon atoms.

  Examples of the cyclic, linear or branched alkyl group having 1 to 12 carbon atoms include, for example, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, s-butyl group, t-butyl group, and pentyl group. Hexyl group, octyl group, dodecyl group and cyclohexyl group, preferably methyl group, ethyl group, propyl group, isopropyl group and n-butyl group, more preferably methyl group and ethyl group.

  As a halogen atom in said X, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned, for example, Preferably it is a bromine atom.

  Specific examples of the salt represented by the above formula (1) in which Z is a phosphorus atom include tetramethylphosphonium bromide, tetraethylphosphonium bromide, tetrabutylphosphonium bromide, octyltriethylphosphonium bromide, dodecyltrimethylphosphonium bromide, tri Octylethylphosphonium bromide; chlorides corresponding to these bromides can be mentioned, and tetramethylphosphonium bromide, tetraethylphosphonium bromide, and tetrabutylphosphonium bromide are preferred.

  Specific examples of the salt represented by the above formula (1) in which Z is a nitrogen atom include tetramethylammonium bromide, tetraethylammonium bromide, tetrabutylammonium bromide, octyltriethylammonium bromide, dodecyltrimethylammonium bromide, tri Examples include octylethylammonium bromide; chlorides corresponding to these bromides.

  The method of bringing the organic acid aqueous solution into contact with the OH-type anion exchange resin in the first step may be either a batch method or a fluid method.

  In the case of a batch method, the anion exchange resin and the organic acid aqueous solution may be mixed as they are. In the case of performing the flow method, for example, an anion exchange resin can be introduced into the column as it is, and an organic acid aqueous solution can be introduced. This may be introduced into the column after batch ion exchange.

  After the organic acid aqueous solution is brought into contact with the OH type anion exchange resin, it is desirable to wash with pure water or the like in order to remove impurities.

  The method in which the aqueous solution containing the salt represented by the above formula (1) is brought into contact with the anion exchange resin carrying the organic acid anion in the second step may be either a batch type or a fluid type method. Good.

  In the case of performing the batch process, the ionic liquid can be obtained by separating the liquid after contact and the ion exchange resin and then removing the solvent from the liquid. Moreover, when it carries out by a flow type, an ionic liquid can be obtained by collect | recovering effluents and removing a solvent from the collect | recovered effluents. In addition, when organic acid remains in the liquid after contact or the collect | recovered effluent, this may be deposited by adding an appropriate solvent or cooling, and you may remove by filtration.

  Examples of the deodorizing method in the third step include a method of bringing a porous material having an organic substance adsorbing ability into contact and a method of heating in a gas stream.

  A porous material having an organic substance adsorption capacity is a porous material in which, for example, the pore portion is hydrophobic and the organic material is adsorbed in the pore portion. Specific examples thereof include porous ceramics such as activated carbon, zeolite, and alumina.

  Examples of a method for bringing an ionic liquid into contact with a porous material having an organic substance adsorption ability include a method in which a porous material is mixed with an ionic liquid in the form of a stock solution or an aqueous solution and then stirred.

  The gas in the method of heating under a gas stream may be any gas inert to the ionic liquid, and examples thereof include nitrogen, argon, and air.

  The heating temperature and heating time in the method of heating in a gas stream can be adjusted as appropriate depending on the type and amount of the odor component to be generated, but for example, 50 to 250 ° C., 1 to 20 hours, more preferably 150 to The temperature can be 220 ° C. and 3 to 15 hours.

  Even when any of the above-described deodorizing methods is used, it is desirable to deodorize until no odor component is detected in the headspace gas analysis by the GC-MS analysis and the human being cannot actually sense the odor.

  The OH type anion exchange resin is used in an amount of 10 molar equivalents or more, preferably 20 molar equivalents or more based on the salt represented by the above formula (1). The upper limit of the usage amount of the OH type anion exchange resin is not particularly limited, but can be set to, for example, 30 molar equivalents or less from the viewpoint of economy.

  The organic acid is used in an amount of 20 molar equivalents or more, preferably 30 molar equivalents or more based on the salt represented by the above formula (1). Although the upper limit of the usage-amount of an organic acid is not specifically limited, From an economical viewpoint, it can be 40 mol equivalent or less, for example.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to this.

Example 1
Water (500 mL) was added to taurine (50 g, 400 mmol) and uniformly dissolved, and then passed through 100 g (active site: about 200 mmol) of an anion exchange resin (OH form) (first step).

  Tetraethylphosphonium bromide (2.25 g, 10 mmol) was uniformly dissolved in 20 mL of ion-exchanged water and repeatedly passed through the anion-exchange resin (second step). A portion of the resulting aqueous solution was collected and a 1N silver nitrate aqueous solution was added to confirm that it was not cloudy (no bromine ions remained), and then the original aqueous solution was dried under reduced pressure. 5 ml was added and ice-cooled, and the precipitated unreacted taurine was filtered off. The obtained filtrate was dried under reduced pressure. In addition, when the head space gas of the obtained concentrate was analyzed by GC-MS, peaks were observed at 1.3 minutes, 1.4 minutes, and 6.6 minutes, respectively, as shown in FIG. When mass spectrometry was performed on the peak at 6.6 minutes, it was confirmed to be triethylphosphine, which is an odor component (see FIG. 2).

  The above concentrate is dissolved again in 10 mL of ion-exchanged water, 10 g of activated carbon is added, and the mixture is stirred for 3 hours (the third step), followed by drying under reduced pressure to obtain 2.4 g of a purified tetraethylphosphonium taurine salt (yield) 90%, 9 mmol).

The result of ¹ H-NMR measurement of this product is as shown in FIG. 4, and the production of the target product was confirmed from the chemical shift of proton and the integrated intensity. Moreover, when the head space gas of this product was analyzed by GC-MS, as shown in FIG. 3, triethylphosphine as an odor component was not detected.

(Example 2)
Water (500 mL) was added to taurine (50 g, 400 mmol) and uniformly dissolved, and then passed through 100 g (active site: about 200 mmol) of an anion exchange resin (OH form) (first step).

  Tetraethylphosphonium bromide (2.25 g, 10 mmol) was uniformly dissolved in 20 mL of ion-exchanged water and repeatedly passed through the anion-exchange resin (second step). A portion of the resulting aqueous solution was collected and 1N silver nitrate aqueous solution was added to confirm that it was not cloudy. Then, the original aqueous solution was dried under reduced pressure, and 20 ml of acetonitrile and 5 ml of methanol were added to it and cooled with ice to precipitate. Unreacted taurine was filtered off. The obtained filtrate was dried under reduced pressure.

  About this, nitrogen refinement | circulation was performed at 200 degreeC for 10 hours (3rd process), and the purified ionic liquid 2.5g (yield 92%, 9.2 mmol) was obtained.

The result of ¹ H-NMR measurement of this product is the same as that shown in FIG. 4, and the production of the target product was confirmed from the chemical shift of proton and the integrated intensity. Further, when the head space gas of this product was analyzed by GC-MS, triethylphosphine as an odor component was not detected as in Example 1.

(Example 3)
Water (500 mL) was added to taurine (50 g, 400 mmol) and uniformly dissolved, and then passed through 100 g (active site: about 200 mmol) of an anion exchange resin (OH form) (first step).

  Tetramethylphosphonium bromide 1.71 g (10 mmol) was uniformly dissolved in 20 mL of ion-exchanged water, and repeatedly passed through the anion-exchange resin (second step). A portion of the resulting aqueous solution was collected and 1N silver nitrate aqueous solution was added to confirm that it was not cloudy. Then, the original aqueous solution was dried under reduced pressure, and 20 ml of acetonitrile and 5 ml of methanol were added to it and cooled with ice to precipitate. Unreacted taurine was filtered off. The obtained filtrate was dried under reduced pressure.

  This was dissolved again in 10 mL of ion-exchanged water, 10 g of activated carbon was added, and the mixture was stirred for 3 hours (the third step). After that, it was separated and dried under reduced pressure to obtain 1.9 g of purified tetramethylphosphonium taurate (yield 90%). %, 9 mmol).

The result of ¹ H-NMR measurement of this product is as shown in FIG. 5, and the production of the target product was confirmed from the chemical shift of proton and the integrated intensity. Moreover, although the tetramethylphosphonium taurine salt before the third step had an odor, this product had no odor remaining.

Claims (3)

A first step of bringing an organic acid aqueous solution into contact with an OH-type anion exchange resin;
A second step of bringing the aqueous solution containing a salt represented by the following formula (1) into contact with the anion exchange resin carrying the organic acid anion obtained in the first step;
A third step of deodorizing the ionic liquid obtained in the second step, and a method for producing the ionic liquid,
The manufacturing method of an ionic liquid using 10 mol equivalent or more of said OH type anion exchange resins, and 20 mol equivalent or more of said organic acids with respect to the salt represented by said Formula (1).

[In the formula (1), Z represents a phosphorus atom or a nitrogen atom, R ^{1 to} R ⁴ each independently represents a cyclic, linear or branched alkyl group having 1 to 12 carbon atoms, and X represents a halogen atom. Show. ]   The method for producing an ionic liquid according to claim 1, wherein the deodorization in the third step is performed by a method of contacting a porous material having an organic substance adsorption ability and / or a method of heating in a gas stream.   The method for producing an ionic liquid according to claim 1, wherein the organic acid is a sulfonic acid or an amino acid.

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