Method for recovering ionic liquid

Abstract

Provided is a method for easily and efficiently recovering an ionic liquid from a mixed solution containing the ionic liquid and an organic acid. Provided is a method for recovering an ionic liquid from a mixed solution containing an ionic liquid and an organic acid, the ionic liquid being water-soluble, the method being characterized in that at least one substance selected from the group consisting of water and an organic solvent (excluding an organic acid) is added to the mixed solution, and the organic acid is separated by extraction.

Description

Technical Field

[0001] The present disclosure relates to a method for recovering ionic liquids by extraction. Background Art

[0002] In recent years, ionic liquids have been proposed as solvents for dissolving biomass containing polysaccharides such as cellulose and lignocellulose (hereinafter sometimes referred to as "polysaccharide-containing biomass"), and technologies for derivatizing polysaccharides in a homogeneous reaction using these ionic liquids have been introduced. Ionic liquids have extremely low volatility, and there is no risk of pollution or fire due to volatilization. They also have a strong ability to dissolve cellulose, etc., and therefore are being researched and developed as solvents for processing polysaccharides.

[0003] For example, Example 1 of Patent Document 1 describes the following: 120 mg of bagasse (sugarcane residue) was dissolved in 4 g of 1-ethyl-3-methylimidazolium acetate as an ionic liquid (bagasse concentration in the ionic liquid: 3 wt %), and after vacuum drying at 80° C. with stirring overnight, 4 mL of isopropenyl acetate was added to the reaction system, the obtained reaction solution was reprecipitated with methanol, and a solid polysaccharide derivative (cellulose acetate) was obtained by filtration.

[0004] Here, since ionic liquids are very expensive, a method for recovering and reusing them after the reaction is completed has been studied. For example, Patent Document 2 describes a method for separating and recovering ionic liquids from a mixed solution in which two or more solutes containing ionic liquids are dissolved using an ion exchange membrane. In addition, Patent Document 3 describes the following method: for an ionic liquid having a quaternary ammonium skeleton containing an alkoxyalkyl group or a nitrogen-containing hetero-five-membered ring skeleton containing an alkoxyalkyl group as a cationic component and an amino group as an anionic component, after crystallization, the ionic liquid is washed with a solvent such as ethyl acetate to separate and recover the ionic liquid. In addition, Patent Document 4 describes the following method: after dissolving an ionic liquid containing impurities in a mixed solvent of a polar aprotic organic solvent and a non-polar organic solvent, the temperature of the solution is lowered, and the ionic liquid is crystallized from the solution to separate and recover it. In addition, Patent Document 5 describes the following method for refining ionic liquids: partially crystallize the ionic liquid from its melt, and separate the crystallized product from the remaining melt.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2016 / 068053

[0008] Patent Document 2: Japanese Patent Application Publication No. 2015-96255

[0009] Patent Document 3: Japanese Patent Application Publication No. 2012-144441

[0010] Patent Document 4: Japanese Patent Application Publication No. 2010-184902

[0011] Patent Document 5: Japanese Patent Application Publication No. 2008-523005 Summary of the invention

[0012] Problems to be solved by the invention

[0013] However, as described in Patent Document 1, when producing cellulose acetate from polysaccharide-containing biomass, an esterification reaction of the polysaccharide-containing biomass is carried out in the presence of the polysaccharide-containing biomass as a raw material, an esterifying agent, and an ionic liquid as a solvent, but an organic acid derived from the esterifying agent is produced as a by-product of the reaction. Therefore, the reaction solution after the esterification reaction becomes a mixture containing an organic acid and an ionic liquid. Although the reason for such a mixture is not clear, it may be difficult to separate and recover the ionic liquid from the mixed solution due to the interaction between the organic acid and the ionic liquid.

[0014] Therefore, an object of the present disclosure is to provide a method for simply and efficiently recovering an ionic liquid from a mixed solution containing an ionic liquid and an organic acid.

[0015] Solutions for solving problems

[0016] The inventors of the present disclosure have conducted intensive research to solve the above-mentioned problems and have found that the ionic liquid can be easily and efficiently recovered by adding at least one selected from the group consisting of water and an organic solvent to a mixed solution containing an ionic liquid and an organic acid and performing extraction. The present invention was completed based on these findings.

[0017] That is, the present disclosure provides a method for recovering an ionic liquid, characterized in that it is a method for recovering an ionic liquid from a mixed solution containing an ionic liquid and an organic acid, wherein the ionic liquid is water-soluble, at least one selected from the group consisting of water and an organic solvent (but excluding the organic acid) is added to the mixed solution, and the organic acid is separated by extraction.

[0018] The above-mentioned ionic liquid preferably contains an imidazolium cation or a quaternary ammonium cation as a cationic component.

[0019] The above-mentioned ionic liquid preferably contains a carboxylate anion as an anion component.

[0020] The above-mentioned organic acid is preferably a carboxylic acid.

[0021] The organic solvent is preferably at least one selected from the group consisting of ethers, ketones, esters, aryls, alkanes, and cycloalkanes.

[0022] The organic solvent is preferably at least one selected from the group consisting of ethers, ketones, and esters.

[0023] The above organic acid is preferably C 1-7 of carboxylic acid.

[0024] Effects of the Invention

[0025] According to the method for recovering an ionic liquid of the present disclosure, the ionic liquid can be recovered simply and efficiently from a mixed solution containing an ionic liquid and an organic acid. DETAILED DESCRIPTION

[0026] The method for recovering an ionic liquid disclosed in the present invention is a method for recovering an ionic liquid from a mixed solution containing an ionic liquid and an organic acid, characterized in that the ionic liquid is water-soluble, at least one selected from the group consisting of water and an organic solvent (but excluding an organic acid) is added to the mixed solution, and the organic acid is separated by extraction. Hereinafter, the method for recovering an ionic liquid disclosed in the present invention is sometimes referred to as "the method disclosed in the present invention". In addition, at least one selected from the group consisting of water and an organic solvent (but excluding an organic acid) is sometimes described as water and / or an organic solvent (but excluding an organic acid).

[0027] [Mixed liquid]

[0028] The mixed solution (A) and the mixed solution (B) are described below. In this specification, a mixed solution containing an ionic liquid and an organic acid is referred to as a mixed solution (B). In addition, in this specification, a mixed solution containing an ionic liquid, an organic acid, water, and an organic solvent (but excluding the organic acid) is referred to as a mixed solution (A). The mixed solution (A) contains an ionic liquid, an organic acid, water, and an organic solvent (but excluding the organic acid). There is no particular limitation as long as the ionic liquid is water-soluble, but it is preferred to add water and / or an organic solvent (but excluding the organic acid) to the mixed solution (B) containing the ionic liquid and the organic acid. There is no particular limitation as long as the ionic liquid is water-soluble. For example, it can be a mixed solution containing a reaction product obtained when an ionic liquid is used as a solvent and a specific raw material is esterified by an esterifying agent or the like (hereinafter sometimes referred to as "mixed solution (B1)"). The mixed solution (B1) contains, for example, an esterified product (esterified product of the raw material) as a target, an organic acid derived from an esterifying agent, and an ionic liquid. In addition, the mixed solution (B1) may further contain unreacted raw materials, unreacted esterification agent, byproducts other than the above-mentioned organic acid, solvents other than the ionic liquid, etc. In addition, the mixed solution (B1) may be a mixed solution in which a part or all of the components other than the ionic liquid and the organic acid are removed by a known or customary method. That is, the mixed solution (B1) only needs to contain at least the organic acid derived from the esterification agent and the ionic liquid.

[0029] As a mixed solution (B1), the case where the above-mentioned raw material is a polysaccharide is described below. That is, it means that the mixed solution (B) is a mixed solution obtained when the polysaccharide is esterified by an esterifying agent using an ionic liquid as a solvent (hereinafter sometimes referred to as "mixed solution (B2)"). The mixed solution (B2) contains, for example, an esterified product of the polysaccharide as the target, an organic acid derived from the esterifying agent, and an ionic liquid. The mixed solution (B2) may also contain unreacted polysaccharides, unreacted esterifying agents, by-products other than the above-mentioned organic acids, solvents other than ionic liquids, and the like. In addition, the mixed solution (B2) may also be a mixed solution in which a part or all of the components other than the ionic liquid and the organic acid are removed by a known or customary method.

[0030] In summary, the mixed solution (B1) is an example of a specific embodiment of the mixed solution (B), and is a mixed solution (B) containing a reaction product obtained when an ionic liquid is used as a solvent and a specific raw material is esterified by an esterifying agent, etc. The mixed solution (B2) is an example of a further specific embodiment of the mixed solution (B1), and is a mixed solution (B) in which the raw material that becomes an esterified product by an esterifying agent is a polysaccharide, and the mixed solution (B) is a mixed solution as a concept including the mixed solution (B1) and the mixed solution (B2). Here, in this embodiment, the mixed solution (B) is not limited to the mixed solution (B1) or the mixed solution (B2), and it is re-remarked here.

[0031] Hereinafter, when the mixed solution (B) is the mixed solution (B1), the raw materials, the esterification agent, the ionic liquid, and the solvent other than the ionic liquid will be described in detail.

[0032] <Raw Materials>

[0033] First, the raw materials are described. The raw materials refer to starting materials that are esterified with an esterifying agent.

[0034] The raw material is preferably a polysaccharide. Here, as described above, when the raw material is a polysaccharide, the mixed solution (B1) means the mixed solution (B2).

[0035] The above-mentioned polysaccharides may be biomass containing polysaccharides (polysaccharide-containing biomass). The above-mentioned polysaccharide-containing biomass is not particularly limited as long as it contains polysaccharides, and examples thereof include bagasse (sugarcane residue): kenaf; fir; wood such as eucalyptus, red pine, tree, eucalyptus, cypress, birch, spruce, etc.; shells of crustaceans such as crabs and prawns; cereals such as rice, wheat, corn, sorghum; potatoes such as potatoes, sweet potatoes, cassava, etc.; other raw materials derived from cellulose plants (pulp waste liquid, rice straw, husks, fruit fibers, fruit shells such as ginkgo, empty fruit bunches, etc.). In addition, pulp refined from these biomasses may also be used. It should be noted that the above-mentioned polysaccharide-containing biomass may be in a polysaccharide state by a process of separating and extracting polysaccharides (such as cellulose) through various pretreatments such as cutting and drying as needed. The above-mentioned polysaccharides may be used only one or more.

[0036] The polysaccharides are not particularly limited, and examples thereof include cellulose, hemicellulose, xylan, mannan, glucomannan, glucuronoxylan, starch, amylose, amylopectin, glycogen, dextrin, pectin, chitin, chitosan, agarose, carrageenan, isolichenan, laminaran, lichenin, glucan, inulin, levan, fructan, galactan, arabinan, pentosan, alginic acid, pectic acid, protuberic acid, colominic acid, porphyran, fucoidan, ascosan, locust bean gum, guar gum, tamarind gum, tara gum, and gum arabic.

[0037] <Esterifying agent>

[0038] Next, the esterifying agent is described. The esterifying agent refers to a compound used to esterify raw materials such as polysaccharides.

[0039] The esterifying agent is not particularly limited, and a compound corresponding to the type of the target esterified product can be appropriately selected and used. Among them, the esterifying agent is preferably one or more selected from the group consisting of chain ester compounds, cyclic ester compounds, unsaturated aldehydes, saturated aldehydes, acyl halides, acid anhydrides and allyl alcohol. Among them, acid anhydrides are preferred from the viewpoint of operability and the yield of the obtained esterified product. The esterifying agent can be used alone or in combination of two or more.

[0040] The chain ester compound is not particularly limited, and examples thereof include compounds such as carboxylic acid alkyl esters such as methyl acetate and carboxylic acid alkenyl esters such as isopropenyl acetate and vinyl acetate.

[0041] The cyclic ester compound is not particularly limited, and examples thereof include lactones such as β-propiolactone, δ-valerolactone, γ-butyrolactone, ε-caprolactone, α,α-dimethyl-β-propiolactone, β-ethyl-δ-valerolactone, α-methyl-ε-caprolactone, β-methyl-ε-caprolactone, γ-methyl-ε-caprolactone, and 3,3,5-trimethyl-ε-caprolactone; and lactides such as glycolide and lactide.

[0042] The unsaturated aldehyde is not particularly limited, and examples thereof include aromatic aldehydes such as 2-butenal, 2-hexenal, 2-decenal, 2-undecenal, 2-dienal, 2,4-heptadienal, 2,4-decadienal, cinnamaldehyde, and benzaldehyde.

[0043] The saturated aldehyde is not particularly limited, and examples thereof include propionaldehyde, hexanal, octanal, nonanal, and the like.

[0044] The acid halide is not particularly limited, and examples thereof include carboxylic acid halides such as carboxylic acid fluorides, carboxylic acid chlorides, carboxylic acid bromides, and carboxylic acid iodides. Specific examples of the carboxylic acid halide include acetyl fluoride, acetyl chloride, acetyl bromide, acetyl iodide, propionyl fluoride, propionyl chloride, propionyl bromide, propionyl iodide, butyryl fluoride, butyryl chloride, butyryl bromide, butyryl iodide, benzoyl fluoride, benzoyl chloride, benzoyl bromide, and benzoyl iodide.

[0045] The acid anhydride is not particularly limited, and examples thereof include acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, caproic anhydride, heptanoic anhydride, caprylic anhydride, nonanoic anhydride, capric anhydride, lauric anhydride, myristic anhydride, palmitic anhydride, stearic anhydride, oleic anhydride, linoleic anhydride, linolenic anhydride, benzoic anhydride, phthalic anhydride, maleic anhydride, succinic anhydride, etc. Among them, acetic anhydride is particularly preferred.

[0046] The allyl alcohol is not particularly limited, and examples thereof include methyl allyl alcohol, propenyl alcohol, 2-hydroxymethyl-1-butene, and α-hydroxymethylstyrene.

[0047] <Ionic Liquids>

[0048] Next, the ionic liquid is described. An ionic liquid refers to a solvent (particularly a solvent for dissolving a raw material) for dissolving and / or dispersing a raw material (e.g., a polysaccharide). Specific examples of ionic liquids will be described later in the item "Ionic liquids". Therefore, specific examples of ionic liquids are omitted here. As ionic liquids, each specific ionic liquid exemplified in the item [Ionic liquids] can be used.

[0049] <Solvents other than ionic liquids [Solvent (S)]>

[0050] Next, the solvents other than the ionic liquid are described. Here, in this specification, the above-mentioned solvent is sometimes referred to as "solvent (S)". The solvent (S) is a solvent that can further exhibit the function of dissolving and / or dispersing the raw materials when used together with the ionic liquid, and is also called a co-solvent with the ionic liquid.

[0051] The solvent (S) is not particularly limited and can be appropriately selected in consideration of its compatibility with the ionic liquid. In addition, when the raw material is a polysaccharide, that is, when the mixed solution (B) is a mixed solution obtained by esterifying the polysaccharide, the solvent (S) can be appropriately selected in consideration of its affinity with the polysaccharide and the ester of the polysaccharide, the viscosity of the mixture of the polysaccharide and the ionic liquid, etc. In addition, the solvent (S) is preferably a solvent that does not react with the ionic liquid, or a solvent that has high solubility in the polysaccharide and the ester of the polysaccharide in a state mixed with the ionic liquid. The solvent (S) can be used alone or in combination of two or more.

[0052] Specific examples of the solvent (S) include: nitriles such as acetonitrile; sulfoxides such as dimethyl sulfoxide (DMSO); sulfones such as cyclic sulfones (e.g., sulfolane); ethers such as cyclic ethers (e.g., 1,3-dioxolane, 1,4-dioxane, tetrahydrofuran); amides such as N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMAc); lactams such as N-methyl-2-pyrrolidone (NMP); lactones such as γ-butyrolactone; and amines such as pyridine. Among them, from the viewpoint of compatibility with ionic liquids and the solubility of esters of polysaccharides, the above-mentioned solvent (S) is preferably at least one selected from the group consisting of sulfoxides, sulfones, amides and lactams, more preferably at least one selected from the group consisting of dimethyl sulfoxide (DMSO), sulfolane, N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP), further preferably at least one selected from the group consisting of N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP), and particularly preferably N-methyl-2-pyrrolidone (NMP).

[0053] As the solvent (S), an organic solvent blended in the mixed solution (B) may be used. When an organic solvent is used as the solvent (S), the extraction operation can be performed without blending (adding) an organic solvent to the obtained mixed solution (B1), which is preferred from the viewpoint that it can be achieved without complicated operations.

[0054] The above is a detailed description of the raw materials, the esterification agent, the ionic liquid, and the solvent other than the ionic liquid in the case where the mixed liquid (B) is the mixed liquid (B1).

[0055] [extraction]

[0056] The method disclosed in the present invention is characterized in that, for a mixed solution (B) containing an ionic liquid and an organic acid, the ionic liquid and the organic acid are separated by an extraction process. Specifically, water and / or an organic solvent (but excluding the organic acid) are added to the mixed solution (B), water is brought into contact with the organic solvent, and the mixed solution (A) is prepared, and the ionic liquid and the organic acid are separated by the obtained mixed solution (A). This series of operations is referred to as extraction. Hereinafter, the organic solvent (but excluding the organic acid) is also referred to as an organic solvent (Or) as described later. The extraction operation disclosed in the present invention is liquid-liquid extraction.

[0057] That is, the method disclosed in the present invention is characterized in that, during extraction, water and / or the above-mentioned organic solvent (Or) are added to a mixed solution (B) containing at least an ionic liquid and an organic acid. The method of adding water and / or the above-mentioned organic solvent (Or) to the mixed solution (B), that is, the method of preparing the mixed solution (A) is not particularly limited. For example, as a method for preparing the mixed solution (A), any of the following methods can be listed: [1] A method of preparing the mixed solution (A) by adding the above-mentioned organic solvent (Or) to a mixed solution (B) containing an ionic liquid, an organic acid and water; [2] A method of preparing the mixed solution (A) by adding water and the above-mentioned organic solvent (Or) to a mixed solution (B) containing an ionic liquid, an organic acid and water; [3] A method of preparing the mixed solution (A) by adding water to a mixed solution (B) containing an ionic liquid, an organic acid and the above-mentioned organic solvent (Or); [4] A method of preparing the mixed solution (A) by adding water and the above-mentioned organic solvent (Or) to a mixed solution (B) containing an ionic liquid, an organic acid and the above-mentioned organic solvent (Or); ) to prepare a mixed solution (A); [5] a method for preparing a mixed solution (A) by adding water and the above-mentioned organic solvent (Or) to a mixed solution (B) containing an ionic liquid and an organic acid; [6] a method for preparing a mixed solution (A) by adding water to a mixed solution containing an ionic liquid, an organic acid, water and the above-mentioned organic solvent (Or); [7] a method for preparing a mixed solution (A) by adding the above-mentioned organic solvent (Or) to a mixed solution containing an ionic liquid, an organic acid, water and the above-mentioned organic solvent (Or); [8] a method for preparing a mixed solution (A) by adding water and the above-mentioned organic solvent (Or) to a mixed solution containing an ionic liquid, an organic acid, water and the above-mentioned organic solvent (Or). Water and / or the organic solvent (Or) may be blended (added) after the ionic liquid and the organic acid are mixed, or may be mixed together with the ionic liquid and the organic acid.

[0058] When the mixed liquid (B) is a mixed liquid (B1), it may be a scheme in which water and / or an organic solvent (Or) are formulated (added) in a system before the esterification reaction of a specific raw material to carry out various reactions, resulting in at least one selected from the group consisting of water and an organic solvent (Or) being formulated in the mixed liquid. Alternatively, it may be a scheme in which at least one selected from the group consisting of water and an organic solvent (Or) is formulated (added) to the mixed liquid after the reaction (i.e., the mixed liquid (B1)).

[0059] In the method disclosed in the present invention, the mixed solution (B) can be directly subjected to an extraction operation (i.e., without pretreatment), or the mixed solution (B) can be subjected to an extraction operation after pretreatment. As such a pretreatment, treatment with a strong acid such as sulfuric acid, hydrochloric acid, and nitric acid can be cited. It can also be considered that if a strong acid is used for pretreatment, the ionic liquid in the mixed solution (B) becomes a strong acid salt, and the amount of ionic liquid moved to the aqueous phase side increases through subsequent extraction. However, in the method disclosed in the present invention, since the mixed solution (B) contains specific components, the organic acid can be separated by extraction, and as a result, the ionic liquid can be recovered simply and efficiently. That is, the method disclosed in the present invention does not require the above-mentioned pretreatment to exert the above-mentioned effective effect. Therefore, the mixed solution (B) is preferably subjected to an extraction operation directly (i.e., without pretreatment). In other words, the structural formula of the ionic liquid recovered by the method disclosed in the present invention is preferably the same as the structural formula of the ionic liquid before extraction (in the mixed solution (B)).

[0060] The ionic liquid is separated from the organic acid by extracting the mixed solution (B). In addition, the ionic liquid can be separated from the organic acid by adding water and / or an organic solvent (Or) to the mixed solution (B) and performing extraction. Here, it is preferred that the organic acid is extracted to the organic solvent phase side (oil phase) and the ionic liquid is extracted to the water phase side. Thus, the ionic liquid is recovered in the form of being separated from the organic acid. Specifically, the ionic liquid and water mixture is subjected to, for example, distillation, and the like, and finally the ionic liquid is recovered.

[0061] The operation of recovering the ionic liquid by extracting the mixed liquid (B) (extraction operation) can be carried out in an apparatus that brings the aqueous phase and the oil phase (organic solvent phase) into contact with each other. Examples of such apparatus include extraction apparatuses such as a mixed clarification type extraction tower, a porous plate type, a packed tower type, a foam tower type, a vibrating porous plate type, a stirring mixing type, a pulsating packed type, and a centrifugal extraction type.

[0062] The temperature during extraction of the mixed solution (B) is not particularly limited, but is, for example, preferably 0 to 100°C, more preferably 1 to 90°C, further preferably 3 to 80°C, and particularly preferably 5 to 70°C.

[0063] The pressure during extraction of the mixed solution (B) is not particularly limited, but is, for example, preferably 10 to 2000 hPa, more preferably 100 to 1500 hPa, and further preferably 500 to 1200 hPa (eg, normal pressure).

[0064] By the above extraction operation, the above ionic liquid can be separated from the mixed solution (B). Usually, by the above extraction operation, an aqueous phase mainly containing ionic liquid and water and an oil phase mainly containing organic acid and organic solvent are obtained. The above ionic liquid can also be separated from the aqueous phase containing the above ionic liquid and water by a known or conventional purification method such as evaporation of water. That is, according to the method disclosed in the present invention, a high-purity ionic liquid can be obtained by a simple method such as extraction.

[0065] [Ionic Liquids]

[0066] Next, the ionic liquid is described. The ionic liquid is a liquid component separated from the organic acid by the above-mentioned extraction operation (extraction process). In addition, when the mixed solution (B) is the mixed solution (B1), the ionic liquid is also a solvent for dissolving and / or dispersing the raw material (for example, polysaccharides) (particularly a solvent for dissolving the raw material). The ionic liquid disclosed in the present invention is water-soluble.

[0067] The ionic liquid disclosed in the present invention is not particularly limited as long as it is a water-soluble ionic liquid, and can be, for example, at least one water-soluble ionic liquid selected from the group consisting of an acidic ionic liquid, a neutral ionic liquid, and a basic ionic liquid. It should be noted that in this specification, "ionic liquid" refers to a salt composed of a cationic component and an anionic component, and its liquidity can be determined by the acid dissociation constant (pKa, calculated value in vacuum) of the conjugate acid of the anion, for example, the acid dissociation constant of the basic ionic liquid is 2 to 19. Only one of the above-mentioned ionic liquids can be used, or two or more can be used.

[0068] ・Cationic ingredients

[0069] Examples of the cationic component in the ionic liquid include imidazolium cations, pyridinium cations, pyrrolidinium cations, piperidinium cations, quaternary ammonium cations, and quaternary phosphonium cations.

[0070] Examples of the imidazolium cation include a cation represented by the following formula (1): The cation represented by the formula (1) includes tautomers thereof and a cation represented by a structural formula having a resonance relationship with the formula (1).

[0071] [Chemical formula 1]

[0072]

[0073] In formula (1), R 1 and R3 are the same or different and are substituted or unsubstituted alkyl, alkenyl, alkoxyalkyl, or substituted or unsubstituted phenyl, R 2 , R 4 and R 5 are the same or different and are a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an alkoxyalkyl group, or a substituted or unsubstituted phenyl group.

[0074] As R 1 ~R 5 The substituted or unsubstituted alkyl group in the alkyl group may include, for example, a linear or branched alkyl group having 1 to 20 (preferably 1 to 10, more preferably 2 to 6, and further preferably 2 to 4) carbon atoms, such as a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a butyl group, a hexyl group, an octyl group, etc. The terminal of these alkyl groups may be bonded to a sulfo group. In addition, as alkenyl groups, linear or branched alkenyl groups having 2 to 20 (preferably 2 to 10, more preferably 2 to 6, and further preferably 2 to 4) carbon atoms, such as a vinyl group, a 1-propenyl group, a 2-propenyl group, a 1-butenyl group, a 2-butenyl group, a 1-pentenyl group, a 2-pentenyl group, a 1-hexenyl group, a 2-hexenyl group, and a 1-octenyl group may be included. In addition, examples of the alkoxyalkyl group include linear or branched alkoxyalkyl groups having 2 to 20 (preferably 2 to 10, more preferably 2 to 6, and even more preferably 2 to 4) carbon atoms, such as methoxymethyl, ethoxymethyl, 1-methoxyethyl, 2-methoxyethyl, 1-ethoxyethyl, and 2-ethoxyethyl. Further, examples of the substituted or unsubstituted phenyl group include phenyl groups optionally substituted with 1 to 2 groups selected from hydroxyl groups, halogen atoms, lower alkoxy groups, lower alkenyl groups, methylsulfonyloxy groups, substituted or unsubstituted lower alkyl groups, substituted or unsubstituted amino groups, substituted or unsubstituted phenyl groups, substituted or unsubstituted phenoxy groups, and substituted or unsubstituted pyridyl groups.

[0075] R 1 and R 3 It is preferably an alkyl group, an alkenyl group, or a substituted or unsubstituted phenyl group, and more preferably a linear alkyl group having 1 to 6 carbon atoms. 1 and R 3 One of them is a straight-chain alkyl group having 1 to 4 carbon atoms, and the other is a straight-chain alkyl group having 2 to 6 carbon atoms, and the number of carbon atoms of these alkyl groups is different. 2 , R 4 and R 5 It is preferably a hydrogen atom, an alkyl group, an alkenyl group, or a substituted or unsubstituted phenyl group, and more preferably a hydrogen atom or an alkyl group.

[0076] Examples of the imidazolium cation include 1,3-dimethylimidazolium, 1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-octyl-3-methylimidazolium, 1-decyl-3-methylimidazolium, 1-tetradecyl-3-methylimidazolium, 1-hexadecyl-3-methylimidazolium, 1-octadecyl-3-methylimidazolium, 1-allyl-3-methylimidazolium, 1-ethyl-2,3-dimethylimidazolium, 1-butyl-2,3-dimethylimidazolium, and 1-hexyl-2,3-dimethylimidazolium. Among them, the 1-ethyl-3-methylimidazolium cation (Emim) is particularly preferred. + ).

[0077] Examples of the pyridinium cation include a cation represented by the following formula (2). The cation represented by formula (2) includes tautomers thereof and a cation represented by a structural formula having a resonance relationship with formula (2).

[0078] [Chemical formula 2]

[0079]

[0080] In formula (2), R 6 is an alkyl group, an alkenyl group, an alkoxyalkyl group, or a substituted or unsubstituted phenyl group, R 7 ~R 11 The same or different groups are a hydrogen atom, an alkyl group, an alkenyl group, an alkoxyalkyl group, or a substituted or unsubstituted phenyl group.

[0081] As R 6 ~R 11 The alkyl, alkenyl, alkoxyalkyl, and substituted or unsubstituted phenyl groups in the formula (1) are exemplified by R as a cation. 1 ~R 5 The same groups as those described above.

[0082] R 6 It is preferably an alkyl group, and more preferably a linear alkyl group having 1 to 6 carbon atoms. 6 ~R 11 It is preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom.

[0083] Examples of the pyridinium cation include pyridinium cations such as 1-ethylpyridinium, 1-butylpyridinium, 1-hexylpyridinium, 1-butyl-4-methylpyridinium, 1-butyl-3-methylpyridinium, 1-hexyl-4-methylpyridinium, 1-hexyl-3-methylpyridinium, 1-octyl-4-methylpyridinium, 1-octyl-3-methylpyridinium, 1-butyl-3,4-dimethylpyridinium, and 1-butyl-3,5-dimethylpyridinium, among which 1-octyl-4-methylpyridinium cation is particularly preferred.

[0084] Examples of the pyrrolidinium cation include a cation represented by the following formula (3). The cation represented by formula (3) also includes tautomers thereof.

[0085] [Chemical formula 3]

[0086]

[0087] In formula (3), R 12 and R 13 are the same or different and are alkyl, alkenyl, alkoxyalkyl, or substituted or unsubstituted phenyl, R 14 ~R 21 The same or different groups are a hydrogen atom, an alkyl group, an alkenyl group, an alkoxyalkyl group, or a substituted or unsubstituted phenyl group.

[0088] As R 12 ~R 21 The alkyl, alkenyl, alkoxyalkyl, and substituted or unsubstituted phenyl groups in the formula (1) are exemplified by R as a cation. 1 ~R 5 The same groups as those described above.

[0089] R 12 and R 13 It is preferably an alkyl group, and more preferably a linear alkyl group having 1 to 6 carbon atoms. 14 ~R 21 It is preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom.

[0090] As the pyrrolidinium cation, a 1-butyl-1-methylpyrrolidinium cation is particularly preferred.

[0091] Examples of the piperidinium cation include a cation represented by the following formula (4). The cation represented by formula (4) also includes tautomers thereof.

[0092] [Chemical formula 4]

[0093]

[0094] In formula (4), R22 and R 23 are the same or different and are alkyl, alkenyl, alkoxyalkyl, or substituted or unsubstituted phenyl, R 24 ~R 33 The same or different groups are a hydrogen atom, an alkyl group, an alkenyl group, an alkoxyalkyl group, or a substituted or unsubstituted phenyl group.

[0095] As R 22 ~R 33 The alkyl, alkenyl, alkoxyalkyl, and substituted or unsubstituted phenyl groups in the formula (1) are exemplified by R as a cation. 1 ~R 5 The same groups as those described above.

[0096] R 22 and R 23 It is preferably an alkyl group, and more preferably a linear alkyl group having 1 to 6 carbon atoms. 24 ~R 33 It is preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom.

[0097] As the piperidinium cation, a 1-butyl-1-methylpiperidinium cation is preferred.

[0098] Examples of the quaternary ammonium cation include an ammonium cation represented by the following formula (5). The cation represented by formula (5) also includes tautomers thereof.

[0099] [Chemical formula 5]

[0100]

[0101] In formula (5), R 34 ~R 37 The same or different groups are alkyl, alkenyl, alkoxyalkyl, or substituted or unsubstituted phenyl.

[0102] As R 34 ~R 37Examples of the alkyl group in the alkyl group include a linear or branched alkyl group having 1 to 20 (preferably 1 to 10, more preferably 2 to 6, and even more preferably 2 to 4) carbon atoms, such as a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a butyl group, a hexyl group, and an octyl group. In addition, examples of the alkenyl group include a linear or branched alkenyl group having 2 to 20 (preferably 2 to 10, more preferably 2 to 6, and even more preferably 2 to 4) carbon atoms, such as a vinyl group, a 1-propenyl group, a 2-propenyl group, a 1-butenyl group, a 2-butenyl group, a 1-pentenyl group, a 2-pentenyl group, a 1-hexenyl group, a 2-hexenyl group, and a 1-octenyl group. In addition, examples of the alkoxyalkyl group include linear or branched alkoxyalkyl groups having 2 to 20 (preferably 2 to 10, more preferably 2 to 6, and even more preferably 2 to 4) carbon atoms, such as methoxymethyl, ethoxymethyl, 1-methoxyethyl, 2-methoxyethyl, 1-ethoxyethyl, and 2-ethoxyethyl. Further, examples of the substituted or unsubstituted phenyl group include phenyl groups optionally substituted with 1 to 2 groups selected from hydroxyl groups, halogen atoms, lower alkoxy groups, lower alkenyl groups, methylsulfonyloxy groups, substituted or unsubstituted lower alkyl groups, substituted or unsubstituted amino groups, substituted or unsubstituted phenyl groups, substituted or unsubstituted phenoxy groups, and substituted or unsubstituted pyridyl groups.

[0103] R 34 ~R 37 An alkyl group is preferred, and a linear alkyl group having 1 to 6 carbon atoms is more preferred.

[0104] Examples of the quaternary ammonium cation include ammonium cations such as trimethylpropylammonium, trimethylbutylammonium, triethylmethylammonium, trioctylmethylammonium, tetramethylammonium, tetraethylammonium, tetrabutylammonium, tetrapentylammonium, and tetrahexylammonium.

[0105] Examples of the quaternary phosphonium cation include phosphonium cations represented by the following formula (6). The cation represented by formula (6) also includes tautomers thereof.

[0106] [Chemical formula 6]

[0107]

[0108] In formula (6), R 38 ~R 41 The same or different groups are alkyl, alkenyl, alkoxyalkyl, or substituted or unsubstituted phenyl.

[0109] As R 38 ~R 41Examples of the alkyl group in the alkyl group include a linear or branched alkyl group having 1 to 20 (preferably 1 to 10, more preferably 2 to 6, and even more preferably 2 to 4) carbon atoms, such as a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a butyl group, a hexyl group, and an octyl group. In addition, examples of the alkenyl group include a linear or branched alkenyl group having 2 to 20 (preferably 2 to 10, more preferably 2 to 6, and even more preferably 2 to 4) carbon atoms, such as a vinyl group, a 1-propenyl group, a 2-propenyl group, a 1-butenyl group, a 2-butenyl group, a 1-pentenyl group, a 2-pentenyl group, a 1-hexenyl group, a 2-hexenyl group, and a 1-octenyl group. In addition, examples of the alkoxyalkyl group include linear or branched alkoxyalkyl groups having 2 to 20 (preferably 2 to 10, more preferably 2 to 6, and even more preferably 2 to 4) carbon atoms, such as methoxymethyl, ethoxymethyl, 1-methoxyethyl, 2-methoxyethyl, 1-ethoxyethyl, and 2-ethoxyethyl. Further, examples of the substituted or unsubstituted phenyl group include phenyl groups optionally substituted with 1 to 2 groups selected from hydroxyl groups, halogen atoms, lower alkoxy groups, lower alkenyl groups, methylsulfonyloxy groups, substituted or unsubstituted lower alkyl groups, substituted or unsubstituted amino groups, substituted or unsubstituted phenyl groups, substituted or unsubstituted phenoxy groups, and substituted or unsubstituted pyridyl groups.

[0110] Examples of the quaternary phosphonium cation include quaternary phosphonium cations such as tetramethylphosphonium, tetraethylphosphonium, tetrabutylphosphonium, tetrahexylphosphonium, tetraoctylphosphonium, triethylmethylphosphonium, and tributylethylphosphonium.

[0111] ・Anionic ingredients

[0112] Examples of anion components in the ionic liquid of the present disclosure include halogen anions, pseudohalogen anions, carboxylic acid anions, phosphate anions, amino acid anions, phenolates, pyrimidine oleate, tetrafluoroborate ions (BF 4- ), methanesulfonate ion (CH3SO3 - ), methylphosphonate, sulfate ion and PF6 - wait.

[0113] The halogen anions are not particularly limited, and examples thereof include fluoride ions (F - ), chloride ion (Cl - ), iodide ion (I - ), bromide ion (Br - )wait.

[0114] The pseudohalogen anion is not particularly limited, and examples thereof include cyanide anion, thiocyanate anion, cyanate anion, fulminate anion, and azide anion.

[0115] The carboxylic acid anion is not particularly limited, and examples thereof include monocarboxylic acid anions or dicarboxylic acid anions having 1 to 18 carbon atoms. Examples of carboxylic acid anions include formate anions, acetate anions, propionate anions, butyrate anions, valerate anions, fumarate anions, oxalate anions, lactate anions, and pyruvate anions. It should be noted that the anion component of the ionic liquid preferably includes carboxylic acid anions (OAc) in order to enable easy and efficient recovery of the ionic liquid. - ).

[0116] The phosphoric acid anion is not particularly limited, and examples thereof include phosphoric acid anions and phosphoric acid ester anions having 1 to 40 carbon atoms. Examples of the phosphoric acid ester anions include methyl phosphoric acid monoester anion, octyl phosphoric acid monoester anion, octyl phosphoric acid diester anion, lauryl phosphoric acid monoester anion, lauryl phosphoric acid diester anion, stearyl phosphoric acid monoester anion, stearyl phosphoric acid diester anion, eicosyl phosphoric acid monoester anion, eicosyl phosphoric acid diester anion, and the like.

[0117] As each of the above-mentioned ionic liquids, commercial products may be used, or they may be produced by a known technique.

[0118] The above-mentioned ionic liquid is any combination of the above-mentioned cationic component and the above-mentioned anionic component. For example, an ionic liquid containing an imidazolium cation or a quaternary ammonium cation as a cationic component is preferred. In particular, in terms of the relationship between affinity and separation efficiency in the extraction operation, it is believed that the imidazolium cation is preferred due to the skeleton of formula (1). In addition, an ionic liquid containing a carboxylic acid anion as an anionic component is preferred. More specifically, it is more preferred to be at least one selected from the group consisting of 1-ethyl-3-methylimidazolium acetate (EmimOAc), 1-ethyl-2,3-dimethylimidazolium acetate (EDmimOAc), 1-butyl-3-methylimidazolium acetate, 1-hexyl-3-methylimidazolium acetate and tetrabutylammonium acetate. Furthermore, the ionic liquid is more preferably at least one selected from the group consisting of 1-ethyl-3-methylimidazolium acetate (EmimOAc) and 1-ethyl-2,3-dimethylimidazolium acetate (EDmimOAc), and particularly preferably 1-ethyl-3-methylimidazolium acetate (EmimOAc).

[0119] [Organic acid]

[0120] Next, the organic acid is described. The organic acid is a component separated from the ionic liquid by the above-mentioned extraction operation.

[0121] Examples of the organic acid include carboxylic acids such as formic acid, acetic acid, propionic acid, and trifluoroacetic acid (preferably C 1-18 Carboxylic acid, more preferably C 1-10Carboxylic acid, more preferably C 1-6 Carboxylic acid, particularly preferably C 2-4 In addition, the carboxylic acid is also preferably C 9-18 Carboxylic acid, preferably C 1-7 Carboxylic acid. The above organic acids may be used alone or in combination of two or more.

[0122] The organic acid may also be an organic acid derived from the esterifying agent. In this case, the esterifying agent may include, for example, an acid anhydride. For example, when the esterifying agent used in esterifying the polysaccharide is an acid anhydride, the obtained mixed solution (B2) may contain an acid anhydride and / or an organic acid derived from the acid anhydride. The method disclosed herein may be preferably used to recover an ionic liquid from the mixed solution (B2).

[0123] When the organic acid is a carboxylic acid, C 1-6 The content of the carboxylic acid is, for example, preferably 70% by weight or more, more preferably 80% by weight or more, further preferably 90% by weight or more, further preferably 95% by weight or more, and particularly preferably 99% by weight or more. 1-6 The upper limit of the content of the carboxylic acid relative to the total amount of the carboxylic acid is preferably, for example, 100% by weight.

[0124] The molar ratio of the ionic liquid to the organic acid contained in the mixed solution (A) (ionic liquid: organic acid) is not particularly limited, but is preferably 1:100 to 100:1, more preferably 10:90 to 90:10, further preferably 20:80 to 80:20, and particularly preferably 30:70 to 70:30. By making the ratio of the ionic liquid to the organic acid contained in the mixed solution within the above range, there is a tendency to be able to simply and efficiently recover the ionic liquid from the mixed solution. It should be noted that when the mixed solution (A) is prepared by adding the above-mentioned solvent to the mixed solution (B), the molar ratio of the ionic liquid to the organic acid contained in the mixed solution (B) is also preferably within the above range.

[0125] [water]

[0126] Next, water will be described. Water may be already contained in the mixed solution (B), may be newly added to the mixed solution (B), or may be already contained in the mixed solution (B) and further added to the mixed solution (B). Water forms the aqueous phase in the mixed solution (A) by contacting with an organic solvent (excluding an organic acid) described later.

[0127] The water used in the present disclosure is not particularly limited, and for example, industrial water, tap water, ion-exchanged water, purified water, distilled water, etc. can be used.

[0128] The amount of water used in the method of the present disclosure is not particularly limited. For example, it is preferably 0.01 mol or more, more preferably 0.1 mol or more, more preferably 1 mol or more, more preferably 5 mol or more, more preferably 10 mol or more, more preferably 15 mol or more, more preferably 20 mol or more, and more preferably 25 mol or more. In addition, the amount of water, for example, is preferably 1000 mol or less, more preferably 500 mol or less, more preferably 300 mol or less, more preferably 250 mol or less, more preferably 200 mol or less, more preferably 150 mol or less, more preferably 100 mol or less, more preferably 75 mol or less, more preferably 50 mol or less, and more preferably 40 mol or less. In addition, the amount of water is preferably 0.01 to 1000 mol, more preferably 0.1 to 500 mol, more preferably 1 to 300 mol, and preferably 25 to 40 mol relative to 1 mol of the ionic liquid. When the amount of water contained in the mixed solution (A) is within the above range, the ratio of the ionic liquid contained in the aqueous phase becomes high, and as a result, there is a tendency that the ionic liquid can be easily and efficiently recovered from the mixed solution (A) and / or the mixed solution (B).

[0129] [Organic solvents (excluding organic acids) [Organic solvents (Or)]]

[0130] Next, the organic solvent (excluding organic acids) is described. Here, in this specification, the above-mentioned organic solvent is sometimes referred to as "organic solvent (Or)". The organic solvent (Or) may be already contained in the mixed liquid (B), may be newly added to the mixed liquid (B), or may be already contained in the mixed liquid (B) and further added to the mixed liquid (B). The organic solvent (Or) forms the oil phase in the mixed liquid (A) by contacting with the above-mentioned water.

[0131] The organic solvent (Or) is not particularly limited as long as it is a solvent other than the above-mentioned organic acid and forms an oil phase (organic solvent phase) when mixed with water, and examples thereof include at least one selected from the group consisting of ethers, ketones, esters, aryls, alkanes, and cycloalkanes. The organic solvent (Or) may be used alone or in combination of two or more.

[0132] The ethers are not particularly limited, and examples thereof include dialkyl ethers such as diethyl ether, diisopropyl ether, and methyl tert-butyl ether, and dioxane. The ketones are not particularly limited, and examples thereof include methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and acetophenone. The esters are not particularly limited, and examples thereof include methyl acetate, ethyl acetate, butyl acetate, and isopropyl acetate. The aryls are not particularly limited, and examples thereof include benzene, toluene, xylene, methoxybenzene, and ethylbenzene. The alkanes are not particularly limited, and examples thereof include n-hexane and n-heptane. The cycloalkanes are not particularly limited, and examples thereof include cyclohexane.

[0133] As the above-mentioned organic solvent (Or), from the viewpoint of being able to simply and efficiently recover the ionic liquid from the mixed solution (A), it is preferably at least one selected from the group consisting of ethers, ketones and esters, more preferably at least one selected from the group consisting of ethers (particularly dialkyl ethers) and esters, further preferably at least one selected from the group consisting of diethyl ether, diisopropyl ether and ethyl acetate, and particularly preferably ethyl acetate.

[0134] In the method disclosed herein, the amount of the organic solvent (Or) is not particularly limited, and is preferably, for example, 1 part by weight or more, more preferably 10 parts by weight or more, further preferably 20 parts by weight or more, further preferably 30 parts by weight or more, and further preferably 50 parts by weight or more, relative to 100 parts by weight of the total amount of the ionic liquid, the organic acid, and the water contained in the mixed solution (A). In addition, the amount of the organic solvent (Or) is not particularly limited, and is preferably, for example, 10,000 parts by weight or less, more preferably 6,000 parts by weight or less, further preferably 5,000 parts by weight or less, further preferably 4,000 parts by weight or less, and further preferably 2,000 parts by weight or less, relative to 100 parts by weight of the total amount of the ionic liquid, the organic acid, and the water contained in the mixed solution (A). The upper and lower limits of the amount of the organic solvent (Or) are preferably 1 to 10,000 parts by weight, more preferably 10 to 6,000 parts by weight, further preferably 20 to 5,000 parts by weight, further preferably 30 to 4,000 parts by weight, and further preferably 50 to 2,000 parts by weight, relative to 100 parts by weight of the total amount of the ionic liquid, the organic acid, and the water contained in the mixed solution (A). By setting the amount of the organic solvent (Or) contained in the mixed solution (A) within the above range, the ratio of the organic acid contained in the oil phase becomes high, and as a result, there is a tendency that the ionic liquid can be recovered from the mixed solution (A) simply and efficiently.

[0135] [Other solvents [Solvent (T)]]

[0136] In the method disclosed herein, the mixed solution (A) may contain a solvent in addition to an ionic liquid, an organic acid, water and an organic solvent (Or). Hereinafter, such a solvent will be referred to as "other solvents" and also referred to as "solvent (T)". The above-mentioned solvent (T) may already be contained in the mixed solution (B), may be newly added to the mixed solution (B), or may already be contained in the mixed solution (B) and further added to the mixed solution (B). That is, in the case where the mixed solution (A) contains the solvent (T), the process of containing the solvent (T) may be any of the above. In the case where the mixed solution (B) already contains the above-mentioned solvent (T) from the beginning, the solvent (T) may be contained as the solvent (S). That is, in the case where the mixed solution (B) is a mixed solution (B1), the solvent (S) directly becomes the solvent (T) when the mixed solution (A) is obtained.

[0137] Specific examples of the solvent (T) include the solvents described as the "solvent other than the ionic liquid [solvent (S)]" that may be contained in the mixed liquid (B).

[0138] Among the above-mentioned solvents (T), from the viewpoint of compatibility with ionic liquids and the solubility of esters of polysaccharides, it is preferred to select at least one of the group consisting of sulfoxides, sulfones, amides and lactams. Among them, when separating organic acids, by using at least one selected from the group consisting of dimethyl sulfoxide (DMSO), sulfolane, N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP), there is a tendency that the distribution ratio of the ionic liquid on the aqueous phase side becomes higher. This tendency becomes more significant by using at least one selected from the group consisting of N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP), and becomes more significant by using N-methyl-2-pyrrolidone (NMP).

[0139] The content of the above-mentioned solvent (T) contained in the mixed solution (A) is not particularly limited, and is, for example, preferably 0.01% by mass or more, more preferably 0.05% by weight or more, further preferably 0.1% by weight or more, further preferably 0.3% by weight or more, and particularly preferably 0.5% by weight or more. In addition, the content of the above-mentioned solvent (T) contained in the mixed solution (A) is not particularly limited, and is, for example, preferably 30% by weight or less, more preferably 20% by weight or less, further preferably 10% by weight or less, further preferably 5% by weight or less, and particularly preferably 4% by weight or less. It should be noted that, when the above-mentioned solvent (T) is added to the mixed solution (B), it is preferably prepared in such a way that the obtained mixed solution (A) is within the above-mentioned range.

[0140] The content of the solvent (T) contained in the mixed solution (A) is not particularly limited, and is, for example, preferably 1% by weight or more, more preferably 3% by weight or more, further preferably 5% by weight or more, further preferably 10% by weight or more, and particularly preferably 15% by weight or more. In addition, the content of the solvent (T) contained in the mixed solution (B) is not particularly limited, and is, for example, preferably 90% by weight or less, and more preferably 80% by weight or less.

[0141] [Composition, composition for extraction]

[0142] This embodiment includes a composition containing a water-soluble ionic liquid, an organic acid, water, and an organic solvent (but excluding the organic acid). The above composition may further contain other solvents. According to the composition, a high-purity ionic liquid can be obtained by extraction. The composition in this embodiment is preferably used for extraction. Below, it is described as a composition for extraction.

[0143] Preferred embodiments of the water-soluble ionic liquid contained in the above-mentioned extraction composition are the same as the preferred embodiments described in the above-mentioned [Ionic liquid]. Preferred embodiments of the organic acid contained in the above-mentioned extraction composition are the same as the preferred embodiments described in the above-mentioned [Organic acid]. Preferred embodiments of the water contained in the above-mentioned extraction composition are the same as the preferred embodiments described in the above-mentioned [Water]. Preferred embodiments of the organic solvent (excluding organic acid) contained in the above-mentioned extraction composition are the same as the preferred embodiments described in the above-mentioned [Organic solvent (excluding organic acid) [Organic solvent (Or)]]. Preferred embodiments of other solvents contained in the above-mentioned extraction composition are the same as the preferred embodiments described in the above-mentioned [Other solvents [Solvent (T)]]. Preferred extraction conditions for the above-mentioned extraction composition are the same as the preferred embodiments described in the above-mentioned [Extraction]. In particular, the above-mentioned mixed liquid (A) can be replaced with the extraction composition, and the types, amounts, extraction conditions, etc. of preferred components can be referred to respectively. The extraction composition is obtained by mixing water and / or the above-mentioned organic solvent (Or) in a mixed solution (B) containing an ionic liquid and an organic acid. Therefore, with regard to the types, amounts, distillation conditions, etc. of the preferred components of the extraction composition, reference can be made not only to the mixed solution (A) but also to the mixed solution (B).

[0144] The ionic liquid of the extraction composition is preferably at least one selected from the group consisting of 1-ethyl-3-methylimidazolium acetate (EmimOAc) and 1-ethyl-2,3-dimethylimidazolium acetate (EDmimOAc), and more preferably 1-ethyl-3-methylimidazolium acetate (EmimOAc). The organic acid of the extraction composition is preferably acetic acid.

[0145] The organic solvent of the extraction composition is preferably at least one selected from the group consisting of ethers, ketones, and esters, and more preferably at least one selected from the group consisting of ethers (particularly dialkyl ethers) and esters.

[0146] The above-mentioned other solvent is preferably at least one selected from the group consisting of dimethyl sulfoxide, N,N-dimethylformamide and N-methyl-2-pyrrolidone, more preferably at least one selected from the group consisting of N,N-dimethylformamide and N-methyl-2-pyrrolidone, and particularly preferably N-methyl-2-pyrrolidone.

[0147] Each configuration and combination thereof in the above-mentioned embodiments are examples, and addition, omission, substitution, and other changes of configurations may be appropriately made without departing from the gist of the present disclosure. The present disclosure is not limited to the embodiments but only to the claims.

[0148] Example

[0149] Hereinafter, the present disclosure will be described in more detail by way of examples, but the present disclosure is not limited to these examples.

[0150] The specifications of the NMR apparatus used in the examples are as follows.

[0151] Product name: JNM-ECZ600R.

[0152] Manufacturer: JEOL Ltd.

[0153] [Example 1]

[0154] 0.73 g of EmimOAc and 0.27 g of acetic acid were mixed, and 0.79 g of water was added to prepare a mixed solution. The molar ratio of EmimOAc: acetic acid: water in the mixed solution was 1:1:10. Furthermore, 10 times the weight of ethyl acetate was added to the mixed solution and stirred. After standing at room temperature for 1 hour, 1 ml of each sample was taken from the aqueous phase and the ethyl acetate phase, and the weight of the components was quantified by NMR. The following results were obtained.

[0155] Distribution ratio of acetic acid (acetic acid concentration in ethyl acetate / acetic acid concentration in water) = 0.115

[0156] Distribution ratio of EmimOAc (EmimOAc concentration in ethyl acetate / EmimOAc concentration in water) = 0.00132

[0157] [Example 2]

[0158] 0.73 g of EmimOAc and 0.26 g of acetic acid were mixed, and 1.57 g of water was added to prepare a mixed solution. The EmimOAc: acetic acid: water (molar ratio) in the mixed solution was 1:1:20. Furthermore, 10 times the weight of ethyl acetate was added to the mixed solution and stirred. After standing at room temperature for 1 hour, 1 ml of each sample was taken from the water phase and the ethyl acetate phase, and the weight of the components was quantified by NMR. The following results were obtained.

[0159] Distribution ratio of acetic acid (acetic acid concentration in ethyl acetate / acetic acid concentration in water) = 0.318

[0160] Distribution ratio of EmimOAc (EmimOAc concentration in ethyl acetate / EmimOAc concentration in water) = 0.00117

[0161] [Example 3]

[0162] 0.73 g of EmimOAc and 0.27 g of acetic acid were mixed, and 2.39 g of water was added to prepare a mixed solution. The EmimOAc: acetic acid: water (molar ratio) in the mixed solution was 1:1:30. Furthermore, 10 times the weight of ethyl acetate was added to the mixed solution and stirred. After standing at room temperature for 1 hour, 1 ml of each sample was taken from the water phase and the ethyl acetate phase, and the weight of the components was quantified by NMR. The following results were obtained.

[0163] Distribution ratio of acetic acid = 0.369

[0164] Distribution ratio of EmimOAc = 0.00096

[0165] [Example 4]

[0166] 0.73 g of EmimOAc and 0.27 g of acetic acid were mixed, and 7.86 g of water was added to prepare a mixed solution. The EmimOAc: acetic acid: water (molar ratio) in the mixed solution was 1:1:100. Furthermore, 10 times the weight of ethyl acetate of the mixed solution was added and stirred. After standing at room temperature for 1 hour, 1 ml of each sample was taken from the water phase and the ethyl acetate phase, and the weight of the components was quantified by NMR. The following results were obtained.

[0167] Distribution ratio of acetic acid (acetic acid concentration in ethyl acetate / acetic acid concentration in water) = 0.427

[0168] The distribution ratio of EmimOAc (EmimOAc concentration in ethyl acetate) was not detected.

[0169] [Example 5]

[0170] 0.73 g of EmimOAc and 0.27 g of acetic acid were mixed, and 2.40 g of water was added to prepare a mixed solution. The EmimOAc: acetic acid: water (molar ratio) in the mixed solution was 1:1:30. Furthermore, 10 times the weight of diethyl ether was added to the mixed solution and stirred. After standing at room temperature for 1 hour, 1 ml of each sample was taken from the water phase and the diethyl ether phase, and the weight of the components was quantified by NMR. The following results were obtained.

[0171] Distribution ratio of acetic acid (acetic acid concentration in diethyl ether / acetic acid concentration in water) = 0.561

[0172] Distribution ratio of EmimOAc (EmimOAc concentration in diethyl ether / EmimOAc concentration in water) = 0.00335

[0173] [Example 6]

[0174] 0.73 g of EmimOAc and 0.27 g of acetic acid were mixed, and 2.40 g of water was added to prepare a mixed solution. The EmimOAc: acetic acid: water (molar ratio) in the mixed solution was 1:1:30. Furthermore, 10 times the weight of diisopropyl ether of the mixed solution was added and stirred. After standing at room temperature for 1 hour, 1 ml of each sample was taken from the water phase and the diisopropyl ether phase, and the weight of the components was quantified by NMR. The following results were obtained.

[0175] Distribution ratio of acetic acid (acetic acid concentration in diisopropyl ether / acetic acid concentration in water) = 0.172

[0176] Distribution ratio of EmimOAc (EmimOAc concentration in diisopropyl ether / EmimOAc concentration in water) = 0.00883

[0177] [Example 7]

[0178] 0.73 g of EmimOAc and 0.27 g of acetic acid were mixed, and 3.86 g of water was added to prepare a mixed solution. The molar ratio of EmimOAc: acetic acid: water in the mixed solution was 1:1:50. Furthermore, 10 times the weight of ethyl acetate was added to the mixed solution and stirred. After standing at room temperature for 1 hour, 1 ml of each sample was taken from the aqueous phase and the ethyl acetate phase, and the weight of the components was quantified by NMR. The following results were obtained.

[0179] Distribution ratio of acetic acid (acetic acid concentration in ethyl acetate / acetic acid concentration in water) = 0.401

[0180] Distribution ratio of EmimOAc (EmimOAc concentration in ethyl acetate / EmimOAc concentration in water) = 0.000935

[0181] [Example 8]

[0182] 0.73 g of EmimOAc and 0.27 g of acetic acid were mixed, and 1.57 g of water and 0.43 g of NMP were added to prepare a mixed solution. The molar ratio of EmimOAc: acetic acid: water: NMP in the mixed solution was 1:1:20:1. Furthermore, 10 times the weight of ethyl acetate was added to the mixed solution and stirred. After standing at room temperature for 1 hour, 1 ml of each sample was taken from the water phase and the ethyl acetate phase, and the weight of the components was quantified by NMR. The following results were obtained.

[0183] Distribution ratio of acetic acid (acetic acid concentration in ethyl acetate / acetic acid concentration in water) = 0.286

[0184] Distribution ratio of EmimOAc (EmimOAc concentration in ethyl acetate / EmimOAc concentration in water) = 0.000990

[0185] NMP distribution ratio (NMP concentration in ethyl acetate / NMP concentration in water) = 0.386

[0186] Therefore, it has been demonstrated that when water and an organic solvent (e.g., ethyl acetate) are added to a mixed solution containing an ionic liquid (e.g., EmimOAc) and an organic acid (e.g., acetic acid) and the organic acid is separated by extraction, if it is desired to distribute the ionic liquid closer to the aqueous phase, it is preferred to further add an organic solvent such as NMP.

[0187] [Example 9]

[0188] The structural formula of EmimOAc recovered from the aqueous phase of Example 3 is the same as the structural formula of EmimOAc before extraction (before recovery).

[0189] [Example 10]

[0190] After evaporating water from the mixed solution of EmimOAc and water recovered in Example 3, cellulose (0.18 g (trade name "Avicel PH-101" of Sigma-Aldrich, number average degree of polymerization 105) was mixed with the obtained EmimOAc (1 g) and stirred, and the cellulose dissolved. This phenomenon proves that the ionic liquid recovered by the method of the present disclosure can be reused.

[0191] [Comparative Example 1]

[0192] 0.75 g of EmimOAc and 0.27 g of acetic acid were mixed to prepare a mixed solution. The molar ratio of EmimOAc to acetic acid in the mixed solution was 1:1. Furthermore, ethyl acetate was added in an amount 10 times the weight of the mixed solution and stirred, resulting in separation into two phases, an ethyl acetate phase (upper phase) and an acetic acid phase (lower phase). After standing at room temperature for 1 hour, 1 ml of the sample was taken and the weight of the components was quantified by NMR. As a result, it was found that the ethyl acetate phase contained 46.3 wt% of EmimOAc and 51.6 wt% of acetic acid. In addition, it was found that the acetic acid phase contained 53.7 wt% of EmimOAc.

[0193] In summary, the configuration and variations of the present invention are described below.

[0194] [1] A method for recovering an ionic liquid, characterized in that it is a method for recovering the ionic liquid from a mixed solution (B) containing the ionic liquid and an organic acid, wherein the ionic liquid is water-soluble; at least one selected from the group consisting of water and an organic solvent (excluding the organic acid) (also referred to as an organic solvent (Or)) is added to the mixed solution (B), and the organic acid is separated by extraction.

[0195] [2] The method for recovering an ionic liquid according to [1], wherein the mixed liquid (B) is a mixed liquid (B1) containing a reaction product obtained when a specific raw material is esterified with an esterifying agent using an ionic liquid as a solvent.

[0196] [3] The method for recovering an ionic liquid according to [2], wherein the raw material is a polysaccharide (for example, one or more selected from the group consisting of cellulose, hemicellulose, xylan, mannan, glucomannan, glucuronoxylan, starch, amylose, amylopectin, glycogen, dextrin, pectin, chitin, chitosan, agarose, carrageenan, isolichenan, laminaran, lichenin, glucan, inulin, levan, fructan, galactan, arabinan, pentosan, alginic acid, pectic acid, protuberic acid, colominic acid, porphyran, fucoidan, ascosan, locust bean gum, guar gum, tamarind gum, tara gum, and gum arabic).

[0197] [4] The method for recovering an ionic liquid according to [2] or [3], wherein the esterification agent is one or more selected from the group consisting of chain ester compounds, cyclic ester compounds, unsaturated aldehydes, saturated aldehydes, acid halides, acid anhydrides and allyl alcohol.

[0198] [5] The method for recovering an ionic liquid according to [4], wherein the acid anhydride is one or more selected from the group consisting of acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, caproic anhydride, heptanoic anhydride, octanoic anhydride, nonanoic anhydride, capric anhydride, lauric anhydride, myristic anhydride, palmitic anhydride, stearic anhydride, oleic anhydride, linoleic anhydride, linolenic anhydride, benzoic anhydride, phthalic anhydride, maleic anhydride and succinic anhydride.

[0199] [6] The method for recovering an ionic liquid according to any one of [1] to [5], wherein the mixed liquid (B) contains a solvent other than the ionic liquid (solvent (S)).

[0200] [7] The method for recovering an ionic liquid according to [6], wherein the solvent (S) is selected from nitriles such as acetonitrile, sulfoxides such as dimethyl sulfoxide (DMSO), sulfones such as cyclic sulfones (e.g., sulfolane), ethers such as cyclic ethers (e.g., 1,3-dioxolane, 1,4-dioxane, tetrahydrofuran), amides such as N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMAc), lactams such as N-methyl-2-pyrrolidone (NMP), lactones such as γ-butyrolactone, and At least one selected from the group consisting of amines such as pyridine; at least one selected from the group consisting of sulfoxides, sulfones, amides and lactams; at least one selected from the group consisting of dimethyl sulfoxide (DMSO), sulfolane, N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP); at least one selected from the group consisting of N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP); or N-methyl-2-pyrrolidone (NMP).

[0201] [8] The method for recovering an ionic liquid according to any one of [1] to [7], wherein the method for preparing a mixed solution (A) comprising an ionic liquid, an organic acid, water and an organic solvent (Or) by adding at least one selected from the group consisting of water and an organic solvent (Or) to the mixed solution (B) is as follows: a method for preparing by adding the above-mentioned organic solvent (Or) to a mixed solution (B) comprising an ionic liquid, an organic acid and water; a method for preparing by adding water and the above-mentioned organic solvent (Or) to a mixed solution (B) comprising an ionic liquid, an organic acid and water; a method for preparing by adding water to a mixed solution (B) comprising an ionic liquid, an organic acid and the above-mentioned organic solvent (Or); A method for preparing by adding water and the above-mentioned organic solvent (Or) to a mixed solution (B) comprising an ionic liquid, an organic acid and the above-mentioned organic solvent (Or); a method for preparing by adding water and the above-mentioned organic solvent (Or) to a mixed solution (B) comprising an ionic liquid and an organic acid; a method for preparing by adding water to a mixed solution comprising an ionic liquid, an organic acid, water and the above-mentioned organic solvent (Or); a method for preparing by adding the above-mentioned organic solvent (Or) to a mixed solution comprising an ionic liquid, an organic acid, water and the above-mentioned organic solvent (Or); or a method for preparing by adding water and the above-mentioned organic solvent (Or) to a mixed solution comprising an ionic liquid, an organic acid, water and the above-mentioned organic solvent (Or).

[0202] [9] The method for recovering an ionic liquid according to any one of [1] to [8], wherein the mixed liquid (B) is subjected to an extraction operation without pretreatment.

[0203]

[10] The method for recovering an ionic liquid according to any one of [1] to [9], wherein the structural formula of the recovered ionic liquid is the same as the structural formula of the ionic liquid in the mixed solution (B) before extraction.

[0204]

[11] The method for recovering an ionic liquid according to any one of [1] to

[10] , wherein the temperature during extraction of the mixed solution (B) is 0°C to 100°C, 1°C to 90°C, 3°C to 80°C, or 5°C to 70°C.

[0205]

[12] The method for recovering an ionic liquid according to any one of [1] to

[11] , wherein the pressure during extraction of the mixed liquid (B) is 10 hPa to 2000 hPa, 100 hPa to 1500 hPa, or 500 hPa to 1200 hPa (e.g., normal pressure).

[0206]

[13] The method for recovering an ionic liquid according to any one of [1] to

[12] , wherein the ionic liquid is a salt composed of a cationic component and an anionic component.

[0207]

[14] The method for recovering an ionic liquid according to any one of [1] to

[13] , wherein the ionic liquid contains at least one selected from the group consisting of imidazolium cations, pyridinium cations, pyrrolidinium cations, piperidinium cations, quaternary ammonium cations and quaternary phosphonium cations as a cationic component.

[0208]

[15] The method for recovering an ionic liquid according to any one of [1] to

[14] , wherein the ionic liquid contains an imidazolium cation or a quaternary ammonium cation as a cationic component.

[0209]

[16] The method for recovering an ionic liquid according to

[14] or

[15] , wherein the imidazolium cation is of the formula (1) (wherein R 1 and R 3 are the same or different and are substituted or unsubstituted alkyl, alkenyl, alkoxyalkyl, or substituted or unsubstituted phenyl, R 2 , R 4 and R 5 The cation is the same or different and is a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an alkoxyalkyl group, or a substituted or unsubstituted phenyl group).

[0210]

[17] The method for recovering an ionic liquid according to any one of

[14] to

[16] , wherein the pyridinium cation is of the formula (2) (wherein R 6 is an alkyl group, an alkenyl group, an alkoxyalkyl group, or a substituted or unsubstituted phenyl group, R 7 ~R 11 The cation is the same or different and is a hydrogen atom, an alkyl group, an alkenyl group, an alkoxyalkyl group, or a substituted or unsubstituted phenyl group).

[0211]

[18] The method for recovering an ionic liquid according to any one of

[14] to

[17] , wherein the pyrrolidinium cation is the above-mentioned formula (3) (wherein R 12 and R 13 are the same or different and are alkyl, alkenyl, alkoxyalkyl, or substituted or unsubstituted phenyl, R 14 ~R 21 The cation is the same or different and is a hydrogen atom, an alkyl group, an alkenyl group, an alkoxyalkyl group, or a substituted or unsubstituted phenyl group).

[0212]

[19] The method for recovering an ionic liquid according to any one of

[14] to

[18] , wherein the piperidinium cation is the above-mentioned formula (4) (wherein R 22 and R 23 are the same or different and are alkyl, alkenyl, alkoxyalkyl, or substituted or unsubstituted phenyl, R 24 ~R 33The cation is the same or different and is a hydrogen atom, an alkyl group, an alkenyl group, an alkoxyalkyl group, or a substituted or unsubstituted phenyl group).

[0213]

[20] The method for recovering an ionic liquid according to any one of

[14] to

[19] , wherein the quaternary ammonium cation is the above-mentioned formula (5) (wherein R 34 ~R 37 The ammonium cation represented by (i) is the same or different and is an alkyl group, an alkenyl group, an alkoxyalkyl group, or a substituted or unsubstituted phenyl group).

[0214]

[21] The method for recovering an ionic liquid according to any one of

[14] to

[20] , wherein the quaternary phosphonium cation is the above-mentioned formula (6) (wherein R 38 ~R 41 The phosphonium cation represented by (i) is the same or different and is an alkyl group, an alkenyl group, an alkoxyalkyl group, or a substituted or unsubstituted phenyl group).

[0215]

[22] The method for recovering an ionic liquid according to any one of [1] to

[21] , wherein the ionic liquid comprises an anion selected from the group consisting of halogen anions, pseudohalogen anions, carboxylic acid anions, phosphate anions, amino acid anions, phenolates, pyrimidine oleates, tetrafluoroborate ions (BF 4- ), methanesulfonate ion (CH3SO3 - ), methylphosphonate, sulfate ion and PF6 - At least one of the constituted group serves as an anion component.

[0216]

[23] The method for recovering an ionic liquid according to any one of [1] to

[22] , wherein the ionic liquid contains a carboxylate anion as an anion component.

[0217]

[24] The method for recovering an ionic liquid according to any one of [1] to

[23] , wherein the organic acid is a carboxylic acid, a C 1-18 Carboxylic acid, C 1-10 Carboxylic acid, C 1-6 Carboxylic acid, C 2-4 Carboxylic acid, C 9-18 Carboxylic acid and / or C 1-7 carboxylic acid.

[0218]

[25] The method for recovering an ionic liquid according to any one of [1] to

[24] , wherein the organic acid is at least one selected from the group consisting of formic acid, acetic acid, propionic acid, and trifluoroacetic acid.

[0219]

[26] The method for recovering an ionic liquid according to any one of [1] to

[25] , wherein the organic acid is a carboxylic acid, and relative to the total amount of the carboxylic acid, C 1-6The content of the carboxylic acid is 70% by weight or more, 80% by weight or more, 90% by weight or more, 95% by weight or more, or 99% by weight or more.

[0220]

[27] The method for recovering an ionic liquid according to any one of [1] to

[26] , wherein the molar ratio of the ionic liquid to the organic acid contained in the mixed solution (A) or the mixed solution (B) (ionic liquid: organic acid) is 1:100 to 100:1, 10:90 to 90:10, 20:80 to 80:20 or 30:70 to 70:30.

[0221]

[28] The method for recovering an ionic liquid according to any one of [1] to

[27] , wherein the amount of water used or the amount of water contained in the mixed solution (A) is 0.01 mol or more, 0.1 mol or more, 1 mol or more, 5 mol or more, 10 mol or more, 15 mol or more, 20 mol or more, 25 mol or more, 1000 mol or less, 500 mol or less, 300 mol or less, 250 mol or less, 200 mol or less, 150 mol or less, 100 mol or less, 75 mol or less, 50 mol or less, 40 mol or less, 0.01 to 1000 mol, 0.1 to 500 mol, 1 to 300 mol, and / or 25 to 40 mol relative to 1 mol of the ionic liquid.

[0222]

[29] The method for recovering an ionic liquid according to any one of [1] to

[28] , wherein the organic solvent (Or) is at least one selected from the group consisting of ethers, ketones, esters, aromatics, alkanes and cycloalkanes.

[0223]

[30] The method for recovering an ionic liquid according to any one of [1] to

[29] , wherein the organic solvent (Or) is at least one selected from the group consisting of ethers, ketones, and esters.

[0224]

[31] The method for recovering an ionic liquid according to any one of [1] to

[30] , wherein the organic solvent (Or) is an ether (particularly a dialkyl ether) or an ester.

[0225]

[32] The method for recovering an ionic liquid according to any one of [1] to

[31] , wherein the ether is at least one selected from the group consisting of dialkyl ethers (diethyl ether, diisopropyl ether or methyl tert-butyl ether) and dioxane; the ketone is at least one selected from the group consisting of methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and acetophenone; the ester is at least one selected from the group consisting of methyl acetate, ethyl acetate, butyl acetate and isopropyl acetate; the aromatics are at least one selected from the group consisting of benzene, toluene, xylene, methoxybenzene and ethylbenzene; the alkane is at least one selected from the group consisting of n-hexane and n-heptane; and / or the cycloalkane is cyclohexane.

[0226]

[33] The method for recovering an ionic liquid according to any one of [8] to

[32] , wherein the amount of the organic solvent (Or) is 1 part by weight or more, 10 parts by weight or more, 20 parts by weight or more, 30 parts by weight or more, 50 parts by weight or more, 10,000 parts by weight or less, 6,000 parts by weight or less, 5,000 parts by weight or less, 4,000 parts by weight or less, 2,000 parts by weight or less, 1 to 10,000 parts by weight, 10 to 6,000 parts by weight, 20 to 5,000 parts by weight, 30 to 4,000 parts by weight and / or 50 to 2,000 parts by weight, based on 100 parts by weight of the total amount of the ionic liquid, the organic acid and water contained in the mixed liquid (A).

[0227]

[34] The method for recovering an ionic liquid according to any one of [8] to

[33] , wherein the mixed liquid (A) further contains a solvent (solvent (T)) in addition to the ionic liquid, the organic acid, water and the organic solvent (Or).

[0228]

[35] The method for recovering an ionic liquid according to

[34] , wherein the solvent (T) is at least one selected from the group consisting of sulfoxides, sulfones, amides and lactams.

[0229]

[36] The method for recovering an ionic liquid according to

[34] or

[35] , wherein the solvent (T) is at least one selected from the group consisting of dimethyl sulfoxide (DMSO), sulfolane, N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP), at least one selected from the group consisting of N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP), or is N-methyl-2-pyrrolidone (NMP).

[0230]

[37] The method for recovering an ionic liquid according to any one of

[34] to

[36] , wherein the content of the above-mentioned solvent (T) contained in the mixed liquid (A) is 0.01 weight % or more, 0.05 weight % or more, 0.1 weight % or more, 0.3 weight % or more, 0.5 weight % or more, 30 weight % or less, 20 weight % or less, 10 weight % or less, 5 weight % or less and / or 4 weight % or less.

[0231]

[38] The method for recovering an ionic liquid according to any one of

[34] to

[37] , wherein the content of the above-mentioned solvent (T) contained in the mixed liquid (B) is 1 weight % or more, 3 weight % or more, 5 weight % or more, 10 weight % or more, 15 weight % or more, 90 weight % or less and / or 80 weight % or less.

[0232]

[39] The method for recovering an ionic liquid according to any one of [1] to

[38] , wherein the organic acid is C 1-7 of carboxylic acid.

[0233]

[40] A composition comprising a water-soluble ionic liquid, an organic acid, water and an organic solvent (but excluding the organic acid).

[0234]

[41] The composition according to

[40] , which is for extraction.

[0235]

[42] The composition according to

[40] or

[41] , wherein the ionic liquid of the composition is at least one selected from the group consisting of 1-ethyl-3-methylimidazolium acetate (EmimOAc) and 1-ethyl-2,3-dimethylimidazolium acetate (EDmimOAc), or is 1-ethyl-3-methylimidazolium acetate (EmimOAc).

[0236]

[43] The composition according to any one of

[40] to

[42] , wherein the organic acid in the composition is acetic acid.

[0237]

[44] The composition according to any one of

[40] to

[43] , wherein the organic solvent of the composition is at least one selected from the group consisting of ethers, ketones and esters, or is at least one selected from the group consisting of ethers (particularly dialkyl ethers) and esters.

[0238]

[45] The composition according to any one of

[40] to

[44] , further comprising at least one selected from the group consisting of dimethyl sulfoxide, N,N-dimethylformamide and N-methyl-2-pyrrolidone, at least one selected from the group consisting of N,N-dimethylformamide and N-methyl-2-pyrrolidone, or N-methyl-2-pyrrolidone.

[0239] Industrial Applicability

[0240] According to the method for recovering an ionic liquid of the present disclosure, the ionic liquid can be recovered simply and efficiently from a mixed solution containing an ionic liquid and an organic acid.

Claims

1. A method for recovering an ionic liquid, characterized in that: A method for recovering an ionic liquid from a mixed solution containing an ionic liquid and an organic acid, wherein: The ionic liquid is water-soluble, At least one selected from the group consisting of water and an organic solvent other than an organic acid is added to the mixed liquid, and the organic acid is separated by extraction.

2. The method for recovering an ionic liquid according to claim 1, wherein: The ionic liquid contains an imidazolium cation or a quaternary ammonium cation as a cationic component.

3. The method for recovering an ionic liquid according to claim 1 or 2, wherein: The ionic liquid contains carboxylate anions as anion components.

4. The method for recovering an ionic liquid according to any one of claims 1 to 3, wherein: The organic acid is a carboxylic acid.

5. The method for recovering an ionic liquid according to any one of claims 1 to 4, wherein: The organic solvent is at least one selected from the group consisting of ethers, ketones, esters, aromatics, alkanes, and cycloalkanes.

6. The method for recovering an ionic liquid according to any one of claims 1 to 5, wherein: The organic solvent is at least one selected from the group consisting of ethers, ketones, and esters.

7. The method for recovering an ionic liquid according to any one of claims 1 to 6, wherein: The organic acid is C 1-7 of carboxylic acid.

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