Method for producing onium salt and method for purifying onium salt

Abstract

The present invention provides a process for preparing an onium salt free of carboxylic acids or having a carboxylic acid content reduced to a degree to which cellulose is sufficiently soluble in the onium salt. The method for obtaining an onium salt from a mixture containing an onium salt and a carboxylic acid comprises the following steps (1), (2) and (3): step (1) obtaining a mixture containing an onium salt and a carboxylic acid, step (2) adding an amine to the mixture containing an onium salt and a carboxylic acid to form an amine-carboxylate salt formed from the amine and the carboxylic acid, and step (3) adding an amine to the mixture containing an amine and a carboxylic acid to form an amine-carboxylate salt formed from the amine and the carboxylic acid. The onium salt is separated from the amine-carboxylate produced in step (1) to obtain the onium salt.

Description

Technical Field

[0001] The present invention relates to a method for preparing an onium salt and a method for purifying the onium salt. Background Art

[0002] Polysaccharides are substances composed of many monosaccharide molecules polymerized through glycosidic bonds. Among polysaccharides, cellulose, which is composed of β-glucose molecules, is the most abundant biomass resource on earth and is widely studied as an environmentally friendly material for its properties such as solubility and moldability. However, cellulose is difficult to dissolve in common solvents due to strong hydrogen bonds between or within molecular chains.

[0003] Onium salts have been proposed as solvents for dissolving cellulose. PTL 1 discloses a method for dissolving cellulose by using a molten ionic liquid composed of a 1-alkyl-3-methyl-imidazolium cation and an acetate anion.

[0004] PTL 2 discloses a method for preparing a quaternary ammonium organic acid salt by preparing a quaternary ammonium carbonate, mixing the prepared quaternary ammonium carbonate with an organic acid, and subjecting the organic acid to anion exchange. PTL 2 discloses a method for preparing a quaternary ammonium carbonate from a nitrogen-containing heteroaromatic compound such as N-methylimidazole or N-methylbenzimidazole (starting material), mixing it with acetic acid (organic acid), and subjecting the organic acid to anion exchange to prepare a quaternary ammonium organic acid salt.

[0005] PTL 3 discloses a method for generating a quaternary ammonium carboxylate by reacting a quaternary ammonium alkyl carbonate with a carboxylic acid. In an embodiment, PTL 3 discloses that N,N-diethyl-N-(2-methoxyethyl)-N-methylammonium=methyl carbonate is reacted with methoxyacetic acid to obtain N,N-diethyl-N-(2-methoxyethyl)-N-methylammonium=methoxyacetate.

[0006] NPL 1 discloses 1,3-dialkylimidazolium acetate (when R 1 and R 2 The same) and 1-alkyl-3-methylimidazolium acetate, 1,3-dialkylimidazolium acetate and 1,3-dimethylimidazolium acetate (when R 1 is methyl, and R 1 and R 2 NPL 1 also discloses that colored impurities can be removed by passing an ionic liquid (such as imidazolium acetate) through a decolorizing carbon column.

[0007]

[0008] NPL 2 discloses a method for separating acetic acid from a synthetic mixture containing ionic liquid 1-ethyl-3-methylimidazolium acetate. The separation method includes a method of evaporating acetic acid as a volatile component from a mixture containing 1-ethyl-3-methylimidazolium acetate, a method of extracting acetic acid with a solvent immiscible with 1-ethyl-3-methylimidazolium acetate, and a method of adding methanol to a mixture containing 1-ethyl-3-methylimidazolium acetate to esterify acetic acid and then distilling off methyl acetate.

[0009] Reference List

[0010] Patent Literature

[0011] PTL 1: JP2005-506401A

[0012] PTL 2: JPS63-280045A

[0013] PTL 3: JP2015-83545A

[0014] Non-patent literature

[0015] NPL 1: Pure Appl.Chem.,Vol.84,No.3,pp.745-754,2012

[0016] NPL 2: J.Chem.Eng.Data,2013,58,197-202 Summary of the invention

[0017] Technical issues

[0018] In the preparation method of quaternary ammonium carboxylates (an ionic liquid and also an onium salt) described in the prior art documents, the carboxylic acid used remains in the quaternary ammonium carboxylates (product). The remaining carboxylic acid forms an association complex with the prepared quaternary ammonium carboxylates. The use of quaternary ammonium carboxylates containing an association complex in dissolving cellulose results in low solubility of cellulose in the quaternary ammonium carboxylates.

[0019] In view of the current state of the prior art, an object of the present invention is to provide a method for preparing an onium salt that does not contain carboxylic acid or an onium salt whose carboxylic acid content is reduced to such an extent that cellulose has sufficient solubility in the onium salt. Another object of the present invention is to provide a method for purifying an onium salt, comprising removing carboxylic acid contained in the onium salt or reducing the carboxylic acid content to such an extent that cellulose has sufficient solubility in the onium salt.

[0020] Solution

[0021] The present inventors have conducted extensive studies on a method for preparing an onium salt containing no carboxylic acid or an onium salt having a carboxylic acid content reduced to such an extent that cellulose has sufficient solubility in the onium salt, and a method for purifying the onium salt, and have completed the present invention.

[0022] Specifically, the present invention provides the following [1] to

[10] . [1]

[0024] A method for preparing an onium salt represented by the following formula (1):

[0025] Formula (1)

[0026]

[0027] in,

[0028] R 3 , R 4 and R 5 may be the same or different and each represents a hydrogen atom or a C 1 -C 4 Hydrocarbon,

[0029] R 1 and R 2 may be the same or different and each represents a hydrocarbon group optionally containing at least one heteroatom,

[0030] R 1 and R 2 may contain branched chains and / or cyclic structures and / or double bonds,

[0031] R 1 , R 2 , R 3 , R 4 and R 5 Some or all of R 1 , R 2 , R 3 , R 4 and R 5 The bound nitrogen atoms and / or carbon atoms together may form a ring structure, and

[0032] R 6 represents a hydrocarbon group which optionally contains at least one heteroatom and may contain a double bond and / or a cyclic structure and / or a branched structure,

[0033] The method comprises the following steps (1), (2) and (3):

[0034] Step (1), obtaining a mixture containing an onium salt represented by formula (1) and a carboxylic acid represented by the following formula (3), wherein the mixture is obtained according to the reaction route represented by the following formula (2):

[0035] Formula (2)

[0036]

[0037] Formula (3)

[0038]

[0039] Where R 6 represents a hydrocarbon group which optionally contains at least one heteroatom and may contain a double bond and / or a cyclic structure and / or a branched structure,

[0040] step (2), adding an amine to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3) obtained in step (1) to generate an amine-carboxylate formed by the amine and the carboxylic acid represented by formula (3); and

[0041] Step (3) is to separate the onium salt represented by formula (1) from the amine-carboxylate produced in step (2) to obtain the onium salt represented by formula (1). [2]

[0043] The method for preparing an onium salt according to [1], wherein the amine added in step (2) is an amine represented by the following formula (4):

[0044] Formula (4)

[0045]

[0046] in,

[0047] R 7 , R 8 and R 9 may be the same or different and each represents a hydrogen atom or a C 1 -C 18 Hydrocarbon,

[0048] The C 1 -C 18 The hydrocarbon group may contain a double bond, and may contain a branched structure and / or a cyclic structure, and

[0049] R 7 , R 8 and R 9 The total number of carbon atoms contained in each is 8 or greater. [3]

[0051] The method for producing an onium salt according to [1], wherein the onium salt represented by formula (1) is of at least two types. [4]

[0053] The method for producing an onium salt according to [1], wherein the mixture containing the onium salt represented by the formula (1) and the carboxylic acid represented by the formula (3) further contains water and / or a hydrophilic solvent. [5]

[0055] The method for preparing an onium salt according to [1], wherein the amine added in step (2) is an amine solution prepared by diluting the amine with a solvent. [6]

[0057] A method for purifying an onium salt represented by the following formula (1), comprising removing the carboxylic acid represented by the following formula (3) from a mixture containing the onium salt represented by the following formula (1) and the carboxylic acid represented by the following formula (3),

[0058] Formula (1)

[0059]

[0060] in,

[0061] R 3 , R 4 and R 5 may be the same or different and each represents a hydrogen atom or a C 1 -C 4 Hydrocarbon,

[0062] R 1 and R 2 may be the same or different and each represents a hydrocarbon group optionally containing at least one heteroatom,

[0063] R 1 and R 2 may contain branched chains and / or cyclic structures and / or double bonds,

[0064] R 1 , R 2 , R 3 , R 4 and R 5 Some or all of R 1 , R 2 , R 3 , R 4 and R 5 The bound nitrogen atoms and / or carbon atoms together may form a ring structure, and

[0065] R 6 represents a hydrocarbon group which optionally contains at least one heteroatom and may contain a double bond and / or a cyclic structure and / or a branched structure,

[0066] The method comprises the following steps (1), (2) and (3):

[0067] Step (1), obtaining a mixture containing an onium salt represented by formula (1) and a carboxylic acid represented by formula (3), wherein the mixture is obtained according to the reaction route represented by the following formula (2):

[0068] Formula (2)

[0069]

[0070] Formula (3)

[0071]

[0072] Where R 6 represents a hydrocarbon group which optionally contains at least one heteroatom and may contain a double bond and / or a cyclic structure and / or a branched structure,

[0073] step (2), adding an amine to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3) obtained in step (1) to generate an amine-carboxylate formed by the amine and the carboxylic acid represented by formula (3); and

[0074] Step (3) is to separate the onium salt represented by formula (1) from the amine-carboxylate produced in step (2) to obtain the onium salt represented by formula (1). [7]

[0076] The method for purifying an onium salt according to [6], wherein the amine added in step (2) is an amine represented by the following formula (4):

[0077] Formula (4)

[0078]

[0079] in,

[0080] R 7 , R 8 and R 9 may be the same or different and each represents a hydrogen atom or a C 1 -C 18 Hydrocarbon,

[0081] The C 1 -C 18 The hydrocarbon group may contain a double bond, and may contain a branched structure and / or a cyclic structure, and

[0082] R 7 , R 8 and R 9 The total number of carbon atoms contained in each is 8 or greater. [8]

[0084] The method for purifying an onium salt according to [6], wherein the onium salt represented by formula (1) is of at least two types. [9]

[0086] The method for purifying an onium salt according to [6], wherein the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3) further contains water and / or a hydrophilic solvent.

[10]

[0088] The method for purifying an onium salt according to [6], wherein the amine added in step (2) is an amine solution prepared by diluting the amine with a solvent.

[0089] Beneficial effects of the present invention

[0090] The present invention provides a method for preparing an onium salt containing no carboxylic acid or an onium salt having a carboxylic acid content reduced to a level that cellulose has sufficient solubility in the onium salt. The present invention also provides a method for purifying an onium salt, comprising removing carboxylic acid contained in the onium salt or reducing the carboxylic acid content to a level that cellulose has sufficient solubility in the onium salt. DETAILED DESCRIPTION

[0091] The present invention is described in detail below. One embodiment of the present invention relates to a method for preparing an onium salt represented by the following formula (1):

[0092] Formula (1)

[0093]

[0094] in,

[0095] R 3 , R 4 and R 5 may be the same or different and each represents a hydrogen atom or a C 1 -C 4 Hydrocarbon,

[0096] R 1 and R 2 may be the same or different and each represents a hydrocarbon group optionally containing at least one heteroatom,

[0097] R 1 and R 2 may contain branched chains and / or cyclic structures and / or double bonds,

[0098] R 1 , R 2 , R 3 , R 4 and R 5 Some or all of R 1 , R 2 , R 3 , R 4 and R 5The bound nitrogen atoms and / or carbon atoms together may form a ring structure, and

[0099] R 6 represents a hydrocarbon group which optionally contains at least one heteroatom and may contain a double bond and / or a cyclic structure and / or a branched structure,

[0100] The method comprises the following steps (1), (2) and (3):

[0101] Step (1), obtaining a mixture containing an onium salt represented by formula (1) and a carboxylic acid represented by the following formula (3), wherein the mixture is obtained according to the reaction route represented by the following formula (2):

[0102] Formula (2)

[0103]

[0104] Formula (3)

[0105]

[0106] Where R 6 represents a hydrocarbon group which optionally contains at least one heteroatom and may contain a double bond and / or a cyclic structure and / or a branched structure,

[0107] step (2), adding an amine to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3) obtained in step (1) to generate an amine-carboxylate formed by the amine and the carboxylic acid represented by formula (3); and

[0108] Step (3) is to separate the onium salt represented by formula (1) from the amine-carboxylate produced in step (2) to obtain the onium salt represented by formula (1).

[0109] The onium salt represented by the following formula (1) is an imidazolium carboxylate containing an imidazolium cation and a carboxylate anion.

[0110] Formula (1):

[0111]

[0112] in,

[0113] R 3 , R 4 and R 5 may be the same or different and each represents a hydrogen atom or a C 1 -C 4 Hydrocarbon,

[0114] R 1 and R 2 may be the same or different and each represents a hydrocarbon group optionally containing at least one heteroatom,

[0115] R 1 and R 2 may contain branched chains and / or cyclic structures and / or double bonds,

[0116] R 1 , R 2 , R 3 , R 4 and R 5 Some or all of R 1 , R 2 , R 3 , R 4 and R 5 The bound nitrogen atoms and / or carbon atoms together may form a ring structure, and

[0117] R 6 It represents a hydrocarbon group which may optionally contain at least one heteroatom and may contain a double bond and / or a cyclic structure and / or a branched structure.

[0118] In the formula (1), the imidazolium cation represented by the following formula (1-1) is described.

[0119] Formula (1-1):

[0120]

[0121] in,

[0122] R 3 , R 4 and R 5 may be the same or different and each represents a hydrogen atom or a C 1 -C 4 Hydrocarbon,

[0123] R 1 and R 2 may be the same or different and each represents a hydrocarbon group optionally containing at least one heteroatom,

[0124] R 1 and R 2 may contain branches and / or ring structures and / or double bonds, and

[0125] R 1 , R 2 , R 3 , R 4 and R 5 Some or all of R 1 , R 2 , R 3 , R 4 and R 5The bound nitrogen atoms and / or carbon atoms together may form a ring structure.

[0126] In formula (1-1), R 1 and R 2 Each represents a hydrocarbon group optionally containing at least one heteroatom. The "hydrocarbon group optionally containing at least one heteroatom" may be linear, and may contain a branched chain and / or a cyclic structure and / or a double bond. 1 and R 2 The hydrocarbon group represented may not contain heteroatoms.

[0127] In formula (1-1), when R 1 and R 2 When at least one of the groups is a hydrocarbon group containing no heteroatoms, the number of carbon atoms is preferably 1 to 12, more preferably 1 to 8, and further preferably 1 to 3. 1 and R 2 When each is a hydrocarbon group containing a heteroatom, the number of carbon atoms is preferably 2 to 12, more preferably 2 to 8, and further preferably 2 to 4.

[0128] In formula (1-1), when R 1 and R 2 When each contains at least one hetero atom, the number of hetero atoms is preferably 1 to 5, more preferably 1 or 2. The number of carbon atoms in the hydrocarbon group is 2 or more, preferably 2 to 12, more preferably 2 to 8, and even more preferably 2 to 4.

[0129] In formula (1-1), when R 1 and R 2 When each is a hydrocarbon group containing at least one hetero atom, examples of the hetero atom include a nitrogen atom, an oxygen atom and a sulfur atom. The number of the hetero atoms is preferably 1 to 5, more preferably 1 or 2.

[0130] In formula (1-1), R 1 and R 2 A hydrocarbon group containing at least one heteroatom refers to a hydrocarbon group formed by replacing (i) a bond between two adjacent carbon atoms and / or (ii) a hydrogen atom of a -CH2- group (methylene) with a hydrogen atom of another -CH2- group (methylene) in a hydrocarbon group containing no heteroatoms by the following structures: such as -O-, -N<, -NH-, -S-, -C(=O)-O-, -C(=O)-, =N-, -C(=O)-N<, -C(=O)-NH-, -OC(=O)-O-, -OC(=O)-N<, -OC(=O)-NH-, -C(=O)-N[-C(=O)-]-, -C(=O)-NH-C(=O)-, >NC(=O)-N<, >NC(=O)-NH-, -HN-C(=O)-NH-, -S(=O)-, -S(=O)-2 -、-S(=O) 2 -O-, -OS(=O) 2 -O-, >NC(=S)-N<, >NC(=S)-NH-, -HN-C(=S)-NH-, -C(=N-)-, or -C(=NH)-. The number and combination of substitutions of these structures are not particularly limited; however, R 1 and R 2 The number of heteroatoms in is preferably 1 to 5, more preferably 1 or 2.

[0131] Preferably, the heteroatom-containing hydrocarbon group is (i) a bond between two adjacent carbon atoms and / or (ii) a -CH 2 - group (methylene) and another -CH 2 A hydrocarbon group formed by replacing a hydrogen atom of a -(methylene group) with -O- or -S-, more preferably with -O-.

[0132] In the present invention, (i) a bond between two adjacent carbon atoms and / or (ii) a -CH 2 -(methylene) hydrogen atom and another -CH 2 The structure in which the hydrogen atom of -(methylene) is replaced by -O- or -S- may be not only an ether structure or a thioether structure but also an epoxy structure or a thioepoxy structure, for example, an epoxy group, a thioepoxy group, a glycidyl ether group or an epoxycyclohexyl group. In this case, R 1 and R 2 It may be, for example, an epoxy group or a thioepoxy group.

[0133] When R 1 and R 2 When two or more -O- and / or -S- structures are contained, the number of carbon atoms between the -O- and / or -S- structures is preferably two or more.

[0134] In formula (1-1), R 1 and R 2 Examples of hydrocarbon groups optionally containing at least one heteroatom represented by the invention include straight or branched alkyl groups optionally containing at least one heteroatom, straight or branched alkenyl groups optionally containing at least one heteroatom, straight or branched alkynyl groups optionally containing at least one heteroatom, cycloalkyl groups optionally branched and optionally containing at least one heteroatom, cycloalkenyl groups optionally branched and optionally containing at least one heteroatom, aryl groups optionally branched and optionally containing at least one heteroatom, and aralkyl groups optionally branched and optionally containing at least one heteroatom. Preferably, straight or branched alkyl groups optionally containing at least one heteroatom, straight or branched alkenyl groups optionally containing at least one heteroatom, and cycloalkyl groups optionally branched and optionally containing at least one heteroatom are used.

[0135] The “straight or branched chain alkyl group optionally containing at least one hetero atom” is preferably a straight or branched chain C 1 -C 12 In another embodiment, the linear or branched alkyl group optionally containing at least one heteroatom is preferably a linear or branched C 1 -C 12 Alkyl, more preferably a straight chain or branched C 1 -C 8 Alkyl, more preferably a straight chain or branched C 1 -C 4 In another embodiment, the linear or branched alkyl group optionally containing at least one heteroatom is preferably a linear or branched C 1 -C 12 Alkyl, more preferably a straight chain or branched C 1 -C 8 Alkyl, more preferably a straight chain or branched C 1 -C 3 alkyl.

[0136] The “straight or branched alkenyl group optionally containing at least one hetero atom” is preferably a straight or branched C 2 -C 12 In another embodiment, the straight chain or branched alkenyl group optionally containing at least one heteroatom is preferably a straight chain or branched C 2 -C 12 Alkenyl, more preferably a straight chain or branched C 2 -C 8 Alkenyl, further preferably a straight chain or branched C 2 -C 4 In another embodiment, the straight chain or branched alkenyl group optionally containing at least one heteroatom is preferably a straight chain or branched C 2 -C 12 Alkenyl, more preferably a straight chain or branched C 2 -C 8 Alkenyl, more preferably a straight chain or branched C 2 -C 3 Alkenyl.

[0137] The "cycloalkyl group which is optionally branched and optionally contains at least one heteroatom" is preferably a C cycloalkyl group which is optionally branched and optionally contains 1 to 5 heteroatoms. 3 -C 12In another embodiment, the cycloalkyl group which is optionally branched and optionally contains at least one heteroatom is preferably a C cycloalkyl group which is optionally branched and optionally contains 1 or 2 heteroatoms. 3 -C 12 Cycloalkyl, more preferably C optionally branched and optionally containing 1 or 2 heteroatoms 3 -C 8 Cycloalkyl, more preferably C optionally branched and optionally containing 1 or 2 heteroatoms 3 -C 4 In another embodiment, the optionally branched and optionally heteroatom-containing cycloalkyl is preferably an optionally branched C 3 -C 12 Cycloalkyl, more preferably optionally branched C 3 -C 8 The cycloalkyl group is preferably C 3 Cycloalkyl.

[0138] In formula (1-1), R 1 and R 2 The specific examples of the heteroatom-free hydrocarbon radicals include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, octyl, 2-ethylhexyl, decyl, dodecyl, vinyl, ethynyl, propenyl, isopropenyl, allyl, propargyl, butenyl, crotyl, butadienyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyl, adamantyl, phenyl, benzyl, tolyl, styryl, 2,4,6-trimethylphenyl. The heteroatom-free hydrocarbon radicals are preferably methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl, and hexyl, more preferably methyl, ethyl, propyl, isopropyl, and tert-butyl.

[0139] In formula (1-1), R 1 and R 2 The "heteroatom-containing hydrocarbon group" represented is preferably 3-indolyl, p-methoxyphenyl, 7-oxabicyclo[2,2,1]-hept-5-en-2-yl, 1,2-epoxyethyl, 1-methyl-2-methoxyvinyl, 2-furanyl, 2-pyridyl, 4-imidazolyl, or benzyloxymethyl, more preferably 1-methyl-2-methoxyvinyl or 2-furanyl, but the present invention is not limited to these groups.

[0140] In formula (1-1), R 3 , R 4 and R 5 It is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

[0141] In formula (1-1), R 1, R 2 , R 3 , R 4 and R 5 Some or all of R 1 , R 2 , R 3 , R 4 and R 5 The nitrogen atom and / or carbon atom bonded together may form a ring structure. Specific examples of the ring structure are, but not limited to, R 1 and R 3 , R 3 and R 2 , R 2 and R 5 , R 5 and R 4 , or R 1 and R 4 bonded together and with C containing 2 to 10 heteroatoms 2 -C 24 The hydrocarbons are cross-linked to form a ring structure.

[0142] In formula (1-1), specific examples of the imidazolium having a hydrocarbon group containing no heteroatoms include 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1-methyl-3-propylimidazolium, 1-butyl-3-methylimidazolium, 1-methyl-3-pentylimidazolium, 1-hexyl-3-methylimidazolium, 1-heptyl-3-methylimidazolium, 1-methyl-3-octylimidazolium, 1-methyl-3-nonylimidazolium, 1-decyl-3-methylimidazolium, 1-allyl-3-methylimidazolium, and 1-allyl-3-ethylimidazolium. The imidazolium having a hydrocarbon group containing no hetero atom is preferably 1,3-dimethylimidazolium, 1-ethyl-3-methylimidazolium, 1,3-diethylimidazolium, and 1-butyl-3-methylimidazolium, but the present invention is not limited to these compounds.

[0143] In formula (1-1), specific examples of the imidazolium having a hydrocarbon group containing a heteroatom include 1,3-bis(2-methoxyethyl)imidazolium, 1,3-bis(2-ethoxyethyl)imidazolium, 1,3-bis(2-propoxyethyl)imidazolium, 1,3-bis(2-isopropoxyethyl)imidazolium, 1,3-bis(2-phenoxyethyl)imidazolium, 1,3-bis(2-benzyloxyethyl)imidazolium, 1,3-bis[2-(p-methoxybenzyloxy)ethyl]imidazolium, 1,3-bis[2-(2-methoxyethoxymethoxy)ethyl]imidazolium, 1,3-bis[2-(2-benzyloxyethoxy)ethyl]imidazolium, 1,3-bis(3-methoxypropyl)imidazolium, 1,3-bis(3-ethoxypropyl)imidazolium, Imidazolium, 1,3-bis(3-propoxypropyl)imidazolium, 1,3-bis(3-isopropoxypropyl)imidazolium, 1,3-bis(3-allyloxypropyl)imidazolium, 1,3-bis(3-butoxypropyl)imidazolium, 1,3-bis[3-(1-methylpropoxy)propyl]imidazolium, 1,3-bis[3-(2-methylpropoxy)propyl]imidazolium imidazolium, 1,3-bis[3-(1,1-dimethylethoxy)propyl]imidazolium, 1,3-bis[(oxolan-2-yl)methyl]imidazolium, 1,3-bis(3-pentyloxypropyl)imidazolium, 1,3-bis(3-neopentyloxypropyl)imidazolium, 1,3-bis(3-hexyloxypropyl)imidazolium, 1,3-bis(3-cyclohexyloxypropyl)imidazolium , 1,3-bis(3-heptyloxypropyl)imidazolium, 1,3-bis(3-octyloxypropyl)imidazolium, 1,3-bis(3-nonyloxypropyl)imidazolium, 1,3-bis{3-[(2-ethylhexyl-1-yl)oxy]propyl}imidazolium, 1,3-bis[3-(2,4,6-trimethylphenoxy)propyl]imidazolium, 1,3-bis[3-(2 -methoxyethoxy)propyl]imidazolium, 1,3-bis[2-(dimethylamino)ethyl]imidazolium, 1,3-bis[3-(dimethylamino)propyl]imidazolium, 1,3-bis(2-methylthioethyl)imidazolium, 1,3-bis{2-[(furan-2-yl)methylthio]ethyl]imidazolium, 1,3-bis[2-(furan-2-yl)methyl]imidazolium imidazolium, 1,3-bis[1-(methoxymethyl)propyl]imidazolium, 1,3-bis(4-methoxybutyl)imidazolium, 1,3-bis(4-ethoxybutyl)imidazolium, 1,3-bis(4-propoxybutyl)imidazolium, 1,3-bis(4-isopropoxybutyl)imidazolium, 1,3-bis(4-allyloxybutyl)imidazolium, 1,3-bis(4 1,3-bis[4-(1-methylpropoxy)butyl]imidazolium, 1,3-bis[4-(2-methylpropoxy)butyl]imidazolium, 1,3-bis[4-(1,1-dimethylethoxy)butyl]imidazolium, 1,3-bis(4-pentyloxybutyl)imidazolium, 1,3-bis(4-neopentyloxybutyl)imidazolium, 1,3-bis(4-hexyloxybutyl)imidazolium, 1,3-bis(4-cyclohexyloxybutyl)imidazolium, 1,3-bis(4-heptyloxybutyl)imidazolium, 1,3-bis(4-octyloxybutyl)imidazolium, 1,3-bis{4-[(2-ethylhexyl-1-yl)oxy]butyl}imidazolium, 1,3-bis(5-methoxypentyl)imidazolium, 1,3-bis (5-ethoxypentyl) imidazolium, 1,3-bis(5-propoxypentyl) imidazolium, 1,3-bis(5-isopropoxypentyl) imidazolium, 1,3-bis(5-allyloxypentyl) imidazolium, 1,3-bis(5-butoxypentyl) imidazolium, 1,3-bis[5-(1-methylpropoxy)pentyl] imidazolium, 1,3-bis[5-(2-methylpropoxy)pentyl] imidazolium imidazolium, 1,3-bis[5-(1,1-dimethylethoxy)pentyl]imidazolium, 1,3-bis(5-pentyloxypentyl)imidazolium, 1,3-bis(5-neopentyloxypentyl)imidazolium, 1,3-bis(5-hexyloxypentyl)imidazolium, 1,3-bis(5-cyclohexyloxypentyl)imidazolium, 1,3-bis(5-heptyloxypentyl) Imidazolium, 1,3-bis(6-methoxyhexyl)imidazolium, 1,3-bis(6-ethoxyhexyl)imidazolium, 1,3-bis(6-propoxyhexyl)imidazolium, 1,3-bis(6-isopropoxyhexyl)imidazolium, 1,3-bis(6-allyloxyhexyl)imidazolium, 1,3-bis(6-butoxyhexyl)imidazolium, 1,3-bis[6-(1- 1,3-bis[6-(2-methylpropoxy)hexyl]imidazolium, 1,3-bis[6-(1,1-dimethylethoxy)hexyl]imidazolium, 1,3-bis(6-pentyloxyhexyl)imidazolium, 1,3-bis(6-neopentyloxyhexyl)imidazolium, 1,3-bis(6-hexyloxyhexyl)imidazolium, 1,3-bis( 6-cyclohexyloxyhexyl)imidazolium, 1,3-bis[(2-methoxycyclohex-1-yl)methyl]imidazolium, 1,3-bis[(2-ethoxycyclohex-1-yl)methyl]imidazolium, 1,3-bis[(2-propoxycyclohex-1-yl)methyl]imidazolium, 1,3-bis[(2-isopropoxycyclohex-1-yl)methyl]imidazolium, 1,3-bis[( 2-Butoxycyclohex-1-yl)methyl]imidazolium, 1,3-bis{[2-(1-methylpropoxy)cyclohex-1-yl]methyl}imidazolium, 1,3-bis{[2-(2-methylpropoxy)cyclohex-1-yl]methyl}imidazolium, 1,3-bis{[2-(1,1-dimethylethoxy)cyclohex-1-yl]methyl}imidazolium, 1,3-bis[( 1,3-bis[(2-neopentyloxycyclohexyl-1-yl)methyl]imidazolium, 1,3-bis[(2-neopentyloxycyclohexyl-1-yl)methyl]imidazolium, 1,3-bis(3-methylthiopropyl)imidazolium, 1,3-bis[2-(methylsulfonyl)ethyl]imidazolium, 1,3-bis[(thiophen-2-yl)methyl]imidazolium, 1,3-bis(p-methoxyphenyl)imidazolium, 1,3-bis(p-ethoxyphenyl)imidazolium, 1,3-bis(3,4-methylenedioxyphenyl)imidazolium, 1,3-bis(3,4-methylenedioxybenzyl)imidazolium, 1,3-bis{(7-oxabicyclo[2,2,1]hept-2-yl)methyl}imidazolium, 1-methoxypropyl-3-methylthiopropylimidazolium, 1,3-bis(3-methoxypropyl)-2-methylimidazolium, and 1,3-bis(2-methoxyethyl)-2-methylimidazolium. The imidazolium having a hydrocarbon group containing a heteroatom is preferably 1,3-bis(3-methoxypropyl)imidazolium, 1,3-bis(3-ethoxypropyl)imidazolium, 1,3-bis(3-propoxypropyl)imidazolium, 1,3-bis(3-isopropoxypropyl)imidazolium, 1,3-bis(3-allyloxypropyl)imidazolium, 1,3-bis(3-butoxypropyl)imidazolium, 1,3-bis[3-(1-methylpropoxy)propyl]imidazolium, 1,3-bis[3-(2-methylpropoxy)propyl]imidazolium, 1,3-bis[3-(1,1-dimethylethoxy)propyl]imidazolium, 1,3-bis[(oxolan-2-yl)methyl]imidazolium, 1,3-bis[3-(2-methoxypropyl)imidazolium The present invention is preferably 1,3-bis(3-methoxypropyl)imidazolium, 1,3-bis(3-ethoxypropyl)imidazolium, 1-methoxypropyl-3-methylthiopropylimidazolium, 1,3-bis(3-methoxypropyl)-2-methylimidazolium, or 1,3-bis(2-methoxyethyl)-2-methylimidazolium, more preferably 1,3-bis(3-methoxypropyl)imidazolium, 1,3-bis(3-ethoxypropyl)imidazolium, 1-methoxypropyl-3-methylthiopropylimidazolium, 1,3-bis[3-(2-methoxyethoxy)propyl]imidazolium, 1,3-bis(2-methoxyethyl)-2-methylimidazolium, or 1,3-bis(3-methoxypropyl)-2-methylimidazolium, but the present invention is not limited to these compounds.

[0144] In the formula (1), the carboxylate anion represented by the following formula (1-2) is described.

[0145] Formula (1-2):

[0146]

[0147] Where R 6 It represents a hydrocarbon group which may optionally contain at least one heteroatom and may contain a double bond and / or a cyclic structure and / or a branched structure.

[0148] In formula (1-2), R 6 represents a hydrocarbon group optionally containing at least one heteroatom. The "hydrocarbon group optionally containing at least one heteroatom" may be linear, or may contain a branched chain and / or a cyclic structure and / or a double bond. 6 The hydrocarbon group represented may not contain heteroatoms.

[0149] In formula (1-2), when R 6 When it is a hydrocarbon group containing no heteroatoms, the number of carbon atoms is preferably 1 to 12, more preferably 1 to 8, and further preferably 1 to 3. 6 In the case of a hydrocarbon group containing a heteroatom, the number of carbon atoms is preferably 2 to 12, more preferably 2 to 8, and even more preferably 2 to 4.

[0150] In formula (1-2), when R 6 When at least one hetero atom is contained, the number of hetero atoms is preferably 1 to 5, more preferably 1 or 2. The number of carbon atoms in the hydrocarbon group is 2 or more, preferably 2 to 12, more preferably 2 to 8, and even more preferably 2 to 4.

[0151] When R 6 In the case of a hydrocarbon group containing at least one hetero atom in formula (1-2), examples of the hetero atom include a nitrogen atom, an oxygen atom and a sulfur atom. The number of the hetero atoms is preferably 1 to 5, more preferably 1 or 2.

[0152] In formula (1-2), R 6 The term "hydrocarbon group containing at least one heteroatom" refers to a hydrocarbon group in which, in a hydrocarbon group containing no heteroatoms, (i) the bond between two adjacent carbon atoms and / or (ii) the hydrogen atom of a -CH2- group (methylene) and the hydrogen atom of another -CH2- group (methylene) are replaced by the following structures: such as -O-, -N<, -NH-, -S-, -C(=O)-O-, -C(=O)-, =N-, -C(=O)-N<, -C(=O)-NH-, -OC(=O)-O-, -OC(=O)-N<, -OC(=O)-NH-, -C(=O)-N[-C(=O)-]-, -C(=O)-NH-C(=O)-, >NC(=O)-N<, >NC(=O)-NH-, -HN-C(=O)-NH-, -S(=O)-, -S(=O)- 2 -、-S(=O) 2 -O-, -OS(=O) 2 -O-, >NC(=S)-N<, >NC(=S)-NH-, -HN-C(=S)-NH-, -C(=N-)-, or -C(=NH)-. The number and combination of substitutions of these structures are not particularly limited; however, R 6 The number of heteroatoms in is preferably 1 to 5, more preferably 1 or 2.

[0153] Preferably, the hydrocarbon group containing at least one heteroatom is (i) a bond between two adjacent carbon atoms and / or (ii) a -CH 2 - group (methylene) and another -CH 2- A hydrocarbon group formed by replacing the hydrogen atom of the group (methylene) with -O- or -S-, more preferably -O-.

[0154] In formula (1-2), R 6 In the case of (i) a bond between two adjacent carbon atoms and / or (ii) a -CH 2 -(methylene) hydrogen atom and another -CH 2 The structure in which the hydrogen atom of -(methylene) is replaced by -O- or -S- may be not only an ether structure or a thioether structure but also an epoxy structure or a thioepoxy structure, for example, an epoxy group, a thioepoxy group, a glycidyl ether group or an epoxycyclohexyl group. In this case, R 1 It may be, for example, an epoxy group or a thioepoxy group.

[0155] In formula (1-2), when R 6 When two or more -O- and / or -S- structures are contained, the number of carbon atoms between the -O- and / or -S- structures is preferably two or more.

[0156] In formula (1-2), R 6 The embodiment of the hydrocarbon radical optionally containing at least one heteroatom in the embodiment includes a straight chain or branched chain alkyl radical optionally containing at least one heteroatom, a straight chain or branched chain alkenyl radical optionally containing at least one heteroatom, a straight chain or branched chain alkynyl radical optionally containing at least one heteroatom, a cycloalkyl radical optionally branched and optionally containing at least one heteroatom, a cycloalkenyl radical optionally branched and optionally containing at least one heteroatom, an aryl radical optionally branched and optionally containing at least one heteroatom, and an aralkyl radical optionally branched and optionally containing at least one heteroatom. Preferably, a straight chain or branched chain alkyl radical optionally containing at least one heteroatom, a straight chain or branched chain alkenyl radical optionally containing at least one heteroatom, and a cycloalkyl radical optionally branched and optionally containing at least one heteroatom.

[0157] The “straight or branched chain alkyl group optionally containing at least one hetero atom” is preferably a straight or branched chain C 1 -C 12 In another embodiment, the linear or branched alkyl group optionally containing at least one heteroatom is preferably a linear or branched C 1 -C 12 Alkyl, more preferably a straight chain or branched C 1 -C 8 Alkyl, more preferably a straight chain or branched C 1 -C 4In another embodiment, the linear or branched alkyl group optionally containing at least one heteroatom is preferably a linear or branched C 1 -C 12 Alkyl, more preferably a straight chain or branched C 1 -C 8 Alkyl, more preferably a straight chain or branched C 1 -C 3 alkyl.

[0158] The “straight or branched alkenyl group optionally containing at least one hetero atom” is preferably a straight or branched C 2 -C 12 In another embodiment, the straight chain or branched alkenyl group optionally containing at least one heteroatom is preferably a straight chain or branched C 2 -C 12 Alkenyl, more preferably a straight chain or branched C 2 -C 8 Alkenyl, further preferably a straight chain or branched C 2 -C 4 In another embodiment, the straight chain or branched alkenyl group optionally containing at least one heteroatom is preferably a straight chain or branched C 2 -C 12 Alkenyl, more preferably a straight chain or branched C 2 -C 8 Alkenyl, more preferably a straight chain or branched C 2 -C 3 Alkenyl.

[0159] The "cycloalkyl group which is optionally branched and optionally contains at least one heteroatom" is preferably a C cycloalkyl group which is optionally branched and optionally contains 1 to 5 heteroatoms. 3 -C 12 In another embodiment, the cycloalkyl group which is optionally branched and optionally contains one heteroatom is preferably a C 3 -C 12 Cycloalkyl, more preferably C optionally branched and optionally containing 1 or 2 heteroatoms 3 -C 8 Cycloalkyl, more preferably C optionally branched and optionally containing 1 or 2 heteroatoms 3 -C 4 In another embodiment, the optionally branched and optionally heteroatom-containing cycloalkyl is preferably an optionally branched C 3 -C 12 Cycloalkyl, more preferably optionally branched C3 -C 8 The cycloalkyl group is preferably C 3 Cycloalkyl.

[0160] In formula (1-2), R 6 The specific examples of the heteroatom-free hydrocarbon radicals include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, octyl, 2-ethylhexyl, decyl, dodecyl, vinyl, ethynyl, propenyl, isopropenyl, allyl, propargyl, butenyl, crotyl, butadienyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyl, adamantyl, phenyl, benzyl, tolyl, styryl, 2,4,6-trimethylphenyl. The heteroatom-free hydrocarbon radicals are preferably methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl, and hexyl, more preferably methyl, ethyl, propyl, isopropyl, and tert-butyl.

[0161] In formula (1-2), R 6 The "hydrocarbon group containing at least one heteroatom" is preferably methoxymethyl, methoxyethyl, ethoxymethyl, propoxy, or 2-methoxyethoxy, more preferably methoxymethyl, methoxyethyl, or 2-methoxyethoxy, but the present invention is not limited to these groups.

[0162] In formula (1-2), R 6 Preferred is a methyl group, an ethyl group, a methoxymethyl group or a methoxyethyl group.

[0163] Specific examples of the carboxylate anion represented by formula (1-2) include acetate ion, propionate ion, acrylate ion, propiolate ion, butyrate ion, isobutyrate ion, methacrylate ion, crotonate ion, butynoate ion, cyclopropanecarboxylate ion, valerate ion, isovalerate ion, pivalate ion, angelate ion, tiglate ion, cyclobutanecarboxylate ion, hexanoate ion, cyclopentanecarboxylate ion, heptanoate ion, sorbate ion, cyclohexanecarboxylate ion, benzoate ion, octanoate ion, 2-ethylhexylcarboxylate ion, toluate ion, 2-norbornanecarboxylate ion, nonanoate ion, cinnamate ion, decanoate ion, adamantanecarboxylate ion, geranate ion, undecanoate ion, laurate ion, and naphthylcarboxylate ion. The carboxylate anion is preferably an acetate ion, a propionate ion, an acrylate ion, a propiolate ion, a butylate ion, an isobutyrate ion, a methacrylate ion, a crotonate ion, a butylate ion, a valerate ion, an isovalerate ion, a pivalate ion, a methoxyacetate ion, an ethoxyacetate ion, a propoxyacetate ion, (2-methoxyethoxy)acetate ion, (2-ethoxyethoxy)acetate ion, (2-propoxyethoxy)acetate ion, 3-(2-methoxyethoxy)propionate ion, 3-(2-ethoxyethoxy)propionate ion, 3-(2-propoxyethoxy)propionate ion, 3-(3-methoxypropoxy)propionate ion, 3-(3-ethoxypropoxy)propionate ion, 3-(3-propoxypropoxy)propionate ion ion, 3-[2-(2-methoxyethoxy)ethoxy]propionate ion, 3-[2-(2-ethoxyethoxy)ethoxy]propionate ion, 4,7,10,13-tetraoxatetradecanoate ion, 4,7,10,13-tetraoxapentadecanoate ion, 4,7,10,13,16-pentaoxaheptadecanoate ion, 4,7,10,13,16-pentaoxaoctadecanoate ion, (methylthio)acetate ion, (ethylthio)acetate ion, 3-(methylthio)propionate ion, 3-[(2-methoxyethyl)thio]propionate ion, or 3-[(2-ethoxyethyl)thio]propionate ion, particularly preferably acetate ion, methoxyacetate ion, acrylate ion, or methacrylate ion, but the present invention is not limited to these ions.

[0164] The imidazolium carboxylate represented by formula (1) is preferably an onium salt formed by a combination of a cation selected from 1,3-bis(2-methoxyethyl)imidazolium, 1,3-bis(3-methoxypropyl)imidazolium, 1,3-bis(3-ethoxypropyl)imidazolium, 1,3-bis(3-methylthiopropyl)imidazolium, 1,3-bis[3-(2-methoxyethoxy)propyl]imidazolium, 1-methoxypropyl-3-methylthiopropylimidazolium, 1,3-bis(2-methoxyethyl)-2-methylimidazolium, and 1,3-bis(3-methoxypropyl)-2-methylimidazolium and an anion selected from acetate ion, methoxyacetate ion, acrylate ion, and methacrylate ion.

[0165] More specifically, the onium salt represented by formula (1) includes 1,3-bis(2-methoxyethyl)imidazolium acetate, 1,3-bis(3-methoxypropyl)imidazolium acetate, 1,3-bis(3-methoxypropyl)imidazolium acrylate, 1,3-bis(3-methoxypropyl)imidazolium methacrylate, 1,3-bis(3-ethoxypropyl)imidazolium acetate, 1-methoxypropyl-3-methylthiopropylimidazolium acetate, 1,3-bis(3-methylthiopropyl)imidazolium acetate, 1,3-bis(2-methoxyethyl)-2-methylimidazolium acetate, 1,3-bis(2-methoxyethyl)-2 -methylimidazolium acrylate, 1,3-bis(2-methoxyethyl)-2-methylimidazolium methacrylate, 1,3-bis(3-methoxypropyl)-2-methylimidazolium acetate, 1,3-bis(3-methoxypropyl)-2-methylimidazolium acrylate, 1,3-bis(3-methoxypropyl)-2-methylimidazolium methacrylate, 1,3-bis[3-(2-methoxyethoxy)propyl]imidazolium acetate, 1,3-bis[3-(2-methoxyethoxy)propyl]imidazolium acrylate, and 1,3-bis[3-(2-methoxyethoxy)propyl]imidazolium methacrylate. The onium salt is preferably 1,3-bis(3-methoxypropyl)imidazolium acetate, 1,3-bis(3-methoxypropyl)imidazolium acrylate, or 1,3-bis(3-methoxypropyl)imidazolium methacrylate, but the present invention is not limited to these compounds.

[0166] The present invention relates to a method for preparing an onium salt represented by formula (1), comprising the following steps (1), (2) and (3):

[0167] Step (1), obtaining a mixture containing an onium salt represented by formula (1) and a carboxylic acid represented by the following formula (3), wherein the mixture is obtained according to the reaction route represented by the following formula (2):

[0168] Formula (2)

[0169]

[0170] Formula (3):

[0171]

[0172] Where R 6 represents a hydrocarbon group which optionally contains at least one heteroatom and may contain a double bond and / or a cyclic structure and / or a branched structure,

[0173] step (2), adding an amine to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3) obtained in step (1) to generate an amine-carboxylate formed by the amine and the carboxylic acid represented by formula (3); and

[0174] Step (3) is to separate the onium salt represented by formula (1) from the amine-carboxylate produced in step (2) to obtain the onium salt represented by formula (1).

[0176] Step (1) is a step of obtaining a mixture containing an onium salt represented by formula (1) and a carboxylic acid represented by formula (3) according to the reaction route represented by the following formula (2).

[0177] Formula (2)

[0178]

[0179] R in formula (2) 1 , R 2 , R 3 , R 4 , R 5 , and R 6 Respectively with R in formula (1) 1 , R 2 , R 3 , R 4 , R 5 , and R 6 same.

[0180] The reaction of formula (2) is explained. 1 -NH 2 and / or R 2 -NH 2 Amine compounds represented by R 3 -CHO-represented aldehyde compound, R 4 -C(=O)-C(=O)-R 5 The dicarbonyl compound and R 6 The carboxylic acid represented by -COOH (Formula (3)) is reacted.

[0181] By R 1 -NH 2 or R 2 -NH 2Specific examples of the amine compounds represented by include 2-methoxyethylamine, 2-ethoxyethylamine, 2-propoxyethylamine, 2-isopropoxyethylamine, 2-allyloxyethylamine, 2-butoxyethylamine, 2-(1-methylpropoxy)ethylamine, 2-(2-methylpropoxy)ethylamine, 2-(1,1-dimethylethoxy)ethylamine, 2-pentyloxyethylamine, 2-neopentyloxyethylamine, 2-hexyloxyethylamine, 2-phenoxyethylamine, 2-heptyloxyethylamine, 2-octyloxyethylamine, 2-nonyloxyethylamine, 2-decyloxyethylamine, 2-cyclopentyloxyethylamine, 2-cyclohexyloxyethylamine, 2-(2-ethylhex-1-yl)oxyethylamine, 2-(2,4,6-trimethylphenoxyethylamine, 2-(4-(2-methoxy)ethylamine, 2-(benzyloxy)ethylamine, 2-(p-methoxybenzyloxy)ethylamine, 2-(2-methoxyethoxymethoxy)ethylamine, 2-(2-benzyloxyethoxy)ethylamine, 2-(dimethylamino)ethylamine, 3-methoxypropylamine, 3-ethoxypropylamine, 3-propoxypropylamine, 3-allyloxypropylamine, 3-isopropoxypropylamine, 3-(1-methylpropoxy)propylamine, 3-(2-methylpropoxy)propylamine, 3-(1,1-dimethylethoxy)propylamine, 3-butoxypropylamine, 3-pentyloxypropylamine, 3-neopentyloxypropylamine, 3-hexyloxypropylamine, 3-cyclohexyloxypropylamine, 3-heptyloxypropylamine, 3-octyloxypropylamine, 3-nonyloxypropylamine amine, 3-(2-ethylhexyl-1-yl)oxypropylamine, 3-(2,4,6-trimethylphenoxy)propylamine, 3-(2-methoxyethoxy)propylamine, 3-(dimethylamino)propylamine, 4-methoxybutylamine, 4-ethoxybutylamine, 4-propoxybutylamine, 4-isopropoxybutylamine, 4-allyloxybutylamine, 4-butoxybutylamine, 4-(1-methylpropoxy)butylamine, 4-(2-methylpropoxy)butylamine, 4-(1,1-dimethylethoxy)butylamine, 4-pentyloxybutylamine, 4-neopentyloxybutylamine, 4-hexyloxybutylamine, 4-cyclohexyloxybutylamine, 4-heptyloxybutylamine, 4-octyloxybutylamine, 4-(2-ethylhexyl-1-yl) butylamine, 5-methoxypentylamine, 5-ethoxypentylamine, 5-propoxypentylamine, 5-isopropoxypentylamine, 5-allyloxypentylamine, 5-butoxypentylamine, 5-(1-methylpropoxy)pentylamine, 5-(2-methylpropoxy)pentylamine, 5-(1,1-dimethylethoxy)pentylamine, 5-pentyloxypentylamine, 5-neopentyloxypentylamine, 5-hexyloxypentylamine, 5-cyclohexyloxypentylamine, 5-heptyloxypentylamine, 6-methoxyhexylamine, 6-ethoxyhexylamine, 6-propoxyhexylamine, 6-isopropoxyhexylamine, 6-allyloxyhexylamine, 6-butoxyhexylamine, 6-(1-methylpropoxy)hexylamine, 6-(2-methylpropoxy)hexylamine, 6-(1,1-dimethylethoxy)pentylamine1-dimethylethoxy)hexylamine, 6-pentyloxyhexylamine, 6-neopentyloxyhexylamine, 6-hexyloxyhexylamine, 6-cyclohexyloxyhexylamine, 2-methoxycyclohexyl-1-ylmethylamine, (2-ethoxycyclohexyl-1-yl)methylamine, (2-propoxycyclohexyl-1-yl)methylamine, (2-isopropoxycyclohexyl-1-yl)methylamine, (2-butoxycyclohexyl-1-yl)methylamine, [2-(1-methylpropoxy)cyclohexyl-1-yl]methylamine, [2-(2-methylpropoxy)cyclohexyl-1-yl]methylamine, [2-(1,1-dimethylethoxy)cyclohexyl-1-yl] methylamine, (2-pentyloxycyclohex-1-yl)methylamine, (2-neopentyloxycyclohex-1-yl)methylamine, 2-methylthioethylamine, 3-methylthiopropylamine, 1-(methoxymethyl)propylamine, (oxolan-2-yl)methylamine, (furan-2-yl)methylamine, 2-[(furan-2-yl)methylthio]ethylamine, 2-(methylsulfonyl)ethylamine, (thiophen-2-yl)methylamine, p-methoxyaniline, p-ethoxyaniline, 3,4-methylenedioxyaniline, 3,4-methylenedioxybenzylamine, and (7-oxabicyclo[2,2,1]hept-2-yl)methylamine.

[0182] The amine is preferably 2-methoxyethylamine, 3-methoxypropylamine, 3-ethoxypropylamine, 3-isopropoxypropylamine, 3-butoxypropylamine, 3-(2-methoxyethoxy)propylamine, 3-methylthiopropylamine and 3-(dimethylamino)propylamine, more preferably 2-methoxyethylamine, 3-methoxypropylamine and 3-(2-methoxyethoxy)propylamine, but the present invention is not limited to these amines. 1 -NH 2 The amine compound and R 2 -NH 2 The amine compounds represented may be the same or different.

[0183] R 3 Specific examples of the aldehyde compound represented by -CHO include formaldehyde, acetaldehyde, propionaldehyde, and butyraldehyde. Although the aldehyde compound is preferably formaldehyde or acetaldehyde, the present invention is not limited to these aldehyde compounds. The formaldehyde used may be a cyclic oligomer or polymer capable of generating formaldehyde in the reaction system, such as paraformaldehyde, trioxane, or tetraoxane.

[0184] R 3 The aldehyde compound represented by -CHO may be used in the form of an aqueous solution of the aldehyde compound or an alcohol (such as methanol, butanol or 2-ethylhexanol) solution of the aldehyde compound.

[0185] R 4 -C(=O)-C(=O)-R 5Specific examples of the dicarbonyl compound represented by include glyoxal, methylglyoxal, diacetyl, 3,4-hexanedione, 2,3-pentanedione, 2,3-heptanedione, 5-methyl-2,3-hexanedione, 3-methyl-2,3-cyclopentanedione, 1,2-cyclohexanedione, 1-phenyl-1,2-propanedione, and dibenzoyl. The dicarbonyl compound is more preferably glyoxal, methylglyoxal or diacetyl, and more preferably glyoxal.

[0186] R 4 -C(=O)-C(=O)-R 5 The dicarbonyl compound represented can be used in the form of an aqueous solution of the dicarbonyl compound or an alcohol (such as methanol, butanol or 2-ethylhexanol) solution of the dicarbonyl compound.

[0187] R 6 Specific examples of the carboxylic acid represented by -COOH (formula (3)) include acetic acid, propionic acid, acrylic acid, propiolic acid, butyric acid, isobutyric acid, methacrylic acid, crotonic acid, butynoic acid, cyclopropanecarboxylic acid, valeric acid, isovaleric acid, pivalic acid, angelic acid, tiglic acid, cyclobutanecarboxylic acid, hexanoic acid, cyclopentanecarboxylic acid, heptanoic acid, sorbic acid, cyclohexanecarboxylic acid, benzoic acid, octanoic acid, 2-ethylhexylcarboxylic acid, toluic acid, 2-norbornanecarboxylic acid, nonanoic acid, cinnamic acid, decanoic acid, adamantanecarboxylic acid, geranic acid, undecanoic acid, lauric acid, and naphthylcarboxylic acid. The carboxylic acid is preferably acetic acid, propionic acid, acrylic acid, propiolic acid, butyric acid, isobutyric acid, methacrylic acid, crotonic acid, butynoic acid, valeric acid, isovaleric acid, pivalic acid, methoxyacetic acid, ethoxyacetic acid, propoxyacetic acid, (2-methoxyethoxy)acetic acid, (2-ethoxyethoxy)acetic acid, (2-propoxyethoxy)acetic acid, 3-(2-methoxyethoxy)propionic acid, 3-(2-ethoxyethoxy)propionic acid, 3-(2-propoxyethoxy)propionic acid, 3-(3-methoxypropoxy)propionic acid, 3-(3-ethoxypropoxy)propionic acid, 3-(3-propoxypropoxy)propionic acid, 3-[2-(2-methoxyethoxy)propionic acid]

[0063] The present invention is preferably acetic acid, methoxyacetic acid, acrylic acid, or methacrylic acid, but the present invention is not limited to these carboxylic acids.

[0188] R 1 -NH 2 and R 2 -NH 2The amount of the amine compound used is expressed as, per mole of dicarbonyl compound, R 1 -NH 2 and R 2 -NH 2 The total amount of R is preferably 0.1 mol to 10 mol, more preferably 0.5 mol to 3 mol. 1 With R 2 At the same time, the two amine compounds (R 1 -NH 2 and R 2 -NH 2 ) is not particularly limited, and in R 1 -NH 2 :R 2 -NH 2 =0:100 to 100:0. When R 1 -NH 2 :R 2 -NH 2 =0:100 or 100:0, R 1 =R 2 When it is not R 1 -NH 2 :R 2 -NH 2 =0:100 or 100:0, the onium salt represented by formula (1) obtained according to the reaction of formula (2) is a mixture of compounds represented by the following formula. The onium salt represented by formula (1) encompasses compounds represented by the following formula (1′) and formula (1″), and a mixture of these compounds can be used as the onium salt mixture described below. The mixture can be optionally purified to obtain a single desired compound, which can then be used as the onium salt represented by formula (1).

[0189]

[0190] R 3 The aldehyde compound represented by -CHO can be used in the form of an aqueous solution of the aldehyde compound or an alcohol solution of the aldehyde compound (such as methanol, butanol or 2-ethylhexanol). The amount of the aldehyde compound used is preferably 0.1 mol to 10 mol, more preferably 0.5 mol to 5 mol per mol of the dicarbonyl compound.

[0191] According to formula (2), R 6The amount of the carboxylic acid represented by -COOH (formula (3)) used is preferably in excess per mole of the imidazolium cation to be purified. The amount of the carboxylic acid is preferably 1.1 mol to 10 mol, more preferably 1.2 mol to 5 mol, and particularly preferably 1.5 mol to 3 mol per mole of the dicarbonyl compound. Therefore, the reaction of formula (2) produces a mixture containing the onium salt of formula (1) and the carboxylic acid of formula (3).

[0192] In the reaction of formula (2), a solvent may or may not be used. The solvent used may be any solvent that does not affect the reaction. Specific examples of the solvent include aromatic hydrocarbon solvents such as toluene, benzene, and xylene; hydrocarbon solvents such as methylcyclohexane, cyclohexane, hexane, heptane, and octane; halogenated hydrocarbon solvents such as dichloromethane and chloroform; ether solvents such as diethyl ether, tetrahydrofuran, and 1,4-dioxane; alcohol solvents such as methanol, ethanol, and 2-propanol; N,N-dimethylformamide, acetonitrile and water, preferably alcohol solvents and water.

[0193] The onium salt represented by the formula (1) prepared in advance can also be used as the reaction solvent of the reaction of formula (2). The solvent used can be a mixture of any two or more solvents. The amount of the solvent is preferably 50 parts by mass or less, more preferably 0.1 to 10 parts by mass, relative to each part by mass of the dicarbonyl compound.

[0194] The reaction of formula (2) can be optionally carried out in an inert gas atmosphere that does not affect the reaction, such as nitrogen, argon, or helium.

[0195] For the reaction of formula (2), the reaction pressure is usually atmospheric pressure. However, depending on the starting materials and / or solvents used, the reaction may be carried out by placing the reaction system under a high pressure of atmospheric pressure to 1 MPa.

[0196] For the reaction of formula (2), the optimum reaction temperature varies depending on the raw materials, solvents, etc. used, but is preferably -10°C or higher, more preferably 0°C to 100°C.

[0197] After the reaction of formula (2) is completed, the onium salt represented by formula (1) may or may not be purified according to known purification methods, including, but not limited to, concentration, liquid separation, recrystallization, dialysis, adsorption, and filtration.

[0198] The step (2) in the method for preparing the onium salt represented by the formula (1) of the present invention is the following step: adding an amine to the mixture containing the onium salt represented by the formula (1) and the carboxylic acid represented by the formula (3) obtained in the step (1) to generate an amine-carboxylate formed by the amine and the carboxylic acid represented by the formula (3).

[0199] The amine added in step (2) is preferably an amine represented by the following formula (4):

[0200] Formula (4):

[0201]

[0202] in,

[0203] R 7 , R 8 and R 9 may be the same or different and each represents a hydrogen atom or a C 1 -C 18 Hydrocarbon;

[0204] The C 1 -C 18 The hydrocarbon group may contain a double bond, and may contain a branched structure and / or a cyclic structure, and

[0205] R 7 , R 8 and R 9 The total number of carbon atoms contained is 8 or greater.

[0206] In formula (4), R 7 , R 8 and R 9 The number of carbon atoms of the hydrocarbon group represented is 1 to 18, more preferably 1 to 12, further preferably 1 to 8.

[0207] R 7 , R 8 and R 9 The total number of carbon atoms contained is 8 or more, preferably 12 or more and 24 or less.

[0208] R 7 , R 8 and R 9 Specific examples of the hydrocarbon radicals represented include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, octyl, 2-ethylhexyl, decyl, dodecyl, and octadecyl. Isopropyl, sec-butyl, isobutyl, tert-butyl, neopentyl, and 2-ethylhexyl each have a branched structure.

[0209] R 7 , R 8 and R 9 Specific examples of the hydrocarbon group containing a double bond represented by include vinyl, ethynyl, propenyl, isopropenyl, allyl, propargyl, butenyl, crotyl, butadienyl, and oleyl.

[0210] With R 7 , R 8 , or R 9Specific examples of the hydrocarbon group having a cyclic structure represented by include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyl, adamantyl, phenyl, benzyl, tolyl, styryl, and 2,4,6-trimethylphenyl. The cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyl, and adamantyl each have a branched structure. 7 , R 8 , and R 9 Preferred is a hydrogen atom, a methyl group, an oleyl group, a 2-ethylhexyl group, a cyclohexyl group, an octadecyl group, or an octyl group.

[0211] Specific examples of the amine represented by formula (4) include tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, oleylamine, di-2-ethylhexylamine, dicyclohexylamine, methyloctadecylamine, dimethyloctadecylamine, and trioctylamine.

[0212] The amount of amine added to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3) is 1 equivalent or more, preferably 1 to 1.5 equivalents, more preferably 1 to 1.2 equivalents, and particularly preferably 1 to 1.1 equivalents per equivalent of the carboxylic acid. An amine-carboxylate composed of the added amine and the carboxylic acid of formula (3) is generated, and a mixture of the onium salt of formula (1), the amine-carboxylate, and the remaining amine is obtained.

[0213] The amine can be added in the form of an amine solution prepared by diluting the amine with a solvent. Examples of solvents include chloroform, dichloromethane, 2-ethylhexanol, cyclohexanol, 1-octanol, and ethyl acetate, with chloroform, 2-ethylhexanol, cyclohexanol, and 1-octanol being preferred. The concentration of the amine solution is preferably 0.01 g / L to 10.0 g / L, more preferably 0.1 g / L to 5.00 g / L.

[0214] The reaction conditions for generating amine-carboxylate by adding amine to a mixture containing an onium salt represented by formula (1) and a carboxylic acid represented by formula (3) are as follows: the temperature is 0°C to 100°C, preferably 25°C to 80°C; and as for the reaction time, after adding the amine, the mixture is preferably stirred for 0.5 to 3 hours, more preferably 1 to 2 hours.

[0215] In a preferred embodiment of the present invention, the mixture in step 1 also contains water and a solvent. The solvent can be a solvent for diluting the amine to be added, or it can be a solvent added to the mixture in step 1 separately instead of being used to dilute the amine. The solvent contained in the mixture is preferably a solvent that separates from the water. Examples of solvents that separate from the water include hexane, heptane, toluene, chloroform, methylene chloride, 2-ethylhexanol, cyclohexanol, 1-octanol, and ethyl acetate. The solvent is preferably chloroform, 2-ethylhexanol, cyclohexanol, or 1-octanol.

[0216] When the mixture in step 1 contains water and the above-mentioned solvent, the added amine forms an amine-carboxylate and is mainly extracted into the solvent layer. On the other hand, the onium salt represented by formula (1) is present in the water layer. Therefore, separation of the solvent layer enables separation of the amine-carboxylate, thereby obtaining a water layer containing the onium salt represented by formula (1), wherein the amount of the carboxylic acid represented by formula (3) is reduced or the carboxylic acid is almost completely removed. It is difficult to remove the carboxylic acid of formula (3) present together with the onium salt of formula (1) by evaporation. However, the water in the water layer containing the onium salt of formula (1) can be easily removed by evaporation to obtain the onium salt of formula (1). The mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3) exhibits greatly reduced solubility of cellulose due to the presence of the carboxylic acid represented by formula (3) before undergoing the preparation method or purification method of the present invention. However, carrying out the preparation method or purification method of the present invention significantly improves the solubility of cellulose. For example, by removing 50% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, 95% or more, or 100% of the carboxylic acid represented by formula (3) from a mixture containing an onium salt represented by formula (1) and a carboxylic acid represented by formula (3), the solubility of cellulose is greatly improved.

[0217] Step (3) is a step of separating the onium salt represented by formula (1) from the amine-carboxylate salt produced in step (2). Examples of the separation method include liquid separation and crystallization.

[0218] The separation in step (3) provides a separated liquid containing the onium salt represented by formula (1). When the obtained separated liquid contains residual amine, the separated liquid may be heated and / or depressurized to distill off the residual amine.

[0219] When the amine is added in the form of an amine solution prepared by diluting the amine with a solvent, and the solvent is contained in the separated liquid containing the onium salt represented by formula (1) separated in step (3), the separated liquid may be heated and / or depressurized to distill off the solvent.

[0220] In the present invention, the onium salt represented by formula (1) may be one or a mixture of at least two. Specific examples of the mixture of at least two onium salts include a mixture of 1,3-dimethylimidazolium acetate and 1,3-diethylimidazolium acetate, a mixture of 1,3-dimethylimidazolium acetate and 1-ethyl-3-methylimidazolium acetate, a mixture of 1,3-diethylimidazolium acetate and 1-ethyl-3-methylimidazolium acetate, and a mixture of 1,3-dimethylimidazolium acetate, 1,3-diethylimidazolium acetate and 1-ethyl-3-methylimidazolium acetate.

[0221] In the present invention, the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3) may further contain water and / or a hydrophilic solvent. The hydrophilic solvent refers to a solvent that can be dissolved in water or miscible with water, and specific examples include C 1 -C 4 Lower alcohols, such as methanol, ethanol, propanol, and ethylene glycol.

[0222] The content of water and / or the hydrophilic solvent is 0.1 to 90% by mass, or 1 to 70% by mass, and preferably 5 to 50% by mass, based on 100% by mass of the total amount of the mixture containing the onium salt represented by formula (1), the carboxylic acid represented by formula (3), and water and / or the hydrophilic solvent.

[0223] One embodiment of the present invention relates to a method for purifying an onium salt represented by formula (1), comprising removing the carboxylic acid represented by formula (3) from a mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3),

[0224] The method comprises the following steps (1), (2) and (3):

[0225] Step (1), obtaining a mixture containing an onium salt represented by formula (1) and a carboxylic acid represented by formula (3), wherein the mixture is obtained according to the reaction route represented by formula (2),

[0226] step (2), adding an amine to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3) obtained in step (1) to generate an amine-carboxylate formed by the amine and the carboxylic acid represented by formula (3); and

[0227] Step (3) is to separate the onium salt represented by formula (1) from the amine-carboxylate produced in step (2) to obtain the onium salt represented by formula (1).

[0228] In the method for purifying an onium salt of the present invention, the onium salt represented by formula (1) is the same as the onium salt represented by formula (1) in the above-mentioned method for preparing an onium salt. In the method for purifying an onium salt of the present invention, in the onium salt represented by formula (1), the imidazolium cation represented by formula (1-1) is the same as the imidazolium cation represented by formula (1-1) in the above-mentioned method for preparing an onium salt. In the method for purifying an onium salt of the present invention, in the onium salt represented by formula (1), the carboxylate anion represented by formula (1-2) is the same as the carboxylate anion represented by formula (1-2) in the above-mentioned method for preparing an onium salt.

[0229] In the method for purifying an onium salt of the present invention, the carboxylic acid represented by the formula (3) is the same as the carboxylic acid represented by the formula (3) in the above-mentioned method for producing an onium salt.

[0230] In the method for purifying an onium salt of the present invention, the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3) obtained by the reaction of formula (2) in step (1) of the purification method is the same as the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3) obtained by the reaction of formula (2) in step (1) of the above-mentioned method for producing an onium salt.

[0231] In the purification method of the onium salt of the present invention, the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3) obtained by the reaction of formula (2) in step (1) of the purification method is a mixture in which the carboxylic acid represented by formula (3) used in the reaction of formula (2) and the onium salt represented by formula (1) remain together. The amount of the remaining carboxylic acid of formula (3) is usually 1.5 equivalents or less per equivalent of the onium salt of formula (1).

[0232] In the method for purifying an onium salt of the present invention, step (2) is the same as step (2) in the above-mentioned method for preparing an onium salt, and is the following step: an amine is added to a mixture containing an onium salt represented by formula (1) and a carboxylic acid represented by formula (3) to prepare an amine-carboxylate formed from the amine and the carboxylic acid represented by formula (3).

[0233] The amine added in step (2) of the method for purifying an onium salt of the present invention is preferably the amine represented by formula (4) in the above-mentioned method for producing an onium salt.

[0234] In step (2) of the method for purifying an onium salt of the present invention, the amount and preferred amount of the amine added to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3) are the same as the amount and preferred amount of the amine added in the above-mentioned method for preparing an onium salt. As in step (2) of the above-mentioned method for preparing an onium salt, step (2) of the method for purifying an onium salt of the present invention generates an amine-carboxylate formed from the added amine and the carboxylic acid of formula (3), providing a mixture of the onium salt represented by formula (1), the amine-carboxylate, and the remaining amine.

[0235] Like the amine added in step (2) of the above-mentioned method for preparing the onium salt, the amine added in step (2) of the method for purifying the onium salt of the present invention may be an amine solution prepared by diluting the amine with a solvent. The solvent may be the same as the solvent used in step (2) of the above-mentioned preparation method, and the concentration of the amine solution may be the same as the concentration of the amine solution used in step (2) of the preparation method.

[0236] In step (2) of the method for purifying an onium salt of the present invention, the reaction conditions for adding an amine to a mixture containing an onium salt represented by formula (1) and a carboxylic acid represented by formula (3) to generate an amine-carboxylate are the same as those in step (2) of the above-mentioned preparation method, such as temperature conditions and reaction time.

[0237] In the method for purifying an onium salt of the present invention, step (3) is the same as step (3) in the above method for preparing an onium salt, and is a step of separating the onium salt represented by formula (1) from the amine-carboxylate prepared in step (2). The separation method is the same as the separation method used in step (3) of the above method for preparing an onium salt.

[0238] The separation in step (3) of the method for purifying an onium salt of the present invention provides a separated liquid containing the onium salt represented by formula (1). When the obtained separated liquid contains residual amine and / or solvent of the amine solution, the obtained separated liquid can be heated and / or depressurized in the same manner as step (3) of the above-mentioned method for preparing an onium salt to distill off the remaining amine and / or solvent.

[0239] In the onium salt purification method of the present invention, the onium salt represented by formula (1) may be one or a mixture of at least two. The mixture of at least two is the same as the mixture of at least two onium salts represented by formula (1) in the above-mentioned onium salt preparation method.

[0240] In the method for purifying an onium salt of the present invention, as in the method for producing an onium salt described above, the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3) may further contain water and / or a hydrophilic solvent. The hydrophilic solvent may be the same as the hydrophilic solvent used in the method for producing the onium salt described above, and the content of water and / or the hydrophilic solvent is also the same as the content of water and / or the hydrophilic solvent in the method for producing the onium salt described above.

[0241] The onium salt prepared according to the method of the present invention can be used as, for example, a solvent for dissolving cellulose or a carbon dioxide absorbent.

[0242] Example

[0243] The present invention will be described in detail below with reference to Examples. However, the present invention is not limited to these Examples.

[0244] Example 1

[0245] Into a 1L four-necked reactor purged with nitrogen, 113 g (1.40 mol) of a 37 wt% formaldehyde aqueous solution (manufactured by Junsei Chemical Co., Ltd.), 126 g (2.10 mol) of acetic acid (manufactured by Junsei Chemical Co., Ltd.), 250 g (2.81 mol) of 3-methoxypropylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) and 202 g (1.40 mol) of a 40 wt% glyoxal aqueous solution (manufactured by Tokyo Chemical Industry Co., Ltd.) were added. The resulting mixture was heated to 40°C and stirred for 3 hours to synthesize 691 g of an aqueous solution of 1,3-bis(3-methoxypropyl)imidazolium acetate ([(MeOPr) 2 Im][AcO]). The synthesized substance is referred to as "reaction solution" below.1 H NMR analysis was performed to determine the integrated value of the peaks from acetate ion and acetic acid at 1.55 ppm to 1.65 ppm. The integrated value of the peak at 1.55 ppm to 1.65 ppm was 4.66 based on the peak at 1.94 ppm to 2.14 ppm (quintet, 4H).

[0246] To 10.0 g of the reaction solution were added 5.57 g of ion exchange water, 10.0 g of chloroform (manufactured by Junsei Chemical Co., Ltd.) and individual amines (0.02 mol) shown in Evaluation Examples 1 to 4 in Table 1, and the mixture was stirred and subjected to liquid separation. About 3 drops of the aqueous layer were added to about 1 g of DMSO-d6 to prepare 1 Sample for H NMR analysis The integrated value of the peak at 1.55 ppm to 1.65 ppm was determined based on the peak at 1.94 ppm to 2.14 ppm (quintet, 4H), and the removal rate (%) of acetic acid was calculated using the following formula.

[0247] Acetic acid removal rate (%) = (1-(integral value-3.00) / (4.66-3.00)) × 100

[0248] In Evaluation Example 2, since the peak derived from dicyclohexylamine overlaps with the peaks derived from acetate ions and acetic acid, the removal rate was calculated after removing the 2H component derived from the amine.

[0249] The results are shown in Table 1. Since the onium salts obtained by using the amines of Evaluation Examples 1 to 3 were obtained by removing acetic acid therefrom, all of them were able to increase the solubility of cellulose compared to the onium salts before removing acetic acid. However, the onium salt obtained by using the amine of Evaluation Example 4 was estimated to be almost unable to increase the solubility of cellulose due to its low acetic acid removal rate.

[0250] Table 1

[0251] amine Removal rate Evaluation Example 1 Bis(2-ethylhexyl)amine 84.9 Evaluation Example 2 Dicyclohexylamine 75.3 Evaluation Example 3 Dibutylamine 54.2 Evaluation Example 4 Triethylamine 5.4

[0252] Example 2

[0253] To 10.0 g of the reaction solution obtained in Example 1 were added 5.57 g of ion-exchanged water, 10.0 g of 2-ethylhexanol (manufactured by Junsei Chemical Co., Ltd.) and the individual amines (0.02 mol) of Evaluation Examples 5 and 6 shown in Table 2, and the mixture was stirred and subjected to liquid separation. About 3 drops of the aqueous layer were added to about 1 g of DMSO-d6 to prepare a 1The sample was analyzed by H NMR. The integral value of the peaks from acetate ions and acetic acid at 1.55 ppm to 1.65 ppm was determined based on the peaks (quintuple, 4H) at 1.94 ppm to 2.14 ppm, and the removal rate (%) of acetic acid was calculated using the following formula. As described in Example 1, the integral value of the peaks at 1.55 ppm to 1.65 ppm of the reaction solution was 4.66.

[0254] Acetic acid removal rate (%) = (1-(integral value-3.00) / (4.66-3.00)) × 100

[0255] In Evaluation Example 6, since the peak derived from dicyclohexylamine overlaps with the peaks derived from acetate ions and acetic acid, the removal rate was calculated after removing the 2H component derived from the amine.

[0256] The results are shown in Table 2. Since the onium salts obtained using the amines of Evaluation Examples 5 to 7 were obtained by removing acetic acid therefrom, all of the onium salts were able to increase the solubility of cellulose compared with the onium salts before removing acetic acid.

[0257] Table 2

[0258] amine Removal rate Evaluation Example 5 Bis(2-ethylhexyl)amine 84.9 Evaluation Example 6 Dicyclohexylamine 77.1 Evaluation Example 7 Dibutylamine 60.8

[0259] Example 3

[0260] Into a nitrogen-purged 30 mL three-necked reactor were added 1.69 g (0.21 mol) of a 37 wt% aqueous formaldehyde solution (manufactured by Junsei Chemical Co., Ltd.), 1.83 g (0.30 mol) of acetic acid (manufactured by Junsei Chemical Co., Ltd.), 1.63 g (0.21 mol) of a 40% methanol solution of methylamine (manufactured by Tokyo Chemical Industry Co., Ltd.), 1.32 g (0.20 mol) of a 70% aqueous ethylamine solution (manufactured by Tokyo Chemical Industry Co., Ltd.), and 2.99 g (0.21 mol) of a 40 wt% aqueous solution of glyoxal (manufactured by Tokyo Chemical Industry Co., Ltd.). The resulting mixture was heated to 40° C. and stirred for 3 hours to synthesize 8.97 g of an aqueous solution of a mixture of 1,3-dimethylimidazolium acetate, 1,3-diethylimidazolium acetate, and 1-ethyl-3-methylimidazolium acetate.

[0261] The reaction solution is subjected to 1 H NMR analysis was performed to determine the integrated value of the peaks from acetate ion and acetic acid at 1.55 ppm to 1.65 ppm. The integral of the peak at 1.55 ppm to 1.67 ppm was 4.70 based on the peak at 7.55 ppm to 7.75 ppm (m, 2H).

[0262] To the reaction solution were added 5.22 g of ion exchanged water, 4.77 g of 2-ethylhexanol, and 2.72 g (0.21 mol) of di-2-ethylhexylamine, and the mixture was stirred and subjected to liquid separation. About 3 drops of the aqueous layer were added to about 1 g of DMSO-d6 to prepare 1 Sample for H NMR analysis The integrated value of the peak at 1.55 ppm to 1.67 ppm was determined based on the peak at 7.55 ppm to 7.75 ppm (m, 2H), and the removal rate (%) of acetic acid was calculated using the following formula.

[0263] Acetic acid removal rate (%) = (1-(integral value-3.00) / (4.70-3.00)) × 100

[0264] The results are shown in Table 3. Since the onium salt obtained using the amine of Evaluation Example 8 is one from which acetic acid has been removed, the onium salt can increase the solubility of cellulose compared with the onium salt before the removal of acetic acid.

[0265] Table 3

[0266] amine Removal rate Evaluation Example 8 Di-2-ethylhexylamine 96.5

[0267] Example 4

[0268] Into a 300 L four-necked reactor purged with nitrogen, 28.40 g (0.35 mol) of a 37 wt% aqueous formaldehyde solution (manufactured by Junsei Chemical Co., Ltd.), 31.59 g (0.53 mol) of acetic acid (manufactured by Junsei Chemical Co., Ltd.), 62.31 g (0.70 mol) of 3-methoxypropylamine (manufactured by Tokyo Chemical Industry Co., Ltd.), and 50.45 g (0.35 mol) of a 40 wt% aqueous glyoxal solution (manufactured by Tokyo Chemical Industry Co., Ltd.) were added. The resulting mixture was heated to 40° C. and stirred for 3 hours to synthesize 172 g of an aqueous 1,3-bis(3-methoxypropyl)imidazolium acetate solution ([(MeOPr] 2 Im][AcO]). The synthesized substance is referred to as "reaction solution" below. The reaction solution is concentrated and subjected to 1 H NMR analysis and cellulose dissolution test. 1 The results of H NMR analysis showed that the integrated value of the peaks derived from acetate ion and acetic acid based on the peaks at 1.94 ppm to 2.14 ppm (quintet, 4H) was 4.49.

[0269] Removal of acetic acid

[0270] Ion exchange water (8.36 g), chloroform (15.0 g) (manufactured by Junsei Chemical Co., Ltd.), and the individual amines shown in Table 4 (0.03 mol) were added to the reaction solution (15.0 g), and the mixture was stirred and allowed to stand (80° C., 1 hour each). After liquid separation, the lower layer was concentrated and subjected to 1 H NMR Analysis and Cellulose Dissolution Test. These are hereinafter referred to as "Evaluation Examples 9 to 11" and "Comparative Example 2." In Comparative Example 1, a cellulose dissolution test was performed in the same manner as above, except that no amine was used.

[0271] In the NMR analysis, the integral value of the peak from acetic acid was confirmed. The integral value of the peak at 1.55ppm to 1.65ppm was measured based on the peak at 1.94ppm to 2.14ppm (quintuplet, 4H), and the removal rate (%) of acetic acid was calculated from the integral value. The formula is as follows:

[0272] Acetic acid removal rate (%) = (1-(integral value-3.00) / (4.49-3.00)) × 100

[0273] In Evaluation Example 10, since the peak derived from dicyclohexylamine overlapped with the peak derived from acetic acid, the removal rate was calculated after removing the 2H component derived from the amine. Table 5 shows the results.

[0274] Dissolution test

[0275] A dissolution test was conducted to confirm whether microcrystalline cellulose (10 wt % relative to the concentrate) (Avicel (registered trademark) PH-101, manufactured by Sigma-Aldrich Co.) could be dissolved at 25°C.

[0276] The concentrated solution of the reaction solution (Comparative Example 1) and the concentrated solutions (1.0 g) of Evaluation Examples 9 to 11 and Comparative Example 2 were each placed in a test tube, and microcrystalline cellulose (10 wt % relative to the concentrated solution) was added and stirred at 25°C. After 24 hours, it was visually checked whether the microcrystalline cellulose was dissolved. The sample in which the crystalline cellulose was completely dissolved was marked with "√", and the sample in which the crystalline cellulose was not completely dissolved was marked with "×". Table 5 shows the dissolution results.

[0277] Example 5

[0278] Removal of acetic acid

[0279] Ion exchange water (8.36 g), 2-ethylhexanol (15.0 g) (manufactured by Junsei Chemical Co., Ltd.), and the individual amines shown in Table 1 (0.03 mol) were added to the reaction solution (15.0 g) obtained in Example 4, and the mixture was stirred and allowed to stand (80° C., 1 hour each). After liquid separation, the lower layer was concentrated and subjected to 1H NMR analysis and dissolution test. These are hereinafter referred to as "Evaluation Examples 12 to 14".

[0280] In the NMR analysis, the integral value of the peak from acetic acid was confirmed. The integral value of the peak at 1.55ppm to 1.65ppm was measured based on 1.94ppm to 2.14ppm (quintuplet, 4H), and the removal rate (%) of acetic acid was calculated from the integral value. The formula is as follows:

[0281] Acetic acid removal rate (%) = (1-(integral value-3.00) / (4.49-3.00)) × 100

[0282] In Evaluation Example 13, since the peak derived from dicyclohexylamine overlapped with the peak derived from acetic acid, the removal rate was calculated after removing the 2H component derived from the amine. Table 6 shows the results.

[0283] Dissolution test

[0284] A dissolution test was conducted to confirm whether microcrystalline cellulose (10 wt % relative to the concentrate) (Avicel (registered trademark) PH-101, manufactured by Sigma-Aldrich Co.) could be dissolved at 25°C.

[0285] The concentrated solutions (1.0 g) of Evaluation Examples 12 to 14 were each placed in a test tube, and microcrystalline cellulose (10 wt % relative to the concentrated solution) was added at 25°C and stirred. After 24 hours, it was visually checked whether the microcrystalline cellulose was dissolved. The samples in which the crystalline cellulose was completely dissolved were marked with "√", and the samples in which the crystalline cellulose was not completely dissolved were marked with "×". Table 6 shows the dissolution results.

[0286] Table 4

[0287] amine source Bis(2-ethylhexyl)amine Koei Chemical Co., Ltd. Dicyclohexylamine Tokyo Chemical Industry Co., Ltd. Dibutylamine Tokyo Chemical Industry Co., Ltd. Triethylamine Tokyo Chemical Industry Co., Ltd.

[0288] Table 5

[0289]

[0290] Table 6

[0291]

[0292] Industrial Applicability

[0293] The present invention provides a method for preparing an onium salt containing no carboxylic acid or an onium salt having a carboxylic acid content reduced to such an extent that cellulose has sufficient solubility in the onium salt. The present invention also provides a method for purifying the onium salt by removing the carboxylic acid contained in the onium salt or reducing the carboxylic acid content to such an extent that cellulose has sufficient solubility in the onium salt.

Claims

1. A method for preparing an onium salt represented by the following formula (1): Formula (1) in, R 1 , R 2 , R 3 , R 4 and R 5 may be the same or different and each represents a hydrogen atom or a hydrocarbon group optionally containing at least one heteroatom, R 1 , R 2 , R 3 , R 4 and R 5 may contain branched chains and / or cyclic structures and / or double bonds, R 1 , R 2 , R 3 , R 4 and R 5 Some or all of R 1 , R 2 , R 3 , R 4 and R 5 The bound nitrogen atoms and / or carbon atoms together may form a ring structure, and R 6 represents a hydrocarbon group which optionally contains at least one heteroatom and may contain a double bond and / or a cyclic structure and / or a branched structure, The method comprises the following steps (1), (2) and (3): Step (1), obtaining a mixture containing an onium salt represented by formula (1) and a carboxylic acid represented by the following formula (3), wherein the mixture is obtained according to the reaction route represented by the following formula (2): Formula (2) Formula (3) Where R 6 represents a hydrocarbon group which optionally contains at least one heteroatom and may contain a double bond and / or a cyclic structure and / or a branched structure, Step (2), adding an amine to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3) obtained in step (1) to generate an amine-carboxylate formed by the amine and the carboxylic acid represented by formula (3); as well as Step (3) is to separate the onium salt represented by formula (1) from the amine-carboxylate produced in step (2) to obtain the onium salt represented by formula (1).

2. The method for preparing an onium salt according to claim 1, wherein The amine added in step (2) is an amine represented by the following formula (4): Formula (4) in, R 7 , R 8 and R 9 may be the same or different and each represents a hydrogen atom or a C1-C 18 Hydrocarbon, C1-C 18 The hydrocarbon group may contain a double bond, and may contain a branched structure and / or a cyclic structure, and R 7 , R 8 and R 9 The total number of carbon atoms contained in each is 8 or greater.

3. The method for preparing an onium salt according to claim 1, wherein: The onium salt represented by formula (1) is of at least two types.

4. The method for preparing an onium salt according to claim 1, wherein: The mixture containing the onium salt represented by the formula (1) and the carboxylic acid represented by the formula (3) further contains water and / or a hydrophilic solvent.

5. The method for preparing an onium salt according to claim 1, wherein: The amine added in step (2) is an amine solution prepared by diluting the amine with a solvent.

6. A method for purifying an onium salt represented by the following formula (1), comprising removing the carboxylic acid represented by the following formula (3) from a mixture containing the onium salt represented by the following formula (1) and the carboxylic acid represented by the following formula (3), Formula (1) in, R 1 , R 2 , R 3 , R 4 and R 5 may be the same or different and each represents a hydrogen atom or a hydrocarbon group optionally containing at least one heteroatom, R 1 , R 2 , R 3 , R 4 and R 5 may contain branched chains and / or cyclic structures and / or double bonds, R 1 , R 2 , R 3 , R 4 and R 5 Some or all of R 1 , R 2 , R 3 , R 4 and R 5 The bound nitrogen atoms and / or carbon atoms together may form a ring structure, and R 6 represents a hydrocarbon group which optionally contains at least one heteroatom and may contain a double bond and / or a cyclic structure and / or a branched structure, The method comprises the following steps (1), (2) and (3): Step (1), obtaining a mixture containing an onium salt represented by formula (1) and a carboxylic acid represented by formula (3), wherein the mixture is obtained according to the reaction route represented by the following formula (2): Formula (2) Formula (3) Where R 6 represents a hydrocarbon group which optionally contains at least one heteroatom and may contain a double bond and / or a cyclic structure and / or a branched structure, Step (2), adding an amine to the mixture containing the onium salt represented by formula (1) and the carboxylic acid represented by formula (3) obtained in step (1) to generate an amine-carboxylate formed by the amine and the carboxylic acid represented by formula (3); as well as Step (3) is to separate the onium salt represented by formula (1) from the amine-carboxylate produced in step (2) to obtain the onium salt represented by formula (1).

7. The method for purifying an onium salt according to claim 6, wherein: The amine added in step (2) is an amine represented by the following formula (4): Formula (4) in, R 7 , R 8 and R 9 may be the same or different and each represents a hydrogen atom or a C1-C 18 Hydrocarbon, C1-C 18 The hydrocarbon group may contain a double bond, and may contain a branched structure and / or a cyclic structure, and R 7 , R 8 and R 9 The total number of carbon atoms contained in each is 8 or greater.

8. The method for purifying an onium salt according to claim 6, wherein: The onium salt represented by formula (1) is of at least two types.

9. The method for purifying an onium salt according to claim 6, wherein: The mixture containing the onium salt represented by the formula (1) and the carboxylic acid represented by the formula (3) further contains water and / or a hydrophilic solvent.

10. The method for purifying an onium salt according to claim 6, wherein: The amine added in step (2) is an amine solution prepared by diluting the amine with a solvent.

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