Carbene compound and method for producing same

Abstract

To provide a carbene compound that can be isolated and has stability and a method for producing the same.SOLUTION: A method for producing a carbene compound represented by the formula (2) includes heating a carbonate salt represented by the formula (1) in a solvent (where R1, R2, R3, R4, R5, R6, R7, R8 and R9 are defined in the specifications).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a carbene compound and a method for producing the same. [Background technology]

[0002] Carbene compounds, such as N-heterocyclic carbene compounds, are used as ligands in a variety of organometallic catalysts. As a general method for producing a carbene compound, for example, a method of reacting a bisamino chloride compound with a strongly basic compound such as sodium hydride or potassium tert-butoxide is known (Non-Patent Documents 1 and 2). In general, carbene compounds are unstable in the atmosphere. When they are used as ligands for organometallic catalysts, they are generated in solution and coordinated directly to metal atoms, and few attempts have been made to isolate the carbene compounds.

[0003] Non-Patent Document 3 describes 1,3-disubstituted imidazolium hydrogen carbonate (HCO3 - ) can be used as a raw material to produce metal complexes with 1,3-disubstituted imidazolium hydrogen carbonate (HCO3 - ) has been shown to be in equilibrium with carbenes. However, 1,3-disubstituted imidazolium bicarbonates (HCO3 - ) directly from the 1,3-disubstituted imidazolium hydrogen carbonate (HCO3 - Although it is possible to obtain compounds that can be synthesized from carbenes (for example, 1,3-disubstituted imidazole-2-carboxylates produced by reacting carbene with the generated CO2, and the metal complexes mentioned above), it has been thought to be difficult to isolate only the carbene. Furthermore, when the inventors of the present application heated an aqueous solution of 1,3-dimethylimidazolium hydrogencarbonate in a chlorobenzene solvent, 1,3-dimethylimidazolium-2-carboxylate was obtained in which water was eliminated from 1,3-dimethylimidazolium hydrogencarbonate, rather than from a carbene compound (see Comparative Example 1 described later). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Journal of the American Chemical Society 1991, 113, 1, 361-363. [Non-Patent Document 2] Journal of the American Chemical Society, 1994, 116, 6641-6649. [Non-Patent Document 3] Journal of the American Chemical Society 2012, 134, 6776-6784. Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional methods for producing carbene compounds require the use of strongly basic compounds that are highly toxic, such as corrosive to the skin, and their use is not preferred from the standpoint of safety. Therefore, an object of the present invention is to provide a method for producing carbene compounds without using strongly basic compounds. When a carbene compound is generated in a solution using a strongly basic compound and used in a subsequent reaction, the reaction becomes complicated due to the presence of various impurities. Another object of the present invention is to provide a novel production method capable of isolating a carbene compound from a carbonate salt, and a novel carbene compound. [Means for solving the problem]

[0006] The present invention includes the following carbene compounds and methods for producing the same. [1] A method for producing a carbene compound represented by the following formula (2), comprising heating a carbonate salt represented by the following formula (1) in a solvent. Formula (1): [ka] (In the formula, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 R may be the same or different and represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. 1 and R 2 , R 2 and R 3 , R 6 and R 7 , or R 7 and R 8 may form a ring structure together with the carbon atom to which they are attached. 4 and R 5 may form a ring structure together with the nitrogen atom to which they are attached. CR 1 R 2 R 3 or a group represented by CR 6 R 7 R 8 The group represented by R may be an adamantyl group. 9 represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. Formula (2): [ka] (In the formula, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each as defined above.) [2] The method for producing a carbene compound according to [1], comprising heating the solvent to a temperature higher than the boiling point of water, the boiling point of the solvent being higher than the boiling point of water. [3] The method for producing a carbene compound according to [1] or [2], wherein the reaction temperature is 40 to 200° C. [4] The method for producing a carbene compound according to any one of [1] to [3], wherein the carbonate salt represented by the formula (1) is a carbonate salt represented by the following formula (1-1): Formula (1-1): [ka] (In the formula, R 1 , R 2 , R 3 , R 6 , R 7 , R 8 and R 9 are each as defined above. L represents a bridged structure having 2 to 40 carbon atoms linking nitrogen atoms together, and may have a double bond, may have a monocyclic structure or a condensed ring structure, and may have a substituent. [5] The method for producing a carbene compound according to [4], wherein the carbonate salt represented by formula (1) is a carbonate salt represented by either formula (1-2) or formula (1-3): Formula (1-2): [ka] (In the formula, R 1 , R 2 , R 3 , R 6 , R 7 , R 8 and R 9 Each is as defined above. 10 and R 11 R are the same or different and each represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom. 10 and R 11may form a ring structure together with the carbon atom to which they are attached. Formula (1-3): [ka] (In the formula, R 1 , R 2 , R 3 , R 6 , R 7 , R 8 and R 9 Each is as defined above. 12 and R 13 R are the same or different and each represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom. 12 and R 13 may form a ring structure together with the carbon atom to which they are attached. [6] R 1 , R 2 , R 3 , R 6 , R 7 and R 8 and are the same or different and are alkyl groups having 1 to 8 carbon atoms. [1] - [5] The method for producing a carbene compound according to any one of [1] to [5]. [7] The method for producing a carbene compound according to any one of [1] to [6], wherein the solvent is an aromatic hydrocarbon solvent, an aliphatic or alicyclic hydrocarbon solvent, or a halogenated aromatic hydrocarbon solvent. [8] A carbene compound represented by the following formula (2): Formula (2): [ka] (In the formula, R 1 , R 2 , R 4 , R 5 , R 6 and R 7 R may be the same or different and represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. 3 and R 8R may be the same or different and represents a hydrocarbon group having 2 to 20 carbon atoms which may contain a heteroatom. 1 and R 2 , R 2 and R 3 , R 6 and R 7 , or R 7 and R 8 may form a ring structure together with the carbon atom to which they are attached. 4 and R 5 may form a ring structure together with the nitrogen atom to which they are attached. [9] The carbene compound according to [8], represented by the following formula (2-1): Formula (2-1): [ka] (In the formula, R 1 , R 2 , R 3 , R 6 , R 7 and R 8 are each as defined above. L represents a bridged structure having 2 to 40 carbon atoms linking nitrogen atoms together, and may have a double bond, may have a monocyclic structure or a condensed ring structure, and may have a substituent.

[10] The carbene compound according to [8] or [9], represented by the following formula (2-2) or formula (2-3): Formula (2-2): [ka] (In the formula, R 1 , R 2 , R 3 , R 6 , R 7 and R 8 Each is as defined above. 10 and R 11 R are the same or different and each represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom. 10 and R 11may form a ring structure together with the carbon atom to which they are attached. Formula (2-3): [ka] (In the formula, R 1 , R 2 , R 3 , R 6 , R 7 and R 8 Each is as defined above. 12 and R 13 R are the same or different and each represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom. 12 and R 13 may form a ring structure together with the carbon atom to which they are attached.

[11] A carbene compound according to [8], represented by the following formula: [ka] Effect of the Invention

[0007] According to the present invention, a carbene compound can be produced from a carbonate salt. The carbonate salt generates water or alcohol and CO2 when heated, and a high-purity carbene compound can be obtained by removing these. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described in detail.

[0009] In the present invention, the carbene compound represented by formula (2) (hereinafter referred to as carbene compound (2)) is produced by heating the carbonate salt represented by formula (1) (hereinafter referred to as carbonate salt (1)).

[0010] In order to obtain the carbene compound (2), the carbonate salt (1) is preferably heated in a solvent. Specific examples of the solvent include aromatic hydrocarbon solvents such as toluene, benzene, xylene, etc., aliphatic or alicyclic hydrocarbon solvents such as methylcyclohexane, cyclohexane, hexane, heptane, octane, etc., halogenated aromatic hydrocarbon solvents such as chlorobenzene, and ether solvents such as diethyl ether, tetrahydrofuran, 1,4-dioxane, etc., and aromatic hydrocarbon solvents, aliphatic or alicyclic hydrocarbon solvents, and halogenated aromatic hydrocarbon solvents are preferred, with toluene being particularly preferred. In the production method of the present invention, in the carbonate salt (1), R 9 is a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, the alcohol (R 9 In the carbonate salt (1), R 9 When R is a hydrogen atom, water is produced as a by-product. Therefore, in order to remove water or alcohol, R 9 When R is a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, the by-product alcohol (R 9 It is preferable to use a solvent having a higher boiling point than that of R 9 When is a hydrogen atom, it is preferable to use a solvent having a boiling point higher than that of water. Two or more kinds of solvents can be mixed and used as necessary.

[0011] The amount of the solvent used is usually 150 parts by mass or less, and preferably 0.1 to 120 parts by mass, per part by mass of the carbonate salt (1).

[0012] The reaction temperature is preferably 40 to 200° C., more preferably 60 to 150° C., and further preferably 80 to 130° C. The reaction is preferably carried out near the boiling point of the solvent, for example, under reflux. In the production method of the present invention, water or alcohol (R 9 In order to generate the carbene compound (2-2) R 10 or R 11When is a hydrogen atom, if the reaction temperature is too high, the carbene carbon may migrate to the thermodynamically stable C4 or C5 position instead of between the two nitrogen atoms (C2 position), so a reaction temperature of 150 °C or less is preferred.

[0013] The reaction time is usually 1 to 120 hours, preferably 1 to 48 hours.

[0014] In addition, the reaction pressure is usually preferably atmospheric pressure or less. In the production method of the present invention, water or alcohol (R 9 Since the reaction proceeds by removing the --OH) and CO2, the reaction can be carried out under reduced pressure. For example, a reaction pressure of 30 to 101 kPa is preferred.

[0015] In the production method of the present invention, the reaction may be carried out in an inert gas atmosphere that does not affect the reaction, such as nitrogen, argon, or helium, if necessary.

[0016] The resulting carbene compound (2) can be purified by a conventional method such as concentration or recrystallization.

[0017] Carbonate salt (1) is a hydrogen carbonate salt (HO-CO-O - , R 9 =H) and carbonate monoester salt (R 9 O-C-O - , R 9 = a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom).

[0018] The carbonate salt (1) will be explained.

[0019] In formula (1), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8represents a hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a heteroatom, is preferably a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a heteroatom, and is particularly preferably a hydrocarbon group having 1 to 8 carbon atoms which may be substituted with a heteroatom. In this case, a more preferred embodiment is R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 represents an alkyl group having 1 to 20 carbon atoms which may be substituted with a heteroatom, preferably an alkyl group having 1 to 12 carbon atoms which may be substituted with a heteroatom, and particularly preferably an alkyl group having 1 to 8 carbon atoms which may be substituted with a heteroatom. In another embodiment, preferably, R 3 and R 8 represents a hydrocarbon group having 2 to 20 carbon atoms which may be substituted with a heteroatom, preferably a hydrocarbon group having 2 to 12 carbon atoms which may be substituted with a heteroatom, and particularly preferably a hydrocarbon group having 2 to 8 carbon atoms which may be substituted with a heteroatom. 3 and R 8 represents an alkyl group having 2 to 20 carbon atoms which may be substituted with a heteroatom, preferably an alkyl group having 2 to 12 carbon atoms which may be substituted with a heteroatom, and particularly preferably an alkyl group having 2 to 8 carbon atoms which may be substituted with a heteroatom. Alternatively, R 1 , R 2 , R 6 and R 7 is a phenyl group, R 3 and R 8 is preferably other than a phenyl group.

[0020] Examples of the hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a heteroatom include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, an octyl group, a 1,1,3,3-tetramethylbutyl group, a 2-ethylhexyl group, a decyl group, a dodecyl group, a tetradecyl group, a hexadecyl group, an octadecyl group, an allyl group, a benzyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, a phenyl group, a 2,6-diisopropylphenyl group, a 2,4,6-trimethylphenyl group, a 2-methoxyethyl group, a 2-ethoxyethyl group, and a 2-(dimethylamino)ethyl group. Preferred are a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a neopentyl group, an octyl group, a 1,1,3,3-tetramethylbutyl group, a 2-ethylhexyl group, a dodecyl group, a benzyl group, a cyclopentyl group, a cyclohexyl group, a phenyl group, and a 2,4,6-trimethylphenyl group, and particularly preferred are a methyl group, an ethyl group, a butyl group, a neopentyl group, an octyl group, a 1,1,3,3-tetramethylbutyl group, a 2-ethylhexyl group, and a phenyl group. R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 In the above, examples of the heteroatom include a nitrogen atom, an oxygen atom, and a sulfur atom. When a hydrocarbon group or an alkyl group is substituted with a heteroatom such as an oxygen atom, a nitrogen atom, or a sulfur atom, the hydrocarbon group or the alkyl group has a group such as -O-, -N<, -S-, or -SO2-, and the hydrocarbon chain or the alkyl chain is interrupted by these groups. When a hydrocarbon group or an alkyl group is substituted with a heteroatom such as an oxygen atom, a nitrogen atom, or a sulfur atom, it is preferable that the hydrocarbon group or the alkyl group is substituted with an oxygen atom, and the hydrocarbon chain or the alkyl chain is interrupted by an -O- group. R 1 and R 2 , R 2 and R 3 , R 6 and R 7, or R 7 and R 8 may form a ring structure together with the carbon atom to which they are attached. 4 and R 5 may form a ring structure together with the nitrogen atom to which they are attached.

[0021] R 9 represents a hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a hydrogen atom or a heteroatom, is preferably a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a hydrogen atom or a heteroatom, and is particularly preferably a hydrocarbon group having 1 to 8 carbon atoms which may be substituted with a hydrogen atom or a heteroatom. Examples of the hydrocarbon group having 1 to 20 carbon atoms, which may be substituted with a heteroatom, include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, an octyl group, a 1,1,3,3-tetramethylbutyl group, a 2-ethylhexyl group, a decyl group, a dodecyl group, a tetradecyl group, a hexadecyl group, an octadecyl group, an allyl group, a benzyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, a phenyl group, a 2,6-diisopropylphenyl group, a 2,4,6-trimethylphenyl group, a 2-methoxyethyl group, a 2-ethoxyethyl group, and a 2-(dimethylamino)ethyl group. Methyl, ethyl, propyl, and butyl groups are preferred, and methyl is particularly preferred. R 9 In the above, examples of the heteroatom include a nitrogen atom, an oxygen atom, and a sulfur atom. When the hydrocarbon group is substituted with a heteroatom such as an oxygen atom, a nitrogen atom, or a sulfur atom, the hydrocarbon group has a group such as -O-, -N<, -S-, or -SO2-, and the hydrocarbon chain is interrupted by these groups. When the hydrocarbon group is substituted with a heteroatom such as an oxygen atom, a nitrogen atom, or a sulfur atom, it is preferable that the hydrocarbon group is substituted with an oxygen atom and the hydrocarbon chain is interrupted by an -O- group.

[0022] The carbonate salt (1) is preferably a carbonate salt represented by formula (1-1) (hereinafter referred to as carbonate salt (1-1)), and more preferably a carbonate salt represented by formula (1-2) (hereinafter referred to as carbonate salt (1-2)) or a carbonate salt represented by formula (1-3) (hereinafter referred to as carbonate salt (1-3)). Formula (1-1):

[0023] [ka] (In the formula, R 1 , R 2 , R 3 , R 6 , R 7 , R 8 and R 9 are each as defined above. L represents a bridged structure having 2 to 40 carbon atoms linking nitrogen atoms together, and may have a double bond, may have a monocyclic structure or a condensed ring structure, and may have a substituent. Formula (1-2):

[0024] [ka] (In the formula, R 1 , R 2 , R 3 , R 6 , R 7 , R 8 and R 9 Each is as defined above. 10 and R 11 R are the same or different and each represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom. 10 and R 11 may form a ring structure together with the carbon atom to which they are attached. Formula (1-3):

[0025] [ka] (In the formula, R 1 , R 2 , R3 , R 6 , R 7 , R 8 and R 9 Each is as defined above. 12 and R 13 R are the same or different and each represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom. 12 and R 13 may form a ring structure together with the carbon atom to which they are attached.

[0026] In formula (1), R 4 and R 5 However, the ring structure formed together with the nitrogen atom to which they are bonded includes carbonate salt (1-1), and more preferred embodiments include carbonate salt (1-2) and carbonate salt (1-3).

[0027] In formula (1-1), L represents a bridged structure having 2 to 40 carbon atoms linking nitrogen atoms, and may have a double bond, may have a monocyclic structure or a condensed ring structure, and may have a substituent. The number of carbon atoms in L is preferably 2 to 10, more preferably 2 to 6, and particularly preferably 2. Examples of the monocyclic structure include imidazole, imidazoline, and pyrimidine, and examples of the condensed ring structure include benzimidazole, benzimidazoline, and benzopyrimidine. When L is a bridged structure having 2 to 40 carbon atoms and has a substituent, examples of the substituent include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, a dialkylamino group such as a dimethylamino group, an alkoxy group such as a methoxy group and an ethoxy group, an aryloxy group such as a benzyloxy group, a halogenated alkyl group such as a trifluoromethyl group, a nitro group, a cyano group, and a sulfonyl group. In addition, the bridged structure of L may be substituted with at least one heteroatom such as an oxygen atom, a nitrogen atom, or a sulfur atom. When the bridged structure of L is substituted with at least one heteroatom such as an oxygen atom, a nitrogen atom, or a sulfur atom, the hydrocarbon group has at least one group such as -O-, -N<, -N=, or -S-, and the hydrocarbon chain is interrupted by these groups.

[0028] In formula (1-2), R 10 , R 11 represents a hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a hydrogen atom or a heteroatom, is preferably a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a hydrogen atom or a heteroatom, and is particularly preferably a hydrocarbon group having 1 to 8 carbon atoms which may be substituted with a hydrogen atom or a heteroatom. Examples of the hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a heteroatom include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, an octyl group, a 1,1,3,3-tetramethylbutyl group, a 2-ethylhexyl group, a decyl group, a dodecyl group, a tetradecyl group, a hexadecyl group, an octadecyl group, an allyl group, a benzyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, a phenyl group, a 2,6-diisopropylphenyl group, a 2,4,6-trimethylphenyl group, a 2-methoxyethyl group, a 2-ethoxyethyl group, and a 2-(dimethylamino)ethyl group. Preferred are a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a neopentyl group, an octyl group, a 1,1,3,3-tetramethylbutyl group, a 2-ethylhexyl group, a dodecyl group, a benzyl group, a cyclopentyl group, a cyclohexyl group, a phenyl group, and a 2,4,6-trimethylphenyl group, and particularly preferred are a methyl group, an ethyl group, a butyl group, a neopentyl group, an octyl group, a 1,1,3,3-tetramethylbutyl group, a 2-ethylhexyl group, and a phenyl group.

[0029] R 10 , R 11 In the above, examples of the heteroatom include a nitrogen atom, an oxygen atom, and a sulfur atom. When the hydrocarbon group is substituted with a heteroatom such as an oxygen atom, a nitrogen atom, or a sulfur atom, the hydrocarbon group has a group such as -O-, -N<, -S-, or -SO2-, and the hydrocarbon chain is interrupted by these groups. When the hydrocarbon group is substituted with a heteroatom such as an oxygen atom, a nitrogen atom, or a sulfur atom, it is preferable that the hydrocarbon group is substituted with an oxygen atom and the hydrocarbon chain is interrupted by an -O- group.

[0030] In formula (1-3), R 12 , R 13 represents a hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a hydrogen atom or a heteroatom, is preferably a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a hydrogen atom or a heteroatom, and is particularly preferably a hydrocarbon group having 1 to 8 carbon atoms which may be substituted with a hydrogen atom or a heteroatom. Examples of the hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a heteroatom include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, an octyl group, a 1,1,3,3-tetramethylbutyl group, a 2-ethylhexyl group, a decyl group, a dodecyl group, a tetradecyl group, a hexadecyl group, an octadecyl group, an allyl group, a benzyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, a phenyl group, a 2,6-diisopropylphenyl group, a 2,4,6-trimethylphenyl group, a 2-methoxyethyl group, a 2-ethoxyethyl group, and a 2-(dimethylamino)ethyl group. Preferred are a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a neopentyl group, an octyl group, a 1,1,3,3-tetramethylbutyl group, a 2-ethylhexyl group, a dodecyl group, a benzyl group, a cyclopentyl group, a cyclohexyl group, a phenyl group, and a 2,4,6-trimethylphenyl group, and particularly preferred are a methyl group, an ethyl group, a butyl group, a neopentyl group, an octyl group, a 1,1,3,3-tetramethylbutyl group, a 2-ethylhexyl group, and a phenyl group.

[0031] R 12 , R 13In the above, examples of the heteroatom include a nitrogen atom, an oxygen atom, and a sulfur atom. When the hydrocarbon group is substituted with a heteroatom such as an oxygen atom, a nitrogen atom, or a sulfur atom, the hydrocarbon group has a group such as -O-, -N<, -S-, or -SO2-, and the hydrocarbon chain is interrupted by these groups. When the hydrocarbon group is substituted with a heteroatom such as an oxygen atom, a nitrogen atom, or a sulfur atom, it is preferable that the hydrocarbon group is substituted with an oxygen atom and the hydrocarbon chain is interrupted by an -O- group.

[0032] In formula (1-2), R 10 and R 11 may form a ring structure together with the carbon atom to which they are attached. 10 and R 11 However, when they form a ring structure together with the carbon atom to which they are attached, they can take the form of, for example, a benzimidazolium ring structure as shown in the following formula (1-2x). Formula (1-2x):

[0033] [ka] (In the formula, R 1 , R 2 , R 3 , R 6 , R 7 , R 8 and R 9 is as defined above. w , R x , R y and R z Each represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms.

[0034] In formula (1-2x), R w , R x , R y or R zExamples of the hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a nonyl group, an undecyl group, a tridecyl group, a pentadecyl group, a heptadecyl group, a vinyl group, an allyl group, a benzyl group, a cyclohexyl group, an adamantyl group, a phenyl group, a 2-methoxymethyl group, a 2-ethoxymethyl group, a 2-(dimethylamino)methyl group, and the like. Of these, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a heptyl group, a cyclohexyl group, a 2-ethylhexyl group, and a phenyl group are preferred, and a methyl group, an ethyl group, a heptyl group, and a 2-ethylhexyl group are particularly preferred.

[0035] Examples of the carbonate salt (1) include 1,3-di-tert-butylimidazolium hydrogen carbonate, 1,3-bis(1,1-dimethylpropyl)imidazolium hydrogen carbonate, 1,3-bis(1,1,3,3-tetramethylbutyl)imidazolium hydrogen carbonate, 1,3-bis(1-methyl-1-phenylethyl)imidazolium hydrogen carbonate, 1,3-bis(1,1-dimethyl-2-phenylethyl)imidazolium hydrogen carbonate, and 1,3-bis(1-adamantyl)imidazolium hydrogen carbonate;

[0036] 1,3-di-tert-butylimidazolium methyl carbonate salt, 1,3-bis(1,1-dimethylpropyl)imidazolium methyl carbonate salt, 1,3-bis(1,1,3,3-tetramethylbutyl)imidazolium methyl carbonate salt, 1,3-bis(1-methyl-1-phenylethyl)imidazolium methyl carbonate salt, 1,3-bis(1,1-dimethyl-2-phenylethyl)imidazolium methyl carbonate salt, 1,3-bis(1-adamantyl)imidazolium methyl carbonate salt;

[0037] Examples of the benzimidazolium hydrogen carbonate salt include 1,3-di-tert-butyl benzimidazolium hydrogen carbonate salt, 1,3-bis(1,1,3,3-tetramethylbutyl) benzimidazolium methyl carbonate salt, and 1,3-bis(1,1,3,3-tetramethylbutyl) benzimidazolium methyl carbonate salt. Preferred are 1,3-di-tert-butylimidazolium hydrogen carbonate, 1,3-bis(1,1,3,3-tetramethylbutyl)imidazolium hydrogen carbonate, 1,3-di-tert-butylimidazolium methyl carbonate, and 1,3-bis(1,1,3,3-tetramethylbutyl)imidazolium methyl carbonate. More preferred are 1,3-bis(1,1,3,3-tetramethylbutyl)imidazolium hydrogen carbonate and 1,3-bis(1,1,3,3-tetramethylbutyl)imidazolium methyl carbonate.

[0038] The carbonate salt (1) may be a commercially available product or may be produced by a known method. For example, the carbonate salt (1) produced by the following production method A or production method B may also be used. <Production Method A and Production Method B>

[0039] The carbonate salt (1) can be obtained by reacting a salt represented by the following formula (5) (hereinafter referred to as salt (5)) with an alkali metal hydrogencarbonate represented by the following formula (6) (hereinafter referred to as alkali metal hydrogencarbonate (6)) or a carbonate ester represented by the following formula (7) (hereinafter referred to as carbonate ester (7)). Formula (5):

[0040] [ka] (In the formula, Y - is a halogen ion or the following formula (8b - ) represents the carboxylate anion. 1 , R 2 , R 3 , R 4 , R 5 , R6 , R 7 and R 8 is as defined above.) Formula (8b - ):

[0041] R 14 COO - (8b - ) (In the formula, R 14 represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. Formula (6):

[0042] HCO3·M (6) (In the formula, M represents an alkali metal atom.) Formula (7):

[0043] [ka] (In the formula, R 15 , R 16 are the same or different and represent a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom.

[0044] The salt (5) is preferably a salt represented by formula (5-1) (hereinafter referred to as salt (5-1)), and more preferably a salt represented by formula (5-2) (hereinafter referred to as salt (5-2)) or a salt represented by formula (5-3) (hereinafter referred to as salt (5-3)). Formula (5-1):

[0045] [ka] (In the formula, R 1 , R 2 , R 3 , R 6 , R 7 , R 8 , L and Y - are each as defined above.) Formula (5-2):

[0046] [ka] (In the formula, R 1 , R 2 , R 3 , R 6 , R 7 , R 8 , R 10 , R 11 and Y - are each as defined above.)

[0047] [ka] (In the formula, R 1 , R 2 , R 3 , R 6 , R 7 , R 8 , R 12 , R 13 and Y - are each as defined above.)

[0048] Formula (8b - ), R 14 is a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, and is preferably a hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a heteroatom. The hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a heteroatom is preferably a hydrocarbon group having 1 to 8 carbon atoms which may be substituted with a heteroatom, and particularly preferably a hydrocarbon group having 1 or 2 carbon atoms which may be substituted with a heteroatom.

[0049] In formula (6), M represents an alkali metal atom, and is preferably a sodium atom or a potassium atom.

[0050] Examples of the alkali metal hydrogen carbonate (6) include lithium hydrogen carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, rubidium hydrogen carbonate, and cesium hydrogen carbonate, and preferred are sodium hydrogen carbonate and potassium hydrogen carbonate.

[0051] In formula (7), R 15 , R16 represents a hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a heteroatom, is preferably a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a heteroatom, and is particularly preferably a hydrocarbon group having 1 to 8 carbon atoms which may be substituted with a heteroatom.

[0052] In formula (7), R 15 , R 16 Examples of the hydrocarbon group having 1 to 20 carbon atoms and optionally substituted with a heteroatom include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, an octyl group, a 1,1,3,3-tetramethylbutyl group, a 2-ethylhexyl group, a decyl group, a dodecyl group, a tetradecyl group, a hexadecyl group, an octadecyl group, an allyl group, a benzyl group, a cyclohexyl group, an adamantyl group, a phenyl group, a 2,6-diisopropylphenyl group, a 2,4,6-trimethylphenyl group, a 2-methoxyethyl group, a 2-ethoxyethyl group, a 2-(dimethylamino)ethyl group, etc. Preferred are a methyl group, an ethyl group, a propyl group, and a butyl group, and particularly preferred is a methyl group.

[0053] R 15 , R 16 In the above, examples of the heteroatom include a nitrogen atom, an oxygen atom, and a sulfur atom. When the hydrocarbon group is substituted with a heteroatom such as an oxygen atom, a nitrogen atom, or a sulfur atom, the hydrocarbon group has a group such as -O-, -N<, -S-, or -SO2-, and the hydrocarbon chain is interrupted by these groups. When the hydrocarbon group is substituted with a heteroatom such as an oxygen atom, a nitrogen atom, or a sulfur atom, it is preferable that the hydrocarbon group is substituted with an oxygen atom and the hydrocarbon chain is interrupted by an -O- group.

[0054] Specific examples of the carbonate ester (7) include dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, dipentyl carbonate, and dihexyl carbonate, and alkylene carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate. Preferred are dimethyl carbonate, diethyl carbonate, dipropyl carbonate, and dibutyl carbonate, and particularly preferred is dimethyl carbonate.

[0055] In formula (1), R 9 When producing a compound in which = hydrogen atom (hereinafter referred to as carbonate salt (1A)), one produced by the following production method A can also be used. <Manufacturing method A> In formula (5), Y - A halide represented by the following formula (5A), in which R is a halogen ion (hereinafter referred to as halide (5A)), is reacted with an alkali metal hydrogen carbonate (6) to obtain a carbonate salt (1A). Formula (1A):

[0056] [ka] (In the formula, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each as defined above.) Formula (5A):

[0057] [ka] (In the formula, X - R indicates a halogen ion. 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each as defined above.)

[0058] In formula (1), R 9 When producing a compound in which = a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom (hereinafter referred to as carbonate salt (1B)), one produced by the following production method B can also be used. <Manufacturing method B> Y - Formula (8b - ) (hereinafter, carboxylate anion (8b - ) is reacted with a carbonate ester (7) to obtain a compound represented by the following formula (1B 1 ) (hereinafter, carbonate salt (1B 1 ) or the following formula (1B 2 ) (hereinafter, carbonate salt (1B 2 ) can be produced. Carbonate salt (1B 1 ) and carbonate salt (1B 2 ) is included in the carbonate salt (1B). Formula (5B):

[0059] [ka] (In the formula, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 and R 14 are each as defined above.) Formula (1B 1 ):

[0060] [ka] (In the formula, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R7 , R 8 and R 15 are each as defined above.) Formula (1B 2 ):

[0061] [ka] (In the formula, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 and R 16 are each as defined above.)

[0062] The manufacturing method A will be described. In formula (5A), X - represents a halogen ion. Examples of the halogen ion include a fluorine ion, a chloride ion, a bromide ion, and an iodine ion, and preferably a chloride ion or a bromide ion, and more preferably a chloride ion.

[0063] The amount of the alkali metal hydrogen carbonate (6) used is usually 0.5 mol or more, preferably 0.8 to 5 mol, per mol of the halide (5A).

[0064] In production method A, the optimum reaction temperature varies depending on the starting materials, solvent, etc. used, but is usually -10°C or higher, and preferably 0°C to 100°C.

[0065] A solvent may or may not be used. When a solvent is used, the solvent to be used is not particularly limited as long as it 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, and preferably alcohol solvents and water, and particularly preferably 2-propanol. Two or more types of solvents can be mixed and used as needed.

[0066] The amount of the solvent used is usually 50 parts by mass or less, and preferably 0.1 to 10 parts by mass, per part by mass of the halide (5A).

[0067] If necessary, the reaction may be carried out in an atmosphere of an inert gas such as nitrogen, argon, or helium that does not affect the reaction.

[0068] After the reaction is completed, the carbonate salt (1A) can be isolated by removing inorganic salts (alkali metal halides) by filtration, removing impurities by replacing the reaction solution with an aqueous solution and then washing with an organic solvent, concentrating the reaction solution, etc., and may be purified by recrystallization, etc., if necessary. The carbonate salt (1A) can also be reacted with a carbonate ester (7) without being extracted from the reaction solution to obtain the carbonate salt (1B). In addition, the carbonate salt (1A) can be used as the carbonate compound (1A) for producing the carbene compound (2) by replacing the carbonate salt (1A) with a solution suitable for producing the carbene compound (2) without extracting it from the reaction solution or the aqueous solution after washing.

[0069] The manufacturing method B will now be described. The amount of carbonate (7) used is usually 1 mole or more per mole of carboxylate (5B), and since carbonate (7) can also be used as a reaction solvent, it is preferably 1 to 1000 moles, more preferably 1 to 6 moles. When excess carboxylic acid and water are contained in the carboxylate (5B), they react with the carbonate (7), so it is preferable to use the carbonate (7) in an excess of usually 1 mole or more, preferably 1 to 6 moles, per mole of the total of the excess carboxylic acid and water in the carboxylate (5B). The carbonate (7) can also be used as a solvent by using it in excess relative to the carboxylate (5B).

[0070] In production method B, the optimum reaction temperature varies depending on the starting materials, solvent, etc. used, but is usually -10°C or higher, and preferably 0°C to 150°C.

[0071] A solvent may or may not be used. When a solvent is used, the solvent that can be used other than the carbonate ester (7) as the solvent is not particularly limited as long as it does not affect the reaction. Specific examples of the solvent other than the carbonate ester (7) include aromatic hydrocarbon solvents such as toluene, benzene, xylene, etc., halogenated aromatic hydrocarbon solvents such as chlorobenzene, dichlorobenzene, etc., hydrocarbon solvents such as methylcyclohexane, cyclohexane, hexane, heptane, octane, etc., halogenated hydrocarbon solvents such as dichloromethane, chloroform, etc., ether solvents such as diethyl ether, tetrahydrofuran, 1,4-dioxane, etc., alcohol solvents such as methanol, ethanol, etc., N,N-dimethylformamide, acetonitrile, etc., and aromatic hydrocarbon solvents and alcohol solvents are preferred. Two or more types of solvents can also be mixed and used as necessary.

[0072] The amount of the solvent used is usually 50 parts by mass or less, and preferably 0.1 to 10 parts by mass, per part by mass of the carboxylate (5B). If necessary, the reaction may be carried out in an atmosphere of an inert gas such as nitrogen, argon, or helium that does not affect the reaction.

[0073] After the reaction is completed, the carbonate salt (1B) can be isolated by removing impurities by washing with an organic solvent, concentrating the reaction solution, etc., and may be purified by recrystallization, etc., if necessary. Alternatively, the carbene compound (2) can be produced continuously by replacing the carbonate salt (1B) with a solution suitable for producing the carbene compound (2) without taking out the carbonate salt (1B) from the reaction solution or the filtrate after washing. As the organic solvent used for removing impurities by washing, aromatic hydrocarbon solvents such as toluene, benzene and xylene are preferred, with toluene being particularly preferred.

[0074] As a method for producing the carbonate salt (1B) other than the production method B, there can be mentioned a method for producing the carbonate salt (1B) by reacting the carbonate salt (1A) obtained by the production method A with a carbonate ester (7).

[0075] In the production method A and the production method B, the halide (5A) or the carboxylate (5B) may be a commercially available product, or may be obtained by a known method. When the salt (5) is a compound represented by formula (5-2), i.e., when the halide (5A) is a halide represented by the following formula (5-2A) (hereinafter referred to as halide (5-2A)), and when the carboxylate (5B) is a carboxylate represented by the following formula (5-2B) (hereinafter referred to as carboxylate (5-2B)), for example, one produced by the following production method C can also be used. Formula (5-2A):

[0076] [ka] (In the formula, X - R indicates a halogen ion. 1 , R 2 , R 3 , R 6 , R 7 , R 8 , R 10 and R 11 are each as defined above.) Formula (5-2B):

[0077] [ka] (In the formula, R 1 , R 2 , R 3 , R 6 , R 7 , R 8 , R 10 , R 11 and R 14 are each as defined above.)

[0078] <Manufacturing method C> A dicarbonyl compound represented by the following formula (9) (hereinafter referred to as dicarbonyl compound (9)), a primary amine compound represented by the following formula (10a) (hereinafter referred to as primary amine compound (10a)), a primary amine compound represented by the following formula (10b) (hereinafter referred to as primary amine compound (10b)), formaldehyde, a hydrogen halide represented by formula (8a) (hereinafter referred to as hydrogen halide (8a)), or a carboxylic acid represented by formula (8b) (hereinafter referred to as carboxylic acid (8b)) are reacted to obtain a halide (5-2A) or a carboxylate (5-2B). Formula (9):

[0079] [ka] (In the formula, R 10 and R 11 is as defined above.) Formula (10a):

[0080] R 1 R 2 R 3 C-NH2(10a) (In the formula, R 1 , R 2 and R 3 is as defined above.) Formula (10b):

[0081] R 6 R7 R 8 C-NH2(10b) (In the formula, R 6 , R 7 and R 8 is as defined above.) Formula (8a): HX (8a) (In the formula, X represents a halogen atom.) Formula (8b): R 14 COOH (8b) (In the formula, R 14 is as defined above.)

[0082] The manufacturing method C will now be described. In formula (5-2A), X - represents a halogen ion. Examples of the halogen ion include a fluorine ion, a chloride ion, a bromide ion, and an iodine ion, and preferably a chloride ion or a bromide ion, and more preferably a chloride ion.

[0083] Examples of the halide (5-2A) include 1,3-di-tert-butylimidazolium chloride, 1,3-bis(1,1-dimethylpropyl)imidazolium chloride, 1,3-bis(1,1,3,3-tetramethylbutyl)imidazolium chloride, 1,3-bis(1-methyl-1-phenylethyl)imidazolium chloride, 1,3-bis(1,1-dimethyl-2-phenylethyl)imidazolium chloride, and 1,3-bis(1-adamantyl)imidazolium chloride;

[0084] 1,3-di-tert-butylimidazolium bromide, 1,3-bis(1,1-dimethylpropyl)imidazolium bromide, 1,3-bis(1,1,3,3-tetramethylbutyl)imidazolium bromide, 1,3-bis(1-methyl-1-phenylethyl)imidazolium bromide, 1,3-bis(1,1-dimethyl-2-phenylethyl)imidazolium bromide, 1,3-bis(1-adamantyl)imidazolium bromide;

[0085] Examples of the compound include 1,3-di-tert-butylbenzimidazolium chloride, 1,3-bis(1,1,3,3-tetramethylbutyl)benzimidazolium chloride, 1,3-di-tert-butylbenzimidazolium bromide, and 1,3-bis(1,1,3,3-tetramethylbutyl)benzimidazolium bromide. Preferred are 1,3-di-tert-butylimidazolium chloride and 1,3-bis(1,1,3,3-tetramethylbutyl)imidazolium chloride.

[0086] Examples of the carboxylate (5-2B) include 1,3-di-tert-butylimidazolium formate, 1,3-bis(1,1-dimethylpropyl)imidazolium formate, 1,3-bis(1,1,3,3-tetramethylbutyl)imidazolium formate, 1,3-bis(1-methyl-1-phenylethyl)imidazolium formate, 1,3-bis(1,1-dimethyl-2-phenylethyl)imidazolium formate, and 1,3-bis(1-adamantyl)imidazolium formate;

[0087] 1,3-Di-tert-butylimidazolium acetate, 1,3-bis(1,1-dimethylpropyl)imidazolium acetate, 1,3-bis(1,1,3,3-tetramethylbutyl)imidazolium acetate, 1,3-bis(1-methyl-1-phenylethyl)imidazolium acetate, 1,3-bis(1,1-dimethyl-2-phenylethyl)imidazolium acetate, 1,3-bis(1-adamantyl)imidazolium acetate;

[0088] Examples of the compound include 1,3-di-tert-butylbenzimidazolium formate, 1,3-bis(1,1,3,3-tetramethylbutyl)benzimidazolium formate, 1,3-di-tert-butylbenzimidazolium acetate, and 1,3-bis(1,1,3,3-tetramethylbutyl)benzimidazolium acetate. Preferred are 1,3-di-tert-butylimidazolium acetate and 1,3-bis(1,1,3,3-tetramethylbutyl)imidazolium acetate.

[0089] Examples of the dicarbonyl compound (9) include glyoxal, 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, and are preferably glyoxal or diacetyl, and more preferably glyoxal.

[0090] The primary amine compound (10a) and the primary amine compound (10b) are at least one primary amine compound selected from the group consisting of tert-butylamine, 1,1-dimethylethylamine, 1,1-dimethylpropylamine, cumylamine, 1,1,3,3-tetramethylbutylamine, 1,1-dimethyl-2-phenylethylamine, and 1-adamantylamine, preferably tert-butylamine, 1,1,3,3-tetramethylbutylamine, cumylamine, and 1-adamantylamine, and more preferably tert-butylamine and 1,1,3,3-tetramethylbutylamine.

[0091] The dicarbonyl compound (9) may be used as it is in the form of an aqueous solution or an alcohol solution such as methanol or butanol. The amount of the primary amine compound (10a) and the primary amine compound (10b) (hereinafter, the primary amine compound (10a) and the primary amine compound (10b) are collectively referred to as the amine compound (10)) to be used is usually 0.1 to 10 mol, and preferably 1 to 3 mol, of the total amount of the primary amine compound (10a) and the primary amine compound (10b) per 1 mol of the dicarbonyl compound (9).

[0092] The ratio of the primary amine compound (10a) to the primary amine compound (10b) is not particularly limited, and is in the range of primary amine compound (10a):primary amine compound (10b)=0:100 to 100:0. When the primary amine compound (10a):primary amine compound (10b)=0:100 or primary amine compound (10a):primary amine compound (10b)=100:0, R 1 R2 R 3 C=R 6 R 7 R 8 C. Even when the ratio of the primary amine compound (10a):primary amine compound (10b) is 1:1, the compound of formula (1) is (R 1 R 2 R 3 C, R 1 R 2 R 3 C), (R 1 R 2 R 3 C, R 6 R 7 R 8 C), (R 6 R 7 R 8 C, R 6 R 7 R 8 C), and when the ratio of the primary amine compound (10a):primary amine compound (10b) is 0:100 to 100:0, (R 1 R 2 R 3 C, R 1 R 2 R 3 C), (R 1 R 2 R 3 C, R 6 R 7 R 8 C), (R 6 R 7 R 8 C, R 6 R 7 R 8 C) The ratios of the three combinations are different, and these three types are R 1 , R 2 , R 3 , R 6 , R 7 and R 8 may be the same or different and are included in the compounds of formula (5-2A) or formula (5-2B).

[0093] Formaldehyde may be used as it is in the form of an aqueous solution or an alcohol solution such as methanol, butanol, etc. The amount of formaldehyde used is usually 0.1 to 10 mol, preferably 0.5 to 5.0 mol, per mol of the dicarbonyl compound (8).

[0094] In formula (8a), X represents a halogen atom. Examples of the halogen atom include a fluorine atom, a bromine atom, a chlorine atom, and an iodine atom. Of these, a bromine atom and a chlorine atom are preferred, and a chlorine atom is particularly preferred. Examples of the hydrogen halide (8a) include hydrogen fluoride, hydrogen bromide, hydrogen chloride, and hydrogen iodide, with hydrogen bromide and hydrogen chloride being preferred, and hydrogen chloride being particularly preferred.

[0095] Carboxylic acids (8b) include formic acid, acetic acid, propionic acid, butyric acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, 2-ethylhexanoic acid, capric acid, lauric acid, tetradecylic acid, palmitic acid, octadecylic acid, cyclohexanoic acid, ethoxyacetic acid, propoxyacetic acid, 2-(2-methoxyethoxy)acetic acid, 2-(2-ethoxyethoxy)acetic acid, 2-(2-propoxyethoxy)acetic acid, 3-methoxypropanoic acid, 3-ethoxypropanoic acid, 3-(2-methoxyethoxy)propanoic acid, 3-(2-ethoxyethoxy) Examples of carboxylic acids include propanoic acid, 3-(2-propoxyethoxy)propanoic acid, 3-(3-methoxypropoxy)propanoic acid, 3-(3-ethoxypropoxy)propanoic acid, 3-(3-propoxypropoxy)propanoic acid, oleic acid, linoleic acid, sorbic acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, lactic acid, salicylic acid, and trifluoroacetic acid. Preferred are formic acid, acetic acid, propionic acid, butyric acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, and 2-ethylhexanoic acid, and more preferred is acetic acid.

[0096] The hydrogen halide (8a) or the carboxylic acid (8b) (hereinafter, the hydrogen halide (8a) and the carboxylic acid (8b) are collectively referred to as the acid (8)) can be used as it is, or in the form of an aqueous solution or an alcohol solution such as methanol or butanol. In the production method C, when a hydrogen halide (8a) is used as the acid (8), the amount of the acid used is usually 0.1 to 10 mol, preferably 0.5 to 5 mol, and more preferably 0.8 to 1.5 mol, per mol of the dicarbonyl compound (9). When a carboxylic acid (8b) is used as the acid (8), the amount of the acid used is usually 0.1 to 10 mol, preferably 0.5 to 5 mol, and more preferably 0.8 to 3 mol, per mol of the dicarbonyl compound (9).

[0097] In the production method C, when a hydrogen halide (8a) is used as the acid (8), a halide (5-2A) can be produced. When a carboxylic acid (8b) is used as the acid (8), a carboxylate (5-2B) can be produced. The optimum reaction temperature varies depending on the starting materials, solvent, etc. used, but is usually -10°C or higher, preferably 0°C to 100°C.

[0098] A solvent may or may not be used. When a solvent is used, the solvent to be used is not particularly limited as long as it 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 and ethanol, N,N-dimethylformamide, acetonitrile, and water, and preferably aromatic hydrocarbon solvents, alcohol solvents, and water, and particularly preferably toluene and water. Two or more types of solvents can be mixed and used as needed.

[0099] The amount of the solvent used is usually 50 parts by mass or less, and preferably 0.1 to 10 parts by mass, per part by mass of the dicarbonyl compound (9). If necessary, the reaction may be carried out in an atmosphere of an inert gas such as nitrogen, argon, or helium that does not affect the reaction.

[0100] After the reaction is completed, the halide (5-2A) or carboxylate (5-2B) can be isolated by removing low-boiling impurities by concentration or the like. The obtained halide (5-2A) or carboxylate (5-2B) may be washed with an organic solvent such as diethyl ether to remove impurities (e.g., unreacted raw materials). The impurities may be removed by replacing the solvent in the reaction solution with an aqueous solution and then washing with an organic solvent. When the unreacted amine compound (10) reacts with the acid (8) to obtain an ammonium salt, it is possible to neutralize the ammonium salt with an alkaline compound such as sodium bicarbonate, and remove the solid inorganic salt by filtration. The obtained halide (5-2A) or carboxylate (5-2B) may be purified by recrystallization or the like, if necessary. After completion of the reaction, the reaction solution may be used as the halide (5-2A) in Production Method A without being extracted from the reaction solution. The reaction solution may be used as the carboxylate (5B) in Production Method B without being extracted from the reaction solution. In the production method B, the carboxylate (5B) may be, for example, that produced by the following production method D. <Manufacturing method D> The carbonate salt (1A) is reacted with a carboxylic acid (8b) to give the carboxylate salt (5B).

[0101] The manufacturing method D will now be described. In the production method D, the carbonate salt (1A) may be a commercially available product or may be produced by a known method. The carbonate salt (1A) produced by the above-mentioned production method A may also be used. When the carbonate salt (1A) produced by the above-mentioned production method A is used, the carbonate salt (1A) may be used as the reaction solution in the production method D without being isolated from the reaction solution after the reaction described in the production method A.

[0102] In production method D, the carboxylic acid (8b) is preferably acetic acid. The carboxylic acid (8b) may be used as it is, or may be used in the form of an aqueous solution or an alcohol solution such as methanol or butanol. The amount of the acid used is usually 0.1 to 10 mol, preferably 0.5 to 5 mol, and more preferably 0.8 to 1.5 mol, per mol of the carbonate salt (1A).

[0103] A solvent may or may not be used. When a solvent is used, the solvent to be used is not particularly limited as long as it 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 and ethanol, N,N-dimethylformamide, acetonitrile, and water, among which alcohol solvents and water are preferred, and methanol is particularly preferred. Two or more types of solvents can also be mixed and used as needed.

[0104] The amount of the solvent used is usually 50 parts by mass or less, and preferably 0.1 to 10 parts by mass, per part by mass of the carbonate salt (1A). If necessary, the reaction may be carried out in an atmosphere of an inert gas such as nitrogen, argon, or helium that does not affect the reaction.

[0105] After the reaction is completed, the carboxylate (5B) can be isolated by removing low-boiling impurities by concentration or the like. The obtained carboxylate (5B) may be washed with an organic solvent to remove impurities. The obtained carboxylate (5B) may be purified by recrystallization or the like, if necessary. Moreover, the resulting carboxylate (5B) can also be used as a raw material in Production Method B without being extracted from the reaction mixture.

[0106] The carbene compound (2) will be described. In formula (2), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each as defined above. R 1 and R 2 , R 2 and R 3 , R 6 and R 7 , or R 7 and R 8 may form a ring structure together with the carbon atom to which they are attached. 4 and R 5 may form a ring structure together with the nitrogen atom to which they are attached.

[0107] The carbene compound (2) is preferably a carbene compound represented by formula (2-1) (hereinafter referred to as carbene compound (2-1)), and more preferably a carbene compound represented by formula (2-2) (hereinafter referred to as carbene compound (2-2)) or a carbene compound represented by formula (2-3) (hereinafter referred to as carbene compound (2-3)). Formula (2-1):

[0108] [ka] (In the formula, R 1 , R 2 , R 3 , R6 , R 7 , R 8 and L are each as defined above. Formula (2-2):

[0109] [ka] (In the formula, R 1 , R 2 , R 3 , R 6 , R 7 , R 8 , R 10 and R 11 are each as defined above.) Formula (2-3):

[0110] [ka] (In the formula, R 1 , R 2 , R 3 , R 6 , R 7 , R 8 , R 12 and R 13 Each is as defined above.)

[0111] In formula (2-2), R 10 and R 11 may form a ring structure together with the carbon atom to which they are attached. 10 and R 11 However, when they form a ring structure together with the carbon atom to which they are attached, they can take the form of, for example, a benzimidazolium ring structure as shown in the following formula (2-2x). Formula (2-2x):

[0112] [ka] (In the formula, R 1 , R 2 , R 3 , R 6 , R 7 , R 8, R w , R x , R y and R z is as defined above.)

[0113] In formula (2-2x), R w , R x , R y or R z Examples of the hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a 1-ethylpentyl group, a nonyl group, a 2-ethylhexyl group, an undecyl group, a tridecyl group, a pentadecyl group, a heptadecyl group, a vinyl group, an allyl group, a benzyl group, a cyclohexyl group, an adamantyl group, a phenyl group, a 2-methoxymethyl group, a 2-ethoxymethyl group, a 2-(dimethylamino)methyl group, and the like. Of these, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a heptyl group, a cyclohexyl group, a 2-ethylhexyl group, and a phenyl group are preferred, and a methyl group, an ethyl group, a heptyl group, and a 2-ethylhexyl group are particularly preferred.

[0114] Specific examples of the carbene compound (2) are shown below. However, the present invention is not limited to these. In the following specific examples, Et represents an ethyl group, Np represents a neopentyl group, Ph represents a phenyl group, and Bnz represents a benzyl group.

[0115] [ka]

[0116] [ka]

[0117] The carbene compound (2) is preferably a compound represented by formula (2-2-2) to formula (2-2-5), and particularly preferably a compound represented by (2-2-3). EXAMPLES

[0118] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. 1 H-NMR was measured at 400 MHz using AV400 manufactured by Bruker Corp. In the examples, wt% indicates a mass percent concentration.

[0119] In the examples, the chlorine concentration was measured by the following method. Chlorine concentration test method: Ion Chromatography IC device: Thermo Fisher Scientific ICS-1100 Column: AS9-HC / AG9HC Column temperature: 30℃ Elution: 2.3 mM sodium carbonate + 2.8 mM sodium bicarbonate solution Flow rate: 1.0 mL per minute Current value: 25mA Injection volume: 25μL [DtOI][HCO3] (100 mg) was diluted to 10 mL with a mixture of 2-propanol / water (8 / 2). The production scheme of the examples is shown below.

[0120] [ka] Manufacturing method C (Method C, solid line) corresponds to Manufacturing Example 1. Manufacturing method A corresponds to Manufacturing Example 2. Manufacturing method D+B corresponds to Manufacturing Example 3. While manufacturing method C is limited to those having an imidazolium ring structure, manufacturing methods A, B, and D are not limited to those having an imidazolium ring structure because they are ion exchange reactions. Production Example 1 Synthesis of [DtOI][Cl]

[0121] [ka] In a 200mL three-necked reactor purged with nitrogen, 7.7g (77mmol) of 35% aqueous hydrochloric acid, 6.2g (85mmol) of 41wt% aqueous formalin, and 12.1g (85mmol) of 40wt% aqueous glyoxal were charged and heated to 40°C. Next, 20g (154mmol) of 1,1,3,3-tetramethylbutylamine was added dropwise to the mixture in the three-necked reactor at 40°C over 15 minutes, and the mixture was heated to 70°C during the dropwise addition and stirred for 22 hours. After that, after cooling to room temperature, 200mL of 0.5M aqueous sodium hydrogen carbonate was added and further stirred at room temperature for 30 minutes. The resulting reaction solution was transferred to a separatory funnel, 100mL of diethyl ether was added, and after shaking, the aqueous layer and the upper layer were separated, and the lower layer was transferred to a separatory funnel again, 100mL of diethyl ether was added, and the aqueous layer obtained by the same operation was concentrated under reduced pressure to obtain a yellowish brown solid. To the obtained solid, 200 mL of dichloromethane was added, and the mixture was stirred at room temperature for 30 minutes. The filtrate obtained by filtration under reduced pressure using a perlite-precoated Nutsche funnel was concentrated under reduced pressure to obtain 12.0 g (36 mmol, 47% yield) of [DtOI][Cl] represented by the above formula. [DtOI][Cl] 1 The H-NMR analysis results are shown below. 1 H-NMR(CD3OD)δ(ppm)=0.8(18H, s), 1.77(12H, s), 2.03(4H, s), 7.96(2H, d, J=1.6Hz), 9.16-9.18(1H, m) Production Example 2 Synthesis of [DtOI][HCO3]

[0122] [ka] In a test tube, 1.0 g (3.0 mmol) of [DtOI][Cl] obtained in Production Example 1, 310 mg (3.1 mmol) of potassium hydrogen carbonate, and 5.2 g of 2-propanol were charged and stirred at 80°C for 7 hours. After stirring, the reaction solution was cooled to room temperature and further stirred at room temperature for 63 hours. The reaction mixture was then filtered through a 0.2 μm membrane filter, and the filtrate was concentrated to obtain 1.1 g (3.1 mmol, 99% yield) of [DtOI][HCO3] represented by the above formula. [DtOI][HCO3]1 The H-NMR analysis results and chloride ion concentration are shown below. 1 H-NMR(CD3OD)δ(ppm)=7.98(2H,s), 2.03(4H,s), 1.76(12H,s), 0.88(18H,s) Chloride ion concentration: 176 ppm Production Example 3 Synthesis of [DtOI][MeCO3]

[0123] [ka] In a 200mL three-necked reactor, 10.0g (28.2mmol) of [DtOI][HCO3] obtained by the same procedure as in Production Example 2, 1.86g (31.0mmol), and 15.2g of methanol were charged and stirred at room temperature for 65 hours under a nitrogen stream. The resulting reaction solution was concentrated under reduced pressure to obtain 9.97g of a pale yellow solid. Then, 7.44g (82.6mmol) of dimethyl carbonate was added and the mixture was heated and refluxed at 110°C for 42 hours. The resulting reaction solution was concentrated under reduced pressure to obtain 9.80g of a dark brown solid. 50mL of toluene was added to the dark brown solid, and the mixture was stirred at room temperature for 30 minutes and then filtered to obtain 5.49g (14.9mmol, 52.8% yield) of [DtOI][MeCO3] represented by the above formula as a pale yellow solid. [DtOI][MeCO3] 1 The H-NMR analysis results are shown below. 1 H-NMR(CDCl3)δ(ppm)=7.43(2H,s), 3.55(3H,s), 2.04(4H,s), 1.80(12H,s), 0.86(18H,s) Example 1: Preparation of DtBI

[0124] [ka] In a 15 mL test tube equipped with an air-cooling tube, 55.7 mg (230 μmol) of 1,3-di-tert-butylimidazolium hydrogen carbonate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 6.5 g of toluene were added, and after replacing with nitrogen, the mixture was heated under reflux for 3 hours. The resulting reaction solution was concentrated under reduced pressure to obtain 30.5 mg (169 μmol, 73.5% yield) of DtBI represented by the above formula. 1 The H-NMR analysis results are shown below. 1 H-NMR(Toluene-d8)δ(ppm)=6.70(2H,s), 1.44(18H,s) 13 C-NMR(Toluene-d8)δ(ppm)=212.1, 114.9, 55.8, 31.4 Example 2 Preparation of DtOI

[0125] [ka] In a 15 mL test tube equipped with an air-cooling tube, 0.51 g (1.4 μmol) of [DtOI][HCO3] obtained in Production Example 2 and 5.45 g of toluene were added, and after replacing the atmosphere with nitrogen, the mixture was heated under reflux for 6 hours. The reaction mixture was filtered through a 0.2 μm membrane filter, and the filtrate was concentrated to obtain 0.05 g (0.2 μmol, 11.9% yield) of DtOI represented by the above formula. 1 The H-NMR analysis results are shown below. 1 H-NMR(C6D6)δ(ppm)=6.74(2H,s), 1.87(4H,s), 1.58(12H,s), 0.85(18H,s) 13 C-NMR(C6D6)δ(ppm)=212.3, 115.8, 59.4, 55.4, 31.9, 31.7, 31.3

[0126] Example 3 Preparation of DtOI In a 100 mL test tube equipped with an air-cooling tube, 5 g (13.6 mmol) of [DtOI][MeCO3] obtained in Production Example 3 and 25 g of chlorobenzene were added, and the mixture was heated under reflux for 4 hours after replacing with nitrogen. The reaction mixture was filtered through a 0.2 μm membrane filter, and the filtrate was concentrated to obtain 1.8 g (6.3 mmol, 46.2% yield) of DtOI.

[0127] Comparative Example 1 In a 15 mL test tube equipped with an air-cooled tube and a Dean-Stark trap, 0.2 g (1.4 mmol) of 1,3-dimethylimidazolium-2-carboxylate manufactured by Tokyo Chemical Industry Co., Ltd. and 0.25 g (13.9 mmol) of water were added and stirred to obtain a homogeneous solution. 1 H-NMR analysis confirmed that 1,3-dimethylimidazolium hydrogen carbonate was obtained. 1 The H-NMR analysis results are shown below. 1 H-NMR(CD3OD)δ(ppm)=7.55(2H,s), 3.92(6H,s) Next, 8.0 g of toluene was added to the obtained solution, and the mixture was purged with nitrogen, after which water was azeotropically removed at 85° C. and the mixture was heated to reflux for 5 hours. The obtained reaction mixture was concentrated, 1 Analysis by H-NMR revealed that no carbene compound was obtained, and it was confirmed that the product was a mixture of 1,3-dimethylimidazolium hydrogen carbonate and 1,3-dimethylimidazolium-2-carboxylate.

Claims

1. A method for producing a carbene compound represented by the following formula (2), comprising heating a carbonate salt represented by the following formula (1) in a solvent. Formula (1): 【Chemistry 1】 (In the formula, R １ , R ２ , R ３ , R ４ , R ５ , R ６ , R ７ and R ８ R may be the same or different and represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. １ and R ２ , R ２ and R ３ , R ６ and R ７ , or R ７ and R ８ may form a ring structure together with the carbon atom to which they are attached. ４ and R ５ may form a ring structure together with the nitrogen atom to which they are attached. １ R ２ R ３ or a group represented by CR ６ R ７ R ８ The group represented by may be an adamantyl group. ９ represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. Formula (2): 【Chemistry 2】 (In the formula, R １ , R ２ , R ３ , R ４ , R ５ , R ６ , R ７ and R ８ are each as defined above.)

2. The method for producing the carbene compound according to claim 1, comprising heating the solvent to a temperature higher than the boiling point of water, the boiling point of the solvent being higher than the boiling point of water.

3. The method for producing a carbene compound according to claim 1 or 2, wherein the reaction temperature is 40 to 200° C.

4. The method for producing a carbene compound according to any one of claims 1 to 3, wherein the carbonate salt represented by formula (1) is a carbonate salt represented by the following formula (1-1): Formula (1-1): 【Chemistry 3】 (In the formula, R １ , R ２ , R ３ , R ６ , R ７ , R ８ and R ９ are as defined above. L represents a bridged structure having 2 to 40 carbon atoms linking nitrogen atoms together, which may have a double bond, a monocyclic structure or a condensed ring structure, or a substituent.

5. The method for producing a carbene compound according to claim 4, wherein the carbonate salt represented by formula (1-1) is a carbonate salt represented by either formula (1-2) or formula (1-3): Formula (1-2): 【Chemistry 4】 (In the formula, R １ , R ２ , R ３ , R ６ , R ７ , R ８ and R ９ Each is as defined above. １０ and R １１ R may be the same or different and represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom. １０ and R １１ may form a ring structure together with the carbon atom to which they are attached.) Formula (1-3): 【Chemistry 5】 (In the formula, R １ , R ２ , R ３ , R ６ , R ７ , R ８ and R ９ Each is as defined above. １２ and R １３ R may be the same or different and represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom. １２ and R １３ may form a ring structure together with the carbon atom to which they are attached.)

6. R １ , R ２ , R ３ , R ６ , R ７ and R ８ and are the same or different and each is an alkyl group having 1 to 8 carbon atoms.

7. The method for producing a carbene compound according to any one of claims 1 to 6, wherein the solvent is an aromatic hydrocarbon solvent, an aliphatic or alicyclic hydrocarbon solvent, or a halogenated aromatic hydrocarbon solvent.

8. A carbene compound represented by the following formula (2): Formula (2): 【Chemistry 6】 (In the formula, R １ , R ２ , R ４ , R ５ , R ６ and R ７ R may be the same or different and represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. ３ and R ８ R may be the same or different and represents a hydrocarbon group having 2 to 20 carbon atoms which may contain a heteroatom. １ and R ２ , R ２ and R ３ , R ６ and R ７ , or R ７ and R ８ may form a ring structure together with the carbon atom to which they are attached. ４ and R ５ may form a ring structure together with the nitrogen atom to which they are attached.)

9. The carbene compound according to claim 8, represented by the following formula (2-1): Formula (2-1): 【Chemistry 7】 (In the formula, R １ , R ２ , R ３ , R ６ , R ７ and R ８ are as defined above. L represents a bridged structure having 2 to 40 carbon atoms linking nitrogen atoms together, which may have a double bond, a monocyclic structure or a condensed ring structure, or a substituent.

10. The carbene compound according to claim 8 or 9, represented by the following formula (2-2) or formula (2-3): Formula (2-2): 【Chemistry 8】 (In the formula, R １ , R ２ , R ３ , R ６ , R ７ and R ８ Each is as defined above. １０ and R １１ R may be the same or different and represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom. １０ and R １１ may form a ring structure together with the carbon atom to which they are attached.) Formula (2-3): 【Chemistry 9】 (In the formula, R １ , R ２ , R ３ , R ６ , R ７ and R ８ Each is as defined above. １２ and R １３ R may be the same or different and represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom. １２ and R １３ may form a ring structure together with the carbon atom to which they are attached.)

11. The carbene compound according to claim 8, represented by the following formula: 【Chemistry 10】

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