Catalyst reusage method, organic compound production method, and catalyst storage method

Abstract

A catalyst reusage method according to the present invention comprises: a first reaction step for causing a first starting compound to react by using a catalyst; a separation step for separating a catalyst solution containing the catalyst from a reaction liquid obtained in the first reaction step; a storage step for storing the catalyst solution in a pressurized atmosphere; and a second reaction step for causing a second starting compound to react by using the catalyst solution that has been stored. The catalyst is at least one selected from the group consisting of metal complexes each including a metal and a specific ligand, and salts thereof. The pressurized atmosphere is substantially formed of a gas other than oxygen.

Description

METHOD FOR REUSING CATALYST, METHOD FOR PRODUCING ORGANIC COMPOUND, AND METHOD FOR STORING CATALYST

[0001] The present invention relates to a method for reusing a catalyst, a method for producing an organic compound, and a method for storing a catalyst.

[0002] In organic synthesis, various reactions using transition metal complexes composed of transition metals and ligands as catalysts are known.

[0003] For example, due to issues such as global warming and the depletion of fossil fuels, there are high hopes for hydrogen energy as a next-generation energy source, and methods for producing formic acid from carbon dioxide (CO2) and hydrogen (H2) in the presence of a catalyst are being investigated.

[0004] Patent Document 1 describes a method for producing formic acid by reacting carbon dioxide with hydrogen in the presence of a catalyst containing an element from Group 8, 9 or 10 of the periodic table, a tertiary amine (I) and a polar solvent.

[0005] Patent No. 5734286

[0006] From a cost perspective, there is a demand for catalyst reuse. However, in conventional technologies, even if a catalyst has high activity at the start of the reaction, the catalyst deteriorates as the catalytic reaction progresses and over time, resulting in a decrease in the yield of the product.

[0007] Therefore, an object of the present invention is to provide a method for reusing a catalyst, a method for producing an organic compound, and a method for storing a catalyst that are suitable for reducing catalyst deterioration.

[0008] The present invention provides a method for recycling a catalyst, comprising: a first reaction step of reacting a first starting compound using a catalyst; a separation step of separating a catalyst solution containing the catalyst from a reaction liquid obtained in the first reaction step; a storage step of storing the catalyst solution under a pressurized atmosphere; and a second reaction step of reacting a second starting compound using the catalyst solution after storage, wherein the catalyst is at least one selected from the group consisting of metal complexes containing a metal M and a ligand represented by the following general formula (1B) and salts thereof, and the pressurized atmosphere consists essentially of a gas other than oxygen: (In general formula (1B), X represents an atomic group containing a typical element of Groups 13 to 15 that can be coordinated to the metal M; each Y independently represents an atomic group containing a typical element of Groups 14 to 16 that can be coordinated to the metal M; and each Q independently represents a bridge structure that connects Y and X and contains a typical element of Groups 14 to 16.)

[0009] The present invention further provides a method for producing an organic compound using the method for reusing a catalyst, the method including producing an organic compound from the first starting compound and producing an organic compound from the second starting compound.

[0010] The present invention further provides a method for storing a catalyst, comprising storing a catalyst solution containing a catalyst under a pressurized atmosphere, wherein the catalyst is at least one selected from the group consisting of metal complexes containing a metal M and a ligand represented by general formula (1B) above, and salts thereof, and the pressurized atmosphere consists essentially of a gas other than oxygen.

[0011] According to the present invention, it is possible to provide a method for reusing a catalyst, a method for producing an organic compound, and a method for storing a catalyst that are suitable for reducing catalyst deterioration.

[0012] Fig. 1 is a schematic diagram showing an example of a three-compartment electrodialysis apparatus. Fig. 2 is a schematic diagram showing an example of a formic acid production system. Fig. 3 is a diagram showing a schematic configuration of the apparatus used in Reference Examples 1 to 8. Fig. 4 is a diagram showing a schematic configuration of the apparatus used in Examples 4 to 10.

[0013] A catalyst recycling method according to a first aspect of the present invention includes: a first reaction step of reacting a first starting compound using a catalyst; a separation step of separating a catalyst solution containing the catalyst from a reaction liquid obtained in the first reaction step; a storage step of storing the catalyst solution under a pressurized atmosphere; and a second reaction step of reacting a second starting compound using the catalyst solution after storage, wherein the catalyst is at least one selected from the group consisting of metal complexes containing a metal M and a ligand represented by the following general formula (1B) and salts thereof, and the pressurized atmosphere consists essentially of a gas other than oxygen: (In general formula (1B), X represents an atomic group containing a typical element of Groups 13 to 15 that can be coordinated to the metal M; each Y independently represents an atomic group containing a typical element of Groups 14 to 16 that can be coordinated to the metal M; and each Q independently represents a bridge structure that connects Y and X and contains a typical element of Groups 14 to 16.)

[0014] In a second aspect of the present invention, for example, in the method for recycling a catalyst according to the first aspect, the gas contains at least one selected from the group consisting of hydrogen and nitrogen.

[0015] In a third aspect of the present invention, for example, in the catalyst recycling method according to the first or second aspect, the gas contains hydrogen.

[0016] In a fourth aspect of the present invention, for example, in the catalyst reuse method according to any one of the first to third aspects, the pressure of the gas in the pressurized atmosphere is 0.2 MPa or more and 20 MPa or less in gauge pressure.

[0017] In a fifth aspect of the present invention, for example, in the method for recycling a catalyst according to any one of the first to fourth aspects, in the catalyst, X and two Ys in general formula (1B) are coordinated to the metal M.

[0018] In a sixth aspect of the present invention, for example, in the method for recycling a catalyst according to any one of the first to fifth aspects, the catalyst is at least one selected from the group consisting of a metal complex represented by the following general formula (1A), a tautomer thereof, a stereoisomer thereof, and a salt thereof: (In general formula (1A), X represents an atomic group containing a typical element of Groups 13 to 15 that can be coordinated to M; each Q independently represents a bridged structure that contains a typical element of Groups 14 to 16 and connects Y and X; each Y independently represents an atomic group containing a typical element of Groups 14 to 16 that can be coordinated to M; M represents a metal atom; Z represents an anionic ligand; n represents 0 to 3; and when a plurality of Ls are present, each independently represents a neutral or anionic ligand.)

[0019] In a seventh aspect of the present invention, for example, in the catalyst recycling method according to the sixth aspect, the metal complex represented by the general formula (1A) is a metal complex represented by the following general formula (2A): (In general formula (2A), X1 represents a heteroaromatic ring formed together with two carbon atoms and a nitrogen atom, which may have a substituent, or may be bonded to another substituent to form a ring; each Q1 independently represents CH2, NH, or O, and CH2 and NH may further have a substituent; each Y1 independently represents a phosphorus atom or a nitrogen atom; each R independently represents an alkyl group, an aryl group, or an aralkyl group, which may further have a substituent; M represents a metal atom; Z represents an anionic ligand; n represents 0 to 3; and when a plurality of Ls are present, each independently represents a neutral or anionic ligand.)

[0020] In an eighth aspect of the present invention, for example, in the catalyst recycling method according to the seventh aspect, the metal complex represented by the general formula (2A) is a metal complex represented by the following general formula (3A): (In general formula (3A), R represents a hydrogen atom or an alkyl group; each A independently represents CH, CR, or N, and R represents an alkyl group, an aryl group, an aralkyl group, an amino group, a hydroxy group, or an alkoxy group; each Q independently represents CH, NH, or O, and CH and NH may further have a substituent; Y represents a phosphorus atom or a nitrogen atom; each R independently represents an alkyl group, an aryl group, or an aralkyl group, which may further have a substituent; M represents a metal atom; Z represents an anionic ligand; n represents 0 to 3; and when a plurality of Ls are present, each independently represents a neutral or anionic ligand.)

[0021] In a ninth aspect of the present invention, for example, in the method for recycling a catalyst according to any one of the first to eighth aspects, the metal M is ruthenium.

[0022] In a tenth aspect of the present invention, for example, in the method for recycling a catalyst according to any one of the first to ninth aspects, the reaction in the first reaction step is carried out in the presence of a solvent containing an organic solvent and an aqueous solvent, in a two-phase system in which the organic solvent and the aqueous solvent are separated.

[0023] In an eleventh aspect of the present invention, for example, in the catalyst reuse method according to the tenth aspect, in the first reaction step, the organic phase containing the organic solvent contains the catalyst, and the aqueous phase containing the aqueous solvent contains the first starting compound.

[0024] In a twelfth aspect of the present invention, for example, in the catalyst recycling method according to any one of the first to eleventh aspects, the reaction in the first reaction step is a hydrogenation reaction of the first starting compound with hydrogen, and a hydride of the first starting compound is obtained by the reaction.

[0025] In a thirteenth aspect of the present invention, for example, in the method for recycling a catalyst according to any one of the first to twelfth aspects, the first starting compound is at least one selected from the group consisting of carbon dioxide, hydrogen carbonate, and carbonate, and a formate is obtained from the first starting compound in the first reaction step.

[0026] A method for producing an organic compound according to a fourteenth aspect of the present invention is a method for producing an organic compound using the method for recycling a catalyst according to any one of the first to thirteenth aspects, and includes producing an organic compound from the first starting compound and producing an organic compound from the second starting compound.

[0027] A method for storing a catalyst according to a fifteenth aspect of the present invention includes storing a catalyst solution containing a catalyst under a pressurized atmosphere, wherein the catalyst is at least one selected from the group consisting of metal complexes containing a metal M and a ligand represented by the following general formula (1B) and salts thereof, and the pressurized atmosphere consists essentially of a gas other than oxygen: (In general formula (1B), X represents an atomic group containing a typical element of Groups 13 to 15 that can be coordinated to metal M; each Y independently represents an atomic group containing a typical element of Groups 14 to 16 that can be coordinated to metal M; and each Q independently represents a bridge structure that contains a typical element of Groups 14 to 16 and connects Y and X.)

[0028] The present invention will be described in detail below, but the following description is not intended to limit the present invention to a specific embodiment.

[0029] [Method for Reusing Catalyst] The method for reusing a catalyst according to the first embodiment of the present invention includes a first reaction step of reacting a first starting compound using a catalyst, a separation step of separating a catalyst solution containing the catalyst from the reaction liquid obtained in the first reaction step, a storage step of storing the separated catalyst solution under a pressurized atmosphere, and a second reaction step of reacting a second starting compound using the catalyst solution after storage.

[0030] The catalyst is at least one selected from the group consisting of metal complexes containing a metal M and a ligand represented by the following general formula (1B), and salts thereof. The pressurized atmosphere in the storage step consists essentially of gases other than oxygen. (In general formula (1B), X represents an atomic group containing a typical element of Groups 13 to 15 that can be coordinated to metal M; each Y independently represents an atomic group containing a typical element of Groups 14 to 16 that can be coordinated to metal M; and each Q independently represents a bridge structure that contains a typical element of Groups 14 to 16 and connects Y and X.)

[0031] The catalyst reuse method of the present invention includes a storage step of storing the catalyst as described above, thereby reducing catalyst deterioration. Catalyst deterioration is caused, for example, by oxidation due to oxygen contained in the system. That is, the catalyst reuse method of the present invention can suppress catalyst oxidation. Therefore, the yield can be improved when the catalyst is repeatedly used in a reaction. This allows the catalyst to be reused, thereby reducing production costs.

[0032] Each step will be described in detail below.

[0033] <First Reaction Step> In the first reaction step, a reaction of a first starting compound is typically carried out using a catalyst in the presence of a solvent containing an organic solvent and an aqueous solvent. The reaction may be carried out in a two-phase system in which the organic solvent and the aqueous solvent are separated. In this specification, in the two-phase system, the phase containing the organic solvent may be referred to as the organic phase, and the phase containing the aqueous solvent may be referred to as the aqueous phase. The organic phase and the aqueous phase may be collectively referred to as the reaction liquid.

[0034] The organic phase may contain a catalyst, and the aqueous phase may contain the starting compound. The product obtained by the catalytic reaction may be contained in the aqueous phase. This allows the catalyst to be easily separated in the separation step described below, making it easy to reuse the catalyst and repeat the reaction. Another advantage of a two-phase reaction is that it is easy to prepare an aqueous phase with a high product concentration.

[0035] The catalyst recycling method of the present invention can be widely applied to various reaction methods.

[0036] Examples of the reaction in the first reaction step include reduction reactions, dehydration condensation reactions, hydrolysis reactions, and the like. The reaction may be a reduction reaction of an inorganic compound or an organic compound. The reduction reaction is, for example, a hydrogenation reaction. The reaction in the first reaction step may be a hydrogenation reaction of a starting compound with hydrogen, i.e., a hydride of the first starting compound may be obtained in the first step. An example of the hydrogenation reaction of an inorganic compound is a reaction to produce a formate salt.

[0037] The first starting compound may be at least one selected from the group consisting of carbon dioxide, bicarbonate, and carbonate, and in the first reaction step, a formate may be obtained from the first starting compound. When the catalyst recycling method of the present invention is applied to a formate production reaction, it has the advantage of enabling efficient production of formate at low cost.

[0038] (Solvent) The solvent is preferably one that can form a two-phase system in which an organic solvent and an aqueous solvent exist in a separated state, and preferably includes a solvent that dissolves the catalyst to form a homogeneous system.

[0039] Examples of aqueous solvents include water, methanol, ethanol, ethylene glycol, glycerin, and mixtures thereof, with water being preferred from the viewpoint of low environmental impact.

[0040] Examples of the organic solvent include toluene, benzene, xylene, propylene carbonate, dioxane, dimethyl sulfoxide, tetrahydrofuran, ethyl acetate, methylcyclohexane, cyclopentyl methyl ether, and mixed solvents thereof, and from the viewpoint of separability from the aqueous solvent, the organic solvent preferably contains toluene or dioxane, and more preferably contains toluene. An example of the organic solvent is toluene.

[0041] (Catalyst) The catalyst is at least one selected from the group consisting of metal complexes containing a metal M and a ligand represented by the following general formula (1B), and salts thereof. (In general formula (1B), X represents an atomic group containing a typical element of Groups 13 to 15 that can be coordinated to metal M; each Y independently represents an atomic group containing a typical element of Groups 14 to 16 that can be coordinated to metal M; and each Q independently represents a bridge structure that contains a typical element of Groups 14 to 16 and connects Y and X.)

[0042] In general formula (1B), it is preferred that X and two Ys are coordinated to a metal M contained in the catalyst.

[0043] Examples of the typical elements of Groups 13 to 15 of the periodic table for X include a boron atom, a carbon atom, a silicon atom, a germanium atom, a tin atom, a nitrogen atom, a phosphorus atom, an arsenic atom, an oxygen atom, a sulfur atom, and a selenium atom, of which a boron atom, a carbon atom, a silicon atom, a germanium atom, a tin atom, a nitrogen atom, a phosphorus atom, an arsenic atom, and a sulfur atom are preferred, a carbon atom, a nitrogen atom, a phosphorus atom, and a sulfur atom are more preferred, and a carbon atom or a nitrogen atom is even more preferred.

[0044] X may be a zero- to monovalent atomic group. Examples of the atomic group represented by X include an alkyl group, an alkenyl group, an alkoxy group, an aromatic ring, and a heterocyclic ring, which may have a substituent or may be bonded to another substituent to form a ring.

[0045] Examples of the alkyl group for X include linear, branched, and cyclic substituted or unsubstituted alkyl groups. The alkyl group for X is preferably an alkyl group having 1 to 30 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a t-butyl group, an n-octyl group, an eicosyl group, or a 2-ethylhexyl group, and is preferably an alkyl group having 6 or less carbon atoms, and more preferably a methyl group.

[0046] The alkenyl group for X includes linear, branched, and cyclic substituted or unsubstituted alkenyl groups. The alkenyl group for X is preferably an alkenyl group having 2 to 30 carbon atoms, such as a vinyl group, an n-propenyl group, an i-propenyl group, a t-butenyl group, or an n-octenyl group, and is preferably an alkenyl group having 6 or less carbon atoms.

[0047] The alkoxy group for X includes a linear, branched, or cyclic substituted or unsubstituted alkoxy group. The alkoxy group for X is preferably a substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, such as a methoxy group, an ethoxy group, an isopropoxy group, a t-butoxy group, an n-octyloxy group, or a 2-methoxyethoxy group.

[0048] Examples of the aromatic ring in X include a phenyl ring and a naphthyl ring.

[0049] Examples of the heterocyclic ring for X include a pyrrolidine ring, a piperidine ring, a pyrroline ring, an imidazoline ring, an imidazolidine ring, a pyrrole ring, an imidazole ring, a pyridine ring, a pyrimidine ring, a triazine ring, a quinoline ring, and a quinazoline ring.

[0050] The zero- to monovalent atomic group represented by X preferably represents an atomic group containing a heteroaromatic ring formed together with two carbon atoms and a nitrogen atom, and this may have a substituent or may be bonded to another substituent to form a ring.

[0051] The zero- to monovalent atomic group represented by X is preferably a pyrroline ring, a pyridine ring, an imidazoline ring, a pyrimidine ring, or a triazine ring, more preferably a pyridine ring or a triazine ring, and even more preferably a pyridine ring.

[0052] When the zero- to monovalent atomic group represented by X has a substituent, examples of the substituent include those in Substituent Group A, and an alkyl group is preferred, and a methyl group is more preferred.

[0053] X may be an atomic group in which a hydrogen atom or an alkyl group is bonded to a nitrogen atom. The alkyl group is as described above, and is preferably a methyl group.

[0054] The bridged structure represented by Q, which connects Y and X and contains a typical element of Groups 14 to 16 of the periodic table, may have a double bond, a monocyclic structure or a fused ring structure, or may have a substituent.

[0055] Q can introduce various structures as described above. For example, the number of atoms in the portion between Y and X is preferably 1 to 5, more preferably 1 to 4, even more preferably 1 to 3, and particularly preferably 1 or 2.

[0056] The atom contained between Y and X is not particularly limited, but is preferably a carbon atom, a nitrogen atom, a phosphorus atom, an oxygen atom, or a sulfur atom, more preferably a carbon atom, a nitrogen atom, or an oxygen atom, still more preferably a carbon atom or an oxygen atom, and particularly preferably a carbon atom.

[0057] Q may have a monocyclic structure. In other words, the bridged structure represented by Q may contain a cyclic structure.

[0058] When Q has a monocyclic structure, the monocyclic structure may be directly bonded to Y and X in general formula (1B), or a divalent substituent may be sandwiched between the monocyclic structure and Y and / or Z in general formula (1B). Examples of the divalent substituent include an alkylene group having 1 to 5 carbon atoms, an alkenylene group having 2 to 5 carbon atoms, a heteroatom such as an oxygen atom or a sulfur atom, or a combination of these bonded in series.

[0059] Each Q preferably independently represents CH2, NH, or O, and CH2 and NH may further have a substituent, and more preferably represents CH2 or NH.

[0060] Q may have a fused ring structure. In other words, the bridged structure represented by Q may contain a fused ring structure.

[0061] When Q has a fused ring structure, the fused ring structure may be directly bonded to Y and X in general formula (1B), or a divalent substituent may be sandwiched between the fused ring structure and Y and / or X in general formula (1B). The divalent substituent is the same as the divalent substituent sandwiched between the monocyclic structure and Y and / or X in general formula (1A) described above.

[0062] Q may have a substituent.

[0063] The number of carbon atoms in Q is preferably 12 or less, more preferably 10 or less, and even more preferably 8 or less.

[0064] Y may be a zero- to monovalent atomic group. Each Y independently represents a zero- to monovalent atomic group containing a typical element of Groups 14 to 16 of the periodic table that can be coordinated to an atom of the metal M, and may further have a substituent. As the typical element of Groups 14 to 16 of the periodic table, a carbon atom, a nitrogen atom, a phosphorus atom, an arsenic atom, an oxygen atom, a sulfur atom, or a selenium atom is preferred, a carbon atom, a nitrogen atom, a phosphorus atom, or an arsenic atom is more preferred, a nitrogen atom or a phosphorus atom is even more preferred, and a phosphorus atom is particularly preferred.

[0065] In formula (1B), it is preferred that both Y's represent a nitrogen atom or a phosphorus atom, or that one Y represents a phosphorus atom and the other Y represents a nitrogen atom.

[0066] When the zero- to monovalent atomic group represented by Y has a substituent, examples of the substituent include those in Substituent Group A, and an alkyl group or an aryl group is preferred, and an ethyl group, a t-butyl group, or a phenyl group is more preferred.

[0067] In the catalyst, X and two Ys in general formula (1B) may be coordinated to a metal M. That is, the catalyst may be a metal complex containing a metal M and a tridentate ligand.

[0068] The catalyst is preferably a metal complex that becomes a hydride complex in the reaction system.

[0069] The catalyst is preferably at least one selected from the group consisting of a metal complex represented by the following general formula (1A), its tautomer, stereoisomer, and salt thereof.

[0070]

[0071] (In general formula (1A), X represents an atomic group containing a typical element of Groups 13 to 15 that can be coordinated to M; each Q independently represents a bridged structure that contains a typical element of Groups 14 to 16 and connects Y and X; each Y independently represents an atomic group containing a typical element of Groups 14 to 16 that can be coordinated to M; M represents the above metal atom; Z represents an anionic ligand; n represents 0 to 3; and when a plurality of Ls are present, each independently represents a neutral or anionic ligand.)

[0072] In this specification, "Group n" means "Group n of the periodic table."

[0073] X, Y, and Q in formula (1A) have the same meanings as X, Y, and Q in formula (1B), respectively, and the preferred ranges are also the same.

[0074] It should be noted that Q has a substituent, and when Q does not have either a monocyclic structure or a fused ring structure, the substituent is a substituent on the Q portion of the ring structure formed by including Q, Y, X, and M in general formula (1A).

[0075] When Q has a monocyclic structure or a fused ring structure, the substituent is a substituent of the monocyclic structure or the fused ring structure, or a substituent of Q in another ring structure formed by including Q, Y, X, and M in general formula (1A).

[0076] The substituent that Q may have may be, for example, one having a hetero atom, or another atom or atomic group.

[0077] Examples of the substituent having a hetero atom include an alkoxy group having 1 to 18 carbon atoms, an arylalkoxy group having 7 to 18 carbon atoms, an aryloxy group having 6 to 18 carbon atoms, an acyl group having 2 to 18 carbon atoms, an aroyl group having 7 to 18 carbon atoms, a dialkylamino group having 2 to 18 carbon atoms, an oxygen atom, and a sulfur atom.

[0078] Examples of the other atoms or atomic groups include aromatic groups having 3 to 18 carbon atoms, alkyl groups having 1 to 18 carbon atoms, halogen atoms, etc. Examples of the aromatic groups include aryl groups having 6 to 20 carbon atoms such as phenyl, xylyl, naphthyl, and biphenyl.

[0079] M represents a metal atom. M may contain an element from Groups 7 to 11 of the periodic table, such as manganese, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, or gold, or may contain an element from Groups 8 to 11 of the periodic table, such as iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, or gold. Among these, manganese, iron, ruthenium, cobalt, rhodium, iridium, nickel, palladium, or copper is preferred, manganese, ruthenium, rhodium, iridium, nickel, or palladium is more preferred, manganese, ruthenium, rhodium, iridium, or palladium is even more preferred, and ruthenium (Ru) is particularly preferred. M may be ruthenium (Ru) or manganese (Mn).

[0080] Examples of the anionic ligand represented by Z include a halide ion (halogen atom), a hydride ion (hydrogen atom), a nitrate ion, and a cyanide ion. Z preferably represents a halogen atom or a hydrogen atom, and more preferably represents a halogen atom. Z is further preferably a chlorine atom or a bromine atom, and particularly preferably a chlorine atom.

[0081] n represents an integer of 0 to 3, and represents the number of ligands coordinated to the metal atom represented by M. From the viewpoint of catalyst stability, n is preferably 2 or 3.

[0082] When a plurality of Ls are present, each L independently represents a neutral or anionic ligand.

[0083] Examples of the neutral ligand represented by L include ammonia, carbon monoxide, phosphines (e.g., triphenylphosphine, tris(4-methoxyphenyl)phosphine), phosphine oxides (e.g., triphenylphosphine oxide), sulfides (e.g., dimethyl sulfide), sulfoxides (e.g., dimethyl sulfoxide), ethers (e.g., diethyl ether), nitriles (e.g., p-methylbenzonitrile), heterocyclic compounds (e.g., pyridine, N,N-dimethyl-4-aminopyridine, tetrahydrothiophene, tetrahydrofuran), and the like, preferably triphenylphosphine or carbon monoxide, more preferably carbon monoxide.

[0084] Examples of the anionic ligand represented by L include a hydride ion (hydrogen atom), a nitrate ion, and a cyanide ion, and preferably a hydride ion (hydrogen atom).

[0085] In general formula (1A), it is preferred that X represents a heterocycle, Q represents CH2, NH, or O, Y represents a phosphorus atom, and M represents ruthenium.

[0086] It is also preferred that Z represents a chlorine atom, n represents 1 to 3, and each L independently represents a hydrogen atom, carbon monoxide, or triphenylphosphine.

[0087] Alternatively, in general formula (1A), it is preferable that X represents an atomic group in which a hydrogen atom or an alkyl group is bonded to a nitrogen atom, Q represents CH, NH, or O, Y represents a phosphorus atom, M represents manganese, Z represents a bromine atom, n represents 2 or 3, and each L independently represents a hydrogen atom, carbon monoxide, or triphenylphosphine.

[0088] The metal complex represented by the general formula (1A) is preferably a metal complex represented by the following general formula (2A).

[0089]

[0090] (In general formula (2A), X1 represents a heteroaromatic ring formed together with two carbon atoms and a nitrogen atom, which may have a substituent, or may be bonded to another substituent to form a ring; each Q1 independently represents CH2, NH, or O, and CH2 and NH may further have a substituent; each Y1 independently represents a phosphorus atom or a nitrogen atom; each R independently represents an alkyl group, an aryl group, or an aralkyl group, which may further have a substituent; M represents a metal atom; Z represents an anionic ligand; n represents 0 to 3; and when a plurality of Ls are present, each independently represents a neutral or anionic ligand.)

[0091] M, Q1, Z, n, and L in general formula (2A) have the same meanings as M, Q, Z, n, and L in general formula (1A), respectively, and the preferred ranges are also the same.

[0092] The heteroaromatic ring formed together with the two carbon atoms and nitrogen atom represented by X is preferably a pyrroline ring, a pyridine ring, an imidazoline ring, a pyrimidine ring, or a triazine ring, more preferably a pyridine ring or a triazine ring, and even more preferably a pyridine ring.

[0093] Examples of the substituent that X1 may have include those in Substituent Group A, and an alkyl group is preferable, and a methyl group is more preferable.

[0094] Y represents a phosphorus atom or a nitrogen atom, and is preferably a phosphorus atom. Both Ys may represent a nitrogen atom or a phosphorus atom, or one Y may represent a phosphorus atom and the other Y may represent a nitrogen atom. Both Ys may be nitrogen atoms or phosphorus atoms.

[0095] Examples of the alkyl group represented by R include linear, branched, and cyclic substituted or unsubstituted alkyl groups. The alkyl group represented by R is preferably an alkyl group having 1 to 30 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a t-butyl group, an n-octyl group, an eicosyl group, and a 2-ethylhexyl group. From the viewpoint of catalytic activity, an alkyl group having 12 or less carbon atoms is preferred, an ethyl group or a t-butyl group is preferred, and a t-butyl group is more preferred.

[0096] Examples of the aryl group represented by R include substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, such as a phenyl group, a p-tolyl group, a naphthyl group, a m-chlorophenyl group, and an o-hexadecanoylaminophenyl group. An aryl group having 12 or less carbon atoms is preferred, and a phenyl group is more preferred.

[0097] When R further has a substituent, examples of the substituent include those in Substituent Group A, and a methyl group, an ethyl group, an i-propyl group, a t-butyl group, and a phenyl group are preferred, and an ethyl group, an i-propyl group, or a t-butyl group is more preferred.

[0098] In general formula (2A), it is preferable that X1 represents a pyridine ring or a triazine ring, Q1 represents CH2, NH, or O, Y1 represents a phosphorus atom, R represents an ethyl group, a t-butyl group, or a phenyl group, and M represents ruthenium.

[0099] It is also preferred that Z represents a chlorine atom, n represents 1 to 3, and each L independently represents a hydrogen atom, carbon monoxide, or triphenylphosphine.

[0100] The metal complex represented by the general formula (2A) is preferably a metal complex represented by the following general formula (3A).

[0101]

[0102] (In general formula (3A), R represents a hydrogen atom or an alkyl group; each A independently represents CH, CR, or N, and R represents an alkyl group, an aryl group, an aralkyl group, an amino group, a hydroxy group, or an alkoxy group; each Q independently represents CH, NH, or O, and CH and NH may further have a substituent; Y represents a phosphorus atom or a nitrogen atom; each R independently represents an alkyl group, an aryl group, or an aralkyl group, which may further have a substituent; M represents a metal atom; Z represents an anionic ligand; n represents 0 to 3; and when a plurality of Ls are present, each independently represents a neutral or anionic ligand.)

[0103] Y1, R, Q1, M, Z, n, and L in general formula (3A) have the same meanings as Y1, R, Q1, M, Z, n, and L in general formula (2A), respectively, and the preferred ranges are also the same.

[0104] In general formula (3A), R0 represents a hydrogen atom or an alkyl group. Examples of the alkyl group represented by R0 include linear, branched, and cyclic substituted or unsubstituted alkyl groups. The alkyl group represented by R0 is preferably an alkyl group having 1 to 30 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a t-butyl group, an n-octyl group, an eicosyl group, and a 2-ethylhexyl group. From the viewpoint of ease of raw material procurement, an alkyl group having 6 or less carbon atoms is preferred, and a methyl group is preferred.

[0105] In formula (3A), R0 is preferably a hydrogen atom or a methyl group.

[0106] Each A independently represents CH, CR5, or N, and R5 represents an alkyl group, an aryl group, an aralkyl group, an amino group, a hydroxy group, or an alkoxy group.

[0107] Examples of the alkyl group represented by R5 include linear, branched, and cyclic substituted or unsubstituted alkyl groups. The alkyl group represented by R5 is preferably an alkyl group having 1 to 30 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a t-butyl group, an n-octyl group, an eicosyl group, and a 2-ethylhexyl group. From the viewpoint of ease of raw material procurement, an alkyl group having 12 or less carbon atoms is preferred, and a methyl group is preferred.

[0108] The aryl group represented by R5 includes a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, such as a phenyl group, a p-tolyl group, a naphthyl group, a m-chlorophenyl group, and an o-hexadecanoylaminophenyl group. An aryl group having 12 or less carbon atoms is preferred, and a phenyl group is more preferred.

[0109] The aralkyl group represented by R5 includes a substituted or unsubstituted aralkyl group having 30 or less carbon atoms, such as a trityl group, a benzyl group, a phenethyl group, a tritylmethyl group, a diphenylmethyl group, and a naphthylmethyl group, and is preferably an aralkyl group having 12 or less carbon atoms.

[0110] The alkoxy group represented by R5 is preferably a substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, such as a methoxy group, an ethoxy group, an isopropoxy group, a t-butoxy group, an n-octyloxy group, or a 2-methoxyethoxy group.

[0111] In general formula (3A), it is preferable that X1 represents a pyridine ring or a triazine ring, Q1 represents CH2, NH, or O, Y1 represents a phosphorus atom, R represents an ethyl group, a t-butyl group, or a phenyl group, and M represents ruthenium.

[0112] It is also preferred that Z represents a chlorine atom, n represents 1 to 3, and each L independently represents a hydrogen atom, carbon monoxide, or triphenylphosphine.

[0113] The metal complex represented by the general formula (3A) is preferably a ruthenium complex represented by the following general formula (4A).

[0114] The ruthenium complex represented by general formula (4A) is soluble in organic solvents and insoluble in water, making it suitable as a catalyst for the production of organic compounds. The ruthenium complex represented by general formula (4A) is suitable as a catalyst for, for example, the production of formate salts. Since the formate salt produced by the reaction is easily soluble in water, it becomes easy to separate the catalyst and the formate salt in a two-phase reaction, making it easy to separate and recover the catalyst and the formate salt from the reaction system, making it possible to produce formate salts with a high yield and facilitating the reuse of expensive catalysts.

[0115]

[0116] (In general formula (4A), R represents a hydrogen atom or an alkyl group; each Q independently represents CH, NH, or O, and CH and NH may further have a substituent; each R independently represents an alkyl group or an aryl group (provided that when Q represents NH or O, at least one R represents an aryl group); each A independently represents CH, CR, or N, and R represents an alkyl group, aryl group, aralkyl group, amino group, hydroxy group, or alkoxy group; X represents a halogen atom; n represents 0 to 3; and when a plurality of Ls are present, each L independently represents a neutral or anionic ligand.)

[0117] R0, A, Q1, Z, L, and n in general formula (4A) have the same meanings as R0, A, Q1, Z, L, and n in general formula (3A), respectively, and the preferred ranges are also the same.

[0118] The alkyl group and aryl group represented by R1 have the same meanings as the alkyl group and aryl group represented by R in general formula (3A), respectively, and the preferred ranges are also the same.

[0119] The metal complexes represented by the general formulae (1A) to (4A) may produce stereoisomers depending on the coordination mode or conformation of the ligand, and may be a mixture of these stereoisomers or a pure isomer.

[0120] The metal complexes represented by general formulas (1A) to (4A) may be produced by known methods, such as those described in E. Pidko et al., ChemCatChem 2014, 6, 1526-1530.

[0121] Specific examples of the ruthenium complex represented by general formula (4A) include the compounds shown below: In the compounds shown below, Et represents an ethyl group, tBu represents a tertiary butyl group, and Ph represents a phenyl group.

[0122]

[0123]

[0124]

[0125] The amount of catalyst (preferably ruthenium complex) used is not particularly limited. From the viewpoint of fully exhibiting the function of the catalyst, the amount of catalyst used is preferably 0.1 μmol or more per 1 L of solvent, more preferably 0.5 μmol or more, and even more preferably 1 μmol or more. Furthermore, from the viewpoint of cost, it is preferably 1 mol or less per 1 L of solvent, more preferably 10 mmol or less, and even more preferably 1 mmol or less. Furthermore, from the viewpoint of suppressing a decrease in catalytic efficiency, it may be 100 μmol or less per 1 L of solvent, or may be 10 μmol or less. When two or more catalysts are used, the total amount used may be within the above range.

[0126] (Phase Transfer Catalyst) When the first reaction step is carried out in a two-phase system, a phase transfer catalyst that facilitates the transfer of substances between the two phases may be used. Examples of the phase transfer catalyst include quaternary ammonium salts, quaternary phosphates, macrocyclic polyethers such as crown ethers, nitrogen-containing macrocyclic polyethers such as cryptands, nitrogen-containing linear polyethers, polyethylene glycols and alkyl ethers thereof, etc. Among these, quaternary ammonium salts are preferred from the viewpoint of facilitating the transfer of substances between an aqueous solvent and an organic solvent even under mild reaction conditions.

[0127] Examples of quaternary ammonium salts include methyltrioctylammonium chloride, benzyltrimethylammonium chloride, trimethylphenylammonium bromide, tributylammonium tribromide, tetrahexylammonium hydrogensulfate, decyltrimethylammonium bromide, diallyldimethylammonium chloride, dodecyltrimethylammonium bromide, dimethyldioctadecylammonium bromide, tetraethylammonium tetrafluoroborate, ethyltrimethylammonium iodide, tris(2-hydroxyethyl)methylammonium hydroxide, tetramethylammonium acetate, tetramethylammonium bromide, and tetraethylammonium iodide, with methyltrioctylammonium chloride being preferred.

[0128] The amount of the phase transfer catalyst used is not particularly limited. The amount of the phase transfer catalyst used is preferably 0.1 mmol or more, more preferably 0.5 mmol or more, and even more preferably 1 mmol or more, per 1 L of the organic and aqueous solvents. From the viewpoint of cost, the amount is preferably 1 mol or less, more preferably 500 mmol or less, and even more preferably 100 mmol or less, per 1 L of the organic and aqueous solvents. When two or more phase transfer catalysts are used, the total amount used may be within the above range.

[0129] (Other Components) In the first reaction step, an antioxidant may be added to the reaction solution as needed. Examples of antioxidants include phosphorus-based antioxidants, amine-based antioxidants, phenol-based antioxidants, and sulfur-based antioxidants, and it is preferable that the reaction solution contains at least one selected from the group consisting of phosphorus-based antioxidants, amine-based antioxidants, and phenol-based antioxidants. This configuration can particularly reduce catalyst deterioration. The organic phase may contain an antioxidant.

[0130] The phosphorus-based antioxidant is preferably one that is resistant to decomposition such as hydrolysis and has high stability, and is preferably, for example, a compound having a relatively bulky structure. The phosphorus-based antioxidant is, for example, a phosphorus compound. The phosphorus compound may be an organic phosphorus compound, or may be a phosphorous ester (phosphite), a hypophosphite, or a phosphonite. Examples of phosphites include trialkyl phosphites, triaryl phosphites, alkylaryl phosphites, and thiophosphites.

[0131] The phosphorus-based antioxidant is, for example, a compound having an aryl group. The aryl group may be, for example, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, such as a substituted or unsubstituted phenyl group, preferably a phenyl group having a t-butyl group.

[0132] Examples of phosphorus-based antioxidants include triphenyl phosphite, diisooctyl phosphite, heptakistriphosphite, triisodecyl phosphite, diphenylisooctyl phosphite, diisooctylphenyl phosphite, diphenyltridecyl phosphite, triisooctyl phosphite, trilauryl phosphite, diphenyl phosphite, tris(dipropylene glycol) phosphite, diisodecylpentaerythritol diphosphite, dioleylhydrogen phosphite, trilauryl phosphite, diisooctyl phenyl phosphite, tris(dipropylene glycol) phosphite, diisodecyl penta ...lauryl phosphite, diisooctyl phenyl phosphite, tris(dipropylene glycol) phosphite, diisodecyl pentaerythritol diphosphite, dioleylhydrogen phosphite, trilauryl phosphite, trilauryl phosphite, tris(dipropylene glycol) phosphite, diisodecyl pentaerythritol diphosphite, dioleylhydrogen phosphite, trilauryl phosphite, trilauryl phosphite, tris(dipropylene glycol) phosphite, diisodecyl pentaerythritol diphosphite, dioleylhydrogen phosphite, trilauryl phosphite, trilauryl phosphite, tris(dipropylene glycol) Nuril trithiophosphite, bis(tridecyl)phosphite, tris(isodecyl)phosphite, tris(tridecyl)phosphite, diphenyldecyl phosphite, dinonylphenylbis(nonylphenyl)phosphite, poly(dipropylene glycol)phenyl phosphite, tetraphenyldipropyl glycol diphosphite, trisnonylphenyl phosphite, tris(2,4-di-tert-butylphenyl)phosphite, tris(2,4-di-tert-butyl-5-methylphenyl) Phosphite, tris[2-tert-butyl-4-(3-tert-butyl-4-hydroxy-5-methylphenylthio)-5-methylphenyl]phosphite, tridecyl phosphite, octyl diphenyl phosphite, di(decyl)monophenyl phosphite, distearyl pentaerythritol diphosphite, a mixture of distearyl pentaerythritol and calcium stearate, alkyl (C10) bisphenol A phosphite, di(tridecyl)pentaerythritol diphosphite, di( nonylphenyl)pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2,4,6-tri-tert-butylphenyl)pentaerythritol diphosphite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, tetraphenyl-tetra(tridecyl)pentaerythritol tetraphosphite, bis(2,4-di-tert-butyl-6-methylphenyl)ethyl phosphite, tetra(tridecyl)isopropylidenediphenol diphosphite, tetra(tridecyl)-4,4'-n-butylidenebis(2-tert-butyl-5-methylphenol)diphosphite, hexa(tridecyl)-1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane triphosphite, tetrakis(2,4-di-tert-butylphenyl)biphenylene Diphosphonite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, [(1-methyl-1-propanyl-3-ylidene)tris(1,1-dimethylethyl)-5-methyl-4,1-phenylene]hexatridecyl phosphite, 2,2'-methylenebis(4,6-di-tert-butylphenyl)-2-ethylhexyl phosphite, 2,2'-methylenebis(4,6-di-tert-butylphenyl)-octadecyl phosphite, 2, 2'-Ethylidenebis(4,6-di-tert-butylphenyl)fluorophosphite, 4,4'-butylidenebis(3-methyl-6-tert-butylphenylditridecyl)phosphite, tris(2-[(2,4,8,10-tetrakis-tert-butyldibenzo[d,f][1,3,2]dioxaphosphepin-6-yl)oxy]ethyl)amine, 3,9-bis(4-nonylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5 ]undecane, 3,9-bis(2,4-di-tert-butylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 2,4,6-tri-tert-butylphenyl-2-butyl-2-ethyl-1,3-propanediol phosphite, poly 4,4'-isopropylidenediphenol C12-15 alcohol phosphite, tetraalkyl(C12-15)-4,4'-isopropylidenediphenyl diphosphite, and the like.

[0133] The phosphorus-based antioxidant is preferably tris(2,4-di-tert-butylphenyl)phosphite, triphenyl phosphite, triisodecyl phosphite, tetraalkyl(C12-15)-4,4'-isopropylidene diphenyl diphosphite, or 3,9-bis(2,4-di-tert-butylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, and particularly preferably tris(2,4-di-tert-butylphenyl)phosphite or triphenyl phosphite.

[0134] The amine-based antioxidant is an antioxidant having an amino group. Examples of the amine-based antioxidant include 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, N-phenyl-1-naphthylamine, p,p'-dioctyldiphenylamine, phenothiazine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, phenyl-α-naphthylamine, phenyl-β-naphthylamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di-β-naphthyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, and N-phenyl-N'-isopropyl-p-phenylenediamine. Nylenediamine, aldol-α-naphthylamine, phenothiazine, butyl(3,5-di-tert-butyl-4-hydroxybenzyl)malonate bis(1,2,2,6,6-pentamethyl-4-piperidyl), N1,N3-bis(2,2,6,6-tetramethylpiperidin-4-yl)isophthalamide, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, bis-(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate, and the like. The amine-based antioxidant is preferably a hindered amine-based antioxidant such as butyl(3,5-di-tert-butyl-4-hydroxybenzyl)malonate bis(1,2,2,6,6-pentamethyl-4-piperidyl), N1,N3-bis(2,2,6,6-tetramethylpiperidin-4-yl)isophthalamide, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, or bis-(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate.

[0135] The phenolic antioxidant is an antioxidant having a phenol group. Examples of the phenolic antioxidant include hindered phenolic antioxidants. Examples of the hindered phenolic antioxidant include 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butyl-4-methoxyphenol, 2-tert-butyl-4-methoxyphenol, 3-tert-butyl-4-methoxyphenol, 3,5-di-tert-butyl-4-hydroxybenzoate hexadecyl, 2,4,6-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)mesitylene, and 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione.

[0136] The phenolic antioxidant is not limited to the above-mentioned hindered phenolic antioxidant. Examples of phenolic antioxidants other than the above-mentioned hindered phenolic antioxidants include 2,6-di-tert-butyl-4-ethylphenol, 2-tert-butyl-4,6-dimethylphenol, styrenated phenol, 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 2,2'-thiobis-(6-tert-butyl-4-methylphenol), and 2,2'-thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. , 2-methyl-4,6-bis(octylsulfanylmethyl)phenol, 2,2'-isobutylidenebis(4,6-dimethylphenol), isooctyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], 2,2'-oxamido-bis[ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-ethyl hexyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate, 2,2'-ethylenebis(4,6-di-tert-butylphenol), 3,5-bis(1,1-dimethylethyl)-4-hydroxy-benzenepropanoic acid and C13-15 alkyl ester, 2,5-di-tert-amylhydroquinone, hindered phenol polymer (trade name AO.OH998 manufactured by Adeka Palmarol), 2,2'-methylenebis[6-(1-methylcyclohexyl)-p-cresol] ol], 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate, 6-[3-(3-tert-butyl-4-hydroxy-5-methyl)propoxy]-2,4,8,10-tetra-tert-butylbenz[d,f][1,3,2]-dioxaphosphepine, hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], bis[monoethyl (3,5-di-tert-butyl-4-hydroxybenzyl)phosphonate] calcium salt, reaction products of 5,7-bis(1,1-dimethylethyl)-3-hydroxy-2(3H)-benzofuranone with o-xylene, 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol, DL-α-tocopherol (vitamin E), 2,6-bis(α-methylbenzyl)-4-methylphenol , bis[3,3-bis-(4'-hydroxy-3'-tert-butyl-phenyl)butanoic acid] glycol ester, 2,6-diphenyl-4-octadecyloxyphenol, stearyl (3,5-di-tert-butyl-4-hydroxyphenyl)propionate, distearyl (3,5-di-tert-butyl-4-hydroxybenzyl)phosphonate, tridecyl-3,5-tert-butyl-4-hydroxybenzylthioacetate, thiodiethylenebis[(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] , 4,4'-thiobis(6-tert-butyl-m-cresol), 2-octylthio-4,6-di(3,5-di-tert-butyl-4-hydroxyphenoxy)-s-triazine, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), bis[3,3-bis(4-hydroxy-3-tert-butylphenyl)butylic acid]glycol ester, 4,4'-butylidenebis(2,6-di-tert-butylphenol), 4,4'-butylidenebis(6-tert-butyl-3-methylphenol), 2,2'- Ethylidenebis(4,6-di-tert-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, bis[2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl]terephthalate, 1,3,5-tris(2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl)isocyanurate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, 1,3,5-tris[(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxyethyl]isocyanurate, tetrakis[methylene-3-(3',5'-tert-tributyl-4'-hydroxyphenyl)propionate]methane, 2-tert-butyl-4-methyl-6-(2-acryloyloxy-3-tert-butyl-5-methylbenzyl)phenol, 3,9-bis[2-(3-tert-butyl-4-hydroxy-5-methylhydrocinnamoyloxy)-1,1-dimethylethyl]-2,4,8,10-tetraoxas Examples of the alkyl ester include 3-(3,5-dialkyl-4-hydroxyphenyl)propionic acid derivatives such as pyro[5.5]undecane, triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate], stearyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid amide, palmityl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid amide, myristyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid amide, and lauryl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid amide.

[0137] The sulfur-based antioxidant is an antioxidant containing a sulfur atom (S). Examples of the sulfur-based antioxidant include didodecyl 3,3′-thiodipropionate, pentaerythritol tetrakis[3-laurylthiopropionate], dimyristyl 3,3′-thiodipropionate, and distearyl 3,3′-thiodipropionate.

[0138] When an antioxidant is used, the amount used is adjusted, for example, to a range in which the antioxidant dissolves in the reaction solution. From the viewpoint of fully exerting the function of the antioxidant, the amount used of the antioxidant is preferably 1 mmol or more per 1 L of solvent. From the viewpoint of reducing the cost of the antioxidant, the amount used of the antioxidant is preferably 100 mmol or less per 1 L of solvent. One type of antioxidant may be used alone, or two or more types may be used in combination. In the present invention, an antioxidant may not be used.

[0139] The reaction solution may contain additives such as ultraviolet absorbers, light stabilizers, etc., instead of or together with the antioxidant. Examples of such additives include those disclosed in JP 2016-44190 A.

[0140] (Reaction conditions) The reaction conditions in the first reaction step are not particularly limited and can be appropriately selected depending on the type of reaction. In addition, the reaction conditions can be appropriately changed during the reaction process. The shape of the reaction vessel used for the reaction is not particularly limited.

[0141] The reaction temperature in the first reaction step is not particularly limited, but in order to allow the reaction to proceed efficiently, it is preferably 30° C. or higher, more preferably 40° C. or higher, and even more preferably 50° C. or higher. From the viewpoint of energy efficiency, it is preferably 200° C. or lower, more preferably 150° C. or lower, and even more preferably 100° C. or lower.

[0142] The reaction temperature can be adjusted by heating or cooling, and is preferably increased by heating. For example, in the reaction of hydrogen and carbon dioxide, hydrogen and carbon dioxide may be introduced into a reaction vessel and then heated to increase the temperature, or carbon dioxide may be introduced into the reaction vessel, the temperature may be increased, and then hydrogen may be introduced.

[0143] The reaction time in the first reaction step is not particularly limited, and may be, for example, 0.5 hours or more, 1 hour or more, 2 hours or more, 6 hours or more, 12 hours or more, 24 hours or more, 36 hours or more, 48 hours or more, or even 60 hours or more. The upper limit of the reaction time is not particularly limited, and may be, for example, 500 hours or less, 400 hours or less, 300 hours or less, 200 hours or less, 100 hours or less, or even 80 hours or less.

[0144] In some cases, the reaction in the first reaction step is not limited to a two-phase system, and may be a one-phase system containing only an organic solvent as the solvent.

[0145] <Separation Step> The catalyst reuse method of the present invention includes, after the first reaction step, a separation step of separating a catalyst solution containing the catalyst from the reaction liquid obtained in the first reaction step.

[0146] The catalyst solution is preferably an organic phase containing an organic solvent and a catalyst. That is, in the separation step, the reaction solution is preferably separated into an aqueous phase and an organic phase. At this time, the aqueous phase may contain the product obtained in the first reaction step. Since the aqueous phase and the organic phase can be separated by a simple method, the product can be easily recovered.

[0147] The separation step is preferably carried out under an inert atmosphere, such as a nitrogen atmosphere or an argon atmosphere.

[0148] The separation step can be carried out using a known separation method and apparatus.

[0149] <Storage Step> The catalyst reuse method of the present invention includes a storage step of storing the catalyst solution separated in the separation step under a pressurized atmosphere. The pressurized atmosphere consists essentially of a gas other than oxygen.

[0150] "The pressurized atmosphere consists essentially of gases other than oxygen" means that the oxygen concentration in the pressurized atmosphere is, for example, 5% or less on a volume basis. The oxygen concentration in the pressurized atmosphere is preferably 1% or less on a volume basis, more preferably 500 ppm or less, even more preferably 300 ppm or less, particularly preferably 100 ppm or less, and most preferably 50 ppm or less. In other words, the pressurized atmosphere is substantially free of oxygen. According to the above configuration, it is possible to reduce catalyst deterioration due to oxidation, for example. In this specification, "oxygen concentration in the pressurized atmosphere" means the oxygen concentration at 25°C and 101 kPa of the gas (atmospheric gas) that constitutes the pressurized atmosphere in which the catalyst solution is stored. The same applies to the concentrations of other gases described below.

[0151] It is preferable that the pressurized atmosphere consists essentially of gases other than oxidizing gas. That is, the oxidizing gas concentration in the pressurized atmosphere is, for example, 5% or less by volume, preferably 1% or less, more preferably 500 ppm or less, even more preferably 300 ppm or less, particularly preferably 100 ppm or less, and most preferably 50 ppm or less. That is, it is preferable that the pressurized atmosphere does not substantially contain oxidizing gas. An oxidizing gas is a gas that can be used to oxidize a substance, such as oxygen, hydrogen peroxide, water vapor, or ozone. It is also preferable that the pressurized atmosphere does not substantially contain air.

[0152] The pressurized atmosphere in the storage step preferably contains at least one selected from the group consisting of hydrogen, nitrogen, argon, and carbon dioxide, more preferably contains at least one selected from the group consisting of hydrogen, nitrogen, and argon, even more preferably contains at least one selected from the group consisting of hydrogen and nitrogen, and particularly preferably contains hydrogen. The pressurized atmosphere may consist essentially of at least one selected from the group consisting of hydrogen, nitrogen, argon, and carbon dioxide, and the total content of hydrogen, nitrogen, argon, and carbon dioxide in the pressurized atmosphere is, for example, 95.0 vol% or more, preferably 99.0 vol% or more, more preferably 99.5 vol% or more, and even more preferably 99.8 vol% or more. This configuration makes it easier to maintain the complex structure of the catalyst, thereby reducing catalyst deterioration.

[0153] The gas pressure in the pressurized atmosphere is preferably 0.1 MPa or more, more preferably 0.2 MPa or more, even more preferably 0.3 MPa or more, particularly preferably 0.6 MPa or more, in terms of gauge pressure, and is preferably 20 MPa or less, more preferably 15 MPa or less, and even more preferably 10 MPa or less. The gas pressure in the pressurized atmosphere may be 0.2 MPa or more and 20 MPa or less in terms of gauge pressure.

[0154] The storage temperature may be 15° C. or higher, or 20° C. or higher. The storage temperature may be 200° C. or lower, 150° C. or lower, or even 100° C. or lower. The storage temperature is, for example, room temperature.

[0155] The storage time is not particularly limited and may be, for example, 1 minute or more, 10 minutes or more, 30 minutes or more, 1 hour or more, 6 hours or more, or even 12 hours or more. The storage time may be 240 hours or less, 168 hours or less, 120 hours or less, or even 96 hours or less.

[0156] In another aspect, the present invention provides a method for storing a catalyst, the method comprising storing a catalyst solution containing a catalyst under a pressurized atmosphere, wherein the catalyst is at least one selected from the group consisting of metal complexes containing a metal M and a ligand represented by the above general formula (1B) and salts thereof, and the pressurized atmosphere consists essentially of a gas other than oxygen.

[0157] The ligand represented by general formula (1B) and the catalyst are as described above for the catalyst.

[0158] <Second Reaction Step> The catalyst reuse method of the present invention includes a second reaction step in which a second starting compound is reacted using the catalyst solution stored in the storage step. According to the present invention, deterioration of the catalyst used in the first reaction step is suppressed, and the catalyst can be reused in the second reaction step.

[0159] In the second reaction step, the second starting compound is typically reacted with a catalyst in the presence of a solvent containing an organic solvent and an aqueous solvent. The reaction is preferably carried out in a two-phase system in which the organic solvent and the aqueous solvent are separated.

[0160] Examples of the reaction in the second reaction step include reduction reactions, dehydration condensation reactions, hydrolysis reactions, and the like. The reaction may be a reduction reaction of an inorganic compound or an organic compound. The reduction reaction is, for example, a hydrogenation reaction. The reaction in the second reaction step may be a hydrogenation reaction of a starting compound with hydrogen, i.e., a hydride of the second starting compound may be obtained in the second step. The hydrogenation reaction of an inorganic compound is, for example, a reaction to produce a formate salt. The reaction in the second reaction step may be the same as the reaction in the first reaction step.

[0161] The second starting compound may be the compound described as the first starting compound in the first reaction step, and the preferred range is the same as that of the first starting compound. The second starting compound may have the same composition as the first starting compound. In the second reaction step, a formate may be obtained from the second starting compound.

[0162] The reaction conditions in the second reaction step are not particularly limited and can be appropriately selected depending on the type of reaction. Furthermore, the reaction conditions can be appropriately changed during the reaction process. The shape of the reaction vessel used in the reaction is not particularly limited. The preferred ranges of the reaction temperature and reaction time in the second reaction step are the same as those in the first reaction step.

[0163] <Other Steps> The catalyst recycling method of the present invention may further include steps other than the steps described above. For example, the catalyst recycling method of the present invention may further include, after the second reaction step, a second separation step of separating a catalyst solution containing the catalyst from the reaction liquid obtained in the second reaction step. The description of the <Separation Step> can be applied to the second separation step.

[0164] The catalyst recycling method of the present invention may further include a second storage step of storing the catalyst solution separated in the second separation step under a pressurized atmosphere. The pressurized atmosphere is substantially composed of a gas other than oxygen. The description of the <Storage step> can be applied to the second storage step.

[0165] The catalyst recycling method of the present invention may further include a third reaction step of reacting a third starting compound with the catalyst solution stored in the second storage step. The third starting compound may have the same composition as the first starting compound and the second starting compound.

[0166] [Method for Producing an Organic Compound] A method for producing an organic compound according to a second embodiment of the present invention uses the catalyst storage method according to the first embodiment and includes producing an organic compound from a first starting compound. The method for producing an organic compound according to the second embodiment of the present invention preferably includes producing an organic compound from a first starting compound and producing an organic compound from a second starting compound. That is, the method for producing an organic compound according to the second embodiment of the present invention includes the steps of: reacting a first starting compound using a catalyst in the presence of a solvent to produce an organic compound from the first starting compound; separating a catalyst solution containing the catalyst from the reaction solution obtained in the first reaction step; storing the catalyst solution separated in the separation step under a pressurized atmosphere; and reacting a second starting compound with the stored catalyst solution to produce an organic compound from the second starting compound. The catalyst is at least one selected from the group consisting of metal complexes containing a metal M and a ligand represented by the following general formula (1B) and salts thereof. The pressurized atmosphere in the storage step consists essentially of a gas other than oxygen. (In general formula (1B), X represents an atomic group containing a typical element of Groups 13 to 15 that can be coordinated to metal M; each Y independently represents an atomic group containing a typical element of Groups 14 to 16 that can be coordinated to metal M; and each Q independently represents a bridge structure that contains a typical element of Groups 14 to 16 and connects Y and X.)

[0167] The method for producing an organic compound of the present invention includes a storage step in which the catalyst is stored as described above, thereby reducing catalyst deterioration. Catalyst deterioration is caused, for example, by oxidation due to oxygen contained in the system. That is, the catalyst reuse method of the present invention can suppress catalyst oxidation. Therefore, the yield of the organic compound can be improved when the catalyst is repeatedly used in a reaction. This allows the catalyst to be reused, thereby reducing production costs.

[0168] Preferably, the solvent comprises an organic solvent and an aqueous solvent, and the reaction of the first starting compound and the reaction of the second starting compound are carried out in a two-phase system in which the organic solvent and the aqueous solvent are separated.

[0169] The organic phase may contain a catalyst, and the aqueous phase may contain the starting compound. Alternatively, the organic phase may contain a catalyst, and the aqueous phase may contain the produced organic compound. This allows the catalyst to be easily separated, making it easy to reuse the catalyst and repeat the reaction. Another advantage of a two-phase reaction is that it is easy to produce an aqueous phase with a high concentration of the produced organic compound.

[0170] The first starting compound and the second starting compound are, for example, the compounds described above as the first starting compound used in the catalyst reuse method according to the first embodiment. That is, the first starting compound and the second starting compound are each at least one selected from the group consisting of carbon dioxide, bicarbonate, and carbonate, and the organic compound may be a formate. Hereinafter, the first starting compound and the second starting compound may be collectively referred to as "starting compounds."

[0171] The organic compound may be a hydride of the starting compound.

[0172] The catalyst is, for example, the compound described above as the catalyst used in the catalyst reuse method according to the first embodiment. That is, the catalyst is preferably at least one selected from the group consisting of metal complexes represented by the above general formulas (1A) to (4A), their tautomers, stereoisomers, and salts thereof. The preferred ranges are also the same as those in the first embodiment. In the general formulas (1A) to (4A), it is preferable that M is ruthenium.

[0173] The amount of the catalyst (preferably a ruthenium complex) used is not particularly limited, and is, for example, as described in the first embodiment.

[0174] In the production method according to the second embodiment of the present invention, when the reaction is carried out in a two-phase system, a phase transfer catalyst may be used to facilitate the transfer of substances between the two phases. Examples of the phase transfer catalyst include those described above in the first embodiment. For example, in the reaction between hydrogen and at least one selected from the group consisting of carbon dioxide, bicarbonate, and carbonate, it is preferable to further use a quaternary ammonium salt as the phase transfer catalyst. Examples of the quaternary ammonium salt include those described above in the first embodiment, and methyltrioctylammonium chloride is preferred.

[0175] The amount of the phase transfer catalyst used is not particularly limited as long as an organic compound (for example, a formate) can be produced, and is, for example, as described in the first embodiment.

[0176] The solvent is preferably one that can form a two-phase system in which an organic solvent and an aqueous solvent exist in a separated state, and preferably includes a solvent that dissolves the catalyst to form a homogeneous system.

[0177] As the aqueous solvent, for example, the solvents described above in the first embodiment are used. From the viewpoint of low environmental impact, the aqueous solvent is preferably water.

[0178] As the organic solvent, for example, the organic solvent described above in the first embodiment can be used. From the viewpoint of separability from the aqueous solvent, it is preferable that the organic solvent contains toluene or dioxane, and more preferably toluene. The organic solvent is, for example, toluene.

[0179] The reaction conditions in the organic compound production method according to the second embodiment are not particularly limited, and the reaction conditions can be changed as appropriate during the reaction process. The shape of the reaction vessel used in the reaction is not particularly limited. The preferred ranges of the reaction temperature and reaction time in the organic compound production method according to the second embodiment are as described in the first embodiment.

[0180] The production method according to the second embodiment is suitable for reducing catalyst deterioration, which can be evaluated, for example, by the yield when the reaction of the starting compound is repeatedly carried out using the catalyst.

[0181] In the production method according to the second embodiment, it is preferable that the reaction of the starting compounds has a practically sufficient yield. For example, the yield in the first reaction is 10% or more, preferably 20% or more, and more preferably 30% or more. When the reaction of the starting compounds is repeatedly carried out using a catalyst, the yield in the second reaction is, for example, 5% or more, preferably 8% or more, more preferably 10% or more, even more preferably 15% or more, and particularly preferably 22% or more.

[0182] The method for producing an organic compound of the present invention is not limited to the above-described embodiment, and in some cases, the reaction in the method for producing an organic compound of the present invention is not limited to a two-phase system. The reaction in the method for producing an organic compound of the present invention may be a single-phase system containing only an organic solvent as a solvent.

[0183] The method for producing an organic compound of the present invention may be a batch process or a continuous process. In the continuous process, for example, the reaction of starting compounds is carried out using a continuous stirred tank reactor (CSTR) or a plug flow reactor (PFR).

[0184] Hereinafter, the reaction step of reacting starting compounds to produce an organic compound in the production method according to the second embodiment of the present invention will be described in detail for the case where the organic compound is a formate, i.e., the case where the method for producing a formate is performed.

[0185] (Method for Producing Formate) The method for producing formate includes, for example, a step of reacting hydrogen with at least one selected from the group consisting of carbon dioxide, bicarbonate, and carbonate in the presence of a solvent using the catalyst described above to produce formate in a reaction solution. In this specification, this step may be referred to as step I. In step I, the reaction between hydrogen and at least one selected from the group consisting of carbon dioxide, bicarbonate, and carbonate is preferably carried out in a two-phase system in which an organic solvent and an aqueous solvent are separated. In this reaction, the catalyst is dissolved in, for example, the organic phase. The formate produced by the reaction dissolves in the aqueous phase. This prevents the formate production reaction from terminating due to equilibrium, allowing formate to be produced in high yield. Furthermore, since the aqueous phase and the organic phase can be separated by a simple method, expensive metal catalysts tend to be reused without deactivating their catalytic activity. Reusing the catalyst can achieve high productivity.

[0186] According to Step I, hydrogen and carbon dioxide can be stored as formates (e.g., alkali metal formates). Formates have the advantages of high hydrogen storage density, safety, and chemical stability, allowing for easy handling and enabling long-term storage of hydrogen and carbon dioxide. Formates have high solubility in aqueous solvents and can be separated off as a highly concentrated aqueous solution of formate. The aqueous solution of formate can be subjected to the formic acid production process described below after adjusting the formate concentration as necessary.

[0187] Step I can be carried out, for example, as follows. First, a reaction vessel equipped with a stirrer is prepared, and a solvent is introduced into the reaction vessel. If necessary, a phase transfer catalyst may also be added. A catalyst is added to the reaction vessel and dissolved in a solvent to prepare a catalyst solution. If necessary, an antioxidant may be added to the catalyst solution in the reaction vessel. Then, hydrogen and at least one selected from the group consisting of carbon dioxide, hydrogen carbonate, and carbonate are introduced into the reaction vessel to carry out a reaction.

[0188] The reaction conditions in the method for producing a formate salt (the reaction conditions in Step I) are not particularly limited, and although the reaction conditions may be appropriately changed during the reaction process in some cases, it is preferable not to change them. The shape of the reaction vessel used in the reaction is not particularly limited.

[0189] In step I, for example, the reaction solution is stirred. The stirring conditions for the reaction solution are not particularly limited, but a stirring power of 0.2 kW / m 3 It is preferable that the power consumption is 0.5 kW / m or more. 3 More preferably, the above value is satisfied. The greater the stirring power, the more likely it is that the gas disperses better in the aqueous phase and the organic phase. When the reaction liquid is stirred, the gas (e.g., gaseous hydrogen) is drawn into the reaction liquid from above the liquid surface of the reaction liquid, thereby filling the aqueous phase and the organic phase with the gas. However, the method for filling the aqueous phase and the organic phase with the gas is not limited to the above, and a sparger may also be used.

[0190] The shape of the stirring blade used to stir the reaction solution is not particularly limited. Examples of the stirring blade include anchor blades, turbine blades, paddle blades, and also large blades such as Fullzone (registered trademark) blades (Kobe Eco-Solutions Co., Ltd.) and Maxblend (registered trademark) blades (Sumitomo Heavy Industries Process Equipment Co., Ltd.).

[0191] Methods for producing formate include the reaction between hydrogen and carbon dioxide, the reaction between hydrogen and bicarbonate, and the reaction between hydrogen and carbonate. In the reaction between hydrogen and carbon dioxide, for example, the reaction of carbon dioxide to form carbonate and the reaction of carbonate and hydrogen to produce formate proceed simultaneously.

[0192] There are no particular limitations on the method and order of introducing hydrogen and at least one selected from the group consisting of carbon dioxide, bicarbonate, and carbonate into the reaction vessel. For example, in the reaction of hydrogen with carbon dioxide, it is preferable to introduce hydrogen and carbon dioxide simultaneously. Hydrogen and carbon dioxide may be introduced individually or as a mixed gas. Furthermore, with regard to the introduction of hydrogen and carbon dioxide, one or both of them may be introduced continuously or intermittently. With regard to the reaction of hydrogen with bicarbonate and the reaction of hydrogen with carbonate, it is preferable to introduce hydrogen after introducing bicarbonate or carbonate into the reaction vessel. With regard to the introduction of hydrogen and bicarbonate or carbonate, one or both of them may be introduced continuously or intermittently.

[0193] The reaction temperature in the reaction between hydrogen and carbon dioxide, bicarbonate, or carbonate is not particularly limited, but is preferably 30°C or higher, more preferably 40°C or higher, and even more preferably 50°C or higher, in order to efficiently proceed with the reaction. From the viewpoint of energy efficiency, the reaction temperature is preferably 200°C or lower, more preferably 150°C or lower, and even more preferably 100°C or lower. The reaction temperature can be adjusted by heating or cooling, and heating is preferred. In the reaction between hydrogen and carbon dioxide, for example, hydrogen and carbon dioxide may be introduced into a reaction vessel and then the temperature may be raised by heating, or carbon dioxide may be introduced into the reaction vessel, the temperature may be raised, and then hydrogen may be introduced. In the reaction between hydrogen and bicarbonate or carbonate, for example, it is preferred to introduce (produce) bicarbonate or carbonate into a reaction vessel, then introduce hydrogen, and then raise the temperature.

[0194] The reaction pressure (gas pressure in the reaction vessel) in the reaction of hydrogen with at least one selected from the group consisting of carbon dioxide, hydrogen carbonate, and carbonate is not particularly limited, but from the viewpoint of improving the TON of the metal catalyst, it may be, for example, 0.1 MPa or more, 0.2 MPa or more, 0.5 MPa or more, 1 MPa or more, 4 MPa or more, 4.5 MPa or more, or even 5 MPa or more. The upper limit of the reaction pressure is not particularly limited, and may be, for example, 50 MPa, 20 MPa, or 10 MPa.

[0195] In order to produce formate in high yield and with excellent productivity, the concentration of the formate produced in step I (the concentration of formate in the aqueous phase) is preferably 0.5 mol / L or more, more preferably 1 mol / L or more, even more preferably 2.5 mol / L or more, and particularly preferably 5 mol / L or more. In order to simplify the production process by producing formate in a dissolved state, the concentration is preferably 30 mol / L or less, more preferably 25 mol / L or less, even more preferably 20 mol / L or less, and particularly preferably 10 mol / L or less.

[0196] The hydrogen used in the reaction can be either gaseous hydrogen from a gas cylinder or liquid hydrogen. Examples of hydrogen sources that can be used include hydrogen generated during the iron smelting process and the soda production process. Hydrogen generated during the electrolysis of water can also be used.

[0197] The carbon dioxide used in this embodiment may be pure carbon dioxide gas, or may be mixed with other components other than carbon dioxide. A mixed gas with other components may be prepared by introducing carbon dioxide gas and other gases separately, or may be prepared in advance before the introduction. Examples of components other than carbon dioxide include inert gases such as nitrogen and argon, water vapor, and any other components contained in exhaust gases. As carbon dioxide, gaseous carbon dioxide from a gas cylinder, liquid carbon dioxide, supercritical carbon dioxide, dry ice, etc. may be used.

[0198] Hydrogen gas and carbon dioxide gas may be introduced into the reaction system either singly or as a mixed gas. The ratio of hydrogen to carbon dioxide used may be equal on a molar basis, but an excess of hydrogen is preferred.

[0199] When gaseous hydrogen from a gas cylinder is used as hydrogen, the pressure may be, for example, 0.1 MPa or more, 0.2 MPa or more, 0.5 MPa or more, 1 MPa or more, 4 MPa or more, 4.5 MPa or more, or even 5 MPa or more, from the viewpoint of ensuring sufficient reactivity. Furthermore, since the equipment tends to become large, the pressure is preferably 50 MPa or less, more preferably 20 MPa or less, and even more preferably 10 MPa or less.

[0200] From the viewpoint of ensuring sufficient reactivity, the pressure of carbon dioxide is preferably 0.1 MPa or more, more preferably 0.2 MPa or more, and even more preferably 0.5 MPa or more. In addition, since the equipment tends to become large, the pressure is preferably 50 MPa or less, more preferably 20 MPa or less, and even more preferably 10 MPa or less.

[0201] The hydrogen gas and carbon dioxide gas may be bubbled (injected) into the catalyst solution. Alternatively, after introducing a gas containing hydrogen gas and carbon dioxide, the catalyst solution and the hydrogen gas and carbon dioxide gas may be stirred by stirring with a stirring device, rotating the reaction vessel, or the like.

[0202] The method for introducing carbon dioxide, hydrogen, a metal catalyst, a solvent, and the like used in the reaction into a reaction vessel is not particularly limited, and all of the raw materials may be introduced at once, some or all of the raw materials may be introduced stepwise, some or all of the raw materials may be introduced continuously, or a combination of these methods may be used.

[0203] Examples of bicarbonates and carbonates used in the reaction include carbonates or bicarbonates of alkali metals or alkaline earth metals. Examples of bicarbonates include sodium bicarbonate and potassium bicarbonate, with potassium bicarbonate being preferred from the viewpoint of high solubility in water. That is, in this embodiment, it is preferable that the starting compound contains potassium bicarbonate as the bicarbonate. Examples of carbonates include sodium carbonate, potassium carbonate, potassium sodium carbonate, and sodium sesquicarbonate.

[0204] Bicarbonates and carbonates can be produced by the reaction of carbon dioxide with a base. For example, bicarbonates or carbonates may be produced by introducing carbon dioxide into a basic solution.

[0205] The solvent for the basic solution used in producing the bicarbonate or carbonate is not particularly limited, and examples thereof include water, methanol, ethanol, N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, benzene, toluene, and mixed solvents thereof. It is preferable for the solvent to contain water, and water is more preferable. The base used in the basic solution is not particularly limited as long as it can react with carbon dioxide to produce the bicarbonate or carbonate, and a hydroxide is preferable. Examples include lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, cesium bicarbonate, potassium hydroxide, sodium hydroxide, diazabicycloundecene, and triethylamine. Of the above, a hydroxide is preferable, with potassium hydroxide and sodium hydroxide being more preferable, and potassium hydroxide being even more preferable.

[0206] The content of the base in the basic solution is not particularly limited as long as it allows the production of bicarbonate and carbonate. From the viewpoint of ensuring the production amount of formate, the content of the base is preferably 0.1 mol or more, more preferably 0.5 mol or more, and even more preferably 1 mol or more, per 1 L of aqueous solvent. From the viewpoint of reaction efficiency, the content of the base is preferably 30 mol or less, more preferably 20 mol or less, and even more preferably 15 mol or less. However, if the solubility of the base in the aqueous phase is exceeded, the solution will become suspended.

[0207] The ratio of the amounts of carbon dioxide to base used in the reaction of carbon dioxide and base is preferably 0.1 or more, more preferably 0.5 or more, and even more preferably 1.0 or more, in terms of producing carbonate from carbon dioxide. Furthermore, from the viewpoint of carbon dioxide utilization efficiency, it is preferably 8.0 or less, more preferably 5.0 or less, and even more preferably 3.0 or less. The ratio of the amounts of carbon dioxide to base used may be the ratio of the molar amounts of carbon dioxide to base introduced into the reaction vessel, and is expressed as the molar amount (mol) of CO2 / the molar amount (mol) of base. By setting the ratio of the amounts of carbon dioxide to base used within the above range, excessive introduction of carbon dioxide into the reaction vessel can be suppressed, unreacted carbon dioxide can be minimized, and the final conversion efficiency of formic acid can be easily improved. Furthermore, carbon dioxide can be hydrogenated from the reaction of carbon dioxide and base to produce bicarbonate or carbonate in the same vessel, thereby producing formate. The unreacted carbon dioxide can be recovered from the reaction vessel and reused.

[0208] Although there are no particular limitations on the method and order of introducing carbon dioxide and a base into a reaction vessel, it is preferable to introduce carbon dioxide into the reaction vessel after introducing the base. Furthermore, the introduction of carbon dioxide and the base may be carried out continuously or intermittently, with respect to either or both of them.

[0209] The reaction temperature in the reaction of carbon dioxide with a base to produce a bicarbonate or a carbonate is not particularly limited, but in order to dissolve carbon dioxide in the aqueous phase, the reaction temperature is preferably 0° C. or higher, more preferably 10° C. or higher, and even more preferably 20° C. or higher. The reaction temperature is also preferably 100° C. or lower, more preferably 80° C. or lower, and even more preferably 40° C. or lower.

[0210] The reaction time for producing a bicarbonate or carbonate by the reaction of carbon dioxide with a base is not particularly limited, but is, for example, preferably 0.5 hours or more, more preferably 1 hour or more, and even more preferably 2 hours or more from the viewpoint of ensuring a sufficient amount of produced bicarbonate or carbonate, and is preferably 24 hours or less, more preferably 12 hours or less, and even more preferably 6 hours or less from the viewpoint of cost.

[0211] The bicarbonate or carbonate produced by the reaction of carbon dioxide with a base can be used in the reaction of hydrogen with the bicarbonate or carbonate in the organic compound production method according to the second embodiment of the present invention. Alternatively, the bicarbonate or carbonate may be produced by reacting carbon dioxide with a base in a reaction vessel, and then introduced into the reaction vessel.

[0212] [Method for Producing Formic Acid] The method for producing formic acid of this embodiment includes a step of producing a formate by the method for producing a formate described above, and a step of protonating at least a portion of the formate to generate formic acid. In this specification, the step of protonating at least a portion of the formate to generate formic acid may be referred to as step II. The method for producing formic acid of this embodiment includes, for example, step I and step II of the method for producing a formate described above.

[0213] In the above-mentioned step I, the produced formate salt is eluted into the aqueous phase, and an aqueous solution of the formate salt can be obtained by separating the aqueous phase. It is preferable that the aqueous phase in step I is separated and the obtained aqueous solution is treated, for example, with an electrodialysis device in step II to produce formic acid. The aqueous phase to be separated is the aqueous phase after completion of step I.

[0214] In step II, the aqueous solution of formate obtained in step I may be used as is, or, if necessary, may be used after adjusting the formate concentration in the aqueous solution by concentration or dilution. Examples of methods for diluting the aqueous solution of formate include a method of adding pure water for dilution. Examples of methods for concentrating the aqueous solution of formate include a method of distilling water from the aqueous solution and a method of concentrating the aqueous solution using a separation membrane unit equipped with a reverse osmosis membrane. When performing treatment using an electrodialysis device, a high-concentration aqueous solution of formate may suffer from a loss of formate due to concentration diffusion. To prevent this, it is preferable to separate the aqueous phase in step I, adjust the formate concentration by dilution, and then use the resulting aqueous solution in step II. By preparing a high-concentration aqueous solution of formate in step I and adjusting the concentration of this aqueous solution by dilution before using it in step II, formic acid can be produced in a higher yield and with better productivity.

[0215] The degree of concentration adjustment (preferably dilution) of the aqueous solution of formate obtained in step I is not particularly limited. The concentration of formate in the aqueous solution after the concentration adjustment is preferably a concentration suitable for electrodialysis, preferably 2.5 mol / L or more, more preferably 3 mol / L or more, more preferably 4.75 mol / L or more, and even more preferably 5 mol / L or more. Furthermore, when performing treatment using an electrodialysis apparatus, from the viewpoint of suppressing loss of formate due to concentration diffusion, the concentration of formate is preferably 20 mol / L or less, more preferably 15 mol / L or less, and even more preferably 10 mol / L or less.

[0216] Pure water can be used for dilution. Alternatively, the water produced in step II may be used for dilution. Reusing the water produced in step II for dilution is preferred because it has advantages such as reducing wastewater treatment costs and environmental loads.

[0217] In the method for producing formic acid according to this embodiment, an acid may be added to the aqueous solution of the formate obtained in step I, followed by decarbonation, and then the aqueous solution may be used in step II. That is, the aqueous phase in step I may be separated, an acid may be added, and the solution may be decarbonated before being used in step II. The aqueous solution of the formate obtained in step I may contain unreacted carbonate or bicarbonate produced by a side reaction. Electrodialysis of a solution containing carbonate or bicarbonate may result in the generation of carbon dioxide, which may reduce the dialysis efficiency. Therefore, by adding an acid to the aqueous solution of the formate obtained in step I, followed by decarbonation, and then electrodialysis, formic acid can be produced in a higher yield and with better productivity.

[0218] Examples of acids used in the decarboxylation treatment include formic acid, citric acid, acetic acid, malic acid, lactic acid, succinic acid, tartaric acid, butyric acid, fumaric acid, propionic acid, hydrochloric acid, nitric acid, and sulfuric acid, and it is preferable to use formic acid.

[0219] From the viewpoint of suppressing the amount of carbon dioxide generated during electrodialysis, the amount of acid used relative to the amount of carbon dioxide present in the solution is preferably 50% or more, more preferably 80% or more. Furthermore, by maintaining the pH of the formate solution near neutral during electrodialysis, deterioration of the electrodialysis apparatus can be suppressed, so the amount of acid used relative to the amount of carbon dioxide present in the solution is preferably 150% or less, more preferably 120% or less.

[0220] In the present embodiment, the proportion of the formate salt protonated in step II is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more, relative to the initial molar amount of formate salt in the aqueous solution of formate salt, from the viewpoint of increasing the purity of the recovered aqueous solution of formic acid.

[0221] Examples of the electrodialysis apparatus used in step II include a two-compartment electrodialysis apparatus using a bipolar membrane and an anion exchange membrane or a cation exchange membrane, and a three-compartment electrodialysis apparatus using a bipolar membrane, an anion exchange membrane, and a cation exchange membrane.

[0222] FIG. 1 is a schematic diagram showing an example of a three-compartment electrodialysis apparatus. The electrodialysis apparatus shown in FIG. 1 includes a plurality of bipolar membranes, anion exchange membranes, and cation exchange membranes. These bipolar membranes, anion exchange membranes, and cation exchange membranes are arranged between an anode and a cathode to form a base tank, a sample tank (salt tank), and an acid tank. By circulating an aqueous solution of formate salt to the sample tank while energizing the electrodialysis apparatus, the formate salt is converted to formic acid, and formic acid can be recovered from the acid tank, water from the sample tank, and hydroxide from the base tank.

[0223] The two-compartment electrodialysis device includes, for example, a plurality of bipolar membranes and cation exchange membranes. These bipolar membranes and cation exchange membranes are alternately arranged between an anode and a cathode, so that a salt chamber is formed between each bipolar membrane and the cation exchange membrane located on the cathode side thereof, and a base chamber is formed between each bipolar membrane and the cation exchange membrane located on the anode side thereof. By circulating an aqueous solution of formate salt through the salt chamber while energizing the electrodialysis device, hydroxide is produced in the base chamber, and the formate salt circulating through the salt chamber is converted to formic acid.

[0224] In step II, the formate salt can be protonated in a simple manner using an electrodialysis device to obtain a solution of formic acid.

[0225] 2, a formic acid production system 100 of this embodiment includes, for example, a formate production apparatus 10 and an electrodialysis apparatus 30. The production system 100 may further include a dilution apparatus 20 and a dilution water storage unit 40, a carbon dioxide cylinder 60 for introducing carbon dioxide into the production apparatus 10, and a hydrogen cylinder 50 for introducing hydrogen into the production apparatus 10. The concentrations and pressures of carbon dioxide and hydrogen can be adjusted by valves 1 and 2 provided in pipes L1 and L2.

[0226] The formate produced in the production apparatus 10 is separated into an aqueous phase, and then supplied as an aqueous solution of formate to the electrodialysis apparatus 30. At this time, as shown in Fig. 2 , the aqueous solution of formate may be previously sent to the dilution apparatus 20 via a flow path L3, and the concentration of formate in the aqueous solution may be adjusted by dilution in the dilution apparatus 20.

[0227] The aqueous solution in which the formate concentration has been adjusted by the dilution device 20 is sent to the electrodialysis device 30 via the flow path L4, where at least a portion of the formate is protonated. As a result, formic acid and water are produced from the formate. The produced formic acid can be extracted via the flow path L5. The produced water may also be sent to the storage unit 40 via the flow path L7.

[0228] A portion of the formic acid produced by the electrodialysis device 30 may be delivered to the storage unit 40 through flow path L6. The storage unit 40 may further include a water supply unit 70 and a formic acid supply unit 80. The aqueous solution of formic acid prepared in the storage unit 40 may be supplied to the dilution device 20 through flow path L9, thereby subjecting the aqueous solution of formate to decarbonation treatment. Each flow path of the production system 100 may include a valve (e.g., valves 3 and 5 in FIG. 2 ) for adjusting the pressure or supply amount.

[0229] According to the production system 100 of this embodiment, formic acid can be produced with high yield and excellent productivity.

[0230] The formate salts and formic acid thus obtained have a wide range of applications in various fields, such as use as a silage additive, a feed preservative, a leather tanning agent, a textile dyeing agent, a rubber coagulant, an antifreeze agent, a cleaning agent for precision machinery, a neutralizing agent, a precipitant for heavy metals, a deicing agent, a cutting fluid, a heat transfer fluid, a lubricant, a hydride ion source, and a hydrogen supply source.

[0231] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto. In the examples, a formate salt was synthesized by hydrogenating a starting compound with hydrogen using a catalyst, and then the catalyst solution was separated and stored. The stored catalyst solution was used to synthesize a formate salt by hydrogenating the starting compound again, thereby evaluating the effect of reducing catalyst degradation.

[0232] <Catalyst Synthesis> (Catalyst 1) Catalyst 1 was synthesized by the following procedure. Under an inert atmosphere, 40 mg (0.1 mmol) of Ligand A (see below) was added to a suspension of 95.3 mg (0.1 mmol) of [RuHCl(PPh)(CO)] in 5 mL of tetrahydrofuran (THF). The mixture was stirred and heated at 65°C for 3 hours to carry out the reaction. The mixture was then cooled to room temperature (25°C). The resulting yellow solution was filtered, and the filtrate was evaporated to dryness under vacuum. The resulting yellow residual oil was dissolved in a small amount of THF (1 mL), and hexane (10 mL) was slowly added to precipitate a yellow solid, which was then filtered. The filtrate was dried under vacuum to obtain the following yellow crystals (55 mg, 97% yield). In the catalyst 1 and ligand A shown below, tBu represents a tertiary butyl group.

[0233]

[0234] 31 P{ 1 H}(C6D6):90.8(s), 1 H (C6D6): -14.54 (t, 1H, J = 20.0Hz), 1.11 (t, 18H, J = 8.0Hz), 1.51 (t, 18H, J = 8.0Hz), 2.88 (dt, 2H, J = 16.0Hz, J=4.0Hz), 3.76 (dt, 2H, J=16.0Hz, J=4.0Hz), 6.45 (d, 2H, J=8.0Hz), 6.79 (t, 1H, J=8.0Hz). 13 C{ 1 H}NMR (C6D6): 29.8 (s), 30.7 (s), 35.2 (t, J = 9.5 Hz), 37.7 (t, J = 6.0 Hz), 37.9 (t, J=6.5Hz), 119.5 (t, J=4.5Hz), 136.4 (s), 163.4 (t, J=5.0Hz), 209.8 (s).

[0235] <Production of formate salt by batch method> [Calculation of yield] In the following Examples 1 to 3 and Comparative Examples 1 and 2, the yield of formate salt (potassium formate) was calculated by the following method.

[0236] ​First, the amount of formate contained in the aqueous phase was quantified as follows. 500 μL of the aqueous phase obtained after the reaction was taken out, and 100 μL of dimethyl sulfoxide was added as a reference substance, and the mixture was dissolved in 500 μL of heavy water. In this way, a measurement sample was prepared. 1 H NMR measurement was performed. From the obtained NMR spectrum, the integral value Ia of the peak derived from potassium formate and the integral value Ib of the peak derived from dimethyl sulfoxide were identified. The amount of potassium formate, X (mol), was calculated using the following formula (1): X = (W / M) × {Ia / (Ib / R)} × (A / B) (1) (In formula (1), W is the weight (g) of dimethyl sulfoxide used in the quantification of potassium formate, M is the molecular weight of dimethyl sulfoxide, R is the ratio of the number of protons in dimethyl sulfoxide per molecule to the number of protons in potassium formate per molecule, Ia is the integral value of the NMR peak derived from potassium formate, Ib is the integral value of the NMR peak derived from dimethyl sulfoxide, A is the mass (g) of the aqueous phase obtained after the reaction, and B is the mass (g) of the aqueous solution used in the quantification of potassium formate.)

[0237] Then, based on the amount of substance X (mol) of the produced formate and the total amount of substance Z (mol) of carbon dioxide, hydrogen carbonate, and carbonate used in the reaction (the amount of substance Z is potassium hydrogen carbonate in the following Examples 1 to 3 and Comparative Examples 1 and 2), the yield (%) of the formate was calculated according to the following formula (2): Yield of formate=100×X / Z (2)

[0238] Example 1 Under a nitrogen gas atmosphere, 3 mL of water, potassium bicarbonate, 3 mL of toluene, catalyst 1, and methyltrioctylammonium chloride as a phase transfer catalyst were charged into a reactor. In the aqueous phase, the concentration of potassium bicarbonate was 2 mol / L. In the organic phase, the concentration of catalyst 1 was 0.12 mmol / L, and the concentration of the phase transfer catalyst was 54 mmol / L. For the first reaction, hydrogen gas was charged up to 0.6 MPa, then the temperature was raised to 90°C and the mixture was stirred at 800 rpm for 3 hours. After stirring, the mixture was cooled to room temperature, and the pressure was carefully released after cooling.

[0239] Next, the reactor was purged with nitrogen gas. Under a nitrogen gas atmosphere, the reaction solution was removed from the reactor and separated into an organic phase and an aqueous phase. Using this aqueous phase, the yield of formate in the first reaction was calculated by the method described above.

[0240] The separated organic phase was placed in an empty reactor and stored by leaving it to stand at room temperature (25° C.) under a hydrogen gas gauge pressure of 0.3 MPa for 64 hours.

[0241] Under a nitrogen gas atmosphere, 3 mL of water and potassium bicarbonate were added to the reactor containing the organic phase after standing. At this time, the potassium bicarbonate concentration in the aqueous phase was adjusted to 2 mol / L. Then, for the second reaction, hydrogen gas was added up to 0.6 MPa, the temperature was raised to 90°C, and stirring was performed at 800 rpm for 3 hours. After stirring, the mixture was cooled to room temperature, and the pressure was carefully released after cooling.

[0242] The reactor was purged with nitrogen gas. Under a nitrogen gas atmosphere, the reaction solution was removed from the reactor and separated into an organic phase and an aqueous phase. The yield of formate in the second reaction was calculated using the method described above, similar to that of the first reaction.

[0243] Example 2 The same procedure as in Example 1 was carried out, except that the storage conditions for the organic phase separated after the first reaction were changed to a nitrogen gas gauge pressure of 0.6 MPa.

[0244] Example 3 The same procedure as in Example 1 was carried out, except that the storage conditions for the organic phase separated after the first reaction were changed to a hydrogen gas gauge pressure of 0.6 MPa.

[0245] Comparative Example 1 The same procedure as in Example 1 was carried out, except that the storage conditions for the organic phase separated after the first reaction were changed to a nitrogen gas atmosphere. That is, in Comparative Example 1, the inside of the reactor was not pressurized during storage of the organic phase.

[0246] Comparative Example 2 Comparative Example 2 was carried out in the same manner as in Comparative Example 1, except that the storage conditions for the organic phase separated after the first reaction were changed to a hydrogen gas atmosphere.

[0247] Table 1 shows the reaction yields in Examples 1 to 3 and Comparative Examples 1 and 2. The storage pressure in Table 1 is a gauge pressure.

[0248]

[0249] As can be seen from Table 1, Examples 1 to 3, in which the second reaction was carried out using an organic phase stored under a pressurized atmosphere, had higher yields in the second reaction than Comparative Examples 1 and 2, in which the second reaction was carried out using an organic phase stored under normal atmospheric pressure. Therefore, catalyst deterioration was reduced in Examples 1 to 3. Furthermore, the yields in Examples 1 to 3 were sufficient for practical use.

[0250] <Production of formate salts by continuous method (CSTR)> In the continuous reactions of Reference Examples 1 to 8 and Examples 4 to 10 below, the amount of formate salt contained in the aqueous phase was quantified as follows. 2.0 mL of the aqueous phase obtained after the reaction was taken out, and 60 mg of dimethyl sulfoxide was added as a reference substance. The mixture was dissolved in 2.0 mL of heavy water to prepare a measurement sample. 1 H NMR measurement was performed. From the obtained NMR spectrum, the integral value Ia of the peak derived from potassium formate and the integral value Ib of the peak derived from dimethyl sulfoxide were identified. Based on the above measurement results and the total molar concentration Y (mol / L) of carbon dioxide, bicarbonate, and carbonate used in the reaction (molar concentration of potassium bicarbonate in the following Examples and Reference Examples), the yield (%) of the formate was calculated according to the following formula (3): Formate yield=100×(W / M)×{Ia / (Ib / R)} / (Y×A) (3) (In formula (3), W is the weight (g) of dimethyl sulfoxide used in the quantitative determination of potassium formate, M is the molecular weight of dimethyl sulfoxide, R is the ratio of the number of protons of dimethyl sulfoxide per molecule to the number of protons of potassium formate per molecule, Ia is the integral value of the NMR peak derived from potassium formate, Ib is the integral value of the NMR peak derived from dimethyl sulfoxide, Y is the sum of the molar concentrations of carbon dioxide, bicarbonate, and carbonate used in the reaction (the molar concentration of potassium bicarbonate in the following Examples and Reference Examples), and A is the volume (L) of the aqueous phase obtained after the reaction and used in the measurement sample.)

[0251] [Study on the amount of solution in the reactor in the first reaction step] (Reference Example 1) Figure 3 is a schematic diagram showing the configuration of the apparatus used in Reference Examples 1 to 4. Under a nitrogen gas atmosphere, 80 mL of a 2 mol / L potassium bicarbonate aqueous solution was prepared as the aqueous phase. Under a nitrogen gas atmosphere, 20 mL of a toluene solution containing catalyst 1 (250 μmol / L) and methyltrioctylammonium chloride (54 mmol / L) as a phase transfer catalyst was prepared as the organic phase. 32 mL of the potassium bicarbonate aqueous solution (aqueous phase) and 8 mL of the toluene solution (organic phase) were charged into the reactor. The remaining aqueous phase was transferred to one of two containers connected to the reactor by piping, and the remaining organic phase was transferred to the other. Pumps were prepared to transport these liquids to the reactor at a constant rate. Another pump was also prepared to withdraw the reaction liquid from the reactor to a collection container 300 at a constant rate. Stirring of the solution in the reactor was started at 800 rpm, hydrogen gas was introduced into the reactor up to 5 MPa, and the temperature was raised to 90°C. Next, the aqueous phase and organic phase were transferred from each of the above containers to the reactor so that the residence time was 60 minutes, while the reaction solution was extracted from the reactor, and the reactor was brought to a steady state. When the prepared aqueous phase and organic phase were gone, the transfer was stopped, the reactor was cooled to room temperature, and then the pressure was carefully released.

[0252] Next, the inside of the reactor was purged with nitrogen gas. Under a nitrogen gas atmosphere, the reaction solution was removed from the recovery vessel 300 and separated into an aqueous phase 220 and an organic phase 210. Using this aqueous phase 220, the yield of the formate was calculated from formula (3) by the method described above.

[0253] (Reference Examples 2 and 3) Under a nitrogen gas atmosphere, 60 mL of a 2 mol / L aqueous potassium bicarbonate solution was prepared as the aqueous phase. Under a nitrogen gas atmosphere, 60 mL of a toluene solution containing catalyst 1 (60 μmol / L) and methyltrioctylammonium chloride (54 mmol / L) as a phase transfer catalyst was prepared as the organic phase. Thereafter, the reaction was carried out in the same manner as in Reference Example 1, except that the amounts of the organic phase and aqueous phase charged into the reactor were changed as shown in Table 2.

[0254] (Reference Example 4) A reaction was carried out in the same manner as in Reference Example 2, except that hydrogen gas was introduced into the reactor up to 5 MPa, the temperature was raised to 90°C, and the solution in the reactor was maintained at 90°C for 40 minutes while stirring at 800 rpm, and then the liquid was started to be pumped.

[0255] Table 2 shows the volumes of the aqueous potassium hydrogen carbonate solution (aqueous phase) and the toluene solution (organic phase) charged into the reactor, and the yields of formate salts in Reference Examples 1 to 4.

[0256]

[0257] As can be seen from a comparison between Reference Example 1 and Reference Example 2, when the volume of the potassium bicarbonate aqueous solution and the volume of the toluene solution were the same, a higher yield of formate was obtained. Furthermore, as can be seen from a comparison between Reference Example 2 and Reference Example 3, the yield of formate did not change significantly even when the total volume of the solution in the reactor was increased. Furthermore, as can be seen from a comparison between Reference Example 2 and Reference Example 4, the yield of formate was further improved by maintaining the solution in the reactor at 90°C for 40 minutes before pumping.

[0258] Example 4 Figure 4 is a schematic diagram showing the configuration of the apparatus used in Examples 4 to 6. Under a nitrogen gas atmosphere, 60 mL of a 2 mol / L potassium bicarbonate aqueous solution was prepared as the aqueous phase. Under a nitrogen gas atmosphere, 60 mL of a toluene solution containing catalyst 1 (60 μmol / L) and methyltrioctylammonium chloride (54 mmol / L) as a phase transfer catalyst was prepared as the organic phase. 20 mL of the potassium bicarbonate aqueous solution (aqueous phase) and 20 mL of the toluene solution (organic phase) were charged into the reactor. Two containers connected to the reactor by piping were used: one was transferred to the remaining aqueous phase, and the other was transferred to the remaining organic phase. Pumps were prepared to transport these liquids to the reactor at a constant rate. Another pump was also prepared to withdraw the reaction liquid from the reactor to a collection container 300 at a constant rate. Thereafter, as the first reaction, stirring of the solution in the reactor was started at 800 rpm, hydrogen gas was introduced into the reactor up to 5 MPa, and the temperature was raised to 90°C and maintained at that temperature for 40 minutes. Thereafter, the aqueous phase and organic phase were transferred from each of the above containers to the reactor while the reaction solution was extracted so that the residence time of the solution in the reactor was 40 minutes, and the reactor was brought to a steady state. Transfer of the solution was stopped when the prepared aqueous phase and organic phase were gone, and the reactor was cooled to room temperature, after which the pressure was carefully released.

[0259] The reactor was purged with nitrogen gas. Under a nitrogen gas atmosphere, the reaction solution was removed from the recovery container 300, and the aqueous phase 220 and the organic phase 210 were separated. Using this aqueous phase 220, the yield of the formate salt was calculated from formula (3) by the method described above. The organic phase 210 was placed in an empty pressure-resistant container (not shown), and the container was filled up to 60 mL with toluene. The container was then left to stand at room temperature for 20 hours under a hydrogen gas gauge pressure of 0.6 MPa and stored.

[0260] Under a nitrogen gas atmosphere, 60 mL of a 2 mol / L aqueous potassium bicarbonate solution was prepared as a new aqueous phase. 20 mL of the stored organic phase 210 and 20 mL of the above aqueous phase were added to the reactor. The remaining aqueous phase was transferred to one of two containers connected to the reactor by piping, and the remaining organic phase was transferred to the other. A pump was prepared to transport these to the reactor at a constant rate. Another pump was also prepared to extract the reaction solution from the reactor to the recovery container 300 at a constant rate. Then, for the second reaction, stirring of the solution in the reactor was started at 800 rpm, hydrogen gas was introduced to the reactor up to 5 MPa, and the temperature was raised to 90°C and maintained for 40 minutes. The aqueous and organic phases were then pumped from each container to the reactor so that the residence time was 40 minutes, while the reaction solution was withdrawn from the reactor, and the reactor was brought to a steady state. When the prepared aqueous and organic phases were depleted, the liquid transfer was terminated, the reactor was cooled to room temperature, and the pressure was carefully released.

[0261] The atmosphere inside the reactor was replaced with nitrogen gas. Under a nitrogen gas atmosphere, the reaction solution was removed from the recovery vessel 300 and separated into an aqueous phase 220 and an organic phase 210. As in the first reaction, the yield of formate in the second reaction was calculated by the method described above.

[0262] Example 5 The same procedure as in Example 4 was carried out, except that 6 mM of Irgafos 168 (manufactured by BASF) was further added to the organic phase as an antioxidant and the reaction was carried out. When the ruthenium concentration in the organic phase after the first reaction was measured by ICP-MS, it was found that 3% of ruthenium per unit volume had disappeared. This is thought to be due to the elution of the ruthenium catalyst into the aqueous phase.

[0263] Example 6 The same procedure as in Example 4 was carried out, except that the storage conditions for the organic phase 210 separated after the first reaction were changed to a nitrogen gas gauge pressure of 0.6 MPa.

[0264] Table 3 shows the reaction yields in Examples 4 to 6. The storage pressures in Table 3 are gauge pressures.

[0265]

[0266] As can be seen from Table 3, the yields of Examples 4 to 6, in which the second reaction was carried out using an organic phase stored under a pressurized atmosphere, were practically sufficient. Furthermore, as can be seen from a comparison between Examples 4 and 6, the second yield was further improved by using hydrogen as the gas in the pressurized atmosphere. As can be seen from a comparison between Examples 4 and 5, the yield of formic acid was further improved by adding an antioxidant to the organic phase.

[0267] [Study on Residence Time in the First Reaction Step] (Reference Example 5) In Reference Example 5, the same apparatus (Figure 3) as in Reference Examples 1 to 4 was used. Under a nitrogen gas atmosphere, 60 mL of a 2 mol / L potassium bicarbonate aqueous solution was prepared as the aqueous phase. Under a nitrogen gas atmosphere, 60 mL of a toluene solution containing catalyst 1 (60 μmol / L) and methyltrioctylammonium chloride (54 mmol / L) as a phase transfer catalyst was prepared as the organic phase. 20 mL of the potassium bicarbonate aqueous solution (aqueous phase) and 20 mL of the toluene solution (organic phase) were charged into the reactor. The remaining aqueous phase was transferred to one of two containers connected to the reactor by piping, and the remaining organic phase was transferred to the other. Pumps were prepared to transport these liquids to the reactor at a constant rate. In addition, another pump was prepared to withdraw the reaction liquid from the reactor to a collection container 300 at a constant rate. Stirring of the solution in the reactor was started at 800 rpm, hydrogen gas was introduced into the reactor up to 5 MPa, and the temperature was raised to 90°C and maintained at this temperature for 40 minutes. Thereafter, the aqueous phase and organic phase were transferred from each of the above containers to the reactor while the reaction solution was extracted so that the residence time of the solution in the reactor was 40 minutes, and the reactor was brought to a steady state. Transfer of the solution was stopped when the prepared aqueous phase and organic phase were gone, and the reactor was cooled to room temperature, after which the pressure was carefully released.

[0268] Next, the inside of the reactor was purged with nitrogen gas. Under a nitrogen gas atmosphere, the reaction solution was removed from the recovery vessel 300 and separated into an aqueous phase 220 and an organic phase 210. Using this aqueous phase 220, the yield of the formate was calculated from formula (3) by the method described above.

[0269] (Reference Examples 6 and 7) Reactions were carried out in the same manner as in Reference Example 5, except that the heating time of the reactor before the start of liquid supply and the residence time of the solution in the reactor after the start of liquid supply were changed as shown in Table 4.

[0270]

[0271] As can be seen from a comparison of the yields in Reference Examples 5 to 7, it was shown that the yield of formate can be improved by extending the residence time even in the continuous process.

[0272] [Confirmation of the Effect of Extended Residence Time in the First Reaction Step and Change in Yield Over Time] (Reference Example 8) In Reference Example 8, the same apparatus (FIG. 3) as in Reference Examples 1 to 7 was used. Under a nitrogen gas atmosphere, 60 mL of a 2 mol / L aqueous potassium bicarbonate solution was prepared as the aqueous phase. Under a nitrogen gas atmosphere, 60 mL of a toluene solution containing Catalyst 1 (60 μmol / L), methyltrioctylammonium chloride (54 mmol / L) as a phase transfer catalyst, and Irgafos 168 (BASF, 6 mmol / L) as an antioxidant was prepared as the organic phase. 20 mL of the aqueous potassium bicarbonate solution (aqueous phase) and 20 mL of the toluene solution (organic phase) were charged into the reactor. The remaining aqueous phase was transferred to one of two containers connected to the reactor by piping, and the remaining organic phase was transferred to the other. Pumps were prepared to transport these solutions to the reactor at a constant rate. Another pump was also prepared so that the reaction solution could be withdrawn from the reactor at a constant rate into the recovery container 300. The solution in the reactor was maintained at 90°C for 90 minutes while stirring at 800 rpm. Subsequently, the reaction solution was withdrawn from the reactor while the aqueous phase and organic phase were sent from the above-mentioned respective containers to the reactor so that the residence time was 90 minutes, and the inside of the reactor was brought into a steady state.

[0273] Ninety minutes after the start of the solution transfer, the transfer was temporarily stopped, and the reaction solution (fraction 1) was removed from the recovery container 300. The aqueous phase 220 and the organic phase 210 were separated and recovered, and their volumes were measured using a measuring cylinder. Using this aqueous phase 220, the yield of formate was calculated according to formula (3).

[0274] Five minutes after the liquid supply was stopped, the liquid supply of the aqueous and organic phases to the reactor and the withdrawal of the reaction liquid from the reactor were resumed so that the residence time was 90 minutes, and the reactor was brought to a steady state. When the prepared aqueous and organic phases were gone, the liquid supply was stopped, the reactor was cooled to room temperature, and then the pressure was carefully released. The atmosphere in the reactor was replaced with nitrogen gas. Under a nitrogen gas atmosphere, the reaction liquid in the recovery container 300 (fraction 2) and the reaction liquid in the reactor (fraction 3) were separately removed, and the aqueous and organic phases were separated. The volumes of the organic and aqueous phases were measured using a measuring cylinder. The yield of formate was calculated for each aqueous phase according to formula (3).

[0275] Table 5 shows the volumes of the organic and aqueous phases of each fraction collected in Reference Example 8, and the yield of formate determined for each aqueous phase.

[0276]

[0277] As can be seen from a comparison of the yields of fractions 2 and 3 in Table 5, the yield of formate contained in the solution recovered from the reactor by the pump during the period from 90 minutes after the start of the liquid feed to the end of the liquid feed was comparable to the yield of formate contained in the solution recovered from the reactor after the end of the liquid feed, confirming that the flow reaction had reached a steady state 90 minutes after the start of the liquid feed.

[0278] Example 7 In Example 7 and the following Examples 8 to 10, the apparatus shown in FIG. 4 was used, as in Examples 4 to 6. Under a nitrogen gas atmosphere, 60 mL of a 2 mol / L potassium bicarbonate aqueous solution was prepared as the aqueous phase. Under a nitrogen gas atmosphere, 60 mL of a toluene solution containing Catalyst 1 (60 μmol / L), methyltrioctylammonium chloride (54 mmol / L) as a phase transfer catalyst, and Irgafos 168 (BASF, 6 mmol / L) as an antioxidant was prepared as the organic phase. 20 mL of the potassium bicarbonate aqueous solution (aqueous phase) and 20 mL of the toluene solution (organic phase) were charged into the reactor. Two vessels connected to the reactor by piping were used: one to transfer the remaining aqueous phase, and the other to transfer the remaining organic phase. Pumps were prepared to transport these liquids to the reactor at a constant rate. Another pump was also prepared to withdraw the reaction liquid from the reactor to a collection vessel 300 at a constant rate. The solution in the reactor was maintained at 90° C. for 90 minutes while stirring at 800 rpm. Subsequently, the reaction solution was extracted from the reactor while the aqueous phase and the organic phase were fed from the respective vessels to the reactor so that the residence time of the solution in the reactor was 90 minutes, and the inside of the reactor was brought to a steady state.

[0279] Ninety minutes after the start of the solution transfer, the transfer was temporarily stopped, and only the aqueous phase 220 was recovered from the reaction solution (fraction 1) in the recovery container 300, and its volume was measured using a measuring cylinder. Using this aqueous phase, the yield of formate was calculated according to formula (3). The organic phase 210 was stored under a nitrogen atmosphere.

[0280] Five minutes after the liquid supply was stopped, the liquid supply of the aqueous phase and the organic phase to the reactor and the withdrawal of the reaction liquid from the reactor were resumed so that the residence time was 90 minutes, and the inside of the reactor was brought to a steady state. When the prepared aqueous phase and the organic phase were gone, the liquid supply was stopped, the reactor was cooled to room temperature, and then the pressure was carefully released.

[0281] The atmosphere inside the reactor was purged with nitrogen gas. Under a nitrogen gas atmosphere, only the aqueous phase was removed from the reaction solution (fraction 2) in the recovery container 300 and the reaction solution (fraction 3) in the reactor, and the volume was measured using a measuring cylinder. The yield of formate was calculated for each aqueous phase according to formula (3). All of the organic phases from fractions 1 to 3 were combined and placed in an empty pressure-resistant container (not shown), and the volume was increased to 60 mL with toluene. The container was then left to stand at room temperature for 20 hours under a hydrogen gas gauge pressure of 0.6 MPa and stored.

[0282] Under a nitrogen gas atmosphere, 60 mL of a 2 mol / L aqueous potassium bicarbonate solution was prepared as a new aqueous phase. 20 mL of the organic phase after storage and 20 mL of the above aqueous phase were added to the reactor. The remaining aqueous phase was transferred to one of two containers connected to the reactor by piping, and the remaining organic phase was transferred to the other. A pump was prepared to transport these to the reactor at a constant rate. Another pump was also prepared to extract the reaction solution from the reactor to the recovery container 300 at a constant rate. Then, for the second reaction, stirring of the solution in the reactor was started at 800 rpm, hydrogen gas was introduced into the reactor up to 5 MPa, and the temperature was raised to 90°C and maintained for 90 minutes. The aqueous and organic phases were then transferred from each container to the reactor so that the residence time was 90 minutes, while the reaction solution was extracted from the reactor, allowing the reactor to reach a steady state.

[0283] Ninety minutes after the start of the solution transfer, the transfer was temporarily stopped, and only the aqueous phase 220 was recovered from the reaction solution (fraction 4) in the recovery container 300, and its volume was measured using a measuring cylinder. Using this aqueous phase, the yield of formate was calculated according to formula (3). The organic phase 210 was stored under a nitrogen atmosphere.

[0284] Five minutes after the liquid supply was stopped, the liquid supply of the aqueous phase and the organic phase to the reactor and the withdrawal of the reaction liquid from the reactor were resumed so that the residence time was 90 minutes, and the inside of the reactor was brought to a steady state. When the prepared aqueous phase and the organic phase were gone, the liquid supply was stopped, the reactor was cooled to room temperature, and then the pressure was carefully released.

[0285] The atmosphere in the reactor was replaced with nitrogen gas. Under a nitrogen gas atmosphere, the reaction solution in the recovery container 300 (fraction 5) and the reaction solution in the reactor (fraction 6) were removed, and the aqueous and organic phases were separated for each. The yield of formate in the second reaction was calculated for each aqueous phase by the method described above, in the same manner as in the first reaction.

[0286] Table 6 shows the volumes of the organic and aqueous phases of each fraction collected in the first and second reactions in Example 7, and the yields of formate determined for each aqueous phase.

[0287]

[0288] As can be seen from the comparison of the yields in the first and second reactions shown in Table 6, it was found that the organic phase could be reused once while maintaining the same level of formate yield as in the first reaction.

[0289] Example 8: Under a nitrogen gas atmosphere, 60 mL of a 2 mol / L potassium bicarbonate aqueous solution was prepared as the aqueous phase. Under a nitrogen gas atmosphere, 60 mL of a toluene solution containing catalyst 1 (60 μmol / L), methyltrioctylammonium chloride (54 mmol / L) as a phase transfer catalyst, and Irgafos 168 (BASF, 6 mmol / L) as an antioxidant was prepared as the organic phase. 20 mL of the potassium bicarbonate aqueous solution (aqueous phase) and 20 mL of the toluene solution (organic phase) were charged into the reactor. Two vessels connected to the reactor by piping were used: one to transfer the remaining aqueous phase, and the other to transfer the remaining organic phase. Pumps were prepared to transport these liquids to the reactor at a constant rate. Another pump was also prepared to withdraw the reaction liquid from the reactor to the recovery vessel 300 at a constant rate. The solution in the reactor was stirred at 800 rpm and maintained at 90°C for 90 minutes. Next, the aqueous and organic phases were transferred from the vessels to the reactor so that the residence time was 90 minutes, while the reaction mixture was withdrawn from the reactor, and the reactor was brought to a steady state. When the prepared aqueous and organic phases were gone, the transfer was stopped, the reactor was cooled to room temperature, and then the pressure was carefully released. The atmosphere in the reactor was replaced with nitrogen gas.

[0290] Under a nitrogen gas atmosphere, the aqueous phase was removed from the reaction solution (fraction 1) in the recovery container 300 and the reaction solution (fraction 2) in the reactor, and the volume was measured using a measuring cylinder. For each aqueous phase, the yield of formate was calculated according to formula (3). All of the organic phases from fractions 1 and 2 were combined and placed in an empty pressure-resistant container (not shown), and the container was filled up to 60 mL with toluene. The container was then left to stand at room temperature for 20 hours under a hydrogen gas gauge pressure of 0.6 MPa and stored.

[0291] Under a nitrogen gas atmosphere, 60 mL of a 2 mol / L aqueous potassium bicarbonate solution was prepared as a new aqueous phase. 20 mL of the organic phase after storage and 20 mL of the aqueous phase were added to the reactor, and the remaining organic and aqueous phases were transferred to a container in the same manner as in the first reaction, and a pump was prepared. Subsequently, for the second reaction, the liquids were pumped in the same manner as in the first reaction, and the reactor was brought to a steady state. When the prepared aqueous and organic phases were gone, the liquid pumping was stopped, the reactor was cooled to room temperature, and then the pressure was carefully released. The atmosphere in the reactor was replaced with nitrogen gas.

[0292] Under a nitrogen gas atmosphere, the reaction solution (fraction 3) in the recovery container 300 and the reaction solution (fraction 4) in the reactor were removed, and each was separated into an aqueous phase and an organic phase. The yield of formate in the second reaction was calculated for each aqueous phase by the method described above, in the same manner as in the first reaction.

[0293] Table 7 shows the aqueous phase volumes of the fractions collected in the first and second reactions in Example 8, and the yields of formate determined for each aqueous phase.

[0294]

[0295] Fraction 1 in Example 8 is synonymous with the sample in which fractions 1 and 2 in Example 7 are combined, and fraction 3 in Example 8 is synonymous with the sample in which fractions 4 and 5 in Example 7 are combined.

[0296] Example 9 The first and second reactions were carried out in the same manner as in Example 8. Next, all of the organic phases from fractions 3 and 4 recovered in the second reaction were combined and placed in an empty pressure vessel (not shown), and the volume was adjusted to 60 mL with toluene. The vessel was then allowed to stand at room temperature for 20 hours under a hydrogen gas gauge pressure of 0.6 MPa and stored.

[0297] Under a nitrogen gas atmosphere, 60 mL of a 2 mol / L aqueous potassium bicarbonate solution was prepared as a new aqueous phase. 20 mL of the organic phase after storage and 20 mL of the aqueous phase were added to the reactor, and the remaining organic and aqueous phases were transferred to a container in the same manner as in the first reaction, and a pump was prepared. Subsequently, for the third reaction, the liquid was pumped in the same manner as in the first reaction, and the reactor was brought to a steady state. When the prepared aqueous and organic phases were gone, the liquid pumping was stopped, the reactor was cooled to room temperature, and then the pressure was carefully released. The atmosphere in the reactor was replaced with nitrogen gas.

[0298] Under a nitrogen gas atmosphere, the reaction solution (fraction 5) in the recovery container 300 and the reaction solution (fraction 6) in the reactor were removed, and each was separated into an aqueous phase and an organic phase. For each aqueous phase, the yield of formate in the third reaction was calculated according to formula (3).

[0299] Table 8 shows the volume of the aqueous phase of each fraction collected in the first to third reactions in Example 9 and the yield of formate determined for each aqueous phase.

[0300]

[0301] As can be seen from Table 8, the organic phase containing the catalyst can be reused twice while maintaining good formate yield.

[0302] Example 10 The first to third reactions were carried out in the same manner as in Example 9. Next, all of the organic phases of fractions 5 and 6 recovered in the third reaction were combined and placed in an empty pressure-resistant container (not shown), and the container was filled up to 60 mL with toluene and then allowed to stand at room temperature for 20 hours under a hydrogen gas gauge pressure of 0.6 MPa for storage.

[0303] Under a nitrogen gas atmosphere, 60 mL of a 2 mol / L aqueous potassium bicarbonate solution was prepared as a new aqueous phase. 20 mL of the organic phase after storage and 20 mL of the aqueous phase were added to the reactor, and the remaining organic and aqueous phases were transferred to a container in the same manner as in the first reaction, and a pump was prepared. Subsequently, for the fourth reaction, the liquid was pumped in the same manner as in the first reaction, and the reactor was brought to a steady state. When the prepared aqueous and organic phases were gone, the liquid pumping was stopped, the reactor was cooled to room temperature, and then the pressure was carefully released. The atmosphere in the reactor was replaced with nitrogen gas.

[0304] Under a nitrogen gas atmosphere, the aqueous phase was removed from the reaction solution in the recovery container 300 (Fraction 7) and the reaction solution in the reactor (Fraction 8), and the volume was measured using a measuring cylinder. For each aqueous phase, the yield of formate in the fourth reaction was calculated according to equation (3). All of the organic phases from Fractions 7 and 8 were combined and placed in an empty pressure-resistant container (not shown), and the volume was increased to 60 mL with toluene. The container was then allowed to stand at room temperature for 20 hours under a hydrogen gas gauge pressure of 0.6 MPa and stored.

[0305] Under a nitrogen gas atmosphere, 60 mL of a 2 mol / L aqueous potassium bicarbonate solution was further prepared as a new aqueous phase. 20 mL of the organic phase after storage and 20 mL of the aqueous phase were added to the reactor, and the remaining organic and aqueous phases were transferred to a container in the same manner as in the first reaction, and a pump was prepared. Subsequently, for the fifth reaction, the liquid was pumped in the same manner as in the first reaction, and the reactor was brought to a steady state. When the prepared aqueous and organic phases were gone, the liquid pumping was stopped, the reactor was cooled to room temperature, and then the pressure was carefully released. The atmosphere in the reactor was replaced with nitrogen gas.

[0306] Under a nitrogen gas atmosphere, the reaction solution in the recovery vessel 300 (fraction 9) and the reaction solution in the reactor (fraction 10) were removed, and each was separated into an aqueous phase and an organic phase. For each aqueous phase, the yield of formate in the fifth reaction was calculated according to formula (3).

[0307] Table 9 shows the volume of the aqueous phase of each fraction collected in the first to fifth reactions in Example 10, and the yield of formate determined for each aqueous phase.

[0308]

[0309] As can be seen from Table 9, the organic phase containing the catalyst could be reused four times while maintaining good formate yield.

[0310] According to the method for recycling a catalyst and the method for producing an organic compound of the present embodiment, for example, a target organic compound can be produced efficiently at low cost.

Claims

1. A method for recycling a catalyst, comprising: a first reaction step of reacting a first starting compound using a catalyst; a separation step of separating a catalyst solution containing the catalyst from the reaction liquid obtained in the first reaction step; a storage step of storing the catalyst solution under a pressurized atmosphere; and a second reaction step of reacting a second starting compound using the catalyst solution after storage, wherein the catalyst is at least one selected from the group consisting of metal complexes containing a metal M and a ligand represented by the following general formula (1B) and salts thereof, and the pressurized atmosphere consists essentially of a gas other than oxygen. (In general formula (1B), X represents an atomic group containing a typical element of Groups 13 to 15 that can be coordinated to the metal M; each Y independently represents an atomic group containing a typical element of Groups 14 to 16 that can be coordinated to the metal M; and each Q independently represents a bridge structure that connects Y and X and contains a typical element of Groups 14 to 16.) 2. The method for recycling a catalyst according to claim 1, wherein the gas comprises at least one selected from the group consisting of hydrogen and nitrogen.

3. The method for recycling a catalyst according to claim 2, wherein the gas comprises hydrogen.

4. The method for reusing a catalyst according to claim 1, wherein the pressure of the gas in the pressurized atmosphere is 0.2 MPa or more and 20 MPa or less in gauge pressure.

5. The method for recycling a catalyst according to claim 1, wherein in the catalyst, X and two Ys in general formula (1B) are coordinated to the metal M.

6. The method for reusing a catalyst according to claim 1, wherein the catalyst is at least one selected from the group consisting of a metal complex represented by the following general formula (1A), its tautomer, stereoisomer, and salt thereof: (In general formula (1A), X represents an atomic group containing a typical element of Groups 13 to 15 that can be coordinated to M; each Q independently represents a bridged structure that contains a typical element of Groups 14 to 16 and connects Y and X; each Y independently represents an atomic group containing a typical element of Groups 14 to 16 that can be coordinated to M; M represents a metal atom; Z represents an anionic ligand; n represents 0 to 3; and when a plurality of Ls are present, each independently represents a neutral or anionic ligand.) 7. The method for reusing a catalyst according to claim 6, wherein the metal complex represented by the general formula (1A) is a metal complex represented by the following general formula (2A): (In general formula (2A), X1 represents a heteroaromatic ring formed together with two carbon atoms and a nitrogen atom, which may have a substituent, or may be bonded to another substituent to form a ring; each Q1 independently represents CH2, NH, or O, and CH2 and NH may further have a substituent; each Y1 independently represents a phosphorus atom or a nitrogen atom; each R independently represents an alkyl group, an aryl group, or an aralkyl group, which may further have a substituent; M represents a metal atom; Z represents an anionic ligand; n represents 0 to 3; and when a plurality of Ls are present, each independently represents a neutral or anionic ligand.) 8. The method for reusing a catalyst according to claim 7, wherein the metal complex represented by the general formula (2A) is a metal complex represented by the following general formula (3A): (In general formula (3A), R represents a hydrogen atom or an alkyl group; each A independently represents CH, CR, or N, and R represents an alkyl group, an aryl group, an aralkyl group, an amino group, a hydroxy group, or an alkoxy group; each Q independently represents CH, NH, or O, and CH and NH may further have a substituent; Y represents a phosphorus atom or a nitrogen atom; each R independently represents an alkyl group, an aryl group, or an aralkyl group, which may further have a substituent; M represents a metal atom; Z represents an anionic ligand; n represents 0 to 3; and when a plurality of Ls are present, each independently represents a neutral or anionic ligand.) 9. The method for recycling a catalyst according to claim 1, wherein said metal M is ruthenium.

10. The method for reusing a catalyst according to claim 1, wherein the reaction in the first reaction step is carried out in the presence of a solvent containing an organic solvent and an aqueous solvent, in a two-phase system in which the organic solvent and the aqueous solvent are separated.

11. The method for reusing a catalyst according to claim 10, wherein in the first reaction step, the organic phase containing the organic solvent contains the catalyst, and the aqueous phase containing the aqueous solvent contains the first starting compound.

12. The method for recycling a catalyst according to claim 1, wherein the reaction in the first reaction step is a hydrogenation reaction of the first starting compound with hydrogen, and a hydride of the first starting compound is obtained by the reaction.

13. The method for recycling a catalyst according to claim 12, wherein the first starting compound is at least one selected from the group consisting of carbon dioxide, bicarbonate, and carbonate, and a formate is obtained from the first starting compound in the first reaction step.

14. A method for producing an organic compound using the catalyst recycling method according to any one of claims 1 to 13, comprising producing an organic compound from the first starting compound and producing an organic compound from the second starting compound.

15. A method for storing a catalyst, comprising storing a catalyst solution containing a catalyst under a pressurized atmosphere, wherein the catalyst is at least one selected from the group consisting of metal complexes containing a metal M and a ligand represented by the following general formula (1B) and salts thereof, and the pressurized atmosphere consists essentially of a gas other than oxygen. (In general formula (1B), X represents an atomic group containing a typical element of Groups 13 to 15 that can be coordinated to the metal M; each Y independently represents an atomic group containing a typical element of Groups 14 to 16 that can be coordinated to the metal M; and each Q independently represents a bridge structure that connects Y and X and contains a typical element of Groups 14 to 16.)

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