JP4496340B2 - Catalyst capable of electrochemical regeneration and method for reducing organic compounds using the same - Google Patents

Description

  The present invention relates to an electrochemically reproducible catalyst, a method for producing the same, and a method for reducing an organic compound using the catalyst.

In recent years, there has been a social demand for effective use of carbon dioxide gas in relation to environmental problems. The most basic two-electron reduction products of carbon dioxide are CO (formula A) and HCOOH (formula B).

On the other hand, water gas transfer reaction, which is an industrial hydrogen production process, includes H ₂ generation by CO oxidation (C formula) and H ₂ generation by decomposition of HCOO ⁻ (D formula) generated by the reaction of CO and OH ⁻ (E Formula) is known.

  Water gas transfer reactions (C and E above) spontaneously proceed due to exothermic reactions, while carbon dioxide reduction reactions (A and B above) are endothermic reactions, so they can be externally applied by electricity or light. It is necessary to inject energy into the reaction system to advance the reaction. Therefore, an appropriate catalyst has been desired to enable both reactions to proceed with almost the same reaction mechanism.

On the other hand, the following NAD ⁺ / NADH type reaction formula is known.
[In the above formula, R is adenine nucleoside or adenine dinucleoside phosphate. ]

However, the model compound having such a pyridinium structure (R '= alkyl group), the coupling reaction by receiving one electron reduction proceeds with priority, H for the reduction of the substrate ^- to generate the This was not possible (see the reaction scheme below), and it was unstable to acids and bases, so that it was not suitable for use as a catalyst.
[In the above formula, R ′ represents an alkyl group. ]

  Therefore, an electrochemically reproducible catalyst that enables reduction of an organic compound containing a carbonyl group such as carbon dioxide has not been obtained yet.

  An object of the present invention is to provide a catalyst that is useful for reduction of an organic compound, particularly an organic compound containing a carbonyl group, and is electrochemically reproducible.

The present inventors have found a novel metal complex having a redox mechanism of NAD ⁺ / NADH system, and found that by using this complex, an organic compound containing a carbonyl group can be reduced under electroreduction conditions. Completed the invention.

That is, in the first aspect of the present invention, there is provided an intermediate for catalyst that is capable of electrochemical regeneration represented by the following formula (1a).
[Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁶ and R ⁷ are each independently the same or different and represent a hydrogen atom, a C ₁ -C ₁₀ alkyl group or a C ₆ -C ₁₀ An aryl group. ]

The second aspect of the present invention provides a catalyst capable of electrochemical regeneration represented by the following formula (1b).
[Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁶ and R ⁷ are each independently the same or different and represent a hydrogen atom, a C ₁ -C ₁₀ alkyl group or a C ₆ -C ₁₀ An aryl group, R ⁵ is a hydrogen atom or a C ₁ -C ₁₀ alkyl group, and M is a monovalent to hexavalent transition metal; ]

In the third aspect of the present invention, an aspect of the method for producing a catalyst according to the second aspect of the present invention, that is, in the presence of a base, a pyridine derivative represented by the following formula (2),
[Wherein R ¹ , R ² , R ³ and R ⁴ have the above-mentioned meanings. ] A quinoline derivative represented by the following formula (3);
[Wherein R ⁶ and R ⁷ have the above-mentioned meanings. The first step for obtaining a reaction product, the second step for coordinating the reaction product obtained in the first step to the transition metal M, the complex obtained in the second step, and the following formula A cation represented by (4)
[Wherein R ⁵ has the above-mentioned meaning. ] The manufacturing method of the catalyst which can perform the electrochemical reproduction | regeneration shown by the said Formula (1b) characterized by including the 3rd process made to react is provided.

  The fourth aspect of the present invention is a method for reducing an organic compound using the catalyst according to the second aspect of the present invention, that is, in the presence of a catalyst capable of electrochemical regeneration represented by the above formula (1b). A reduction method for reducing an organic compound under electrochemical conditions under acidic conditions is provided.

In the first embodiment of the present invention, R ¹ , R ² , R ³ , R ⁴ , R ⁶ and R ⁷ are preferably hydrogen atoms.
In the second aspect, the third aspect and the fourth aspect of the present invention, it is preferable that R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are hydrogen atoms.

  In the second, third and fourth aspects of the present invention, it is preferable that M is a metal capable of coordinating 2,2'-bipyridine.

  In the fourth aspect of the present invention, the organic compound preferably has a carbonyl group.

  The present invention makes it possible to catalytically reduce organic compounds such as ketones. This makes it possible to efficiently store difficult-to-store electrical energy in the state of organic matter, and is expected to be applied in the fields of clean energy and green chemistry.

In the first aspect of the present invention, an intermediate for a catalyst capable of electrochemical regeneration represented by the following formula (1a) is provided.

In the above formula, R ¹ , R ² , R ³ , R ⁴ , R ⁶ and R ⁷ are each independently the same or different and represent a hydrogen atom, a C ₁ -C ₁₀ alkyl group or C ₆ -C _10. An aryl group.

In the present specification, "C ₁ -C ₁₀ alkyl group" is preferably C ₁ -C ₆ alkyl group, more preferably a C ₁ -C ₃ alkyl group. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, or hexyl.

In the present specification, examples of the “C ₆ -C ₁₀ aryl group” include, but are not limited to, phenyl, 1-naphthyl, 2-naphthyl, or indenyl.

In the first embodiment of the present invention, R ¹ , R ² , R ³ , R ⁴ , R ^6, and R ⁷ are preferably hydrogen atoms from the viewpoint of ease of synthesis and steric factors.

In the second aspect of the present invention, a catalyst capable of electrochemical regeneration represented by the following formula (1b) is provided.

In the above formula, the description of R ¹ , R ² , R ³ , R ⁴ , R ⁶ and R ⁷ is the same as that described in the first aspect of the present invention.

Further, in the above formula (1b), R ⁵ is a hydrogen atom or a C ₁ -C ₁₀ alkyl group.
In the second embodiment of the present invention, R ⁵ is preferably a hydrogen atom from the viewpoint of the stability of the product and the convenience of reaction conditions.

In the above formula (1b), M is a monovalent to hexavalent transition metal.
In the second aspect of the present invention, M is capable of coordinating the ligand and does not redox the metal during the reaction (the metal redox potential is significantly different from the redox level of the ligand). is important.
M is preferably a metal to which 2,2′-bipyridine can be coordinated, and specifically, ruthenium is most preferable.

In the second aspect of the present invention, M may have a ligand.
Examples of ligands possessed by M include supporting ligands such as amines, halogen atoms, phosphines, and phosphites. In addition, ligands such as nitriles, ketones, and water that can be eliminated during the reduction reaction are included. You may have.

  The amine may be an aromatic amine such as pyridine, bipyridine, terpyridyl, or quinoline as a ligand, an alkylene diamine such as ethylene diamine, or an N, N, N ′, N′-tetraalkylethylene diamine. It may be an aliphatic amine such as N, N, N ′, N′-tetrasubstituted alkylenediamine, or a trisalkylenediamine such as trisethylenediamine.

  The nitrile may be alkyl cyanide or aryl cyanide as a ligand, but is preferably acetonitrile.

  The ketone is preferably acetone as a ligand.

Phosphine is diarylphosphine such as diphenylphosphine, triarylphosphine such as triphenylphosphine, trialkylphosphine such as triethylphosphine, alkyldiarylphosphine, dialkylarylphosphine, 1,2-bis (diphenylphosphino) ethane. Α, ω-bis (diarylphosphino) alkanes such as P, P, P ′, P ′, P ″, P ″ -P, P, P ′, P ′, such as P ″ -hexaphenyl-trisethylenetetraphosphine, P ″, P ″ -hexasubstituted-trisalkylenetetraphosphine and the like may be used.
Phosphites are the same as phosphines.

  In the second embodiment of the present invention, M preferably has a ligand such as an amine, a nitrile, a ketone, or a halogen atom, and 2,2′-bipyridine, 2,2 ′: 6 ′, 2 ″ -terpyridyl, It is more preferable to have a ligand such as acetone, water, and acetonitrile.

The catalyst according to the second aspect of the present invention is more preferably a complex shown below, for example.
[In the formula, “Solv.” Means a solvent (water, acetone, acetonitrile, etc.). ]

In the third aspect of the present invention, an aspect of a method for producing a catalyst according to the second aspect of the present invention is provided. That is, in the presence of a base, the pyridine derivative represented by the following formula (2) and the quinoline derivative represented by the following formula (3) are reacted to obtain a reaction product, which is obtained in the first step. The second step of coordinating the reaction product to the transition metal M, and the third step of reacting the complex obtained in the second step with a cation represented by the following formula (4) A method for producing a catalyst capable of electrochemical regeneration represented by the following formula (1b) is provided.
[Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and M have the above-mentioned meanings. ]

In the third aspect of the present invention, a pyridine derivative represented by the following formula (2) is used.

In the above formula, the description of R ¹ , R ² , R ³ and R ⁴ is the same as that described in the first aspect of the present invention.

In the third aspect of the present invention, a quinoline derivative represented by the following formula (3) is used.

In the above formula, the explanation about R ⁶ and R ⁷ is the same as that explained in the first aspect of the present invention.

In the third aspect of the present invention, the reaction product is obtained by reacting the pyridine derivative represented by the above formula (2) and the quinoline derivative represented by the above formula (3) in the presence of a base (first step). .
In the first step of the third aspect of the present invention, examples of the base include sodium hydroxide, potassium hydroxide, and base catalysts such as alkoxide produced by dissolving them in alcohol, and alkoxide is used. It is preferable.

  In the first step of the third aspect of the present invention, it is preferable to use 0.1 mol to 10 mol of the quinoline derivative represented by the above formula (3) with respect to 1 mol of the pyridine derivative represented by the above formula (2). , 0.5 mol to 5 mol is more preferable, 0.8 mol to 2 mol is more preferable, and about 1 mol is particularly preferable.

  In the first step of the third aspect of the present invention, typically, a base is dropped into a solution of the pyridine derivative represented by the above formula (2) and the quinoline derivative represented by the above formula (3), followed by precipitation. The resulting solid is purified to obtain a reaction product.

In the first step of the third aspect of the present invention, a coupling reaction occurs by reacting a pyridine derivative represented by the following formula (2) with a quinoline derivative represented by the following formula (3) in the presence of a base. The benzonaphthyridine derivative represented by the following formula (1a), which is an intermediate according to the first embodiment of the present invention, is considered to be obtained as a reaction product.
[Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁶ and R ⁷ have the above-mentioned meanings. ]
For example, when R ¹ , R ² , R ³ , R ⁴ , R ⁶ and R ⁷ are all hydrogen atoms and ethoxide is used as the base, the following reaction mechanism is proposed. However, this reaction mechanism is only a hypothesis, and the present invention is not limited to this reaction mechanism.

In the first step of the third aspect of the present invention, the reaction is preferably performed in a temperature range of −100 ° C. to 100 ° C., more preferably in a temperature range of −50 ° C. to 50 ° C., and further preferably 20 ° C. to It is performed in a temperature range of 30 ° C.
In the first step of the third aspect of the present invention, the pressure is preferably normal pressure.

  In the first step of the third aspect of the present invention, the solvent is preferably a solvent that can dissolve the pyridine derivative represented by the above formula (2) and the quinoline derivative represented by the above formula (3). As the solvent, an aliphatic or aromatic organic solvent is used. Alcohol solvents such as methanol or ethanol; ether solvents such as tetrahydrofuran or diethyl ether; halogenated hydrocarbons such as methylene chloride; halogenated aromatic hydrocarbons such as o-dichlorobenzene; N, N-dimethyl Amides such as formamide; sulfoxides such as dimethyl sulfoxide; aromatic hydrocarbons such as benzene and toluene are used. From the viewpoint that the base is preferably an alkoxide, an alcohol solvent is preferably used.

  In the first step of the third aspect of the present invention, the reaction time is preferably 8 hours to 7 days, more preferably 24 hours to 5 days, and further preferably 2 days to 4 days. Particularly preferred is about 3 days.

In the third aspect of the present invention, subsequently, the reaction product obtained in the first step is coordinated to the transition metal M (second step).
The description of the transition metal M is the same as that described in the second aspect of the present invention.

  In the second step of the third aspect of the present invention, typically, the solution of the metal salt or metal complex containing the transition metal M is silver in order to remove the halogen when the metal salt or metal complex contains a halogen atom. Add compound solution and stir. After removing the precipitated silver salt, the reaction product obtained in the first step can be coordinated with the transition metal M by adding and stirring the reaction product obtained in the first step. .

As the metal salt used in the second step of the third aspect of the present invention, a salt of inorganic acid such as hydrochloric acid or sulfuric acid and a salt of organic acid such as acetic acid or methanesulfonic acid can be used. Examples thereof include ruthenium halides such as ruthenium chloride, zinc halides, and copper halides.

  The metal complex used in the second step of the third aspect of the present invention is preferably a ruthenium complex. In this case, examples of the ligand include amine, nitrile, halogen atom, water, ketone, phosphine, and phosphite. The metal complex used in the second step of the third aspect of the present invention is preferably dichlorobis (2,2′-bipyridyl) ruthenium, trichloro (2,2 ′: 6 ′, 2 ″ -terpyridyl) ruthenium, etc. Can be mentioned.

  In the second step of the third aspect of the present invention, it is preferable to use 0.1 mol to 10 mol of the metal salt or metal complex containing the transition metal M with respect to 1 mol of the reaction product obtained in the first step. It is more preferable to use 0.5 mol to 5 mol, more preferable to use 0.8 mol to 2 mol, and particularly preferable to use about 1 mol.

In the second step of the third aspect of the present invention, a silver compound is preferably used from the viewpoint of removing halide ions.
Preferred examples of the silver compound include silver hexafluorophosphate, silver tetrafluoroborate, and silver trifluoromethanesulfonate.

  In the second step of the third aspect of the present invention, the silver compound is preferably used in an amount of 0.1 mol to 10 mol, based on 1 mol of halogen in the reaction product obtained in the first step, and 0.5 mol It is more preferable to use ˜5 mol, more preferably 0.8 mol to 2 mol, and particularly preferably about 1 mol.

In the second step of the third aspect of the present invention, an appropriate metal salt or metal complex containing the reaction product obtained in the first step and a transition metal M from which a halogen atom has been removed by a silver compound if it contains a halogen atom It is considered that a complex represented by the following formula (5) can be obtained by reacting with:
[Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and M have the above-mentioned meanings. ]

In the second step of the third aspect of the present invention, the reaction is preferably performed in a temperature range of 0 ° C to 100 ° C, more preferably in a temperature range of 30 ° C to 90 ° C, and further preferably 50 ° C to 80 ° C. And particularly preferably at about 70 ° C.
In the second step of the third aspect of the present invention, the pressure is preferably normal pressure.

  As a solvent used at the 2nd process of the 3rd mode of the present invention, when using a metal salt or metal complex containing transition metal M, and a silver compound, a solvent which can dissolve a silver compound is preferred. As the solvent, an aliphatic or aromatic organic solvent is used. Alkoxy alcohol solvents such as 2-methoxyethanol; ether solvents such as tetrahydrofuran or diethyl ether; halogenated hydrocarbons such as methylene chloride; halogenated aromatic hydrocarbons such as o-dichlorobenzene; N, N -Amides such as dimethylformamide; Sulfoxides such as dimethyl sulfoxide; Aromatic hydrocarbons such as benzene and toluene are used.

In the second step of the third aspect of the present invention, when a silver compound is used, the reaction time between the metal salt or metal complex containing the transition metal M and the silver compound is preferably 30 minutes to 10 hours. The time is more preferably 5 to 5 hours, further preferably 1 to 3 hours, and particularly preferably about 2 hours.
In the second step of the third aspect of the present invention, the reaction time when the reaction mixture obtained in the first step is added and then reacted is preferably 1 hour to 1 day, and preferably 5 hours to 20 hours. More preferably, it is more preferably 10 hours to 14 hours, and particularly preferably about 12 hours.

In the third aspect of the present invention, subsequently, the complex obtained in the second step is reacted with a cation represented by the following formula (4) (third step).
In the above formula, description of R ⁵ is the same as that described in the second aspect of the present invention.

  In the third step of the third aspect of the present invention, it is preferable to use an excess amount of the cation represented by the above formula (4) with respect to 1 mol of the complex obtained in the second step.

  In the third step of the third aspect of the present invention, typically, the complex represented by the above formula (1b) is obtained by reacting the solution of the complex obtained in the second step with a protonating agent or an alkylating agent. .

  Examples of the protonating agent used in the third step of the third aspect of the present invention include various acids.

  In this specification, examples of the “acid” include organic acids and inorganic acids.

  In the present specification, the “organic acid” includes formic acid, acetic acid, trifluoroacetic acid, fumaric acid, oxalic acid, tartaric acid, maleic acid, citric acid, succinic acid, malic acid, methanesulfonic acid, benzenesulfonic acid, p- Examples include toluenesulfonic acid, lactic acid, and gluconic acid. Examples of the “inorganic acid” include hydrochloric acid, hydrobromic acid, nitric acid, sulfuric acid, carbonic acid, phosphoric acid, aluminate, and zirconic acid.

  The protonating agent used in the third step of the third aspect of the present invention is preferably acetic acid, phosphoric acid or the like.

  Examples of the alkylating agent used in the third step of the third aspect of the present invention include trialkyloxonium salts such as trimethyloxonium tetrafluoroborate, alkyl halides such as methyl iodide, alkyl triflates such as methyl triflate, etc. It is preferable to use trimethyloxonium tetrafluoroborate.

In the third step of the third aspect of the present invention, the reaction is preferably performed in a temperature range of 0 ° C to 100 ° C, more preferably in a temperature range of 30 ° C to 90 ° C, and further preferably 50 ° C to 80 ° C. And particularly preferably at about 70 ° C.
In the third step of the third aspect of the present invention, the pressure is preferably normal pressure.

  In the third step of the third aspect of the present invention, the solvent is preferably a solvent that can dissolve the complex obtained in the second step. As the solvent, an aliphatic or aromatic organic solvent is used. Alkoxy alcohol solvents such as 2-methoxyethanol; ether solvents such as tetrahydrofuran or diethyl ether; halogenated hydrocarbons such as methylene chloride; halogenated aromatic hydrocarbons such as o-dichlorobenzene; N, N -Amides such as dimethylformamide; Sulfoxides such as dimethyl sulfoxide; Aromatic hydrocarbons such as benzene and toluene are used.

  In the third step of the third aspect of the present invention, the reaction time is preferably 10 minutes to 5 hours, more preferably 20 minutes to 1 hour, and particularly preferably about 30 minutes.

  In the fourth aspect of the present invention, a method for reducing an organic compound using the catalyst according to the second aspect of the present invention, that is, in the presence of a catalyst capable of electrochemical regeneration represented by the above formula (1b), is acidic. A reduction method for reducing an organic compound under electrochemical conditions is provided.

In the fourth aspect of the present invention, the organic compound preferably has a carbonyl group. For example, the organic compound is reduced according to the following reaction formula.

In the above formula, A ¹ and A ² are each independently the same or different and may have a C _{1 to} C ₁₀ alkyl group which may have a substituent, or C which may have a substituent. ₆ is a -C ₁₀ aryl group.

In the fourth embodiment of the present invention, a substituent may be introduced into the “C ₁ -C ₁₀ alkyl group” and the “C ₆ -C ₁₀ aryl group” represented by A ¹ and A ² . As the substituent, for example, C ₁ -C ₁₀ alkyl group (e.g., methyl, ethyl, propyl, butyl, etc.), C ₁ -C ₁₀ alkoxy group (e.g., methoxy, ethoxy, propoxy, butoxy, etc.), C ₆ -C ₁₀ aryloxy group (e.g., phenyloxy, naphthyloxy, biphenyloxy, etc.), an amino group, a hydroxyl group, a halogen atom (e.g., fluorine, chlorine, bromine, iodine) and the like, or a silyl group. In this case, one or more substituents may be introduced at substitutable positions. When the number of substituents is 2 or more, each substituent may be the same or different.

In the fourth aspect of the present invention, A ¹ and A ² are preferably a C ₁ -C ₃ alkyl group, a C ₁ -C ₃ alkyl group having a halogen atom, or a phenyl group, and a methyl group, trifluoromethyl More preferably, it is a group or a phenyl group.
Good.

The reduction method according to the fourth aspect of the present invention typically proceeds according to the catalytic reduction reaction shown in FIG.
That is, the catalyst (oxidized type) represented by the formula (1b) is reduced by two electrons and one proton under acidic conditions and electrochemical conditions to be reduced (1b ′). The organic compound (7) is reduced by the transfer of hydride H ⁻ from the reduced form (1b ′) and becomes an organic compound (7 ′) under acidic conditions via the organic compound (7 ″). ') hydrido H ^- Return to oxidized (1b) by the release of.

In the fourth aspect of the present invention, the acidic condition is not particularly limited as long as protons are produced. For example, a buffer solution such as an acetic acid-sodium acetate buffer or a phosphoric acid-potassium dihydrogen phosphate buffer is used. It is preferable to use it. A mixed solvent of a buffer solution and acetone or the like may be used.
Moreover, as electrolyte added to a solvent, salts, such as sodium chloride and potassium phosphate, can be especially used without a restriction | limiting.

  In the fourth aspect of the present invention, the electrochemical reaction is preferably performed at a potential in the range of 0V to -2V, and the reaction is performed at a potential in the range of -0.8V to -1.2V. More preferred.

  Hereinafter, the present invention will be described based on examples. However, the present invention is not limited to the following examples.

All reactions were performed under a nitrogen atmosphere unless otherwise stated.
The source of each reagent used in the examples is shown below.

2-acetylpyridine Tokyo Chemical Ethanol (dehydration) Kanto Chemical Potassium Hydroxide Kanto Chemical Ammonium Chloride Kanto Chemical Ethyl Acetate Sodium Nacalai Tesque Sulfate Wako Pure Chemical
Al ₂ O ₃ (N) Super I ICN Biomedicals GmbH
Ruthenium chloride fluya metal
2,2'-bipyridine Tokyo Kasei
2,2 ': 6', 2 "-Terpyridine Aldrich
Silver hexafluorophosphate Aldrich
2-Methoxyethanol Nacalai Tesque Tetrafluoroborate Trimethyloxonium Aldrich
Acetonitrile Nacalai Tesque Diethyl Ether Nacalai Tesque
1,2-dichloroethane Tokyo Kasei acetone Nacalai Tesque
a, a, a-Trifluoroacetophenone Aldrich

¹ H NMR spectrum was measured with a JEOL GX-500 spectrometer.
GC (gas chromatograph) was measured with Shimadzu GC-14B.
GC-MS (mass spectrometry) was measured with Shimadzu GCMS-QP5050A.
ESI-MS (electrospray ionization mass spectrometry) was measured with Shimadzu LCMS-2020.

Example 1
6- (2-Pyridyl) benzo [b] -1,5-naphthyridine (pbn)
3-Aminoquinaldehyde (186 mg, 1.08 mmol) and 2-acetylpyridine (121 μL, 1.08 mmol) were suspended in 12 mL of ethanol, several drops of KOH in ethanol were added, and the mixture was allowed to stand in the dark for 3 days. An orange solid precipitated out. After 3 days, saturated aqueous ammonium chloride solution was added, extracted with ethyl acetate, and the organic layer was dried over sodium sulfate. The solvent was distilled off and the residue was purified with an alumina column (Al ₂ O ₃ (N) / EtOAc) to obtain the title compound. Yield 85.1 mg (31%).

¹ H MNR (500MHz, CDCl ₃ ): δ 9.08 (s, 1H), 8.90 (d, 1H, J (HH) = 9.2 Hz), 8.79 (d, 1H, J (HH) = 4.9 Hz), 8.72 ( d, 1H, J (HH) = 7.9 Hz), 8.63 (d, 1H, J (HH) = 9.2 Hz), 8.28 (d, 1H, J (HH) = 9.2 Hz), 8.12 (d, 1H, J (HH) = 9.2 Hz), 7.92 (t, 1H, J (HH) = 7.9 and 1.2 Hz), 7.85 (m, 1H), 7.61 (t, 1H, J (HH) = 7.3 Hz), 7.42 (m , 1H).

Example 2 (Preparation of Complex 1)
[Ru (pbn) (bpy) ₂ ] (PF ₆ ) ₂ (complex 1)
Dichlorobis (2,2'-bipyridyl) ruthenium ([RuCl ₂ (bpy) ₂ ]) (53 mg, 0.109 mmol) is dissolved in 20 mL of 2-methoxyethanol, and AgPF ₆ (60 mg, 0.237 mmol) of 2-methoxyethanol. The solution (5 mL) was added and stirred at 70 ° C. for 2 hours. After the precipitated AgCl was removed by Celite filtration, 6- (2-pyridyl) benzo [b] -1,5-naphthyridine (28 mg, 0.109 mmol) obtained in Example 1 was added and the mixture was added at 70 ° C. for 12 hours. Stir. After cooling to room temperature, the solution was concentrated to 1 mL and poured into aqueous NH ₄ PF ₆ solution. The precipitated solid was collected by filtration and dried to obtain the title compound. Yield 92 mg (88%). The X-ray crystal structure analysis of the obtained title compound is shown in FIG.

¹ H NMR (500 MHz, acetone-d ₆ ): d 9.15 (d, 1H, J (HH) = 7.8 Hz), 9.09 (d, 1H, J (HH) = 9.3 Hz), 8.91 (d, 1H, J (HH) = 1.0 Hz), 8.90 (d, 1H, J (HH) = 7.8 Hz), 8.81 (d, 1H, J (HH) = 9.3 Hz), 8.71 (d, 1H, J (HH) = 8.3 Hz), 8.55 (s, 1H), 8.54 (d, 1H, J (HH) = 6.3 Hz), 8.47 (d, 1H, J (HH) = 5.4 Hz), 8.35 (dt, 1H, J (HH ) = 7.8 and 1.0 Hz), 8.32 (dt, 1H, J (HH) = 7.8 and 1.0 Hz), 8.27 (dt, 1H, J (HH) = 9.3 and 1.0 Hz), 8.23 (dt, 1H, J ( HH) = 9.3 and 1.0 Hz), 8.16 (d, 1H, J (HH) = 8.8 Hz), 8.12 (d, 1H, J (HH) = 4.9 Hz), 8.02 (dt, 1H, J (HH) = 7.8 and 1.0 Hz), 7.99 (d, 1H, J (HH) = 5.4 Hz), 7.93 (dt, 1H, J (HH) = 8.3 and 1.0 Hz), 7.85 (dt, 1H, J (HH) = 7.8 And 1.0 Hz), 7.83 (d, 1H, J (HH) = 5.6 Hz), 7.67 (dt, 1H, J (HH) = 5.4 and 1.0 Hz), 7.59 (t, 1H, J (HH) = 7.3 Hz ), 7.56 (dt, 1H, J (HH) = 5.9 and 1.0 Hz), 7.48 (dt, 1H, J (HH) = 6.3 and 1.0 Hz), 7.42 (dt, 1H, J (HH) = 7.3 and 1.0 Hz), 7.33 (d, 1H, J (HH) = 8.3 Hz).

Example 3 (Preparation of complex 2)
[Ru (pbn) (tpy) (MeCN)] (PF ₆ ) ₂ (complex 2)

Trichloro (2,2 ': 6', 2 "-terpyridyl) ruthenium ([RuCl ₃ (tpy)]) (85 mg, 0.193 mmol) is dissolved in 20 mL of 2-methoxyethanol, and AgPF ₆ (50 mg, 0.198 mmol). 2-methoxyethanol solution (5 mL) was added and stirred for 2 hours at 70 ° C. After the precipitated AgCl was removed by Celite filtration, 6- (2-pyridyl) benzo [b] obtained in Example 1 was used. 1,5-Naphthyridine (50, 0.194 mmol) was added and stirred for 12 hours at 70 ° C. The color of the solution changed from reddish brown to blue, after cooling to room temperature, the solution was concentrated to 1 mL and NH ₄ PF ₆ The precipitated solid ([Ru (pbn) (tpy) Cl] (PF ₆ )]) was collected by filtration and dried, yield 90 mg (60%).

[Ru (pbn) (tpy) Cl] (PF ₆ ) (90 mg, 0.116 mmol) obtained as described above was dissolved in 30 mL of 1,2-dichloroethane and an excess amount of trimethyloxonium tetrafluoroborate. (Me ₃ OBF ₄ ) (200 mg, 1.35 mmol) was added and stirred at 70 ° C. for 2 hours. A green solid precipitated. After removing the solvent, the residue was dissolved in 2-methoxyethanol and poured into aqueous NH ₄ PF ₆ solution. The precipitated solid was collected by filtration and dried. Yield 66 mg ([Ru (pbn) (tpy) (H ₂ O)] (PF ₆ ) ₂ , 64%). Recrystallization from acetonitrile-diethyl ether (MeCN-Et ₂ O) gave the title compound [Ru (pbn) (tpy) (NCMe)] (PF ₆ ) ₂ as blue crystals. The X-ray crystal structure analysis of the obtained title compound is shown in FIG.

¹ H MNR (500MHz, CD ₃ CN): δ10.04 (s, 1H), 9.00 (d, 1H, J (HH) = 8.3 Hz), 8.86 (d, 1H, J (HH) = 9.3 Hz), 8.60 (d, 1H, J (HH) = 8.3 Hz), 8.57 (d, 2H, J (HH) = 7.8 Hz), 8.43 (d, 2H, J (HH) = 7.8 Hz), 8.38 (d, 2H , J (HH) = 7.8 Hz), 8.24 (d, 1H, J (HH) = 8.3 Hz), 8.06 (td, 1H, J (HH) = 7.8 and 1.5 Hz), 7.99 (td, 2H, J ( HH) = 7.8 and 1.5 Hz), 7.92 (t, 1H, J (HH) = 7.8 Hz), 7.77 (t, 1H, J (HH) = 7.8 Hz), 7.67 (d, 2H, J (HH) = 5.4 Hz), 7.50 (d, 1H, J (HH) = 6.3 Hz), 7.24 (td, 2H, J (HH) = 7.8 and 1.5 Hz), 7.21 (t, 1H, J (HH) = 8.8 Hz) , 2.10 (s, 3H).

Example 4 (electrochemical catalytic reduction reaction using complex 1)
Acetone was reduced under the following conditions to obtain isopropyl alcohol. The product was confirmed by GC-MS and GC.
Catalyst: [Ru (pbn) (bpy) ₂ ] (PF ₆ ) ₂ (complex 1)
Solvent: 0.1M acetic acid-sodium acetate buffer / acetone (1: 1 v / v) 10mL + 10mL
Substrate: Acetone (also serves as solvent)
Electrolyte: NaCl 0.1M
Potential: -1.20V
Reaction rate: 2 to 3 times / day Electrolysis cell: FIG.

Example 5 (electrochemical catalytic reduction reaction using complex 1)
Α, α, α-trifluoroacetophenone was reduced under the following conditions to obtain (trifluoromethyl) benzyl alcohol. The product was confirmed by GC-MS.
Catalyst: [Ru (pbn) (bpy) ₂ ] (PF ₆ ) ₂ (complex 1)
Solvent: 0.1 M KH ₂ PO ₄ aqueous solution / dimethylformamide (DMF) (5: 1 v / v) 12 mL (working electrode) + 0.1 M KH ₂ PO ₄ aqueous solution 10 mL (counter electrode)
Substrate: α, α, α-trifluoroacetophenone (CF ₃ COPh)
Electrolyte: KH ₂ PO ₄
Potential: -1.20V
Reaction rate: 2 to 3 times / day Electrolysis cell: FIG.

The conceptual diagram of the catalytic reduction reaction of the organic compound concerning this invention is shown. 2 is an X-ray crystal structure analysis of the catalyst according to the present invention obtained in Example 2. FIG. 3 is an X-ray crystal structure analysis of the catalyst according to the present invention obtained in Example 3. FIG. It is a schematic diagram of the electrolytic cell used in the Example.

Claims (12)

An intermediate for a catalyst capable of electrochemical regeneration represented by the following formula (1a).
[Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁶ and R ⁷ are each independently the same or different and represent a hydrogen atom, a C ₁ -C ₁₀ alkyl group or a C ₆ -C ₁₀ An aryl group. ] The intermediate according to claim 1, wherein R ¹ , R ² , R ³ , R ⁴ , R ⁶ and R ⁷ are hydrogen atoms. A catalyst capable of electrochemical regeneration represented by the following formula (1b).
[Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁶ and R ⁷ are each independently the same or different and represent a hydrogen atom, a C ₁ -C ₁₀ alkyl group or a C ₆ -C ₁₀ an aryl group, R ⁵ is hydrogen atom, M is a monovalent to hexavalent transition metal. ] The catalyst according to claim 3, wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are hydrogen atoms. The catalyst according to claim 3 or 4, wherein M is a metal to which 2,2'-bipyridine can be coordinated. A method for producing a catalyst capable of electrochemical regeneration represented by the following formula (1b),
[Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁶ and R ⁷ are each independently the same or different and represent a hydrogen atom, a C ₁ -C ₁₀ alkyl group or a C ₆ -C ₁₀ an aryl group, R ⁵ is hydrogen atom, M is a monovalent to hexavalent transition metal. ]
In the presence of a base, a pyridine derivative represented by the following formula (2);
[Wherein R ¹ , R ² , R ³ and R ⁴ have the above-mentioned meanings. ]
A quinoline derivative represented by the following formula (3):
[Wherein R ⁶ and R ⁷ have the above-mentioned meanings. ]
The first step of obtaining a reaction product, the second step of coordinating the reaction product obtained in the first step to the transition metal M, the complex obtained in the second step, and the following formula ( 4) with a cation
[Wherein R ⁵ has the above-mentioned meaning. ]
The manufacturing method of a catalyst characterized by including the 3rd process of making this react. The method for producing a catalyst according to claim 6, wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are hydrogen atoms. The method for producing a catalyst according to claim 6 or 7, wherein M is a metal to which 2,2'-bipyridine can be coordinated. A reduction method for reducing an organic compound under electrochemical conditions under acidic conditions in the presence of a catalyst capable of electrochemical regeneration represented by the following formula (1b).
[Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁶ and R ⁷ are each independently the same or different and represent a hydrogen atom, a C ₁ -C ₁₀ alkyl group or a C ₆ -C ₁₀ an aryl group, R ⁵ is hydrogen atom, M is a monovalent to hexavalent transition metal. ] The reduction method according to claim 9, wherein the organic compound has a carbonyl group. The reduction method according to claim 9 or 10, wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are hydrogen atoms. The reduction method according to any one of claims 9 to 11, wherein M is a metal to which 2,2'-bipyridine can be coordinated.