JP2017206474A - Method for hydrogenating unsaturated compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for hydrogenating an unsaturated compound that uses crude gaseous hydrogen having carbon monoxide and carbon dioxide coexist with each other, as a hydrogen source.SOLUTION: A method for hydrogenating an unsaturated compound uses crude gaseous hydrogen as a hydrogen source and is performed in the presence of a frustrated Lewis pair.SELECTED DRAWING: None

Description

  The present invention relates to a method for hydrogenating unsaturated compounds using crude hydrogen gas as a hydrogen source.

  The hydrogenation reaction of an unsaturated compound is a conversion reaction widely used in a process for producing a high-functional material, a pharmaceutical process, and the like. Conventionally, hydrogenation reactions are carried out by catalytic reactions using transition metals as active species, and if impurities such as carbon monoxide and carbon dioxide are present in the reaction system, catalyst deactivation and side reactions will occur. There was a problem. Therefore, as the hydrogen source, expensive high-purity hydrogen from which impurities have been removed must be used. However, most industrial hydrogen gas is produced by steam reforming of natural gas or the like and a water gas shift reaction, and crude hydrogen gas before purification contains carbon monoxide and carbon dioxide.

  On the other hand, a Lewis acid-Lewis base pair called a frustrated Lewis pair (hereinafter referred to as FLP) capable of heterolytically cleaving molecular hydrogen using only organic substances without using metal power is known. It has become. When the Lewis acid and / or Lewis base has a bulky substituent, even if the Lewis acid and the Lewis base coexist, complex formation cannot be performed due to the steric hindrance. The FLP in such a state has both acid and base properties, and thereby can exhibit the cooperative action of both. Recently, it has been known that FLP can be used as a catalyst for promoting a hydrogenation reaction (Patent Documents 1 and 2, Non-Patent Documents 1 and 2). Non-Patent Documents 1 and 2 describe hydrogenation reactions of imines and ketones, but hydrogenation reactions using crude hydrogen gas that may contain impurities such as carbon monoxide and carbon dioxide have not been achieved.

US2010 / 0048949 US2013 / 0018207

Angew. Chem. Int. Ed. 2015, 54, 6400-6441 Chem. Soc. Rev. , 2015, 44, 2202-2220

  As described above, in the conventional hydrogenation reaction using a transition metal catalyst, expensive high-purity hydrogen must be used to suppress the deactivation of the catalyst.

  The present invention has been made paying attention to the above circumstances, and its object is to provide a method using crude hydrogen gas containing carbon monoxide and carbon dioxide as a raw material for the hydrogenation reaction.

The present inventor has made various studies in order to achieve the above object, and arrived at the present invention.
That is, the present invention is a method for hydrogenating unsaturated compounds, which is carried out using crude hydrogen gas as a hydrogen source and in the presence of FLP.
The present invention is also a method for producing a hydrogenated compound, comprising a step of adding a hydrogen atom to at least one unsaturated bond of an unsaturated compound using crude hydrogen gas as a hydrogen source and in the presence of FLP.

  According to the present invention, even when crude hydrogen gas containing carbon monoxide or carbon dioxide is used as a raw material for the hydrogenation reaction, the deactivation of the catalyst is suppressed, and the unsaturated compound is unsaturated in a preferable yield. The bond can be hydrogenated. That is, it is possible to efficiently hydrogenate unsaturated bonds of unsaturated compounds using crude hydrogen gas containing carbon monoxide and carbon dioxide without using high-purity hydrogen. Can be used effectively, and reduction of raw material costs can be expected.

Hereinafter, the present invention will be described in detail.
A combination of two or more preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.

[Hydrogenation method of the present invention]
The hydrogenation method of the present invention is a method for hydrogenating an unsaturated compound in which crude hydrogen gas is used as a hydrogen source and the unsaturated compound is hydrogenated in the presence of FLP.
In the present invention, “FLP” is a Lewis acid-Lewis base pair, and at least one of the acid and base has a bulky structure. The generation method of FLP is not particularly limited. For example, FLP may be obtained by mixing Lewis acid and Lewis base, or by adding pre-complexed Lewis acid and Lewis base to the reaction system and heating. Complexation may be released and FLP may be generated in the reaction system.

  In the present invention, “crude hydrogen gas” refers to hydrocarbons such as natural gas, naphtha, heavy oil, coal, petroleum exhaust gas, shale oil, alcohols such as methanol and ethanol, organic substances such as biomass and industrial waste plastics. It is a mixed gas containing hydrogen produced from a radioactive waste, and contains carbon monoxide and / or carbon dioxide. Crude hydrogen gas produced in a large chemical plant may be used, or one supplied from a small domestic reformer. The crude hydrogen gas preferably has a hydrogen content of 20 mol% or more and less than 99.9 mol%, more preferably 50 mol, with respect to 100 mol% of hydrogen, carbon monoxide, and carbon dioxide in total. % Or more and less than 99.9 mol%, more preferably 70 mol% or more and less than 99.9 mol%.

  In the hydrogenation method of the present invention, as the Lewis acid, a compound represented by the following formula (1) can be used.

(R _{1 to} R ₃ are the same or different and each represents a hydrogen atom or an organic group having 1 to 24 carbon atoms, and the organic group having 1 to 24 carbon atoms may have a substituent. Represents a boron atom or an aluminum atom.)
In the above formula (1), the organic group having 1 to 24 carbon atoms is not particularly limited, but is a chain or cyclic alkyl group, a chain or cyclic alkenyl group, an aryl group, a heteroaryl group, a chain or cyclic alkoxy. Preferred examples include an alkyl group, an alkoxy group, an aryloxy group, an alkylene group, and an arylene group, and these may have a substituent.
Substituents include halogen atoms, hydroxyl groups, alkoxy groups, aryloxy groups, carboxyl groups and salts thereof, alkoxycarbonyl groups, acyloxy groups, aroyloxy groups, amino groups, aminocarbonyl groups, cyano groups, sulfone groups and salts thereof, alkyls Sulfonyl group, alkylsulfanyl group, alkylsulfinyl group, alkylsulfenyl group, arylsulfonyl group, arylsulfanyl group, arylsulfinyl group, arylsulfenyl group, chain or cyclic alkyl group, chain or cyclic alkenyl group, aryl group, Preferred examples include a heteroaryl group, a chain or cyclic dialkylamino group, a chain or cyclic dialkylaminocarbonyl group, a chain or cyclic alkoxyalkyl group, an alkylene group, and an arylene group. Substituents may further have a substituent. Note that “may have a substituent” means that one or more of the hydrogen atoms of the organic group are substituted with a substituent. For example, an alkyl group having a substituent is an alkyl group. Represents an alkyl group having a structure in which one or more of the hydrogen atoms are substituted with a substituent.

When R _{1 to} R ₃ are organic groups and have a substituent, the number of carbons per organic group may be 1 to 24, and two or more substituents may be used even if there are a plurality of substituents. It may have a group. When R _{1 to} R ₃ are organic groups, the number of carbon atoms is preferably 2 or more, more preferably 4 or more, further preferably 6 or more, and preferably 22 or less, 20 The following is more preferable.

  Specific examples of the organic group having 1 to 24 carbon atoms that may have the substituent include an aryl group having 3 to 24 carbon atoms, an alkyl group having 1 to 24 carbon atoms, and a carbon group having 2 to 24 carbon atoms. An alkenyl group, an alkoxy group having 1 to 24 carbon atoms, an arylalkyl group having 7 to 24 carbon atoms, an aryloxy group having 6 to 24 carbon atoms, an arylalkoxy group having 7 to 24 carbon atoms, and an alkylthio group having 1 to 24 carbon atoms , An arylthio group having 6 to 24 carbon atoms, an arylalkylthio group having 7 to 24 carbon atoms, an alkylsulfonyloxy group having 1 to 24 carbon atoms, an arylsulfonyloxy group having 6 to 24 carbon atoms, and an arylalkyl having 7 to 24 carbon atoms A sulfonyloxy group etc. are mentioned.

It is preferable that the C1-C24 organic group which may have the said substituent has an electron withdrawing substituent. Thereby, the Lewis acidity of the Lewis acidic compound portion in the complex of the present invention can be improved, and the performance of the FLP generated from the complex of the present invention as a catalyst can be further enhanced. Examples of the electron withdrawing group include a nitro group, a cyano group, and a halogen atom, and among them, a halogen atom is preferable. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and among them, a fluorine atom and / or a chlorine atom is particularly preferable.
The organic group having 1 to 24 carbon atoms which may have a substituent preferably has a tertiary carbon atom and / or a quaternary carbon atom, and may have an aromatic group. It is more preferably a group, and even more preferably a phenyl group which may have a substituent.

  The organic group having 1 to 24 carbon atoms which may have a substituent is preferably an aromatic group, more preferably an aryl group or a heteroaryl group, a 4-pyridyl group, 2, 3 , 5,6-tetrafluoro-4-pyridyl group, pentafluorophenyl group, 2-fluorophenyl group, 2,3-difluorophenyl group, 2,4-difluorophenyl group, 2,5-difluorophenyl group, 2, 6-difluorophenyl group, 3,5-difluorophenyl group, 2,3,6-trifluorophenyl group, 2,4,6-trifluorophenyl group, 2,3,4,6-tetrafluorophenyl group, 2 , 3,5,6-tetrafluorophenyl group, 2,2 ′, 3,3 ′, 4,4 ′, 5,5 ′, 6-nonafluoro-1,1′-biphenyl group, pentachlorophenyl group, 2 -Chlorophenyl group, 2,3-dichlorophenyl group, 2,4-dichlorophenyl group, 2,5-dichlorophenyl group, 2,6-dichlorophenyl group, 3,5-dichlorophenyl group, 2,3,6-trichlorophenyl group, 2 , 4,6-trichlorophenyl group, 2,3,4,6-tetrachlorophenyl group, 2,3,5,6-tetrachlorophenyl group, 2,4-bis (trifluoromethyl) phenyl group, 2,5- Bis (trifluoromethyl) phenyl group, 2,6-bis (trifluoromethyl) phenyl group, 3,5-bis (trifluoromethyl) phenyl group, 2,4,6-tris (trifluoromethyl) phenyl group, It is more preferably a 2,4,6-trimethylphenyl group, a pentafluorophenyl group, a 2,6-difluorophenyl group, 2,4, -Trifluorophenyl group, 2,3,5,6-tetrafluorophenyl group, 2,2 ', 3,3', 4,4 ', 5,5', 6-nonafluoro-1,1'-biphenyl group , Pentachlorophenyl group, 2,6-dichlorophenyl group, 2,4,6-trichlorophenyl group, 2,6-bis (trifluoromethyl) phenyl group, 3,5-bis (trifluoromethyl) phenyl group, 2, More preferably, it is a 4,6-tris (trifluoromethyl) phenyl group, a pentafluorophenyl group, a 2,6-difluorophenyl group, a 2,4,6-trifluorophenyl group, 2,3,5,6. -Tetrafluorophenyl group, 2,2 ', 3,3', 4,4 ', 5,5', 6-nonafluoro-1,1'-biphenyl group, pentachlorophenyl group, 2,6-dichlorofe Nyl group, 2,4,6-trichlorophenyl group, 2,6-bis (trifluoromethyl) phenyl group, 3,5-bis (trifluoromethyl) phenyl group, 2,4,6-tris (trifluoromethyl) It is particularly preferred that it is a phenyl group.

At least one of R _{1 to} R ₃ is preferably an aromatic group. When at least one of R _{1 to} R ₃ is an aromatic group, the reaction efficiency in the hydrogenation method of the present invention tends to be improved. Two of R _{1 to} R ₃ are more preferably aromatic groups, and three are more preferably aromatic groups.

  In the above formula (1), A represents a boron atom or an aluminum atom, but a boron atom is more preferably a boron atom because the stability of the compound is higher.

  In the hydrogenation method of the present invention, as the Lewis base, a compound represented by the following formula (2) or the following formula (3) can be used.

(R _{4 to} R ₆ are the same or different and each represents a hydrogen atom or an organic group having 1 to 24 carbon atoms, which may be bonded to each other to have a monocyclic structure or a condensed ring structure, The organic group of ˜24 may have a substituent, M ₁ represents an oxygen atom, a nitrogen atom, a phosphorus atom, or a sulfur atom, provided that when M ₁ is an oxygen atom or a sulfur atom, R ₆ is not exist.)

(R < ₄ > -R < ₅ >, R < ₇ > is the same or different, represents a hydrogen atom or a C1-C24 organic group, and this C1-C24 organic group may have a substituent. M ₂ represents an oxygen atom, a nitrogen atom, or a sulfur atom, provided that R ₇ does not exist when M ₂ is an oxygen atom or a sulfur atom.)
The _R 4 to R _6, an organic group of _R 4 _~R 5, _{R 7} may 1 to 24 carbon atoms which may have a substituent in the above formula (3) in the formula (2), the formula ( Examples thereof are the same groups as R _{1 to} R ₃ in 1). Examples of the organic group having 1 to 24 carbon atoms in R ₇ include an alkylsulfonyl group, an arylsulfonyl group, and an aminosulfonyl group. R _{4 to} R ₆ in the above formula (2), R _{4 to} R ₅ and R ₇ in the above formula (3) are a chain or cyclic alkyl group, a chain or cyclic alkenyl group, an aryl group, a heteroaryl group, It is preferably a chain or cyclic alkoxyalkyl group, an alkylene group, or an arylene group.
When R _{4 to} R _{6 in} the above formula (2) and R _{4 to} R ₅ and R ₇ in the above formula (3) are organic groups, the number of carbon atoms is preferably 2 or more, and more preferably 3 or more. More preferably, it is more preferably 4 or more, preferably 20 or less, and more preferably 18 or less.

  In the present invention, the alkyl group having 1 to 24 carbon atoms refers to a linear or molecular chain monovalent aliphatic saturated hydrocarbon group having 1 to 24 carbon atoms. For example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, n-pentyl group, n-hexyl group, n-dodecyl group, n-tridecyl group, n -A tetradecyl group, n-hexadecyl group, n-octadecyl group, n-eicosyl group, etc. can be mentioned. Among these, a C1-C18 alkyl group is preferable and a C1-C10 alkyl group is more preferable.

  The aryl group having 3 to 24 carbon atoms refers to a monovalent aromatic hydrocarbon group having 1 to 24 carbon atoms. Examples thereof include a phenyl group, a naphthyl group, an indenyl group, a biphenyl group, a phenanthrenyl group, an anthracenyl group, a 4-pyridyl group, and a tolyl group. Among these, an aryl group having 5 to 18 carbon atoms is preferable, and an aryl group having 5 to 15 carbon atoms is more preferable.

  An alkylene group having 1 to 24 carbon atoms refers to a linear or molecular chain divalent aliphatic saturated hydrocarbon group having 1 to 24 carbon atoms. For example, methylene group, ethylene group, propylene group, 2,2-propylene group (dimethylmethylene group), butylene group, dimethylethylene group, pentylene group, hexylene group, 2,2-hexylene group (butyl-methylmethylene group), Examples include an octylene group, a decylene group, a dodecylene group, a tetradecylene group, a hexadecylene group, and an eicosylene group. Among these, a C1-C15 alkylene group is preferable and a C1-C10 alkylene group is more preferable.

  A C1-C24 arylene group means a C1-C24 linear or molecular chain bivalent aromatic hydrocarbon group. For example, 1,2-phenylene group, 1,8-naphthalene group, 2,2′-biphenylene group, phenanthrene group and the like can be mentioned. Among these, an arylene group having 6 to 14 carbon atoms is preferable, and an arylene group having 6 to 12 carbon atoms is more preferable.

  An alkenyl group having 1 to 24 carbon atoms refers to a linear or molecular chain divalent aliphatic unsaturated hydrocarbon group having 2 to 24 carbon atoms. For example, a vinyl group, an allyl group, a cyclohexenyl group, etc. can be mentioned. Among these, an alkenyl group having 2 to 15 carbon atoms is preferable, and an alkenyl group having 2 to 10 carbon atoms is more preferable.

  The cycloalkyl group having 3 to 24 carbon atoms means a cyclic monovalent aliphatic saturated hydrocarbon group having 3 to 24 carbon atoms. For example, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a norbornyl group, an adamantyl group, and the like can be given. Among these, a C3-C18 cycloalkyl group is preferable and a C3-C12 cycloalkyl group is more preferable.

  A C1-C24 alkoxy group means a C1-C24 linear or branched monovalent aliphatic saturated hydrocarbon oxy group. Examples thereof include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a t-butoxy group, a pentoxy group, and a hexoxy group. Among these, a C1-C18 alkoxy group is preferable and a C1-C10 alkoxy group is more preferable.

  The aryloxy group having 6 to 24 carbon atoms means a linear or branched monovalent aromatic hydrocarbon oxy group having 6 to 24 carbon atoms. For example, phenoxy group, 1-naphthyloxy group, p-ethylphenoxy group, 3,5-diphenylphenoxy group, 3,5-bis (3 ′, 4′-bis (trifluoromethyl) phenyl) phenoxy group, 4- Examples thereof include an n-octylphenoxy group.

M ₁ in the formula _(2), the M ₂ in the formula (3), since it tends to improve reaction efficiency, an oxygen atom, a nitrogen atom, more preferably a phosphorus atom.

  As will be described later, the Lewis base may be a hydrogenation target (that is, an unsaturated compound in the present invention). When the Lewis base is the unsaturated compound of the present invention, it is more preferably represented by the above formula (3).

  The Lewis acid and the Lewis base may exist in the same molecule or may exist as a complex. That is, as the FLP, a compound having a Lewis acid and a Lewis base in the same molecule or a Lewis acid Lewis base complex may be used.

  The unsaturated compound used in the hydrogenation reaction of the present invention is an imine, a nitrogen-containing heterocyclic compound, an aldehyde, a ketone, an alkene, an alkyne, an oligomer or a polymer having an unsaturated bond, and one or more kinds may be used. it can. Examples of the nitrogen-containing heterocyclic compound include pyridines, quinolines, acridines, 1,10-phenanthrolines, and indoles. The oligomer or polymer having an unsaturated bond may have one or more unsaturated bonds in the same molecule.

  The hydrogenation method of the present invention is usually carried out using a solvent. The solvent that can be used is preferably a solvent that does not react with FLP or does not inhibit the subsequent hydrogenation reaction of the unsaturated compound, and can appropriately dissolve FLP and the unsaturated compound. For example, aromatic hydrocarbon solvents such as toluene; aliphatic hydrocarbon solvents such as n-hexane; ketone solvents such as acetone; alcohol solvents such as methanol; ether solvents such as tetrahydrofuran; ester solvents such as ethyl acetate Nitrile solvents such as acetonitrile; halogenated hydrocarbon solvents such as chloroform; amide solvents such as dimethylformamide; sulfoxide solvents such as dimethyl sulfoxide; lactone solvents such as γ-butyrolactone; carbonate solvents such as ethylene carbonate; , And a mixture of two or more of these can be used. Note that when a Lewis acid, a Lewis base, an unsaturated compound, or the like is dissolved in a solvent in advance, the solvents of these solutions may be the same or different. Moreover, you may implement without using a solvent.

  The hydrogenation reaction of the present invention is preferably carried out by dissolving a Lewis acid, a Lewis base, and an unsaturated compound in a solvent and mixing crude hydrogen gas. The hydrogenation reaction according to the present invention can be carried out while adding crude hydrogen gas. The present invention is also characterized in that the hydrogenation reaction can be carried out under normal pressure or slightly pressurized conditions. Although the said pressure may be a normal pressure, a hydrogenation reaction can be implemented efficiently by performing it in a pressurized state. When the pressure is applied, if the pressure is too large, the energy required for the pressurization becomes large and inefficiency may occur, so 500 atm or less is preferable, 100 atm or less is more preferable, and 50 atm or less is particularly preferable.

[Production method of the present invention]
The method for producing a hydrogenated compound of the present invention comprises adding a hydrogen atom to at least one unsaturated bond of an unsaturated compound (“hydrogenation” using crude hydrogen gas as a hydrogen source and in the presence of a frustrated Lewis pair. Process ”). The above-mentioned “hydrogenated compound” means a compound in which a hydrogen atom is added to at least one unsaturated bond of an unsaturated compound, and is sometimes referred to as “hydrogenated compound”.
When the unsaturated compound includes two or more unsaturated bonds, a hydrogen atom may be added to only one unsaturated bond, or a hydrogen atom may be added to two or more unsaturated bonds. . Therefore, the hydrogenated compound of the present invention may be an unsaturated compound or a saturated compound.

  Examples of the hydrogenated compound of the present invention include amines such as piperidine, indoline, tetrahydroquinoline and tetrahydrophenanthroline; alcohols, alkanes and alkenes.

  A mode and a preferable mode of adding a hydrogen atom to at least one unsaturated bond of the unsaturated compound are as described in the hydrogenation method of the present invention.

  The production method of the present invention essentially includes the hydrogenation step, but may include other steps. For example, a purification process, catalyst deactivation process, dilution process, concentration process, extraction process, unreacted raw material recovery process, filtration process, catalyst recovery process, and the like are exemplified.

  For example, when a hydrogenated compound is insolubilized or crystallized and precipitated, a step of filtering the precipitate may be provided. When the hydrogenated compound is solid, a step of washing with a poor solvent such as n-hexane may be provided. When the hydrogenated compound is solid, a drying step may be provided. The drying step may be performed under reduced pressure. When the hydrogenated compound is a liquid, a step of purification by distillation or the like may be provided.

  When the catalyst is reused, the catalyst can be insolubilized or crystallized to be collected, recovered by a filtration step, and reused in the next reaction.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

<Example 1> Hydrogenation reaction according to the present invention Under a nitrogen atmosphere, Nt-Bu-benzylideneamine (16.1 mg, 0.10 mmol), tris (pentafluorophenyl) borane (5.1 mg, 0.01 mmol) Benzene (0.5 ml) was added to the pressure vessel. Thereafter, the inside of the pressure vessel was replaced with crude hydrogen gas [H ₂ (2.5 atm), CO (3.0 atm)] and heated at 100 ° C. for 1 hour. When the yield was determined from the area ratio of the raw material and the product peak by ¹ H-NMR measurement using this reaction solution, Nt-Bu-benzylamine was quantitatively obtained by the hydrogenation reaction.

Example 2 Hydrogenation Reaction According to the Present Invention Under a nitrogen atmosphere, N-benzylidene-N- (diphenylmethyl) amine (27.1 mg, 0.10 mmol), tris (pentafluorophenyl) borane (5.1 mg, 0 0.01 mmol) and benzene (0.5 ml) were added to a pressure vessel. Thereafter, the pressure vessel crude hydrogen gas _{[H 2 (2.5atm), CO} (1.5atm), CO 2 (1.5atm)] was replaced with and heated for 1 hour under 100 ° C.. Using this reaction solution, the yield was determined from the peak area ratio of the raw material and the product by ¹ H-NMR measurement. As a result, N-benzyl-N- (diphenylmethyl) amine was obtained by a hydrogenation reaction at a yield of 59%. Got in.

Example 3 Hydrogenation Reaction According to the Present Invention Under a nitrogen atmosphere, 2-phenylquinoline (163.9 mg, 0.80 mmol), tris (pentafluorophenyl) borane (20.5 mg, 0.04 mmol), toluene (3 0.0 ml) was added to the pressure vessel. Thereafter, the inside of the pressure vessel was replaced with crude hydrogen gas [H ₂ (2.5 atm), CO (2.5 atm)] and heated at 100 ° C. for 4 hours. Using this reaction solution, the yield was determined from the peak area ratio of the raw material to the product by gas chromatography analysis (FID), and 2-phenyl-1,2,3,4-tetrahydroquinoline was obtained by hydrogenation reaction. Was obtained quantitatively.

Example 4 Hydrogenation Reaction According to the Present Invention Under a nitrogen atmosphere, 1,10-phenanthroline (145.0 mg, 0.80 mmol), tris (pentafluorophenyl) borane (20.5 mg, 0.04 mmol), toluene ( 3.0 ml) was added to the pressure vessel. Thereafter, the inside of the pressure vessel was replaced with crude hydrogen gas [H ₂ (2.5 atm), CO (2.5 atm)] and heated at 100 ° C. for 3 hours. Purification was performed by column chromatography (hexane / ethyl acetate = 9/1), and the isolated yield was determined. As a result of the hydrogenation reaction, 1,2,3,4-tetrahydro-1,10-phenanthroline was obtained at a yield of 89. %.

<Example 5> Hydrogenation reaction according to the present invention Under a nitrogen atmosphere, 1,2-dimethylindole (58.7, 0.80 mmol), tris (pentafluorophenyl) borane (20.5 mg, 0.04 mmol), toluene (3.0 ml) was added to the pressure vessel. Thereafter, the inside of the pressure vessel was replaced with crude hydrogen gas [H ₂ (2.5 atm), CO (2.5 atm)] and heated at 80 ° C. for 18 hours. Using this reaction solution, the yield was determined from the peak area ratio of the raw material to the product by gas chromatography analysis (FID). As a result, 1,2-dimethylindoline was obtained in a yield of 33% by the hydrogenation reaction. .

As shown in Table 1, it has been clarified that the hydrogenation method of the present invention can efficiently hydrogenate unsaturated compounds with a good yield using crude hydrogen gas as a hydrogen source.

Claims (10)

A method for hydrogenating unsaturated compounds, using crude hydrogen gas as a hydrogen source and in the presence of a frustrated Lewis pair. A method for producing a hydrogenated compound, comprising a step of adding a hydrogen atom to at least one unsaturated bond of an unsaturated compound using crude hydrogen gas as a hydrogen source in the presence of a frustrated Lewis pair. The manufacturing method of Claim 2 whose Lewis acid is a compound represented by following formula (1).

(R _{1 to} R ₃ are the same or different and each represents a hydrogen atom or an organic group having 1 to 24 carbon atoms, and the organic group having 1 to 24 carbon atoms may have a substituent. Represents a boron atom or an aluminum atom.) The manufacturing method of Claim 2 or 3 whose Lewis base is a compound represented by following formula (2).

(R _{4 to} R ₆ are the same or different and each represents a hydrogen atom or an organic group having 1 to 24 carbon atoms, which may be bonded to each other to have a monocyclic structure or a condensed ring structure, To 24 may have a substituent, M represents an oxygen atom, a nitrogen atom, a phosphorus atom, or a sulfur atom, provided that when M ₁ is an oxygen atom or a sulfur atom, R ₆ is present. do not do.) The manufacturing method in any one of Claim 2 or 3 whose Lewis base is a compound represented by following formula (3).

(R < ₄ > -R < ₅ >, R < ₇ > is the same or different, represents a hydrogen atom or a C1-C24 organic group, and this C1-C24 organic group may have a substituent. M represents an oxygen atom, a nitrogen atom, or a sulfur atom, provided that when M ₂ is an oxygen atom or a sulfur atom, R ₇ does not exist.) The production method according to claim 2, wherein the reaction is carried out in the presence of a frustrated Lewis pair having a Lewis acid and a Lewis base in the same molecule. The production method according to claim 6, wherein the Lewis acid is a boron compound. The production method according to claim 2, wherein the Lewis acid is tris (pentafluorophenyl) borane. 9. The production method according to claim 2, wherein crude hydrogen gas containing 0.1% or more of carbon monoxide and carbon dioxide is used. The unsaturated compound is one kind or two or more kinds selected from imine, nitrogen-containing heterocyclic compound, aldehyde, ketone, alkene, alkyne, oligomer or polymer having an unsaturated bond. The manufacturing method as described.