JP2003300930A - Method for producing ester compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an ester compound in a short time and in a good efficiency without requiring an additive such as oxygen or a hydrogen receptor, etc., and also without being restricted by equilibrium. <P>SOLUTION: This method for producing the ester compound by dehydrogenating a mixture consisting of an aldehyde and an alcohol in a liquid phase is characterized by using an 8th group transition metal catalyst having at least 1 ligand selected from (i) a single position phosphine ligand having 1 alkyl group and 2 aryl groups as substituents, (ii) a single position phosphine ligand having 2 alkyl groups and 1 aryl group as substituents and (iii) a phosphine ligand with 2 positions formed by bonding phosphorus atoms at both ends of an alkyl chain and expressed by following formula (1). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an ester compound, and more particularly to a method for producing an ester compound by dehydrogenating a mixture of aldehydes and alcohols in a liquid phase.

[0002]

2. Description of the Related Art A method for producing an ester compound for dehydrogenating a mixture of aldehydes and alcohols using a heterogeneous catalyst is disclosed in, for example, JP-A 2000-302727. Reactions using catalysts have been reported. However, there is a risk of explosion due to addition of molecular oxygen, and it cannot be said that the safety problem in industrial practicality has been solved. Further, there is a problem that the generated hydrogen gas cannot be reused. Further, JP 2001-328966 A reports a method for producing an ester by dehydrogenation of a mixture of an aldehyde and an alcohol using a heterogeneous catalyst, which does not require molecular oxygen, but is a gas phase method. Therefore, hydrogen gas by-produced by the reaction and the ester compound as a product coexist with the catalyst in a homogeneous phase. Therefore, equilibrium restriction is caused by the reverse hydrogenation reaction of the ester, and it is difficult to achieve high conversion and high selectivity. Therefore, at present, the development of a liquid-phase dehydrogenation reaction that can release the generated hydrogen gas from the reaction system is expected.

On the other hand, a method for producing an ester compound which uses a complex catalyst to dehydrogenate a mixture of aldehydes and alcohols in a liquid phase has already been studied. For example, a reaction using a ruthenium complex catalyst having triphenylphosphine as a ligand can be mentioned (J. Org. Chem., 198).
7, 52, 4319-4327). However, this catalyst system requires a long time for the reaction to proceed, and there remains a problem of productivity such as improvement of reaction rate for industrial use.

[0004]

DISCLOSURE OF THE INVENTION The present invention uses a transition metal complex catalyst, does not require additives such as oxygen and hydrogen acceptors, and has an equilibrium constraint to efficiently produce an ester compound in a short time. It is an object to provide a manufacturing method.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that (i) a monodentate phosphine ligand having one alkyl group and two aryl groups as substituents, (ii) ) A monodentate phosphine ligand having two alkyl groups and one aryl group as a substituent, and (iii) a specific bidentate phosphine ligand having a phosphorus atom bonded to both ends of an alkyl chain. It was found that the above-mentioned problems can be solved by using at least one ligand, especially, the complex catalyst having the bidentate phosphine ligand of (iii), and completed the present invention. That is, the gist of the present invention is from (1) to
It exists in (4). (1) In the method for producing an ester compound by dehydrogenating a mixture of aldehydes and alcohols in a liquid phase, (i) monodentate phosphine coordination having one alkyl group and two aryl groups as substituents Child, (ii) a monodentate phosphine ligand having two alkyl groups and one aryl group as substituents, and (iii) a bidentate phosphine having a phosphorus atom bonded to both ends of an alkyl chain represented by the following structural formula. At least one selected from the group consisting of ligands
A method for producing an ester compound, which comprises using a Group 8 transition metal complex catalyst having one ligand.

[0006]

[Chemical 2]

(In the formula, A, B, C and D represent an aryl group or an alkyl group, provided that at least one of A and B and at least one of C and D is an aryl group. Y is alkyl. Represents a chain.)

(2) The production method according to (1) above, wherein the Group 8 transition metal complex catalyst is a ruthenium complex catalyst.

(3) The mixing ratio of aldehydes and alcohols is 1 in terms of molar ratio of aldehydes to alcohol.
The manufacturing method as described in said (1) or (2) which is -4. (4) The production method according to any of (1) to (3) above, wherein the aldehydes and the alcohols have the same carbon skeleton.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a method for producing an ester compound by dehydrogenating a mixture of aldehydes and alcohols, wherein "(i) one alkyl group and 2
A monodentate phosphine ligand having one aryl group as a substituent, (ii) a monodentate phosphine ligand having two alkyl groups and one aryl group as a substituent, and (ii)
i) Group 8 transition metal complex catalyst having at least one ligand selected from the group consisting of bidentate phosphine ligands having phosphorus atoms bonded to both ends of the alkyl chain represented by the above structural formula ”(hereinafter , Which may be collectively referred to as a Group 8 transition metal complex catalyst having a phosphine ligand). The details will be described below.

In the present invention, the aldehydes and alcohols used as the raw materials specifically have 1 to 1 carbon atoms.
50 saturated or unsaturated aldehydes and alcohols are mentioned, and aldehydes and alcohols having 1 to 10 carbon atoms are particularly preferable. Further, these aldehydes and alcohols may have other substituents.

Specific examples of aldehydes include formaldehyde, ethanal, propanal, butanal, pentanal, hexanal, heptanal, octanal, nonanal, decanal, acrolein, and crotonaldehyde, even if they have a functional group. Include aliphatic aldehydes, benzaldehyde, cinnamylaldehyde, or aromatic aldehydes that may have a functional group such as a methoxy group, a halogen group or a hydrocarbon group on the aromatic ring. Can be mentioned. Aldehydes having a boiling point of 100 ° C. or higher, which are easy to react at high temperature under atmospheric pressure, are preferable from the viewpoint of reaction rate, and particularly preferably, aldehydes having a boiling point of 150 ° C. or higher.

Specific examples of alcohols include methanol, ethanol, 1-propanol, 2-propanol 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol and 1-hexanol. , 2-hexanol, 3-hexanol, 1-
Heptanol, 2-heptanol, 3-heptanol,
4-heptanol, 1-octanol, 2-octanol, 3-octanol, 4-octanol, 1-nonanol, 2-nonanol, 3-nonanol, 4-nonanol, 5-nonanol, 1-decanol, 2-decanol, 3- Decanol, 4-decanol, 5-decanol, allyl alcohol, 1-butenol, 2-butenol, 1-pentenol, 2-pentenol, 1-hexenol, 2-hexenol, 3-hexenol, 1-heptenol, 2-heptenol. , 3-heptenol, 1
-Octenol, 2-octenol, 3-octenol, 4-octenol, 1-nonenol, 2-nonenol, 3-nonenol, 4-nonenol, 1-decenol, 2-decenol, 3-decenol, 4-decenol, 5-decenol , Cyclohexanol, cyclopentanol, cycloheptanol, 1-phenethyl alcohol, 2-phenethyl alcohol, methanolamine,
Ethanolamine, and in particular, polyols in which any two hydroxyl groups contained in the molecule are linked by a carbon chain of 3 to 6, specifically 1,3-propanediol,
1,4-butanediol, 1,5-hexanediol,
1,6-hexanediol, 1,2-cyclohexyl dimethylol, 1,3-cyclohexyl dimethylol, 1
-Hydroxymethyl-2-hydroxyethylcyclohexane, 1-hydroxy-2-hydroxypropylcyclohexane, 1-hydroxyl-2-hydroxyethylcyclohexane, 1,2-benzyldimethylol, 1,3
-Benzyl dimethylol, 1-hydroxymethyl-2-
Examples thereof include hydroxyethylbenzene, 1-hydroxy-2-hydroxypropylbenzene, 1-hydroxyl-2-hydroxyethylbenzene and the like. Alcohols having a boiling point of 100 ° C. or higher, which are easy to react at a high temperature under atmospheric pressure, are preferable from the viewpoint of reaction rate, and particularly preferably have a boiling point of 15
Alcohols above 0 ° C.

In the present invention, it is preferable to select aldehydes and alcohols having the same carbon skeleton from the viewpoint of reaction selectivity. Specifically, benzaldehyde and benzyl alcohol, formaldehyde and methanol, ethanal and ethanol, propanal and 1-propanol, butanal and 1-butanol, heptanal and 1-heptanol, hexanal and 1-hexanol, octanal and 1-octanol, decanal. And 1-decanol are preferred, and benzaldehyde and benzyl alcohol, octanal and 1-octanol, and decanal and 1-decanol are particularly preferred. For example, in the combination of benzaldehyde and benzyl alcohol,
This is because, when the dehydrogenation reaction proceeds, even if the aldehydes are hydrogenated, the alcohol produced is benzyl alcohol, which is the raw material, and the reaction can be continued without lowering the selectivity.

The mixing ratio of aldehydes and alcohols is usually 1 in terms of the molar ratio of aldehydes to alcohols.
10 to 10, preferably 1 to 4. If the proportion of aldehyde is too high, the amount of hydrogen necessary for producing the ester cannot be secured by dehydrogenation, and a large amount of the raw material aldehyde remains, while if the proportion of aldehyde is too low, stable acetals are formed. However, the reaction rate tends to decrease.

The catalyst of the present invention comprises (i) a monodentate phosphine ligand having one alkyl group and two aryl groups as substituents, and (ii) a monodentate phosphine ligand having two alkyl groups and one aryl group as substituents. A phosphine ligand,
And (iii) a Group 8 transition metal complex having at least one ligand selected from the group consisting of bidentate phosphine ligands having phosphorus atoms bonded to both ends of the alkyl chain represented by the above structural formula. . Particularly preferably, 2 of (iii)
It is a Group 8 transition metal complex having a bidentate phosphine ligand. The alkyl group as the substituent of phosphine may be linear, branched or cyclic, and usually has 1 to 20 carbon atoms.
And preferably an alkyl group having 1 to 10 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, a decyl group, a benzyl group and a cyclohexyl group. The aryl group as a substituent of phosphine is usually an aryl group having 6 to 24 carbon atoms, preferably 6 to 12 carbon atoms, for example, phenyl,
Examples thereof include naphthyl, tolyl, xylyl and the like.

The bidentate ligand is represented by the following structural formula, in which A, B, C and D represent an aryl group or an alkyl group, provided that at least one of A and B, and , C and D are at least one aryl group.

[0018]

[Chemical 3]

That is, both A and B are aryl groups (which may be the same or different), or one is an aryl group and the other is an alkyl group. The same structure is used for C and D. Y represents an alkyl chain, and usually has 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, and most preferably 2. The alkyl chain may have a substituent or may be branched.

An alkyl group as a substituent of these phosphines,
The alkyl chain and the aryl group may further have a substituent, for example, a halogen atom (chlorine, bromine, fluorine, etc.), an amino group, an alkoxyl group (preferably having 1 carbon atom).
-10), a hydroxyl group, and the like.

(I) Specific examples of the monodentate phosphine ligand having one alkyl group and two aryl groups as substituents include diphenylmethylphosphine, diphenylethylphosphine, diphenylpropylphosphine, diphenylbutylphosphine and diphenyl. Hexylphosphine, diphenyloctylphosphine, diphenylbenzylphosphine, ditolylmethylphosphine, ditolylethylphosphine, ditolylbutylphosphine,
Di (fluorophenyl) methylphosphine, di (chlorophenyl) methylphosphine, di (bromophenyl) methylphosphine, dixylylmethylphosphine, di (methoxyphenyl) methylphosphine, di (hydroxyphenyl) methylphosphine, di (aminophenyl) methyl Examples thereof include phosphine, dinaphthylmethylphosphine and phenyltolylmethylphosphine.

(Ii) Specific examples of the monodentate phosphine ligand having two alkyl groups and one aryl group as substituents include dimethylphenylphosphine, diethylphenylphosphine, dipropylphenylphosphine, dibutylphenylphosphine, Dipentylphenylphosphine, dihexylphenylphosphine, dioctylphenylphosphine, dibenzylphenylphosphine, dimethyltolylphosphine, diethyltolylphosphine, dibutyltolylphosphine, dioctylrylphosphine, dimethyl (fluorophenyl) phosphine,
Examples include dimethyl (chlorophenyl) phosphine, dimethyl (bromophenyl) phosphine, dimethylxylylphosphine, dimethyl (methoxyphenyl) phosphine, dimethyl (hydroxyphenyl) phosphine, dimethyl (aminophenyl) phosphine, dimethylnaphthylphosphine, and methylethylphenylphosphine. To be

(Iii) Specific bidentate phosphine ligands having a phosphorus atom bonded to both ends of an alkyl chain include bis (diphenylphosphino) methane, 1,2
-Bis (diphenylphosphino) ethane, 1,3-bis (diphenylphosphino) propane, 1,2-bis (diphenylphosphino) propane, 1,4-bis (diphenylphosphino) butane, 1,1'- Bis (diphenylphosphino) ferrocene, 1,2-bis (ditolylphosphino) ethane, 1,2-bis (difluorophenylphosphino) ethane, 1,2-bis (dichlorophenylphosphino) ethane, 1,2- Bis (dibromophenylphosphino) ethane, 1,2-bis (dinaphthylphosphino) ethane, 1,2-bis (dimethoxyphenylphosphino) ethane, 1,2-bis (dihydroxyphenylphosphino) ethane, 1, 2-bis (diaminophenylphosphino) ethane, 1,2-bis (methylphenylphosphino) ethane, 1 , 2-bis (ethylphenylphosphino) ethane, 1,2-bis (butylphenylphosphino) ethane, 1,2-bis (cyclohexylphenylphosphino) ethane, bis (methylphenylphosphino)
Examples thereof include methane and 1,3- (methylphenylphosphino) propane, and among them, 1,2-bis (diphenylphosphino) ethane is preferable.

The supply form of the Group 8 transition metal in the present invention is not particularly limited, and the Group 8 transition metal or 8
It is possible to use any of the group transition metal compounds as a source. Examples of the Group 8 transition metal include ruthenium, iridium, and rhodium, with ruthenium being preferred. The Group 8 transition metal compound is preferably a ruthenium compound, and examples thereof include oxides, hydroxides, inorganic acid salts, organic acid salts and complex compounds.

Specific examples of the Group 8 transition metal compound include ruthenium dioxide, ruthenium tetraoxide, ruthenium hydroxide, ruthenium trichloride, ruthenium tribromide, ruthenium triiodide, ruthenium nitrate, ruthenium acetate, tris (acetylacetonato). ) Ruthenium, tris (hexafluoroacetylacetonato) ruthenium, tris (2,2,2
6,6-Tetramethyl-3,5-heptanedionato) ruthenium, sodium hexachlororuthenate, dipotassium tetracarbonylruthenate, pentacarbonylruthenium, cyclopentadienyldicarbonylruthenium, dibromotricarbonylruthenium, chlorotris (triphenylphosphine) hydrido ruthenium,
Tetra (triphenylphosphine) dihydridoruthenium, tetra (trimethylphosphine) dihydridoruthenium, bis (tri-n-butylphosphine) tricarbonylruthenium, tetrahydridodecacarbonyltetraruthenium, dodecacarbonyltriruthenium, octadecacarbonylhexaruthenate Dicecium, undecacarbonylhydrido tetraphenylphosphonium trirutheniumate, iridium trichloride, iridium tribromide, iridium triiodide, iridium nitrate, iridium acetate, tris (acetylacetonato) iridium, tris (hexafluoroacetylacetonato) ) Iridium, rhodium trichloride, rhodium tribromide, rhodium triiodide, rhodium nitrate, rhodium acetate, tris (acetylacetonato) rhodium, tris Hexafluoro acetylacetonate) rhodium, and the like, preferably tris (acetylacetonato) ruthenium, tris (hexafluoroacetylacetonato) ruthenium.

The Group 8 transition metal complex catalyst having a phosphine ligand, which is used in the method of the present invention, may be synthesized in advance, isolated and purified before use. It may be used without purification), or its precursor may be added to the reaction system (ie, aldehydes and alcohols as raw materials) independently to prepare a catalyst in the reaction system for use. Good. When the catalyst is synthesized in advance, it is possible to efficiently generate the catalyst by using the phosphorus compound in excess of the Group 8 transition metal. That is, specifically, in the present invention, as the esterification method, for example, the following methods (1) to (3) can be adopted. (1) A method of separately supplying a Group 8 transition metal and a phosphorus compound into an esterification reaction solution, and performing an esterification reaction while forming a Group 8 transition metal-phosphorus complex catalyst in the reaction solution. (2) Group 8 transition metal-phosphorus compound is pre-reacted to prepare a Group 8 transition metal-phosphorus complex catalyst, and the Group 8 transition metal-phosphorus complex catalyst is isolated and purified, and then fed into the esterification reaction liquid. A method of performing an esterification reaction. (3) A method of performing the esterification reaction by directly supplying the Group 8 transition metal-phosphorus complex catalyst prepared in the same manner as in (2) above into the esterification reaction liquid without isolation and purification.

However, the group 8 transition metal compound, which is the catalyst source, and an alcohol may cause a side reaction to cause a decrease in the selectivity of the esters. Therefore, the catalyst is synthesized in advance, and then the alcohols and the aldehydes are used. The method (2) or (3) is preferably added to the mixture consisting of The method (3) above is simpler than the method (2) above, but depending on the amount of phosphorus to be added, there are phosphorus compounds that are not bonded to the Group 8 transition metal compound,
Since the phosphorus may cause a side reaction with the ester, the method (2) is preferable in that sense.

The case where the esterification is carried out by the above method (1), which is a preferred ruthenium complex catalyst as the Group 8 transition metal complex catalyst in the present invention, will be described in detail. When the ligand is a monodentate phosphine ligand, in the ruthenium complex catalyst, the monodentate phosphine ligand and the ruthenium compound preferably have an atomic ratio of phosphorus atom / ruthenium atom of 1 to 20, Preferably 2
Mixed to be ~ 6. If there are too few phosphine ligands, the reaction rate tends to be low due to insufficient formation of catalytically active species. Conversely, if there are too many phosphine ligands, in the case of monodentate phosphine ligands, Excessive phosphine ligands tend to react with the product ester, producing large amounts of high boiling by-products, leading to poor selectivity.

When the ligand is a bidentate phosphine ligand, in the ruthenium complex catalyst, the bidentate phosphine ligand and the ruthenium compound have a molar ratio of phosphorus atom / ruthenium atom of 2 to It is preferably 4 and more preferably 2-3. When the amount of the phosphine ligand is too small, the catalytically active species are insufficient to be generated and the reaction rate tends to decrease. On the other hand, if the amount is too large, in the case of a bidentate phosphine ligand, an excessive amount of the phosphine ligand blocks the active site of the ruthenium complex catalyst, and the reaction rate tends to decrease.

In the present invention, when a previously prepared Group 8 transition metal complex catalyst is used, that is, when esterification is carried out by the above method (2), the Group 8 transition metal complex catalyst is used as the Group 8 transition metal catalyst in the present invention. In the case of a preferred ruthenium complex catalyst, when the ligand is monodentate, the phosphorus atom and the ruthenium atom contained in the catalyst preferably have a molar ratio of 2 to 4, and particularly preferably 2. Also when the ligand is bidentate, the atomic ratio of phosphorus atom / ruthenium atom is preferably 2 to 4, and particularly preferably 2 in terms of molar ratio.

Further, when the esterification is carried out by the above method (3) and the ruthenium complex catalyst is preferable as the Group 8 transition metal complex catalyst in the present invention, it is prepared in advance in the complex catalyst preparation liquid. When the ligand is monodentate, the phosphorus atom and the ruthenium atom contained in are in a molar ratio of 2 to
It is preferably 6, and when the ligand is bidentate, the molar ratio is preferably 2 to 3.

(I) Specific examples of the Group 8 transition metal complex having a monodentate phosphine ligand having one alkyl group and two aryl groups as substituents include bis (acetylacetonato) bis (diphenylmethyl). Phosphine) ruthenium, bis (acetylacetonato) bis (diphenylethylphosphine) ruthenium, bis (acetylacetonato) bis (diphenylbutylphosphine) ruthenium, bis (acetylacetonato) bis (diphenyloctylphosphine) ruthenium, bis (acetylacetoacetate) Nato) bis (dinaphthylmethylphosphine) ruthenium,
Dihydrido tetrakis (diphenylmethylphosphine)
Ruthenium, dihydridotetrakis (diphenylethylphosphine) ruthenium, dihydridotetrakis (diphenylbutylphosphine) ruthenium, dihydridotetrakis (diphenyloctylphosphine) ruthenium,
Dihydrido tetrakis (dinaphthylmethylphosphine)
Examples thereof include ruthenium and bis (acetylacetonato) (bis (diphenylphosphino) methane) ruthenium.

Further, (ii) the Group 8 transition metal complex having a monodentate phosphine ligand having two alkyl groups and one aryl group as a substituent is specifically bis (acetylacetonato) bis (dimethyl). Phenylphosphine) ruthenium, bis (acetylacetonato) bis (diethylphenylphosphine) ruthenium, bis (acetylacetonato) bis (dibutylphenylphosphine) ruthenium, bis (acetylacetonato) bis (dioctylphenylphosphine) ruthenium, bis (acetyl) Acetonato) bis (dimethylnaphthylphosphine)
Ruthenium, dihydridotetrakis (dimethylphenylphosphine) ruthenium, dihydridotetrakis (diethylphenylphosphine) ruthenium, dihydridotetrakis (dibutylphenylphosphine) ruthenium, dihydridotetrakis (dioctylphenylphosphine)
Examples thereof include ruthenium and dihydridotetrakis (dimethylnaphthylphosphine) ruthenium.

(Iii) Specific examples of the Group 8 transition metal complex having a specific bidentate phosphine ligand having a phosphorus atom bonded to both ends of an alkyl chain include bis (acetylacetonato) (1,2- Bis (diphenylphosphino) ethane) ruthenium, bis (acetylacetonato) (1,3
-Bis (diphenylphosphino) propane) ruthenium, bis (acetylacetonato) (1,4-bis (diphenylphosphino) butane) ruthenium, dihydride (bis (diphenylphosphino) methane) ruthenium,
Examples include dihydrido (1,2-bis (diphenylphosphino) ethane) ruthenium, dihydrido (1,3-bis (diphenylphosphino) propane) ruthenium, dihydride (1,4-bis (diphenylphosphino) butane) ruthenium, and the like. To be

Preferably, bis (acetylacetonato) bis (dimethylphenylphosphine) ruthenium, bis (acetylacetonato) bis (diethylphenylphosphine) ruthenium, bis (acetylacetonato) bis (dibutylphenylphosphine) ruthenium, bis (acetyl) Acetonato) bis (dioctylphenylphosphine) ruthenium, bis (acetylacetonato) bis (dimethylnaphthylphosphine) ruthenium, bis (acetylacetonato) bis (diphenylmethylphosphine) ruthenium, bis (acetylacetonato) bis (diphenylethylphosphine) ) Ruthenium, bis (acetylacetonato) bis (diphenylbutylphosphine) ruthenium, bis (acetylacetonato) bis (diphenyloctylphosphine) ruthe Um, bis (acetylacetonato) bis (dinaphthyl methyl phosphine) ruthenium,
Dihydrido tetrakis (dimethylphenylphosphine)
Ruthenium, dihydridotetrakis (diethylphenylphosphine) ruthenium, dihydridotetrakis (dibutylphenylphosphine) ruthenium, dihydridotetrakis (dioctylphenylphosphine) ruthenium,
Dihydrido tetrakis (dimethylnaphthylphosphine)
Ruthenium, dihydridotetrakis (diphenylmethylphosphine) ruthenium, dihydridotetrakis (diphenylethylphosphine) ruthenium, dihydridotetrakis (diphenylbutylphosphine) ruthenium, dihydridotetrakis (diphenyloctylphosphine)
Ruthenium, dihydridotetrakis (dinaphthylmethylphosphine) ruthenium, bis (acetylacetonato)
(Bis (diphenylphosphino) methane) ruthenium,
Bis (acetylacetonato) (1,2-bis (diphenylphosphino) ethane) ruthenium, bis (acetylacetonato) (1,3-bis (diphenylphosphino) propane) ruthenium, bis (acetylacetonato)
(1,4-bis (diphenylphosphino) butane) ruthenium.

Particularly preferably, bis (acetylacetonato) (1,2-bis (diphenylphosphino) ethane)
Although it is ruthenium, dihydrido (1,2-bis (diphenylphosphino) ethane) ruthenium is also preferred.

The method of synthesizing a Group 8 transition metal complex catalyst having a phosphine ligand used in the method of the present invention is not limited, but for example, Group 8 transition metal and / or Group 8 transition Examples of the method include heating the metal compound and the phosphine ligand in a gas atmosphere of hydrogen, a rare gas, nitrogen, carbon dioxide, a hydrocarbon gas, or the like, in a solvent or in the absence of a solvent. The heating temperature is usually 120 ° C. or higher, preferably 140 ° C. or higher, and usually 220 ° C. or lower, preferably 200 ° C. or lower.

The amount of these transition metals and / or transition metal compounds used is such that the concentration in the reaction solution is preferably 0.001 to 10.0% by weight, more preferably 0.01 to 10.0% by weight as the metal in the reaction solution. The amount is 3.0% by weight. The reaction liquid contains aldehydes and alcohols as raw materials, and other solvent used as necessary. In the present invention, (i) a Group 8 transition metal complex having a phosphine ligand having one alkyl group and two aryl groups as substituents may be used alone or in combination. (Ii) 8 having a phosphine ligand having two alkyl groups and one aryl group as substituents
Group transition metal complexes may be used alone or in combination of two or more kinds, and (iii) is composed of a bidentate phosphine ligand having a phosphorus atom bonded to both ends of the alkyl chain represented by the above structural formula. The Group 8 transition metal complex having at least one ligand selected from the group may be used alone or in combination of two or more kinds, and the catalyst of (i), (ii) or (iii) is appropriately used. They may be used in combination, but when they are used in combination, they are added so that the catalyst metal concentration is within the above range.

The ester compound produced by the present invention includes butyl butyrate, ethyl butyrate, butyl acetate, ethyl acetate, propyl propionate, pentyl pentanoate, hexyl hexanoate, heptyl heptanoate, octyl octanoate, nonyl nonanoate. Decyl decanoate, benzyl benzoate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, 2-methoxyethyl acrylate, cyclohexyl acrylate, acrylic acid Nonyl, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate,
Examples thereof include 2- (diethylamino) ethyl methacrylate and 2- (dimethylamino) ethyl methacrylate, and preferably ester compounds having a target skeleton, such as benzyl benzoate and octyl octylate.

The method for producing an ester compound of the present invention is carried out in a liquid phase, and a solvent other than the reaction raw material may be further used, or the reaction raw material and the product itself may be used as a solvent and another solvent may be used. You may go without using it. In particular, a method in which the latter reaction raw material and product itself are used as a solvent and no other solvent is used is preferable.

The solvent usable in the present invention includes
For example, diethyl ether, anisole, tetrahydrofuran, ethylene glycol dimethyl ether, ethers of dioxane, aromatic carbon such as benzene, toluene, ethylbenzene and tetralin, aliphatic hydrocarbon such as n-hexane, n-octane and cyclohexane, nitromethane and nitrobenzene. Nitro compounds such as N, N-dimethylformamide, N, N-dimethylacetamide, N
-Carboxylic acid amides such as methylpyrrolidone, hexamethylphosphoric triamide and other amides, ureas such as N, N-dimethylimidazolidinone, sulfones such as dimethyl sulfone, sulfoxides such as dimethyl sulfoxide, gamma butyrolactone , Lactones such as caprolactone, tetraglyme, polyethers such as triglyme, dimethyl carbonate, carbonic acid esters such as ethylene carbonate, and the like, preferably ethers, polyethers, and reaction raw materials, alcohol of the product, They are polyhydric alcohols, aldehydes and esters. Among them, ethers and polyethers are preferable,
Particularly, triglyme and tetraglyme are preferable.

The reaction temperature is usually 20 to 350 ° C, preferably 50 to 250 ° C, more preferably 100 to 220 ° C.
Is. The present invention is an open system, and the reaction can be promoted by extracting hydrogen generated in the reaction, but the reaction proceeds even under normal pressure or under pressure, and hydrogen and hydrocarbon gas such as methane, ethane, butane, etc. , And nitrogen,
It can be carried out under an atmosphere of an inert gas such as argon, helium or carbon dioxide. It is preferably under normal pressure, an inert gas atmosphere, or a hydrogen gas atmosphere. still,
In a hydrogen gas atmosphere, the pressure is 0.
It is preferably 001 MPa to 1 MPa. The reaction can be carried out in either a batch system or a continuous system.

[0043]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples. In the following Examples and Comparative Examples, the selectivity and the conversion were analyzed by gas chromatography using the sampled reaction solutions, and the internal standard method was used to determine the yield of benzyl benzoate and the like, and the raw materials such as benzaldehyde and benzyl alcohol. The remaining amount of was determined and calculated from this value.

Example 1 In a 50 ml glass reactor, 0.375 g of tris (acetylacetonato) ruthenium and 0.374 g of 1,2-bis (diphenylphosphino) ethane (molar ratio, phosphorus / ruthenium = 2. 0), benzaldehyde 4.02
g, 1.01 g of benzyl alcohol (molar ratio, aldehyde / alcohol = 4.1) was added (ruthenium catalyst concentration: 1.6% by weight), and the mixture was reacted at 170 ° C. for 10 hours to give benzyl benzoate having a selectivity of 79%, an aldehyde, Obtained at a total conversion of alcohol of 93%.

Example 2 In a 50 ml glass reactor, 0.298 g of tris (acetylacetonato) ruthenium and 0.301 g of 1,2-bis (diphenylphosphino) ethane (molar ratio, phosphorus / ruthenium = 2. 0), benzaldehyde 2.02
g, 2.02 g of benzyl alcohol (molar ratio, aldehyde / alcohol = 1.0) was added (ruthenium catalyst concentration: 1.6 wt%), and the reaction was carried out at 170 ° C. for 10 hours to select benzyl benzoate with a selectivity of 87%, an aldehyde, Obtained at a total alcohol conversion of 78%.

Example 3 In a 50 ml glass reactor, 0.301 g of tris (acetylacetonato) ruthenium and 0.259 g of diethylphenylphosphine (molar ratio, phosphorus / ruthenium =
2.0), benzaldehyde 2.04 g, benzyl alcohol 2.06 g (molar ratio, aldehyde / alcohol =
1.0) (ruthenium catalyst concentration 1.6% by weight),
The reaction was carried out at 170 ° C. for 10 hours, the selectivity of benzyl benzoate was 82%, the total conversion of aldehyde and alcohol was 74.
Earned in%.

Comparative Example 1 In a 50 ml glass reactor, 0.300 g of tris (acetylacetonato) ruthenium and 0.396 g of triphenylphosphine (molar ratio, phosphorus / ruthenium = 2.
0), benzaldehyde 2.10 g, benzyl alcohol 2.01 g (molar ratio, aldehyde / alcohol = 1.
1) was added (ruthenium catalyst concentration 1.6% by weight), 17
Reaction was performed at 0 ° C. for 10 hours to obtain benzyl benzoate with a selectivity of 39% and a total conversion of aldehyde and alcohol of 33%.

Comparative Example 2 A 50 ml glass reactor was charged with dihydridotetrakis (triphenylphosphine) ruthenium (Aldric).
h) 0.216 g, benzaldehyde 0.503 g,
Benzyl alcohol 0.520 g (molar ratio, aldehyde / alcohol = 1.0) was added (ruthenium catalyst concentration 1.5% by weight), and the reaction was carried out at 170 ° C. for 10 hours. Obtained at a conversion of 47%.

As described above, in the examples of the present invention, the selectivity and the conversion rate are higher than those of the comparative examples using the complex catalyst having triphenylphosphine as a ligand, and the ester compound can be efficiently produced. I understand.

[0050]

INDUSTRIAL APPLICABILITY The present invention is not a complex catalyst using triphenylphosphine as a ligand, but (i) a monodentate phosphine ligand having one alkyl group and two aryl groups as substituents, (ii) 2 A group consisting of a monodentate phosphine ligand having one alkyl group and one aryl group as a substituent, and (iii) a bidentate phosphine ligand having a phosphorus atom bonded to both ends of the alkyl chain represented by the above structural formula. Since a Group 8 transition metal complex having at least one ligand selected from is used in the method for producing an ester compound,
Without the need for additives such as oxygen and hydrogen acceptors,
Further, the ester compound can be efficiently produced in a short time without any equilibrium restriction.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazunari Takahashi             3-10 Shiododori, Kurashiki City, Okayama Prefecture Mitsubishi Chemical             Within the corporation F-term (reference) 4H006 AA02 AC48 BA22 BA23 BA48                       BC31 BJ50                 4H039 CA66 CC40

Claims (4)

[Claims] 1. A method for producing an ester compound by dehydrogenating a mixture of aldehydes and alcohols in a liquid phase, comprising: (i) a monodentate phosphine having one alkyl group and two aryl groups as substituents. Ligand, (i
i) a monodentate phosphine ligand having two alkyl groups and one aryl group as substituents, and (iii) a bidentate phosphine ligand having a phosphorus atom bonded to both ends of an alkyl chain represented by the following structural formula. A method for producing an ester compound, which comprises using a Group 8 transition metal complex catalyst having at least one ligand selected from the group consisting of: [Chemical 1] (In the formula, A, B, C and D represent an aryl group or an alkyl group, provided that at least one of A and B, and
At least one of C and D is an aryl group. Y represents an alkyl chain. ) 2. The method according to claim 1, wherein the Group 8 transition metal complex catalyst is a ruthenium complex catalyst. 3. The mixing ratio of aldehydes and alcohols is 1 to 4 in terms of molar ratio of aldehydes to alcohol.
The manufacturing method according to claim 1 or 2. 4. The production method according to claim 1, wherein the aldehydes and the alcohols have the same carbon skeleton.