JP2003238484A - Method for producing ester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently producing an ester in a short time without the need of any additive such as oxygen or a hydrogen acceptor nor any equilibrium limitation. <P>SOLUTION: The method for producing the ester comprises dehydrogenation of a mixture of an aldehyde and an alcohol in a liquid phase in the presence of a group 8 transition metal complex catalyst having a trialkylphosphine ligand. <P>COPYRIGHT: (C)2003,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 JP 2000-302727 A, for example, in the presence of molecular oxygen, palladium. Reactions using system 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. In addition, Japanese Patent Laid-Open No. 2001-3289
Japanese Patent Publication No. 66 discloses 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. However, since it is a gas phase method, it is a byproduct of the reaction. Hydrogen gas and the ester compound as a product coexist with the catalyst in a homogeneous phase. for that reason,
It was difficult to achieve high conversion and high selectivity due to equilibrium restriction due to the reverse hydrogenation reaction of the ester. 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 the above problems can be solved by using a complex catalyst having a trialkylphosphine ligand. The invention was completed.
That is, the gist of the present invention lies in the following (1) to (5). (1) In a method for producing an ester compound by dehydrogenating a mixture of aldehydes and alcohols in a liquid phase, a Group 8 transition metal complex catalyst having a trialkylphosphine ligand is used. Process for producing ester compound.

(2) The production method according to (1) above, wherein the Group 8 transition metal complex catalyst is a ruthenium complex catalyst. (3) The production method according to (2) above, wherein in the ruthenium complex catalyst having a trialkylphosphine ligand, the atomic ratio of phosphorus atom / ruthenium atom is 2 to 10.

(4) The mixing ratio of aldehydes and alcohols is 2 in terms of the molar ratio of aldehydes to alcohol.
The manufacturing method in any one of said (1)-(3) which is -5. (5) The production method according to any one of (1) to (4) above, wherein the aldehydes and the alcohols have the same carbon skeleton.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention uses a Group 8 transition metal complex catalyst having a trialkylphosphine ligand in a method for producing an ester compound by dehydrogenating a mixture of aldehydes and alcohols. It is characterized by. 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, 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 3-6 carbon chain, 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, from the viewpoint of reaction selectivity, it is preferable to select aldehydes and alcohols having the same carbon skeleton. 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, etc. Are preferred, and particularly preferred are benzaldehyde and benzyl alcohol, and octanal and 1
-A combination of octanols. For example, in the combination of benzaldehyde and benzyl alcohol, even if the aldehydes are hydrogenated during the dehydrogenation reaction,
This is because the alcohol produced is benzyl alcohol, which is the raw material, and the reaction can be continued without causing a decrease in selectivity.

The mixing ratio of aldehydes and alcohols is usually 1 in terms of the molar ratio of aldehydes to alcohols.
The above is preferably 2 or more, and is usually 10 or less, preferably 5 or less. 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 in the present invention is a Group 8 transition metal complex having a trialkylphosphine ligand. The trialkylphosphine ligands are tridecylphosphine, trinonylphosphine, trioctylphosphine and triheptylphosphine. , Trihexylphosphine, tripentylphosphine, tributylphosphine,
Tripropylphosphine, triethylphosphine, trimethylphosphine, dimethyloctylphosphine, dioctylmethylphosphine, dimethylheptylphosphine, diheptylmethylphosphine, dimethylhexylphosphine, dihexylmethylphosphine, dimethylpentylphosphine, dipentylmethylphosphine, dimethylbutylphosphine, dibutylmethylphosphine , Tricyclohexylphosphine, tribenzylphosphine,
Monodentate trialkylphosphines such as dimethylcyclohexylphosphine and dicyclohexylmethylphosphine;
1,2-bis (dimethylphosphino) ethane, 1,3-
Bis (dimethylphosphino) propane, 1,4-bis (dimethylphosphino) butane, 1,2-bis (diethylphosphino) ethane, 1,3-bis (diethylphosphino) propane, 1,4-bis ( Diethylphosphino)
Butane, 1,2-bis (dioctylphosphino) ethane, 1,3-bis (dioctylphosphino) propane,
1,4-bis (dioctylphosphino) butane, 1,2
-Bis (dihexylphosphino) ethane, 1,3-bis (dihexylphosphino) propane, 1,4-bis (dihexylphosphino) butane, 1,2-bis (dibutylphosphino) ethane, 1,3-bis And multidentate trialkylphosphines such as (dibutylphosphino) propane and 1,4-bis (dibutylphosphino) butane,
Among these, a trialkylphosphine having an alkyl group having 4 or more carbon atoms is preferable, and trioctylphosphine is particularly preferable.

The supply form of the Group 8 transition metal in the present invention is not particularly limited and may be a transition metal or a transition metal compound. Examples of the transition metal include ruthenium, iridium and rhodium, and ruthenium is preferable. As the transition metal compound, an oxide,
Examples thereof include hydroxides, inorganic acid salts, organic acid salts and complex compounds.

Specifically, ruthenium dioxide, ruthenium tetraoxide, ruthenium hydroxide, ruthenium trichloride, ruthenium tribromide, ruthenium triiodide, ruthenium nitrate, ruthenium acetate, tris (acetylacetonato) ruthenium, tris (hexafluoro) Acetylacetonato) ruthenium, tris (2,2,6,6-tetramethyl-3,
5-heptanedionato) ruthenium, sodium hexachlororuthenate, dipotassium tetracarbonylruthenate, pentacarbonylruthenium, cyclopentadienyldicarbonylruthenium, dibromotricarbonylruthenium, chlorotris (triphenylphosphine) hydridoruthenium, tetra (triphenylphosphine) di Hydridorthenium, tetra (trimethylphosphine) dihydridoruthenium, bis (tri-n-butylphosphine) tricarbonylruthenium, tetrahydridodecacarbonyltetraruthenium, dodecacarbonyltriruthenium, octadecacarbonylhexaruthenate dicesium, undecacarbonylhydridotri Tetraphenylphosphonium ruthenate, iridium trichloride, tribromide Dium, 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 (hexafluoroacetylacetonato) rhodium and the like. As described above, a ruthenium compound is preferable, and a ruthenium complex compound is more preferable, and tris (acetylacetonato) ruthenium and tris (hexafluoroacetylacetonato) ruthenium are particularly preferable.

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.

The Group 8 transition metal complex catalyst having a trialkylphosphine ligand in the present invention is preferably a ruthenium complex catalyst, and specific examples thereof include bis (acetylacetonato) bis (trimethylphosphine) ruthenium and bis (acetyl). Acetonato) bis (triethylphosphine) ruthenium, bis (acetylacetonato) bis (tripropylphosphine) ruthenium, bis (acetylacetonato) bis (tributylphosphine) ruthenium, bis (acetylacetonato) bis (trihexylphosphine) ruthenium , Bis (acetylacetonato) bis (trioctylphosphine) ruthenium, bis (acetylacetonato) bis (dimethylphosphinoethane) ruthenium, dihydridotetrakis (trimethylphosphine) ruthenium, Hydride tetrakis (triethylphosphine) ruthenium, dihydridotetrakis (tripropylphosphine) ruthenium, dihydridotetrakis (tributylphosphine) ruthenium, dihydridotetrakis (trihexylphosphine) ruthenium, dihydridotetrakis (trioctylphosphine) ruthenium, dihydridotetrakis (Tridecanylphosphine)
Examples thereof include ruthenium and dihydridobis (bisdimethylphosphinoethane) ruthenium, and preferably bis (acetylacetonato) bis (tributylphosphine) ruthenium, bis (acetylacetonato) bis (trihexylphosphine) ruthenium, and bis (acetylacetonato). ) Bis (trioctylphosphine) ruthenium, dihydridotetrakis (tributylphosphine) ruthenium, dihydridotetrakis (trihexylphosphine)
Examples thereof include ruthenium and dihydridotetrakis (trioctylphosphine) ruthenium. Particularly preferred are bis (acetylacetonato) bis (trioctylphosphine) ruthenium and dihydridotetrakis (trioctylphosphine) ruthenium.

In the present invention, by using a trialkylphosphine ligand, an ester compound can be produced at a higher reaction rate as compared with a conventionally known ruthenium catalyst using a triphenylphosphine ligand. can do.

The method for producing the Group 8 transition metal complex catalyst having a trialkylphosphine ligand in the present invention is not limited, but the Group 8 transition metal and / or the Group 8 transition metal compound may be used under a hydrogen pressure atmosphere. A method of synthesizing by stirring with a trialkylphosphine under a solvent or in the absence of a solvent, a Group 8 transition metal and / or a Group 8 transition metal compound, and an alcohol serving as a reaction component,
Examples include a method of synthesizing by heating in the presence of trialkylphosphine. In the present invention, among the above-mentioned methods, a method of mixing the latter trialkylphosphine ligand and a Group 8 transition metal and / or a Group 8 transition metal compound and heating the mixture is preferable.

In the present invention, the case of a ruthenium complex catalyst which is preferable as a Group 8 transition metal complex catalyst will be described in detail. In the ruthenium complex catalyst, the trialkylphosphine ligand and the ruthenium compound are used so that the atomic ratio of phosphorus atom / ruthenium atom is preferably 2 to 10, more preferably 2 to 5. Preferably, both are mixed and heated so that this atomic ratio is obtained.
If the amount of trialkylphosphine ligand is too small, it tends to be insufficient for preparing a catalyst and the reaction rate tends to decrease. Conversely, if the amount of trialkylphosphine ligand is too large,
Excessive amount of trialkylphosphine ligand reacts with the ester of the product and produces a large amount of high boiling by-products,
Selectivity tends to decrease.

The ligand-containing group 8 transition metal complex catalyst used in the method of the present invention may be synthesized in advance, isolated and used, or the precursors thereof may be added individually to the reaction system. The catalyst may be prepared and used in the reaction system. However, the ruthenium compound that is the catalyst source and an alcohol may cause a side reaction, which may lower the selectivity of the ester.Therefore, the catalyst is synthesized in advance and then added to the mixture of the alcohol and the aldehyde. Preferably.

The ester compound produced according to 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,
2- (diethylamino) ethyl methacrylate, 2- (dimethylamino) ethyl methacrylate, and the like,
Preferably an ester compound having a skeleton of interest,
Examples include 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.

Solvents usable in the present invention include
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.

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.

[0027]

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 selectivities and conversion rates were analyzed by gas chromatography for the sampled reaction solutions, and the internal standard method was used to determine the yields of gamma butyrolactone and the like, 1,4-butanediol and the like. The remaining amount of the raw material was determined and calculated from this value.

Example 1 22.6 g of tris (acetylacetonato) ruthenium and 209 g of trioctylphosphine were added to a 1 L stainless steel autoclave (molar ratio, phosphorus / ruthenium = 10), and a hydrogen pressure of 0.8 MPa / G. The reaction was carried out at 170 ° C. for 5 hours to obtain a trioctylphosphine solution of dihydridotetrakis (trioctylphosphine) ruthenium. To a 50 ml glass reactor, 0.44 g of the ruthenium catalyst solution prepared by the above method, 4.02 g of benzaldehyde and 1.02 g of benzyl alcohol (molar ratio, aldehyde / alcohol = 4) were added (ruthenium catalyst metal concentration 1 0.6% by weight) at 170 ° C. for 5 hours to obtain benzyl benzoate with a selectivity of 95% and a total conversion of aldehyde and alcohol of 70%.

Example 2 To a 1 L stainless steel autoclave, 40.6 g of tris (acetylacetonato) ruthenium and 112.5 g of trioctylphosphine were added (molar ratio, phosphorus / ruthenium = 2.8), and 0.8 MPa / Under hydrogen pressure of G, 15
The mixture was heated and stirred at 0 ° C. for 3 hours to obtain a solution of bis (trioctylphosphino) ruthenium bisacetylacetonate in trioctylphosphine. A glass reactor having a volume of 50 ml was charged with 1.07 of the ruthenium catalyst solution prepared by the above method.
g, benzaldehyde 3.19 g, and benzyl alcohol 0.82 g (molar ratio, aldehyde / alcohol = 4) (ruthenium catalyst metal concentration 1.6% by weight), 170
Reaction at ℃ for 8 hours, benzyl benzoate selectivity 8
The conversion was 6% and the total conversion of aldehyde and alcohol was 94%.

Example 3 In a 50 ml glass reactor, 0.30 g of tris (acetylacetonato) ruthenium, 0.558 g of trioctylphosphine (molar ratio, phosphorus / ruthenium = 2), 2.08 g of benzaldehyde, benzyl alcohol 2.0
1 g (molar ratio, aldehyde / alcohol = 1) was added (ruthenium catalyst metal concentration 1.6% by weight), 170 ° C.,
After reacting for 12 hours, the benzyl benzoate has a selectivity of 90.
%, Aldehyde and alcohol were obtained at a total conversion rate of 80%.

Comparative Example 1 A 50 ml glass reactor was charged with dihydridotetrakis (triphenylphosphine) ruthenium (Aldric).
h) 0.216 g, benzaldehyde 0.503 g,
0.520 g of benzyl alcohol (molar ratio, aldehyde / alcohol = 1) was added (ruthenium catalyst metal concentration: 0.2% by weight) and reacted at 170 ° C. for 10 hours to convert benzyl benzoate to a selectivity of 68% and total conversion of aldehyde and alcohol. It was obtained at a rate of 47%.

Comparative Example 2 A 50 ml glass reactor was charged with dihydridotetrakis (triphenylphosphine) ruthenium (Aldric).
h) 0.096 g, benzaldehyde 3.22 g, benzyl alcohol 0.826 g molar ratio, aldehyde / alcohol = 1) was added (ruthenium catalyst metal concentration 0.2).
% ) And reacted at 170 ° C. for 10 hours to obtain benzyl benzoate with a selectivity of 67% and a total conversion of aldehyde and alcohol of 25%.

Comparative Example 3 A catalyst solution (molar ratio, phosphorus / ruthenium = 2.8) was prepared using triphenylphosphine by the method described in Example 1. In a 50 ml glass reactor, 0.13 g of the prepared ruthenium catalyst, 0.503 g of benzaldehyde,
Benzyl alcohol 0.520 g molar ratio, aldehyde /
Alcohol = 1) was added (ruthenium catalyst metal concentration 1.
6% by weight) at 170 ° C. for 10 hours to obtain benzyl benzoate with a selectivity of 58% and a total conversion of aldehyde and alcohol of 48%.

As described above, in the examples using the complex catalyst having the trialkylphosphine as the ligand, the selectivity and the conversion rate are higher than those in the comparative example using the complex catalyst having the triphenylphosphine as the ligand. It is found that both are high and the ester compound can be efficiently produced.

[0035]

INDUSTRIAL APPLICABILITY In the present invention, a complex catalyst having a trialkylphosphine as a ligand, not a complex catalyst having a triphenylphosphine as a ligand, is used in the method for producing an ester compound. The ester compound can be efficiently produced in a short time without the need for additives such as the above and without any equilibrium constraint.

   ─────────────────────────────────────────────────── ─── 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 BA23 BA48 BC14                       BC31 BC32 BJ50                 4H039 CA66 CD10

Claims (5)

[Claims] 1. A method for producing an ester compound by dehydrogenating a mixture of aldehydes and alcohols in a liquid phase, wherein a Group 8 transition metal complex catalyst having a trialkylphosphine ligand is used. And a method for producing an ester compound. 2. The production method according to claim 1, wherein the Group 8 transition metal complex catalyst is a ruthenium complex catalyst. 3. The production method according to claim 2, wherein the ruthenium complex catalyst having a trialkylphosphine ligand has an atomic ratio of phosphorus atom / ruthenium atom of 2 to 10. 4. The mixing ratio of aldehydes and alcohols is 2 to 5 in terms of molar ratio of aldehydes to alcohols.
The manufacturing method according to any one of claims 1 to 3. 5. The production method according to claim 1, wherein the aldehydes and the alcohols have the same carbon skeleton.