JPH09241218A - Production of diaromatic carbonate and/or aliphatic-aromatic carbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain diaromatic and/or aliphatic-aromatic carbonate compound(s) useful as e.g. a raw material for polycarbonates in high yield. SOLUTION: This compound, for example, a diaromatic carbonate of formula I (Ar1 and Ar2 are each a monovalent aromatic group) such as diphenyl carbonate, is obtained by reaction between a diaromatic carbonate of formula II (R1 and R2 are each a monovalent aliphatic hydrocarbon group) and an aromatic monohydroxy compound of the formula, Ar1 OH in the presence of a catalyst of the formula, TiLnx Oy (Ln is a group 3A metal element; (x) is the atom ratio of the group 3A metal atom to titanium atom in the multiple oxide; (y) is the atom ratio of the oxygen atom to titanium atom in the multiple oxide) at 100-350 deg.C to produce an intermediate of formula III (e.g. methyl phenyl carbonate) which is then heated in the presence of the catalyst of the formula, TiLnx Oy .

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a diaromatic carbonate and / or an aliphatic / aromatic carbonate. More specifically, a di-aliphatic carbonate or an aliphatic / aromatic carbonate is reacted with an aromatic monohydroxy compound to efficiently produce a di-aromatic carbonate and / or an aliphatic / aromatic carbonate in a high yield. It is about how to do it.

[0002]

2. Description of the Related Art Diaromatic carbonate represented by diphenyl carbonate is a useful compound as a raw material for polycarbonate. It is well known that an aromatic monohydroxy compound is reacted with a di-aliphatic carbonate or an aliphatic / aromatic carbonate to produce a di-aromatic carbonate. This reaction is represented by the following formula (1)-
It is represented by (3).

[0003]

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(In each of the above formulas, R represents an alkyl group and Ar represents an aryl group.) Of the above three reactions, the reactions of the formulas (1) and (2) include standard formation energy and free energy. As predicted from the calculations, the chemical equilibrium in the endothermic reaction is biased toward the raw material system side, and the activation energy is large and the reaction rate is slow, so it is the target product.

[0005]

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The yield of is low.

Therefore, in order to efficiently carry out these reactions, the aliphatic alcohol (ROH), which is a low-boiling product, is continuously removed from the system, and at the same time, the activation energy is lowered, which is a suitable catalyst. It is necessary to use.

Therefore, various compounds have been proposed as such catalysts. For example, AlX ₃ , Ti
X ₃ , TiX ₄ , VX ₄ , VoX ₃ , VX ₆ , Zn
Lewis acids such as X ₂ and FeX ₂ (X is halogen, acetoxy, alkoxy or aryloxy) and transition metal compounds capable of forming Lewis acids have been proposed (Japanese Patent Publication No. 56-42577). 51-105032
Japanese Patent Laid-Open Publication No. 60-173016). However, such Lewis acids are not only suitable for industrial use because they are highly corrosive, but also have a slow reaction rate and an insufficient yield.

Further, a method using an organic metal compound such as an organic tin compound or an organic titanium compound as a catalyst (JP-A-60-1).
No. 69444, JP-A-60-1694445, and JP-A-1-265083) are also proposed. However, since these organometallic compounds have a vapor pressure, they are When the aromatic carbonate is distilled off from the reaction mixture, it is mixed in the product,
It has the drawback of being difficult to separate from the complete catalyst.

On the other hand, a method using a neutral or basic lead compound has also been proposed (see JP-A-1-93560), but the reaction rate is rather slow, and the desired reaction can be carried out efficiently even in a large amount. It is not sufficient as a catalyst to carry out.

Other methods have been disclosed in which an alkali metal or alkaline earth metal compound is used as a catalyst (see JP-A-56-25138), but all of them have low reaction activity and, in addition, decarboxylation. There are many by-products of ether compounds from the reaction. Further, in Japanese Patent Laid-Open No. 1-265064, Sc, Cr, Mo, W, Mn, Au, Ga, In,
A method using Bi, Te, and a lanthanoid compound as a catalyst has been proposed, but all of the compounds shown therein have low reaction activity and many ether by-products, so that they are not practical.

Up to now, all the catalysts which are considered to have high reaction activity are in a homogeneous phase in the reaction system and are dissolved in the reaction system containing phenol as a main component. Probably the active species of the catalyst is believed to be the phenolate of the catalytic metal compound. The effect of lowering the activation energy of the di-aliphatic carbonate and transesterification reaction at the same time as forming a phenolate by contacting with phenol at a relatively high temperature to exchange a ligand, or in the case of an oxide, an addition dehydration reaction to form a phenolate. It is considered to be an effective catalyst species. These methods using a homogeneous catalyst are advantageous in maintaining high activity with a small amount of catalyst, but it is difficult to separate the catalyst from the reaction mixture.

By the way, the final target product of the present invention, the diaromatic carbonate, is a compound having a considerably high boiling point, and separation from the catalyst is accompanied by various difficulties even in the case of distillation separation. For example, when the reaction solution is distilled in the presence of a catalyst to separate the target diaromatic carbonate,
Decomposition such as decarboxylation or polymerization reaction may cause inefficiency in the purification process, or part of the catalyst may be mixed into the product as a volatile component. Separation of the decomposition product of the boiling point and the polymer from the catalyst is difficult, and the performance and loss of the catalyst are accompanied.

On the other hand, in the case of a heterogeneous catalyst, it is easy to separate the catalyst from the reaction solution, and the problems found in the case of the above homogeneous catalyst are solved. The heterogeneous catalysts that have been proposed so far include a mixed oxide of silicon and titanium obtained by hydrolyzing a halide of silicon and titanium together (JP-A-54-125617).
No.) and titanium dioxide having a high BET surface area (German Patent Publication DE-OS-4036594), but they generally have low catalytic activity and are not practically applicable.

[0015]

The object of the present invention is to find a catalyst having sufficient activity in spite of showing heterogeneity among compounds which have not been known as catalysts, and using the same, An object of the present invention is to provide a method for efficiently producing a diaromatic carbonate in a high yield without the above-mentioned drawbacks.

[0016]

Means for Solving the Problems As a result of intensive research to solve the above problems, the present inventors have found an excellent new catalyst and reached the present invention. That is, from an aromatic monohydroxy compound and a dialiphatic carbonate or an aliphatic-aromatic carbonate, there is no restriction on the material of the apparatus, and a new catalyst system capable of efficiently producing a diaromatic carbonate at a high reaction rate is found, The present invention has been completed.

Thus, according to the present invention, there is provided a method for producing a diaromatic carbonate and / or an aliphatic / aromatic carbonate by reacting an aromatic monohydroxy compound with a diaromatic carbonate or an aliphatic / aromatic carbonate. , As a catalyst, at least one selected from titanium and Group 3A metals, preferably Y, La, Nd and Sm.
A method is provided, characterized in that a complex oxide with a species of rare earth element is used.

Furthermore, according to the present invention, an aliphatic / aromatic carbonate or a mixture of an aliphatic / aromatic carbonate and a diaromatic carbonate, which is an intermediate product in the above reaction, is heated under the above catalyst. There is provided a method for producing a diaromatic carbonate.

The present invention also includes a method of using the above catalyst in the case of producing an aliphatic / aromatic carbonate by reacting an aromatic monohydroxy compound with a dialiphatic carbonate.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the diaromatic carbonate used as one of the starting materials is represented by the following general formula [1]

[0021]

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It is a compound represented by: In the general formula [1], R ₁ and R ₂ are the same or different from each other, and are monovalent aliphatic hydrocarbon groups. Specifically, it is a linear or branched alkyl group or cycloalkyl group having 1 to 12 carbon atoms, and examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, Examples thereof include an isobutyl group, a tert-butyl group, a pentyl group, a hexyl group and an octyl group, and examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group and a cyclohexyl group.

Specific examples of the dialiphatic carbonate represented by the above general formula [1] include dimethyl carbonate,
Dialkyl carbonates such as diethyl carbonate, diisopropyl carnate, and dicyclohexyl carbonate can be mentioned. Among them, dimethyl carbonate and diethyl carbonate are preferable, and dimethyl carbonate is particularly preferable. These can be used alone or as a mixture of two or more kinds.

On the other hand, the aromatic monohydroxy compound which is another raw material in the present invention is represented by the general formula [2].

Ar ₁ OH [2] In the above general formula [2], Ar ₁ represents a monovalent aromatic group,
Specifically, it is a substituted or unsubstituted phenyl group, naphthalene group, anthracene group, or the like.

Specific examples of such aromatic monohydroxy compounds include phenol, 2-cresol, 3-cresol, 4-cresol, 2,4-dimethylphenol,
2,6-dimethylphenol, 3,4-dimethylphenol, 2-ethylphenol, 3-ethylphenol,
4-ethylphenol, 2,4,6-trimethylphenol, 2,4,6-triisopropylphenol, 2-
Chlorophenol, 3-chlorophenol, 4-chlorophenol, 2-bromophenol, 3-bromophenol, 4-bromophenol, 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 2-nitrophenol, 3- Nitrophenol, 4
-Nitrophenol, α-naphthol, β-naphthol and the like can be mentioned, and these can also be used in a mixture. Of these, phenol is most preferred.

In the present invention, the aliphatic / aromatic carbonate contained in the product and used for producing the diaromatic carbonate with or without the dialiphatic carbonate is represented by the following general formula [3].

[0028]

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(In the above general formula [3], R ₁ and Ar
₁ is a compound represented by the above general formulas [1] and [2]), and specific examples thereof include methylphenyl carbonate, ethylphenyl carbonate, isopropylphenyl carbonate, and methyltolyl carbonate.

That is, this compound is usually produced by the reaction of the compound of the general formula [1] with the compound of the general formula [2] and can be said to be an intermediate raw material of the final target product, a diaromatic carbonate. Is.

The final product of the present invention has the following general formula [4]

[0032]

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(In the general formula [4], Ar ₁ and Ar ₂ are the same or different from each other and are the same as those in the general formula [2]).
It is a diaromatic carbonate represented by. Specifically, for example, diphenyl carbonate, ditolyl carbonate, di-p-chlorophenyl carbonate and the like.

In the present invention, titanium (Ti) is used as the catalyst.
And a complex oxide composed of at least one metal selected from the group 3A (former group IIIB) metals of the periodic table, so-called rare earth elements. These complex oxides are represented by the following formula [5]. TiLn _x O _y [5] (In the above formula [5], Ln represents a Group 3A metal element. _X represents the atomic ratio of the Group 3A metal atom contained in the composite oxide to the titanium atom, and y represents the composite oxidation. Indicates the atomic ratio of oxygen atoms contained in the material to titanium atoms)

Specific examples of the Group 3A metal used together with titanium in this composite oxide include Y, Sc, La, Ce,
Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, E
r, Tm, Yb and Lu can be mentioned. These three
Among the Group A metals, yttrium (Y) and lanthanum (L
When a), neodymium (Nd), samarium (Sm), or a mixture containing these is used as a mixed oxide with titanium, the reaction activity is high, the side reaction is small, and the existing amount is large, which is industrially easy to use. Therefore, it is particularly preferable.

Titanium element and 3 in the composite oxide used
The atomic ratio with the group A metal element can take any value, but since the oxide of titanium alone shows almost no activity as a catalyst, the ratio of the group 3A metal atom to titanium atom 1 is 0. It is preferably at least 01, more preferably at least 0.05.

The method for preparing the composite oxide catalyst of titanium and the Group 3A metal used in the present invention is not particularly limited, and can be adjusted by using a commonly used method for preparing a composite oxide. Generally, for example, "Sol-ge"
1 (sol-gel) method, there is a method of hydrolyzing a homogeneous mixed solution of titanium alkoxides and a Group 3A metal alkoxide with water or a weakly basic aqueous solution, and then firing in air. . In addition, there is used a method in which a mixture of titanium and metal chlorides, nitrates, sulfates, oxalates, acetates, organic acid salts, carbonates, hydroxides, etc., which is as uniform as possible, is fired in the air.

Since the composite oxide of the catalyst used in the present invention is used as a liquid phase or gas phase heterogeneous catalyst, it is preferable that it is porous and has a large specific surface area because high catalytic activity can be obtained. The specific surface area of the catalyst is at least 5 m ² / g
The above is necessary.

As the shape of the composite oxide catalyst to be used, a solid powder can be used as it is, but in consideration of the liquid permeability during the reaction and the separability of the catalyst after the reaction, it is formed into a granule or a pellet. Can be used.

In preparing the novel composite oxide catalyst used in the present invention, a suitable binder or carrier can be used, if necessary. As the binder, those that enhance the mechanical strength of the heterogeneous catalyst as a whole,
Specifically, silica sol, alumina sol or the like can be used to the extent that catalyst performance is not hindered. The carrier is used for the purpose of dispersing the catalyst oxide on the surface thereof to improve the efficiency of the catalytic reaction and improve the separability of the catalyst component and the reaction product after the reaction. Specific examples thereof include silica, alumina, silica-alumina, titania, zirconia, titania-zirconia, silica-titania, silica-zirconia, alumina-titania, inorganic carriers such as alumina-zirconia,
Examples include clay minerals such as diatomaceous earth, kaolinite, montmorillonite, and talc.

The above-mentioned composite oxide catalyst is generally used in a catalytic amount for the reaction of an aromatic monohydroxy compound with a diaromatic carbonate or an aliphatic / aromatic carbonate and for the disproportionation reaction of an aliphatic / aromatic carbonate. When used, the desired diaromatic carbonate can be obtained.

The reaction temperature is generally 100 to 350 ° C, preferably 120 to 300 ° C. If it is lower than this temperature range, the reaction rate is not sufficient, and if it exceeds this temperature range, side reactions such as decomposition may occur, which is not preferable.

In this reaction, since the equilibrium of the reaction is biased toward the raw material side as described above, alcohol (R ¹ OH or R ² OH) which is a low boiling point component of the product is continuously distilled. It is advisable to perform it while removing it by such a method. By such a method, a reaction which is disadvantageous in chemical equilibrium can be promoted toward the production system.

On the other hand, the chemical equilibrium is governed by the reaction temperature, but in general, according to Boltzmann's law, reactions that are disadvantageous to the product system in equilibrium can be improved by raising the reaction temperature, so this reaction also allows side reactions. In many cases, it is preferable to carry out the treatment at as high a temperature as possible within the range. Therefore, when a low-boiling substance such as dimethyl carbonate or diethyl carbonate is used as the raw material dialiphatic carbonate, the reaction system may be pressurized to some extent to maintain a relatively high reaction temperature.

Further, the alcohol of the reaction product forms an azeotrope with the starting di-aliphatic carbonate, so that when the reaction is carried out while the alcohol is removed by distillation, the starting di-aliphatic carbonate is accompanied. Therefore, a method is adopted in which the alcohol and the dialiphatic carbonate are separated by another means such as extraction from the distillate and the latter is returned to the reaction system, but the reaction is carried out in a pressure system to make the azeotropic composition more alcohol side. To reduce the amount of di-aliphatic carbonate entrained in the reaction system, or a solvent that causes azeotropy with alcohol in the reaction system (hexane, heptane, cyclohexane and other aliphatic hydrocarbons, benzene and other aromatic hydrocarbons or low boiling point solvents). There is a method in which only alcohol is efficiently and continuously removed by adding (esters, ethers, etc.), and the equilibrium reaction to the production system can be further promoted.

In the present invention, since the catalyst does not substantially dissolve in the reaction system and becomes a heterogeneous catalyst, it is easy to separate the catalyst after the reaction by a simple method such as filtration and reuse it as it is. It can be carried out.

Thus, according to the method of the present invention, a diaromatic carbonate and an aliphatic / aromatic carbonate can be obtained. However, the aliphatic / aromatic carbonate undergoes a disproportionation reaction in the presence of the above catalyst, and The di-aliphatic carbonate (low boiling point) generated by the homogenization reaction is excluded outside the system first, and the di-aromatic carbonate remains, so after the reaction (disproportionation) is completed, only the di-aromatic carbonate remains. Become. If it is isolated by distillation or the like, the final objective diaromatic carbonate can be obtained.

[0048]

The present invention will be described below with reference to examples.
It goes without saying that the invention is not limited to these examples.

Example 1 A 200 ml flask was charged with 94 g (1 mol) of phenol and sol-go as a catalyst.
4.0 g of a composite oxide catalyst (NdTiO _y , y = 3.5 (theoretical value) is shown) having a composition of Nd / Ti (atomic ratio) = 1/1 prepared by the method 1 was added, and the temperature of the oil bath was adjusted. While maintaining the temperature at 200 ° C. or higher, dimethyl carbonate was fed into the reactor at a rate of 7.5 g / hr. Next, a distillation column having a height of 60 cm was attached to the flask, and methanol produced from the upper part of the column was distilled off together with dimethyl carbonate, and a total of 40 g of dimethyl carbonate was reacted. After completion of the dropwise addition, the mixture was further heated and reacted for 30 minutes and then analyzed by gas chromatography to obtain 4.7 g of diphenyl carbonate (DPC) and 4.8 g of methylphenyl carbonate (MPC). Then, production of 0.4 g of anisole (AN) was observed.

[Examples 2 to 5, Comparative Examples 1 to 4] Example 1
In, the same reaction was carried out by replacing only the catalyst with the composite oxide shown in the upper part of Table 1. Table 1 shows the results. Also,
The case where a single oxide catalyst (all prepared by the sol-gel method) is used as Comparative Examples 1 to 3 is shown in the lower part of Table 1. Note that DPC, MPC, and AN in the table have the same meanings as in Example 1.

[0051]

[Table 1]

[Examples 6 to 11] In the same manner as in Example 1, only the catalyst was purified by the sol-gel method to obtain Nd and Ti.
The reaction was carried out using various ratios of the composite oxides. The results are shown in Table 2, which shows that these composite oxides are highly active in a wide range of compositions of Nd and Ti.

[0053]

[Table 2]

[0054]

As described above, according to the method of the present invention, the aromatic dihydroxy compound and the di-aliphatic (or aliphatic / aromatic carbonate) are efficiently used as the final target product of the di-aromatic compound in a high yield. It becomes possible to produce carbonate.

Claims (7)

[Claims] 1. A method for producing a diaromatic carbonate and / or an aliphatic / aromatic carbonate by reacting an aromatic monohydroxy compound with a dialiphatic carbonate or an aliphatic / aromatic carbonate, as a catalyst A method comprising using a composite oxide of titanium and at least one selected from Group 3A metals. 2. A method for producing an aliphatic / aromatic carbonate by reacting an aromatic monohydroxy compound with a dialiphatic carbonate, wherein titanium and 3A are used as catalysts.
A method comprising using a composite oxide with at least one selected from group metals. 3. The method according to claim 1 or 2, wherein the reaction is carried out under a temperature condition of 100 to 350 ° C. 4. The method according to claim 1, wherein the Group 3A metal is at least one selected from Y, La, Nd and Sm. 5. The method according to any one of claims 1 to 4, wherein the aromatic hydroxy compound is phenol. 6. The method according to claim 1, wherein the di-aliphatic carbonate is dimethyl carbonate or diethyl carbonate. 7. An aliphatic / aromatic carbonate or a mixture of an aliphatic / aromatic carbonate and a diaromatic carbonate produced by the method according to any one of claims 1 to 6 in titanium and a Group 3A metal. A method for producing a diaromatic carbonate, which comprises heating the diaromatic carbonate in the presence of a composite oxide with at least one selected from the group consisting of: