JPH0959223A - Production of diaromatic carbonate and/or aliphatic-aromatic carbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject compound useful as a raw material for polycarbonates, etc., at a high reaction rate in a high yield in a state easy the recovery of a catalyst without limiting the materials of a device for produc ing the compound by reacting an aromatic monohydroxy compound with a dialiphatic or aliphatic and aromatic carbonate in the presence of a specific catalyst. SOLUTION: (B) An aromatic monohydroxy compound such as phenol is reacted with (C) a dialiphatic carbonate (e.g. dimethyl carbonate, diethyl carbonate) or an aliphatic and aromatic carbonate in the presence of (A) the divalent oxide of a lanthanide (e.g. La, Nd, Sm) as a catalyst at a reaction temperature of 100-350 deg.C. The component A usually has a specific surface area of >=5m<2> /g.

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 the method.

[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 formulas (1) to (3 )
Represented by

[0003]

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(In the above formulas, R represents an alkyl group and Ar represents an aryl group.)

Of the above three reactions, (1) and (2) are endothermic reactions as predicted by calculations of standard production energy and free energy, and the chemical equilibrium is biased toward the raw material system side, and Since the activation energy is large and the reaction speed is slow,

[0006]

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The yield of is low.

Therefore, in order to efficiently carry out these reactions, aliphatic alcohol (RO
It is necessary to use a suitable catalyst in order to continuously remove H) out of the system and at the same time lower the activation energy.

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

Further, a method using an organometallic compound such as an organotin compound or an organotitanium compound as a catalyst (JP-A-60-1).
69444, JP-A-60-169445 and JP-A-1-265083), these organometallic compounds have vapor pressures, so that 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 are known in which an alkali metal or alkaline earth metal compound is used as a catalyst (see JP-A-56-25138). However, 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,
Although a method using In, Bi, Te and a lanthanoid compound as a catalyst has been proposed, all of the compounds shown therein have low reaction activity and many ether by-products,
It cannot be used industrially.

The catalysts which have been considered to have a high reaction activity up to now have a homogeneous phase during the reaction and are dissolved during the reaction containing phenol as a main component. Probably the active species of the catalyst is believed to be the phenolate of the catalytic metal compound. Effective in 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 and by ligand exchange or addition dehydration reaction in the case of an oxide to form a phenolate and uniformly dissolving it. It is considered to be a catalytic species. In the methods using these homogeneous catalysts, it is advantageous to maintain high activity with a small amount of catalyst, but it is difficult to separate the catalyst from the reaction mixture.

The diaromatic carbonate which is the target product in the present invention 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, if 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 occur, resulting in poor efficiency in the purification step, or loss of catalyst activity. In some cases, a part becomes a volatile component and is mixed in the product, and even in the recovery and circulation of the catalyst, it is difficult to separate the decomposition product having a high boiling point and the polymer from the catalyst, 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. 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 (see JP-A-54-125617) and a high BET surface area. Titanium dioxide (German published patent DE-OS-4036594) and the like are available, but they generally have low catalytic activity and are not practically applicable.

[0016]

The object of the present invention is to find a catalyst having sufficient activity in spite of showing heterogeneity among compounds that have not been known as catalysts, and to use the catalyst. Another 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.

[0017]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems of the prior art, the present inventors have found an excellent new catalyst and reached the present invention. That is, the inventors of the present invention are capable of efficiently producing a diaromatic carbonate from an aromatic monohydroxy compound and a dialiphatic carbonate or an aliphatic / aromatic carbonate without a restriction on the material of the apparatus and at a high reaction rate. The catalyst has been found and the present invention has been completed.

Thus, according to the present invention, an aromatic monohydroxy compound and a dialiphatic carbonate or an aliphatic.
In a method for producing a diaromatic carbonate and / or an aliphatic / aromatic carbonate by reacting an aromatic carbonate, at least one trivalent metal selected from lanthanoid metals, particularly rare earth elements La, Nd and Sm, is used as a catalyst. There is provided a method characterized by using an oxide of

Furthermore, according to the present invention, the intermediate product in the above reaction, aliphatic / aromatic carbonate, or a mixture of aliphatic / aromatic carbonate and diaromatic carbonate is heated in the presence of the above catalyst. This provides a method for producing the final target product, 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 and a dialiphatic carbonate.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION In the method of the present invention, the dialiphatic carbonate used as a raw material has the general formula [1]

[0022]

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Is a compound represented by: The above formula [1]
Among them, R ₁ and R ₂ are the same or different and each is a monovalent aliphatic hydrocarbon group. 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,
Examples thereof include an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a hexyl group and an octyl group. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group and a cyclohexyl group. And so on.

Specific examples of the dialiphatic carbonate represented by the above formula [1] include dimethyl carbonate, diethyl carbonate, diisopropyl carbonate, dicyclohexyl carbonate and the like.
Dimethyl carbonate and diethyl carbonate are preferred, and dimethyl carbonate is most preferred. These may be used alone or as a mixture of two or more.

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

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

Specific examples of the aromatic monohydroxy compound 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 has the general formula [3].

[0029]

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(In the above formula [3], R ₁ and Ar ₁ are the same as those in the above formulas [1] and [2]), and specifically, for example, methylphenyl carbonate, ethylphenyl Carbonate, isopropyl phenyl carbonate, methyl tolyl carbonate and the like.

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

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

[0033]

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(In the above formula [4], Ar ₁ and Ar ₂ are the same or different and are the same as those in the above formula [2]), and specifically, for example, diphenyl carbonate, Examples thereof include ditolyl carbonate and di-p-chlorophenyl carbonate.

In the present invention, at least one selected from the trivalent oxides of lanthanoid metals is used as the catalyst. These trivalent oxides are compounds represented by the following formula [5].

Ln ₂ O ₃ [5] (In the above formula [5], Ln represents a lanthanoid metal element.) Specific examples of the lanthanoid metal (Ln) include La and C.
e, Pr, Nd, Pm, Sm, Eu, Gd, Tb, D
Examples thereof include y, Ho, Er, Tm, Yb and Lu. Among these lanthanoid (lanthanide) metal oxides, lanthanum oxide, neodymium oxide, samarium oxide, or a mixture containing them is preferable because it has a high reaction activity and a large amount of endurance, which is easy to industrially utilize.

As these oxide catalysts of lanthanoid metal, those commercially available in general can be used, but they can be prepared, for example, by the following method. That is, a method of firing these lanthanoid metal oxalates, acetates, nitrates, carbonates, hydroxides, etc. in the air,
Alternatively, a method in which a water-soluble salt such as a chloride, a nitrate or a sulfate is neutralized with an alkali, precipitated with a hydroxide or a carbonate, and then calcined in the air is used.

Since the oxide 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 is usually required to be at least 5 m ² / g or more.

As the shape of the 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, the oxide catalyst is formed into a granule or a pellet. Can be used.

In preparing the above oxide catalyst,
If necessary, a suitable binder or carrier can be used. The binder enhances the mechanical strength of the heterogeneous catalyst as a whole, and specifically, silica sol, alumina sol or the like can be used to the extent that the catalyst performance is not impaired. The carrier can be 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, alumina-zirconia and other inorganic carriers, diatomaceous earth, kaolinite, montmorillonite, Examples include clay minerals such as talc.

The above catalyst is generally used in a catalytic amount for the reaction of an aromatic monohydroxy compound with a dialiphatic carbonate or an aliphatic / aromatic carbonate, or a disproportionation reaction of an aliphatic / aromatic carbonate. Finally, the intended diaromatic carbonate can be obtained.

The reaction temperature is 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 is higher than 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 system as described above, alcohol (R ₁ OH or R ₂ OH) which is a low boiling point component of the product is continuously distilled or the like. It is advisable to carry out while removing by the 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 the highest temperature possible.
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 of separating the alcohol and the dialiphatic carbonate by another means such as extraction from the distillate and returning the latter to the reaction system is used, 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). For example, there is a method in which only alcohol is efficiently and continuously removed by adding (esters, ethers, etc.), and the parallel reaction to the production system can be further promoted.

In the method of the present invention, since the catalyst has a heterogeneous system, it is easy to separate the catalyst after the reaction by a simple method such as filtration and reuse it as it is.

Thus, according to the method of the present invention, an aromatic dicarbonate and an aliphatic / aromatic carbonate can be obtained. The aliphatic / aromatic carbonate undergoes a disproportionation reaction in the presence of the above catalyst to disproportionate. The di-aliphatic carbonate (low boiling point) produced by the reaction is first excluded from the system, and the di-aromatic carbonate remains. Therefore, after the reaction (disproportionation) is finally completed, only the di-aromatic carbonate remains. If it is isolated by distillation or the like, the final target 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 flask having a capacity of 200 ml was charged with 94 g (1 mol) of phenol and 2.0 g of commercially available samarium oxide Sm ₂ O ₃ as a catalyst, and 7.5 g while keeping the temperature of the oil bath at 200 ° C. or higher. Dimethyl carbonate was fed into the reactor at a rate of / hr. And
A distillation column having a height of 60 cm was attached to the flask, and methanol produced from the upper part of the flask was distilled off together with dimethyl carbonate to react a total of 40 g of dimethyl carbonate. After completion of dropping, the mixture was heated and reacted for another 30 minutes. The reaction product was analyzed by gas chromatography, and it was confirmed that 2.6 g of diphenyl carbonate (DPC) and 8.9 g of methylphenyl carbonate (MPC) were obtained. Almost no formation of anisole was observed.

Example 2 Preparation of catalyst: Samarium nitrate hexahydrate 8.9 in water 150
Soluble sodium carbonate 3.15 with stirring.
A solution of g in 100 ml of water was added dropwise over about 1 hour. After standing for a while, decantation was performed to remove the supernatant, and washing with pure water and filtration were repeated to remove water-soluble salts. 500 after drying the obtained precipitate
It was calcined at ℃ for 3 hours to obtain about 3.2 g of powder of samarium oxide Sm ₂ O ₃ .

In the same manner as in Example 1, phenol and dimethyl carbonate were reacted using 2.0 g of samarium oxide obtained above as a catalyst. As a result, DP
C6.8 g and MPC 5.2 g were obtained.

Example 3 The samarium oxide used in Example 2 was reacted, filtered off, washed with methanol and dried to obtain 1.9 g, which was directly used as a catalyst.
The reaction was carried out under exactly the same conditions as above. As a result, DPC6.
0 g and MPC 5.2 g were obtained.

Example 4 In the same manner as in Example 2, a 150 ml aqueous solution of neodynium nitrate hexahydrate 8.8 gka and the like was neutralized and precipitated with a 100 ml aqueous solution of 3.15 g of sodium carbonate, dried and then dried at 500 ° C. After firing for 3 hours, about 3.2 g of neodynium oxide was obtained. Using 2.0 g thereof as a catalyst, the reaction of phenol and dimethyl carbonate was carried out under the same conditions as in Example 1. As a result, DPC6.
0 g and MPC 6.8 g were obtained.

[Examples 5-8, Comparative Examples 1-2] Example 1
The reaction was carried out in the same manner as in, except that only the catalyst was replaced with the compounds shown in Table 1. The reactions all showed a heterogeneous system, but the tetravalent cerium oxide shown in Comparative Example 1 had no activity, and the stannic oxide shown in Comparative Example 2 did not show any activity at all. Table 1 shows the results.

[0055]

[Table 1]

[0056]

EFFECTS OF THE INVENTION According to the method of the present invention as described above, it is possible to carry out the reaction with excellent efficiency without the problems of the above-mentioned conventional methods, and it is possible to obtain the final target product of the diaromatic compound in a high yield. Carbonates can be produced. Moreover, since the catalyst used in the method of the present invention is a heterogeneous system insoluble in the reaction system, the catalyst can be separated and reused after the reaction.

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, and a lanthanoid as a catalyst. A method comprising using at least one selected from trivalent metal oxides. 2. A method for producing an aliphatic / aromatic carbonate by reacting an aromatic monohydroxy compound with a dialiphatic carbonate, wherein at least one selected from trivalent oxides of lanthanoid metal is used as a catalyst. A method characterized by the use of seeds. 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 at least one kind of La, Nd and Sm is used as the lanthanoid metal. 5. The method according to claim 1 or 2, wherein the aromatic hydroxy compound is phenol. 6. The method according to claim 1, wherein the dialiphatic 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 claim 1, further comprising a lanthanoid metal. A process for producing a diaromatic carbonate, which comprises heating in the presence of at least one selected from trivalent oxides to obtain a diaromatic carbonate.