JPH06184050A - Production of aromatic carbonate - Google Patents

Abstract

PURPOSE:To produce a diaromatic carbonate from an aromatic monocarboxylic compound and a dialiphatic carbonate in a high yield and in high selectivity. CONSTITUTION:The method for producing the diaromatic carbonate by reacting an aromatic monohydroxy compound with a dialiphatic carbonate or aliphatic.aromatic carbonate is characterized by using a thallium compound as a catalyst.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing aromatic carbonates. More specifically, it relates to a method for producing a diaromatic carbonate efficiently and in a high yield by reacting a dialiphatic carbonate or an aliphatic / aromatic carbonate with an aromatic monohydroxy compound.

[0002]

BACKGROUND ART It is well known that an aromatic monohydroxy compound is reacted with a dialiphatic carbonate or an aliphatic / aromatic carbonate to produce a diaromatic carbonate. This reaction is represented by the following formula. Be done.

[0003]

[Chemical 1]

(In the formula, R represents an alkyl group and Ar represents an aryl group.) Of these three reactions, (1) and (2)
Is an endothermic reaction, the chemical equilibrium is biased toward the original system, and the activation energy is large and the reaction rate is slow, as predicted from calculations of standard production energy and free energy.

[0005]

[Chemical 2]

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 ₄ , Ti
X ₃ , TiX ₄ , UX ₄ , VOX ₃ , VX ₆ , Zn
Lewis acids such as X ₂ and FeX ₃ (X is halogen, acetoxy, alkoxy, aryloxy) and transition metal compounds capable of forming Lewis acids are mentioned (see JP-A-51-105032). Such a Lewis acid is corrosive and is not preferable for the reactor.

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).
69444, JP-A-60-169445,
Japanese Patent Application Laid-Open No. 1-265083) is also proposed, but since these organometallic compounds have a vapor pressure, they are formed by distilling and separating the product diaromatic carbonate from the reaction mixture. It has the drawback that it is difficult to completely separate it from the catalyst because it is mixed into the product.

On the other hand, a method using a neutral or basic lead compound has also been proposed (see JP-A-1-93560). However, comparing the reaction rates, tin is used when a lead compound is used as a catalyst. A high reaction rate cannot be obtained even when compared with a compound, a titanium compound, etc. Therefore, it cannot be said that the catalyst is sufficient as a catalyst for efficiently carrying out the desired reaction.

[0011]

The object of the present invention is to find a catalyst having a sufficient activity from compounds which have not been known as catalysts and to use it to obtain the above-mentioned defects and high yield. To provide a method for efficiently producing diaromatic carbonate at a high rate.

[0012]

Means for Solving the Problems As a result of intensive studies to solve such problems, the present inventors have found that an aromatic monohydroxy compound and a di-aliphatic carbonate or an aliphatic / aromatic carbonate are The present inventors have found that it is possible to efficiently produce a diaromatic carbonate with a high yield by using a thallium compound as a catalyst in the reaction, and arrived at the present invention.

That is, according to the present invention, a thallium compound is used as a catalyst in a method for producing a diaromatic carbonate compound by reacting an aromatic monohydroxyl compound with a dialiphatic carbonate or an aliphatic / aromatic carbonate. This is a characteristic method.

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 present catalyst. A method for producing an aromatic carbonate is thereby provided.

Further, according to the present invention, an aromatic monohydroxyl compound and a dialiphatic carbonate are reacted to form an aliphatic
A method for producing an aromatic carbonate includes a method using a thallium compound as a catalyst.

The dialiphatic carbonate used as the raw material of the present invention has the general formula [1]

[0017]

[Chemical 3]

It is represented by In the formula, R ₁ and R ₂ are the same or different and each is a monovalent aliphatic hydrocarbon group. More 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, and an isobutyl group. Group, tert-butyl group, pentyl group, hexyl group or octyl group, and the cycloalkyl group includes cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group and the like.

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

The aromatic monohydroxy compound in the present invention is represented by the general formula [2].

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

As a concrete example, phenol, 2-, 3
-, 4-cresol, 2,4-dimethylphenol,
2,6-dimethylphenol, 3-, 4-dimethylphenol, 2-, 3-, 4-ethylphenol, 2 ',
4 ', 6-trimethylphenol, 2,4', 6-isopropylphenol, 2-, 3-, 4-chlorophenol, 2-, 3-, 4-bromophenol, 2-, 3-,
4-methoxyphenol, 2-, 3-, 4-nitrophenol, α-naphthol, β-naphthol and the like can be mentioned, and a mixture thereof may be used, but among them, phenol is most preferable.

The aliphatic / aromatic carbonate in the present invention has the general formula [3]

[0024]

[Chemical 4]

(In the formula, R ₁ and Ar ₁ are represented by the above formula [1]
And [2]), and specific examples thereof include phenylmethyl carbonate, phenylethyl carbonate, phenylisopropyl carbonate, and methyl-tolyl carbonate.

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

[0027]

[Chemical 5]

(In the formula, Ar ₁ and Ar ₂ are the same or different and are the same as those in the above formula [2]). Specifically, for example, diphenyl carbonate, ditolyl carbonate, di-p-chlorocarbonate and the like.

In the present invention, by using a thallium compound as a catalyst, the above formulas (1), (2),
By the reaction represented by the formula (3), the compound of the formula [4] is finally efficiently produced in a high yield from the compound of the formula [1] and the formula [2] via the compound of the formula [3]. Obtainable.

Examples of the thallium compound include monovalent and trivalent thallium compounds. For example, as the monovalent thallium compound, thallium (I) alkoxides such as thallium methoxide and thallium ethoxide, thallium phenoxide (I), thallium formate (I), thallium acetate (I), thallium malonate (I), Thallium (I) organic carboxylate such as thallium (I) benzoate, thallium (I) chloride, thallium (I) bromide, thallium (I) iodide, thallium (I) nitrate, thallium (I) sulfate, phosphorus In addition to salts such as thallium (I) acid, thallium carbonate (I), thallium hydroxide (I), thallium oxide (I) and the like can be mentioned. As the trivalent thallium compound,
Examples thereof include thallium (III) oxide, thallium chloride (III), thallium nitrate (III), and the like. In addition, various complex compounds of acetylacetonate derived from these may be used. Of these, monovalent thallium compounds are often preferred, and thallium oxide (I), thallium alkoxide (I), thallium acetate (I), and the like are preferred.

The above-mentioned catalyst is generally used in a catalytic amount to react the aromatic monohydroxy compound with a di-aliphatic carbonate or an aliphatic / aromatic carbonate and to
The target diaromatic carbonate can be obtained by using it in the disproportionation reaction of the aromatic carbonate.

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

In this reaction, since the parallelism of the reaction is biased to 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. It is good to do it while removing it. By such a method, a reaction which is disadvantageous in chemical equilibrium can be promoted.

On the other hand, the chemical equilibrium is governed by the reaction temperature, but generally, according to Boltzmann's law, reactions that are disadvantageous in equilibrium can be improved by raising the reaction temperature. It is often the case that higher temperatures give better results. Therefore, when an aliphatic dicarbonate having a low boiling point such as dimethyl carbonate or diethyl carbonate is used as the raw material, the reaction system can be pressurized to maintain a relatively high reaction temperature.

When a material having a much lower boiling point than an aromatic monohydroxy compound such as dimethyl carbonate or diethyl carbonate is used, the aromatic monohydroxy compound is always present in excess and is consumed in the reaction, for example. It is also possible to carry out the reaction efficiently by keeping the reaction temperature at a high temperature close to the boiling point of the high-boiling aromatic hydroxy compound by adding only the aliphatic carbonate while distilling off the alcohol.

[0036]

As described above, according to the present invention, the reaction between the aromatic monohydroxy compound and the dialiphatic carbonate is carried out in the presence of the thallium compound to give the diaromatic carbonate through the aromatic / aliphatic carbonate. It can be obtained with high yield and selectivity.

[0037]

The present invention will be described below with reference to examples.
Needless to say, the present invention is not limited to these examples.

[0038]

Example 1 Phenol 94 g in a 200 ml flask
(1 mol) and 4.0 g of thallium oxide as a catalyst
7.5g / while keeping the temperature of the oil bath above 200 ℃
Dimethyl carbonate is fed into the reactor at a rate of hr. Attach a distillation column with a height of about 40 cm to the flask and distill off the methanol produced from the top of the column together with dimethyl carbonate.
0 g of dimethyl carbonate are reacted. After completion of the dropwise addition, the mixture was heated for about 1 hour to distill off methanol and dimethyl carbonate and then analyzed by high performance liquid chromatography to obtain 19.9 g of diphenyl carbonate and 4.2 g of phenylmethyl carbonate.

[0039]

Example 2 Using the same apparatus as in Example 1 with a distillation column in a 200 ml flask, 94.0 g of phenol, 22.5 g of dimethyl carbonate and 2.0 g of thallium oxide were charged and heated to the top of the column. To near the boiling point of methanol (7
The reaction was carried out for 8 hours by distilling at 0 ° C or lower).
As a result, 10.0 g of diphenyl carbonate was obtained (yield: 18.9% based on dimethyl carbonate used).

[0040]

Example 3 In the same manner as in Example 2, 2.0 g of thallium oxide (Tl ₂ O ₃ ) was used instead of the first thallium oxide to carry out the reaction. As a result, 5.6 g of diphenyl carbonate was obtained.

[0041]

[Example 4] Thallium (I) acetate in the same manner as in Example 2.
It was subjected to the same reaction using (TlOCOCH ₃₎ 2.0g. As a result, 10.1 g of diphenyl carbonate was obtained.

[0042]

[Embodiment 5] Thallium (I) formate (T) as in Embodiment 2
The reaction was carried out using 2.0 g of 10OCOH). As a result, 10.2 g of diphenyl carbonate was obtained.

[0043]

[Example 6] As in Example 1, 94.0 g of phenol was added.
First thallium oxide (Tl) as a catalyst ₂O) 4.0 g is used
50 g of total supply of diethyl carbonate at a rate of 7.5 g / hr
7 hours in total while removing the main fraction of ethanol from the top
Reaction was carried out. After reaction, silica gel column chromatograph
Phenylethyl carbonate 7.6 determined by fee
g and 19.6 g of diphenyl carbonate were obtained.

Claims (6)

[Claims] 1. A method for producing a diaromatic carbonate by reacting an aromatic monohydroxy compound with a dialiphatic carbonate or an aliphatic / aromatic carbonate, wherein a thallium compound is used as a catalyst. how to. 2. A method for producing an aliphatic / aromatic carbonate by reacting an aromatic monohydroxy compound with a dialiphatic carbonate, wherein a thallium compound is used as a catalyst. 3. The method according to claim 1, wherein the reaction is carried out under a temperature condition of 100 to 350 ° C. 4. The method according to claim 1 or 2, wherein the aromatic monohydroxy compound is phenol. 5. The method according to claim 1, wherein the dialiphatic carbonate is dimethyl carbonate or diethyl carbonate. 6. An aliphatic / aromatic carbonate or an aliphatic / carbonate produced by the method according to claim 1.
A process for producing a diaromatic carbonate, which comprises heating a mixture of an aromatic carbonate and a diaromatic carbonate in the presence of a thallium compound.