JPH09124559A - Production of aromatic carbonic ester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject compound useful as a raw material for producing polycarbonates by a melt transesterification method in a good yield at a high reaction rate by reacting a specific dialkyl carbonate with an aromatic carboxylic acid aryl ester in the presence of a catalyst. SOLUTION: A compound of the formula R-OCOO-R (R is a 1-4C alkyl) is reacted with a compound of the formula: Ar-COO-Ar' [Ar, Ar' are each (alkyl, alkoxy, aryl, aryloxy or halogen-substituted) phenyl] in the presence of a catalyst such as a compound of the formula: Ti(OX)4 (X is a 1-4C alkyl, an aryl) [e.g. titanium tetramethoxide, titanium tetra (4-chlorophenoxide)] or a compound of the formula: Ti(OX)4 .XOH (e.g. titanium tetraphenoxide phenol adduct).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an aromatic carbonic acid ester. More specifically, the present invention relates to a method for producing an aromatic carbonic acid ester having at least one aromatic group by transesterifying a dialkyl carbonic acid ester. Aromatic carbonic acid ester is a compound useful as a raw material for melt transesterification polycarbonate.

[0002]

2. Description of the Related Art Aromatic carbonic esters have hitherto been produced by reacting an aromatic hydroxy compound with phosgene. However, phosgene is extremely toxic, the equipment is highly corrosive, and a large amount of alkali is required to neutralize the by-produced hydrogen chloride. And several attempts have been made.

For example, there has been proposed a method of oxidatively carbonylating an aromatic hydroxy compound and carbon monoxide as raw materials. However, these methods use expensive palladium as a main catalyst and require a cocatalyst, a desiccant, an oxidizing agent, and the like, so that the reaction system is very complicated. In addition, it is difficult to recover the catalyst, and the present situation is that the yield and the reaction rate have not reached the industrial level.

[0004] As another production method, a transesterification reaction between an aromatic hydroxy compound and an aliphatic carbonate is known. For example, Japanese Patent Publication No. 56-42577 discloses a method using a Lewis acid as a catalyst.
No. 73016 discloses a method using a mixture of a Lewis acid and a protonic acid as a catalyst. However, in each case, the reaction requires a long time of 5 to 24 hours, and the yield is not sufficient. In addition, JP-A-54-
In Japanese Patent No. 48733, a method using a tin compound as a catalyst is presented, but according to the description in the official gazette, a sufficient yield has not been obtained despite the reaction time of 30 hours. In addition, JP-A-57-176932.
JP, JP-A-60-169444, JP, JP-A-56
No. 25138, JP-A No. 1-265064 and the like show similar reactions, but none of them has solved the problem of slow reaction rate.

As a method for improving the reaction rate, JP-A-51-105032 and JP-A-56-1239 are known.
No. 48, it is proposed to use phenyl acetate instead of phenol. However, in this method, despite the use of expensive phenyl acetate, the use of by-produced methyl acetate was not shown.

As a method for improving this, US Pat. No. 4,533,504 proposes a method in which methyl acetate is used as ketene, and this is returned to phenyl acetate as a raw material by reacting this with phenol. . Similarly, JP-A-5-507060 describes a method of reacting methyl acetate with carbon monoxide to produce acetic anhydride, and reacting this with phenol to return it to phenyl acetate. However, it is difficult to say that any of these methods is practical because the step of returning to phenyl acetate is complicated.

As a result of examining the above problems, the present inventors have found that
It has already been found that it is effective to use aromatic carboxylic acid phenyl ester as a reactive species in place of phenyl acetate, and as a result of further investigation, in this reaction, most of ordinary transesterification catalysts have low activity. It became clear.

[0008]

As described above, no effective catalyst has been found in the reaction of an aromatic carboxylic acid aryl ester and a dialkyl carbonate, which is still satisfactory from an industrial point of view. It shouldn't be. The present invention provides a method for producing an aromatic carbonate ester from an aromatic carboxylic acid aryl ester and a dialkyl carbonate ester at a sufficient reaction rate.

[0009]

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that titanium-based catalysts are extremely effective among ordinary transesterification catalysts. The invention was completed.

That is, the present invention is characterized by reacting a dialkyl carbonate represented by the following general formula (1) with an aromatic carboxylic acid phenyl ester represented by the following general formula (2) in the presence of a catalyst. And a method for producing an aromatic carbonic acid ester.

Embedded image R—OCOO—R (1) Ar—COO—Ar ′ (2) (wherein R is a C ₁ -C ₄ alkyl group, Ar and Ar ′ are unsubstituted or an alkyl group, an alkoxy group, An aryl group, an aryloxy group, and a phenyl group substituted by halogen, which may be the same or different)

Further, in the present invention, (a) a dialkyl carbonic acid ester represented by the general formula (1) and an aromatic carboxylic acid aryl ester represented by the general formula (2) are reacted in the presence of a catalyst. (B) Aromatic carboxylic acid alkyl ester represented by the following general formula (3) obtained in step (a) and aromatic didroxy compound are reacted in the presence of a catalyst. From the step of producing an aromatic carboxylic acid aryl ester represented by the above general formula (2), and (c) using the aromatic carboxylic acid aryl ester as a part of the reactant of step (a). And a method for producing a carbonic acid ester.

Embedded image Ar—COO—R (3) (In the formula, R and Ar represent the same as above)

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention uses Ti (O) as a catalyst.
X) ₄ , Ti (OX) ₄ · PhOH (X is 1 to 4 carbon atoms
Alkyl group, phenyl group) of titanium or an adduct of these compounds with an aromatic hydroxy compound is used to react a dialkyl carbonic acid ester with an aromatic carboxylic acid aryl ester to form an aromatic carbonic acid ester. Is to be manufactured

Examples of the catalyst represented by the above formula include, for example, titanium tetramethoxide, titanium tetraethoxide, titanium tetra-n-propoxide, titanium tetraisopropoxide and titanium tetra-.
n-butoxide, titanium tetra-sec-butoxide, titanium tetra-tert-butoxide, titanium tetraphenoxide, titanium tetra (4-methylphenoxide), titanium tetrakis (2,4-dimethylphenoxide), titanium tetrakis (3,5)
-Dimethylphenoxide), titanium tetra (4-methoxyphenoxide) and titanium tetra (4-chlorophenoxide) are exemplified.

The catalyst in the present invention may be used alone as the above compounds, or may be used as a mixture with other catalysts used in this kind of reaction such as Lewis acid or protic acid. Further, the titanium alkoxide is converted into a titanium aryl oxide in the reaction system and is included in the catalyst of the present invention. Further, in the case of titanium alkoxide and aryl oxide, phenol, alcohol,
Easily with ketones, amines, etc., such as Ti (OPh) 4
It is known to form an adduct such as PhOH, but these adducts are also effective as the catalyst of the present invention.

The specific embodiment of the present invention is not particularly limited, but a dialkyl carbonic acid ester, an aromatic carboxylic acid aryl ester and the above catalyst are charged in a reactor,
By reacting, an aromatic carbonate, that is, an alkylaryl carbonate and a diaryl carbonate can be obtained. This reaction can be performed by either a batch method or a continuous method.

The reaction temperature in the present invention is 50 ° C. to 300 ° C.
A wide range of ℃ is possible, but preferably 90 ℃ ~ 24
It is performed in the range of 0 ° C. The reaction can be carried out under either atmospheric pressure or pressure, but when it is carried out at a temperature higher than the boiling point of the starting material, it is preferably carried out under pressure. Although the reaction time varies depending on other conditions, it is generally several minutes to several tens hours, preferably 30 minutes to 6 hours.

The amount of the catalyst used in the present invention is usually the amount of the aromatic carboxylic acid phenyl ester as a raw material,
It is used in the range of 0.0001 mol to 10 mol%, but there is no particular limitation.

Any molar ratio of the aromatic carboxylic acid aryl ester and the dialkyl carbonic acid ester may be used.
0.2 to 50 mol is usually suitable. At this time, by increasing the molar ratio of the dialkyl carbonate, an alkylaryl carbonate as an intermediate can be selectively obtained. When it is intended to obtain a carbonic acid diaryl ester, an alkylaryl carbonate ester as a reaction intermediate can be added in advance. The addition amount of the alkylaryl carbonate can be selected at an arbitrary ratio, but it is convenient that the change in the concentration of the alkylaryl carbonate before and after the reaction is small. As an example of such an addition amount, an aromatic carboxylic acid aryl ester 1
The amount is 0.1 to 10 mol, preferably 0.1 to 1 mol, and more preferably 0.2 to 0.5 mol per mol.

The aromatic carboxylic acid aryl ester represented by the general formula (2) in the present invention is specifically as follows.
Phenyl benzoate, phenyl o-, m- or p-methyl benzoate, phenyl 2,4-dimethyl benzoate 3,
Phenyl 5-dimethylbenzoate, phenyl 4-n-propylbenzoate, phenyl 4-isopropylbenzoate, 4
Phenyl-n-butylbenzoate, phenyl 4-isobutylbenzoate, phenyl 4-sec-butylbenzoate, 4
Phenyl-tert-butylbenzoate, phenyl 4-methoxybenzoate, phenyl 4-phenoxybenzoate, 4
-Phenyl chlorobenzoate, phenyl 2,4-dichlorobenzoate, 4-chlorophenyl o-methylbenzoate,
4-phenoxyphenyl 2,6-dimethylbenzoate and the like can be mentioned.

In carrying out the present invention, a solvent inert to the reaction is used, or in the presence of an inert gas,
Alternatively, the reaction can be performed under pressure with an inert gas. Needless to say, each of the raw materials used in the present invention is preferably pure.

The desired aromatic carbonate ester can be obtained from the reaction solution obtained by the above-mentioned method by a usual separation operation. The alkylaryl carbonate can be converted into a diaryl carbonate by returning it to the reaction solution as described above and using it as a starting material. For example, it is known per se as described in JP-B-58-48537. It is also possible to obtain a diaryl carbonate by the disproportionation reaction of.

[0022]

EXAMPLES The method of the present invention will be described with reference to the following examples, but the present invention is not limited to these examples.

Example 1 5.64 g (28.4 mmol) of phenyl benzoate, 20 g (222 mmol) of dimethyl carbonate and 0.13 g (0.30 mmol) of titanium tetraphenoxide were placed in an autoclave made of SUS316 having an internal capacity of 100 ml, and nitrogen was added. After pressurizing to 20 kg / cm ² , the reaction was carried out at 150 ° C. for 3 hours. After completion of the reaction, the reaction solution was diluted with acetone and then analyzed by gas chromatography. As a result, the conversion rate of phenyl benzoate was 92%, the yield of methylphenyl carbonate was 75%, and the yield of diphenyl carbonate was 5%. In addition,
The yield is based on phenyl benzoate.
(The same applies to the following examples)

Example 2 A SUS316 autoclave having an internal volume of 100 ml was charged with p.
-Toluyl phenyl benzoate 30 g (141 mmo
l), 7.17 g of methylphenyl carbonate (47 mmo
l), dimethyl carbonate 4.24 g (47 mmol), titanium tetraphenoxide 0.59 g (1.41 mmo)
l) was added and pressurized with nitrogen to 20 kg / cm ² , and then 1
The reaction was performed at 80 ° C. for 3 hours. After completion of the reaction, the reaction solution was diluted with acetone and then analyzed by gas chromatography. As a result, the conversion rate of phenyl p-toluylbenzoate was 37%,
The yield of diphenyl carbonate was 42%. In addition, 35 mmol of methylphenyl carbonate was recovered.

Example 3 34.2 g (151 of phenyl 2,4-dimethylbenzoate was placed in an autoclave made of SUS316 having an internal volume of 100 ml.
mmol), dimethyl carbonate 4.7 g (52 mmol),
Methylphenyl carbonate 7.2 g (47 mmol), titanium tetraphenoxide / phenol adduct 0.23 g
(0.45 mmol) was added, the pressure was increased to 5 kg / cm ² with nitrogen, and then the mixture was reacted at 220 ° C. for 2 hours. After completion of the reaction, the reaction solution was diluted with acetone and then analyzed by gas chromatography. As a result, the conversion rate of phenyl 2,4-dimethylbenzoate was 63% and the yield of diphenyl carbonate was 52%. In addition, 47 mmol of methylphenyl carbonate was recovered.

Example 4 30.0 g (151 mmol) of phenyl benzoate, 6.82 g (76 mmol) of dimethyl carbonate and 0.63 g (1.51 mmol) of titanium tetraphenoxide were placed in an autoclave made of SUS316 having an internal capacity of 100 ml, and nitrogen was added thereto. After pressurizing to 20 kg / cm ² , the reaction was carried out at 180 ° C. for 2 hours. After completion of the reaction, the reaction solution was analyzed by gas chromatography, and then the raw materials and products were distilled to dryness, and the obtained solid was used again as a catalyst. That is, an uncle amount of phenyl benzoate, dimethyl carbonate and titanium tetraphenoxide was added again to the obtained residue and the same reaction was performed. The above operation was repeated 3 times. The results are shown below.

[0027]

[Table 1] Table-1 Number of repetitions 1 2 3 4 ─────────────────────────────────── Methylphenyl carbonate yield Rate 24% 24% 23% 23% Diphenyl carbonate yield 19% 19% 20% 20%

Example 5 30 g (151 mmol) of phenyl benzoate, 6.82 g (75.7 mmol) of dimethyl carbonate and 0.02 g (0.045 mmol) of titanium tetraphenoxide were placed in an autoclave made of SUS316 having an internal capacity of 100 ml, and replaced with nitrogen. The mixture was then sealed and reacted at 200 ° C. for 2 hours. After completion of the reaction, the reaction solution was diluted with acetone and then analyzed by gas chromatography. As a result, the conversion rate of phenyl benzoate was 20%, the yield of methylphenyl carbonate was 15%, and the yield of diphenyl carbonate was 4%.

Example 6 34 g (151 mm) of phenyl 2,4-dimethylbenzoate was placed in an autoclave made of SUS316 having an internal volume of 100 ml.
ol), dimethyl carbonate 6.82 g (75.7 mmo)
l), 0.43 g of titanium tetraisopropoxide
Add (1.51 mmol) and add nitrogen at 20 kg / cm ^2.
After pressurizing, the mixture was reacted at 150 ° C. for 2 hours. After completion of the reaction, the reaction solution was diluted with acetone and then analyzed by gas chromatography. As a result, the conversion of phenyl 2,4-dimethylbenzoate was 35% and the yield of methylphenyl carbonate was 19%.
%, And the yield of diphenyl carbonate was 8%.

[0030]

Industrial Applicability According to the present invention, an aromatic carbonate ester can be produced from a dialkyl carbonate ester in a good yield, and its industrial significance is great.

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[Procedure amendment]

[Submission date] March 8, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 2

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention uses Ti (O) as a catalyst.
X) ₄ , Ti (OX) ₄ · X OH (where X is an alkyl group or an aryl group having 1 to 4 carbon atoms), an aryloxy compound of titanium, or an adduct of these compounds and an aromatic hydroxy compound is used. Then, the dialkyl carbonic acid ester and the aromatic carboxylic acid aryl ester are reacted to produce an aromatic carbonic acid ester.

Claims (5)

[Claims] 1. An aromatic compound characterized by reacting a dialkyl carbonate represented by the following general formula (1) with an aromatic carboxylic acid aryl ester represented by the following general formula (2) in the presence of a catalyst. Method for producing carbonate ester. Embedded image R—OCOO—R (1) Ar—COO—Ar ′ (2) (wherein R is a C ₁ -C ₄ alkyl group, Ar and Ar ′ are unsubstituted or alkyl groups, alkoxy groups, An aryl group, an aryloxy group, and a phenyl group substituted by halogen, which may be the same or different) 2. A catalyst comprising Ti (OX) ₄ , Ti (OX) ₄
The production of an aromatic carbonic acid ester according to claim 1, which is an aryloxy compound of titanium represented by PhOH (X is an alkyl group having 1 to 4 carbon atoms, a phenyl group) or an adduct of these compounds and an aromatic hydroxy compound. Method. 3. The method for producing an aromatic carbonic acid ester according to claim 1, wherein the catalyst is titanium tetraphenoxide or an adduct of titanium tetraphenoxide and phenol. 4. An aromatic compound obtained by reacting (a) a dialkyl carbonic acid ester represented by the general formula (1) with an aromatic carboxylic acid aryl ester represented by the general formula (2) in the presence of a catalyst. Step (b) of producing carbonic acid ester The aromatic carboxylic acid alkyl ester represented by the following general formula (3) obtained in step (a) and an aromatic hydroxy compound are reacted in the presence of a catalyst, And (c) using the aromatic carboxylic acid aryl ester represented by the general formula (2) as a part of the reactant in the step (a). A method for producing a carbonic acid ester, which is characterized. [Image Omitted] Ar-COO-R (3) (In the formula, R and Ar represent the same as above) 5. A dialkyl carbonate represented by the general formula (1) and an aromatic carboxylic acid aryl ester represented by the general formula (2) are reacted in the presence of a catalyst. A method for producing an alkylaryl carbonate represented by (4). Embedded image Ar—OCOO—R (4) (wherein Ar and R are the same as above)