JP3482786B2 - Preparation of diaryl carbonate - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a diaryl carbonate useful as a raw material for producing a polycarbonate.

[0002]

As a method for producing a diaryl carbonate, a method of decarbonylating diaryl oxalate to produce a diaryl carbonate is known, but this method has a problem that the yield of the intended diaryl carbonate is extremely low. have. For example, a method for producing diphenyl carbonate (diphenyl carbonate) by boiling diphenyl oxalate (diphenyl oxalate) in a distillation flask [Organic Synthesis Society, 5, report 47].
(1948), 70], which is also shown in the reaction formula described in this document and is also a byproduct of phenol as isolated as a by-product, and carbon dioxide is also a by-product of the target diphenyl carbonate. The yield will be significantly lower.

A method for producing a carbonate diester by heating the oxalate diester in the liquid phase at 50 to 150 ° C. in the presence of an alcoholate catalyst has also been proposed (US Pat. No. 4,544,507). However, in this method, as shown in the examples described, even if diphenyl oxalate is heated in the presence of a potassium phenolate catalyst, the main product is not the target diphenyl carbonate but the starting material. Is diphenyl oxalate. As described above, no method has been known that can produce diaryl carbonate with high yield by decarbonylation reaction of diaryl oxalate.

[0004]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a method for producing a diaryl carbonate by decarbonylating a diaryl oxalate to produce the diaryl carbonate with a high yield.

[0005]

The object of the present invention is achieved by a method for producing a diaryl carbonate characterized by heating a diaryl oxalate in the presence of an alkali metal carboxylate to carry out a decarbonylation reaction.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a diaryl carbonate is produced by a decarbonylation reaction of a diaryl oxalate represented by the following formula.

[0007]

[Chemical 1] (In the formula, Ar represents an aryl group)

Examples of the aryl group include (1) phenyl group, (2) substituents, (a) alkyl group having 1 to 12 carbon atoms such as methyl group and ethyl group, (b) methoxy group, ethoxy group. And the like, and a substituted phenyl group having a halogen atom such as a fluorine atom and a chlorine atom, and a (c) nitro group, and (3) a naphthyl group. Of these aryl groups, the phenyl group is preferred.

The substituted phenyl group includes various isomers.
These isomers include (a) 2- (or 3-, 4-)
2-having an alkyl group having 1 to 12 carbon atoms such as a methylphenyl group and a 2- (or 3-, 4-) ethylphenyl group
(Or 3-, 4-) alkylphenyl group, (b) 2-
(Or 3-, 4-) methoxyphenyl group, 2- (or 3
A 2- (or 3-, 4-) alkoxyphenyl group having an alkoxy group having 1 to 12 carbon atoms such as-, 4-) ethoxyphenyl group, and (c) 2- (or 3-, 4-) nitrophenyl group , (D) 2- (or 3-, 4-) halophenyl group having a halogen atom such as 2- (or 3-, 4-) fluorophenyl group, 2- (or 3-, 4-) chlorophenyl group, and the like. Is mentioned.

As the diaryl oxalate, diphenyl oxalate, bis (2-methylphenyl) oxalate, bis (3-methylphenyl) oxalate, bis (4-methylphenyl) oxalate, bis (2-chlorophenyl) oxalate, bis ( Specific examples include 3-chlorophenyl) oxalate, bis (4-chlorophenyl) oxalate, bis (2-nitrophenyl), bis (3-nitrophenyl) oxalate, and bis (4-nitrophenyl) oxalate. Moreover, other diaryl oxalates are synthesized based on known methods. Of these diaryl oxalates, diphenyl oxalate is preferred.

In the decarbonylation reaction of the present invention, an alkali metal carboxylate is used as a catalyst. Alkali metals (lithium, sodium, potassium, rubidium,
As the carboxylic acid salt of cesium or the like, an aliphatic carboxylic acid salt or an aromatic carboxylic acid salt of these alkali metals is used. Among the alkali metal carboxylates, the alkali metal aliphatic carboxylates are preferred.

Examples of the alkali metal carboxylates of alkali metals include lithium formate, sodium formate, potassium formate, rubidium formate, cesium formate, lithium acetate,
Alkali metals such as sodium acetate, potassium acetate, rubidium acetate, cesium acetate, lithium oxalate, sodium oxalate, potassium oxalate, rubidium oxalate, cesium oxalate, lithium pyruvate, sodium pyruvate, lithium lactate, sodium lactate Carbon number 1
The salt with the aliphatic carboxylic acid of 15 (aliphatic carboxylic acid salt of alkali metal) is mentioned. Examples of the alkali metal carboxylate of an alkali metal include an alkali metal such as lithium benzoate and sodium benzoate and a carbon number of 7 to
Salts of 15 with aromatic carboxylic acids (aromatic carboxylic acid salts of alkali metals) can be mentioned.

Although the alkali metal carboxylate can be used as it is, it can also be used by supporting it on a carrier such as alumina, silica, silica-alumina, zeolite, diatomaceous earth, pumice, and activated carbon. At this time, the supported amount of the alkali metal carboxylate is usually 0.1 to 50% by weight, preferably 0.5 to 30% by weight as the alkali metal with respect to the carrier.

The method for preparing the above-mentioned supported catalyst does not need to be special, and for example, it is usually carried out by an impregnation method, a kneading method, a deposition method, a coprecipitation method, an evaporation-drying method, an ion exchange method and the like. According to the method, it can be prepared by a method of supporting an alkali metal carboxylate on a carrier, followed by drying and baking. Drying is usually performed in air at 50 to 100 ° C, and firing is usually performed in air at 150 to 500 ° C.

The above-mentioned supported catalyst is used in the form of powder, granules or molded bodies. The size of the powder is not particularly limited, but in general, the powder has a diameter of 20 to 100 μmφ,
A granular material having a mesh size of 4 to 200 mesh and a molded product having a length of 0.5 to 10 mm are preferably used.

In the decarbonylation reaction of diaryl oxalate, the diaryl oxalate and an alkali metal carboxylate are put in a reactor, and the diaryl oxalate is usually heated at 100 to 450 ° C., particularly 160 to 400 ° C., and further 180 ° C. It is preferably carried out by heating in a liquid phase at ˜350 ° C. At this time, according to the above reaction formula,
Diaryl carbonate is produced from diaryl oxalate, and carbon monoxide is produced. The reaction pressure is usually atmospheric pressure, but is not particularly limited. The catalyst may be used alone or as a mixture of two or more kinds, and the amount thereof is usually 0.001 to 50 mol% as an alkali metal with respect to the diaryl oxalate,
It is preferably 0.01 to 20 mol%. Further, the catalyst may be dissolved or suspended in the reaction solution before use.

A solvent is not particularly required in the decarbonylation reaction, but an aprotic polar solvent such as sulfolane, N-methylpyrrolidone or dimethylimidazolidone can also be appropriately used. The material of the reactor is not particularly limited, and may be, for example, glass or stainless steel (SU
A reactor made from S) can be used. After the reaction, the produced diaryl carbonate is separated and purified by distillation or the like.

[0018]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples. The yield (mol%) of diphenyl carbonate was calculated for diphenyl oxalate. Example 1 A 50 ml glass flask equipped with a thermometer and a reflux condenser was charged with diphenyl oxalate (10.0 mmo).
1) and lithium acetate (3.4 mmol) were added, the temperature was raised to 265 ° C. under stirring, and then the decarbonylation reaction was carried out by heating at this temperature in the liquid phase for 3 hours under normal pressure. After completion of the reaction, the reaction solution was cooled to room temperature and subjected to gas chromatography ((column temperature: 130 to 170 ° C., inlet temperature: 18
At 0 ° C.), the yield of diphenyl carbonate was 12.6%. In addition, generation of diphenyl carbonate from diphenyl oxalate by the analytical operation was not observed.

Example 2 Reaction and analysis were conducted in the same manner as in Example 1 except that lithium lactate (2.0 mmol) was used instead of lithium acetate and the reaction temperature was changed to 250. As a result, the yield of diphenyl carbonate was 14.5%.

Example 3 Lithium acetate was replaced with lithium pyruvate (2.0 mmol)
Instead of the above, the reaction and analysis were performed in the same manner as in Example 1 except that the reaction temperature was changed to 250. As a result, the yield of diphenyl carbonate was 10.7%.

Comparative Example 1 Reaction and analysis were carried out in the same manner as in Example 1 except that lithium acetate was not added. As a result, generation of diphenyl carbonate was not recognized.

Comparative Example 2 Diphenyl oxalate (20.7 mmol) was placed in a 100 ml glass reactor equipped with a thermometer and a reflux condenser, the space of the container was replaced with argon gas, and the mixture was stirred at 330 ° C. The temperature was raised to. Then, under normal pressure, the decarbonylation reaction was carried out by heating (boiling) in the liquid phase at this temperature for 3 hours. After completion of the reaction, analysis was performed in the same manner as in Example 1 and the yield of diphenyl carbonate was 4.1%.

Comparative Example 3 A closed reactor made of stainless steel having a thermometer and an internal volume of 90 ml was charged with diphenyl oxalate (20.7 mmo).
1), potassium phenolate (3.8 mmol) and tetrahydrofuran (5.0 g) were added, the space of the container was replaced with argon gas, and the temperature was raised to 100 ° C. with stirring. Then, the decarbonylation reaction was carried out by heating in the liquid phase at this temperature for 3 hours. After completion of the reaction, the same analysis as in Example 1 was carried out, but no formation of diphenyl carbonate was observed. The results of Examples and Comparative Examples are shown in Table 1.

[0024]

[Table 1]

[0025]

Industrial Applicability According to the present invention, diaryl carbonate can be produced from diaryl oxalate with high yield.

Front page continuation (72) Inventor Yoshifumi Yamamoto 5 1978, Ogushi, Ube City, Yamaguchi Prefecture, Ube Laboratory, Ube Industries Ltd. (56) Reference JP-A-8-325207 (JP, A) JP-A-8- 333307 (JP, A) JP 9-255628 (JP, A) JP 9-295959 (JP, A) JP 10-53563 (JP, A) JP 10-101620 (JP, A) JP-A-10-101621 (JP, A) US Patent 4544507 (US, A) Patent 3206425 (JP, B2) Patent 3206452 (JP, B2) Patent 3206451 (JP, B2) (58) Fields investigated (Int.Cl) . ^7, DB name) C07C 68/00 - 68/08 C07C 69/96 CA (STN) REGISTRY (STN) CASREACT (STN)

Claims (2)

(57) [Claims] 1. A process for producing a diaryl carbonate, which comprises heating a diaryl oxalate in the presence of a carboxylate of an alkali metal to carry out a decarbonylation reaction. 2. The method for producing a diaryl carbonate according to claim 1, wherein the alkali metal carboxylate is an alkali metal aliphatic carboxylate.