JP3482765B2 - 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 polycarbonate.

[0002]

As a method for producing a diaryl carbonate, a method of reacting phosgene with an aromatic hydroxy compound in the presence of an alkali (JP-A-62-190146, etc.) or a catalyst for a dialkyl carbonate and an aromatic hydroxy compound is used. Method of transesterification in the presence (Japanese Patent Publication Sho 56
-42577, Japanese Patent Publication No. 1-5588, etc.)
Is well known. However, the former method using phosgene is not necessarily an industrially excellent method because phosgene itself is a highly toxic compound and a large amount of alkali is used. In addition, the latter method by transesterification is not sufficient in reaction rate in spite of using a highly active catalyst as described in many patents relating to this method. There is a problem such as requiring the device of.

As another method, there is known a method in which a diaryl oxalate is subjected to a decarbonylation reaction to produce a diaryl carbonate. However, this method has a slow reaction rate and the selectivity of the intended diaryl carbonate is extremely low. I have a problem. That is, in the method for producing diphenyl carbonate by boiling diphenyl oxalate in a distillation flask (Organic Synthesis Society Journal, 5, Report 47 (1948), 70),
The reaction rate is slow, phenol is by-produced as shown in the reaction formula of this document and is also isolated as a by-product, and carbon dioxide is also by-produced, and the selectivity of the target diphenyl carbonate is remarkably high. Get lower.

Also proposed is a method of producing carbonic acid diester by heating oxalic acid diester in the liquid phase at 50 to 150 ° C. in the presence of an alcoholate catalyst (USP45).
44507).

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for easily producing a diaryl carbonate at a sufficient reaction rate without using phosgene, which is a highly toxic compound. That is, an object of the present invention is to provide a method for producing a diaryl carbonate from a diaryl oxalate, which can produce the diaryl carbonate at a high reaction rate and a high selectivity.

[0006]

The object of the present invention is to heat a diaryl oxalate in the gas phase to cause a decarbonylation reaction in the presence of an oxide of an alkaline earth metal while adding an aromatic hydroxy compound. It is achieved by the method for producing di-carbonate carbonate.

[0007]

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.

[0008]

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

The aryl group is (1) a phenyl group, (2) a substituent, (a) an alkyl group having 1 to 12 carbon atoms such as a methyl group or an ethyl group, (b) a methoxy group,
An alkoxy group having 1 to 12 carbon atoms such as an ethoxy group, (c)
Examples thereof include a nitro group, (d) a substituted phenyl group having a halogen atom such as a fluorine atom and a chlorine atom, and (3) a naphthyl group. Of these aryl groups, the phenyl group is particularly preferable.

The substituted phenyl group includes various isomers.
Examples of these isomers include (a) 2- (or 3
-, 4-) methylphenyl group, 2- (or 3-, 4-)
A 2- (or 3-, 4-) alkylphenyl group having an alkyl group having 1 to 12 carbon atoms such as an ethylphenyl group,
(B) 2- (or 3-, 4-) methoxyphenyl group, 2
-(Or 3-, 4-) ethoxyphenyl group etc. carbon number 1
2- (or 3-, 4-) having ~ 12 alkoxy groups
Alkoxyphenyl group, (c) 2- (or 3-, 4-)
2- (or 3-, 4-) having a halogen atom such as nitrophenyl group, (d) 2- (or 3-, 4-) fluorophenyl group, 2- (or 3-, 4-) chlorophenyl group
A halophenyl group is mentioned.

In the present invention, the above decarbonylation reaction is carried out in the presence of an oxide of an alkaline earth metal as a catalyst. As the oxide of alkaline earth metal, oxides of magnesium, calcium, strontium, barium and the like are used. Among the alkaline earth metals, magnesium and calcium are preferable, and magnesium is particularly preferable.

Specific examples of the alkaline earth metal oxides include magnesium oxide, calcium oxide, strontium oxide, and barium oxide. Among the above alkaline earth metal oxides, magnesium oxide and calcium oxide are preferable, and magnesium oxide is particularly preferable.

Further, halides of alkaline earth metals such as magnesium chloride, calcium chloride, strontium chloride, barium chloride, magnesium bromide, calcium bromide, strontium bromide and barium bromide, magnesium formate, calcium formate and formic acid. Strontium, barium formate, magnesium acetate, calcium acetate, strontium acetate, barium acetate, magnesium oxalate,
Aliphatic mono- or dicarboxylic acid salts of alkaline earth metals such as calcium oxalate, strontium oxalate and barium oxalate, and water of alkaline earth metals such as magnesium hydroxide, calcium hydroxide, strontium hydroxide and barium hydroxide. Oxides, carbonates of alkaline earth metals such as magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, nitrates of alkaline earth metals such as magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate, magnesium sulfate, Sulfates of alkaline earth metals such as calcium sulfate, strontium sulfate, and barium sulfate are allowed to coexist with oxygen as necessary, and 1
Those obtained by heat treatment at 00 to 600 ° C. can also be used as the alkaline earth metal oxide of the present invention.

Among those obtained by the above heat treatment, those obtained by heat treatment of a magnesium halide, an aliphatic mono- or dicarboxylic acid salt, a hydroxide, a carbonate or a sulfate, and a calcium salt. Those obtained by heat treatment of halides, aliphatic mono- or dicarboxylic acid salts, hydroxides, carbonates, or sulfates are preferable, and particularly halides of magnesium, aliphatic mono- or dicarboxylic acid salts, hydroxides. What is obtained by heat-treating a carbonate, a carbonate, or a sulfate is preferable.

As the aromatic hydroxy compound, a compound in which a hydroxyl group is bonded to the above aryl group is used. Specifically, for example, phenol, 2- (or 3
-, 4-) methylphenol, 2- (or 3-, 4-)
Alkylphenol having an alkyl group having 1 to 12 carbon atoms such as ethylphenol, and 1 to 12 carbon atoms such as 2- (or 3-, 4-) methoxyphenol and 2- (or 3-, 4-) ethoxyphenol. Alkoxyphenol having an alkoxy group, nitrophenol having a nitro group such as 2- (or 3-, 4-) nitrophenol,
A halogenophenol having a halogen atom such as 2- (or 3-, 4-) fluorophenol and 2- (or 3-, 4-) chlorophenol, and naphthol such as α-naphthol and β-naphthol are used. Of these aromatic hydroxy compounds, phenol is particularly preferable.

Although the alkaline earth metal oxide can be used as it is, the alkaline earth metal hydroxide or carbonate is used as a catalyst carrier such as alumina, silica, silica-alumina, zeolite, diatomaceous earth, pumice, and activated carbon. It is also possible to support a nitrate, a sulfate and / or a compound of the above-mentioned alkaline earth metal and then heat-treat it in the presence of oxygen to use it as a supported catalyst. At this time, the amount of the alkaline earth metal compound supported is usually 0.1 to 50% by weight, preferably 0.5 to 30% by weight, as an alkali metal with respect to the catalyst carrier.

The method for preparing the above-mentioned supported catalyst does not need to be special, and examples thereof include an impregnation method, a kneading method, a deposition method,
Catalyzing alkaline earth metal hydroxides, carbonates, nitrates, sulfates and / or the above-mentioned alkaline earth metal compounds by commonly used methods such as coprecipitation, evaporation to dryness, and ion exchange. After loading on a carrier, drying and baking (heat treatment)
Can be prepared by the method described below. Drying is performed in air at 50 to 100 ° C., and firing (heat treatment) is performed in air at 150 to 100 ° C.
It is usually done at 500 ° C.

The alkaline earth metal oxide or its supported catalyst is used in the form of powder, granules or a molded body. The size is not particularly limited, but powders having a particle size of 20 to 100 μmφ, granular particles having a particle size of 4 to 200 mesh, and a molded product having a length of 0.5 to 10 mm are preferably used.

In the present invention, the decarbonylation reaction of diaryl oxalate is carried out by adding an aromatic hydroxy compound in the presence of the above-mentioned alkaline earth metal oxide as a catalyst.
It is carried out by heating the diaryl oxalate in the gas phase. At this time, according to the above reaction formula, diaryl carbonate is produced from diaryl oxalate and carbon monoxide is produced. The catalyst may be used in either a fixed bed or moving bed form, but is usually used in a fixed bed. Further, as the reactor, for example, a reaction tube made of stainless steel or quartz is used.

The reaction is usually carried out in a gas phase continuous system. In the gas phase continuous reaction, the reaction temperature is usually 200 to 600 ° C., preferably 300 to
Supplying a raw material gas containing a diaryl oxalate, an aromatic hydroxy compound and an inert gas (nitrogen gas, etc.) under the conditions of 500 ° C. and a gas hourly space velocity of 10 to 10,000 hr ⁻¹ , preferably 50 to 5000 hr ^−1. Done by The reaction pressure is not particularly limited as long as the reaction can be carried out in the gas phase, but it is usually preferable to carry out the reaction under normal pressure or reduced pressure.

In this case, the aromatic hydroxy compound is added to the reactor as long as the gas hourly space velocity is within the above range.
It does not matter whether it is in a gas state or a liquid state. Alternatively, the aromatic hydroxy compound may be melted or dissolved in advance with the diaryl oxalate and added. The aromatic hydroxy compound added in the liquid state is vaporized in a vaporizer or a vaporization layer above the reactor, and introduced into the reactor as a raw material gas together with diaryl oxalate and an inert gas (nitrogen gas or the like). The amount of the aromatic hydroxy compound added is usually 0.1 to the diaryl oxalate.
It is 50 times mol, preferably 0.5 to 10 times mol.

Diaryl oxalates are, for example, solid state,
Diaryl oxalate in a molten state or in a state of being dissolved in a solvent is vaporized in advance in a vaporizer or a vaporization layer above the reactor, and is used as a source gas together with an aromatic hydroxy compound and an inert gas (nitrogen gas, etc.) as a reactor gas. Be introduced to.

Further, in the present invention, an aprotic polar solvent such as sulfolane, N-methylpyrrolidone or dimethylimidazolidone is reacted in order to dissolve and collect reaction products and the like attached to the tube wall during the reaction. It can also be supplied from the bottom of the tube. After the reaction, the produced diaryl carbonate is separated and purified by distillation or the like.

[0024]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples. The conversion of diphenyl oxalate and the selectivity of diphenyl carbonate were calculated by the following equations.

[0025]

[Equation 1]

[0026]

[Equation 2]

Example 1 A quartz glass reaction tube having an inner diameter of 10 mm was filled with 1 ml of magnesium hydroxide molded to have a diameter of 1 to 3 mm, the reaction tube was fixed vertically, and a mantle heater was attached around the reaction tube to supply nitrogen gas. While flowing, the temperature in the reaction tube is 450
The heating was controlled so that the temperature became ° C. After the heat treatment for 1 hour to generate magnesium oxide, the temperature of the reaction tube is 350 ° C.
Controlled to be. Then, under normal pressure, while flowing nitrogen gas, a diphenyl oxalate-phenol melt solution [diphenyl oxalate: phenol (molar ratio) =
1: 2] was introduced into the reaction tube, vaporized at the upper part of the reaction tube and supplied to the catalyst layer, and reacted at 350 ° C. for 15 hours. At this time, the supply amount of diphenyl oxalate is 4.4 mmol / h
The supply rates of r and phenol were 8.8 mmol / hr, and the space velocity of the raw material gas containing diphenyl oxalate, phenol and nitrogen gas was 5000 hr ⁻¹ . During the reaction, in order to dissolve and collect the reaction product adhering to the wall of the reaction tube, sulfolane was supplied at a position of 30 mm below the catalyst layer at 10 ml / hr by a metering pump.

The obtained reaction product was subjected to gas chromatography (column temperature: 130 to 170 ° C., inlet temperature: 180).
℃), the conversion of diphenyl oxalate was 25.0%, diphenyl carbonate 1.01 mmol
/ Hr (selectivity: 91.8%). In addition,
Formation of diphenyl carbonate from diphenyl oxalate was not recognized by the analytical procedure.

Comparative Example 1 The reaction and analysis were carried out in the same manner as in Example 1 except that only diphenyl oxalate was supplied to the catalyst layer by the micro feeder. As a result, the conversion rate of diphenyl oxalate was 13.6% and diphenyl carbonate was 0.37 mm.
It was produced with ol / hr (selectivity: 61.8%).

Example 2 One to three magnesium hydroxides molded in Example 1 were used.
The reaction and analysis were performed in the same manner as in Example 1 except that calcium oxide was generated instead of 1 ml of calcium hydroxide molded into mmφ. As a result, the conversion rate of diphenyl oxalate was 35.8% and diphenyl carbonate was 0.56 mmo.
It was produced at 1 / hr (selectivity: 35.6%).

Comparative Example 2 The reaction and analysis were carried out in the same manner as in Example 2 except that only diphenyl oxalate was supplied to the catalyst layer with the micro feeder in Example 2. As a result, the conversion rate of diphenyl oxalate was 33.6% and that of diphenyl carbonate was 0.46 mm.
It was produced with ol / hr (selectivity: 31.2%).

Comparative Example 3 The reaction and analysis were carried out in the same manner as in Example 1 except that the magnesium hydroxide molded in Example 1 was replaced with 1 ml of quartz beads (3 mmφ). As a result, the conversion rate of diphenyl oxalate was 12.0% and diphenyl carbonate was 0.16%.
It was generated at mmol / hr (selectivity: 30.3
%). The results of Examples 1 and 2 and Comparative Examples 1 to 3 are shown in Table 1.

[0033]

[Table 1]

Comparative Example 4 5.0 g (20.7) of diphenyl oxalate was placed in a 100 ml glass reactor equipped with a thermometer, a stirrer and a reflux condenser.
(mmol) and the space of the container was replaced with argon gas, and the temperature was raised to 330 ° C. 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, the container was cooled to room temperature and analyzed in the same manner as in Example 1. The conversion rate of diphenyl oxalate was 10.8% and the selectivity of diphenyl carbonate was 3%.
The yield was 7.7% and the yield was 4.1%.

Comparative Example 5 Diphenyl oxalate (5.0 g, 2) was placed in a stainless steel closed reactor having an internal volume of 90 ml equipped with a thermometer and a stirrer.
0.7 mmol), potassium phenolate 0.5 g
(3.8 mmol) and 5.0 g of tetrahydrofuran were added, and the space of the container was replaced with argon gas, then 10
The temperature was raised to 0 ° C. 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 container was cooled to room temperature and analyzed in the same manner as in Example 1, but the conversion of diphenyl oxalate was 0%, and formation of diphenyl carbonate was not observed.

[0036]

INDUSTRIAL APPLICABILITY According to the present invention, diaryl carbonate can be easily produced from diaryl oxalate with high reaction rate and high selectivity without using phosgene which is a highly toxic compound.

Continuation of the front page (56) Reference JP-A-8-325207 (JP, A) JP-A-8-333307 (JP, A) JP-A-9-255627 (JP, A) US Patent 4544507 (US, A) Patent 3206425 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) C07C 68/00-68/08 C07C 69/96 CA (STN) REGISTRY (STN) CASREAACT (STN)

Claims (3)

(57) [Claims] 1. A process for producing a diaryl carbonate, which comprises heating a diaryl oxalate in a gas phase to perform a decarbonylation reaction while adding an aromatic hydroxy compound in the presence of an oxide of an alkaline earth metal. 2. The method for producing a diaryl carbonate according to claim 1, wherein the aromatic hydroxy compound is added in an amount of 0.1 to 50 times by mole with respect to the diaryl oxalate. 3. The method for producing a diaryl carbonate according to claim 1, wherein the diaryl oxalate is diphenyl oxalate and the aromatic hydroxy compound is phenol.