JPH08325206A - Production of diaryl carbonate - Google Patents

Abstract

PURPOSE: To readily obtain a diaryl carbonate in good yield without using phosgene which is a compound having strong toxicity by carrying out a decarbonylation reaction of a diaryl oxalate at a specific temperature. CONSTITUTION: A diaryl oxalate is subjected to a decarbonylation reaction at 330-800 deg.C, especially 450-650 deg.C in a vapor phase. Furthermore, specifically, e.g. (A) the diaryl oxalate dissolved in a solid, a melted liquid or a solvent is previously vaporized and fed to a reactor together with (B) an inert gas such as nitrogen gas and (C) an inert filler such as quartz having no acid point, hydroxyl group, etc., in a feed amount of 10-1000g/L.hr (L is a unit volume; hr is a unit time) and a space velocity of 100-6000hr<-1> and then, the reaction of the diaryl oxalate is carried out under ordinary or reduced pressure.

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, but this method has a problem that the yield of the intended diaryl carbonate is extremely low. . That is,
A method for producing diphenyl carbonate by boiling diphenyl oxalate in a distillation flask (Organic Synthesis Society, 5, pp. 47).
(1948), 70), which is also shown in the reaction formula described in this document, and which is a byproduct of phenol, which is also isolated as a by-product, further produces carbon dioxide as a by-product, so that the target diphenyl carbonate There is a problem that the yield will be remarkably low.

Further, oxalate diester (oxalic acid diester) is added in an amount of 50 to 15 in the presence of an alcoholate catalyst.
A method for producing a carbonate diester (carbonic acid diester) by heating at 0 ° C. in a liquid phase has also been proposed (USP
No. 4544507), in this method, even if diphenyl oxalate (diphenyl oxalate) is heated in the presence of a potassium phenoxide catalyst, the main product is obtained as a raw material. The desired diphenyl carbonate (diphenyl carbonate) cannot be obtained.

[0005]

An object of the present invention is to provide a method for easily producing a diaryl carbonate 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 with a high yield.

[0006]

The object of the present invention is achieved by a method for producing a diaryl carbonate, which comprises subjecting a diaryl oxalate to a decarbonylation reaction in the gas phase at 330 to 800 ° C.

[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]

Embedded image (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.

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 and 2- (or 3-, 4-) chlorophenyl group. Can be mentioned.

The decarbonylation reaction of diaryl oxalate is performed by supplying diaryl oxalate to a gas phase reaction tube,
It is carried out by heating in the gas phase at 0 to 800 ° C, preferably 400 to 700 ° C, more preferably 450 to 650 ° C. At this time, according to the above reaction formula, diaryl carbonate is produced from diaryl oxalate and carbon monoxide is produced. If the reaction temperature is lower than 330 ° C., the decarbonylation reaction hardly occurs, and if it exceeds 800 ° C., the yield of diaryl carbonate decreases, which is not preferable.

The diaryl oxalate is supplied by, for example, vaporizing the diaryl oxalate dissolved in a solid, a melt or a solvent in advance in a vaporizer, a vaporization layer or the like, and introducing it into a reaction tube together with an inert gas such as nitrogen gas. Done by. The supply amount of the diaryl oxalate is usually 0.1 to 10000 g / l · hr, preferably 10 to 1000 g / l · hr per unit volume (l) and unit time (hr) of the reaction tube in the predetermined temperature range. is there. Also, the space velocity of the gas containing the vaporized inert gas such as oxalic acid diaryl and nitrogen gas is usually 10～10000Hr ^-1, preferably 100~6000hr ^-1. The reaction pressure is preferably atmospheric pressure or reduced pressure.

The reaction tube is preferably filled with a charge inert to this reaction in order to improve the thermal contact of the diaryl oxalate. The inert filler is preferably quartz, α-alumina or the like having no acid points or hydroxyl groups. As the reaction tube, for example, a reaction tube made of stainless steel, iron or quartz can be used. After the reaction, the produced diaryl carbonate is separated and purified by distillation or the like.

[0014]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples. The yield (mol%) of diaryl carbonate was determined for diaryl oxalate.

Example 1 A thermocouple for temperature measurement was attached to the side wall, and the inner diameter was 6.5 mm.
A quartz bead (3
(mmφ) 1 ml was filled and the whole reaction tube was heated to 610 ° C. while flowing nitrogen gas under normal pressure. Then, under normal pressure,
Diphenyl oxalate was vaporized at 200 ° C. in the vaporizer and introduced into the reaction tube together with nitrogen gas (50 ml / min) to start the reaction (reaction temperature: 610 ° C.). The total nitrogen gas flow rate during the reaction was 75 ml / min. During the reaction, since the product and the like that has come out of the reaction tube are dissolved and collected, sulfolane is added to the outlet of the reaction tube at about 6 ml / mi.
n. Diphenyl oxalate 1.5g (6.2m
mol) for 4 hours to carry out the reaction, and then the product is subjected to gas chromatography (column temperature: 130 to 170).
C., inlet temperature: 180.degree. C.), as a result, 0.90 g (4.2 mmol) of diphenyl carbonate was formed. The yield of diphenyl carbonate was 67.7%, and the ratio (selectivity) of diphenyl carbonate to the consumed diphenyl oxalate was 83 mol%. In addition, generation of diphenyl carbonate from diphenyl oxalate by the analytical operation was not observed.

Example 2 In Example 1, the entire reaction tube was heated to 570 ° C., diphenyl oxalate was vaporized, and nitrogen gas (10 m
Example 1 except that 1.70 g (7.0 mmol) of diphenyl oxalate was supplied in 5 hours by introducing it into the reaction tube together with (l / min) (reaction temperature: 570 ° C.).
Reaction and analysis were performed in the same manner as in. The total nitrogen gas flow rate during the reaction was 20 ml / min. As a result, 0.71 g (3.3 mmol) of diphenyl carbonate was produced (yield: 47.1%).

Example 3 10 m inner diameter equipped with temperature measuring insertion tube and gas introduction tube
Quartz beads (3 mmφ) were filled in the upper 5/6 part of a quartz reaction tube having a length of m and a length of 300 mm, and the part filled with quartz beads was heated to 600 ° C. while flowing nitrogen gas under normal pressure. Next, the reaction was started by vaporizing the melt of diphenyl oxalate under normal pressure and introducing it into the reaction tube (reaction temperature: 600 ° C.). During the reaction, 250 from the top of the reaction tube
While supplying sulfolane at a position of mm at a rate of 20 ml / min, products and the like adhering to the vessel wall were dissolved and collected.
Diphenyl oxalate 0.80g (3.3mmol) 1
After feeding for a period of time to carry out a reaction, an analysis was conducted in the same manner as in Example 1. As a result, 0.34 g (1.6 g) of diphenyl carbonate was obtained.
0 mmol) was produced (yield: 48.5%).

Example 4 Reaction and analysis were carried out in the same manner as in Example 3 except that the quartz bead-filled portion in Example 3 was heated to 700 ° C. (reaction temperature: 700 ° C.). As a result, diphenyl carbonate was less than 0.
15 g (0.71 mmol) had been produced (yield: 2
1.5%).

Example 5 Inner diameter 10 m equipped with temperature measuring insertion tube and gas introduction tube
Quartz beads (3 mmφ) were filled in the upper 5/6 part of a quartz reaction tube having a length of m and a length of 300 mm, and the part filled with quartz beads was heated to 400 ° C. while flowing nitrogen gas under normal pressure. Next, the reaction was started by vaporizing the melt of diphenyl oxalate and introducing it into the reaction tube under normal pressure (reaction temperature: 400 ° C.). During the reaction, sulfolane was supplied to the position 250 mm from the upper part of the reaction tube at a rate of 10 ml / min, and the products and the like adhering to the vessel wall were dissolved and collected.
2.1 g (8.8 mmol) of diphenyl oxalate was added to 2
After supplying for a period of time to carry out the reaction, the same analysis as in Example 1 revealed that diphenyl carbonate was found to be 0.17 g (0.7
9 mmol) had been produced (yield: 9.0%).

Comparative Example 1 Reaction and analysis were carried out in the same manner as in Example 5 except that the quartz bead-filled portion in Example 5 was heated to 300 ° C. (reaction temperature: 300 ° C.). As a result, diphenyl carbonate was slightly produced.

Example 6 A stainless steel reaction tube having an inner diameter of 20 mm and a length of 750 mm having a thermocouple for temperature measurement mounted on its side wall was charged with 30 ml of α-alumina (2 mmφ), and α was supplied under a normal pressure while flowing nitrogen gas. -The alumina filled part was heated to 500 ° C.
Then, under normal pressure, diphenyl oxalate was vaporized and introduced into the reaction tube together with nitrogen gas (100 ml / min) to start the reaction (reaction temperature: 500 ° C.). During the reaction, about 30 ml / m of acetonitrile was added from the bottom of the reaction tube.
While supplying in, the products adhering to the vessel wall were dissolved and collected. 3.5 g of diphenyl oxalate (14.5
(mmol) for 2 hours to carry out the reaction and then analyzed in the same manner as in Example 1 to find that diphenyl carbonate was 1.65.
g (7.7 mmol) was produced (yield: 53.1).
%). The results of Examples 1 to 5 and Comparative Example 1 are shown in Table 1.

[0022]

[Table 1]

Comparative Example 2 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.
18 g (0.84 mmol) had been produced (yield: 4.
1%).

Comparative Example 3 Internal volume 90 having a gas exhaust pipe, a thermometer and a stirrer
In a ml stainless steel reactor, 5.0 g (20.7 mmol) of diphenyl oxalate, 0.5 g (3.8 mmol) of potassium phenolate and 5.0 g of tetrahydrofuran were placed, and the space of the container was replaced with argon gas. After that, the temperature was raised to 100 ° C. Then, under normal pressure, the decarbonylation reaction was carried out by heating in the liquid phase at this temperature for 1.25 hours. After completion of the reaction, the container was cooled to room temperature and analyzed in the same manner as in Example 1, but no production of diphenyl carbonate was observed.

[0025]

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

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiko Sumita 5 1978, Kozagushi, Ube City, Yamaguchi Prefecture 5 1978, Ube Research Co., Ltd. Ube Laboratory (72) Inventor Yoshifumi Yamamoto 5 1978, Kobugushi, Ube, Yamaguchi Prefecture 5 Ube Kosan Ube Institute Co., Ltd. (72) Inventor Tsunemi Sugimoto 5 1978, Ogushi, Ube, Yamaguchi Prefecture Ube Kosan Co., Ltd. Ube Institute Co., Ltd. (72) Toshio Kurato, 5 1978, Ogushi, Ube, Yamaguchi Prefecture 5 Ube Industries Ube Institute Co., Ltd.

Claims (1)

[Claims] 1. A diaryl oxalate at 330 to 800 ° C.
A method for producing a diaryl carbonate, which comprises heating in a gas phase to carry out a decarbonylation reaction.