JP2733036B2 - Method for producing carbonate ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for continuously producing a carbonic acid ester by transesterifying a carboxylic acid ester and a starting carbonic acid ester in the presence of a catalyst.

[0002] The obtained carbonate is an industrially useful compound. For example, diphenyl carbonate, which is a kind of carbonate, is used as a raw material for polycarbonate.

[0003]

2. Description of the Related Art Conventionally, as a method for producing an aromatic carbonate, for example, a method of transesterifying an aliphatic carbonate with an aromatic hydroxy compound or an aromatic carboxylic acid ester is known. In particular, many proposals have been made on a method for producing dimethyl carbonate, which is a kind of aliphatic carbonate, and phenol, which is a kind of aromatic hydroxy compound, to produce diphenyl carbonate via methylphenyl carbonate. I have. As a method for producing diphenyl carbonate, for example, a method using a Lewis acid or a compound generating Lewis acid as a catalyst (Japanese Patent Publication No. 58-485)
No. 37), a method using a titanium compound or an aluminum compound as a catalyst (Japanese Patent Publication No. 59-34170), a method using a lead compound as a catalyst (Japanese Patent Publication No. 64-3181), and a method using an organotin compound as a catalyst. Method used (Japanese Unexamined Patent Publication No.
-48733).

[0004] All of the above-mentioned methods are carried out in a batch system, and while supplying dimethyl carbonate to the reaction system, methanol by-produced is distilled off. For this reason, it has the disadvantage that the reaction time is long and the productivity is poor. Also, a method of adding benzene to the reaction system in order to efficiently remove methanol (Japanese Patent Publication No. 62-8091) is known. However, in this method, when recovering methanol, the recovery operation is complicated, such as extracting water from a mixed solution of benzene and methanol using water. Therefore, even in this method, the productivity cannot be sufficiently improved.

[0005] A method of producing methylphenyl carbonate by using a continuous multistage distillation column and reacting dimethyl carbonate and phenol in the distillation column (JP-A-3-291257) is known. However, this method has a drawback that the conversion of dimethyl carbonate is about 1.6 mol% to 24 mol%, and the productivity is poor. Further, in the method,
Since methylphenyl carbonate is disproportionated to obtain the desired diphenyl carbonate, there is also a disadvantage that the number of steps for obtaining the diphenyl carbonate is greater than in the other methods.

Further, a method for producing diphenyl carbonate by reacting dimethyl carbonate with phenyl acetate (US Pat.
No. 4,533,504) is known. In this method, the conversion of dimethyl carbonate is as high as 70 mol% or more. However, since this method is a batch type, it has a disadvantage that productivity is poor.

[0007]

As described above, the above-mentioned conventional production methods have drawbacks such as low conversion or poor efficiency in synthesizing raw materials. Further, in the above-mentioned conventional production method in which dimethyl carbonate and phenol are reacted to produce diphenyl carbonate, there is also a problem that dimethyl carbonate and by-produced methanol are azeotropic, so that separation of both is difficult. doing. Therefore, the above-mentioned conventional production method has a problem that the carbonate ester cannot be produced efficiently.

[0008] Therefore, there is a demand for a method capable of industrially producing a carbonate ester efficiently. That is, the present invention has been made in view of the above conventional problems,
An object of the present invention is to provide a novel production method capable of efficiently and continuously producing a carbonate ester by transesterifying a carboxylic acid ester and a raw material carbonate ester in the presence of a catalyst.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to provide a novel industrial method for producing a carbonate ester. As a result, the carboxylic acid ester and the starting carbonate were converted into an ester in the presence of a catalyst. The present inventors have found that the carbonate can be produced efficiently and continuously by bringing the produced carbonate into a gas-liquid contact while exchanging and continuously extracting the produced carbonate outside the reaction system, thereby completing the present invention. Was.

[0010] That is, the manufacturing method of the carbonic acid ester of the invention of claim 1, wherein, in order to solve the above problems, the general formula ^{(1) R 1 COOR 2 ......} (1) ( wherein, R ¹ represents alkyl R ² represents an alicyclic hydrocarbon group or an arylalkyl group, and R ² represents an aromatic group which may have a substituent) and a carboxylic acid ester represented by the general formula (2): R ³ O —COOR ³ (2) (wherein R ³ represents an alkyl group, an alicyclic hydrocarbon group or an arylalkyl group) while transesterifying with a starting carbonic acid ester in the presence of a catalyst. Gas-liquid contacting to form a carbonic acid represented by the following general formula (3): R ² O—COOR ² (3) (wherein, R ² represents an aromatic group which may have a substituent). It is characterized in that the ester is continuously drawn out of the reaction system.

According to a second aspect of the present invention, there is provided a method for producing a carbonate according to the first aspect of the present invention, wherein R ¹ COOR ^{3 is a by-} product of the ^{first aspect.} (4) wherein R ¹ and R ³ each independently represent an alkyl group, an alicyclic hydrocarbon group or an arylalkyl group; It is characterized by being pulled out.

According to a third aspect of the present invention, there is provided a method for producing a carbonate according to the first or second aspect, wherein the boiling point of the by-produced carboxylic acid ester is reduced. It is characterized by using a carboxylic acid ester having a higher boiling point than that of the carboxylic acid ester.

According to a fourth aspect of the present invention, there is provided a method for producing a carbonate according to the first, second or third aspect of the present invention, wherein the boiling point of the produced carbonate is higher than the boiling point of the carbonate produced. A carboxylic acid ester having a low boiling point is used.

[0014] In order to solve the above-mentioned problems, the method for producing a carbonate according to the present invention is characterized in that:
In the method for producing a carbonic acid ester according to 3 or 4, before gas-liquid contact is performed while transesterification, a part of the carboxylic acid ester and a part of the raw material carbonic acid ester are mixed with each other.
It is characterized by being transesterified in advance.

[0015] In order to solve the above-mentioned problems, the method for producing a carbonate according to the invention according to claim 6 has the following features.
3. The method for producing a carbonate ester according to 3, 4, or 5, wherein gas-liquid contact is performed using a multi-stage distillation column.

[0016] In order to solve the above-mentioned problems, the method for producing a carbonate according to the present invention has the following features.
3. The method for producing a carbonate ester according to 3, 4, or 5, wherein a compound having a higher boiling point among the carboxylic acid ester and the raw material carbonate ester is supplied from the upper portion of the bubble column, and It is characterized in that it is supplied from the lower part of the tower and brought into gas-liquid contact.

In order to solve the above-mentioned problems, the method for producing a carbonate according to the invention described in claim 8 is a method for producing a carbonate according to any one of claims 1 to 6, wherein The transesterification of the starting carbonic acid ester proceeds in the presence of a catalyst at a reaction temperature of 50 ° C. to 350 ° C., a reaction pressure of 100 kg / cm ² or less, and a reaction time of 0.01 to 50 hours, at least 10% of the equilibrium conversion of the transesterification. After that, gas-liquid contact is performed while transesterification is further performed.

According to a ninth aspect of the present invention, there is provided a method for producing a carbonate according to the sixth aspect, wherein the molar ratio between the carboxylic acid ester and the starting carbonic acid ester is reduced. 1: 100 to 100: 1, the multi-stage distillation column was set to a reflux ratio of 0 to 100, and the number of stages was 2 to 100.
It is characterized in that the hold-up amount with respect to the empty column volume of a single-stage or multi-stage distillation column is operated at a volume ratio of 0.005 to 0.75, an operation temperature of 50 to 350 ° C, and an operation pressure of 1 mmHg to 100 kg / cm ² .

Hereinafter, the present invention will be described in detail. The method of manufacturing a carbonic ester according to the present invention, a carboxylic acid ester represented by formula used as a starting material (1) is not particularly limited, wherein the substituent represented by R ¹ It is an alkyl group, an alicyclic hydrocarbon group or an arylalkyl group, and is a compound in which the substituent represented by R ² is an aromatic group. The above aromatic group may have a substituent.

As the carboxylic acid ester represented by the general formula (1), specifically, for example, phenyl acetate,
Each isomer of methylphenyl acetate, each isomer of ethylphenyl acetate, each isomer of chlorophenyl acetate, each isomer of isopropylphenyl acetate, each isomer of paramethoxyphenyl acetate, each isomer of dimethylphenyl acetate, naphthyl acetate And phenyl butyrate, phenyl isobutyrate, phenyl valerate and phenyl valerate, phenyl isovalerate, phenyl hexanoate, phenyl heptanoate, and the like. .

In the method for producing a carbonic acid ester according to the present invention, a by-produced carboxylic acid ester, ie, a by-produced carboxylic acid ester, is used in order to increase the reaction efficiency (equilibrium conversion) by favoring the ester exchange reaction equilibrium on the production system side. The by-product carboxylic acid ester represented by the general formula (4) is continuously extracted out of the reaction system. For this reason, among the compounds exemplified above, carboxylate esters having a higher boiling point than the by-produced carboxylic acid ester by-produced are more preferable.

In the method for producing a carbonic acid ester according to the present invention, the raw material carbonic acid ester represented by the general formula (2) used as a raw material is not particularly limited, but is represented by R ³ in the formula. A compound in which a substituent is an alkyl group, an alicyclic hydrocarbon group, or an arylalkyl group.

Examples of the starting carbonic acid ester represented by the general formula (2) include, for example, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, each isomer of dibutyl carbonate, carbonate Each isomer of dipentyl, each isomer of dihexyl carbonate, each isomer of diheptyl carbonate, each isomer of dioctyl carbonate, each isomer of dinonyl carbonate, each isomer of didecyl carbonate, dicyclohexyl carbonate, dibenzyl carbonate, diphenethyl carbonate Each isomer, each isomer of di (methylbenzyl) carbonate and the like can be mentioned. These starting carbonic acid esters may be appropriately mixed and used.
Among the compounds exemplified above, dimethyl carbonate is preferred from an industrial viewpoint.

In order to continuously extract the by-product carboxylic acid ester out of the reaction system, it is preferable to use a carboxylic acid ester having a boiling point higher than that of the by-product carboxylic acid ester. As a combination of such a carboxylic acid ester and a raw material carbonate, for example, when the substituent R ² of the carboxylic acid ester is a phenyl group,
When the substituent R ³ of the starting carbonic acid ester is linear, a compound having 7 or less carbon atoms corresponds to the substituent R ³ .

In order to continuously extract the produced carbonate ester out of the reaction system, it is preferable to use a carboxylic acid ester having a boiling point lower than that of the carbonate ester. Examples of such a carboxylic acid ester include, for example,
When the substituent R ¹ is linear, it corresponds to a compound having 7 or less carbon atoms.

Further, it is preferable that the difference between the boiling points of the carboxylic acid ester and the carbonate is relatively large so that the formed carbonate and the carboxylate can be easily separated. In order to increase the equilibrium conversion of the starting carbonic acid ester, the difference in boiling point between the carboxylic acid ester and the starting carbonic acid ester is preferably relatively small, and the difference in boiling point between the carboxylic acid ester and the by-produced carboxylic acid ester is preferred. Is preferably relatively large.

The gas-liquid contacting reactor used for gas-liquid contact while transesterifying the carboxylic acid ester and the starting carbonic acid ester is not particularly limited.
The gas-liquid contact type reactor has a structure in which a gas phase portion is present in the reactor and a generated low-boiling component can be continuously separated and removed from the gas phase portion, that is, a so-called reactive distillation is performed. Any structure can be used. In particular, a continuous multi-stage distillation column or a bubble column in which a higher-boiling material is supplied from the upper portion of the reactor and a lower-boiling material is supplied from the lower portion of the reactor can be suitably used.

As the continuous multistage distillation column, a distillation column having two or more stages excluding the top (top) and the bottom (bottom) is preferable. Such distillation columns include, for example, packed columns filled with packing materials such as Raschig rings, pole rings, interlock saddles, Dickson packings, McMahon packings, sludge packings; trays such as bubble bell trays, sieve trays, valve trays and the like. A commonly used distillation column such as a plate column using (plate plate) can be used. A combined distillation column having both a tray and a packed bed can also be used. Further, a plurality of multi-stage distillation columns may be used in combination. The above-mentioned number of plates indicates the number of plates in a plate tower, and the theoretical number of plates in a packed column.

The above-mentioned bubble column is preferably a bubble column in which a distributor such as a perforated plate or a porous plate is provided at a gas introduction portion at a lower portion of the reactor in order to efficiently perform gas-liquid contact. Also,
In the bubble column, the packing material may be slowly filled,
A gas redistributor may be provided, and a step may be provided to prevent backmixing of the liquid. Furthermore, a distillation column can be provided above the bubble column to improve the efficiency of gas-liquid separation.

Further, a plurality of the multi-stage distillation towers and the bubble towers may be connected. Thereby, the reaction efficiency can be further improved.

In the method for producing a carbonate according to the present invention, the carboxylic ester and the starting carbonate are transesterified in the presence of a catalyst. Examples of the catalyst include mineral acids such as sulfuric acid; sulfonic acids such as paratoluenesulfonic acid; solid acids such as ion exchange resins and zeolites;
Bases such as sodium hydroxide; metal alkoxides such as titanium tetraisopropoxide and zirconium (IV) isopropoxide; Lewis acids such as aluminum chloride and titanium tetrachloride; and compounds generating Lewis acids; phenoxylead, phenoxytitanium and the like Lead oxides; lead salts such as lead carbonate; zirconium (IV) acetylacetonate, bis (acetylacetonato) copper (II), zinc (II) acetylacetonate, lithium acetylacetonate, etc. Metal acetylacetonate complexes; organotin compounds such as dibutyltin oxide; titanosilicate; metal-substituted aluminum phosphate; Among the above-mentioned catalysts, weak acids and weak bases are more preferred because the selectivity of carbonate ester is improved.

When a solid heterogeneous catalyst is used, the catalyst may be held inside the reactor and the reaction solution may be contacted. When a packed column or a combined distillation column is used as the reactor, a solid catalyst can be packed instead of part or all of the packed material packed in the column.

When a homogeneous catalyst is used, a mixed solution of the catalyst is supplied into the reactor. For example, when a distillation column is used as the reactor, the catalyst can be supplied as a mixture with one or both of the carboxylic acid ester and the starting carbonic acid ester. Alternatively, the solution in which the catalyst is mixed may be supplied to the supply stage of the carboxylic acid ester or the raw material carbonate ester in the distillation column, or may be supplied to a stage different from the supply stage. However, in the distillation column, as the region (stage) where the catalyst is present is larger, the frequency of contact between the reaction solution and the catalyst is increased, and the reaction efficiency is improved.
For this reason, it is preferable to supply the catalyst to the upper stage of the distillation column as much as possible. Further, for example, when a bubble column is used as a reactor, the catalyst can be mixed with a raw material having a higher boiling point and supplied from above the bubble column. Alternatively, the reaction solution may be brought into contact with the catalyst held inside the bubble column.

When a homogeneous catalyst is used, the lower limit of the catalyst concentration is 0.1 ppm, preferably 1 ppm, more preferably 10 ppm, based on the total amount of the carboxylic acid ester and the starting carbonic acid ester, that is, the starting material. The upper limit is the amount that is dissolved in the reaction solution inside the reactor in a saturated state, and is about 10% by weight, preferably 5% by weight, and more preferably 3% by weight.

The method of supplying the raw materials to the reactor is not particularly limited, and a mixture obtained by mixing the carboxylic acid ester and the raw material carbonic acid ester may be continuously supplied. The raw material carbonate ester may be supplied separately and continuously. The carboxylic acid ester and the starting carbonic acid ester may be supplied in a liquid state, in a gaseous state, or in a gas-liquid mixed state. However, it is preferable that the stage for supplying the higher-boiling material is higher than the stage for supplying the lower-boiling material so that the two can be smoothly contacted in the reactor. The high-boiling material may contain a part of the low-boiling material,
The low-boiling material may include a part of the high-boiling material.

The molar ratio between the carboxylic acid ester and the starting carbonic acid ester depends on the type and amount of the catalyst used, the reaction conditions and the like, but is preferably in the range of 1: 100 to 100: 1, more preferably 1:20 to 100: 1. It is more preferably in the range of 20: 1, and 1:10 to
More preferably, it is in the range of 10: 1. Incidentally, the carboxylic acid ester, the raw material when synthesizing the carboxylic acid ester,
That is, unreacted substances may be mixed. Examples of the unreacted product include an aliphatic carboxylic acid ester and an aromatic hydroxy compound. However, when unreacted substances are mixed in the carboxylic acid ester, the content of the carboxylic acid ester in the mixture is preferably 10 mol% or more, and more preferably 20 mol% in order to efficiently produce the carbonate ester.
The above is more preferable, and 30 mol% or more is further preferable.

When operating the above reactor, factors that determine the operating conditions include, for example, operating temperature, operating pressure,
Retention time of the liquid, and the amount of hold-up of the liquid, and the like.Moreover, when the reactor is a distillation column, the number of stages,
Reflux ratio and the like.

The operating temperature depends on the type of the carboxylic acid ester and the starting carbonic acid ester, the type and amount of the catalyst, and other conditions (factors), but is preferably in the range of 50 ° C. to 350 ° C.
The temperature is more preferably in the range of 100C to 280C. The operating pressure may be any of reduced pressure, normal pressure, and pressurized pressure. In addition, although it depends on the type of the carboxylic acid ester and the starting carbonic acid ester, the type and amount of the catalyst, and other conditions (factors), it is approximately the same. 1mmHg ~
Preferably in the range of 100 kg / cm ^2, in the range of 5mmHg~50kg / cm ² is more preferable.

The hold-up amount and the number of stages are closely related to the reaction time, that is, the residence time. That is, to increase the equilibrium conversion, it is necessary to lengthen the residence time to a certain extent, and to extend the residence time, it is necessary to increase the hold-up amount or increase the number of stages.
Of these, it is preferable to increase the hold-up amount, but if it is increased to a certain degree or more, flooding occurs. For this reason, the hold-up amount with respect to the empty column volume (volume) of the reactor is preferably in the range of 0.005 to 0.75, more preferably in the range of 0.01 to 0.5 by volume ratio. When the number of stages is increased, the number of stages is preferably about 2 to 100, taking into account the cost and height restrictions in manufacturing the reactor, utility costs, fixed costs, and the like. When the number of stages is increased, the efficiency of gas-liquid separation is improved when the difference in boiling point between the carboxylic acid ester and the by-produced carboxylic acid ester is relatively small.

The reflux ratio is preferably in the range of 0 to 100,
The range is more preferably from 0 to 50, and even more preferably from 0.1 to 25. When the difference in boiling point between the carboxylic acid ester and the by-produced carboxylic acid ester is relatively small, the reflux ratio is preferably set to a relatively large value in order to allow the reaction to proceed sufficiently.

When a homogeneous catalyst is used, for example, after completion of the reaction, the homogeneous catalyst may be separated and recovered from the reaction solution by using a known method such as distillation. After removing the catalyst, the carbonate represented by the general formula (3) can be easily isolated by using a known method such as distillation, extraction, and recrystallization.

In the method for producing a carbonate according to the present invention, a solvent may be added to the reaction system, that is, the reaction solution, if necessary. Examples of the solvent added for facilitating the reaction operation include compounds inert to the above reaction system, for example, ethers, aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons and the like. Further, in order to easily remove the by-produced carboxylic acid ester from the reaction system, a gas (nitrogen gas or the like) inert to the reaction system can be introduced from the lower part of the reactor.

When the boiling point of the starting carbonic acid ester is relatively low, it is preferable to carry out the transesterification reaction by combining the flow-type reactor and the gas-liquid contact type reactor. That is, first, a transesterification reaction is advanced to some extent in advance using a flow-through reactor, and a considerable amount of the raw material carbonate is converted into carbonate. Next, this reaction solution is supplied to a gas-liquid contact reactor, and gas-liquid contact is performed while the transesterification reaction is further advanced, that is, reactive distillation is performed to continuously remove the by-product carboxylic acid ester from the reaction system. Pull out. This makes it difficult for the starting carbonate to be extracted from the reaction system, so that the reaction efficiency can be further improved.

The operating conditions of the flow reactor depend on the type of the carboxylic acid ester and the starting carbonic acid ester, the type and amount of the catalyst, and other conditions (factors).
The temperature is preferably in the range of -350 ° C, more preferably in the range of 100-280 ° C. The reaction pressure is usually equal to or higher than the atmospheric pressure at the reaction temperature, but may be equal to or higher than the vapor pressure of the reaction solution.
100 kg / cm ² or less is suitable. The reaction time depends on the type and amount of the catalyst, the reaction temperature and the like, but is preferably in the range of 0.01 to 50 hours, more preferably in the range of 0.1 to 20 hours. And it is preferable that the conversion of the carboxylic acid ester or the raw material carbonate is close to the equilibrium conversion of the transesterification reaction. That is, in the flow-through reactor, it is preferable that the transesterification reaction is allowed to proceed until a substantially equilibrium state is reached. However, in order for the transesterification reaction to proceed until the state is substantially equilibrium, the reaction time needs to be extended to some extent. Therefore, in order to efficiently produce a carbonate ester, in a flow-through reactor, if the equilibrium conversion of the transesterification reaction is advanced by 10% or more, more preferably 20% or more, and still more preferably 40% or more. Good.

Next, a method for continuously producing the carbonate represented by the general formula (3) by subjecting the above carboxylate and the starting carbonate to gas-liquid contact while transesterifying in the presence of a catalyst to produce the carbonate represented by the general formula (3). This will be described below. First, an example of a method for producing a carbonate ester using a reactor having a multi-stage distillation column as a reactor will be described with reference to FIG. The reaction device is not limited to the configuration shown in FIG. In the following description, a case where the boiling point of the carboxylic acid ester is higher than the boiling point of the raw material carbonate ester will be described as an example.

As shown in FIG. 1, the above-mentioned reaction apparatus comprises a continuous multi-stage distillation column 1 as a reactor, preheaters 2.3, a reboiler 4, a condenser 5, a pump 6, and the like. .

The continuous multi-stage distillation column 1 is brought into gas-liquid contact while transesterifying the carboxylic acid ester with the starting carbonic acid ester. The continuous multi-stage distillation column 1 is connected to the preheater 2 via a raw material supply pipe 8 and connected to the preheater 3 via a raw material supply pipe 10. The bottom of the continuous multistage distillation column 1 is connected to the reboiler 4 via conduits 11 and 12. Furthermore, the top of the continuous multistage distillation column 1
It is connected to the condenser 5 via a conduit 13. In the continuous multistage distillation column 1, the raw material supply pipe 8 is connected to an upper stage than the raw material supply pipe 10.

The preheater 2 preheats a mixture (hereinafter simply referred to as a carboxylate for convenience of explanation) composed of a raw material containing a larger amount of a carboxylate and a catalyst. The preheater 2 is connected to a raw material tank (not shown) via a raw material introduction pipe 7, and connected to the continuous multi-stage distillation column 1 via a raw material supply pipe 8.

The preheater 3 is configured to preheat a raw material containing a larger amount of the raw material carbonate (hereinafter simply referred to as the raw material carbonate for convenience of explanation). Preheater 3
The raw material tank is connected to another raw material tank (not shown) via a raw material introduction pipe 9, and connected to the continuous multistage distillation column 1 via a raw material supply pipe 10.

The reboiler 4 is connected to the bottom of the continuous multi-stage distillation column 1 via conduits 11 and 12. The reboiler 4 heats the bottom liquid withdrawn through the conduit 11,
It is returned to the bottom of the column through a conduit 12. That is, reboiler 4
Heats and circulates the bottom liquid. The conduit 11 is branched so that a part of the bottom liquid can be continuously withdrawn as a bottom liquid outside the reaction system.

The condenser 5 condenses and liquefies the distillate from the continuous multistage distillation column 1. The condenser 5 is connected to the top of the continuous multi-stage distillation column 1 via a conduit 13 and to the pump 6 via a conduit 14. The condenser 5 is provided with an adjusting pipe 15 having a pressure adjusting valve 16. The conduit 14 is branched so that a part of the distillate can be continuously drawn out of the reaction system.

The pump 6 refluxes the distillate to the continuous multistage distillation column 1 at a predetermined reflux ratio. The pump 6 is connected to the condenser 5 via a conduit 14 and to the top of the continuous multi-stage distillation column 1 via a conduit 17.

Next, an example of a method for producing a carbonate ester using the reactor having the above-described structure will be described.

First, the carboxylic acid ester is continuously supplied from the raw material tank to the continuous multistage distillation column 1 through the raw material introduction pipe 7, the preheater 2, and the raw material supply pipe 8, and from another raw material tank. The raw material carbonate is continuously supplied to the continuous multistage distillation column 1 via the raw material introduction pipe 9, the preheater 3, and the raw material supply pipe 10. The carboxylic acid ester and the raw material carbonate supplied to the continuous multistage distillation column 1 are as follows:
Gas-liquid contact, that is, reactive distillation is performed while transesterification is performed in the presence of a catalyst.

The resulting bottom liquid containing the carbonate represented by the general formula (3) is supplied to the continuous multi-stage distillation column 1.
Continuously extracted from A part of the bottom liquid is heated by the reboiler 4 and returned to the bottom of the continuous multi-stage distillation column 1, and the remaining bottom liquid is continuously withdrawn as a bottom liquid outside the reaction system. That is, the target carbonic acid ester is continuously taken out of the reaction system as a bottom liquid.

On the other hand, the gas containing the by-produced carboxylic acid ester represented by the above general formula (4) is continuously condensed in the condenser 5 to become a distillate. Part of the distillate,
The liquid is returned to the top of the continuous multistage distillation column 1 at a predetermined reflux ratio via the pump 6, and the remaining distillate is continuously drawn out of the reaction system. That is, the by-product carboxylic acid ester as a by-product is continuously taken out of the reaction system as a distillate.

By performing the above-mentioned reaction operations, a carbonate ester can be efficiently and continuously produced.

The reaction apparatus having a multistage distillation column is shown in FIG.
However, the present invention is not limited to the configuration shown in FIG. For example, instead of having a raw material tank and preheaters 2 and 3 (FIG. 1) for separately supplying a carboxylic acid ester and a raw material carbonic acid ester (FIG. 1), the reactor includes It may be configured to include a raw material tank (not shown) for supplying a mixture composed of an ester and a catalyst, a preheater 20, a raw material introduction pipe 21, and a raw material supply pipe 22. in this case,
The raw material supply pipe 22 may be connected to the middle stage of the continuous multi-stage distillation column 1.

Next, an example of a method for producing a carbonate using a flow reactor and a reactor having a multi-stage distillation column as a reactor will be described with reference to FIG.
For the sake of convenience, the same reference numerals are given to components having the same functions as the components provided in the reaction apparatus (FIG. 2),
The description is omitted.

As shown in FIG. 3, the above-mentioned reactor comprises a continuous multistage distillation column 1 as a reactor and a flow reactor 3
3, a reboiler 4, a condenser 5, a pump 6, and the like.

The flow reactor 33 and the continuous multistage distillation column 1 carry out transesterification between the carboxylic acid ester and the starting carbonic acid ester. At the bottom of the flow reactor 33, a conduit 3 is provided.
4 are connected. The conduit 34 is connected to a raw material tank (not shown) for supplying a mixture comprising a carboxylic acid ester and a raw material carbonate. A conduit 36 is connected to the upper part of the flow reactor 33. The conduit 36 is connected to the preheater 20. In addition, conduit 3
A pressure adjusting valve 37 is attached to 6. The pressure control valve 37 adjusts the operating pressure of the flow reactor 33 when the operating pressure of the flow reactor 33 and the operating pressure of the continuous multistage distillation column 1 are different from each other.

The continuous multi-stage distillation column 1 is brought into gas-liquid contact while transesterifying the carboxylic acid ester with the starting carbonic acid ester. Other configurations of the reactor are the same as those of the reactor (FIG. 2).

Next, an example of a method for producing a carbonate ester using the reactor having the above-described structure will be described. For the sake of convenience, the description of the same operations as those in the reaction apparatus (FIG. 2) will be simplified.

First, a mixture of a carboxylic acid ester and a raw material carbonic acid ester is continuously supplied to a flow reactor 33 via a conduit 34. When the catalyst is a homogeneous catalyst, the catalyst is continuously supplied to the flow reactor 33 together with the mixture. When the catalyst is a heterogeneous catalyst, the catalyst is held inside the flow reactor 33 and inside the continuous multi-stage distillation column 1. Further, when a solvent is used, the solvent may be used together with the above mixture in a flow reactor 3.
3 may be continuously supplied.

In the flow reactor 33, the transesterification proceeds to a certain extent. Thereafter, the reaction solution in the flow reactor 33 is transferred to the continuous multi-stage distillation column 1 through a conduit 36.
Continuously.

In the continuous multi-stage distillation column 1, the transesterification reaction proceeds further. That is, the carboxylic acid ester and the starting carbonic acid ester supplied to the continuous multi-stage distillation column 1 are subjected to gas-liquid contact, that is, reactive distillation while transesterifying in the presence of a catalyst.

By performing the above-described reaction operations, a carbonate ester can be efficiently and continuously produced.

A reaction apparatus having a multistage distillation column is shown in FIG.
Or is not limited to the configuration shown in FIG.
Various configurations are possible. The reaction device is, for example,
If the activity of the catalyst is not sufficient, or if the residence time of the liquid in the multi-stage distillation column is relatively short, as shown in FIG.
.. May be provided. In this case, the reactor 51
... is to extract a part of the liquid phase inside the continuous multi-stage distillation column 1,
After sufficiently securing the residence time of the liquid phase, the liquid phase is returned to the continuous multi-stage distillation column 1. The number and arrangement positions of the reactors 51 are not particularly limited (FIG. 4 illustrates a continuous multistage distillation column 1 having two reactors 51).

Further, the reaction apparatus is a continuous multi-stage distillation column 1
Instead of having (FIG. 1) and the like, as shown in FIG. 5, a bubble column 61 as a reactor, a distillation column 62 and the like may be used. Hereinafter, a reactor equipped with a bubble column will be described. In addition, for convenience of explanation, the reactor (FIG. 1)
Components having the same functions as the components provided in are provided with the same reference numerals, and description thereof is omitted.

The bubble column 61 is brought into gas-liquid contact while transesterifying the carboxylic acid ester with the starting carbonic acid ester. The bubble column 61 is connected to the preheater 2 via the raw material supply pipe 8, and is connected to the preheater 3 via the raw material supply pipe 10. A conduit 11 is connected to the bottom of the bubble column 61. Furthermore, the top of the bubble column 61 is connected to the conduit 6
It is connected to the distillation column 62 via 3.64. In the bubble column 61, the raw material supply pipe 8 is connected near the top of the tower, and the raw material supply pipe 10 is connected to the middle stage of the tower.
A distributor 65 such as a perforated plate or a porous plate is provided at the tip of the raw material supply pipe 10 on the bubble column 61 side, that is, at a portion inserted into the bubble column 61.

Further, a conduit 66 is connected near the bottom of the bubble column 61. The conduit 66 includes a preheater 67 and introduces a gas inert to the reaction system into the bubble column 61. A distributor 68 such as a perforated plate or a porous plate is provided in a portion of the conduit 66 inserted inside the bubble column 61. The gas promotes separation of the by-product carboxylic acid ester from the reaction solution.

The distillation column 62 separates the by-product carboxylic acid ester from the reaction solution. The distillation column 62 is connected to the bubble column 61 via conduits 63 and 64. Further, the distillation column 62
Is connected to the condenser 5 via a conduit 13. still,
A reaction solution having a high content of by-product carboxylic acid ester is continuously supplied from the bubble column 61 to the distillation column 62 via the conduit 63. On the other hand, the bottoms from the distillation column 62 are returned to the bubble column 61 via the conduit 64. Also, the condenser 5
The distillate from the distillation column 62 is condensed and liquefied.

The preheater 3 preheats the starting carbonic acid ester,
It is designed to be gaseous. The preheater 3 is connected to the bubble column 61 via the raw material supply pipe 10. Further, the conduit 11 can continuously draw the bottom liquid of the bubble column 61 out of the reaction system. Other configurations of the reactor are the same as those of the reactor (FIG. 1).

Next, an example of a method for producing a carbonate ester using the reactor having the above-described structure will be described. For the sake of convenience, the description of the same operations as those in the reaction apparatus (FIG. 1) will be simplified.

First, the carboxylic acid ester is continuously supplied to the bubble column 61 via the raw material supply pipe 8, and the raw carbonic acid ester is continuously supplied to the bubble column 61 via the raw material supply pipe 10. In addition, an inert gas is continuously supplied to the bubble column 61 via the conduit 66. When the catalyst is a homogeneous catalyst, the catalyst is continuously supplied to the bubble column 61 together with the carboxylic acid ester. When the catalyst is a heterogeneous catalyst, the catalyst is held inside the bubble column 61. Further, when a solvent is used, the solvent is
What is necessary is just to supply continuously to the bubble column 61 with the said carboxylic acid ester or raw material carbonate ester.

The carboxylic acid ester and the starting carbonic acid ester supplied to the bubble column 61 are subjected to gas-liquid contact, that is, reactive distillation while transesterifying in the presence of a catalyst. The generated bottom liquid containing the carbonate represented by the general formula (3) is continuously extracted from the bubble column 61. That is, the target carbonic acid ester is continuously taken out of the reaction system as a bottom liquid.

On the other hand, the reaction solution having a high content of by-product carboxylic acid ester is continuously supplied to the distillation column 62. The reaction solution supplied to the distillation column 62 is continuously distilled, and the bottoms are returned to the bubble column 61. The gas containing the by-produced carboxylic acid ester represented by the general formula (4) is continuously condensed in the condenser 5 to become a distillate. That is, the by-product carboxylic acid ester as a by-product is continuously taken out of the reaction system as a distillate.

By performing the above-described reaction operations, a carbonate ester can be efficiently and continuously produced.
When the by-produced carboxylic acid ester is easily separated from the reaction solution, the conduit 66 for introducing gas may be omitted.

The reactor is not limited to the configuration shown in FIGS. 1 to 5, but may have various configurations.

As described above, the method for producing a carbonic acid ester according to the present invention comprises: converting the carboxylic acid ester represented by the general formula (1) and the starting carbonic acid ester represented by the general formula (2) The mixture is brought into gas-liquid contact while transesterification is carried out in the presence of a catalyst, and the resulting carbonate represented by the general formula (3) is continuously extracted out of the reaction system. In the production method according to the present invention, the by-produced carboxylic acid ester represented by the general formula (4) is continuously extracted to the outside of the reaction system.

In the production method according to the present invention, a carboxylic acid ester having a higher boiling point than that of the by-produced carboxylic acid ester is used. Further, in the production method according to the present invention, a carboxylic acid ester having a boiling point lower than that of the produced carbonate ester is used. In the production method according to the present invention, a part of the carboxylic acid ester and a part of the raw material carbonic ester are transesterified in advance before the gas-liquid contact is performed while the transesterification is performed.

Further, in the production method according to the present invention, gas-liquid contact is performed using a multi-stage distillation column. Further, the production method according to the present invention uses a bubble column, and supplies a compound having a higher boiling point from the upper portion of the bubble column and the other compound from the lower portion of the bubble column. And gas-liquid contact.

Further, in the production method according to the present invention, the transesterification of a carboxylic acid ester and a starting carbonic acid ester is carried out in the presence of a catalyst at a reaction temperature of 50 ° C. to 350 ° C. and a reaction pressure of 100 ° C.
After advancing 10% or more of the equilibrium conversion of the transesterification with kg / cm ² or less and a reaction time of 0.01 to 50 hours, the mixture is brought into gas-liquid contact while further transesterifying. Further, in the production method according to the present invention, the molar ratio between the carboxylic acid ester and the starting carbonic acid ester is 1: 100 to 100: 1, and the multistage distillation column is refluxed at 0 to 100, the number of stages is 2 to 100, and the multistage distillation column is multistage. The hold-up amount to the empty column volume of the distillation column is 0.005 by volume ratio.
~ 0.75, operating temperature 50 ℃ ~ 350 ℃, and operating pressure 1mmHg ~
Operate at 100 kg / cm ² .

As a result, the equilibrium conversion can be improved, and the carbonate can be efficiently and continuously produced.

[0085]

According to the above manufacturing method, the general formula ^{(1) R 1 COOR 2 ......} (1) ( wherein, R ¹ represents an alkyl group, an alicyclic hydrocarbon group or an arylalkyl group, R ² Is a carboxylic acid ester represented by the following general formula (2): R ³ O—COOR ³ (2) wherein R ³ is an alkyl group , Which represents an alicyclic hydrocarbon group or an arylalkyl group) in gas-liquid contact while transesterifying in the presence of a catalyst to produce a general formula (3) R ² O-COOR ² ... (3) (wherein, R ² represents an aromatic group which may have a substituent).

As described above, since the carbonate ester is continuously withdrawn to the outside of the reaction system, the equilibrium of the transesterification reaction can be favored on the production system side, and the reaction efficiency (equilibrium conversion) can be improved. . Thereby, a carbonate ester can be efficiently and continuously produced.

[0087]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Example 1 Carbonic esters were continuously produced using the reactor shown in FIG. However, the continuous multi-stage distillation column 1 used was a stainless steel distillation column having a height of 2.5 m and an inner diameter of 20 mm filled with 1.5 mmφ stainless steel Dickson packing as a packing material. Then, the raw material supply pipe 8 is connected to a position 500 mm below the top of the tower, and from the bottom of the tower.
The raw material supply pipe 10 was connected to a position 750 mm above. Further, instead of heating the bottom liquid using the reboiler 4 or the like, the heat required for distillation was supplied by heating the bottom of the continuous multistage distillation column 1 with a heater.

Then, a raw material containing phenyl acetate (carboxylate) as a main component and titanium tetraphenoxide “Ti (OPh) ₄ ” as a catalyst are fed to the continuous multistage distillation column 1 through a raw material supply pipe 8. Was supplied continuously. The flow rate of the supply liquid A per unit time was 50 g / hr.

Further, the raw material supply pipe 1 is connected to the continuous multi-stage distillation column 1.
Through 0, a supply liquid B (partially gaseous), which is a raw material containing diethyl carbonate (raw material carbonate ester) as a main component, was continuously supplied. The flow rate of the supply liquid B per unit time is 50 g /
hr. The above titanium tetraphenoxide was added such that the amount of titanium added to the raw materials (total amount of phenyl acetate and diethyl carbonate) was 500 ppm.

The operating conditions of the continuous multistage distillation column 1 were as follows: the bottom temperature was 200 ° C., the top pressure was 100 mmHg, and the reflux ratio was 2.
Table 1 shows the above reaction conditions, that is, the flow rates and compositions of the feed liquid A and the feed liquid B, and the operating conditions of the continuous multistage distillation column 1.

In the above continuous multistage distillation column 1, phenyl acetate and diethyl carbonate were brought into gas-liquid contact while transesterifying. The bottoms containing the generated diphenyl carbonate (carbonate) and the distillate containing by-product ethyl acetate (by-product carboxylate) and unreacted diethyl carbonate are continuously removed from the reaction system. I took it out. The flow rate of the bottoms per unit time was 36.0 g / hr. The flow rate of the distillate per unit time was 64.0 g / hr.

Then, the composition of the bottom liquid was analyzed. As a result, the yield of diphenyl carbonate when the raw material (total amount of phenyl acetate and diethyl carbonate) was supplied at a flow rate of 1 kg / hr was 322 g / kg · hr. The conversion of phenyl acetate was 91.6 mol%. Table 3 shows the above reaction results, that is, the flow rates of the distillate and the bottoms, the composition of the bottoms, the yield of diphenyl carbonate, and the conversion of phenyl acetate.

Example 2 Phenyl acetate in Example 1 was changed to phenyl propionate (carboxylate), diethyl carbonate was changed to dipropyl carbonate (raw material carbonate), and titanium tetraphenoxide as a catalyst was changed to dibutyl tin. Diphenyl carbonate was continuously produced using the same reactor as in Example 1 except that the oxide was changed to “Bu ₂ SnO”. Table 1 shows the above reaction conditions, that is, the flow rates and compositions of the feed liquid A and the feed liquid B, and the operating conditions of the continuous multistage distillation column 1. The amount of tin added to the raw material (total amount of phenyl propionate and dipropyl carbonate) was 500 p.
pm.

Then, the composition of the bottom liquid was analyzed. As a result, the yield of diphenyl carbonate was 352 g / kg · hr. The conversion of phenyl propionate was 98.9 mol%. Table 3 shows the above reaction results, that is, the flow rates of the distillate and the bottoms, the composition of the bottoms, the yield of diphenyl carbonate, and the conversion of phenyl propionate.

Example 3 Carbonic esters were continuously produced using the reactor shown in FIG. However, the continuous multi-stage distillation column 1 used was a stainless steel distillation column having a height of 1.5 m and an inner diameter of 20 mm filled with 1.5 mmφ stainless steel Dickson packing as a packing material. Then, a raw material supply pipe 22 was connected to a position 500 mm below the top of the tower. Further, instead of heating the bottom liquid using the reboiler 4 or the like, the heat required for distillation was supplied by heating the bottom of the continuous multistage distillation column 1 with a heater.

The flow-type reactor 33 has a length of 100
A stainless steel reactor having an inner diameter of 20 mm and an inner diameter of 20 mm was used.

Then, a feed liquid composed of a raw material containing phenyl acetate and dimethyl carbonate as main components and dibutyltin oxide as a catalyst was continuously supplied to a flow-type reactor 33 via a conduit. The flow rate of the supply liquid per unit time was 120 g / hr. In addition, dibutyltin oxide is
Tin was added to the raw materials (total amount of phenyl acetate and dimethyl carbonate) so as to be 500 ppm.

The operating condition of the flow reactor 33 was that the reaction temperature was 200 ° C. After the transesterification proceeded to some extent in the flow reactor 33, the reaction liquid (partially gaseous) was continuously supplied to the continuous multistage distillation column 1. The flow rate of the supply liquid C per unit time is 120 g / hr. The pressure in the flow reactor 33 was adjusted to 10 kg / cm ² , that is, the vapor pressure of the reaction solution by operating the pressure adjusting valve 37.
Therefore, the reaction liquid in the flow reactor 33 is maintained in a liquid phase state.

The operating conditions of the continuous multi-stage distillation column 1 were as follows: the bottom temperature was 220 ° C., the top pressure was 100 mmHg, and the reflux ratio was 1.
Table 2 shows the above reaction conditions, that is, the flow rate and composition of the feed liquid C, and the operating conditions of the flow reactor 33 and the continuous multistage distillation column 1.

In the above continuous multistage distillation column 1, phenyl acetate and dimethyl carbonate were brought into gas-liquid contact while transesterifying. Then, the bottoms containing the generated diphenyl carbonate (carbonate) and the distillate containing methyl by-product methyl acetate (by-product carboxylic acid ester) and unreacted dimethyl carbonate are continuously removed from the reaction system. I took it out. The flow rate of the bottoms per unit time was 47.2 g / hr. The flow rate of the distillate per unit time was 72.8 g / hr.

Then, the composition of the bottom liquid was analyzed. As a result, the yield of diphenyl carbonate was 390 g / kg · hr. The conversion of phenyl acetate was 99.2 mol%. Table 3 shows the above reaction results, that is, the flow rates of the distillate and the bottoms, the composition of the bottoms, the yield of diphenyl carbonate, and the conversion of phenyl acetate.

Example 4 The same reaction as in Example 3 except that phenyl acetate in Example 3 was changed to phenyl valerate (carboxylate) and dibutyltin oxide as a catalyst was changed to titanium tetraphenoxide. Diphenyl carbonate was continuously produced using the apparatus.
However, phenyl valerate used as a raw material contained methyl valerate and phenol, which were unreacted substances when the phenyl valerate was synthesized. Table 2 shows the above reaction conditions, that is, the flow rate and composition of the feed liquid C, and the operating conditions of the flow reactor 33 and the continuous multistage distillation column 1. The titanium tetraphenoxide was added so that the amount of titanium added to the raw materials (total amount of phenyl valerate and dimethyl carbonate) was 700 ppm.

The composition of the bottoms was analyzed. As a result, the yield of diphenyl carbonate was 243 g / kg · hr. The conversion of phenyl valerate was 99.0 mol%. Table 3 shows the above reaction results, that is, the flow rates of the distillate and the bottoms, the composition of the bottoms, the yield of diphenyl carbonate, and the conversion of phenyl valerate.

Example 5 Carbonic esters were continuously produced using the reactor shown in FIG. However, a stainless steel bubble tower having a height of 2 m and an inner diameter of 20 mm is used as the bubble tower 61.
A filler filled with a 8 mmφ porcelain Raschig ring was used as the filler. Then, the raw material supply pipe 8 was connected near the top of the tower, and the raw material supply pipe 10 was connected to a position 1 m above the bottom of the tower. Further, perforated plates were used as distributors 65 and 68.
Further, as the distillation column 62, a stainless steel distillation column having a height of 500 mm, which was filled with 1.5 mmφ stainless steel Dickson packing as a packing material was used.

Then, a supply liquid A comprising a raw material mainly composed of phenyl acetate and a lead diphenoxide “Pb (OPh) ₂ ” as a catalyst is continuously supplied to the bubble column 61 via a raw material supply pipe 8. Supplied. The flow rate of the supply liquid A per unit time is
It was 60.1 g / hr. Further, a supply liquid B, which is a raw material containing dimethyl carbonate as a main component, was continuously supplied to the bubble column 61 via the raw material supply pipe 10 in a gaseous state. The flow rate of the supply liquid B per unit time was 60.2 g / hr. Further, nitrogen gas was continuously supplied to the bubble column 61 via a conduit 66. The flow rate of the nitrogen gas per unit time was 1 L / hr. The lead diphenoxide was added so that the amount of lead added to the raw materials (total amount of phenyl acetate and dimethyl carbonate) was 1000 ppm.

The other configuration of the reactor was the same as that of the reactor used in Example 1, and diphenyl carbonate was continuously produced. The above reaction conditions, ie,
Table 1 shows the flow rates and compositions of the feed liquid A and the feed liquid B, and the operating conditions of the distillation column 62.

The composition of the bottoms was analyzed. As a result, the yield of diphenyl carbonate was 302 g / kg · hr. The conversion of phenyl acetate was 85.8 mol%. Table 3 shows the above reaction results, that is, the flow rates of the distillate and the bottoms, the composition of the bottoms, the yield of diphenyl carbonate, and the conversion of phenyl acetate.

[0109]

[Table 1]

[0110]

[Table 2]

[0111]

[Table 3]

As is clear from the results of Examples 1 to 5, by carrying out the method according to this example, the reaction efficiency (equilibrium conversion) can be improved.
It turns out that a carbonate ester can be produced efficiently and continuously.

[0113]

As described above, the method for producing a carbonic acid ester according to the present invention is characterized by the following general formula (1): R ¹ COOR ² (1) wherein R ¹ is an alkyl group, an alicyclic hydrocarbon group. Or an arylalkyl group, and R ² represents an aromatic group which may have a substituent) and a carboxylic acid ester represented by the following general formula (2): R ³ O—COOR ³ (2) (Wherein, R ³ represents an alkyl group, an alicyclic hydrocarbon group, or an arylalkyl group). The carbonate represented by the formula (3) R ² O—COOR ² (3) (wherein R ² represents an aromatic group which may have a substituent) is continuously removed from the reaction system. It is a method of extracting.

As described above, since the carbonate ester is continuously extracted out of the reaction system, the transesterification reaction can be more balanced in the production system, and the reaction efficiency (equilibrium conversion) can be improved. . Thereby, there is an effect that the carbonate can be efficiently and continuously produced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a reaction apparatus suitably used in a method for producing a carbonate in one embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of another reaction apparatus suitably used in the method for producing a carbonate in one embodiment of the present invention.

FIG. 3 is a block diagram showing a schematic configuration of still another reaction apparatus suitably used in the method for producing a carbonate in one embodiment of the present invention.

FIG. 4 is a block diagram showing a schematic configuration of still another reaction apparatus suitably used in the method for producing a carbonate in one embodiment of the present invention.

FIG. 5 is a block diagram showing a schematic configuration of still another reaction apparatus suitably used in the method for producing a carbonate according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Continuous multi-stage distillation tower (multi-stage distillation tower) 2.3 Preheater 5 Condenser 8.10 Raw material supply pipe 33 Flow type reactor 61 Bubble tower 62 Distillation tower

Continuation of front page (72) Inventor Hiroshi Yoshida 14-1 Chidoricho, Kawasaki-ku, Kawasaki-shi, Kanagawa Japan Co., Ltd. Inside the Japan Catalyst Function Development Laboratory (56) References JP-A-51-105032 (JP, A) JP-A Sho 56-123948 (JP, A) JP-A-6-116210 (JP, A)

Claims (9)

(57) [Claims] (1) R ¹ COOR ² (1) wherein R ¹ represents an alkyl group, an alicyclic hydrocarbon group or an arylalkyl group, and R ² has a substituent. A carboxylic acid ester represented by the following general formula (2): R ³ O—COOR ³ (2) wherein R ³ is an alkyl group or an alicyclic hydrocarbon Group or arylalkyl group) and gas-liquid contact while transesterifying in the presence of a catalyst to form a general formula (3) R ² O—COOR ² (3) (Wherein, R ² represents an aromatic group which may have a substituent). A process for producing a carbonate, comprising continuously extracting the carbonate represented by the formula: (2) R ¹ COOR ³ (4) wherein R ¹ and R ³ are each independently an alkyl group, an alicyclic hydrocarbon group or an arylalkyl group. 2. The method for producing a carbonate ester according to claim 1, wherein the by-product carboxylic acid ester represented by the formula (1) is continuously extracted out of the reaction system. 3. The method for producing a carbonate according to claim 1, wherein a carboxylic acid ester having a boiling point higher than that of the by-produced carboxylic acid ester is used. 4. The process for producing a carbonate according to claim 1, wherein a carboxylate having a boiling point lower than that of the produced carbonate is used. 5. A part of the carboxylic acid ester and a part of the starting carbonic acid ester are transesterified before the gas-liquid contact is carried out during the transesterification. 5. The method for producing a carbonate according to 3 or 4. 6. The method for producing a carbonate ester according to claim 1, wherein gas-liquid contact is carried out using a multi-stage distillation column. 7. Using a bubble column, a compound having a higher boiling point among the carboxylic acid ester and the starting carbonic acid ester is supplied from the upper portion of the bubble column, and the other compound is supplied from the lower portion of the bubble column to perform gas-liquid contact. The method for producing a carbonate according to claim 1, 2, 3, 4 or 5. 8. The transesterification of the carboxylic acid ester and the starting carbonic acid ester in the presence of a catalyst at a reaction temperature of 50 ° C. to 3 ° C.
After advancing 10% or more of the equilibrium conversion of the transesterification at 50 ° C., a reaction pressure of 100 kg / cm ² or less, and a reaction time of 0.01 to 50 hours, gas-liquid contact is performed while further transesterifying. A method for producing a carbonic acid ester according to any one of claims 1 to 6. 9. A multistage distillation column having a molar ratio of a carboxylic acid ester to a raw material carbonate ester of 1: 100 to 100: 1, a reflux ratio of 0 to 100, a number of stages of 2 to 100, and an empty column of the multistage distillation column. 0.005 to 0.75 by volume ratio of hold-up amount to volume,
Operating temperature 50 ℃ ~ 350 ℃, operation pressure 1mmHg ~ 100kg / c
method for producing a carbonic ester according to claim 6, characterized in that to operate in m ^2.