JPH0768182B2 - Continuous production method of diaryl carbonate - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a continuous process for producing diaryl carbonates. More specifically, it relates to a method for continuously and efficiently producing a diaryl carbonate using a dialkyl carbonate and an aromatic hydroxy compound as raw materials.

[0002]

2. Description of the Related Art As a method for producing a diaryl carbonate from a dialkyl carbonate and an aromatic hydroxy compound, a method of exchanging two alkyl groups of a dialkyl carbonate with two aromatic groups by using a transesterification reaction between different molecules. Alternatively, or by using an alkylaryl carbonate in which one alkyl group formed in the middle of this reaction is exchanged with one aromatic group, a transesterification reaction between molecules of the same species is carried out to give a diaryl carbonate and a dialkyl carbonate. A method of producing by disproportionation is known.

However, all of these transesterification reactions are equilibrium reactions, and the equilibrium is biased toward the yarn, and the reaction rate is slow. Therefore, the diaryl carbonate is industrially produced by this method. It was very difficult to do. Several proposals have been made to improve this, most of which relate to catalyst development to increase the reaction rate. In the method for producing an alkylaryl carbonate, a diaryl carbonate or a mixture thereof by reacting a dialkyl carbonate with an aromatic hydroxy compound, as such a catalyst, for example, a Lewis acid such as a transition metal halide or a compound that produces a Lewis acid is used. [JP-A-5
1-105032, JP-A-56-123948, JP-A-56-123949 (West German Patent Publication No. 2528412, British Patent No. 1499530, US Patent No. 4182726)), Tin compounds such as organic tin alkoxides and organic tin oxides [JP 54-48733 (West German Patent Publication No. 2736062), JP 54-63023, JP 60-169444 (US Patent 45th
54110), JP-A-60-169445 (US Pat. No. 4,552,704), JP-A-62.
-277345, JP-A 1-265063], salts and alkoxides of alkali metals or alkaline earth metals (JP-A-56-25138),
Lead compounds (JP-A-57-176932), copper,
Complexes of metals such as iron and zirconium (JP-A-57-18)
3745), titanates [JP-A-58-58].
185536 (U.S. Pat. No. 4,104,464)], a mixture of a Lewis acid and a protic acid [JP-A-60-
173016 (US Pat. No. 4,609,501)], compounds such as Sc, Mo, Mn, Bi and Te (JP-A 1-265064), ferric acetate (JP-A 61-172852). ) Etc. have been proposed.

Further, in a method for producing a diaryl carbonate by disproportionating a diaryl carbonate and a dialkyl carbonate by an intermolecular transesterification reaction of an alkylaryl carbonate of the same kind, as such a catalyst, for example, Lewis acid and Lewis acid are used. Possible transition metal compounds [JP-A-51-75044 (West German Patent Publication No. 2552907, US Pat. No. 4045)
No. 464)], a polymeric tin compound [Japanese Patent Laid-Open No.
No. 0-169444 (US Pat. No. 4,554,110)], general formula R—X (═O) OH (wherein X is Sn.
And Ti, and R is selected from a monovalent hydrocarbon group. A compound represented by the formula [JP-A-60-16944]
5 (US Pat. No. 4,552,704)], a mixture of a Lewis acid and a protic acid [JP-A-60-17301].
6 (US Pat. No. 4,609,501)], lead catalyst (JP-A-1-93560), titanium and zirconium compounds (JP-A 1-265062), tin compounds (JP-A 1-265063). ), Sc, M
Compounds such as o, Mn, Bi, Te (Japanese Patent Laid-Open No. 1-265)
No. 064) has been proposed.

However, even in the methods using these various catalysts, the reaction rate cannot be effectively improved, and the diaryl carbonate can be produced with a high selectivity and a high yield in a short reaction time. There wasn't. Another attempt to improve the yield of aromatic carbonates in these reactions is to shift the equilibrium towards the production system as much as possible. As such a method, when an aromatic carbonate such as an alkylaryl carbonate or a diaryl carbonate is produced from a dialkyl carbonate and an aromatic hydroxy compound, for example,
In the reaction of dimethyl carbonate and phenol,
A method of distilling off by-produced methanol together with an azeotropic agent by azeotropic distillation [JP 54-48732 (West German Patent Publication 2736063), JP 61-29].
1545], a method of adsorbing and removing by-produced methanol with a molecular sieve [JP-A-58-1]
No. 85536 (U.S. Pat. No. 4,104,64)] has been proposed.

However, the method disclosed in Japanese Patent Laid-Open No. 54-48732 requires a complicated operation in which heptane, which is used in large amounts as an azeotropic agent, must be separated and recovered from the azeotropic mixture. In addition, also in this method, the yield of aromatic carbonates is only 3.5% even after 45 hours of long reaction with respect to the charged phenol.

Further, according to the method disclosed in Japanese Patent Laid-Open No. 185536/1983, 8 to 10 per 1 g of methanol produced as a by-product.
In addition to requiring a large amount of molecular sieves of g,
A complicated process of desorbing the methanol adsorbed on the molecular sieve is required. Therefore, it is difficult to carry out these methods industrially. In addition, as a preferable reaction system in the above inventions proposed so far,
A device in which towers having distillation and fractionation functions are added to the upper part of the reactor in order to separate the alcohols by-produced by the reaction from the raw materials or products or the coexisting solvents and distill them off. It is also known to use [JP-A-56-123948 (U.S. Pat. No. 4,182,272).
6), JP-A-56-25138, JP-A-60-169444 (US Pat. No. 4,554,110).
Specification), JP-A-60-169445 (US Pat. No. 4,552,704), JP-A-60-1730.
16 (US Pat. No. 4,609,501), JP-A-61-272852, JP-A-61-2915.
45, JP-A-62-277345].

However, in these methods,
In each case, the reaction proceeds only in the reactor where the catalyst is present. And the distillation column part provided in the upper part of the reactor is used only for separating the alcohols produced in the reactor from other components present in the reactor. This is apparent from the detailed description in JP-A-61-291545, which discloses, for example, "Reaction distillation in which a distillation column is usually added to a reactor is used for such a reaction. A reactive distillation method is employed in which methanol having a lower boiling point than the carbonic acid ester produced from the top of the column is distilled off while carrying out the reaction in the reactor at the bottom of the column "(the same publication, page 1, right column, lines 12 to 17). Line). That is, the reactive distillation in these conventional methods is carried out by using an apparatus in which a reaction part and a distillation part exist separately, and only distillation is carried out in the distillation column part and the reaction is not carried out at all. Not not. As described above, in these conventional methods, the reaction is carried out in the liquid phase in the reactor, but the low boiling point alcohol by-produced is not reacted until it is extracted from the liquid phase to the gas phase through the gas-liquid interface. The equilibrium of will shift to the production system side, and the reaction will proceed. However, it is also known that the reaction used in these methods is a tank type, and the reaction is very slow because the gas-liquid interfacial area is as small as the cross-sectional area of the reactor. For example, in Examples of JP-A-61-291545, JP-A-54-48732 and JP-A-54-48733, a batch reaction requires a long time of 8 to 45 hours. Reacting over. In such a method that takes a long time, not only side reactions of the raw materials and intermediates but also side reactions of the produced aromatic carbonates are likely to occur, resulting in a decrease in selectivity. In addition, such a reaction method that takes a long time has poor productivity and is difficult to carry out industrially.

Further, in the conventional method called reactive distillation, which uses an apparatus in which a reaction portion and a distillation portion exist separately, JP-A-62-191545 (page 3, lower left column, line 4) is known. ~ Line 9) "Reactive distillation can be performed either batchwise or continuously, but when dimethyl carbonate is transesterified with phenol, the reaction rate is slow, so The batch method is preferable because it requires a large amount of equipment. ”In fact, in all the examples of the above-mentioned various publications proposed so far, the dialkyl carbonate is used. Both reaction reagents of an aromatic hydroxy compound are initially charged together with a catalyst into a reactor for reaction, or only one of the reaction reagents (usually, an aromatic compound which is a high boiling point compound is used). The Proxy compound) adopts a method of reacting while supplying reactants of the feed while the first reactor together with the catalyst, either a batch system. Therefore, a continuous reaction system in which both reaction reagents are continuously supplied and the product is continuously withdrawn has not been disclosed at all.

[0010]

Under these circumstances, the present inventors have found that the above-mentioned various methods proposed so far do not have the drawbacks and that the dialkyl carbonate and the aromatic compound are An object of the present invention is to provide a method for continuously producing a diaryl carbonate from a hydroxy compound with a high reaction rate and a high selectivity.

[0011]

As a result of earnest studies, the present inventors have surprisingly found that two continuous multi-stage distillation columns are used to carry out reaction and distillation in the presence of a catalyst inside the distillation columns. The present inventors have found that the reactive distillation column system is an excellent method that can easily achieve the above object, and have completed the present invention based on this finding.

That is, the present invention is as follows. 1. When producing a diaryl carbonate from a dialkyl carbonate and an aromatic hydroxy compound, (A) a raw material compound, a dialkyl carbonate and an aromatic hydroxy compound, are continuously fed into a first continuous multi-stage distillation column, and the first continuous multi-stage distillation is performed. While the alkylaryl carbonate formation catalyst and the raw material compound are reacted in the column by contacting each other, the low boiling point component containing the by-produced aliphatic alcohol is continuously extracted in a gaseous state by distillation, while the produced alkylaryl is produced. First step of continuously withdrawing a high boiling point component containing carbonates from a lower part of the tower in a liquid state (B) First containing alkylaryl carbonates
The liquid discharged from the lower part of the continuous multi-stage distillation column is continuously fed into the second continuous multi-stage distillation column, and the alkylaryl carbonate and the diaryl carbonate conversion catalyst are contacted in the second continuous multi-stage distillation column for reaction. While, the low boiling point component containing by-produced dialkyl carbonate is continuously withdrawn in a gaseous state by distillation, and a part or all of it is circulated by supplying it to the first continuous multi-stage distillation column in a gaseous or liquid state. A process for producing a diaryl carbonate, comprising a second step of continuously extracting a high boiling point component containing the produced diaryl carbonate in a liquid state from a lower part of the tower. 2. The method according to claim 1, wherein the alkylaryl carbonate conversion catalyst is a catalyst that can be dissolved in the reaction solution under the reaction conditions and is continuously supplied to the first continuous multi-stage distillation column. 3. The method according to claim 1, wherein the diaryl carbonate conversion catalyst is a catalyst that can be dissolved in the reaction solution under the reaction conditions and is continuously supplied to the second continuous multi-stage distillation column. 4. The alkyl aryl carbonate formation catalyst and / or the diaryl carbonate formation catalyst are solid catalysts and are arranged inside the reactive distillation column.
The method described. 5. When the lower-column withdrawal liquid of the first continuous multi-stage distillation column is supplied to the second continuous multi-stage distillation column, the withdrawal liquid is introduced into the first catalyst separation device, and the low boiling point component containing alkylaryl carbonate and the alkylaryl carbonate formation catalyst are introduced. After separating into a high boiling point component containing it, part or all of the low boiling point component is circulated by supplying it to the second continuous multi-stage distillation column, while a part or all of the high boiling point component containing the catalyst is The method according to claim 2, wherein the method is circulated by feeding to the first continuous multistage distillation column. 6. The liquid extracted from the lower part of the second continuous multi-stage distillation column is introduced into a second catalyst separation device, and separated into a low boiling point component containing a diaryl carbonate and a high boiling point component containing a diaryl carbonate conversion catalyst, and then a high boiling point containing the catalyst. The method according to claim 3, wherein a part or all of the components are circulated by supplying them to the second continuous multi-stage distillation column. 7. When the lower-column withdrawal liquid of the first continuous multi-stage distillation column is supplied to the second continuous multi-stage distillation column, the withdrawal liquid is introduced into the first catalyst separation device, and the low boiling point component containing alkylaryl carbonate and the alkylaryl carbonate formation catalyst are introduced. After separating into a high boiling point component containing it, part or all of the low boiling point component is circulated by supplying it to the second continuous multi-stage distillation column, while a part or all of the high boiling point component containing the catalyst is It is circulated by being supplied to the first continuous multi-stage distillation column, and the lower part of the liquid extracted from the second continuous multi-stage distillation column is guided to a second catalyst separation device, which contains a low boiling point component containing diaryl carbonate and a diaryl carbonate conversion catalyst. After being separated into a high boiling point component, a part or all of the high boiling point component containing the catalyst is supplied to the second continuous multi-stage distillation column for circulation. Claim 2 or 3, characterized in bets
The method described.

The method of the present invention comprises a first reaction step for mainly obtaining an alkylaryl carbonate by a transesterification reaction of an aromatic hydroxy compound and a dialkyl carbonate in a first continuous multi-stage distillation column, and a second continuous multi-stage distillation column. The second reaction step of obtaining a diaryl carbonate by a disproportionation reaction which is a transesterification reaction mainly between the same molecular species of the alkyl aryl carbonate in the above. All of these reactions usually proceed in the liquid phase. The main reaction in the first continuous multi-stage distillation column is, for example, an equilibrium reaction as shown in Chemical formula 1 when an aromatic monohydroxy compound and a symmetrical dialkyl carbonate are used.
The equilibrium is extremely biased toward the yarn.

[0014]

[Chemical 1]

The main reaction in the second continuous multi-stage distillation column is
For example, when an alkylaryl carbonate composed of a monovalent aromatic group Ar is used, the equilibrium reaction as shown in Chemical formula 2 occurs, but the equilibrium is also biased toward the yarn.

[0016]

[Chemical 2]

The method of the present invention allows these reactions to be carried out in the presence of a catalyst in a continuous multistage distillation column, while at the same time
The method is characterized in that the low boiling point product generated by the reaction is separated from the reaction system by distillation, and by this method, aromatic carbonate can be continuously produced with high selectivity and high yield. By such a method, the reaction of the present invention in which the equilibrium is extremely biased toward the original system [eg, the equilibrium constant of the reaction represented by the formula (1) is 10 ^-3 to 10 ^-4
It is completely unexpected that the aromatic carbonate can be continuously produced with a high selectivity and a high yield by proceeding at a high reaction rate.

It is quite surprising that the method of the present invention has a higher reaction rate than the conventional method and can dramatically improve the selectivity and the yield (or productivity), and its exact Although the reason is not clear, the following is presumed based on the result of carrying out the method of the present invention. That is, the reactions of the present invention represented by the above formulas (1) and (2) are all equilibrium reactions, and the equilibria are extremely biased toward the original system. Therefore, in any of the reactions, in order to increase the reaction rate, a by-product which is a low boiling point product generated by the reaction (usually, in the reaction of the formula (1), an aliphatic alcohol, in the reaction of the formula (2), It is necessary to remove the dialkyl carbonate) from the liquid phase in the reaction system as quickly as possible.

However, it has been impossible to increase the reaction rate by a reaction system using a reaction vessel having a distillation column installed in the upper part as described in the above-mentioned various publications showing the prior art. It is not only limited to the reaction vessel where the catalyst is present, but also the gas-liquid interface area for evaporating the low boiling point products produced by the reaction from the liquid in the reaction vessel to the gas phase. Is small.

On the other hand, in the method of the present invention, the catalyst is allowed to exist in a wide range in the first and second continuous multi-stage distillation columns, and the reaction proceeds in a wide area having a very large gas-liquid interface area. Can be made. In this region, the supplied liquid substance to be reacted flows down while reacting while repeating distillation by repeating vapor-liquid contact with vapor rising from below. At this time, the low boiling point product evaporates from the liquid phase to the vapor phase. As a result, each component inside the continuous multi-stage distillation column has a concentration distribution. For example, when the reaction represented by the formula (1) is carried out in the first continuous multi-stage distillation column, the concentration of the alkylaryl carbonate and / or diaryl carbonate, which is usually a high boiling point product, in the liquid is such that the catalyst is present. It has a distribution that gradually increases from the highest stage to the lower part of the column, while the concentration of the aliphatic alcohol, which is a low boiling point product, in the liquid usually decreases gradually from the upper part to the lower part of the column. It has a distribution, and its concentration in the liquid can be made very low near the bottom of the tower. In the vapor phase, the concentration of the aliphatic alcohol gradually increases from the lower part of the column to the upper part of the column.

Further, for example, when the reaction represented by the formula (2) is carried out inside the second continuous multi-stage distillation column, the concentration of diaryl carbonate, which is a high-boiling product, in the liquid is usually the most when the catalyst is present. It has a distribution that gradually increases from the higher stage to the lower part of the column, while the concentration of dialkyl carbonate, which is a low boiling point product, in the liquid usually has a distribution that gradually decreases from the upper part to the lower part of the column. Therefore, it is possible to make the concentration in the liquid very low near the lower part of the tower. In the vapor phase, the concentration of dialkyl carbonate gradually increases from the bottom of the column to the top of the column.

In the method of the present invention, these reactions proceed in the first and second continuous multi-stage distillation columns in this manner. Considering any position in this reaction region, the liquid in the reaction system is considered. As a result of the reaction, the phase is in a state of approaching the equilibrium composition, and it is considered that the vapor phase is also in a state of approaching the vapor-liquid equilibrium state to the liquid phase. Therefore, when the liquid phase stays at this position, the reaction does not proceed any more, but in reality, the liquid phase flows down to make vapor-liquid contact with the vapor phase having a lower boiling point and lower concentration of the reaction product. As a result, the reaction can be further advanced, and the concentration of the high boiling point product, alkylaryl carbonate or diaryl carbonate, in the liquid phase can be further increased.

The conventional method of carrying out the reaction in a reaction kettle having a distillation tower installed above is to proceed the reaction only in the reaction kettle, and the distillation tower simply discharges from the gas-liquid interface in the reaction kettle to the gas phase. It only plays the role of separating the low boiling point product vapor and the low boiling point raw material compound vapor, causing the low boiling point raw material compound to flow down in a liquid state, and returning it to the reaction vessel. Therefore,
It is considered that the reason why the method of the present invention has an excellent effect as compared with the conventional method is mainly due to the following points.
The gas-liquid interfacial area can be made very large as compared with the reaction type using a reaction vessel, and as a result, the mass transfer of the low boiling point product, which is a by-product, to the vapor phase is easy.
The liquid phase of the reaction system in the continuous multi-stage distillation column flows down while reacting while repeating vapor-liquid contact with the vapor rising from below. Therefore, it is possible to increase the reaction rate of the raw material compound in spite of being the continuous method (in the continuous method of continuously extracting the target aromatic carbonates by the conventional reaction method using the reaction vessel, the reaction of the raw material compound is It is difficult to increase the reaction rate, and in fact, no method has been proposed so far to carry out the reaction continuously. In order to increase the reaction rate in this conventional method, it is necessary to carry out the reaction in a batch method for a long time). As the vapor rising in the continuous multi-stage distillation column rises, it rises while repeating liquid-vapor contact with the descending liquid. Therefore, the thermal energy of steam is effectively used.

The dialkyl carbonate used as a raw material compound in the present invention is represented by the general formula 3.

[0025]

[Chemical 3]

(R ¹ and R ² represent an alkyl group, an alicyclic group or an aralkyl group, and R ¹ and R ² may be the same or different, or R ¹ and R ² May be a component constituting a ring.) Such R ¹ ,
Examples of R ² include methyl, ethyl, propyl (each isomer), allyl, butyl (each isomer), butenyl (each isomer), pentyl (each isomer), hexyl (each isomer),
Alkyl group such as heptyl (each isomer), octyl (each isomer), nonyl (each isomer), decyl (each isomer), cyclohexylmethyl; cycloaliphatic such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl Group: benzyl, phenethyl (each isomer),
Examples include aralkyl groups such as phenylpropyl (each isomer), phenylbutyl (each isomer), and methylbenzyl (each isomer).

The alkyl group, alicyclic group and aralkyl group may be substituted with other substituents such as a lower alkyl group, a lower alkoxy group, a cyano group and a halogen atom, or an unsaturated bond may be formed. You may have. Examples of the dialkyl carbonate having R ¹ and R ² include dimethyl carbonate, diethyl carbonate, dipropyl carbonate (each isomer), diaryl carbonate, dibutenyl carbonate (each isomer), butyl carbonate (each isomer). ), Dipentyl carbonate (each isomer), dihexyl carbonate (each isomer), diheptyl carbonate (each isomer), dioctyl carbonate (each isomer), dinonyl carbonate (each isomer), didecyl carbonate (each isomer) body),
Dicyclopentyl carbonate, dicyclohexyl carbonate, dicycloheptyl carbonate, dibenzyl carbonate, diphenethyl carbonate (each isomer), di (phenylpropyl) carbonate (each isomer), di (phenylbutyl) carbonate (each isomer), Di (chlorobenzyl) carbonate (each isomer), Di (methoxybenzyl) carbonate (each isomer), Di (methoxymethyl) carbonate, Di (methoxyethyl) carbonate (each isomer), Di (chloroethyl) carbonate (each) Isomer), di (cyanoethyl) carbonate (each isomer), methyl ethyl carbonate,
Methyl propyl carbonate (various isomers), methyl butyl carbonate (various isomers) ethyl propyl carbonate (various isomers), ethyl butyl carbonate (various isomers), dibenzyl carbonate, ethylene carbonate, propylene carbonate and the like are used.

Among these dialkyl carbonates,
In the present invention, preferably used is a dialkyl carbonate in which each of R ¹ and R ² is an alkyl group having 4 or less carbon atoms, and dimethyl carbonate is particularly preferable. The aromatic hydroxy compound which is a raw material compound used in the present invention is represented by the general formula Ar ¹ OH (4) (Ar ¹ represents an aromatic group), and a hydroxy group is directly attached to the aromatic group. It may be any as long as it is bound.

Examples of such Ar ¹ include phenyl, tolyl (each isomer), xylyl (each isomer), trimethylphenyl (each isomer), tetramethylphenyl (each isomer), ethylphenyl (each isomer). Body), propylphenyl (each isomer), butylphenyl (each isomer),
Phenyl groups and various alkylphenyls such as diethylphenyl (each isomer), methylethylphenyl (each isomer), pentylphenyl (each isomer), hexylphenyl (each isomer), cyclohexenyl (each isomer) Bases.

Methoxyphenyl (each isomer), ethoxyphenyl (each isomer), butoxyphenyl (each isomer)
Various alkoxyphenyl groups such as. Various halogenated phenyl groups such as fluorophenyl (each isomer), chlorophenyl (each isomer), bromophenyl (each isomer), chloro (methylphenyl) (each isomer), dichlorophenyl (each isomer).

Various substituted phenyl groups represented by Chemical formula 4.

[0032]

[Chemical 4]

[However, A is a bond, or -O
A divalent group such as —, —S—, CO—, SO ₂ —, or an alkylene group or a substituted alkylene group represented by Chemical formula 5

[0034]

[Chemical 5]

(Wherein R ⁴ , R ⁵ , R ⁶ and R ⁷ are each a hydrogen atom, a lower alkyl group, a cycloalkyl group, an aryl group or an aralkyl group, and are optionally substituted with a halogen atom or an alkoxy group. Or a cycloalkylene group represented by Chemical formula 6

[0036]

[Chemical 6]

(Wherein k is an integer of 3 to 11, the hydrogen atom may be substituted with a lower alkyl group, an aryl group, a halogen atom, etc.), and the aromatic ring is a lower alkyl group, a lower alkyl group. It may be substituted with a substituent such as an alkoxy group, an ester group, a hydroxyl group, a nitro group, a halogen or a cyano group]. Naphthyl (each isomer),
Naphthyl groups such as methylnaphthyl (each isomer), dimethylnaphthyl (each isomer), chloronaphthyl (each isomer), methoxynaphthyl (each isomer), cyanonaphthyl (each isomer), and various substituted naphthyl groups.

Pyridyl (each isomer), Coumaryl (each isomer), Quinolyl (each isomer), Methylpyridyl (each isomer), Chlorpyridyl (each isomer), Methylcoumarin (each isomer), Methylquinolyl ( And various substituted and unsubstituted heteroaromatic groups such as each isomer).
Examples of such an aromatic hydroxy compound having Ar ¹ include phenol.

Cresol (each isomer), xylenol (each isomer), trimethylphenol (each isomer), tetramethylphenol (each isomer), ethylphenol (each isomer), propylphenol (each isomer), Butylphenol (each isomer), Diethylphenol (each isomer), Methylethylphenol (each isomer), Methylpropylphenol (each isomer), Dipropylphenol (each isomer), Methylbutylphenol (each isomer), Various alkylphenols such as pentylphenol (each isomer), hexylphenol (each isomer), cyclohexylphenol (each isomer); methoxyphenol (each isomer), ethoxyphenol (each isomer)
Various alkoxyphenols such as.

Various substituted phenols represented by Chemical formula 7.

[0041]

[Chemical 7]

(A is as described above) Naphthol (each isomer) and various substituted naphthols.
Heteroaromatic hydroxy compounds such as hydroxypyridine (each isomer), hydroxycoumarin (each isomer), and hydroxyquinoline (each isomer) are used.

Aromatic dihydroxy compounds having two hydroxyl groups, such as hydroquinone, resorcin, catechol, dihydroxynaphthalene, dihydroxyanthracene and their alkyl-substituted dihydroxy compounds. An aromatic dihydroxy compound represented by Chemical formula 8.

[0044]

[Chemical 8]

(However, A is as described above, and the aromatic ring may be substituted with a substituent such as a lower alkyl group, a lower alkoxy group, an ester group, a nitro group and a cyano group.) And the like can also be used. it can. Among these aromatic hydroxy compounds, those which are preferably used in the present invention are aromatic monohydroxy compounds in which Ar ¹ is an aromatic group having 6 to 10 carbon atoms, and phenol is particularly preferable.

The alkylaryl carbonate referred to in the present invention is a dialkyl carbonate represented by the above formula (1) in which one alkyl group is substituted with an aromatic group, and is represented by the general formula 9. Is.

[0047]

[Chemical 9]

(R ³ is R ¹ or R ² , R ¹ , R 2
² , Ar ¹ is as described above), and the aromatic hydroxy compound (Ar ¹ OH) represented by the formula (4) has two hydroxyl groups. In the case of, those represented by the general formula 10 are also included in the alkylaryl carbonate.

[0049]

[Chemical 10]

(R ³ is as described above, Ar ² represents a divalent aromatic group having the same skeleton as Ar ^1, and m represents 1 or 2.) As such an alkylaryl carbonate, For example, methyl phenyl carbonate, ethyl phenyl carbonate, propyl phenyl carbonate (each isomer), allyl phenyl carbonate, butyl phenyl carbonate (each isomer), pentyl phenyl carbonate (each isomer), hexyl phenyl carbonate (each isomer), Heptyl phenyl carbonate (each isomer), octyl tril carbonate (each isomer), nonyl (ethylphenyl) carbonate (each isomer), decyl (butylphenyl) carbonate (each isomer), methyltolyl carbonate (each isomer) , Ethyl Tolyl Carbonay (Each isomer), propyl tolyl carbonate (each isomer), butyl tolyl carbonate (each isomer), allyl tolyl carbonate (each isomer), methyl xylyl carbonate (each isomer), methyl (trimethylphenyl) carbonate ( Each isomer),
Methyl (chlorophenyl) carbonate (each isomer),
Methyl (nitrophenyl) carbonate (each isomer),
Methyl (methoxyphenyl) carbonate (each isomer), methyl cumyl carbonate (each isomer), methyl (naphthyl) carbonate (each isomer), methyl (pyridyl) carbonate (each isomer), ethyl cumyl carbonate (each isomer) Isomer), methyl (benzoylphenyl) carbonate (each isomer), ethyl xylyl carbonate (each isomer), benzyl xylyl carbonate, methyl (hydroxyphenyl) carbonate (each isomer), ethyl (hydroxyphenyl) carbonate ( Each isomer), methoxycarbonyloxybiphenyl (each isomer), methyl (hydroxyphenyl) carbonate (each isomer), methyl 2- (hydroxyphenyl) propylphenyl carbonate (each isomer), ethyl 2- (hydroxyphenyl) Propylph Alkylsulfonyl carbonate (isomers) and the like.

The diaryl carbonate as used in the present invention is a dialkyl carbonate in which two alkyl groups are substituted by an aromatic group, and has the general formula 11
Is represented by.

[0052]

[Chemical 11]

(Ar ¹ .Ar ² are as described above, Ar ³
Represents an aromatic group similar to that described for Ar ¹ , and Ar
⁴ represents the same divalent aromatic group as described for Ar ² . Examples of such a diaryl carbonate include diphenyl carbonate, ditolyl carbonate (various isomers), phenyltolyl carbonate (various isomers), di (ethylphenyl) carbonate (various isomers), phenyl (ethylphenyl) carbonate. (Various isomers), dinaphthyl carbonate (various isomers), di (hydroxyphenyl) carbonate (various isomers),
Examples include di [2- (hydroxyphenylpropyl) phenyl] carbonate (various isomers).

In the first step of the present invention, the aliphatic alcohol produced is withdrawn in a gaseous state, and the alkylaryl carbonate produced is withdrawn in liquid form from the lower part of the column. Therefore, in the present invention, the dialkyl carbonate and the aromatic hydroxy compound are used in a combination such that the boiling point of the produced aliphatic alcohol is lower than the boiling point of the product alkylaryl carbonate. Such a preferable combination includes R ¹ and R ^{2 in the} dialkyl carbonate represented by the formula (3) and the aromatic hydroxy compound represented by the formula (4) or the formula (6).
Is an alkyl group having 1 to 4 carbon atoms, and Ar ¹ or Ar ²
Is an aromatic group having 6 to 10 carbon atoms.
A particularly preferred combination is when the dialkyl carbonate is dimethyl carbonate and the aromatic hydroxy compound is phenol. In this case, the alkyl aryl carbonate produced is methyl phenyl carbonate and the diaryl carbonate is diphenyl carbonate.

The catalyst used in the first reaction step of the present invention is an alkyl aryl carbonate formation catalyst, and any catalyst can be used as long as it can produce an alkyl aryl carbonate by the reaction of a dialkyl carbonate and an aromatic hydroxy compound. But it can be used. For example, (lead compound) lead oxides such as PbO, PbO ₂ , Pb ₃ O ₄ ; lead sulfides such as PbS, Pb ₂ S; Pb (O
H) ₂ , Pb ₂ O ₂ (OH) ₂ and other lead hydroxides; Na
₂ PbO, K ₂ PbO ₂ , NaHPbO ₂ , KHPbO
Zinc salts such as ₂ ; Na ₂ PbO ₃ , Na ₂ H ₂ Pb
O ₄ , K ₂ PbO ₃ , K ₂ [Pb (OH) ₆ ], K ₄ P
bO _4, Ca ₂ PbO _4, lead acid salts such as CaPbO _3; PbCO _3, lead carbonates such as 2PbCO ₃ · Pb (OH) ₂ and its basic salts; PbCl _2, PbBr
₂ , PbI ₂ , 3PbBr ₂ · 2PbO, PbCl ₂ ·
Lead halides such as Pb (OH) ₂ ; PbSO ₄ , P
_{bO · PbSO 4, 2PbO · PbSO} 4, 3PbO ·
PbSO ₄ , 4PbO · PbSO ₄ , Pb (N
O _{2) 2,} inorganic acid salts of lead such as _{2PbO · PbHPO 3; Pb (OCOCH} 3) 2, Pb (OCOCH 3) 4,
Lead salts of organic acids such as Pb (OCOCH ₃ ) ₂ · PbO · 3H ₂ O and their carbonates and basic salts; Bu ₄ Pb,
Ph ₄ Pb, Bu ₃ PbCl, Ph ₃ PbBr, Ph ₃
Pb (or Ph ₆ Pb ₂ ), Bu ₃ PbOH, Ph ₃
Organic lead compounds such as PhO (Bu represents a butyl group, Ph represents a phenyl group); Pb (OCH ₃ ) ₂ , (CH ₃ O)
Pb (OPh), Pb (OPh) ₂ and other alkoxy lead compounds, aryloxy lead compounds; Pb-Na, Pb-Ca, P
Lead alloys such as b-Ba, Pb-Sn, Ph-Sb, and Pb-Te; lead minerals such as houenite and senaenite, and hydrates of these lead compounds.

(Copper Compound) CuCl, CuCl ₂ , CuBr, CuB
r ₂ , CuI, CuI ₂ , Cu (OAc) ₂ , Cu (a
cac) ₂ , copper oleate, Bu ₂ Cu, (CH ₃ O)
₂ Cu, AgNO ₃ , AgBr, silver picrate, AgC
₆ H ₆ ClO ₄ , Ag (bulvarene) ₃ NO ₃ , [Au
C≡C—C (CH ₃ ) ₃ ] _n [Cu (C ₇ H ₈ ) Cl]
A salt of a copper group metal such as ₄ and a body (acac represents an acetylacetone chelate ligand).

(Alkali Metal Complex) Li (acac), LiN (C
₄ H ₉ ) _{2 and} other alkali metal complexes. (Zinc Complex) A zinc complex such as Zn (acac) ₂ . (Cadmium complex) A cadmium complex such as Cd (acac) ₂ .

(Compound of Iron Group Metal) Fe (C ₁₀ H ₈ ) (CO) ₅ , F
e (CO) ₅ , Fe (C ₄ H ₆ ) (CO) ₃ , Co (mesitylene) ₂ (PEt ₂ Ph) ₂ , CoC ₅ F ₆ (C
O) ₇ , Ni-π-C ₅ H ₅ NO, iron group metal complexes such as ferrocene. (Zirconium Complex) A zirconium complex such as Zr (acac) ₄ or zirconocene.

(Lewis Acid Compounds) AlX ₃ , TiX ₃ , TiX ₄ ,
Transition metal compounds that generate Lewis acids and Lewis acids such as VOX ₃ , VX ₅ , ZnX ₂ , FeX ₃ , SnX ₄ (where X is a halogen, acetoxy group, alkoxy group, or aryloxy group). (Organotin compound) (CH ₃ ) ₃ SnOCOCH ₃ ,
_{(C 2 H 5) 3 SnOCOC} 6 H 5, Bu 3 SnOCO
CH ₃ , Ph ₃ SnOCOCH ₃ , Bu ₂ Sn (OCO
_{CH 3) 2, Bu 2 Sn} (OCO 11 H 23) 2, Ph 3 S
nOCH ₃ , (C ₂ H ₅ ) ₃ SnOPh, Bu ₂ Sn
(OCH ₃ ) ₂ , Bu ₂ Sn (OC ₂ H ₅ ) ₂ , Bu ₂
Sn (OPh) ₂ , Ph ₂ Sn (OCH ₃ ) ₂ , (C _{2
H 5) 3 SnOH, Ph 3} SnOH, Bu 2 SnO,
(C ₈ H ₁₇ ) ₂ SnO, Bu ₂ SnCl ₂ , BuSnO
Organotin compounds such as (OH).

(Inorganic oxide) silica, alumina, titania, silica-titania, zinc oxide, zirconium oxide, gallium oxide,
Solid catalysts such as zeolites and rare earth oxides; those obtained by modifying the surface acid points of these solid catalysts by a method such as silylation are used. These catalysts may or may not be soluble in the reaction solution under the reaction conditions. Further, these catalysts can be used by mixing with a compound or carrier which is inert to the reaction, or by being supported on them.

Of course, these catalyst components may be reacted with organic compounds existing in the reaction system, such as aliphatic alcohols, aromatic hydroxy compounds, alkylaryl carbonates, diaryl carbonates and dialkyl carbonates. It may be present, or may be heat-treated with a raw material or a product prior to the reaction.

Among these catalysts, lead oxides such as PbO, PbO ₂ and Pb ₃ O ₄ ; lead hydroxides such as Pb (OH) ₂ and Pb ₂ O ₂ (OH) ₂ are particularly preferably used. PbCO ₃ , 2PbCO ₃ · Pb (OH) ₂ and other lead carbonates and basic salts thereof; Pb (OC
H ₃ ) ₂ , (CH ₃ O) Pb (OPh), Pb (OP
h) lead compounds such as alkoxy lead compounds such as ₂ and aryloxy lead compounds, which are reacted with an organic compound present in the reaction system, or these lead compounds prior to the reaction. Those which are heat-treated with raw materials or products are also preferably used.

The catalyst used in the second step of the present invention is a diaryl carbonate formation catalyst, and any catalyst can be used as long as it can produce diaryl carbonates from alkyl aryl carbonates.
Examples of such a catalyst include the catalyst used in the first step of the present invention. The catalyst used in the second step may be the same as or different from the catalyst used in the first step.

The continuous multi-stage distillation column used in the first step and the second step of the present invention is a distillation column having a multi-stage distillation with two or more stages, and if continuous distillation is possible. Any number may be used (the number of distillation columns in the present invention represents the number of trays in the case of a plate column, and the theoretical number of columns in a packed column type and other distillation columns). .).

Examples of such a continuous multi-stage distillation column include a tray column type using trays such as bubble tray, perforated plate tray, valve tray, countercurrent tray, Raschig ring, Lessing ring, Pall ring, Beruru saddle,
Any type that is normally used as a continuous multi-stage distillation column, such as a packed column type filled with various packings such as Interlocks saddle, Dickson packing, McMahon packing, Helipack, Sulzer packing, Melapak, etc. Can be used. Further, a plate-packing mixing column type distillation column having both a plate part and a part filled with a packing material is also preferably used.
When a solid catalyst is used, a packed column distillation column in which the solid catalyst is a part or all of the packing is also preferably used. In the first step of the present invention, the catalyst may be present in the reaction system by continuously supplying the catalyst to the first continuous multi-stage distillation column, or the solid catalyst may be arranged in the first continuous multi-stage distillation column. By doing so, a catalyst can be present in the reaction system. When the catalyst is continuously supplied to the first continuous multi-stage distillation column, it may be supplied simultaneously with the raw materials,
You may supply to a position different from a raw material. Further, the catalyst may be supplied to any position other than the tower bottom. However, since the reaction actually takes place in the first continuous multi-stage distillation column below the catalyst supply position, it is preferable to supply the catalyst to the region between the tower top and the raw material supply position. When a solid catalyst is used, the required amount of the catalyst can be packed in any position in the first continuous multi-stage distillation column. In the area where no catalyst exists in the first continuous multi-stage distillation column, it functions only as a normal distillation column such as concentration of reaction by-products.

In the present invention, the raw material can be supplied to any stage of the first continuous multi-stage distillation column from any number of inlets.
The raw material is liquid or steam or a mixture of liquid and steam.
It is supplied to a continuous multi-stage distillation column. Further, in addition to supplying the raw material as a liquid or vapor to the first continuous multi-stage distillation column, additionally supplying the raw material vapor to the lower part of the first continuous multi-stage distillation column,
It is a preferable method because it has the effect of substantially lowering the concentration of the aliphatic alcohol in the vapor phase rising in the first continuous multi-stage distillation column.

In the first step of the present invention, the by-produced aliphatic alcohol is extracted in a gaseous state. The gaseous extract may be an aliphatic alcohol alone, a mixture with a dialkyl carbonate or an aromatic hydroxy compound as a raw material, and may contain a small amount of alkylaryl carbonates. The gas outlet of the aliphatic alcohol or the like in the first continuous multi-stage distillation column can be provided at any position other than the bottom of the column, but the concentration of the by-produced aliphatic alcohol in the vapor phase is usually
The higher the tower is, the higher it is. Therefore, it is preferable to provide a gas extraction port between the raw material supply position and the top of the column or at the top of the column, and more preferably at the top of the column.

In the first step of the present invention, the main product, alkylaryl carbonates, is withdrawn in liquid form from the lower part of the first continuous multi-stage distillation column. The liquid extract may be an alkylaryl carbonate alone, a mixture with a dialkyl carbonate or an aromatic hydroxy compound as a raw material, or may contain a small amount of an aliphatic alcohol, and May contain a small amount of diaryl carbonate. When a catalyst that can be dissolved in the reaction solution under the reaction conditions is used, the liquid extract contains the catalyst. The outlet for the liquid containing alkylaryl carbonates in the first continuous multi-stage distillation column is provided at the bottom of the column, particularly preferably at the bottom of the column. In the present invention, the lower part of the column refers to a part between the raw material supply position and the bottom of the column, usually a part near the bottom of the column.

In the first step of the present invention, the reaction product alkylaryl carbonate or diaryl carbonate may be contained in the raw material supplied to the first continuous multi-stage distillation column, but this reaction is a reversible reaction. Therefore, if the concentration of the alkylaryl carbonate or the diaryl carbonate is too high, the reaction rate of the raw material is lowered, which is not preferable. Therefore, the amount of the alkylaryl carbonate and the diaryl carbonate in the raw material is usually preferably 20 mol% or less, more preferably 10 mol% or less with respect to the aromatic hydroxy compound as the raw material.

The amount ratio of the aromatic hydroxy compound and the dialkyl carbonate, which are the reaction raw materials in the first step, may vary depending on the reaction conditions, but is usually expressed by the molar ratio of the aromatic hydroxy compound to the dialkyl carbonate in the feed material. , 0.001 to 1000 is used. The amount of the catalyst used in the first step of the present invention may vary depending on the activity of the catalyst used, but when the catalyst is continuously fed to the reaction system, the amount of the dialkyl carbonate and aromatic hydroxy in the feedstock is usually used. It is used in an amount of 0.0001 to 50% by weight, expressed as a ratio to the total weight of the compound. Further, when the solid catalyst is installed in the first continuous multi-stage distillation column and used, a catalyst amount of 0.01 to 75% by volume relative to the empty column volume of the first continuous multi-stage distillation column is used.

The liquid extracted from the lower part of the first continuous multi-stage distillation column can be directly supplied to the second step. At this time, when a catalyst that can be dissolved in the reaction solution under the reaction conditions is used, the catalyst used in the first step can be used as it is as the catalyst in the second step. In addition, after the liquid extracted from the lower part of the first continuous multi-stage distillation column is introduced into the first catalyst separation device and separated into a low boiling point component containing an alkylaryl carbonate and a high boiling point component containing an alkylaryl carbonate conversion catalyst, Second or part of the low boiling point component
Circulation by feeding to a continuous multi-stage distillation column, while
It is also a preferable method to circulate a part or all of the high boiling point component containing the catalyst by supplying it to the first continuous multi-stage distillation column. A distillation column or an evaporator is preferably used as the apparatus for separating the alkylaryl carbonate catalyst.

As the second continuous multi-stage distillation column used in the second step of the present invention, the same one as the above-mentioned first continuous multi-stage distillation column can be used. In the second step of the present invention, the catalyst can be present in the reaction system by continuously supplying the catalyst to the second continuous multi-stage distillation column, or
The catalyst can be present in the reaction system by arranging the solid catalyst in the continuous multi-stage distillation column.

When the catalyst is continuously supplied to the second continuous multi-stage distillation column, it may be supplied at the same time as the raw material or at a position different from the raw material. The catalyst may be supplied to any position other than the bottom of the tower. However, since the reaction actually takes place in the second continuous multi-stage distillation column from the catalyst feeding position to the lower region, it is preferable to feed the catalyst to the region from the tower top to the raw material feeding position. When a solid catalyst is used, the required amount of the catalyst can be packed in any position in the second continuous multistage distillation column. In the area where no catalyst exists in the first continuous multi-stage distillation column, it functions only as a normal distillation column such as concentration of reaction by-products.

In the present invention, the raw material can be supplied to any stage of the second continuous multistage distillation column from any number of inlets.
The raw material is a liquid or steam or a mixture of liquid and steam.
It is supplied to a continuous multi-stage distillation column. Further, in addition to supplying the raw material by liquid or vapor to the second continuous multi-stage distillation column, additionally supplying the raw material vapor to the lower part of the second continuous multi-stage distillation column,
Since it has the effect of substantially reducing the concentration of the dialkyl carbonate in the vapor phase rising in the second continuous multi-stage distillation column,
This is the preferred method.

In the second step of the present invention, the by-produced dialkyl carbonate is withdrawn in a gaseous state and recycled to the first continuous multi-stage distillation column. The gaseous extract may be a dialkyl carbonate alone, a raw material such as an alkyl aryl carbonate or a mixture with an aromatic hydroxy compound, may contain a small amount of an aliphatic alcohol, and May contain a small amount of diaryl carbonates.

The gas outlet for the dialkyl carbonate or the like in the second continuous multi-stage distillation column can be provided at any position other than the bottom of the column, but the concentration of the by-produced dialkyl carbonate in the distillation phase is usually , The higher the tower is. Therefore, it is preferable to provide a withdrawal outlet of the gas or the top portion between the overhead from the raw material supply position,
It is more preferable to provide it at the top of the tower.

In the second step of the present invention, the product diaryl carbonates are withdrawn in liquid form from the lower part of the second continuous multi-stage distillation column. The liquid extract may be a diaryl carbonate alone or a mixture with an alkylaryl carbonate as a raw material. It may contain a small amount of dialkyl carbonate or aromatic hydroxy compound. When a catalyst that can be dissolved in the reaction solution under reaction conditions is used, the liquid extract contains a catalyst component. Further, the liquid outlet for the diaryl carbonate or the like in the second continuous multi-stage distillation column is provided in the lower part of the column, particularly preferably in the bottom part of the column. Also, the second
The liquid extracted from the lower part of the column in the step is introduced into the second catalyst separation device, and is separated into a low boiling point component containing the diaryl carbonate and a high boiling point component containing the diaryl carbonate conversion catalyst, and then one of the high boiling point components containing the catalyst is separated. Part or all second
It is also a preferable method to circulate by feeding to a continuous multistage distillation column. A distillation column or an evaporator is used as the diarylcarbonation catalyst separation device.

In the present invention, the catalyst separation device can be used in either the first step or the second step, or can be used in both the first step and the second step. In the second step of the present invention, an aromatic hydroxy compound may be contained in the raw material supplied to the second continuous multi-stage distillation column, and the reaction product diaryl carbonate or the by-product dialkyl carbonate may be added. Although it may be contained, this reaction is a reversible reaction, and therefore, when the concentration of the dialkyl carbonate or diaryl carbonate is too high, the reaction rate of the raw material is lowered, which is not preferable. Therefore, usually, the amount of the dialkyl carbonate and the diaryl carbonate in the raw material is preferably 20 mol% or less, more preferably 10 mol% or less with respect to the alkyl aryl carbonate as the raw material.

The amount of the catalyst used in the second step of the present invention may vary depending on the activity of the catalyst used, but when the catalyst is continuously fed to the reaction system, it is usually the alkylaryl carbonate in the feedstock. Expressed as a ratio to the weight of 0.0001 to 50% by weight. Also,
When the solid catalyst is installed in the second continuous multi-stage distillation column and used, the amount of the catalyst used is 0.01 to 75% by volume based on the empty column volume of the reactive distillation column.

In carrying out the reactive distillation in the first step and the second step of the present invention, the reaction liquid descending rate and vapor ascending rate in the continuous multi-stage distillation column depend on the type of the continuous multi-stage distillation column used and a packed column is used. When it is carried out, it is usually carried out within a range where flooding does not occur, although it depends on the kind of the filling material. In the first step and the second step of the present invention, when the reflux ratio is increased, the distillation efficiency of the aliphatic alcohol or dialkyl carbonate, which is a reaction by-product, into the vapor phase becomes higher, so that the concentration of the reaction by-product in the vapor to be extracted is increased. Can be increased. However, if the reflux ratio is increased too much, the required heat energy becomes large, which is not preferable. Therefore, the reflux ratio is usually 0 to 10,
Preferably, 0-5 is used.

In the first step and the second step of the present invention, the reaction mainly takes place in the continuous multi-stage distillation column, so the amount of the reaction product produced depends on the amount of the hold-up liquid in the continuous multi-stage distillation column. That is, when a continuous multi-stage distillation column having the same column height and the same column diameter is used, a continuous multi-stage distillation column having a high liquid holdup is preferable in that the average residence time of the reaction liquid, that is, the reaction time becomes long.

However, when the liquid hold-up is too high, the retention time becomes long, so that side reactions easily proceed and flooding easily occurs. Therefore, the hold-up liquid amount of the distillation column used in the present invention may vary depending on the distillation conditions and the type of the distillation column, but is expressed by the volume ratio of the hold-up liquid amount to the empty column volume of the continuous multi-stage distillation column, and usually, It is performed at 0.005 to 0.75.

In carrying out the first step and the second step of the present invention, the reaction temperature is usually 50 to 350 ° C., preferably 100 to 280 ° C., although it varies depending on the kind of raw material used.
It is done in the range of. The reaction pressure varies depending on the type of raw material used and the reaction temperature, but is usually 0.00001 to
It is performed at 200 Kg / cm ² -G. In the first step and the second step of the present invention, the average residence time of the reaction liquid in the continuous multi-stage distillation column varies depending on the reaction conditions, the type of the continuous multi-stage distillation column, and the internal structure (for example, types of trays and packings). But,
Usually 0.001 to 50 hours, preferably 0.01 to 10 hours
Time, more preferably 0.05 to 2 hours.

In the first step and the second step of the present invention, it is not always necessary to use a solvent, but for the purpose of facilitating the reaction operation and the like, a suitable inert solvent such as ethers and aliphatic carbonization is used. Hydrogen, aromatic hydrocarbons, halogenated aliphatic hydrocarbons, halogenated aromatic hydrocarbons and the like can be used as a reaction solvent. In the first step and the second step of the present invention, an inert gas such as nitrogen, helium or argon may be allowed to coexist in the reaction system as a substance inert to the reaction. In addition, even if a low-boiling organic compound inert to the reaction is introduced in a gaseous state from the bottom of each continuous multi-stage distillation column for the purpose of accelerating the removal of by-produced aliphatic alcohols and dialkyl carbonates. Good.

[0085]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0086]

Example 1 (Preparation of catalyst) Diphenyl carbonate (20 kg) and lead monoxide (4 kg) were heated at 180 ° C. for 5 hours to generate carbon dioxide gas. After that, most of the remaining diphenyl carbonate was distilled off at a pressure of 10 mmHg, and the mixture was allowed to cool in a nitrogen atmosphere to prepare a catalyst (catalyst A).

(Production of Diphenyl Carbonate) An apparatus including two continuous multistage distillation columns shown in FIG. 1 was used. 1 m from the top (17) of the first continuous multistage distillation column (1), which is a packed column having a column height of 4 m and a column diameter of 3 inches, filled with stainless Dickson packing (diameter of about 6 mm) as a packing material. A mixture of dimethyl carbonate, phenol and catalyst A is continuously fed in liquid form from a raw material introduction pipe (2) through a conduit (4), a preheater (5) and a conduit (6), and a first continuous multi-stage distillation is carried out. The reaction was carried out by flowing down the inside of the tower.

The amount of heat required for the reaction and distillation was supplied by heating the lower liquid in the reboiler (10) through the conduits (8) and (9) and circulating it through the conduit (11). The gas continuously distilled from the top (17) of the column (1)
After 2), it was condensed in the condenser (13). A part of the condensate was refluxed to the first continuous multistage distillation column (1) via the conduits (14) and (15), and the rest was continuously withdrawn from the conduit (16). From this condensate, a low boiling point component containing methanol, which is a low boiling point reaction product, was obtained. The catalyst component and the high boiling point component containing methylphenyl carbonate were continuously withdrawn from the column bottom (18) via conduits (8) and (19).

Next, a tower with a height of 4 filled with stainless Dickson packing (diameter of about 6 mm) was used as a packing material.
m to the position 1 m from the top (26) of the second continuous multi-stage distillation column (20) consisting of a packed column having a column diameter of 3 inches, and the liquid extracted from the bottom of the first reactive distillation column through the conduit (19) in liquid form. The reaction is carried out by continuously feeding and flowing down in the second continuous multi-stage distillation column, and the heat quantity required for distillation is obtained by heating the lower liquid of the column through the conduits (28) and (29) in the reboiler (30). , By circulating through conduit (31).

In this second continuous multi-stage distillation column, the one used as the diaryl carbonate conversion catalyst in the first continuous multi-stage distillation column as the alkylaryl carbonate conversion catalyst was used as it was without separation. The gas containing dimethyl carbonate continuously distilled from the top (26) was condensed in the condenser (22) via the conduit (21). Part of the condensate was refluxed to the second continuous multistage distillation column (20) via conduits (23) and (24). The remaining condensate is continuously withdrawn from the conduits (23) and (25) and recirculated to the first continuous multistage distillation column (1) via the conduit (4), the preheater (5) and the conduit (6). Was done. Further, the high boiling point component containing the catalyst and diphenyl carbonate was continuously extracted from the bottom (27) of the second continuous multistage distillation column (20) via the conduits (28) and (32). Table 1 shows the reaction conditions and the results after steady state.

[0091]

Example 2 (Preparation of catalyst) 20 kg of phenol and 4 kg of dibutyltin oxide were heated at 180 ° C. for 10 hours, and water produced was distilled off together with phenol. After that, most of the phenol remaining at atmospheric pressure was distilled off, and the mixture was allowed to cool in a nitrogen atmosphere to prepare a catalyst (catalyst B). (Production of diphenyl carbonate) Using the same equipment as used in Example 1,
The same operation as in Example 1 was performed except that the catalyst B was used instead of the catalyst A. Table 1 shows the reaction conditions and the results after steady state.

[0092]

Example 3 (Preparation of catalyst) 20 kg of methylphenyl carbonate and 4 kg of primary lead acetate were heated at 180 ° C. for 10 hours. After that, most of the remaining methylphenyl carbonate and the like was distilled off at a pressure of 100 mmHg, and the mixture was allowed to cool in a nitrogen atmosphere to prepare a catalyst (catalyst C).

(Production of Diphenyl Carbonate) The apparatus shown in FIG. 2 was used. Filled with stainless Dickson packing (diameter about 6 mm) as a packing, tower height 4 m, tower diameter 3
From the top (17) of the first continuous multi-stage distillation column (1) composed of an inch packed column to a position 1 m from the top, a mixture of dimethyl carbonate, phenol and catalyst C is introduced from a raw material introduction pipe (2), a conduit (4), The liquid was continuously supplied through the preheater (5) and the conduit (6), and the reaction was carried out by flowing it down in the first continuous multi-stage distillation column (1).
The amount of heat required for the reaction and distillation depends on the dimethyl carbonate newly introduced from the introduction pipe (8 ') and a part of the low boiling point component including dimethyl carbonate recycled from the second continuous multistage distillation column (20) described later. And were heated in the evaporator (10 ') via conduit (9') and fed via conduit (11). The gas distilled from the tower top (17) passes through the conduit (12) and is condensed in the condenser (13).
It was continuously extracted from 6). From this condensate, a low boiling point reaction mixture containing a reaction product, methanol, was obtained. Further, the high boiling point reaction mixture containing methylphenyl carbonate and the catalyst component is fed from the bottom (18) to the conduit (19).
It was continuously extracted through.

Next, a Dickson packing made of stainless steel (diameter about 6 mm) was filled as a packing material, and the tower height was 4
m to the position 1 m from the top (26) of the second continuous multi-stage distillation column (20) consisting of a packed column having a column diameter of 3 inches, and a conduit (19) for the liquid extracted from the bottom of the first continuous multi-stage distillation column (1). The reaction is carried out by continuously supplying the liquid in the form of a liquid through the second continuous multi-stage distillation column (20), and the heat quantity required for the distillation is obtained by flowing the liquid at the bottom of the column through conduits (28) and (29) into a reboiler. Supplied by heating at (30) and circulating through conduit (31). In the second continuous multi-stage distillation column (20), the first diaryl carbonate conversion catalyst was used as the first catalyst.
The one used as the alkylaryl carbonate conversion catalyst in the continuous multistage distillation column (1) was used as it was without separation. The gas containing dimethyl carbonate continuously distilled from the top (26) was condensed in the condenser (22) via the conduit (21). Part of the condensate was refluxed to the second reactive distillation column (20) via conduits (23) and (24). The remaining condensate is continuously withdrawn from the conduits (23) and (25) and passes through the conduits (3) and (4), the preheater (5) and the conduit (6) to the first continuous multi-stage distillation column (1 ) Was circulated. A part of the condensate extracted from the conduit (25) was circulated from the lower part of the first continuous multistage distillation column (1) via the conduit (7) and the evaporator (10 ').
Further, the high boiling point reaction mixture containing the catalyst and diphenyl carbonate was continuously withdrawn from the bottom (27) of the second continuous multistage distillation column (20) via the conduits (28) and (32). Table 1 shows the reaction conditions and the results after steady state.

[0095]

Example 4 Using the same apparatus as used in Example 3, the same operation as in Example 3 was performed except that p-cresol was used instead of phenol. Table 2 shows the reaction conditions and the results after the steady state.

[0096]

Example 5 The same apparatus as that used in Example 3 was used, and the same operation as in Example 3 was carried out except that diethyl carbonate was used instead of dimethyl carbonate.
Table 2 shows the reaction conditions and the results after the steady state.

[0097]

Example 6 (Preparation of catalyst) 15 kg of phenol, 5 kg of methylphenyl carbonate and 4 kg of dibutyltin oxide were added to 1 part.
It heated at 80 degreeC for 10 hours, and distilled off the produced water together with phenol. After that, most of the phenol and methylphenyl carbonate remaining at normal pressure were distilled off, and the mixture was allowed to cool in a nitrogen atmosphere to prepare a catalyst (catalyst D).

(Production of Diphenyl Carbonate) The same apparatus as that used in Example 3 was used, and the same operation as in Example 3 was performed except that the catalyst D was used instead of the catalyst C. Table 2 shows the reaction conditions and the results after the steady state.

[0099]

Example 7 Using the same apparatus as used in Example 3, the same operation as in Example 3 was carried out except that tetraphenoxy titanium was used in place of catalyst C. Table 3 shows the reaction conditions and the results after the steady state.

[0100]

Example 8 (Preparation of catalyst) A catalyst was prepared by heating 20 kg of phenol and 4 kg of lead monoxide at 180 ° C. for 10 hours and distilling off the produced water together with phenol (catalyst E).
(Production of Diphenyl Carbonate) An apparatus as shown in FIG. 3 was used. Dimethyl carbonate, phenol and catalyst E to a position 0.5 m from the top (17) of the first continuous multi-stage distillation column (1) consisting of a tray column with a column height of 6 m and a column diameter of 10 inches equipped with 20 tray sieve trays. From the raw material introduction pipe (2) to the conduits (4) and (3
9), a preheater (5), and a conduit (6) to continuously feed in liquid form, and the reaction was carried out by flowing down in the first continuous multistage distillation column (1). The amount of heat required for the reaction and distillation is determined by the dimethyl carbonate newly introduced from the introduction pipe (8 ') and the conduit (9') and the conduits (24) and (25) from the second continuous multistage distillation column (20) described later. And part of the low-boiling reaction mixture containing dimethyl carbonate, which was circulated via (7), were heated in the evaporator (10 ') and fed via conduit (11). The gas distilled from the top (17) was condensed in the condenser (13) via the conduit (12) and continuously withdrawn from the conduit (16). From this condensate, a low boiling point reaction mixture containing a low boiling point reaction product, methanol, was obtained. Also at the bottom of the tower (1
The reaction liquid continuously withdrawn from 8) was introduced into the first evaporator (33) via the conduit (19). The residual liquid containing the methylphenylcarbonation catalyst is passed from the bottom of the evaporator (33) through the conduits (34), (38), (39), the preheater (5) and the conduit (6) to the first continuous multistage distillation column ( It was recycled to 1). The supply of the catalyst E introduced from the conduit (2) was stopped when the recirculated catalyst reached a predetermined concentration.

A part of the residual liquid flowing from the evaporator (33) through the conduit (34) is transferred to the conduit (35) and the reboiler (36).
And the methyl phenyl carbonate-containing evaporate evaporated from the evaporator (33) by circulating it to the evaporator (33) via the conduit (37) from the top (26) via the conduit (40). From a conduit (41) provided at a position of 5 m, it was continuously supplied to a second continuous multi-stage distillation column (20) consisting of a plate column equipped with a sieve tray having 20 plates and a column height of 6 m and a column diameter of 10 inches. . The diaryl carbonate conversion catalyst (catalyst E) is passed through the conduit (51) and then to the second conduit (48) provided at a position 1.5 m from the top of the tower.
Liquid was continuously fed to the continuous multistage distillation column (20).
Most of the gaseous methylphenyl carbonate supplied to the second continuous multi-stage distillation column (20) becomes liquid inside the column,
The reaction is carried out as it flows down in the tower with the catalyst.

The amount of heat required for the reaction and distillation was determined by the lower liquid of the column passing through conduits (28) and (29) to the reboiler (3
It was heated in 0) and fed by being sent to a distillation column (20) via a conduit (31). The low-boiling reaction mixture containing dimethyl carbonate, which was continuously distilled off from the top (26), was condensed in a condenser (22) via a conduit (21). Part of the condensate was refluxed to the second continuous multistage distillation column (20) via conduits (23) and (24). The remaining condensate is continuously withdrawn from the conduits (23) and (25) and passes through the conduits (3), (4) and (39), the preheater (5) and the conduit (6) to the first continuous multistage. It was recycled to the distillation column (1). A portion of the condensate continuously withdrawn from the conduit (25) is part of the conduits (7) and (9 ') and the evaporator (10').
And was recycled from the lower part of the first continuous multistage distillation column (1) via the conduit (11).

Further, the high boiling point reaction mixture containing the catalyst and diphenyl carbonate continuously withdrawn from the bottom (27) of the second continuous multi-stage distillation column (20) is introduced into the conduit (28).
And was introduced into the second evaporator (42) via (32). By evaporating a portion of the residual liquid flowing from the evaporator (42) through the conduit (43) through the conduit (44), the reboiler (45) and the conduit (46) to the evaporator can (42). ) Is evaporated from the conduit (5
2) and via a condenser (49) and a conduit (50), continuously in liquid form. The evaporate was mainly composed of diphenyl carbonate.

The residual liquid containing the diarylcarbonation catalyst was introduced from the bottom of the evaporator (42) into conduits (43), (4).
7) (48) and then recycled to the second continuous multistage distillation column (20). The supply of the catalyst E introduced from the conduit (51) was stopped when the circulating catalyst reached a predetermined concentration. Table 4 shows the flow rate and composition of each part. Table 5 shows the reaction conditions and the results after the steady state.

[0105]

Example 9 (Preparation of catalyst) After filling 5 kg of γ-alumina into a quartz glass cylinder (length 100 cm, diameter 10 cm), the cylinder was placed in a tubular furnace. After purging with nitrogen, it was heated at 200 ° C. for 5 hours to dry the γ-alumina. Next, γ-alumina was treated by adding a benzene solution of tetramethoxysilane (20 wt%) into the cylinder heated to 200 ° C. at a flow rate of 50 ml / hr for 10 hours. A catalyst was prepared by allowing to cool in a nitrogen atmosphere (catalyst F).

(Production of Diphenyl Carbonate) A packed column having a diameter of 1.5 inches and a height of 2 m was used as each of the first continuous multi-stage distillation column and the second continuous multi-stage distillation column, and the catalyst F was packed therein. The same operation as in Example 3 was performed except that the same one was used. Table 3 shows the reaction conditions and the results after the steady state.

[0107]

[Comparative Example 1] A distillation column (63) having a column height of 1 m and a column diameter of 1 inch shown in FIG. 4 [filled with stainless Dickson packing (diameter of about 6 mm)] and a stirrer (71), capacity A reaction kettle (62) of a 15-liter autoclave was charged with 12.8 kg of a liquid having the same composition as the liquid supplied from the conduit (6) of Example 2 through the conduit (61). The reaction was carried out while heating the reaction vessel (62) using an electric furnace (70) with stirring so that the liquid temperature became constant at 202 ° C. The gas distilled from the top (69) of the distillation column (63) was condensed in the condenser (65) via the conduit (64). A part of the condensate was refluxed through the conduit (67), and the rest was continuously taken out through the conduit (68) at a rate of 1.0 kg / hr. When 12.1 kg of the condensate was extracted, the reaction kettle (62) was cooled and the reaction liquid was introduced into the conduit (7
When extracted from 2), the weight was 0.7 kg. The ratio of the amount of the charged liquid and the amount of the liquid remaining in the kettle in this comparative example is the same as the ratio of the supply amount from the conduit (6) and the withdrawal amount of the bottom liquid from the conduit (28) in the second embodiment.

As a result of analysis, 14.0% by weight of diphenyl carbonate was formed in the reaction solution. The amount of diphenyl carbonate produced per 1 kg of reaction solution per hour is 1
It was 2 g / kg · hr. The selectivity of diphenyl carbonate based on phenol was 83%. Further, analysis of the condensate at the top of the column revealed that anisole was produced as a by-product with a selectivity based on phenol of 8%.

The results are shown in Example 2 (diphenyl carbonate production: 524 g / kg · hr, selectivity: 95
%), The method of the present invention is an excellent method capable of continuously producing diphenyl carbonate at a high reaction rate, a high selectivity and a high yield, and continuously.

[0110]

[Table 1]

[0111]

[Table 2]

[0112]

[Table 3]

[0113]

[Table 4]

[0114]

[Table 5]

[0115]

According to the method of the present invention, dialkyl carbonates and aromatic hydroxy compounds can be used as raw materials to continuously obtain diaryl carbonates with high yield and high selectivity.

[Brief description of drawings]

1 is a schematic diagram of an example process for practicing the present invention.

FIG. 2 is a schematic diagram of an example process for practicing the present invention.

FIG. 3 is a schematic diagram of an example process for practicing the present invention.

FIG. 4 is a schematic view of a reaction device used in Comparative Example 1.

[Explanation of Codes] 1 ... First continuous multi-stage distillation column 2, 8 '... Raw material introducing pipe 3, 4, 6, 7, 8, 9, 9', 11, 12, 14, 15, 16,
19, 21, 23, 24, 25, 28, 29, 31, 32, 34, 35, 37, 3
8, 39, 40, 41, 43, 44, 46, 47, 48, 50, 51, 52 ...
・ Conduit 5 ... Preheater 10, 30, 36, 45 ... Reboiler 10 '... Evaporator 13, 22, 49 ... Condenser 17, 26 ... Tower 18, 27 ... Column bottom 20 ・ ・ ・ Second continuous multi-stage distillation column 33,42 ・ ・ ・ Evaporator 61,64,66,67,68,72 ・ ・ ・ Conduit 62 ・ ・ ・ Reaction vessel 63 ・ ・ ・ Distillation column 65 ・ ・・ Condenser 69 ・ ・ ・ Tower 70 ・ ・ ・ Electric furnace 71 ・ ・ ・ Stirrer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B01J 31/12 C07B 61/00 300

Claims (7)

[Claims] 1. When producing a diaryl carbonate from a dialkyl carbonate and an aromatic hydroxy compound, (A) a raw material compound, a dialkyl carbonate and an aromatic hydroxy compound, are continuously fed into a first continuous multi-stage distillation column, In the first continuous multi-stage distillation column, the alkylaryl carbonate formation catalyst and the raw material compound are brought into contact with each other to cause a reaction, and the low boiling point component containing the by-produced aliphatic alcohol is continuously withdrawn in a gaseous state by distillation. A first step of continuously withdrawing a high boiling point component containing the generated alkylaryl carbonate in a liquid state from the lower part of the tower (B) a first step containing the alkylaryl carbonate
The liquid discharged from the lower part of the continuous multi-stage distillation column is continuously fed into the second continuous multi-stage distillation column, and the alkylaryl carbonate and the diaryl carbonate conversion catalyst are contacted in the second continuous multi-stage distillation column for reaction. While, the low boiling point component containing by-produced dialkyl carbonate is continuously withdrawn in a gaseous state by distillation, and a part or all of it is circulated by supplying it to the first continuous multi-stage distillation column in a gaseous or liquid state. A process for producing a diaryl carbonate, comprising a second step of continuously extracting a high boiling point component containing the produced diaryl carbonate in a liquid state from a lower part of the tower. 2. The method according to claim 1, wherein the alkylaryl carbonate formation catalyst is a catalyst that can be dissolved in the reaction solution under the reaction conditions and is continuously supplied to the first continuous multi-stage distillation column. 3. The method according to claim 1, wherein the diarylcarbonation catalyst is a catalyst that can be dissolved in the reaction solution under reaction conditions and is continuously supplied to the second continuous multistage distillation column. 4. The method according to claim 1, wherein the alkylaryl carbonate formation catalyst and / or the diaryl carbonate formation catalyst is a solid catalyst and is arranged inside a continuous multi-stage distillation column. 5. When supplying the lower-column withdrawal liquid of the first continuous multi-stage distillation column to the second continuous multi-stage distillation column, the extracted liquid is introduced into a first catalyst separation device, and a low boiling point component containing alkyl aryl carbonate and alkyl. After being separated into a high boiling point component containing an aryl carbonate conversion catalyst, a part or all of the low boiling point component is circulated by supplying it to the second continuous multi-stage distillation column, while a high boiling point component containing the catalyst is circulated. The method according to claim 2, wherein a part or the whole is supplied to the first continuous multi-stage distillation column for circulation. 6. The column bottoms of the second continuous multi-stage distillation column is introduced into a second catalyst separation device, and is separated into a low boiling point component containing a diaryl carbonate and a high boiling point component containing a diaryl carbonate conversion catalyst. The method according to claim 3, wherein a part or all of the high boiling point component containing the catalyst is supplied to the second continuous multistage distillation column for circulation. 7. When supplying the lower-column withdrawal liquid of the first continuous multi-stage distillation column to the second continuous multi-stage distillation column, the extracted liquid is introduced into a first catalyst separation device, and a low boiling point component containing alkyl aryl carbonate and an alkyl group. After being separated into a high boiling point component containing an aryl carbonate conversion catalyst, a part or all of the low boiling point component is circulated by supplying it to the second continuous multi-stage distillation column, while a high boiling point component containing the catalyst is circulated. A part or all of the solution is circulated by being supplied to the first continuous multi-stage distillation column for circulation, and the lower-column withdrawal liquid of the second continuous multi-stage distillation column is introduced to the second catalyst separation device, and the low boiling point component containing diaryl carbonate and diaryl carbonate are introduced. After separating into a high boiling point component containing a carbonation catalyst, a part or all of the high boiling point component containing the catalyst is fed to the second continuous multi-stage distillation column. The method according to claim 2 or 3, characterized in that the method is carried out by circulating it.