JPH0772158B2 - 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 efficiently producing a diaryl carbonate using a dialkyl carbonate and an aromatic hydroxy compound as raw materials.

[0002]

2. Description of the Related Art The following method has been conventionally proposed as a method for producing a diaryl carbonate. (1) A method for producing a diaryl carbonate by transesterifying a dialkyl carbonate and an aromatic hydroxy compound, for example,

[0003]

[Chemical 1] When a symmetrical dialkyl carbonate represented by (R is an alkyl group) and an aromatic monohydroxy compound represented by ArOH (Ar is a monovalent aromatic group) are reacted, the reaction formula is as follows. expressed.

[0004]

[Chemical 2] (2) A method for producing a diaryl carbonate and a dialkyl carbonate by disproportionating the alkyl aryl carbonate. For example,

[0005]

[Chemical 3] When the alkylaryl carbonate represented by (R and Ar are as described above) is reacted, the reaction is represented by the following formula.

[0006]

[Chemical 4] However, in these methods, the reactions are all equilibrium reactions, and the equilibrium is biased toward the original system, and the reaction rate is slow. It was very difficult to manufacture.

There are some suggestions to improve this.
However, most of them are for increasing the reaction rate.
It is related to catalyst development. Dialkyl carbonate
And an aromatic hydroxy compound
In the method for producing bonates, such a catalyst,
For example, Lewis acids or Lewis acids such as transition metal halides
Compounds that generate an acid [JP-A-51-105032]
JP-A-56-123948, JP-A-56-
No. 123949 (West German Patent Publication No. 252841)
No. 2, British Patent No. 1499530 No., US Patent No.
No. 4182726)], organotin alkoxides and
Tin compounds such as organic tin oxides [JP-A-54-4
8733 (West German Patent Publication No. 2736062)
No.), JP-A-54-63023, JP-A-60-1.
69444 (US Pat. No. 4,554,110)
, JP-A-60-169445 (US Pat. No. 4,
No. 552704), JP-A No. 62-277345.
Publication, Japanese Patent Application Laid-Open No. 1-265063], alkali metal
Or alkaline earth metal salts and alkoxides
(JP-A-56-25138), lead compounds (JP-A-56-25138)
57-176932), copper, iron, zirconium
Complexes of metals such as (Japanese Patent Application Laid-Open No. 183745/1982)
Report), titanates [JP-A-58-185536]
Publication (US Pat. No. 4,410,464)], Louis
A mixture of a souric acid and a protic acid [JP-A-60-173016]
Publication (US Pat. No. 4,609,501)], S
Compounds such as c, Mo, Mn, Bi, Te, etc.
-265064), ferric acetate (JP-A-61-1)
No. 72852) has been proposed. Also,
Diaryl carbonate disproportionate
The method of producing carbonate and dialkyl carbonate
Are such catalysts, for example Lewis acids and ruthenium.
Touch selected from transition metal compounds capable of generating isosic acid
Medium composition [JP-A-51-75044 (West German Patent
Japanese Laid-Open Publication No. 2552907, US Pat. No. 4,045,464
Specification)], a polymeric tin compound [JP-A-60-1
69444 (US Pat. No. 4,554,110)
)], The general formula R—X (═O) OH (wherein X is Sn and
Selected from Ti, R selected from monovalent hydrocarbon oxy groups
To be done. A compound represented by the formula [JP-A-60-16944]
5 (US Pat. No. 4,552,704)],
Mixture of isonic acid and protonic acid [Japanese Patent Application Laid-Open No. 60-17301]
6 (US Pat. No. 4,609,501)], lead
Catalyst (JP-A-1-93560), titanium and zirco
Aluminum compound (Japanese Patent Laid-Open No. 1-265062), tin
Compound (Japanese Patent Laid-Open No. 1-265063), Sc, M
Compounds such as o, Mn, Bi, Te (JP-A-1-265
No. 064) has been proposed.

Another attempt to improve the yield of diaryl carbonates in these reactions is to shift the equilibrium toward the production system as much as possible. As such a method, when a diaryl carbonate is produced from a dialkyl carbonate and an aromatic hydroxy compound, for example, in a reaction between dimethyl carbonate and phenol, methanol produced as a by-product is azeotropically distilled together with an azeotropic forming agent. Method of leaving [JP-A-54-4
8732 (West German Patent Publication No. 2736063)
), JP-A-61-291545], and a method of adsorbing and removing methanol by-produced by a molecular sieve [JP-A-58-185536 (US Pat. No. 4,104,64)]. Has been done.

In addition, as a preferable reaction system in the above-mentioned inventions proposed so far, alcohols by-produced by the reaction are separated from raw materials or products or coexisting solvents. In order to distill off, it is also known to use an apparatus in which a column having distillation or fractional distillation function is added to the upper part of the reactor [JP-A-56-1239].
48 (US Pat. No. 4,182,726), JP-A-56-25138, JP-A-60-169444 (US Pat. No. 4,554,110).
No. 60-169445 (US Pat. No. 4,552,704), JP-A No. 60-173016 (US Pat. No. 460950).
No. 1 specification), JP-A-61-272852, JP-A-61-291545, JP-A-62-277345].

[0010]

However, in any of these processes, it is clear that the reaction proceeds only in the reactor in which the catalyst is present. It is also clear that the distillation column section provided at the top of the reactor is only used to separate the alcohols produced in the reactor from the other components present in the reactor. This is described in detail in JP-A No. 61-291545, which describes, for example, "Reaction distillation at the bottom of a column is usually carried out by using reactive distillation in which a distillation column is added to the reactor. A reaction 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 a vessel "(the same page, right column, lines 12 to 17). Has been done.

That is, the reactive distillation in the above-mentioned methods is carried out by using a device in which a reaction part and a distillation part are separately present and only the distillation is carried out in the distillation column part and no reaction is carried out at all. It is a method characterized by that. Thus, in these methods, the reaction is carried out in the liquid phase in the reactor, but the low boiling point alcohol by-produced is extracted from the liquid phase to the gas phase through the gas-liquid interface, and then the reaction is equilibrated. Shifts to the production system side, and the reaction proceeds. 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, JP-A-61-29
In the examples of JP-A 1545 and JP-A-54-48732 and JP-A-54-48733, the reaction takes a batch-type reaction for a long time of 8 to 45 hours. In such a method that takes a long time, not only side reactions of raw materials and intermediates but also side reactions of the produced diaryl carbonates are likely to occur, resulting in a decrease in selectivity.

Further, in the conventional method called reactive distillation using an apparatus in which a reaction portion and a distillation portion exist separately, Japanese Patent Laid-Open Publication No. 61-291545 (page 3, left lower column, line 4). ~ Line 9), "the 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 preferred because it requires a large amount of equipment. ”In fact, in all the examples of the aforementioned patents proposed so far, the dialkyl carbonate and the aromatic group are used. At least one of the reaction reagents consisting of a hydroxy compound (usually an aromatic hydroxy compound which is a high-boiling compound) is reacted with the catalyst as it is initially charged in the reactor. A switch system. Therefore, a continuous reaction system in which a reaction reagent is continuously supplied and a product is continuously withdrawn has not been disclosed at all.

The present invention provides a method for continuously producing diaryl carbonates at a high reaction rate and a high selectivity without the drawbacks of the methods proposed so far. It was made for the purpose.

[0014]

DISCLOSURE OF THE INVENTION The present inventors have used a continuous multi-stage distillation column equipped with an external reactor in producing a diaryl carbonate from a dialkyl carbonate and an aromatic hydroxy compound in the presence of a catalyst. The present inventors have found that a reactive distillation column system for carrying out reaction and distillation is an excellent method that can easily achieve the above-mentioned object, and have completed the present invention based on this finding.

That is, according to the present invention, when a diaryl carbonate is produced from a dialkyl carbonate and an aromatic hydroxy compound, (A) the dialkyl carbonate and the aromatic hydroxy compound are continuously fed into the first continuous multi-stage distillation column, and the distillation column is The liquid flowing down the inside is withdrawn from a side withdrawal port provided in the middle stage and / or the lowest stage of the distillation column and introduced into a reactor provided outside the distillation column in the presence of an alkylaryl carbonate formation catalyst. After the reaction in step (1), it is circulated to the distillation column by introducing it into a circulation inlet provided in a stage above the stage having the extraction port, both in the reactor and in the distillation column or While reacting in the reactor, the low-boiling components including the produced aliphatic alcohol are continuously removed in a gaseous state by distillation from the distillation column. First step of discharging and continuously extracting a high boiling point component containing alkylaryl carbonate produced in a liquid state from the lower part of the tower (B) First containing alkylaryl carbonate
The liquid extracted from the lower part of the continuous multi-stage distillation column is continuously supplied into the second continuous multi-stage distillation column, and the liquid flowing down in the second continuous multi-stage distillation column is fed to the intermediate stage and / or the second continuous multi-stage distillation column. It is withdrawn from the side withdrawal port provided at the bottom, introduced into a reactor provided outside the second continuous multi-stage distillation column, and reacted in the presence of a diarylcarbonation catalyst, and then with a stage with the withdrawal port. By circulating it to the second continuous multi-stage distillation column by introducing it into the circulation inlet provided in the upper stage of the reactor, both in the reactor and in the second continuous multi-stage distillation column, or in the reactor. The low boiling point component containing the dialkyl carbonate to be produced is continuously extracted in a gaseous state by distillation, and part or all thereof is fed to the first continuous multi-stage distillation column in a gaseous state, a liquid state or a gas-liquid mixed state. thing Therefore circulate, it is the product high-boiling component containing the diaryl carbonate that is provided a process for producing diaryl carbonate, which comprises a second step of withdrawing continuously in a liquid form from a lower portion of the column.

The reason why the method of the present invention exhibits a high yield and a high selectivity as compared with the prior art is not clear, but the following is presumed.

That is, the main reactions in the first step and the second step of the present invention are represented by the formulas (I) and (III), respectively, and they are equilibrium reactions. And their equilibrium is extremely biased toward the origin.

Therefore, in any reaction step, in order to increase the reaction rate, a low boiling point product (usually an aliphatic alcohol in the first reaction step,
In the second reaction step, it is necessary to remove the dialkyl carbonate) from the reaction solution as quickly as possible.

However, in the reaction system described in the prior art, which uses a reaction vessel equipped with a distillation column, the reaction rate cannot be increased by any means. The reason for this is that not only the reaction field is limited to the part of the reaction vessel where the catalyst is present, but also the gas-liquid interface for evaporating the reaction by-product generated by the reaction from the liquid in the reaction vessel to the gas phase. This is because the area is small.

On the other hand, in the method of the present invention, a part or most of the liquid to be reacted, which continuously flows down in the first and second continuous multistage distillation columns, is fed to the middle stage and / or the intermediate stage of the distillation column. Alternatively, the distillation is carried out by extracting from the side extraction port provided at the lowest stage, introducing it into a reactor provided outside the distillation column for reaction, and then introducing it into a stage above the stage having the extraction port. Since it is a system in which it is circulated to the column, the reaction mixture with a high product concentration exiting the reactor is introduced into the distillation column with a large gas-liquid interface area, and the vapor rising from the bottom in the distillation column is By repeating gas-liquid contact, the low boiling point product in the reaction liquid can be efficiently evaporated into the vapor phase, and the concentration of the low boiling point reaction product in the liquid mixture flowing down in the distillation column can be reduced within a short time. Can be effectively reduced to Results can be obtained in a short time with a high yield of aromatic carbonates.

Further, in a reaction system using a reaction kettle having a distillation column installed in the upper part, the reaction rate cannot be increased, so that the residence time in the reaction kettle is long, and therefore a side reaction proceeds to increase the selectivity. However, according to the method of the present invention, it is possible to obtain the product with a short residence time, and it is considered that the selectivity is increased.

The dialkyl carbonate used as the raw material compound in the present invention has the general formula

[0023]

[Chemical 5] (R ¹ and R ² represent an alkyl group, an alicyclic group or an aralkyl group, R ¹ and R ² may be the same or different, and R ¹ and R ² may be a ring. It may be a constituent component). Examples of R ¹ and R ² include methyl, ethyl, propyl (each isomer), allyl, butyl (each isomer), butenyl (each isomer), pentyl (each isomer), hexyl (each isomer). Body), heptyl (each isomer), octyl (each isomer), nonyl (each isomer), decyl (each isomer), cyclohexylmethyl, and other alkyl groups; cyclopropyl,
Alicyclic groups such as cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl; aralkyl such as benzyl, phenethyl (each isomer), phenylpropyl (each isomer), phenylbutyl (each isomer), methylbenzyl (each isomer) The group is raised.

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), diallyl 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), 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 the raw material compound used in the present invention is represented by the general formula Ar ¹ OH (2) (Ar ¹ represents an aromatic group), and is directly attached to the aromatic group. Any one may be used as long as it has a hydroxy group bonded. A like this
Examples of r ¹ include phenyl, tolyl (each isomer),
Xylyl (each isomer), trimethylphenyl (each isomer), tetramethylphenyl (each isomer), ethylphenyl (each isomer), propylphenyl (each isomer), butylphenyl (each isomer), diethylphenyl (Each isomer), methylethylphenyl (each isomer), pentylphenyl (each isomer), hexylphenyl (each isomer),
Phenyl groups and various alkylphenyl groups such as cyclohexylphenyl (each isomer); various alkoxyphenyl groups such as methoxyphenyl (each isomer), ethoxyphenyl (each isomer), butoxyphenyl (each isomer); Various halogenated phenyl groups such as fluorophenyl (each isomer), chlorophenyl (each isomer), bromophenyl (each isomer), chloro (methylphenyl) (each isomer), dichlorophenyl (each isomer); formula

[0028]

[Chemical 6] [However, A is a bond, or -O-, -S-,-
CO -, - SO ₂ - ₂ divalent group such as or,

[0029]

[Chemical 7] Alkylene groups or substituted alkylene groups such as (where 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, which may be optionally substituted with a halogen atom or an alkoxy group), or

[0030]

[Chemical 8] Represents a cycloalkylene group (wherein k is an integer of 3 to 11, and a 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. It may be substituted with a substituent such as a lower alkoxy group, an ester group, a hydroxyl group, a nitro group, a halogen or a cyano group. ] Various phenyl groups represented by: naphthyl (each isomer), methylnaphthyl (each isomer), dimethylnaphthyl (each isomer), chloronaphthyl (each isomer), methoxynaphthyl (each isomer), cyano Naphthyl groups such as naphthyl (each isomer) and various substituted naphthyl groups; pyridyl (each isomer), coumaryl (each isomer), quinolyl (each isomer),
Examples include various substituted and unsubstituted heteroaromatic groups such as methylpyridyl (each isomer), chlorpyridyl (each isomer), methylcoumaryl (each isomer), and methylquinolyl (each isomer).

Examples of the 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) , Various alkylphenols such as dipropylphenol (each isomer), methylbutylphenol (each isomer), pentylphenol (each isomer), hexylphenol (each isomer), cyclohexylphenol (each isomer); methoxyphenol ( Each isomer), ethoxyphenol (each isomer) Wherein;) various alkoxy phenols such as

[0032]

[Chemical 9] (A is as described above) various substituted phenols; naphthol (each isomer) and various substituted naphthols; hydroxypyridine (each isomer), hydroxycoumarin (each isomer), hydroxyquinoline (each isomer) Heteroaromatic hydroxy compounds such as are used. In addition, aromatic dihydroxy compounds having two hydroxyl groups such as hydroquinone, resorcin, catechol, dihydroxynaphthalene, dihydroxyanthracene and their alkyl-substituted dihydroxy compounds;

[0033]

[Chemical 10] (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.). Etc. can also be used. Of these aromatic hydroxy compounds, Ar ¹ preferably has 6 carbon atoms.
An aromatic monohydroxy compound consisting of 10 to 10 aromatic groups, and particularly preferred is phenol.

The term "alkylaryl carbonate" as used in the present invention refers to a dialkyl carbonate represented by the above formula (1) in which one alkyl group is substituted with an aromatic group.

[0035]

[Chemical 11] (R ³ is R ¹ or R ² , and R ¹ , R ² and Ar ¹ are as described above). When the aromatic hydroxy compound (Ar ¹ OH) represented by the formula (2) is an aromatic dihydroxy compound Ar ² (OH) ₂ (4) having two hydroxyl groups, the general formula

[0036]

[Chemical 12] (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) are also included in the alkylaryl carbonate.

Examples of such alkylaryl carbonates include methylphenyl carbonate, ethylphenyl carbonate, propylphenyl carbonate (each isomer), allylphenyl carbonate, butylphenyl carbonate (each isomer), pentylphenyl carbonate (each isomer). ), Hexyl phenyl carbonate (each isomer), heptyl phenyl carbonate (each isomer), octyl tril carbonate (each isomer), nonyl (ethyl phenyl) carbonate (each isomer), decyl (butyl phenyl) carbonate (each isomer) Body), methyl tolyl carbonate (each isomer), ethyl tolyl carbonate (each isomer), propyl tolyl carbonate (each isomer), butyl tolyl carbonate (each isomer), allyl tolyl carbonate Bonate (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), 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-
Examples thereof include (hydroxyphenyl) propylphenyl carbonate (each isomer), ethyl 2- (hydroxyphenyl) propylphenyl carbonate (each isomer), and the like.

The diaryl carbonate referred to in the present invention is a dialkyl carbonate in which two alkyl groups are substituted by an aromatic group and has a general formula

[0039]

[Chemical 13] (Ar ¹ and Ar ² are as described above, Ar ³ represents the same aromatic group as described in Ar ¹ , and Ar ⁴ represents the same divalent aromatic group as described in 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), di [2- (hydroxyphenylpropyl) phenyl] carbonate (various isomers), and the like.

In the first step of the present invention , the aliphatic alcohol produced is withdrawn in a gaseous state and the produced alkyl is produced.
The aryl carbonates are extracted in liquid form from the lower part of the tower.
Therefore, in the first step of the present invention , the dialkyl carbonate and the aromatic hydroxy compound are used in a combination such that the boiling point of the resulting aliphatic alcohol is lower than the boiling point of the product alkylaryl carbonate. To be done. Such a preferable combination is represented by the formula (1)
In the aromatic hydroxy compound represented by the formula (2) or (4) and the dialkyl carbonate represented by
R ¹ and R ² are alkyl groups having 1 to 4 carbon atoms, and Ar ¹
Alternatively, Ar ² may be 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 alkylaryl carbonate formation catalyst, and any catalyst can be used as long as it can produce an alkylaryl carbonate by the reaction of a dialkyl carbonate and an aromatic hydroxy compound. But it can be used. For example, (lead compounds) PbO, PbO ₂ , Pb ₃ O ₄ and other lead oxides; PbS, Pb ₂ S and other lead sulfides; Pb (OH) ₂ ,
Lead hydroxides such as Pb ₂ O ₂ (OH) ₂ ; Na ₂ PbO, K
Zinc salts such as ₂ PbO ₂ , NaHPbO ₂ and KHPbO ₂ ; Na ₂ PbO ₃ , Na ₂ H ₂ PbO ₄ , K ₂ PbO ₃ and K ₂
[Pb (OH) ₆ ], K ₄ PbO ₄ , Ca ₂ PbO ₄ , Ca
Lead acid salts such as _{PbO 3; PbCO 3, 2PbCO 3} · P
lead carbonate such as b (OH) ₂ and its basic salts;
Pb (OCOCH ₃ ) ₂ , Pb (OCOCH ₃ ) ₄ , Pb
Lead salts of organic acids such as (OCOCH ₃ ) ₂ · PbO · 3H ₂ O and their carbonates and basic salts; Bu ₄ Pb, Ph ₄ P
b, Bu ₃ PbCl, Ph ₃ PbBr, Ph ₃ Pb (or Ph ₆ Pb ₂ ), Bu ₃ PbOH, Ph ₃ PbO and other organic lead compounds (Bu represents a butyl group, Ph represents a phenyl group); Pb ( OCH ₃ ) ₂ , (CH ₃ O) Pb (OP
h), alkoxy leads such as Pb (OPh) ₂ and aryloxy leads; Pb-Na, Pb-Ca, Pb-Ba,
Alloys of lead, such as Pb-Sn, Pb-Sb; Hoenn ore, lead minerals such as Sen'aen ore, and hydrates of these lead compounds; (copper _{compound) CuCl, CuCl 2, CuBr,} CuB
r ₂ , CuI, CuI ₂ , Cu (OAc) ₂ , Cu (ac
ac) ₂ , copper oleate, Bu ₂ Cu, (CH ₃ O) ₂ C
u, AgNO _3, AgBr, picric silver, AgC ₆ H ₆
ClO ₄ , Ag (bulvarene) ₃ NO ₃ , [AuC≡C-
C (CH ₃ ) ₃ ] _n [Cu (C ₇ H ₈ ) Cl] _{4 and} other copper group metal salts and complexes (acac represents an acetylacetone chelate ligand); (alkali metal complex) Li (acac) , LiN (C
₄ H ₉ ) ₂ etc. alkali metal complex; (zinc complex) Zn (acac) ₂ etc. zinc complex; (cadmium complex) Cd (acac) ₂ etc. cadmium complex; (iron group metal compound ) Fe (C ₁₀ H ₈ ) (CO) ₅ , Fe
(CO) ₅ , Fe (C ₄ H ₆ ) (CO) ₃ , Co (mesitylene) ₂ (PEt ₂ Ph) ₂ , CoC ₅ F ₆ (CO) ₇ , Ni−
Iron group metal complexes such as π-C ₅ H ₅ NO and ferrocene; (Zirconium complex) Zr (acac) ₄ , zirconocene and other zirconium complexes; (Lewis acid compounds) AlX ₃ , TiX ₃ , TiX ₄ , V
OX ₃ , VX ₅ , ZnX ₂ , FeX ₃ , SnX ₄ (where X is
Is a halogen, an acetoxy group, an alkoxy group, an aryloxy group) or the like, and a Lewis acid and a transition metal compound generating a Lewis acid; (organotin compound) (CH ₃ ) ₃ SnOCOCH ₃ , (C ₂
H ₅ ) ₃ SnOCOC ₆ H ₅ , Bu ₃ SnOCOCH ₃ , Ph
₃ SnOCOCH ₃ , Bu ₂ Sn (OCOCH ₃ ) ₂ , Bu ₂
Sn (OCOC ₁₁ H ₂₃ ) ₂ , Ph ₃ SnOCH 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 (O
CH ₃ ) ₂ , (C ₂ H ₅ ) ₃ SnOH, Ph ₃ SnOH, Bu
₂ SnO, (C ₈ H ₁₇ ) ₂ SnO, Bu ₂ SnCl ₂ , Bu
Organotin compounds such as SnO (OH); (Solid catalysts) Solid catalysts such as silica, alumina, titania, silica-titania, zinc oxide, zirconium oxide, gallium oxide, zeolites, oxides of rare earths; Surface acids of these solid catalysts Those obtained by modifying points 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 are particularly preferably used;
Lead hydroxides such as Pb (OH) ₂ and Pb ₂ O ₂ (OH) ₂ ;
PbCO ₃ , 2PbCO ₃ .Pb (OH) ₂ and other lead carbonates and their basic salts; Pb (OCH ₃ ) ₂ , (CH
₃ O) Lead compounds such as alkoxyleads such as Pb (OPh) and Pb (OPh) ₂ and aryloxyleads, and further, those lead compounds reacted with an organic compound present in the reaction system, Alternatively, those obtained by heating these lead compounds with a raw material or a product prior to the reaction 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 a diaryl carbonate from an alkyl aryl carbonate.
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 multistage distillation column used in the first step and the second step of the present invention is a distillation column having a multistage number of distillation stages of 2 or more, and if continuous distillation is possible. It can be anything. (The number of distillation columns in the present invention indicates the number of trays in the case of a plate column, and the theoretical number for a packed column type and other distillation columns.) Such a continuous multi-stage distillation column Examples of the tray tower type using trays such as bubble bell tray, perforated plate tray, valve tray, countercurrent tray, Raschig ring, Lessing ring, Pall ring, Berlu 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 distillation column having both a tray part and a part filled with 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.

First and second used in the method of the present invention
Any number of side withdrawal ports provided on the side of the continuous multi-stage distillation column can be provided between the middle stage and / or the bottom stage of the distillation column. Also, the circulation inlet may be above the corresponding side outlet,
Any number can be provided. When the first and / or second continuous multistage distillation column is provided with a plurality of side outlets, the liquids withdrawn from two or more different side outlets can be combined and introduced into the reactor. When a plurality of vessels are used, two or more different reaction solutions can be joined together and then introduced into the circulation inlet.
Moreover, these can also be combined. Preferably, when the number of reactors provided outside the first and second continuous multi-stage distillation columns is two or more, and the stages of liquid withdrawal ports from the distillation columns connected to the reactors are different from each other. More preferably, the number of reactors provided outside the first and second continuous multi-stage distillation columns is two or more, and the stages of liquid withdrawal ports from the distillation columns connected to the reactors are respectively. This is the case where the stages of the circulation inlets that are different and that are provided in the distillation column for circulating from the reactor to the distillation column are different stages.

In the present invention, a reactor is provided between the side outlets of the first and second continuous multi-stage distillation columns and the circulation inlet to the distillation column. The reactor is a flow type. It may be of any type as long as it is a tubular reactor, a stirring tank type flow reactor, or the like.

In the process of the present invention, it is necessary that at least a catalyst is present in these reactors, and in addition, the catalyst is also present inside the first and / or second continuous multistage distillation column. Is also preferable.

Any method may be used for allowing the catalyst to be present in the reactor or in the reaction system consisting of the reactor and the first and / or second continuous multi-stage distillation column. In the case of a homogeneous catalyst that dissolves in a reaction solution under reaction conditions, the catalyst can be present in the reaction system by continuously supplying the catalyst to the reactor and / or the distillation column, Alternatively, in the case of a heterogeneous catalyst which does not dissolve in the reaction solution under the reaction conditions, the catalyst is present in the reaction system by disposing the solid catalyst in the reactor or both in the reactor and in the distillation column. You can let it
A method in which these are used in combination, for example, a method in which a solid catalyst is placed in the reactor and / or the distillation column and then a homogeneous catalyst is used may be used.

In the first step of the present invention, the raw material compound consisting of the dialkyl carbonate and the aromatic hydroxy compound is continuously fed into the first continuous multi-stage distillation column. In this case, it is directly introduced into the distillation column. Alternatively, these raw material compounds may be introduced into the reactor and introduced as a reaction solution into the distillation column. In addition, these raw material compounds are separately or / and mixed from any number of inlets,
It can be introduced into any stage or / and any reactor of the distillation column.

The raw material compound is supplied in the form of a liquid or a gas or a gas-liquid mixture of a liquid and a gas.

Thus, in addition to continuously supplying the raw material compound into the first continuous multi-stage distillation column and / or the reactor, an additional gaseous raw material compound is intermittently or continuously supplied from the lower part of the distillation column. Is also a preferable method.

Of the dialkyl carbonate and the aromatic hydroxy compound, the raw material having a higher boiling point is in a liquid or gas-liquid mixed state in the uppermost reactor and / or in the upper stage than the liquid withdrawal stage to the uppermost reactor. , Continuous supply,
A method of continuously supplying a lower boiling material in a gaseous state from the lower part of the distillation column is also a preferable method, and a lower boiling material is continuously fed to the lowermost reactor in a liquid state, a gaseous state, or a gas-liquid mixed state. It is also preferable to supply the same. In this case, it does not matter if the low boiling point raw material is contained in the high boiling point raw material supplied from the upper portion.

These feed materials may contain the product aliphatic alcohol and alkylaryl carbonate or diaryl carbonate, but since this reaction is a reversible reaction, the concentration of these products is not so high. When it is high, the reaction rate of the raw material is lowered, which is not preferable.

In the first step of the present invention, the aliphatic alcohol produced is withdrawn in gaseous form. 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 outlet for gas consisting of 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 aliphatic alcohol produced 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 are 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 usually refers to a portion between the raw material supply position and the bottom of the column, and usually refers to a portion near the bottom of the column.

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
It is also a preferred method to circulate by supplying to the continuous multi-stage distillation column, while circulating a part or all of the high boiling point component containing the catalyst 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.

In the second step of the present invention, the lower-column withdrawal liquid of the first continuous multi-stage distillation column is continuously fed into the second continuous multi-stage distillation column. In this case, it is introduced directly into the distillation column. Alternatively, the liquid extracted from the lower part of the first continuous multi-stage distillation column may be introduced into the reactor, and the reaction liquid may be introduced into the distillation column. In addition, the liquid extracted from the lower part of the first continuous multi-stage distillation column may be introduced into any stage and / or any reactor of the distillation column from any number of inlets.

The liquid extracted from the lower part of the first continuous multi-stage distillation column is supplied as a liquid or a gas or a gas-liquid mixture of liquid and gas.

As described above, the bottom liquid extracted from the first continuous multi-stage distillation column is continuously supplied to the second continuous multi-stage distillation column and / or the reactor provided outside the second continuous multi-stage distillation column. It is also a preferable method to additionally and intermittently or continuously feed a gaseous aromatic hydroxy compound and / or alkylaryl carbonate from the lower part of the second distillation column.

The distillate at the bottom of the first continuous multi-stage distillation column may contain the dialkyl carbonate which is the product of the second step, but since this reaction is a reversible reaction, the concentration of these products Is too high, the reaction rate of the alkylaryl carbonate decreases, which is not preferable.

In the second step of the present invention, the produced dialkyl carbonate is withdrawn in a gaseous state and recycled to the first continuous multistage 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 outlet for the gas composed of 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 produced dialkyl carbonate in the vapor phase is
Usually the higher the tower 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 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 first step and the second step of the present invention, the falling liquid rate and the vapor rising rate in the first and second continuous multi-stage distillation columns depend on the type of the reactive distillation column used and when a packed column is used. Is different depending on the kind of the filling material, but is usually carried out in a range where flooding does not occur.

In the first step and the second step of the present invention, the liquid flowing down from the side withdrawal port provided in the middle stage and / or the lowest stage into the distillation column with the side withdrawal port is provided. Part or most of it is withdrawn and introduced into the reactor. The residence time in the reactor is usually 0.001 to 100 hours, preferably 0.003 to 50 hours.
The time is more preferably 0.01 to 10 hours.

In the first step and the second step of the present invention, in addition to the reaction in the reactor, the reaction can also be carried out in the continuous multi-stage distillation column if necessary, which is a preferable method. In this case, the amount of reaction product produced also depends on the amount of holdup liquid in the distillation column. That is, when the distillation column having the same column height and the same column diameter is used, a distillation column having a high liquid holdup is preferable in that the average residence time of the reaction liquid inside the distillation column, 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 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 it is usually expressed as a volume ratio of the hold-up liquid amount to the empty volume of the reactive distillation column and is usually 0. 0.005-0.75
Done in.

In the first step and the second step of the present invention,
Although the residence time of the reaction solution in the distillation column may vary depending on the reaction conditions, it is usually 0.001 to 50 hours, preferably 0.
It takes from 01 to 10 hours.

In the first step and the second step of the present invention, when the reflux ratio is increased, the distillation efficiency of the low boiling point reaction product, aliphatic alcohol or dialkyl carbonate, into the vapor phase is increased, so that The concentration of low boiling reaction products 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 2
0 is used, and preferably 0 to 10 is used.

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. Further, when the reaction is carried out both in the reactor and in the distillation column, the reaction can be carried out at different reaction temperatures and pressures.

The reaction pressure may be any of reduced pressure, normal pressure and increased pressure, although it depends on the type of raw material used and the reaction temperature, and is usually 1 mmHg to 200 kg / cm ² -G.

As described above, in the method of the present invention, since the reactor is provided outside the continuous multistage distillation column, it is possible to adopt reaction conditions of temperature and pressure different from the distillation conditions (temperature and pressure). When the above reactors are provided, different reaction conditions can be adopted.

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 carbon 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. Also,
For the purpose of accelerating the removal of by-produced aliphatic alcohols and dialkyl carbonates, an inert gas or a low-boiling organic compound inert to the reaction may be introduced in a gaseous state from the lower part of each continuous multi-stage distillation 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.

In the second step of the present invention, the raw material supplied to the second continuous multi-stage distillation column may contain an aromatic hydroxy compound, or may be a reaction product such as diaryl carbonate or a by-product. Dialkyl carbonate may be contained, but since this reaction is a reversible reaction,
If the concentration of the dialkyl 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 dialkyl carbonate and diaryl carbonate in the raw material is usually 20 mol% with respect to the raw material alkylaryl carbonate.
The following is preferable, and 10 mol% or less is more preferable.

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 100.

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, it is usually mixed with the dialkyl carbonate in the feedstock. It is used in an amount of 0.0001 to 50% by weight, expressed as a ratio to the total weight of the aromatic hydroxy compound. When a solid catalyst is used, it is usually 10 to 100% by volume, preferably 50 to 100% by volume with respect to the inner volume of the reactor. When the solid catalyst is installed inside the distillation column, the amount of the catalyst used is 0.01 to 75% by volume based on the empty column volume of the first continuous multistage distillation column.

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, the alkylaryl carbonate in the feed is usually used. Expressed as a ratio to the weight of 0.0001 to 50% by weight. Also,
When a solid catalyst is used, it is 1 for the internal volume of the reactor.
0 to 100% by volume, preferably 50 to 100% by volume. Further, when the solid catalyst is installed inside the distillation column, it is 0.01 to the empty volume of the second continuous multistage distillation column.
A catalytic amount of 75% by volume is used.

[0081]

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

Example 1 (Preparation of catalyst) 20 kg of diphenyl carbonate and 4 kg of lead monoxide were heated at 180 ° C. for 5 hours to generate carbon dioxide gas. Thereafter, 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) The first step and the second step were performed using the apparatus shown in FIG. The number of reactors in the first step is four. Each of the reactors A, B, C, and D had an internal volume of 0.5 l, and each was filled with stainless Dickson packing (6φ) as a packing material. Column height 4 packed with the same packing as that of the reactor
m, a dimethyl carbonate at a position 1 m from the top 17 of the first continuous multi-stage distillation column 1 composed of a packed column having a column diameter of 3 inches,
A mixture of phenol and catalyst A was continuously supplied in liquid form from the raw material introduction pipe 2 through the conduit 4, the preheater 5, and the conduit 6. The liquid flowing down in the distillation column 1 was extracted from a side extraction port 53 provided in the middle stage of the distillation column 1, and then introduced into each of the reactors A to D. The reaction liquid in which the reaction proceeded in the reactors A to D and the concentration of the alkylaryl carbonate and the concentration of the aliphatic alcohol were increased was circulated from the circulation inlet 54 to the distillation column 1. The concentration of the aliphatic alcohol decreased as the liquid flowing down in the distillation column 1 came into gas-liquid contact with the vapor rising from the column bottom 18 of the distillation column 1 toward the column top 17. The amount of heat required for distillation was supplied by heating the lower liquid of the column with the reboiler 10. The gas distilled from the top 17 of the column was condensed in the condenser 13 via the conduit 12. A part of the condensate was refluxed to the first continuous multistage distillation column 1 via the conduit 15, and the rest was extracted from the conduit 16.
From this condensate, a low boiling point component containing methanol, which is a by-product of the reaction, was obtained. Further, the high boiling point component including the catalyst component and methylphenyl carbonate was withdrawn from the column bottom 18 via conduits 8 and 19. In this way, the first step was performed.

The number of reactors in the second step is four. Each of the reactors E, F, G, and H had an internal volume of 0.5 l, and each was filled with stainless Dickson packing (6φ) as a packing material. The second continuous multistage distillation column 20 composed of a packed column having a column height of 4 m and a column diameter of 3 inches packed with the same packing as that of the reactor was moved to a position 1 m from the top 26 of the first continuous multistage distillation column. The liquid taken out from the bottom of the column was continuously fed in a liquid form through a conduit 19. The liquid flowing down inside the distillation column 20 was extracted from a side extraction port 53 provided at an intermediate stage of the distillation column 20, and then introduced into each of the reactors E to H. The reaction liquid in which the reaction proceeded in the reactors E to H and the diaryl carbonate concentration and the dialkyl carbonate concentration were increased was circulated from the circulation inlet 54 to the distillation column 20. The concentration of the dialkyl carbonate decreased as the liquid flowing down in the distillation column 20 came into gas-liquid contact with the vapor rising from the column bottom 27 of the distillation column 20 toward the column top 26. The amount of heat required for distillation was supplied by heating the lower liquid of the column with a reboiler 30. In this second continuous multi-stage distillation column 20, the first diaryl carbonate conversion catalyst
The one used as the catalyst for alkylaryl carbonate formation in the continuous multi-stage distillation column 1 was used as it was without being separated. The gas containing dimethyl carbonate distilled from the column top 26 was condensed in the condenser 22 via the conduit 21. A part of the condensate was refluxed to the second continuous multistage distillation column 20 via the conduit 24. The remaining condensate is drained from conduit 25,
It was circulated to the first continuous multistage distillation column 1 via the preheater 5 and the conduit 6. Further, a high boiling point component containing the catalyst and diphenyl carbonate was obtained from the bottom 27 of the second continuous multi-stage distillation column 20 via conduits 28 and 32. In this way, the second step was performed. The reaction conditions and the results after steady state are shown in Tables 1 to 4.

Example 2 (Preparation of catalyst) 20 kg of phenol and 4 kg of dibutyltin oxide were heated at 180 ° C. for 10 hours, and the produced water 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) The first step and the second step were carried out in the same manner as in Example 1 except that the same apparatus as that used in Example 1 was used and the catalyst B was used instead of the catalyst A.
The process was carried out. The reaction conditions and the results after steady state are the first
It shows in Table-Table 4.

Example 3 (Preparation of catalyst) 20 kg of methylphenyl carbonate and 4 kg of lead (I) 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 first step and the second step were performed using the apparatus shown in FIG. The number of reactors in the first step is four. Each of the reactors A, B, C, and D had an internal volume of 0.5 l, and each was filled with stainless Dickson packing (6φ) as a packing material. Column height 4 packed with the same packing as that of the reactor
dimethyl carbonate to a position 1 m from the top 17 of the first continuous multi-stage distillation column 1 consisting of a packed column having a diameter of 3 m and a column diameter of 3 inches,
A mixture of phenol and catalyst C is continuously supplied in a liquid form from a raw material introduction pipe 2 through a conduit 4, a preheater 5 and a conduit 6, and the reaction is carried out by flowing down in the first continuous multi-stage distillation column 1. It was The amount of heat required for the reactive distillation is to heat the dimethyl carbonate newly introduced from the conduit 8'in the evaporator 10 'and a part of the low boiling point component including dimethyl carbonate circulated from the second continuous multi-stage distillation column 20. Supplied by The gas distilled from the column top 17 was condensed in the condenser 13 via the conduit 12 and extracted from the conduit 16. From this condensate, a low boiling point component containing methanol, which is a by-product of the reaction, was obtained. Further, the high boiling point component including methylphenyl carbonate and the catalyst component was withdrawn from the column bottom 18 via a conduit 19. In this way, the first step was performed.

The number of reactors in the second step is four. Each of the reactors E, F, G, and H had an internal volume of 0.5 l, and each was filled with stainless Dickson packing (6φ) as a packing material. The first continuous multi-stage distillation column 1 is located at a position 1 m from the top 26 of the second continuous multi-stage distillation column 20 which is a packed column having a column height of 4 m and a column diameter of 3 inches, which is packed with the same packing as that of the reactor. The column bottom withdrawal liquid of was continuously fed in liquid form via conduit 19. The liquid flowing down inside the distillation column 20 is a side extraction port 5 provided at an intermediate stage of the distillation column.
After being withdrawn from 3, it was introduced into each reactor EH.
The reaction liquid in which the reaction proceeded in the reactors E to H and the diaryl carbonate concentration and the dialkyl carbonate concentration were increased was circulated from the circulation inlet 54 to the distillation column 20. The liquid flowing down in the distillation column 20 is the bottom 2 of the distillation column 20.
The concentration of the dialkyl carbonate decreased as the vapor-liquid contact was made with the vapor rising from No. 6 toward the tower top 27. The amount of heat required for distillation was supplied by heating the lower liquid of the column with a reboiler 30. 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 multi-stage distillation column 1 was used as it was without separation. The gas containing dimethyl carbonate distilled from the column top 26 was condensed in the condenser 22 via the conduit 21. A part of the condensate was refluxed to the second continuous multistage distillation column 20 via the conduit 24. The remaining condensate was extracted from the conduit 25, circulated to the first continuous multistage distillation column 1 via the preheater 5 and the conduit 6. 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, a high boiling point component containing the catalyst and diphenyl carbonate was obtained from the bottom 27 of the second continuous multi-stage distillation column 20 via conduits 28 and 32. In this way, the second step was performed. The reaction conditions and the results after steady state are shown in Tables 1 to 4.

Example 4 (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 D). (Production of diphenyl carbonate) The first step and the second step were carried out using the apparatus shown in FIG. First
The number of reactors in the process is four. Reactor A, B, C, D
Each had an internal volume of 4 l, and each was filled with stainless Dickson packing (6φ) as a filling material. Dimethyl carbonate from the top 17 to 0.5 m from the top 17 of the first continuous multi-stage distillation column 1 consisting of a plate column with a column height of 6 m and a column diameter of 10 inches equipped with 20 sieve trays.
A mixture of phenol and catalyst E was continuously supplied in liquid form from the raw material introduction pipe 2 through the conduit 4, the preheater 5, and the conduit 6. The liquid flowing down in the distillation column 1 was extracted from a side extraction port 53 provided in the middle stage of the distillation column 1, and then introduced into each of the reactors A to D. The reaction liquid in which the reaction proceeded in the reactors A to D and the concentration of the alkylaryl carbonate and the concentration of the aliphatic alcohol were increased was circulated from the circulation inlet 54 to the distillation column 1. The concentration of the aliphatic alcohol decreased as the liquid flowing down in the distillation column 1 came into gas-liquid contact with the vapor rising from the column bottom 18 of the distillation column 1 toward the column top 17. The amount of heat required for distillation is evaporator 1
It was supplied by heating the dimethyl carbonate newly introduced from the conduit 8 ′ at 0 ′ and a part of the low boiling point component containing dimethyl carbonate circulated from the second continuous multistage distillation column 20. The gas distilled from the tower top 17 is the conduit 1
After passing through 2, it was condensed in the condenser 13 and extracted from the conduit 16. From this condensate, a low boiling point component containing methanol, which is a by-product of the reaction, was obtained. Further, the reaction liquid extracted from the column bottom 18 was introduced into the evaporator 33 which is the first catalyst separation device via the conduit 19. The high-boiling component including the methylphenylcarbonation catalyst is supplied from the bottom of the evaporator 33 to the conduit 34,
It was circulated to the first continuous multistage distillation column 1 via 38 and 39 and the preheater 5. The supply of the catalyst E introduced from the conduit 2 was stopped when the circulating catalyst reached a predetermined concentration. In this way, the first step was performed. The gas consisting of a low boiling point component containing methylphenyl carbonate, which was distilled from the evaporator 33 by being heated by the reboiler 36, passed through a conduit 40 and an inlet pipe 41 provided at a position 1.5 m from the tower top 26, It was continuously supplied to the second continuous multi-stage distillation column 20 comprising a tray column having a column height of 6 m and a column diameter of 10 inches equipped with a sieve tray having 20 plates. The diaryl carbonate conversion catalyst (catalyst E) was continuously supplied in liquid form to the second continuous multi-stage distillation column from an inlet pipe 48 provided at a position 1.5 m from the top of the column via a conduit 51. Most of the gaseous methylphenyl carbonate supplied to the second continuous multi-stage distillation column becomes liquid inside the column, and this flows down through the catalyst and inside the column to carry out the reaction.

The number of reactors in the second step is four. Each of the reactors E, F, G, and H had an internal volume of 0.5 l, and each was filled with stainless Dickson packing (6φ) as a packing material. The liquid flowing down inside the distillation column 20 was extracted from a side extraction port 53 provided at an intermediate stage of the distillation column 20, and then introduced into each of the reactors E to H. The reaction liquid in which the reaction proceeded in the reactors E to H and the diaryl carbonate concentration and the dialkyl carbonate concentration were increased was circulated from the circulation inlet 54 to the distillation column 20. The concentration of the dialkyl carbonate decreased as the liquid flowing down in the distillation column 20 came into gas-liquid contact with the vapor rising from the column bottom 27 of the distillation column 20 toward the column top 26. The amount of heat required for distillation was supplied by heating the lower liquid of the column with a reboiler 30. The low boiling point component containing dimethyl carbonate distilled from the column top 26 was condensed in a condenser 22 via a conduit 21. A part of the condensate was refluxed to the second continuous multistage distillation column 20 via the conduit 24. The remaining condensate was extracted from the conduit 25, circulated to the first continuous multistage distillation column 1 via the preheater 5 and the conduit 6. 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 '. The high boiling point component containing the catalyst and diphenyl carbonate extracted from the bottom 27 of the second continuous multi-stage distillation column 20 is passed through the conduits 28 and 32 and the evaporator 42 which is the second catalyst separation device.
Was introduced to. The components distilled from the evaporator 42 by being heated by the reboiler 45 are supplied to the conduit 52 and the condenser 49.
It was extracted as a liquid through. This distillate was mainly composed of diphenyl carbonate. The high boiling point component containing the diaryl carbonate conversion catalyst was circulated from the bottom of the evaporator 42 to the second continuous multistage distillation column via conduits 43, 47 and 48. The supply of the catalyst E introduced from the conduit 51 was stopped when the circulating catalyst reached a predetermined concentration. In this way, the second step was performed. The reaction conditions and the results after steady state are shown in Tables 1 to 4.

Comparative Example 1 A distillation column 63 having a tower height of 1 m and a tower diameter of 1 inch shown in FIG.
A liquid 12 having the same composition as the liquid supplied from the conduit 6 of Example 2 was placed in a reaction vessel 62 of an autoclave having a capacity of 15 liters, which was equipped with [Dixon packing (6φ) made of stainless steel] and an agitator 71. 0.8 kg was charged from the conduit 61. The reaction was carried out while heating the reaction kettle 62 using the electric furnace 70 while stirring and keeping the liquid temperature 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. Part of the condensate was refluxed through the conduit 67, and the rest was continuously withdrawn from the conduit 68 at a rate of 1.0 kg / hr. When 12.1 kg of the condensate was withdrawn, the reaction kettle 62 was cooled and the reaction liquid was withdrawn from the conduit 72, and the weight was 0.7 kg. The ratio of the amount of charged liquid to the amount of liquid remaining in the kettle in this comparative example is the same as the ratio of the amount of supply from the conduit 6 and the amount of bottom liquid withdrawn from the conduit 32 in Example 2. As a result of analysis, 14.0% by weight of diphenyl carbonate was formed in the reaction solution. Reaction solution 1 per hour
The amount of diphenyl carbonate produced per kg is 12 g /
It was kg · hr. The selectivity of diphenyl carbonate based on phenol was 83%. Further, when the condensate was analyzed, anisole as a reaction by-product was detected. The anisole selectivity based on phenol was 5%. Comparing this result with the result of Example 2 (diphenyl carbonate production amount: 561 g / kg · hr, selectivity 95%), it is shown that the method of the present invention can provide the diaryl carbonate in high yield and high selectivity. ing.

[0090]

[Table 1]

[0091]

[Table 2]

[0092]

[Table 3]

[0093]

[Table 4]

[0094]

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]

FIG. 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 diagram of a reaction apparatus used in Comparative Example 1.

[Explanation of symbols]

1 1st continuous multistage distillation column 5 Preheater 10,30,36,45 Reboiler 10 'Evaporator 13,22,49 Condenser 17,26 Tower top 18,27 Tower bottom A, B, C, D, E, F , G, H Reactors 53A, 53B, 53C, 53D, 53E, 53F, 5
3G, 53H Side extraction port 54A, 54B, 54C, 54D, 54E, 54F, 5
4G, 54H Circulation inlet 20 Second continuous multi-stage distillation column 33 Evaporator can that is the first catalyst separator 42 Evaporator can that is the second catalyst separator 62 Reactor 63 Distillation tower 65 Condenser 70 Electric furnace 71 Stirrer

Claims (8)

[Claims] 1. When producing a diaryl carbonate from a dialkyl carbonate and an aromatic hydroxy compound, (A) the dialkyl carbonate and the aromatic hydroxy compound are continuously fed into the first continuous multi-stage distillation column, and the distillate is flowed down. Liquid is extracted from a side extraction port provided in the middle stage and / or the lowest stage of the distillation column, introduced into a reactor provided outside the distillation column, and reacted in the presence of an alkylaryl carbonate formation catalyst. After that, it is circulated to the distillation column by introducing it into a circulation inlet provided at a stage above the stage having the outlet, and both inside the reactor and inside the distillation column or the reactor. While the reaction is carried out in the reactor, the low boiling point component containing the produced aliphatic alcohol is continuously withdrawn in a gaseous state by distillation from the distillation column to produce the product. The containing Killua reel carbonates first step of continuously withdrawn in a liquid form from a lower portion of the column a high-boiling component containing a (B) alkylaryl carbonates 1
The liquid extracted from the lower part of the continuous multi-stage distillation column is continuously supplied into the second continuous multi-stage distillation column, and the liquid flowing down in the second continuous multi-stage distillation column is supplied to the intermediate stage and / or the second continuous multi-stage distillation column. It is withdrawn from the side withdrawal port provided at the lowest stage, introduced into a reactor provided outside the second continuous multistage distillation column, and reacted in the presence of a diarylcarbonation catalyst, and then with a stage with the withdrawal port. Both the inside of the reactor and the inside of the second continuous multi-stage distillation column by introducing the same into the second continuous multi-stage distillation column by introducing them into the circulation inlet provided in the upper stage. The low boiling point component containing the resulting dialkyl carbonate is continuously extracted in a gaseous state by distillation, and part or all thereof is fed to the first continuous multistage distillation column in a gaseous state, a liquid state or a gas-liquid mixed state. Especially Circulated I, continuous process for preparing diaryl carbonates which comprises a second step of withdrawing a high boiling point component containing the diaryl carbonate to produce continuously in a liquid form from a lower portion of the column. 2. The number of reactors provided outside each of the first and second continuous multi-stage distillation columns is two or more, and the stage of the liquid withdrawing port from the distillation column connected to the reactors comprises:
The method according to claim 1, wherein the steps are different from each other. 3. Two or more reactors are provided outside the first and second continuous multistage distillation columns, respectively, and are provided in the distillation column for circulation from the reactor to the distillation column. The method according to claim 2, wherein the stages of the circulation inlets are different stages. 4. An alkylaryl carbonate-forming catalyst and / or diaryl carbonate-forming catalyst is obtained by continuously supplying to the distillation column and / or the reactor a catalyst that can be dissolved in the liquid in the distillation column and the reactor. The method according to claim 1, wherein the method is present. 5. An alkylaryl carbonate formation catalyst by arranging a solid catalyst which is substantially insoluble in the liquid in the distillation column and in the reactor both in the reactor and in the distillation column or in the reactor. And / or the presence of a diarylcarbonation catalyst is present in any one of claims 1, 2 or 3. 6. When the lower-column withdrawal liquid of the first continuous multi-stage distillation column is fed to the second continuous multi-stage distillation column, the withdrawal liquid is introduced into a first catalyst separation device, and a low-boiling component containing alkylaryl 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 4, wherein a part or the whole is supplied to the first continuous multistage distillation column for circulation. 7. The liquid extracted from the lower part 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 4, 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. 8. When supplying the liquid extracted from the lower part 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. 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. 5. The method according to claim 4, characterized in that it is circulated.