JP3412475B2 - Polycarbonate manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to the production of a diaryl oxalate such as diphenyl oxalate (DPO) from a dialkyl oxalate and a phenol compound in the first step, and removal of the diaryl oxalate from CO in the second step.
Diaryl carbonate such as diphenyl carbonate (DPC) and by-product carbon monoxide are produced by reaction, and the diaryl carbonate and polyvalent hydroxy compound are subjected to polycondensation reaction in the third step to give polycarbonate and by-product. And a phenolic compound that is a product,
The present invention relates to a method for producing a polycarbonate by an industrially completely novel production process in which the phenol compound is separated and recovered, circulated / supplied to the first step, and reused as a raw material for the reaction in the first step. .

Polycarbonate is an extremely important polymer which is useful as an electric / electronic material product such as a compact disc and an industrial material product such as an organic glass and a lens because it is excellent in mechanical strength, transparency and electric characteristics. is there.

[0003]

2. Description of the Related Art Conventionally, a method for producing a polycarbonate has been obtained by polycondensing a diaryl carbonate such as diphenyl carbonate (DPC) obtained by various known methods and a polyvalent hydroxy compound such as a bisphenol compound. Was there. Examples of the method for producing a diaryl carbonate such as diphenyl carbonate (DPC), which is a raw material of polycarbonate, include a method of producing an ester exchange reaction from a dialkyl carbonate obtained by a known method, and a method of directly producing phosgene and a phenol compound (phosgene method). ) And other various manufacturing methods have been proposed, but these manufacturing methods are not always industrially satisfactory.

That is, in the typical method for producing a diaryl carbonate by the phosgene method described in Japanese Patent Publication No. 58-50977, since a highly toxic phosgene is used, its toxicity is extremely problematic. In addition, impurities of halogen compounds are mixed in the obtained diaryl carbonate in a considerable content ratio, and it may not be easy to remove impurities of the halogen compounds. When used in the production of polycarbonate, problems may occur in the polymerization degree, transparency, etc. of the polycarbonate.

As a method for producing a diaryl carbonate without using phosgene (non-phosgene method), a method for obtaining a diaryl carbonate by transesterifying a dialkyl carbonate and a phenol compound (Japanese Patent Laid-Open No. 2912/1993)
57 and JP-A-4-21138), or a method for producing a dialkyl carbonate and a diaryl carbonate by a disproportionation reaction of an alkylaryl carbonate (see JP-A-4-9358). Was there.

However, in the method for producing dialkyl carbonate by transesterification, the transesterification reaction is a two-step equilibrium reaction via an alkylaryl carbonate as an intermediate, and the reaction rate of the reaction for producing diaryl carbonate is slow. is there. In order to improve these points, various special catalysts and various complicated manufacturing processes and manufacturing apparatuses have been proposed. (JP-A-4-235
(See Japanese Patent Laid-Open No. 951 and Japanese Patent Laid-Open No. 4-224547)

Further, in the above-mentioned production method by disproportionation of an alkylaryl carbonate, the alkylaryl carbonate is an intermediate product in the above-mentioned transesterification reaction, and a mixed solution of the transesterification reaction containing other products and raw materials ( It is extremely difficult to isolate only the alkyl aryl carbonate from the reaction solution), and it is also difficult to industrially produce and obtain the alkyl aryl carbonate itself, so that it is not a satisfactory industrial process. There wasn't.

That is, as a method for producing a diaryl carbonate, a method of transesterifying a dialkyl carbonate such as dimethyl carbonate with a phenol compound such as phenol has been expected to be industrialized as a typical example of the non-phosgene method. However, in reality, it was a fairly complicated manufacturing method industrially.

On the other hand, as a method for producing diaryl oxalate, oxalic acid and a phenol compound are heated in an organic solvent at 100 to 130 ° C. in the presence of an esterification catalyst to directly undergo an esterification reaction to produce a diaryl oxalate. Method (see Japanese Examined Patent Publication No. 52-43826), a method for producing an aryl oxalate by reacting a dialkyl oxalate and a diaryl carbonate (Japanese Examined Patent Publication No. 56-56).
-8019 and JP-A-49-42621), or a method for producing a diaryl oxalate by transesterifying a dialkyl oxalate and a lower fatty acid aryl ester (Japanese Patent Publication No. 56-2541 and Japanese Patent Publication No. 2541). No. 57-47658) is known.

However, the known method for producing a diaryl oxalate by directly esterifying an oxalic acid and a phenol compound has a problem that the reaction takes a long time because the reaction rate is extremely slow, and from an industrial point of view. It was not a satisfactory method. In addition, a method for producing an aryl oxalate by reacting a dialkyl oxalate with a diaryl carbonate or a lower fatty acid aryl ester is used in order to separate the aryl oxalate because various by-products other than the target product are produced in a considerably large amount. There is a problem that an extremely complicated purification step is required, and, as mentioned above, the diaryl carbonate itself is not easily industrially produced and is difficult to obtain, so that it is not necessarily industrially satisfactory. It wasn't the right recipe.

Further, for the de-CO reaction of diaryl oxalate, refer to "Organic Synthetic Chemistry, 5, Report 47 (194).
8) ”“ Pyrolysis of dicarboxylic acid diphenyl ester (second report) ”, there is a report that diphenyl carbonate was pyrolyzed at high temperature to obtain diphenyl carbonate. However, this report only describes that a mixture of oxalic anhydride, carboxylic acid, and phosphorus oxychloride was heated as a method for producing diphenyl oxalate, and the dialkyl oxalate and the phenol compound in the present invention were described. There is no description about a method for producing diaryl oxalate by the reaction of.

And, US Pat. No. 4,544,50
No. 7 discloses a method for producing a carbonate by heating oxalate in a solvent in the presence of an alcoholate catalyst to a temperature of 50 to 150 ° C., wherein diphenyl oxalate is used as the oxalate. An embodiment is shown in which, when used, the main product was diphenyl oxalate (there is no statement that diphenyl carbonate was formed).

Further, the above-mentioned US patent specification does not specifically describe a method for producing a diaryl oxalate from a dialkyl oxalate, and the reaction of the dialkyl oxalate with a phenol compound in the present invention results in a diaryl oxalate. There is no suggestion of how to make the rate.

[0014]

DISCLOSURE OF THE INVENTION The inventors of the present invention can solve the problems in the method for producing a polycarbonate using diphenyl carbonate obtained by the conventionally known phosgene method or non-phosgene method, and moreover, "dialkyl oxalate". As a result of diligent research on a method of producing a polycarbonate through a diphenyl carbonate using a rate as a raw material, it is possible to industrially easily synthesize a diaryl oxalate such as diphenyl oxalate by reacting a dialkyl oxalate with a phenol compound.
A diaryl carbonate such as diphenyl carbonate can be industrially obtained by subjecting the diaryl oxalate to a CO deoxidation reaction, and the polycarbonate and a by-product phenol compound can be produced by subjecting the diaryl carbonate and a polyvalent hydroxy compound to a polycondensation reaction. Was obtained, and it was found that the phenol compound can be reused in the first reaction, and the production method of the polycarbonate of the present invention, which is a novel production process, was completed. The present invention industrially synthesizes a diaryl carbonate such as diphenyl carbonate by a non-phosgene method, obtains a polycarbonate using the diaryl carbonate, and a phenol compound as a by-product in the reaction between the first dialkyl oxalate and the phenol compound. It is the first to offer a new manufacturing process for reuse.

[0015]

According to the present invention, in the first step, a dialkyl oxalate is reacted with a phenol compound to produce a diaryl oxalate, and in the second step, the diaryl oxalate is subjected to a CO reaction to remove the diaryl carbonate and the secondary compound. Carbon monoxide is produced in the organism, and further, in the third step, the diaryl carbonate and the polyvalent hydroxy compound are subjected to polycondensation reaction to separate and recover the by-product phenol compound to produce a polycarbonate, which is recovered. It relates to a method for producing a polycarbonate, characterized in that a phenol compound is circulated / supplied to the first step and reused in the reaction of the first step.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 1, the production method of the present invention is as follows. The first step of the synthesis of diaryl oxalate by the reaction of dialkyl oxalate and a phenol compound, the diaryl by the de-CO reaction of diaryl oxalate. It is carried out according to a continuous process in which the second step of carbonate synthesis and the third step of polycarbonate synthesis by polycondensation reaction of diaryl carbonate and polyhydric hydroxy compound are linked.

As the production method of the present invention, for example, in the first step, a dialkyl oxalate (particularly dimethyl oxalate) and a phenol compound (particularly phenol) are reacted in the liquid phase in the presence of a transesterification catalyst to give a diaryl Oxalate (particularly diphenyl oxalate) and a by-product lower alcohol (particularly methanol) are produced, and the diaryl oxalate is separated / purified and recovered, and lower alcohol (particularly methanol) is separated and recovered, and The diaryl oxalate is decarbonated in two steps.
In the presence of O catalyst, CO is removed in the liquid phase to generate diaryl carbonate (particularly DPC) and by-product carbon monoxide, and diaryl carbonate is separated from the reaction mixture while discharging carbon monoxide out of the reaction system.・ Refining and collecting
Then, in the third step, the polyaryl hydroxy compound and the polyvalent hydroxy compound are subjected to a polycondensation reaction while separating the phenol compound in the presence of an appropriate polymerization catalyst to produce a polycarbonate, and the recovered phenol compound is recycled to the first step. -The method of supplying and reusing in the reaction of the first step can be preferably mentioned.

The dialkyl oxalate used in the first step in the production method of the present invention is, for example, dimethyl oxalate, diethyl oxalate, dipropyl oxalate,
Examples thereof include dialkyl oxalates (having a lower alkyl group having 1 to 6 carbon atoms) such as dibutyl oxalate, dipentyl oxalate and dihexyl oxalate. The dialkyl oxalate has the following formula (1)
Carbon monoxide (CO) and alkyl nitrite (RONO; especially methyl nitrite) are reacted in the gas phase in the presence of a platinum group metal-based catalyst according to the reaction formula shown in FIG. NO) with dialkyl oxalate (a)
(Especially dimethyl oxalate). It is industrially preferable that the by-produced nitric oxide is reacted with a lower alcohol in the presence of molecular oxygen to regenerate the RONO and reused in the synthesis reaction of the dialkyl oxalate, if necessary.

[0019]

[Chemical 1]

In RONO in the formula (1), R is methyl group, ethyl group, n-propyl group, isopropyl group, n-
It is a lower alkyl group having 1 to 6 carbon atoms such as a butyl group and an isobutyl group, and examples thereof include methyl nitrite, ethyl nitrite, n-propyl nitrite, isopropyl nitrite, n-butyl nitrite, and nitrite. Preferable examples are alkyl nitrites having 1 to 4 carbon atoms such as isobutyl.

The synthesis reaction of dialkyl oxalate is carried out, for example, by liquid phase reaction of carbon monoxide and nitrite in the presence of a platinum group metal-based catalyst, as described in Japanese Patent Publication No. 56-12624. Then, under pressure of 2 to 500 atm, and in gas phase reaction under pressure of 2 to 20 atm, 10 to 20 atm.
It can be performed in a liquid phase or a gas phase at a temperature of 0 ° C., particularly about 20 to 150 ° C. The reaction may be a batch system or a continuous system, but the continuous system is industrially preferable because the reaction heat can be easily removed. The nitrite is used in a concentration of 2% by weight or more, particularly 5 to 60% by weight, and further 10 to 50% by weight in the liquid phase reaction, and 1 to 30% by volume in the gas phase reaction. It is particularly preferable to use it at a concentration of 5 to 20% by volume. The carbon monoxide used in this reaction may be pure or may be diluted with an inert gas such as nitrogen. The partial pressure of carbon monoxide in the diluting gas is preferably 5 to 200 atm in the liquid phase reaction. The “carbon monoxide gas by-produced in the second step of the present invention” described below is used as the dialkyl It can be used for oxalate synthesis reaction.

Examples of the platinum group metal-based catalyst used in the synthesis reaction of the above dialkyl oxalate include, for example, platinum group metals such as platinum metal and palladium metal or salts thereof (palladium mineral acid such as palladium nitrate and palladium phosphate). Salts, palladium halides such as palladium chloride, palladium acetate such as palladium acetate, palladium oxalate, and palladium benzoate), or their complexes (palladium alkylphosphine complexes, palladium arylphosphine complexes, and other palladium complexes) ) Can be preferably mentioned. The platinum group metal-based catalyst is used by supporting it on an inert carrier such as activated carbon, alumina (γ-alumina, α-alumina, etc.), spinel, silica, diatomaceous earth, pumice, zeolite, molecular sieve, etc. Is preferred. In the liquid phase reaction, the platinum group metal-based catalyst described above is used in an amount of 0.1 wt ppm to 2 wt%, particularly 1 to 500 wt p based on the reaction mixture in terms of platinum group metal.
It may be used in the range of about pm. In the gas phase reaction, a catalyst in which 0.01 to 5% by weight of platinum group metal, a salt thereof, or a complex thereof is supported on the carrier in terms of platinum group metal may be used.

The synthesis reaction of dialkyl oxalate may be carried out without a solvent or in a solvent inert to this reaction (for example, aliphatic or aromatic dicarboxylic acid diester, dialkyl carbonate, ethers, aromatic or aliphatic hydrocarbon compound). , Their halides, etc.).

In the reaction in the first step of the present invention, the dialkyl oxalate (a) and the phenol compound (b) obtained as described above are esterified according to, for example, the following reaction formulas (2) and (3). By the exchange reaction, alkylaryl oxalate (c-1), diaryl oxalate (c-2) and lower alcohol (d) are mainly produced. Then, the alkylaryl oxalate (c-1) is disproportionated as shown in the reaction formula (4) to mainly produce the diaryl oxalate (c-2) and the dialkyl oxalate (a). It is preferable that those reactions are carried out in a liquid phase, and all of them are equilibrium reactions.

[0025]

[Chemical 2]

In the reaction in the first step of the present invention, all of the reactions of the above reaction formulas (2) to (4) have occurred, but the alkylaryl oxalate (mainly by the transesterification reaction of the reaction formula (2). c-1) and the lower alcohol (d) are produced, and then the diaryl oxalate (c-2) and the dialkyl oxalate are mainly produced by the disproportionation reaction (one of transesterification reactions) of the reaction formula (4). The reaction of producing (a) is performed. That is, the first aspect of the present invention
The reaction in the step is mainly performed by the transesterification reaction of the reaction formula (2) and the disproportionation reaction of the reaction formula (4). Then, in the end, in the reaction in the first step, the diaryl oxalate (c-2) and the lower alcohol (d) are produced from the dialkyl oxalate (a) and the phenol compound (b).

In the reaction formulas (2), (3) and (4), R represents an alkyl group having 1 to 6 carbon atoms as described above, Ar represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group, A phenyl group which may have various substituents such as halogen. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group and a butyl group, and examples of the alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, Propoxy group, butoxy group and the like can be preferably mentioned, and as halogen, chlorine, bromine, iodine and fluorine can be mentioned.

In the first step of the present invention, for example, a dialkyl oxalate and a phenol compound are reacted in the liquid phase in the presence of a transesterification catalyst while removing the lower alcohol produced outside the reaction system to give a diaryl oxalate. Is generated, separated and recovered. More specifically, in the first step of the present invention, for example, a dialkyl oxalate and a phenol compound are subjected to a transesterification reaction in a liquid phase while removing a lower alcohol produced in the presence of a transesterification catalyst from the reaction system, An alkylaryl oxalate is produced, and the alkylaryl oxalate is then subjected to a disproportionation reaction in a liquid phase in the presence of the catalyst while removing the produced dialkyl oxalate to produce a diaryl oxalate, which is then separated. It is to be collected.

As a specific example of the above-mentioned first step, for example, as shown in FIGS. 2 and 3, a method using a first reactive distillation column and a second reactive distillation column can be mentioned. That is, the dialkyl oxalate, the phenolic compound and the transesterification catalyst are supplied from the line 4 to the first reactive distillation column 1 to evaporate the lower alcohol produced and withdraw it from the top to remove it to the outside of the reaction system. A reaction mainly consisting of a transesterification reaction between a phenol compound and a phenol compound (the transesterification reaction of the reaction formula (2)) is carried out in the presence of a transesterification catalyst, and then the reaction liquid (can liquid 3) is subjected to the first reactive distillation. It is withdrawn from the bottom of the column 1 and supplied to the second reactive distillation column 10 to distill the by-product dialkyl oxalate, the unreacted dialkyl oxalate in the transesterification reaction and the phenolic compound, and withdraw them from the top to remove them. However, the reaction mainly composed of the disproportionation reaction of the alkylaryl oxalate of the reaction formula (4) is performed by the same catalyst. How to carry out in the presence can be exemplified.

The reaction liquid obtained in the first step of the present invention is, for example, a raw material and a catalyst, and an alkylaryl oxalate (particularly methylphenyl oxalate) which is a reaction intermediate.
And a target diaryl oxalate (particularly diphenyl oxalate) and a by-product lower alcohol (particularly methanol; a by-product in the above transesterification reaction)
And dialkyl oxalate (especially dimethyl oxalate; a by-product in the above-mentioned disproportionation reaction) are mainly contained, and other by-products are extremely small in amount. The diaryl oxalate can be easily separated, purified and recovered from the reaction solution.

As a specific example of this separation / purification and recovery, for example, a method using a distillation apparatus and an evaporation apparatus as shown in FIGS. 2 and 3 can be mentioned. That is, the reaction liquid (can liquid 13) extracted from the bottom of the second reactive distillation column 10 is supplied to the distillation device 20 for distillation operation, or is supplied to the evaporation device 30 and the distillation device 20. A method of separating and purifying the diaryl oxalate by performing evaporation and distillation operations and recovering it can be mentioned. In addition, a crystallization method for precipitating a crystalline adduct of diaryl oxalate and a phenol compound (for example, a crystalline adduct of 1 mol of diphenyl oxalate and 2 mol of phenol) from the above reaction liquid (container 3). Another method is to recover the diaryl oxalate by separating and purifying the crystalline adduct and recovering the crystalline adduct, and then evaporating and removing the phenol compound from the crystalline adduct.

Separation and purification of the reaction liquid (can liquid 13) withdrawn from the second reactive distillation column 10 is carried out, for example, as shown in FIG. The catalyst component is separated by evaporating, and the evaporate is separated into the first distillation column 40.
And the light fraction vapor (alkylaryl oxalate and phenol compound) is extracted from the top of the first distillation column 40 and condensed, and a bottom liquid containing diaryl oxalate as a main component is extracted from the bottom of the first distillation column 40. It can be carried out by extracting and supplying it to the second distillation column 20, cooling the vapor of the diaryl oxalate from the top of the second distillation column 20, extracting it via the line 21, and collecting it. Also,
Although not shown, the reaction solution is first subjected to a distillation operation in the first distillation column to withdraw and remove the light component vapor from the top of the first distillation column, and the diaryl oxalate as a main component from the bottom of the first distillation column. The bottom liquid of the second distillation column is withdrawn, and the bottom liquid of the second distillation column is withdrawn, and at the same time, the diaryl oxalate vapor is withdrawn from the top of the second distillation column and recovered. It can also be done by.

In the first step of the present invention, as shown in FIG. 3, by-produced dialkyl oxalate and unreacted dialkyl oxalate extracted from the top of the second reactive distillation column 10 in the first step. And vapor containing a phenol compound as a main component are cooled to form a mixed liquid, circulated / supplied to the first reactive distillation column 1 for reuse, and the top part of the first distillation column 40 in the separation / purification. It is preferable that the condensate containing the alkylaryl oxalate and the phenol compound as main components recovered from the above is circulated and supplied to the second reactive distillation column 10 and reused.

The first reactive distillation column 1 and the second reactive distillation column 10 in FIGS. 2 and 3 are reactive distillation columns consisting of distillation columns having a large number of trays 2 or 12, or a packing material is filled in the upper part. It is preferable that the number of theoretical plates is at least 2 or more, especially 5 to 100.
It is preferably a multistage distillation column type reactive distillation column having 7 to 50 stages. Examples of the multi-stage distillation column type reactive distillation column include, for example, a tray-type distillation column type using a bubble cap tray, a perforated plate tray, a valve tray, or various types such as Raschig ring, Lessing ring, Pall ring and the like. A packed distillation column type packed with packing can be used, and further, a reactive distillation column having both a plate type and a packed type can also be used.

In the above-mentioned first step, the dialkyl oxalate, the phenol compound and the transesterification catalyst are separately or in the form of a mixed liquid, respectively, in the upper part of a large number of tray parts (or packing material parts) of the first reactive distillation column 1. It is preferable to supply the reaction solution to the zone to carry out the reaction, and the reaction liquid (canned liquid 3) extracted from the bottom of the first reactive distillation column 10 is also used in the second reactive distillation column 10.
It is preferable to carry out the reaction by feeding to the area above the tray portion (or the filler portion) of.

The transesterification catalyst used in the first step is, for example, an alkali metal compound, a cadmium compound, a zirconium compound, a lead compound, an iron compound, a copper group metal compound, a zinc compound, an organotin compound, or an aluminum compound. The soluble transesterification catalyst is preferably at least one selected from the group consisting of Lewis acid compounds, titanium Lewis acid compounds, and vanadium Lewis acid compounds.

Examples of the above-mentioned alkali metal compound, cadmium compound or zirconium compound include lithium carbonate, dibutylaminolithium, lithium acetylacetonate, cadmium bisacetylacetonate, zirconium tetrakisacetylacetonate and the like. Examples of the lead compound include lead sulfide, lead hydroxide, namalite, lead acid salt, lead carbonate or its basic salt, lead organic acid salt and its carbonate or basic salt, and tetrabutyl. Examples thereof include alkyl or aryl lead compounds such as lead, tetraphenyl lead, tributyl lead halogen, triphenyl lead bromine, and triphenyl lead, and alkoxy lead compounds such as dimethoxy lead, diethoxy lead, and methoxyphenoxy lead. Examples of the compound of the copper group metal include copper acetate, copper bisacetylacetonate, an organic acid salt of copper such as copper oleate, an alkyl copper compound such as butyl copper, an alkoxy copper compound such as dimethoxy copper, and a copper halide. And a silver compound such as silver nitrate, silver bromide, and silver picrate. Further, examples of the iron compound include iron compounds such as iron hydroxide, iron carbonate, triacetoxy iron, and trimethoxy iron, and examples of the zinc compound include zinc bisacetylacetonate, diacetoxy zinc, and dimethoxy zinc. , Diethoxyzinc, and the like.

As the above-mentioned organotin compound, for example,
(Ph) ₄ Sn, (AcO) ₄ Sn, (MeO) ₄ S
n, (EtO) ₄ Sn, (PhO) ₄ Sn, (Me) ₃
SnOAc, (Et) ₃ Sn (OAc), (Bu) ₃ S
n (OAc), (Et) ₃ Sn (OPh), (Me) ₃
SnOCOPh, (Ph) ₃ Sn (OMe), (Ph)
₃ SnOAc, (Bu) ₂ Sn (OAc) ₂ , (Bu)
₂ Sn (OMe) ₂ , (Bu) ₂ Sn (OEt) ₂ ,
(Bu) ₂ Sn (OPh) ₂ , (Bu) ₂ SnCl ₂ ,
(Ph) ₂ Sn (OMe) ₂ , (Bu) ₂ SnO, Bu
SnO (OH), (Et) ₃ SnOH, (Ph) ₃ Sn
OH etc. can be mentioned. However, Me is a methyl group, Et is an ethyl group, Bu is a butyl group, Ph is a phenyl group, and Ac is an acetyl group.

Examples of the above-mentioned Lewis acid compound of aluminum include AlX ₃ , Al (OAc) ₃ and Al (O
Me) ₃ , Al (OEt) ₃ , Al (OBu) ₃ , Al
(OPh) _{3 and the} like. Examples of the Lewis acid compound of titanium include TiX ₃ and Ti (O
Ac) ₃ , Ti (OMe) ₃ , Ti (OEt) ₃ , Ti
(OBu) ₃ , Ti (OPh) ₃ , TiX ₄ , Ti (O
Ac) ₄ , Ti (OMe) ₄ , Ti (OEt) ₄ , Ti
(OBu) ₄ , Ti (OPh) _{4 and the} like, and examples of the vanadium Lewis acid compound include VOX ₃ , VO (OAc) ₃ , VO (OM
e) ₃ , VO (OEt) ₃ , VO (OPh) ₃ , VX ₅
Can be mentioned. However, X shows a halogen atom.

In the production method of the present invention, the transesterification catalyst is preferably a lithium compound, a zirconium compound, an organic tin compound, a Lewis acid compound of titanium, and the like.
Among them, the organotin compound or the Lewis acid compound of titanium is most suitable.

The reaction in the above-mentioned first step (mainly the transesterification reaction of the reaction formula (2) and the disproportionation reaction of the reaction formula (4)) is carried out in a liquid state in which the reaction liquid is divided into the first reaction liquid and the first reaction liquid. When the reaction is carried out while flowing down the two-reaction distillation column, the reaction temperature is higher than the melting temperature of the reaction liquid consisting of the mixed liquid containing each raw material and the reaction product, and The temperature is preferably such that the product alkylaryl oxalate or diaryl oxalate does not thermally decompose. In the present invention, the reaction temperature in the transesterification reaction is about 50 to 300 ° C, particularly 100
The temperature is preferably about 250 to 250 ° C, more preferably about 120 to 230 ° C.

The reaction pressure of the reaction in the first step (mainly the reaction of the reaction formulas (2) and (4)) is reduced pressure,
Although it may be either atmospheric pressure or pressure, the temperature and pressure at which the by-product lower alcohol (mainly the first reactive distillation column) or dialkyl oxalate (mainly the second reactive distillation column) can be evaporated. Preferably. For example, the reaction temperature of the reaction in the first step is about 50-30.
At 0 ° C., the reaction pressure is 0.01 mmHg-10
0 kg / cm ² , especially 0.1 mmHg to 50 kg / cm
It is preferably about ² . Further, the reaction time of the reaction in the first step (mainly the reaction of the reaction formulas (2) and (4)) (in the case of using a reactive distillation column consisting of a multistage distillation column, the reaction time in the first and second reactive distillation columns) The residence time of the reaction solution)
Depending on the reaction conditions, the type of the reactive distillation column, the operating conditions, and the like, when the reaction temperature is about 50 to 300 ° C., about 0.01 to 50 hours, particularly 0.02 to 10 hours, and further 0.05 to It is preferably about 5 hours.

Although the ratio of the dialkyl oxalate to the phenol compound used in the first step varies depending on the kind and amount of the catalyst and the reaction conditions, the phenol compound is, for example, 0 relative to the dialkyl oxalate in the feedstock. 0.01 to 1000 times mol, particularly 0.1 to 100 times
It is preferable that the molar amount is twice, more preferably 0.5 to 20 times. The amount of the transesterification catalyst used in the first step varies depending on the type of catalyst, the type and size of the reaction apparatus, the type and composition of the raw materials, and the reaction conditions. For example, the total amount of the dialkyl oxalate and the phenol compound is Expressed as a ratio to the amount of about 0.0001 to 50% by weight, particularly 0.001 to 30% by weight, and further 0.005 to
It is preferably about 10% by weight.

In the second step of the present invention, a diaryl oxalate (C-
2), if necessary, in the presence of a CO removal catalyst,
By reacting, diaryl carbonate (e) and carbon monoxide (gas) are produced together.
Ar in the reaction formula (5) is the same as Ar described in the reaction formulas (2) to (4).

[0045]

[Chemical 3]

In the second step of the present invention, for example, the diaryl oxalate obtained in the first step is subjected to a CO deoxidation reaction in the presence of a phosphorus compound catalyst such as an organic phosphorus compound to produce a diaryl carbonate and a by-product. Carbon monoxide is produced, diaryl carbonate is separated and recovered from the reaction mixture, and carbon monoxide gas produced as a by-product is discharged to the outside of the reaction system.

As the catalyst used for the above CO removal reaction, the CO removal reaction of diaryl oxalate can be carried out at a relatively low temperature (about 100 to 350 ° C.), and the diaryl carbonate has a high selectivity (especially 60 to 100). Mol%) is preferable, and for example, an organic phosphorus compound having at least one carbon-phosphorus bond or the like can be used as the CO-free catalyst. Examples of such an organophosphorus compound include phosphine compounds (w) represented by general formulas (w) to (z), phosphine oxide compounds (x), phosphine dihalide compounds (y) and phosphonium salt compounds. Suitable examples include at least one organic phosphorus compound selected from (z).

[0048]

[Chemical 4]

[In the formula, R ^{1 to} R ¹³ are a hydrogen atom, an alkyl group having 1 to 16 carbon atoms, an aryl group having 6 to 20 carbon atoms,
And at least one substituent selected from an aralkyl group having 7 to 25 carbon atoms, X represents an atom or an atomic group capable of forming a counter ion, and Y ¹ and Y ² are independently a chlorine atom or a bromine atom. Represents a halogen atom such as iodine atom. At least one of the compounds (w) to (z) has the above-mentioned group other than a hydrogen atom. ]

The above-mentioned aryl group and aralkyl group each have a halogen atom such as a fluorine atom, a chlorine atom and a bromine atom, a nitro group, and a carbon number of 1 to 1 as a substituent which is directly bonded to the carbon forming the aromatic ring. At least 1 selected from 20 alkyl groups and alkoxy groups having 1 to 15 carbon atoms
Individual substituents may be attached.

Examples of the substituents of R ^{1 to} R ¹³ include an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group and an n-pentyl group, a phenyl group. Group, naphthyl group, methylphenyl group, ethylphenyl group, methoxyphenyl group, ethoxyphenyl group, chlorophenyl group, fluorophenyl group, methylnaphthyl group, methoxynaphthyl group, aryl group such as chloronaphthyl group, benzyl group, phenethyl group,
p-methylbenzyl group, p-methoxybenzyl group, p-
An aralkyl group such as a methylphenethyl group may be mentioned.

As the above-mentioned organic phosphorus compounds (w) to (z), it is preferable that all of the respective substituents (R ^{1 to} R ¹³ ) which they have are aryl groups, but the above organic phosphorus compounds are the same. 1 to 2 (especially 2) of the substituents may be aryl groups, and the rest may be alkyl groups or aralkyl groups.

Examples of the phosphine compound in which all of R ^{1 to} R ^{3 in} the general formula (w) are aryl groups include triphenylphosphine, tris (4-chlorophenyl) phosphine, tris (4-tolyl) phosphine, α Preferable examples thereof include -naphthyl (phenyl) -4-methoxyphenylphosphine. R ^{1 of} general formula (w)
Examples of the phosphine compound in which two R ^{3 s} are aryl groups include methyldiphenylphosphine and phenyl (p-methoxyphenyl) methylphosphine.

Examples of the phosphine oxide compound in which all of R ^{4 to} R ^{6 in} the general formula (x) are aryl groups include triphenylphosphine oxide, tris (4-chlorophenyl) phosphine oxide and tris (4-tolyl). Phosphine oxide, α-naphthyl (phenyl)-
4-methoxyphenylphosphine oxide can be preferably mentioned. Examples of the phosphine oxide compound in which two of R ^{4 to} R ^{6 in} the general formula (x) are aryl groups include methyldiphenylphosphine oxide and phenyl (p-methoxyphenyl) methylphosphine oxide.

Examples of the phosphine dihalide compound in which all of R ^{7 to} R ^{9 in} the general formula (y) are aryl groups include triphenylphosphine dichloride, triphenylphosphine dibromide, triphenylphosphine diiodide and the like. Can be mentioned.

In the phosphonium salt (z), all of R ^{10 to} R ^{13 in} the general formula (z) are aryl groups,
Moreover, a compound of a phosphonium salt in which the counter ion X ⁻ is a halogen ion, an aliphatic carboxylate ion, a fluoroborate or the like is preferable, and R ^{10 to} R ^{13 in the} general formula (z) are preferable.
1 to 3, especially 2 to 3 are aryl groups, the remainder is an aralkyl group or an alkyl group, and the counter ion X ⁻ is a halogen ion, an aliphatic carboxylate ion or a fluoroborate. It may be.

R ^{10 to} R ^{13 represented} by the above general formula (z)
Examples of the phosphonium salt (z) in which all are aryl groups include, for example, tetraphenylphosphonium chloride,
Tetraphenylphosphonium bromide, tetraphenylphosphonium iodide, 4-chlorophenyltriphenylphosphonium bromide, 4-chlorophenyltriphenylphosphonium bromide, 4-chlorophenyltriphenylphosphonium iodide, 4-ethoxyphenyltriphenylphosphonium chloride, 4-ethoxyphenyltri Phenylphosphonium bromide,
4-ethoxyphenyltriphenylphosphonium iodide, 4-methylphenyltriphenylphosphonium chloride, 4-methylphenyltriphenylphosphonium bromide, 4-methylphenyltriphenylphosphonium iodide, 9-fluorenylphenyltriphenylphosphonium chloride, 9 - fluorenyl phenyl triphenylphosphonium bromide, such as ^- and "counterion X phosphonium salt is a halogen ion", tetraphenylphosphonium acetate, 4-chlorophenyl triphenylphosphonium acetate, 4-ethoxyphenyl triphenylphosphonium acetate, 4- "Phosphonium salt whose counter ion X ^- is an aliphatic carboxylate ion" such as methylphenyltriphenylphosphonium acetate, "Phosphonium salt in which counter ion X ^- is fluoroborate" such as traphenylphosphonium fluoroborate, 4-chlorophenyltriphenylphosphonium fluoroborate, 4-ethoxyphenyltriphenylphosphonium fluoroborate, 4-methylphenyltriphenylphosphonium fluoroborate, etc. Can be mentioned.

The catalyst used in the CO removal reaction in the second step of the present invention may be an organic phosphorus compound alone or a mixture of two or more kinds. Further, those catalysts may be uniformly dissolved and / or suspended in the reaction solution. The amount of the catalyst used in the second step is 0.001 to 50 mol% based on the diaryl oxalate,
It is particularly preferably about 0.01 to 20 mol%.

[0059] the catalyst for removing CO reaction consisting of organophosphorus compounds of above, aluminum halides (aluminum chloride, aluminum bromide, etc.), a platinum group metal halides (chloroplatinic acid, ruthenium chloride, palladium chloride Etc.), inorganic halides such as phosphorus halides and sulfur halides, and at least organic halides such as halogenated hydrocarbons (alkyl halides, aralkyl halides, etc.) and halogen-substituted aliphatic carboxylic acids. One kind of halogen compound may be used together as a co-catalyst component. In that case, the amount of the co-catalyst used in combination is preferably about 0.01 to 150 times mol, particularly preferably about 0.1 to 100 times mol, of the organophosphorus compound.

In the CO removal reaction in the second step,
Diaryl oxalate and a catalyst containing an organic phosphorus-based compound as a main component are supplied to a CO-removing apparatus, and a reaction temperature of 10
0 to 450 ° C, especially 160 to 400 ° C, and further 180 to
At 350 ° C, while removing the generated carbon monoxide gas,
It is preferable to generate the diaryl carbonate by subjecting the diaryl oxalate to CO reaction. In this case, the reaction pressure may be reduced pressure, normal pressure or increased pressure, and is not particularly limited, but for example, 10 m
It may be in the range of mHg to 10 kg / cm ² . The CO removal reaction is preferably carried out in a liquid phase reaction, and no special solvent is required for the CO removal reaction,
If necessary, an aprotic polar solvent may be used in combination.

What kind of reactor can be used in the second step as long as it can carry out a CO removal reaction of diaryl oxalate in the presence of a CO removal catalyst if necessary to produce a diaryl carbonate together with CO gas. It can also be used in various types of reactors. The reactor (reactor) for the second step is, for example, a one-tank or multi-tank complete mixing reactor (stirring tank), a multitubular heat exchange tubular reactor, a tower reactor, etc. Can be mentioned. The material of the reactor is not particularly limited as long as it has sufficient heat resistance in the CO removal reaction, but examples thereof include glass (including lining), stainless steel (SUS), aluminum alloy, nickel alloy, zirconium. , Tantalum, etc. are used.

Since the reaction solution obtained by the CO removal reaction in the above-mentioned second step contains unreacted diaryl oxalate and CO removal catalyst, the diaryl carbonate is separated and purified from this reaction solution and recovered. The catalyst is separated by an evaporator such as an evaporator or thin film evaporator, and the distillation fraction is distilled using a distillation apparatus such as a packed column or a plate column having a certain number of theoretical plates (especially 5 to 50 plates). It is preferable to use the general method of Then, a highly pure diaryl carbonate can be obtained.

In the production method of the present invention, in the third step, for example, the diaryl carbonate obtained in the first step and the second step is subjected to a polycondensation reaction to separate and collect the by-product phenol compound. While producing a polycarbonate, the recovered phenol compound is distilled and purified if necessary to remove high-boiling fractions (high-boiling impurities). Polycarbonate is produced by supplying it to the process and reusing it in the reaction of the first step.

The above-mentioned polyhydric hydroxy compound is mainly composed of an aromatic polyhydric hydroxy compound in which a plurality (particularly two) of hydroxy groups are directly bonded to the aromatic ring of the aromatic compound. . In particular, all of the polyhydric hydroxy compounds are aromatic dihydric hydroxy compounds, or 60 mol% or more, especially 80
The aromatic divalent hydroxy compound may be blended in an amount of ˜100 mol%. As such a polyvalent hydroxy compound, for example, the total amount of the polyvalent hydroxy compound is 2,2-bis (4-hydroxyphenyl) propane or 2,2-bis (4-hydroxyphenyl) propane is 80. ~ 100 mol%, preferably 90 ~
Examples thereof include polyhydric hydroxy compounds blended at a ratio of 100 mol%.

The above-mentioned polyhydric hydroxy compound is an aliphatic hydrocarbon-based polyhydric hydroxy compound having two or more hydroxy groups (for example, aliphatic diol compounds such as ethylene glycol, propylene glycol, butanediol and hexanediol). ) May be partially used in combination with the above-mentioned aromatic polyhydric hydroxy compound.

Specific examples of the aromatic polyhydric hydroxy compound include bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane,
2,2-bis (4-hydroxyphenyl) propane,
2,2-bis (4-hydroxyphenyl) butane, 2,
2-bis (4-hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, 2,2-
Bis (4-hydroxy-2-methylphenyl) propane, 1,1-bis (4-hydroxy-2-t-butylphenyl) propane, 2,2-bis (4-hydroxy-3)
Bis (hydroxyaryl) alkanes such as -bromophenyl) propane [the above compounds are also called bisphenol compounds], 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dimethyldiphenyl ether, etc. Dihydroxyaryl ethers, dihydroxyaryl sulfides such as 4,4′-dihydroxydiphenyl sulfide and 4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfide, 4,4′-dihydroxydiphenyl sulfoxide, 4, Dihydroxy aryl sulfoxides such as 4′-dihydroxy-3,3′-dimethyldiphenyl sulfoxide, and dihydroxy aryl sulfoxides such as 4,4′-dihydroxydiphenyl sulfone and 4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfone. And aryl sulfones and the like.

Examples of the diaryl carbonate include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, bis (m-cresyl) carbonate, dinaphthylcarbonate and the like. Among these, diaryl carbonates having 13 to 20 carbon atoms are preferable,
Diphenyl carbonate is particularly preferable.

Further, these diaryl carbonates may contain dicarboxylic acid esters. Examples of such dicarboxylic acid esters include aromatic carboxylic acid diesters such as diphenyl terephthalate and diphenyl isophthalate. In the present invention, when the diaryl carbonate and the above-mentioned dicarboxylic acid ester are used in combination, a polyester carbonate is obtained, but in the present invention, the polyester carbonate may be produced as the polycarbonate.

When the polycarbonate is produced in the third step of the present invention, the diaryl carbonate as described above is used in an amount of 1 mol based on 1 mol of the polyvalent hydroxy compound (divalent hydroxy compound, particularly aromatic divalent hydroxy compound). It is preferably used in an amount of 0.001 to 1.5 mol, particularly 1.01 to 1.3 mol. In addition, in the third step, in addition to the diaryl carbonate and the polyhydric hydroxy compound, an appropriate polymerization regulator, terminal modifier, monophenol, etc. may be used in combination.

In the third step of the present invention, the diaryl carbonate and the polyvalent hydroxy compound are mixed with a suitable basic catalyst (for example, an organic acid salt of an alkali metal or an alkaline earth metal, an inorganic acid salt, a hydroxide, hydrogen). Compound, alcoholate, or nitrogen-containing basic compound) at a temperature of about 100 to 330 ° C. while evaporating and removing the by-produced phenol compound, and gradually increasing the polymerization temperature and reducing the pressure. It is preferable that the polycarbonate is produced by melt polymerization in one step or two or more steps while increasing the temperature.

Examples of the basic catalyst include, for example,
(1) Ammonium hydroxides having an alkyl, aryl or aralkyl group (for example, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide,
Trimethylbenzylammonium hydroxide, etc.), tertiary amines (eg, trimethylamine, triethylamine, dimethylbenzylamine, triphenylamine, etc.), secondary amines, primary amines, tetramethylammonium borohydride, tetrabutylammonium borohydride, etc. Nitrogen-containing basic compounds, (2) Alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate , Sodium dihydrogen phosphate,
Inorganic acids of alkali metals such as kalim dihydrogen phosphate, lithium dihydrogen phosphate, sodium dihydrogen phosphite, potassium dihydrogen phosphite, disodium hydrogen phosphate, dipotassium hydrogen phosphate and dilithium hydrogen phosphate. Salts, organic acid salts of alkali metals such as sodium acetate, potassium acetate, lithium acetate, sodium stearate, sodium benzoate, hydrides of alkali metals such as sodium borohydride, alkali metal alcoholates such as sodium salt of phenol, (3) Hydroxides of alkaline earth metals such as calcium hydroxide, barium hydroxide, magnesium hydroxide and strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, calcium carbonate, barium carbonate, magnesium carbonate, Alkals such as strontium carbonate Inorganic acid salts of alkaline earth metals, calcium acetate, barium acetate, barium stearate, can be given alone or the combined catalyst such as alkaline earth metal organic acid salts such as magnesium stearate.

The above basic catalyst can be used in combination with boric acid or boric acid ester. Examples of the borate ester include trimethyl borate, triethyl borate, tributyl borate, trihexyl borate, triphenyl borate, and tritolyl borate.

In the third step of the present invention, the amount of the basic catalyst used is 10 ^-8 to 10 mol per 1 mol of the polyvalent hydroxy compound (particularly aromatic divalent hydroxy compound) used in the condensation polymerization reaction. It is preferably 10 ⁻¹ mol, particularly 10 ⁻⁷ to 10 ⁻² mol.

The polycondensation reaction in the third step of the present invention comprises
The polycondensation reaction can be carried out under the same conditions as the condensation polymerization reaction conditions in the conventionally known polycarbonate production method, but in particular, in the first step, a polyvalent hydroxy compound (particularly an aromatic divalent hydroxy compound) and a diaryl carbonate are used. Polycondensation reaction with 80-250 ° C., especially 100-230
C., further 150 to 200.degree. C., 0.01 to 5 hours, especially 0.0 to 4 hours, further 0.25 to 3 hours, near atmospheric pressure or under reduced pressure, then the second stage The second polycondensation reaction is carried out at a higher reaction temperature and reduced pressure than those in the first step, and finally 240 to 32 under reduced pressure of 1 mmHg or less.
It is preferred to carry out at a temperature of 0 ° C.

The polycondensation reaction may be carried out continuously or batchwise. The reactor used in the above-mentioned polycondensation reaction may be a tank reactor or a tubular reactor (especially, a self-cleaning reactor is preferable for the second-stage polycondensation). It may be a type reactor.

Then, in the third step of the present invention, the phenol compound by-produced in the condensation polymerization reaction is evaporated and separated, and the separated phenol compound is refined (for example, an evaporator and a distillation apparatus). Refined by
A purified phenol compound can be obtained. The purified phenol compound has a content of other organic impurities (in particular, an organic compound having a higher boiling point than that of the phenol compound) of about 50.
0 ppm or less, particularly 200 ppm or less, and further 0.01
It may be about 100 ppm.

Specifically, the phenol compound by-produced in the polycondensation reaction of the third step of the present invention is evaporated and separated, and the separated phenol compound (recovered phenol compound) is removed by an evaporator, a distillation column or the like. Purified (especially phenol compound liquid (container liquid) containing high-boiling point impurities in high concentration)
About 5 to 20% by weight based on the total recovered phenolic compound,
It is preferable to obtain a purified phenol compound that has been evaporated or distilled and purified by removing about 6 to 15% by weight), supply the purified phenol compound to the first step and reuse it in the reaction of the first step. The phenol compound containing the high-boiling-point organic impurities can be further purified before use.

Therefore, in the third step of the present invention, a purification apparatus (for example, a distillation apparatus) for purifying the phenol compound and a purified phenol compound (purified phenol compound) are used in the above-mentioned first step. Means for intermittently or continuously supplying to a reaction reactor (eg, first reactive distillation column) of the reaction (eg, transport pump and piping to the first step, or relay tank for purified phenol compound, transport pump, and first pump) It is preferable to use a polycondensation reactor equipped with a pipe to the process.

The polycarbonate obtained in the present invention is obtained by polycondensation using a diaryl carbonate such as diphenyl carbonate obtained in the above-mentioned first step and second step and containing few impurities that affect the polycondensation. It is characteristic that it is a thing. In the production method, it is possible to employ polymerization conditions such as melt polymerization which are almost the same as the production methods of other polycarbonates, and the known polycondensation method (for example,
The same high molecular weight (10,000 to 80,000) as that of a general polycarbonate obtained by the melt polymerization method can be achieved, and at the same time as for other polymer physical properties, the same high level as a general polycarbonate can be achieved. In addition, it is possible to obtain a polycarbonate that has almost no coloring. The polycarbonate obtained by the present invention is industrially highly valuable.

[0080]

EXAMPLES Examples of the present invention are shown below. The analysis of the reaction solution and the like was performed by gas chromatography. Example 1 [First Step: Production of Diphenyloxalate] Using a production process as shown in FIG. 3 (one distillation column), dimethyloxalate was used to produce diphenyloxalate as follows. did. Phenol 54.1% by weight, dimethyl oxalate 45.3% by weight at the 12th plate from the top of the Oldershaw (first reactive distillation column) having an inner diameter of 32 mm and 50 plates, equipped with a 1-liter bottom flask, A mixture containing 0.5% by weight of tetraphenoxytitanium was supplied at 600 ml / hour (hr), the bottom flask was heated to 190 ° C. with a mantle heater, and the vapor from the top of the tower was condensed with a cooler. Reflux ratio 2
The reaction (transesterification reaction) was performed while extracting with. When the state of the first reactive distillation column became stable (4 hours after starting the supply), the composition of the bottom liquid was 6.23% by weight of diphenyl oxalate and 2 parts of methyl phenyl oxalate.
The amount was 9.95% by weight, dimethyloxalate 23.88% by weight, and phenol 39.41% by weight, and the amount of extraction was about 603 g / hr. At this time, a condensate having a composition of 99.7% by weight of methanol and 0.3% by weight of dimethyl oxalate was withdrawn from the top of the column at a rate of about 44 g / hr.

Bottom liquid (can liquid) of this transesterification reaction
At the 12th stage from the top of the Oldershaw (second reactive distillation column) of the same type as described above, under a reduced pressure of 200 mmHg,
While supplying 600 ml / hr, the bottom flask is heated to 200 ° C. by the mantle heater, the vapor from the top of the tower is condensed by the cooler, and the reaction (disproportionation reaction) is carried out while withdrawing it without reflux. It was When the state of the second reactive distillation column became stable (4 hours after starting the supply), the composition of the column bottom liquid (container liquid) was 65.27% by weight of diphenyl oxalate and 1 part of methyl phenyl oxalate.
It was 8.43% by weight, 1.02% by weight of dimethyl oxalate, and 13.93% by weight of phenol, and the extracted amount was about 258 g / hr. Further, at this time, from the top of the tower, 1.57% by weight of methanol, 2.97% by weight of dimethyl oxalate, 48.51% by weight of phenol, 2.97% by weight of methylphenyl oxalate, 0.42% by weight of diphenyl oxalate. % Condensate of about 371
Extracted at g / hr.

The bottom liquid (can liquid) of this disproportionation reaction was fed to a rotary thin film evaporator having a heat transfer area of 0.1 m ² at a reduced pressure of 15 mmHg and at a rate of 200 ml / hr.
The evaporator was heated to 200 ° C. with a heating medium to continuously evaporate dimethyl oxalate, phenol, methylphenyl oxalate and diphenyl oxalate. The vapor obtained was filled with a 5 × 5 mm helipack, and the inside diameter was 30 m.
It was fed to a position of 80 cm from the top of a glass distillation column having a length of m and a length of 2 m, and continuously distilled. Then, from the top of the distillation column, 3.05% by weight of dimethyl oxalate,
A condensate having a composition of 41.73% by weight of phenol and 55.21% by weight of methylphenyl oxalate was withdrawn at about 68 ml / hr, and diphenyl oxalate having a purity of 99.9% by weight was obtained from a position 40 cm above the bottom of the column. It was extracted at about 120 g / hr. As impurities in the extracted diphenyl oxalate, phenol was 0.04% by weight and methylphenyl oxalate was 0.0
It was 5% by weight. Also, about 2.5 from the bottom of the evaporator
Approximately 14 g / hr of liquid containing titanium by weight (metal equivalent)
I pulled it out.

[Second Step: Production of Diphenyl Carbonate] Using the diphenyl oxalate obtained in the above reaction, diphenyl carbonate was produced as follows. 1 mol% of tetraphenylphosphonium chloride was added to diphenyl oxalate and heated to 150 ° C. to dissolve. This solution was supplied at a rate of 300 ml / hr using a metering pump to a reactor in which two glass reactors each having an internal volume of 1 liter and equipped with a thermometer, a stirrer and an overflow pipe were connected in series, and two The reactor was heated by a mantle heater and maintained at 230 ° C. to carry out the CO removal reaction of diphenyl oxalate. The overflow position of each reactor was 600 ml.

Twenty hours after the start of the supply of the raw materials, the composition of the overflow liquid (reaction liquid for the CO removal reaction) in the second reactor was 14.6% by weight of diphenyl oxalate, 84.0% by weight of diphenyl carbonate and 0% of phenol. 0.08% by weight, and the withdrawal amount is about 270 ml /
It was hr. The composition of the gas generated from each reactor was about 100% carbon monoxide, and the total amount of carbon monoxide recovered was 25 liters (standard state) / hr.

20 m of the reaction solution of this CO removal reaction was put in a rotary thin film evaporator similar to the separation and purification of the reaction solution in the first step.
While supplying at 250 ml / hr under reduced pressure of mHg, the evaporator was heated to 200 ° C. with a heating medium to separate tetraphenylphosphonium chloride. The obtained distillate (composition: diphenyl carbonate 92.2% by weight,
Diphenyl oxalate (7.7% by weight) was supplied to a glass distillation column similar to the one used in the separation and purification of the reaction solution in the first step to continuously distill it (column top pressure: 20 torr, reflux ratio:
5), diphenyl carbonate with a purity of 99.9% is about 2
Obtained at 20 ml / hr.

[Third Step: Production of Polycarbonate (A
Method)] 400 g of bisphenol A, 800 ml of toluene and 36 ml of ethanol (volume ratio:
It was recrystallized from a mixed solvent of 22/1) to obtain a purified product of bisphenol A. As the diphenyl carbonate, the one obtained as described above was used as it was. In addition, potassium dihydrogen phosphate (purity: 99.99%) 0.6815
g in 50 ml of ion-exchanged water, and a concentration of 0.1 mol / liter polymerization catalyst solution (pH: 4.
35) was prepared.

10 made of stainless steel (SUS316L)
Bisphenol A (purified product) in a 0 ml reactor
22.83 g (0.1 mol), 22.71 g (0.106 mol) of diphenyl carbonate, and 0.03 ml of a 0.1 mol / l polymerization catalyst solution (5 ppm as K metal with respect to bisphenol A) were added. Then, vacuum deaeration in the reactor was carried out at room temperature for 0.5 hour, then nitrogen gas was introduced to return the reaction system to normal pressure, and then the reactor was heated to carry out the polycondensation reaction. That is, after heating at 200 ° C. for 10 minutes and 230 ° C. for 10 minutes, decompression was started at 230 ° C., phenol distillation started at 230 ° C. and 100 torr for 1 hour, and then 240 ° C. and 100 torr.
reaction for 0.5 hours at r.
The temperature was maintained at 0 torr for 10 minutes, and the pressure was reduced from 100 torr to 50 torr in 15 minutes, and then the pressure was maintained for 15 minutes to allow reaction.
The pressure was reduced from r to 0.1 torr in 30 minutes, and the state was maintained for 1 hour for reaction. As a result, 25.44 g of polycarbonate (yield: 100%) was obtained.

The polycarbonate obtained had an inherent viscosity of 0.4 (unit: dl / g, concentration: 0.5 g / 100 ml, solvent: CHCl ₃ , measurement temperature: 30 ° C.).
It was 97 dl / g and its weight average molecular weight (polystyrene conversion method) was 53,000. The polycarbonate was visually almost colorless.

In the above polycondensation reaction, a total of 17.
6 milliliters of phenol were recovered. The recovered phenol was distilled and purified in a distillation column to remove about 10% by weight of a residual fraction (container liquid) containing impurities having a high boiling point to obtain a purified and purified phenol by distillation. The purified phenol had an organic compound-based impurity of 10 ppm or less and was a high-purity product containing substantially no other components. The purified phenol was directly supplied to the first reactive distillation column of the first step and used together with other fresh phenol, but the reaction of the first step could be carried out without any trouble.

Example 2 [First Step: Production of Diphenyl Oxalate] Example 1
The reaction in the first step was carried out in the same manner as in the production of diphenyl oxalate of Example 1 to obtain diphenyl oxalate having a purity of 99.6% by weight at about 120 g / hr.

[Second Step: Production of Diphenyl Carbonate] The CO removal reaction was carried out for 24 hours in the same manner as in Example 1 except that the diphenyl oxalate obtained in the above first step was used, and the purity was 99.9. % Diphenyl carbonate was obtained at about 220 ml / hr.

[Third Step: Production of Polycarbonate (B
Method)] in a tank reactor (nickel metal alloy-clad),
2,2-bis (4-hydroxyphenyl) propane 20
Mol, 21 mol of diphenyl carbonate obtained in the above second step, and potassium dihydrogen phosphate (purity: 99.
(99%) 6 mol of 0.1 mol / liter solution was added, and the mixture was melted at 160 ° C. under nitrogen, stirred for 1 hour, and gradually heated under reduced pressure. And finally 1 torr,
A polycondensation reaction is carried out at 270 ° C for 4 hours, while a byproduct phenol is evaporated and recovered to form a polycarbonate prepolymer, and finally a vertical biaxial self-cleaning reactor is run at 270 ° C and 0.1 torr for 50 minutes. By doing so, colorless transparent polycarbonate (molecular weight: about 55000) was extruded.

The total amount of phenol recovered in the above polycondensation reaction was about 3760 g. The recovered phenol was purified by distillation in a distillation column to remove about 10% by weight of a residual fraction (container liquid) containing impurities having a high boiling point, to obtain purified phenol purified by distillation. The purified phenol had an organic compound-based impurity of 10 ppm or less and was a high-purity product containing substantially no other components. The purified phenol was directly supplied to the first reactive distillation column of the above-mentioned first step and used together with other fresh phenol.
The reaction in the first step could be carried out without any trouble.

[0094]

INDUSTRIAL APPLICABILITY In the present invention, a dialkyl oxalate is reacted with a phenol compound to produce a diaryl oxalate, and then the diaryl oxalate is de-CO 2
Reacting to produce a diaryl carbonate, and further,
A polycondensation reaction of the diaryl carbonate and a polyhydric hydroxy compound is performed to form a polycarbonate, and a by-product phenol compound is separated and recovered and reused in the first reaction between the dialkyl oxalate and the phenol compound. It is possible to solve the problems in the method for producing a diaryl carbonate such as diphenyl carbonate by the phosgene method or the non-phosgene method. Then, an industrial method for producing a polycarbonate by a polycondensation method (for example, a melt polymerization method) using a diaryl carbonate such as diphenyl carbonate obtained by a new production method from a dialkyl oxalate via a diaryl oxalate is provided. It is to be.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a manufacturing process of the present invention.

FIG. 2 is a diagram showing an example of a first step (production of diaryl oxalate) in the production method of the present invention.

FIG. 3 is a diagram showing an example of a first step (production of diaryl oxalate) in the production method of the present invention.

[Explanation of symbols]

1: First Reactive Distillation Tower 2: Shelf 3: Can Liquid (Reaction Liquid) 4: Raw Material Supply Line 10: Second Reactive Distillation Tower 12: Shelf 13: Can Liquid (Reaction Liquid) 20: Distillation Column (or No. 2 Distillation tower) 21: Product (diaryl carbonate) extraction line 22: Shelf 23: Can liquid 30: Evaporator 33: Can liquid 40: Distillation tower (first distillation tower) 43: Can liquid

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Yoshinori Shiotani, 8-1 Goiminamikaigan, Ichihara-shi, Chiba Ube Industries, Ltd., Polymer Research Laboratory (72) Inventor, Washio Victory, Ichihara-shi, Chibaken, 8th No. 1 Ube Kosan Co., Ltd., Polymer Research Laboratory (56) Reference JP-A-10-59905 (JP, A) JP-A-6-263694 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 69/96 C08G 64/00-64/42

Claims (13)

(57) [Claims] 1. In the first step, a dialkyl oxalate is reacted with a phenol compound to produce a diaryl oxalate, and in the second step, the diaryl oxalate is de-CO-reacted to carry out mono-oxidation of the diaryl carbonate and a by-product. Carbon is generated, and in the third step, the diaryl carbonate and the polyvalent hydroxy compound are subjected to polycondensation reaction to separate and collect the by-product phenol compound to form a polycarbonate. A method for producing a polycarbonate characterized in that it is circulated and supplied to the first step and reused in the reaction of the first step. 2. In the first step, the dialkyl oxalate and the phenol compound are reacted in the presence of a transesterification catalyst while removing the lower alcohol produced outside the reaction system to produce and separate diaryl oxalate. The method for producing a polycarbonate according to claim 1. 3. The unreacted dialkyl oxalate and the phenol compound in the first step are simultaneously or separately separated and recovered, and the dialkyl oxalate and the phenol compound are circulated / supplied to the first step to react in the first step. The method for producing a polycarbonate according to claim 1, wherein the polycarbonate is reused. 4. The reaction in the first step is carried out by transesterification of dialkyl oxalate and a phenol compound in the presence of a transesterification catalyst while removing the lower alcohol produced out of the reaction system to give an alkylaryl oxalate. 2. The polycarbonate according to claim 1, which is produced by subjecting the alkylaryl oxalate to a disproportionation reaction in the presence of the catalyst while removing the dialkyl oxalate that is produced to produce a diaryl oxalate. Manufacturing method. 5. The dialkyl oxalate produced in the disproportionation reaction in the first step is separated and recovered, and the dialkyl oxalate is circulated / supplied to the first step and reused in the transesterification reaction in the first step. The method for producing the polycarbonate according to claim 4. 6. The method according to claim 1, wherein the reaction of the first step is carried out in the presence of a transesterification catalyst containing a Lewis acid compound of titanium.
Alternatively, the method for producing the polycarbonate according to 4 above. 7. The method for producing a polycarbonate according to claim 1, wherein the phenol compound in the first step is phenol. 8. The method for producing a polycarbonate according to claim 1, wherein the diaryl carbonate produced in the CO removal reaction of the second step is separated, purified and recovered. 9. The method for producing a polycarbonate according to claim 1, wherein carbon monoxide by-produced in the CO removal reaction of the second step is recovered in a gaseous state. 10. The method for producing a polycarbonate according to claim 1, wherein the CO removal reaction in the second step is carried out in the liquid phase in the presence of a phosphorus compound catalyst. 11. The method for producing a polycarbonate according to claim 1, wherein the polycondensation reaction in the third step is carried out in the presence of a basic catalyst. 12. The method for producing a polycarbonate according to claim 1, wherein the polyvalent hydroxy compound in the third step is an aromatic divalent hydroxy compound. 13. The method for producing a polycarbonate according to claim 1, wherein the polyhydric hydroxy compound in the third step is a bisphenol compound.