JP2016185524A - Recovery method of catalyst, production method of diphenyl carbonate using the recovered catalyst, and production method of polycarbonate using the diphenyl carbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reuse a catalyst recovered from a reaction liquid and to reuse a solvent used for recovering the catalyst, when tetraarylphosphonium halide and/or an adduct of tetraarylphosphonium halide and hydrogen halide are used as the catalyst in a production of diphenyl carbonate by a decarbonylation reaction of diphenyl oxalate.SOLUTION: In recovering a catalyst which is tetraarylphosphonium halide and/or an adduct of tetraarylphosphonium halide and hydrogen halide, and which is included in a residual liquid remaining after acquiring a component including diphenyl carbonate from a reaction liquid after a decarbonylation reaction, the recovery method of the catalyst has a step to bring the residual liquid into contact with a polar organic solvent and hydrogen chloride, and a step to recover the polar organic solvent used in the catalyst recovery and reuse it in the catalyst recovery step.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing diphenyl carbonate. Specifically, in the case of using tetraarylphosphonium halide and / or an adduct of tetraarylphosphonium halide and hydrogen halide as a catalyst for the production of diphenyl carbonate by decarbonylation reaction of diphenyl oxalate, the catalyst recovered from the reaction solution And a solvent used for catalyst recovery is also reused to efficiently and efficiently produce high-purity diphenyl carbonate by a simple method.

Carbonic acid diesters are known as raw material compounds in various chemical reactions. In particular, it is known that diphenyl carbonate can produce a polycarbonate by a polycondensation reaction with a divalent hydroxyaromatic compound.
As a method for producing a carbonic acid diester, a method in which phosgene and an aromatic hydroxy compound are reacted in the presence of an alkali is known. However, since phosgene itself is a highly toxic compound and requires a large amount of alkali, there is also a method for producing a carbonic acid diester by decarbonylating a oxalic acid diester in the presence of a decarbonylation catalyst such as an organophosphorus compound. It has been proposed (see Patent Document 1). In addition, the phosphonium salt catalyst used in the decarbonylation reaction is expressed as follows: “By adding an organic polar solvent to the reaction mixture for dilution and adding a hydrogen halide, the phosphonium salt remaining in the reaction mixture or A method of recovering by precipitating and separating the phosphonium salt component as a hydrogen halide adduct has also been proposed (see Patent Document 2).

JP-A-8-333307 JP 2002-45704 A

  However, the above catalyst recovery method cannot always efficiently recover a high-purity catalyst, and further improvement has been demanded. Moreover, although the organic polar solvent used for collection contains hydrogen halide and water, it has not been studied at all about collecting and reusing this. Accordingly, the problem of the present invention is that when a tetraarylphosphonium halide and / or an adduct of a tetraarylphosphonium halide and a hydrogen halide is used as a catalyst in the production of diphenyl carbonate by decarbonylation of diphenyl oxalate, To provide a method for stably and efficiently producing high-purity diphenyl carbonate by reusing and reusing a high-purity catalyst efficiently by the method and also reusing the solvent used for catalyst recovery. And

  In order to solve the above-mentioned problems, the present inventor has intensively studied a method for recovering a tetraarylphosphonium halide and / or an adduct of a tetraarylphosphonium halide and a hydrogen halide. As a result, a highly pure catalyst can be efficiently recovered by contacting a polar organic solvent with hydrogen chloride gas and / or hydrochloric acid to the residual liquid obtained from the reaction liquid containing a component containing diphenyl carbonate. It has been found that the above problem can be solved by reusing the residual liquid after catalyst recovery as the polar organic solvent.

  That is, the first gist of the present invention is a method for recovering a catalyst used for production of diphenyl carbonate by decarbonylation reaction of diphenyl oxalate, wherein the catalyst is tetraarylphosphonium halide and / or tetraarylphosphonium halide and halogen. The adduct body with hydrogen fluoride is obtained by bringing the residual liquid obtained from the reaction liquid after the decarbonylation reaction into contact with a polar organic solvent and hydrogen chloride, and then collecting the catalyst contained in the residual liquid. (Catalyst recovery step) and the polar organic solvent is recovered and reused in the catalyst recovery step. The second gist of the present invention is the catalyst recovery method described in the first gist, wherein the polar organic solvent used in the catalyst recovery is subjected to the following steps (A) and (B) in this order. In the method of recovering the catalyst, the catalyst is reused after being purified. (A) Step: The polar organic solvent used for the catalyst recovery is evaporated and distilled into a liquid-liquid separator containing water, and the polar organic solvent phase of the liquid-liquid separator is moved to the residual liquid side. A step of removing at least a part of hydrogen chloride contained in the residual liquid by returning, a step (B): a step of distilling the liquid obtained in the step (A).

A third aspect of the present invention is a method for recovering a catalyst according to the first or second aspect, wherein the catalyst is an adduct of an asymmetric tetraarylphosphonium halide and / or an asymmetric tetraarylphosphonium halide and a hydrogen halide. The method resides in a method for recovering a catalyst.
A fourth aspect of the present invention is the catalyst recovery method according to any one of the first to third aspects, wherein the residual liquid is contacted with a polar organic solvent and hydrogen chloride. The catalyst recovery method is characterized by contacting with an organic solvent and then with hydrogen chloride. A fifth aspect of the present invention is the catalyst recovery method according to any one of the first to third aspects, wherein the contact of the polar organic solvent and hydrogen chloride with the residual liquid is performed with the polar organic solvent. After contacting with the hydrogen chloride, the residual liquid is brought into contact with the hydrogen chloride.

  The sixth aspect of the present invention is a method for producing diphenyl carbonate by decarbonylation of diphenyl oxalate, which is recovered as a catalyst by the recovery method according to any one of the first to fifth aspects. It exists in the manufacturing method of diphenyl carbonate characterized by using a precipitate. The seventh gist of the present invention is a continuous production method of diphenyl carbonate having a step of decarbonylating diphenyl oxalate, which comprises the following first to fourth steps in this order. It is a continuous manufacturing method. First step: a step of producing diphenyl carbonate by decarbonylation reaction of diphenyl oxalate in the presence of tetraarylphosphonium halide and / or an adduct of tetraarylphosphonium halide and hydrogen halide, second step: first A step of separating a component containing diphenyl carbonate from the reaction liquid obtained in the step, a third step: a step of precipitating the catalyst contained in the residual liquid from which the component containing diphenyl carbonate was separated in the second step (here, the third step The step includes a step of bringing a polar organic solvent and hydrogen chloride into contact with at least a portion of the residual liquid), and a fourth step: at least a portion of the precipitate obtained in the third step is decarbonylated in the first step. Supplying as a catalyst.

  An eighth aspect of the present invention is a process for producing a polycarbonate by polycondensation of diphenyl carbonate and a dihydroxy compound in the presence of a transesterification catalyst, wherein the diphenyl carbonate is described in the sixth aspect. The present invention resides in a method for producing a polycarbonate, which is produced by the method for producing diphenyl carbonate or the continuous production method for diphenyl carbonate described in the seventh aspect and then polycondensed with the dihydroxy compound.

According to the present invention, when an adduct of tetraarylphosphonium halide and / or tetraarylphosphonium halide and hydrogen halide is used as a catalyst for the production of diphenyl carbonate by decarbonylation of diphenyl oxalate, By this method, high-purity diphenyl carbonate can be efficiently and stably produced by recovering and reusing the high-purity catalyst efficiently and reusing the solvent used for catalyst recovery. Further, by using this high purity diphenyl carbonate as a raw material, a high purity polycarbonate can be obtained.

Hereinafter, embodiments of a method for recovering a catalyst of the present invention, a method for manufacturing diphenyl carbonate using the recovered catalyst, and a method for manufacturing a polycarbonate using the diphenyl carbonate will be described in detail.
The catalyst recovery method of the present invention was used for the production of diphenyl carbonate by the decarbonylation reaction of diphenyl oxalate (hereinafter sometimes referred to as “decarbonylation reaction according to the present invention” or simply “decarbonylation reaction”). The catalyst and the solvent used for catalyst recovery are recovered. Moreover, in the manufacturing method of diphenyl carbonate of this invention, diphenyl carbonate is obtained by carrying out decarbonylation reaction of diphenyl oxalate using this collect | recovered catalyst.
The decarbonylation reaction according to the present invention is performed according to the following reaction formula (1).

(In the formula, Ph represents a phenyl group.)

[Diphenyl oxalate]
In the method for producing diphenyl carbonate of the present invention, diphenyl oxalate (hereinafter sometimes referred to as “diphenyl oxalate according to the present invention” or simply “diphenyl oxalate”) is diphenyl carbonate (hereinafter referred to as “according to the present invention”). It may be referred to as “diphenyl carbonate” or simply “diphenyl carbonate”. The diphenyl carbonate according to the present invention obtained from the diphenyl oxalate according to the present invention as a raw material is thermally stable and suitable as a raw material for polycarbonate.

  As diphenyl oxalate, one produced by transesterification of dialkyl oxalate and phenol as shown in the following reaction formula (2) can be used. Here, as the dialkyl oxalate used as a raw material, as produced by the following reaction formula (3), those produced by an carbonylation reaction using carbon monoxide, oxygen and an aliphatic alcohol as raw materials can be used.

(In the formula, R represents an alkyl group, and Ph represents a phenyl group.)

(In the formula, R represents an alkyl group.)
[catalyst]
The catalyst used in the method for producing diphenyl carbonate of the present invention is supplied to the reactor as an adduct of tetraarylphosphonium halide and / or tetraarylphosphonium halide and hydrogen halide. The tetraarylphosphonium halide is referred to as “tetraarylphosphonium halide according to the present invention” or simply “tetraarylphosphonium halide”, and the hydrogen halide is referred to as “hydrogen halide according to the present invention” or simply “hydrogen halide”. The adduct body may be referred to as “the adduct body according to the present invention” or simply “the adduct body”.

  The tetraarylphosphonium halide according to the present invention is a compound represented by the following general formula (4).

(In the formula, Ar ¹ , Ar ² , Ar ³ and Ar ⁴ each independently represent an aromatic ring group which may have a substituent, and X represents a halogen atom.)
As the aromatic ring group of Ar ^{1 to} Ar ^4, an aromatic hydrocarbon group having 6 to 14 carbon atoms such as a phenyl group, a biphenyl group, and a naphthyl group, a sulfur atom such as a thienyl group, a furyl group, and a pyridyl group, an oxygen atom, or Examples thereof include an aromatic heterocyclic group having 4 to 16 carbon atoms containing a nitrogen atom. Of these, an aromatic hydrocarbon group is preferable because a catalyst can be produced at low cost, and a phenyl group is more preferable.

Ar ^{1 to} Ar ⁴ include various isomers, and each aromatic ring group may have one or more substituents. Examples of the substituent include an alkyl group (preferably 1 to 12 carbon atoms), an alkoxy group (preferably 1 to 12 carbon atoms), a thioalkoxy group (preferably 1 to 12 carbon atoms), an aralkyloxy group (preferably Has 7 to 13 carbon atoms, aryloxy group (preferably 6 to 16 carbon atoms), thioaryloxy group (preferably 6 to 16 carbon atoms), acyl group (preferably 1 to 12 carbon atoms), alkoxycarbonyl group (Preferably 2 to 16 carbon atoms), carboxyl group, amino group, alkyl-substituted amino group (preferably 2 to 16 carbon atoms), nitro group, cyano group, hydroxy group, halogen atom (fluorine, chlorine, bromine, etc.), etc. Is mentioned. Further, these substituents may further have a substituent, and examples of the substituent include an aromatic ring group and a halogen atom. Among these, since it is thermally stable, an alkyl group is preferable, a C1-C12 alkyl group is more preferable, and a C3-C8 branched alkyl group is still more preferable. In addition, it is preferable that the substituent does not have a benzyl proton because the adduct according to the present invention is thermally stable and hardly decomposes when used as the catalyst for the decarbonylation reaction of the present invention. That is, the substituent is particularly preferably an alkyl group having 3 to 8 carbon atoms having no benzyl proton, and most preferably a t-butyl group.

In addition, when Ar < ¹ > -Ar < ⁴ > is an aromatic ring group which has a substituent, although various isomers exist, Ar < ¹ > -Ar < ⁴ > may be any of them. Examples of these isomers include 2- (or 3-, 4-) methylphenyl group, 2- (or 3-, 4-) ethyl when Ar ^{1 to} Ar ⁴ are a phenyl group having a substituent. 1 carbon number such as phenyl group, 2,3- (or 3,4-) dimethylphenyl group, 2,4,6-trimethylphenyl group, 4-trifluoromethylphenyl group, 3,5-bistrifluoromethylphenyl group An alkylphenyl group in which an alkyl group of -12 or a halogenated alkyl group is bonded to a phenyl group; an alkoxy group having 1-12 carbon atoms such as a 3-methoxyphenyl group or a 2,4,6-trimethoxyphenyl group; Alkoxyphenyl group bonded to the group; 2- (or 3-, 4-) nitrophenyl group; halogen source such as 3- (or 4-) chlorophenyl group, 3-fluorophenyl group There like halophenyl group attached to the phenyl group.

Ar ^{1 to} Ar ⁴ may be bonded to each other or bridged between two groups.
In the tetraarylphosphonium halide according to the present invention, it is preferable that at least any one group of Ar ^{1 to} Ar ⁴ is a group different from at least one of the other three groups. Here, different groups refer to groups different in any one, including those having different substituents, different types, and different substitution positions. In the present invention, the fact that any one group of Ar ¹ to Ar ⁴ is different from at least one of the other three groups is referred to as “asymmetric”. When the tetraarylphosphonium halide according to the present invention is asymmetric, at least any one group of Ar ^{1 to} Ar ⁴ is a group different from at least one of the other three groups, so that the solubility is excellent.

When the tetraarylphosphonium halide according to the present invention is asymmetric, the remaining three groups of Ar ^{1 to} Ar ⁴ may be the same as or different from each other. As the tetraarylphosphonium halide according to the present invention, at least any one of Ar ¹ to Ar ⁴ is an aromatic ring group having a substituent and the remaining group is an unsubstituted aromatic ring group because it is likely to be thermally stable. It is particularly preferable that at least ^one of Ar ^{1 to} Ar ⁴ is an aryl group having a substituent and the remaining group is an unsubstituted aryl group.

The halogen atom X in the general formula (4) is a halogen atom such as a chlorine atom, a bromine atom, or an iodine atom. Among these, a chlorine atom is preferable because it easily acts as a highly active catalyst in the decarbonylation reaction according to the present invention.
Further, the aryl group in the tetraarylphosphonium salt represented by the general formula (4) is preferably a phenyl group which may have a substituent. Further, tetraarylphosphonium chloride having no benzyl proton is more preferable, and tetraarylphosphonium chloride having no benzyl proton is particularly preferable.

Preferable specific examples of the tetraarylphosphonium halide according to the present invention include the following compounds. That is, Ar ^{1 to} Ar ⁴ are all unsubstituted aromatic hydrocarbon groups such as tetraphenylphosphonium chloride, p-biphenyltriphenylphosphonium chloride, 1-naphthyltriphenylphosphonium chloride, 2-naphthyltriphenylphosphonium chloride, and the like. Is mentioned. Examples of the organic phosphonium chloride in which Ar ^{1 to} Ar ⁴ are an unsubstituted aromatic hydrocarbon group or a substituted aromatic hydrocarbon group include 4-t-butylphenyltriphenylphosphonium chloride, m-trifluoromethylphenyltri Compounds having an aromatic hydrocarbon group having an alkyl group and having no benzyl proton such as phenylphosphonium chloride; Compounds having an aromatic hydrocarbon group having a halogen atom such as p-chlorophenyltriphenylphosphonium chloride; m-methoxyphenyl Compounds having an aromatic hydrocarbon group having an alkoxy group such as triphenylphosphonium chloride, p-methoxyphenyltriphenylphosphonium chloride, p-ethoxyphenyltriphenylphosphonium chloride; p-aminophenyl Compounds having an aromatic hydrocarbon group having an amino group, such as triphenylphosphonium chloride; Compounds having an aromatic hydrocarbon group having a cyano group, such as m-cyanophenyltriphenylphosphonium chloride and p-cyanophenyltriphenylphosphonium chloride And a compound having an aromatic hydrocarbon group having a nitro group, such as p-nitrophenyl-tri-p-tolylphosphonium chloride. Among these, the tetraarylphosphonium halide according to the present invention is preferably tetraphenylphosphonium chloride which may have a substituent, and particularly preferably 4-t-butylphenyltriphenylphosphonium chloride.

  Examples of the hydrogen halide according to the present invention include hydrogen fluoride, hydrogen chloride, hydrogen bromide, and hydrogen iodide. When the halogen of the hydrogen halide according to the present invention is used as a catalyst for decarbonylation reaction or the like, if the number of halogens increases, the types of by-products increase and the reaction system tends to become complicated. The same halogen as that of the tetraarylphosphonium halide is preferred. That is, the hydrogen halide according to the present invention is preferably hydrogen chloride, and the adduct body according to the present invention is preferably an adduct body of tetraarylphosphonium chloride and hydrogen chloride, and 4-t-butylphenyltriphenylphosphonium chloride and chloride. An adduct with hydrogen is particularly preferred.

  The adduct body is used as a term meaning an adduct crystal. The adduct body according to the present invention usually includes a solid in which hydrogen halide is added to tetraarylphosphonium halide, a melted or dissolved substance thereof, and the like. In the adduct according to the present invention, 0.01 to 1.0 mole of hydrogen halide is usually added to 1 mole of tetraarylphosphonium halide.

  The adduct body according to the present invention is presumed to be dissolved in the reaction solution for the decarbonylation reaction in the method for producing diphenyl carbonate of the present invention, hydrogen halide is liberated, and the tetraarylphosphonium halide functions as a catalyst. The Therefore, in the method for producing diphenyl carbonate of the present invention, the catalyst may be supplied as tetraarylphosphonium chloride or as an adduct with hydrogen chloride.

  In the method for producing diphenyl carbonate of the present invention, the total amount of tetraarylphosphonium halide and / or adduct in the reactor (hereinafter sometimes simply referred to as “total amount of tetraarylphosphonium halide”) has a reaction rate. A large amount is preferable in terms of easy speed, but a small amount is preferable in that the catalyst is difficult to precipitate during the purification process of diphenyl carbonate. Therefore, specifically, it is preferably 1.0% by weight or more in total, more preferably 2.0% by weight or more, particularly preferably 3.0% by weight or more, It is preferably 15% by weight or less, more preferably 10% by weight or less, and further preferably 8% by weight or less. Further, the total amount of tetraarylphosphonium halide is preferably 0.001 mol or more and more preferably 0.1 mol or more with respect to 100 mol of the total molar amount of diphenyl oxalate and diphenyl carbonate in the reactor. On the other hand, it is preferably 50 mol or less, and more preferably 20 mol or less. The tetraarylphosphonium halide and its adduct may be used singly or in plural ratios and in any combination, and the preferred amount used when plural types are used is the total amount. Represents.

In the method for producing diphenyl carbonate of the present invention, the relative amount of diphenyl oxalate and the total amount of tetraarylphosphonium halide supplied to the reactor is the total amount of diphenyl oxalate and tetraarylphosphonium halide in the reactor. Therefore, the total amount of tetraarylphosphonium halide is preferably 0.1 mol or more, more preferably 1 mol or more, with respect to 100 mol of diphenyl oxalate. , 50 mol or less, preferably 20 mol or less.

[Halogen compounds]
In the method for producing diphenyl carbonate of the present invention, it is preferable to use a halogen compound (hereinafter sometimes referred to as “halogen compound according to the present invention”) together with a catalyst because the decarbonylation reaction is easily maintained with high selectivity. .
Examples of the halogen compound according to the present invention include the following inorganic halogen compounds and / or organic halogen compounds. Of these halogen compounds, chlorine compounds are preferred. The halogen compound has a molar ratio (the total amount of halogen compound / tetraarylphosphonium halide) to the total amount of tetraarylphosphonium halide of usually 0.0001 to 3.00, preferably 0.001 to 1.00. It is good to be used for. In addition, a halogen compound may be used individually by 1 type, or multiple types may be used by arbitrary ratios and combinations, and said preferable usage-amount in the case of using multiple types represents the total amount.

  Examples of inorganic halogen compounds include aluminum halides such as aluminum chloride and aluminum bromide; platinum group metal halides such as platinum chloride, chloroplatinic acid, ruthenium chloride, and palladium chloride; phosphorus trichloride, phosphorus pentachloride, Phosphorus halides such as phosphorus oxychloride, phosphorus tribromide, phosphorus pentabromide and phosphorus oxybromide; hydrogen halides such as hydrogen chloride and hydrogen bromide; thionyl chloride, sulfuryl chloride, sulfur dichloride, dichloride dichloride Sulfur halides such as sulfur; Halogen alone such as chlorine and bromine.

Examples of the organic halogen compound include a compound composed of a carbon atom, a halogen atom such as a chlorine atom or a bromine atom, and at least one atom selected from a hydrogen atom, an oxygen atom, a nitrogen atom, a sulfur atom and a silicon atom. Is mentioned. Examples of such an organic halogen compound include a structure in which a halogen atom is bonded to saturated carbon (C-Hal), a structure in which a halogen atom is bonded to carbonyl carbon (-CO-Hal), and a halogen to a silicon atom. An organic halogen compound having a structure in which atoms are bonded (—C—Si—Hal) or a structure in which a halogen atom is bonded to a sulfur atom (CSO ₂ —Hal) is preferably used. However, H
al represents a halogen atom such as a chlorine atom or a bromine atom. These structures are represented by, for example, general formulas (a), (b), (c), and (d), respectively.

(In the formula, Hal represents a halogen atom such as a chlorine atom or a bromine atom, n ¹ represents an integer of ¹ to 4, and n ² represents an integer of 1 to ^3. )
Specific examples of the organic halogen compound include the following compounds.
Examples of the organic halogen compound having a structure in which a halogen atom is bonded to saturated carbon as represented by the general formula (a) include chloroform, carbon tetrachloride, 1,2-dichloroethane, butyl chloride, and dodecyl chloride. Alkyl halides, aralkyl halides such as benzyl chloride, benzotrichloride, triphenylmethyl chloride, α-bromo-o-xylene, and halogen-substituted aliphatics such as β-chloropropionitrile and γ-chlorobutyronitrile Examples include nitriles and halogen-substituted aliphatic carboxylic acids such as chloroacetic acid, bromoacetic acid, and chloropropionic acid.

  Examples of the organic halogen compound having a structure in which a halogen atom is bonded to the carbonyl carbon as represented by the general formula (b) include acetyl chloride, oxalyl chloride, propionyl chloride, stearoyl chloride, benzoyl chloride, and 2-naphthalenecarboxylic acid. Examples thereof include acid halides such as acid chloride and 2-thionephencarboxylic acid chloride, aryl halogenoglyoxylates such as phenyl chloroglyoxylate, and aryl halides such as phenyl chloroformate.

Examples of the organic halogen compound having at least one structure in which a halogen atom is bonded to a silicon atom as represented by the general formula (c) include halogenated silanes such as diphenyldichlorosilane and triphenylchlorosilane. .
Examples of the organic halogen compound having a structure in which a halogen atom is bonded to a sulfur atom as represented by the general formula (d) include sulfonyl halides such as p-toluenesulfonic acid chloride and 2-naphthalenesulfonic acid chloride. Is mentioned.

  Of these, inorganic halogen compounds are preferred, hydrogen halides are more preferred, and hydrogen chloride is particularly preferred because production of byproducts derived from halogen compounds is easily suppressed. In addition, when the number of halogen atoms present in the reaction system increases, the number of by-products increases and the reaction system tends to become complicated. Therefore, the halogen of the halogen compound according to the present invention is a tetraarylphosphonium halide used as a catalyst. And / or the same halogen as that contained in the adduct body. That is, in the production of diphenyl carbonate of the present invention, it is particularly preferable to use tetraarylphosphonium chloride and / or its hydrogen chloride adduct as a catalyst, and further to use hydrogen chloride as the halogen compound according to the present invention.

[Decarbonylation reaction]
The decarbonylation reaction in the method for producing diphenyl carbonate of the present invention (hereinafter sometimes referred to as “decarbonylation reaction according to the present invention” or simply “decarbonylation reaction”) is preferably carried out by a liquid phase reaction. The reaction temperature of the decarbonylation reaction is preferably high in terms of reaction rate, but is preferably low in terms of the purity of diphenyl carbonate. Accordingly, the reaction temperature is preferably 100 ° C. or higher, particularly 160 ° C. or higher, particularly 180 ° C. or higher, and usually 450 ° C. or lower, particularly 400 ° C. or lower, especially 350 ° C. or lower. The pressure during the reaction may be determined from the process requirements.

The decarbonylation reaction may be a batch reaction or a continuous reaction, but industrially a continuous reaction is preferred. As a general method for the continuous reaction, the methods described in JP-A-10-109962, JP-A-10-109963, JP-A-2006-89416 and the like can be used.
The decarbonylation reaction does not require the use of a solvent when the reaction is carried out at a temperature equal to or higher than the melting point of the substance used for the reaction, but an aprotic polar solvent such as sulfolane, N-methylpyrrolidone, dimethylimidazolidone, or a hydrocarbon solvent. Aromatic hydrocarbon solvents and the like can also be used as appropriate.

  The material and type of the reactor are not particularly limited as long as diphenyl carbonate can be generated by decarbonylation reaction of diphenyl oxalate, but an aromatic monohydroxy compound such as phenol may be generated in a side reaction. A metal container made of a conductive material or a glass-lined container is preferred. As such a reactor, for example, a single tank or multi-tank type fully mixed reactor (stirring tank), a tower reactor, or the like can be used.

[Purification of diphenyl carbonate]
By the decarbonylation reaction, diphenyl carbonate corresponding to the raw material diphenyl oxalate can be generated. The reaction solution after the decarbonylation reaction contains diphenyl carbonate, a decarbonylation catalyst, and unreacted diphenyl oxalate. In addition, there may be contained by-products generated by rearrangement, decomposition, reaction, etc. of diphenyl oxalate, diphenyl carbonate, decarbonylation catalyst, and the like. Examples of by-products include phenol and phenyl p-chlorobenzoic acid. Moreover, when the above-mentioned halogen compound is used, this halogen compound or its by-product may be contained. Therefore, the diphenyl carbonate obtained by the carbonyl reaction is appropriately purified in order to obtain a purity and form corresponding to the application.

Carbon monoxide by-produced in the decarbonylation reaction is preferably gas-liquid separated from the reaction solution and discharged. Carbon monoxide can also be reused as a raw material for producing diphenyl oxalate from nitrite and carbon monoxide. (For example, see the method described in JP-A-10-152457, etc.). Here, when impurities such as phenol, carbon dioxide and hydrogen halide are contained in carbon monoxide, it is preferably used as a raw material for diphenyl oxalate after passing through a purification apparatus such as an absorption tower or a scrubber.

[Catalyst recovery method]
In the catalyst recovery method of the present invention, the catalyst used in the decarbonylation reaction is recovered from the remaining liquid obtained from the component containing diphenyl carbonate from the reaction liquid after the decarbonylation reaction (catalyst recovery step). Here, the catalyst recovery method of the present invention includes a step of bringing the residual liquid into contact with a polar organic solvent and hydrogen chloride. Moreover, the polar organic solvent used for catalyst recovery is recovered and reused in the catalyst recovery step. And the manufacturing method of diphenyl carbonate of this invention performs the said decarbonylation reaction using this collect | recovered deposit as a catalyst.

The method for producing diphenyl carbonate of the present invention is particularly preferably a method having the following first to fourth steps in this order, and more preferably having the following first to fourth steps in this order.
1st process: The process which produces | generates a diphenyl carbonate by carrying out the decarbonylation reaction of diphenyl oxalate in presence of the tetraaryl phosphonium halide and / or the adduct body of the tetraaryl phosphonium halide and hydrogen halide,
2nd process: The process of isolate | separating the component containing diphenyl carbonate from the reaction liquid obtained at the 1st process,
Third step: A step of precipitating the catalyst contained in the residual liquid from which the component containing diphenyl carbonate has been separated in the second step (here, the third step includes adding a polar organic solvent and hydrogen chloride to at least a part of the residual liquid. Having a step of contacting),
Fourth step: A step of supplying at least part of the precipitate obtained in the third step to the first step as a catalyst for the decarbonylation reaction.

The first step is preferably performed as in the decarbonylation reaction according to the present invention described above.
In the second step, the component containing diphenyl carbonate is separated from the reaction solution obtained in the first step. Separation in the second step can be performed by a known method such as distillation, extraction, or crystallization. The tetraarylphosphonium halide according to the present invention and the adduct according to the present invention usually have a high boiling point. Therefore, the separation in the second step is preferably a method in which diphenyl carbonate is separated by distillation. That is, in the method for producing diphenyl carbonate of the present invention, the tetraarylphosphonium halide according to the present invention and / or the adduct according to the present invention is obtained by evaporating and removing diphenyl carbonate contained in the reaction solution after the decarbonylation reaction. It is preferable to obtain a residual liquid containing. In addition, when a high boiling point substance such as diphenyl oxalate or a fleece rearrangement compound of diphenyl carbonate is contained in the reaction solution after the decarbonylation reaction, these are usually contained in the catalyst solution.

  Distillation of diphenyl carbonate may be carried out in the reactor where the decarbonylation reaction has been carried out, or the reaction solution may be transferred to an evaporator. The evaporation apparatus (evaporation method) is not particularly limited as long as the above object can be achieved. As the evaporation apparatus, for example, it is preferable to use a falling film evaporator, a thin film evaporator or the like because separation is easy in a short time. Moreover, when evaporating in the reactor, it is preferable to evaporate while gradually reducing pressure while stirring so that bumping hardly occurs. The time required for the separation is also affected by the heat transfer efficiency and the shape of the separation container, but it is preferably performed in a short time from the point that impurities are not easily produced, preferably 20 hours or less, more preferably 15 hours or less, 10 hours or less is particularly preferable. Evaporation is preferably performed at a low temperature and a low pressure from the viewpoint that impurities are not easily produced as a by-product. The pressure is preferably evaporated under reduced pressure, and the temperature is preferably lower than the reaction temperature in the decarbonylation reaction. Specifically, the pressure is preferably 0.1 kPaA or more, more preferably 0.2 kPaA or more, while 50 kPaA or less is preferable, and 20 kPaA or less is more preferable. The temperature is preferably 100 ° C. or higher, particularly 160 ° C. or higher, particularly 180 ° C. or higher, and usually 450 ° C. or lower, particularly 400 ° C. or lower, especially 350 ° C. or lower.

  When distillation is performed under the above preferred conditions, diphenyl carbonate is usually contained in the evaporated fraction in an amount of 70% by weight or more, preferably 80% by weight or more, and more preferably 90% by weight or more. The upper limit is usually 100% by weight. When diphenyl oxalate is contained in this fraction, it is usually 0.001% by weight or more, preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and on the other hand, usually 2% by weight Hereinafter, it is preferably 1% by weight or less, more preferably 0.5% by weight or less. Components other than these may include phenol and the like, but the content in that case is usually 1% by weight or less, preferably 0.5% by weight or less, more preferably 0.3% by weight or less. .

The evaporated diphenyl carbonate may be used as it is for the production of polycarbonate or the like, but may be further purified according to the required purity. Further purification can be performed by distillation or adsorption. Specifically, it is preferable to carry out distillation purification using an evaporation apparatus such as a plate column or packed column having 5 to 50 theoretical plates.
In a 3rd process, the catalyst contained in the residual liquid which isolate | separated the component containing diphenyl carbonate in the 2nd process is deposited. Here, the third step has a step of bringing a polar organic solvent and hydrogen chloride into contact with at least a part of the residual liquid. It is estimated that the catalyst is precipitated by the following phenomenon.

  When the tetraarylphosphonium halide is used as a catalyst in the decarbonylation reaction, the residual liquid from which the component containing diphenyl carbonate is separated in the second step contains the tetraarylphosphonium halide. Further, when an adduct of tetraarylphosphonium halide and hydrogen halide is used as a catalyst for the decarbonylation reaction, it is considered that tetraarylphosphonium halide in which hydrogen halide is liberated from the adduct is included.

Here, when the tetraarylphosphonium halide according to the present invention has high solubility in a polar organic solvent, even if the residual liquid is brought into contact with the polar organic solvent, it is only diluted with the polar organic solvent. When it comes into contact with hydrogen chloride, it becomes an adduct with hydrogen chloride and precipitates.
Further, when the tetraarylphosphonium halide according to the present invention has low solubility in a polar organic solvent, when the residual liquid is brought into contact with the polar organic solvent, diphenyl carbonate or impurities remaining in the residual liquid are usually polar organic solvents. However, since the tetraarylphosphonium halide precipitates, the residual liquid becomes a slurry. Here, when the tetraarylphosphonium halide contained in the residual liquid is brought into contact with hydrogen chloride, it becomes an adduct with hydrogen chloride and dissolves because the solubility in a polar organic solvent increases. However, an adduct of tetraarylphosphonium halide can be precipitated by bringing water into contact therewith.

  The residual liquid may be contacted with the polar organic solvent and hydrogen chloride at the same time, or one of them may be contacted first and then the other, but in terms of easy recovery of a high-purity catalyst. It is preferable to make contact with hydrogen chloride after contact with a polar organic solvent, such as by using a polar organic solvent that has absorbed hydrogen chloride, or contact with hydrogen chloride after contact with a polar organic solvent. More preferably, it is made. This is because when hydrogen chloride comes into contact with the residual liquid first, phenol is generated by decomposition of diphenyl carbonate contained in the residual liquid, and there is a possibility that the reaction of tetraarylphosphonium halide to tetraarylphosphonium phenolate occurs. This is because it is considered that this reaction is unlikely to occur simultaneously with the polar organic solvent or when the polar organic solvent is contacted first.

  The polar organic solvent to be brought into contact with the residual liquid is highly compatible with a small amount of diphenyl carbonate and by-product high-boiling substances and water contained in the residual liquid, and easily dissolves the adduct of tetraarylphosphonium halide and hydrogen halide. A solvent that easily precipitates tetraarylphosphonium halide is preferred. Preferable examples of the polar organic solvent include ketones, ethers, halogenated carbons, and esters.

  Examples of ketones include dimethyl ketone, diethyl ketone, methyl ethyl ketone, methyl n-propyl ketone, methyl isopropyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, methyl n-pentyl ketone, methyl isopentyl ketone, and ethyl n-propyl ketone. Lower alkyl ketones having 1 to 15 carbon atoms such as ethyl isopropyl ketone, ethyl n-butyl ketone and ethyl isobutyl ketone, and cyclic ketones having 3 to 10 carbon atoms such as cyclohexanone and cyclopentanone.

  Examples of ethers include dimethyl ether, diethyl ether, methyl ethyl ether, methyl n-propyl ether, methyl isopropyl ether, methyl n-butyl ether, methyl isobutyl ether, methyl n-pentyl ether, methyl isopentyl ether, ethyl n-propyl. C2-C10 lower alkyl ethers such as ether, ethyl isopropyl ether, ethyl n-butyl ether, ethyl isobutyl ether, dimethoxyethane, diethoxyethane; cyclic ethers such as tetrahydrofuran and diaryl ethers such as diphenyl ether It is done.

  Examples of the halogenated hydrocarbons include monochloromethane, dichloromethane, trichloromethane, 1-chloroethane, 1,2-dichloroethane, 1,1-dichloroethane, 1,1,2-trichloroethane, 1-chloropropane, 2-chloropropane, Examples thereof include halogenated hydrocarbons having 1 to 6 carbon atoms such as 1,2-dichloropropane, 1,1-dichloropropane and 2,2-dichloropropane.

Examples of the esters include alkyl aliphatic carboxylic acid esters, alkyl carbonic acid diesters, alkyl oxalic acid diesters, and fatty acid esters of ethylene glycol. Examples of the alkyl aliphatic carboxylic acid esters include methyl formate, ethyl formate, n-propyl formate, isopropyl formate, n-butyl formate, and isobutyl formate; lower alkyl formate; methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate , Lower alkyl acetates such as n-butyl acetate and isobutyl acetate and lower alkyl propionates such as methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, n-butyl propionate, isobutyl propionate, etc. And lower alkyl aliphatic carboxylic acid esters. Examples of the alkyl carbonate diester include lower alkyl carbonate diesters such as dimethyl carbonate, diethyl carbonate, butyl carbonate, and methyl ethyl carbonate. Examples of the alkyl oxalic acid diester include lower alkyl oxalic acid diesters such as dimethyl oxalate and diethyl oxalate. Ethylene glycol acetate includes ethyl acetate, propyl acetate, butyl acetate and the like. Examples of ethylene glycol fatty acid esters include ethylene glycol acetate.

  Among these, polar organic solvents having 3 to 15 carbon atoms in the polar organic solvent are preferable, and polar organic solvents having 3 to 10 are more preferable. Further, a polar organic solvent having an asymmetric structure such as methyl isopropyl ketone and methyl isobutyl ketone is preferable. And ketones are preferable and alkyl ketones are more preferable. Therefore, alkyl ketones are particularly preferable, alkyl ketones having 3 to 10 carbon atoms are more preferable, and alkyl ketones having an asymmetric structure such as methyl isopropyl ketone and methyl isobutyl ketone are most preferable.

  The amount (weight) of the polar organic solvent to be brought into contact with the residual liquid is preferably large in that precipitation of diphenyl carbonate and by-product high-boiling substances and solidification of the residual liquid are difficult to occur. And it is preferable that the energy required for the separation and recovery of the polar organic solvent is small. Therefore, specifically, it is preferably 0.5 times or more with respect to the remaining liquid, more preferably 1 time or more, and on the other hand, it is preferably 10 times or less, and preferably 5 times or less. It is more preferable that it is 3 times or less. If the amount of water in the polar organic solvent is too large, the phenol produced as a by-product by reacting with diphenyl carbonate contained in the residual liquid reacts with tetraarylphosphonium halide to form tetraarylphosphonium phenoxide. Is 2.0% by weight or less, preferably 1.0% by weight or less, and more preferably 0.5% by weight or less.

  Hydrogen chloride to be brought into contact with the remaining liquid may contain hydrogen chloride, and may be supplied as hydrogen chloride gas or hydrochloric acid. Since hydrogen chloride is used to convert the tetraarylphosphonium halide contained in the residual liquid into a hydrogen chloride adduct of tetraarylphosphonium halide, the amount of hydrogen chloride brought into contact with the residual liquid is the amount of tetraaryl contained in the residual liquid. It is preferably 1 mol or more, more preferably 1.1 mol or more, and on the other hand, it is preferably 5 mol or less, and preferably 2 mol or less with respect to 1 mol of phosphonium halide. Further preferred.

When the residual liquid is brought into contact with a polar organic solvent and then brought into contact with hydrogen chloride, it is difficult to solidify the residual liquid. Therefore, it is preferable to contact with hydrogen chloride at a temperature not lower than the melting point of diphenyl carbonate and not higher than the boiling point of the polar organic solvent. In terms of the catalyst recovery efficiency, the temperature of the hydrogen chloride to be contacted and the temperature of the polar organic solvent containing hydrogen chloride in contact with the polar organic solvent containing hydrogen chloride are preferably low. Is preferably 50 ° C. or lower, more preferably 40 ° C. or lower, and particularly preferably 30 ° C. or lower. This is because diphenyl carbonate and by-product high-boiling substances may be hydrolyzed by water or the like contained in a polar organic solvent to produce phenol when in contact with hydrogen chloride.
The amount of water to be contacted in the third step is preferably large in that the hydrogen chloride adduct of tetraarylphosphonium halide is precipitated and the recovery rate tends to be high. It is preferable that the raw high-boiling substance is less likely to be precipitated and the amount of the high-purity catalyst is easy to recover. Therefore, specifically, the amount of water (weight ratio) with respect to the amount of the polar organic solvent is preferably 0.001 times or more, more preferably 0.01 times or more, and more preferably 0.02 times or more. On the other hand, it is preferably 0.5 times or less, more preferably 0.2 times or less, and particularly preferably 0.1 times or less. The temperature of the water to be contacted is preferably 50 ° C. or lower, more preferably 40 ° C. or lower, and particularly preferably 30 ° C. or lower. The contact with water is preferably performed slowly over time in that the recovered catalyst tends to be highly pure.
That is, it is preferable to divide water or make small amounts contact rather than contacting the whole amount of water at once.

In the fourth step, at least a part of the precipitate obtained in the third step is supplied to the first step as a catalyst for the decarbonylation reaction. The slurry obtained in the third step can be reused as a catalyst by drying the solid obtained by solid-liquid separation and supplying it to a reactor for decarbonylation reaction. However, from the viewpoint of preventing the accumulation of high-boiling substances, the slurry obtained in the third step is preferably supplied to the first step after removing components having a higher boiling point than diphenyl carbonate. Examples of the components removed here include by-product high-boiling substances such as phenyl p-hydroxybenzoate and phenyl (o-phenoxycarbonylphenyl) carbonate (PCPC). Solid-liquid separation can be performed by pressure filtration or the like. Moreover, a drying can remove a polar organic solvent and water by drying the obtained solid at about 80-220 degreeC and 0.1-50 kPa for about 1 to 10 hours.

In this way, the catalyst recovery method of the present invention uses a tetraarylphosphonium halide and / or an adduct of a tetraarylphosphonium halide and a hydrogen halide as a catalyst for the production of diphenyl carbonate by decarbonylation of diphenyl oxalate. In such a case, a highly pure catalyst can be efficiently recovered from the reaction solution by a simple method.
Further, by continuously performing the first to fourth steps in this order, high-purity diphenyl carbonate can be efficiently and stably continuously produced. However, even if the catalyst recovery process is performed from the total amount of the residual liquid obtained in the second process in the third process, a part of the catalyst is also removed along with the process such as the removal of the by-product high-boiling substances. It may be done. Therefore, when a continuous reaction is performed, together with the recovered catalyst, the tetraarylphosphonium halide and / or the tetraarylphosphonium halide and the hydrogen halide are used together with the recovered catalyst so that the total amount of the tetraarylphosphonium halide is within the above-described preferable range. This can be done by supplying an adduct body.

[Recovery of polar organic solvent]
The catalyst recovery method of the present invention includes a step of recovering the polar organic solvent used in the catalyst recovery described above and reusing it in the catalyst recovery step. Here, since the polar organic solvent used for catalyst recovery contains hydrogen chloride used for catalyst recovery, it is reused after purification by performing the following steps (A) and (B) in this order. It is preferable to do.
(A) Step: The polar organic solvent used for the catalyst recovery is evaporated and distilled into a liquid-liquid separator containing water, and the polar organic solvent phase of the liquid-liquid separator is moved to the residual liquid side. Removing at least part of the hydrogen chloride contained in the residual liquid by returning,
(B) Process: The process of distilling the liquid obtained at the (A) process.

  In step (A), the residual liquid from which the catalyst has been recovered as a precipitate as described above is evaporated and distilled into a liquid-liquid separator. Here, since water is put in the liquid-liquid separator, it is divided into a polar organic solvent phase (upper phase) and a water phase (lower phase) in the liquid-liquid separator. Hydrogen chloride is more easily dissolved in the water phase than in the polar organic solvent phase. Therefore, the hydrogen chloride contained in the polar organic solvent can be removed by returning the phase of the polar organic solvent to the residual liquid side.

The distillation apparatus (evaporation method) used in the step (A) is not particularly limited as long as the above object can be achieved. As the evaporator, for example, a falling film evaporator, a thin film evaporator and the like are preferable because they can be easily separated in a short time. Moreover, when evaporating in the reactor, it is preferable to evaporate while gradually reducing pressure while stirring so that bumping hardly occurs. The time required to remove hydrogen chloride contained in the polar organic solvent is also affected by heat transfer efficiency and the shape of the separation vessel, but it is preferable to carry out in a short time from the point that impurities by-product hardly occurs, 2
0 hours or less is preferable, 15 hours or less is more preferable, and 10 hours or less is particularly preferable. Evaporation is preferably carried out at a low temperature and a low pressure from the viewpoint that impurities are not easily produced as a by-product. The pressure is preferably evaporated under normal pressure or reduced pressure, and the temperature is preferably a temperature at which hydrogen chloride is distilled off. Specifically, the pressure is preferably 1 kPaA or more, and more preferably 2 kPaA or more. On the other hand, 100 kPaA or less is preferable, and 80 kPaA or less is more preferable. The temperature is usually 50 ° C. or higher, preferably 60 ° C. or higher, particularly preferably 70 ° C. or higher. On the other hand, it is usually 200 ° C. or lower, preferably 190 ° C. or lower, particularly preferably 180 ° C. or lower.

  The amount and temperature of water to be added to the liquid-liquid separator are not particularly limited as long as the distilled polar organic solvent and hydrogen chloride are liquid-liquid separated. The amount of water is preferably 1% by weight or more, more preferably 2% by weight or more of the residual liquid recovered as a precipitate of the catalyst, while it is preferably 50% by weight or less, More preferably, it is 30 wt% or less. The temperature of the liquid-liquid separator is preferably 60 ° C. or lower because it is easy to perform liquid-liquid separation, and more preferably 50 ° C. or lower. On the other hand, since the aqueous phase is difficult to solidify, The temperature is preferably 0 ° C or higher, more preferably 5 ° C or higher.

  When the step (A) is performed under such preferable conditions, the polar organic solvent is usually 70% by weight or more, preferably 80% by weight or more, more preferably 90% in the phase of the polar organic solvent returned to the residual liquid side. Containing more than% by weight. The upper limit is usually 100% by weight. Further, hydrogen chloride contained in the phase of the polar organic solvent returned to the residual liquid side is usually 1% by weight or less, preferably 0.5% by weight or less, and more preferably 0.3% by weight or less.

  In step (B), the liquid obtained in step (A) is distilled. Distillation can remove water from the polar organic solvent. The distillation apparatus (evaporation method) used in the step (A) can be carried out in the same manner as in the step (A). The distillation conditions are not particularly limited as long as the polar organic solvent and water can be separated. However, the distillation temperature is preferably high in terms of easy separation of the polar organic solvent and water, but in terms of difficulty in mixing high-boiling compounds such as phenol by-produced by the decarbonylation reaction into the polar organic solvent. It is preferable that the temperature is low.

  In this way, the catalyst recovery method of the present invention efficiently recovers and reuses a high-purity catalyst by a simple method, and efficiently recovers the polar organic solvent used for catalyst recovery. New polar organic solvents can be reused. By reusing the catalyst recovered by the catalyst recovery method of the present invention, it is possible to efficiently produce high-purity diphenyl carbonate stably.

[Diphenyl carbonate]
In the method for producing diphenyl carbonate according to the present invention, since the high-purity catalyst recovered as described above is reused, the high-purity catalyst is used in spite of the decarbonylation reaction using the reused catalyst. Diphenyl carbonate can be produced stably and continuously. Therefore, the purity of diphenyl carbonate obtained by the above-described method for producing diphenyl carbonate of the present invention is usually 99.0.
% By weight or more, preferably 99.3% by weight or more, more preferably 99.5% by weight or more. When impurities are included, ionic chlorine or the like may be included. In this case, the content is usually 1 ppm by weight or less, preferably 0.1 ppm by weight or less, more preferably 0.01 ppm by weight. It is as follows.

[Production method of polycarbonate]
Polycarbonate, which is one of the uses of diphenyl carbonate produced in the present invention, comprises diphenyl carbonate produced by the above method and a dihydroxy compound typified by bisphenol A, an alkali metal compound and / or an alkaline earth metal compound. Can be produced by transesterification in the presence of. The dihydroxy compound to be transesterified with diphenyl carbonate may be an aromatic dihydroxy compound or an aliphatic dihydroxy compound, but an aromatic dihydroxy compound is preferred. The transesterification reaction can be carried out by appropriately selecting a known method. An example using diphenyl carbonate and bisphenol A as raw materials will be described below.

  In the above polycarbonate production method, diphenyl carbonate is preferably used in excess relative to bisphenol A. The amount of diphenyl carbonate used with respect to bisphenol A is preferably large in that the produced polycarbonate has few terminal hydroxyl groups and is excellent in the thermal stability of the polymer, and the transesterification reaction rate is high, and the polycarbonate having a desired molecular weight. It is preferable that the amount is small in that it is easy to manufacture. Specifically, for example, it is preferably used in an amount of usually 1.001 mol or more, preferably 1.02 mol or more, usually 1.3 mol or less, preferably 1.2 mol or less with respect to 1 mol of bisphenol A.

As a raw material supply method, bisphenol A and diphenyl carbonate can be supplied in solid form, but it is preferable to supply one or both in a liquid state by melting them.
When producing a polycarbonate by transesterification of diphenyl carbonate and bisphenol A, a catalyst is usually used. In the above polycarbonate production method, it is preferable to use an alkali metal compound and / or an alkaline earth metal compound as the transesterification catalyst. These may be used alone, or two or more may be used in any combination and ratio. Practically, an alkali metal compound is desirable.

The catalyst is usually 0.05 μmol or more, preferably 0.08 μmol or more, more preferably 0.10 μmol or more, and usually 5 μmol or less, preferably 4 μmol, relative to 1 mol of bisphenol A or diphenyl carbonate. It is used in a range of not more than mol, more preferably not more than 2 μmol.
When the amount of the catalyst used is within the above range, it is easy to obtain the polymerization activity necessary for producing a polycarbonate having a desired molecular weight, and the polymer color is excellent, and excessive polymer branching does not progress. It is easy to obtain polycarbonate with excellent fluidity.

As the alkali metal compound, a cesium compound is preferable. Preferred cesium compounds are cesium carbonate, cesium bicarbonate, and cesium hydroxide.
In order to produce polycarbonate by the above method, it is preferable to continuously supply both the raw materials to the raw material mixing tank, and to continuously supply the obtained mixture and the transesterification catalyst to the polymerization tank.
In the production of polycarbonate by the transesterification method, both raw materials supplied to the raw material mixing tank are usually stirred uniformly and then supplied to a polymerization tank to which a catalyst is added to produce a polymer.

[Polycarbonate]
As described above, since diphenyl carbonate obtained by the production method of the present invention has a high purity, diphenyl carbonate obtained by the production method of the present invention and a dihydroxy compound are polycondensed in the presence of a transesterification catalyst. A highly pure polycarbonate can be obtained.
In particular, high purity diphenyl carbonate can be efficiently obtained by the method for producing diphenyl carbonate of the present invention, and therefore, high quality polycarbonate can be obtained using this.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited by a following example, unless the summary is exceeded.

[material]
Diphenyl oxalate used was a product obtained by purifying a primary reagent of Tokyo Chemical Industry Co., Ltd. by simple distillation.
Methyl isobutyl ketone was a product of Wako Pure Chemical Industries, Ltd. The hydrogen chloride gas used was a product of Sumitomo Seika Co., Ltd. In addition, it was 500 weight ppm when the water concentration in methyl isobutyl ketone was analyzed from the moisture meter ("MKS-500" by Kyoto Electronics Industry Co., Ltd.).

[analysis]
Methyl isobutyl ketone was quantified by gas chromatography under the following procedure and conditions. As a device, “GC-2014” manufactured by Shimadzu Corporation was used. As the column, “DB-17” (inner diameter 0.53 mm, column length 60 m, film thickness 1 μm) manufactured by Agilent Technologies was used. The carrier gas was helium, the flow rate was 7.34 cm ^{3 /} min, and the linear velocity was 50.7 cm / sec. The inlet temperature was 220 ° C and the detector temperature was 260 ° C. The temperature rising pattern of the column was first held at 75 ° C. for 3 minutes, then heated to 10 ° C./minute to 220 ° C., held at 220 ° C. for 10 minutes, and then heated to 40 ° C./minute to 250 ° C. And held for 10 minutes for analysis.

The quantitative determination of hydrogen chloride was performed using a potentiometric titrator (“AT-610” manufactured by Kyoto Electronics Industry Co., Ltd.) using silver nitrate.
The water was quantified using a moisture meter (“MKS-500” manufactured by Kyoto Electronics Industry Co., Ltd.).
The determination of 4-t-butylphenyltriphenylphosphonium chloride and the composition of the recovered catalyst were performed by high performance liquid chromatography under the following procedure and conditions. Apparatus: LC-2010A manufactured by Shimadzu Corporation, Imtakt Cadenza 3 mm CD-C18 250 mm × 4.6 mm ID. Low pressure gradient method. Analysis temperature 30 ° C. Eluent composition: A solution Acetonitrile: water = 7.2: 1.0 wt% / wt%, B solution 0.5 wt% sodium dihydrogen phosphate aqueous solution. Analysis time 0-12 minutes. Liquid A: Liquid B = 65: 35 (volume ratio, the same applies hereinafter). The analysis time is 12 to 35 minutes, the eluent composition is gradually changed to A liquid: B liquid = 92: 8, and the analysis time of 35 to 40 minutes is maintained at A liquid: B liquid = 92: 8, flow rate 1 ml / min. ).

[Synthesis Example 1]
A hydrogen chloride salt of 4-t-butylphenyltriphenylphosphonium chloride was synthesized by the following method.
First, 4-t-butylphenyltriphenylphosphonium bromide was synthesized by the method described in JP2013-82695A. This bromide body was converted into 4-t-butylphenyltriphenylphosphonium chloride (chloride body) by the method described in JP-A-11-217393.

The separable flask was charged with this 4-t-butylphenyltriphenylphosphonium chloride, butanol and hydrochloric acid, and heated to 90 ° C. in a nitrogen atmosphere to obtain a uniform solution.
Thereafter, the separable flask was cooled to room temperature to obtain a slurry. The solid obtained by filtering this slurry through a glass filter was transferred to an eggplant type flask. The eggplant-shaped flask was attached to a rotary evaporator equipped with an oil bath, and the oil bath was heated to 100 ° C. and dried at a pressure of 10 Torr for 2 hours to obtain a solid. As a result of analyzing this solid with a potentiometric titrator “AT-610” manufactured by Kyoto Electronics Industry Co., Ltd., it was found to be 14.2% by weight, so that it is a hydrogen chloride salt of 4-t-butylphenyltriphenylphosphonium chloride. Was confirmed. Moreover, the moisture content measured using the moisture meter (Kyoto Electronics Industry Co., Ltd. "MKS-500") was 0.4 weight%.

[Example 1]
In a 2000 cm ³ eggplant-shaped flask equipped with a stir bar, 271 g (1.1 mol) of diphenyl oxalate and 160 g of hydrogen chloride of 4-t-butylphenyltriphenylphosphonium chloride (molecular weight 467) synthesized in Synthesis Example 1 were added. And immersed in an oil bath at 240 ° C. The temperature of the oil bath was raised to 240 ° C. and reacted for 2 hours.

After the reaction, a distillation tube was attached to the eggplant type flask, and 20 g of a mixture of diphenyl carbonate and phenol was distilled off under a full vacuum with a diaphragm pump. The obtained residue was cooled to 100 ° C., and then 800 g of methyl isobutyl ketone was added to form a white slurry. This slurry was cooled to room temperature (about 20 ° C.), hydrogen chloride gas (molecular weight 36) 0.01 m ³ (1.2 mol of hydrogen chloride relative to 1 mol of 4-t-butylphenyltriphenylphosphonium chloride contained in the reaction solution). Mole) was absorbed by bubbling, and a visually uniform liquid was obtained. When 40 g of water was added to this solution over 30 minutes, a white slurry was formed again. The slurry obtained by filtering this slurry under reduced pressure was washed with 100 g of methyl isobutyl ketone and then filtered under reduced pressure to obtain 1100 g of a filtrate and 167 g of a solid.

Here, the concentration of methyl isobutyl ketone contained in the obtained filtrate was quantified by gas chromatography, whereby it was 74.0% by weight. In addition, the concentration of water contained in the filtrate was measured with a moisture meter and found to be 3.5% by weight. The concentration of hydrogen chloride contained in the filtrate was quantified with a potentiometric titrator, and found to be 0.3% by weight.
Moreover, the filterability in the vacuum filtration of the obtained solid was favorable. Moreover, when the composition of this solid was analyzed by high performance liquid chromatography, the concentration of 4-t-butylphenyltriphenylphosphonium chloride (molecular weight 431) was 73% by weight. Therefore, the recovery rate of 4-t-butylphenyltriphenylphosphonium chloride recovered as a solid was calculated as (167 g × 0.73 ÷ 431) ÷ (160 g ÷ 467) × 100 = 83%.

  A batch distillation column consisting of a full-jacketed separable flask, a 32 mm column equipped with a thermometer and a stirrer, Shibata Kagaku Co., Ltd.'s “Alder Show” (tray column) and a liquid-liquid separation tank is placed inside the separable flask. When the filtrate was evaporated, the evaporated liquid was supplied to the lower part of the liquid-liquid separation tank through the plate tower, and overflowed from the upper part of the liquid-liquid separation tank to return to the plate tower. In addition, a line connecting the tray tower and the liquid-liquid separation tank was installed so that it could be switched to the initial distillation tank or the mainstream tank instead of the liquid-liquid separation tank.

300 g of the above filtrate was charged into a separable flask. The charged water 20 cm ³ of methyl isobutyl ketone 80 cm ³ (64 g) in liquid-liquid separation tank, the liquid-liquid separation tank was 15 ° C.. Distillation was performed by reducing the pressure in the plate column from normal pressure to 133 kPa and raising the bottom temperature of the separable flask from room temperature to 60.4 ° C. The evaporated liquid distilled into the liquid-liquid separation tank was separated into two phases into a lower phase mainly composed of water and an upper phase mainly composed of methyl isobutyl ketone. Here, the lower phase stayed in the liquid-liquid separation tank, but the upper phase overflowed and returned to the tray column. As water is evaporated together with methyl isobutyl ketone, the interface between the lower phase and the upper phase gradually rises and the top temperature of the plate tower rises, but the ratio of methyl isobutyl ketone and water that evaporates eventually becomes 15 As the saturation solubility of water in isobutyl ketone at 0 ° C. was reached, the temperature rise of the top temperature of the plate column became dull at around 57.7 ° C. and the rise of the interface between the lower phase and the upper phase also stopped.

The line connecting the column tower and the liquid-liquid separation tank is switched from the liquid-liquid separation tank to the first distillation tank, and as the concentration of water contained in the evaporating component decreases, the top temperature of the plate tower increases to 58.2 ° C. Distillation was continued until the temperature rise in the vicinity was slow, and 57 g of the first fraction was obtained. Here, as a result of analyzing the concentration of methyl isobutyl ketone contained in the first fraction by gas chromatography, it was 98.0% by weight.

  With the reflux ratio set to 2, the line connecting the tray tower and the first distillation tank is switched to the main distillation tank, the bottom temperature of the separable flask is raised, and the distillation is continued until it reaches 67.3 ° C. Obtained. The concentration of methyl isobutyl ketone contained in the main distillate was analyzed by gas chromatography and found to be 99.9% by weight. Moreover, the water contained in the main fraction was 0.1% by weight by the moisture meter, and the hydrogen chloride contained in the main fraction was below the detection limit by the potentiometric titrator. Therefore, the recovery rate of methyl isobutyl ketone in the main distillate was calculated as (153 g × 0.999) ÷ (300 g × 0.740 + 64 g) × 100 = 53%. In addition, the recovery rate of methyl isobutyl ketone in the total distillate obtained by adding the recovery amount of methyl isobutyl ketone in the initial distillation is (57 g × 0.980 + 153 g × 0.999) ÷ (300 g × 0.740 + 64 g) × It was calculated that 100 = 92%.

[Example 2]
In Example 1, in addition to 300 g of filtrate in a separable flask, 57 g of the first run obtained in Example 1 was further added, and the separable flask was kept in the liquid-liquid separation tank while the evaporated liquid was kept in Example 1. Distillation was performed in the same manner as in Example 1 until the bottom temperature of the flask was raised and the distillation was continued until the temperature reached 67.3 ° C. to obtain a main distillation.

  Specifically, 300 g of the filtrate described above and 57 g of the first fraction obtained in Example 1 were charged into a separable flask. Moreover, the liquid-liquid separation tank kept the evaporation liquid collected in Example 1, and the liquid-liquid separation tank was 15 degreeC. Distillation was performed by reducing the pressure in the plate column from normal pressure to 133 kPa and raising the bottom temperature of the separable flask from room temperature to 60.4 ° C. The evaporated liquid distilled into the liquid-liquid separation tank was separated into two phases into a lower phase mainly composed of water and an upper phase mainly composed of methyl isobutyl ketone. Here, the lower phase stayed in the liquid-liquid separation tank, but the upper phase overflowed and returned to the tray column. After the interface between the lower phase and the upper phase gradually rises and the top temperature of the plate tower rises, the temperature rise of the top temperature of the plate tower becomes dull at around 57.7 ° C. The rise of the upper phase interface also stopped.

  The line connecting the plate tower and the liquid-liquid separation tank is switched from the liquid-liquid separation tank to the first distillation tank, and the top temperature of the plate tower is around 58.2 ° C as the concentration of water contained in the evaporation component decreases. The total distillation was carried out until the temperature rise slowed to obtain 60 g of the first fraction. Here, as a result of analyzing the concentration of methyl isobutyl ketone contained in the first fraction by gas chromatography, it was 98.0% by weight.

  With the reflux ratio set to 2, the line connecting the column tower and the first distillation tank is switched to the main distillation tank, the bottom temperature of the separable flask is raised, and the distillation is continued until it reaches 67.3 ° C. Obtained. The concentration of methyl isobutyl ketone contained in the main distillate was analyzed by gas chromatography and found to be 99.9% by weight. Moreover, the water contained in the main fraction was 0.1% by weight by the moisture meter, and the hydrogen chloride contained in the main fraction was below the detection limit by the potentiometric titrator. Therefore, the recovery rate of methyl isobutyl ketone in the main distillate was calculated as (202 g × 0.999) ÷ (300 g × 0.740 + 57 g × 0.980) × 100 = 73%. The recovery rate of methyl isobutyl ketone in the total distillate obtained by adding the recovery of methyl isobutyl ketone in the initial distillation is (60 g × 0.980 + 202 g × 0.999) ÷ (300 g × 0.740 + 57 g × 0 .980) × 100 = 94%.

[Comparative Example 1]
Example 1 is the same as Example 1 except that the line from the plate tower is connected to the first distillation tank.
A batch distillation tower was installed in the same manner as described above.
The separable flask was charged with 300 g of the filtrate described above. Distillation was performed by setting the reflux ratio to 2, reducing the pressure in the plate column from normal pressure to 133 kPa, and raising the bottom temperature of the separable flask from room temperature to 60.4 ° C. As water evaporates with methyl isobutyl ketone, the top temperature of the plate tower rises, and as the concentration of water contained in the evaporating component decreases, the temperature rise becomes slow at around 58.2 ° C. All distillates were obtained to obtain 131 g of the first fraction. Here, as a result of analyzing the concentration of methyl isobutyl ketone contained in the first fraction by gas chromatography, it was 92.0% by weight.

  While maintaining the reflux ratio at 2, the line connecting the column tower and the first distillation tank is switched to the main distillation tank, the bottom temperature of the separable flask is raised, and the distillation is continued until the temperature reaches 67.3 ° C. Got. The concentration of methyl isobutyl ketone contained in the main distillate was analyzed by gas chromatography and found to be 99.9% by weight. Moreover, the water contained in the main fraction was 0.1% by weight by the moisture meter, and the hydrogen chloride contained in the main fraction was below the detection limit by the potentiometric titrator. Therefore, the recovery rate of methyl isobutyl ketone in the main distillate was calculated as (79 g × 0.999) ÷ (300 g × 0.740) × 100 = 36%.

The first distillate and the main distillate were mixed at a weight ratio of 131 pairs of the first distillate and the main distillate 79 to obtain a total distillate. The water contained in the total distillate was 5.0% by weight with a moisture meter, and the hydrogen chloride contained in the total distillate was 0.1% by weight with a potentiometric titrator.
Table 1 summarizes the composition of main fractions in Examples 1 and 2 and Comparative Example 1, the recovery rate of methyl isobutyl ketone (MIBK) in the main distillate, and the recovery rate of methyl isobutyl ketone (MIBK) in all distillates. From the results of Table 1, it was confirmed that the polar organic solvent used for recovering the catalyst used for the production of diphenyl carbonate by the decarbonylation reaction of diphenyl oxalate can be easily and efficiently recovered by the catalyst recovery method of the present invention. .

[Example 3]
Catalyst recovery was performed using the main distillate obtained in Example 2.
Specifically, in an eggplant-shaped flask equipped with a stir bar, 27 g (0.11 mol) of diphenyl oxalate and 4-t-butylphenyltriphenylphosphonium chloride hydrogen chloride salt synthesized in Synthesis Example 1 (molecular weight 467) 16 g was put and immersed in an oil bath at 240 ° C. The temperature of the oil bath was raised to 240 ° C. and reacted for 2 hours.

After the reaction, a distillation tube was attached to the eggplant-shaped flask, and 2 g of a mixture of diphenyl carbonate and phenol was distilled under a full vacuum with a diaphragm pump. After the obtained residue was cooled to 100 ° C., 80 g of the main fraction obtained in Example 2 was added to obtain a white slurry. The slurry was cooled to room temperature (about 20 ° C.) and hydrogen chloride gas (molecular weight 36) 0.001 m.
³ (hydrogen chloride 0.04 mol with respect to 1 mol of 4-t-butylphenyltriphenylphosphonium chloride contained in the reaction solution) was bubbled and absorbed. As a result, a visually uniform solution was obtained. When 4 g of water was added to this solution over 30 minutes, a white slurry was formed again. The slurry obtained by filtering this slurry under reduced pressure was overwashed with 10 g of methyl isobutyl ketone, and then filtered under reduced pressure to obtain 18 g of a solid.

  The filterability of the obtained solid under reduced pressure filtration was good. Moreover, when the composition of this solid was analyzed by high performance liquid chromatography, the concentration of 4-t-butylphenyltriphenylphosphonium chloride was 76% by weight. Therefore, the recovery rate of 4-t-butylphenyltriphenylphosphonium chloride (molecular weight 431) recovered as a solid was calculated as (18 g × 0.76 ÷ 431) ÷ (16 g ÷ 467) × 100 = 93%. . In addition, when analyzed by high performance liquid chromatography, phenol was below the detection limit.

[Comparative Example 2]
In Example 3, catalyst recovery was performed in the same manner as in Example 3 except that 80 g of the total distillate obtained in Comparative Example 1 was used instead of 80 g of the main distillate obtained in Example 2. However, the white slurry to which all the distillate had been added was cooled to room temperature (about 20 ° C.) and absorbed by lubbling 1 liter of hydrogen chloride gas, but it did not become a uniform liquid visually.

[Reference Example 1]
Water was added to methyl isobutyl ketone manufactured by Wako Pure Chemical Industries, Ltd. to prepare a water concentration of 0.3% by weight. In Example 3, catalyst recovery was performed in the same manner as in Example 3 except that methyl isobutyl ketone having a water concentration of 0.3% by weight was used instead of the main fraction obtained in Example 2. However, the white slurry to which all the distillate had been added was cooled to room temperature (about 20 ° C.) and absorbed by bubbling 1 liter of hydrogen chloride gas. did not become. 4 g of water was added to this solution over 30 minutes, and then the solid obtained by filtration under reduced pressure was washed with 10 g of methyl isobutyl ketone, followed by filtration under reduced pressure to obtain 18 g of a solid.

  When the composition of the obtained solid was analyzed by high performance liquid chromatography, the concentration of 4-t-butylphenyltriphenylphosphonium chloride was 77% by weight. Therefore, the recovery rate of 4-t-butylphenyltriphenylphosphonium chloride was calculated as (18 g × 0.77 ÷ 431) ÷ (16 g ÷ 467) × 100 = 94%. However, when this solid was analyzed by high performance liquid chromatography, 3% by weight of phenol was detected.

  Table 2 summarizes the water concentration in methyl isobutyl ketone (MIBK) used for catalyst recovery and the recovery rate of 4-t-butylphenyltriphenylphosphonium chloride in Example 3, Comparative Example 2, and Reference Example 1. From Table 2, it was confirmed that the polar organic solvent used for catalyst recovery preferably has a low water concentration, and particularly preferably has a water concentration of 0.3% by weight or less.

[Example 4]
A decarbonylation reaction was performed using the recovered catalyst obtained in Example 3.
First, 10 g of the solid obtained in Example 3 was placed in a 100 cm ³ eggplant-shaped flask, attached to a rotary evaporator equipped with an oil bath, and dried for 1 hour under a full vacuum with an oil bath temperature of 140 ° C. and a diaphragm pump.

5 g of the dried solid and 95 g (0.4 mol) of diphenyl oxalate were placed in a 500 cm ³ eggplant-shaped flask equipped with a stir bar, and immersed in an oil bath at 230 ° C. for 1 hour.
The liquid composition after the reaction was analyzed by high performance liquid chromatography. As a result, 66.0% by weight of diphenyl carbonate, 28.6% by weight of diphenyl oxalate, 5.0% by weight of 4-t-butylphenyltriphenylphosphonium chloride, phenol 0 4% by weight was included.

[Reference Example 2]
In Example 4, instead of the dried solid obtained in Example 3, 5 g of 4-t-butylphenyltriphenylphosphonium chloride hydrogen chloride synthesized in Synthesis Example 1 was used. Similarly, decarbonylation reaction was performed. The liquid composition after the reaction was analyzed by high performance liquid chromatography. As a result, 65.4% by weight of diphenyl carbonate, 29.2% by weight of diphenyl oxalate, 5.0% by weight of 4-t-butylphenyltriphenylphosphonium chloride, phenol 0 .4% by weight.

By comparing the liquid composition after the reaction in Example 4 and Reference Example 2, even if the polar organic solvent used for catalyst recovery is reused to recover the catalyst, high-purity diphenyl carbonate can be efficiently and stably obtained. It was confirmed that it could be manufactured.
As described above, according to the catalyst recovery method of the present invention, the recovered catalyst can be reused and the solvent used for catalyst recovery can be reused to efficiently and stably produce high-purity diphenyl carbonate. It was supported.

Claims (8)

  A method for recovering a catalyst used in the production of diphenyl carbonate by decarbonylation of diphenyl oxalate, wherein the catalyst is a tetraarylphosphonium halide and / or an adduct of a tetraarylphosphonium halide and a hydrogen halide, The residual liquid obtained from the reaction liquid after the carbonyl reaction is contacted with a polar organic solvent and hydrogen chloride, and then the catalyst contained in the residual liquid is recovered (catalyst recovery step) and the polar organic A method for recovering a catalyst, wherein the solvent is recovered and reused in the catalyst recovery step. The method for recovering a catalyst according to claim 1, wherein the polar organic solvent used for recovering the catalyst is purified by performing the following steps (A) and (B) in this order, and then reused. And a catalyst recovery method.
(A) Step: The polar organic solvent used for the catalyst recovery is evaporated and distilled into a liquid-liquid separator containing water, and the polar organic solvent phase of the liquid-liquid separator is moved to the residual liquid side. Removing at least part of the hydrogen chloride contained in the residual liquid by returning,
(B) Process: The process of distilling the liquid obtained at the (A) process.   The method for recovering a catalyst according to claim 1 or 2, wherein the catalyst is an asymmetric tetraarylphosphonium halide and / or an adduct of an asymmetric tetraarylphosphonium halide and a hydrogen halide.   The catalyst recovery method according to any one of claims 1 to 3, wherein the polar organic solvent and hydrogen chloride are brought into contact with the residual liquid, and the residual liquid is brought into contact with the polar organic solvent, and then chlorinated. A method for recovering a catalyst, comprising contacting with hydrogen.   The catalyst recovery method according to any one of claims 1 to 3, wherein the polar organic solvent and hydrogen chloride are brought into contact with the residual liquid after the polar organic solvent and hydrogen chloride are brought into contact with each other. A method for recovering a catalyst, comprising bringing the residual liquid into contact therewith.   A method for producing diphenyl carbonate by decarbonylation of diphenyl oxalate, wherein the catalyst recovered by the recovery method according to any one of claims 1 to 5 is used as a catalyst. Production method. A process for continuously producing diphenyl carbonate comprising a step of decarbonylating diphenyl oxalate, comprising the following first to fourth steps in this order.
1st process: The process which produces | generates a diphenyl carbonate by carrying out the decarbonylation reaction of diphenyl oxalate in presence of the tetraaryl phosphonium halide and / or the adduct body of the tetraaryl phosphonium halide and hydrogen halide,
2nd process: The process of isolate | separating the component containing diphenyl carbonate from the reaction liquid obtained at the 1st process,
Third step: A step of precipitating the catalyst contained in the residual liquid from which the component containing diphenyl carbonate has been separated in the second step (here, the third step includes adding a polar organic solvent and hydrogen chloride to at least a part of the residual liquid. Having a step of contacting),
Fourth step: A step of supplying at least a part of the precipitate obtained in the third step to the first step as a catalyst for the decarbonylation reaction. A method for producing a polycarbonate by polycondensation of diphenyl carbonate and a dihydroxy compound in the presence of a transesterification catalyst, wherein the diphenyl carbonate is produced by the method for producing diphenyl carbonate according to claim 6 or the method according to claim 7. A method for producing a polycarbonate, which is produced by a continuous production method of diphenyl carbonate and then polycondensed with the dihydroxy compound.