JP3409604B2 - Method for producing diaryl carbonate - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a diaryl carbonate useful as a raw material for producing polycarbonate.

[0002]

As a method for producing a diaryl carbonate, a method of reacting phosgene with an aromatic hydroxy compound in the presence of an alkali (JP-A-62-190146).
Or the like) or a method of transesterifying a dialkyl carbonate and an aromatic hydroxy compound in the presence of a catalyst (Japanese Patent Publication No. 56-42577, Japanese Patent Publication No. 1-558).
No. 8, etc.) are well known. However, the former method using phosgene is not necessarily an industrially excellent method because phosgene itself is a highly toxic compound and a large amount of alkali is used. Also, the latter transesterification method, as described in many patents relating to this method, does not have a sufficient reaction rate in spite of the use of a highly active catalyst, and therefore a large-scale reaction is required to compensate for this. It has a problem that it requires a device.

As another method, there is known a method in which a diaryl oxalate is subjected to a decarbonylation reaction to produce a diaryl carbonate. In this method, the selectivity and yield of the diaryl carbonate are low and the reaction temperature is high. Therefore, it has a problem that it is industrially very disadvantageous. For example, a method of producing diphenyl carbonate by boiling diphenyl oxalate in a distillation flask in the absence of a catalyst [Organic Synthesis Society, 5, Report 47 (1)
948), 70], there is no catalyst and the reaction temperature is high, so that phenol and carbon dioxide are by-produced, and the selectivity and yield of diphenyl carbonate are remarkably reduced. Conversely, when the reaction temperature is low, diphenyl carbonate is almost eliminated. There is a problem that you cannot get it.

Further, a method for producing a dialkyl carbonate by heating a dialkyl oxalate or the like in the liquid phase at 50 to 150 ° C. in the presence of an alcoholate catalyst (USP45
However, according to the examples described in this publication, even if diphenyl oxalate is heated in the presence of a potassium phenoxide catalyst, the main product is diphenyl oxalate. Is. As described above, a highly active and highly selective catalyst capable of producing a diaryl carbonate from a diaryl oxalate is not known, and further, the catalyst is recovered to have a high activity,
No method is known that can be reused in the highly selective state.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing a diaryl carbonate for a long period of time by using a highly active and highly selective catalyst without using phosgene which is a highly toxic compound. Is an issue. That is, in a method for producing a diaryl carbonate from a diaryl oxalate, particularly in a method for producing a diaryl carbonate by decarbonylating a diaryl oxalate in the presence of an organic phosphonium salt, while recovering and reusing the organic phosphonium salt, An object of the present invention is to provide a method capable of producing a diaryl carbonate over a long period of time with high selectivity.

[0006]

The problems of the present invention are (1)
In the first step, the diaryl oxalate is subjected to a decarbonylation reaction in the presence of an organic phosphonium salt to produce a diaryl carbonate, (2) in the second step, the diaryl carbonate is recovered from the reaction solution, and (3) the third step. In the presence of its residue containing an organic phosphonium salt,
A halogen compound is added to carry out a decarbonylation reaction of the diaryl oxalate to produce a diaryl carbonate, and in (4) the fourth step, the residue containing the organic phosphonium salt is extracted from the reaction system, and the organic compound is extracted from the residue. A phosphonium salt is recovered by extraction with water, and (5) in the fifth step, the recovered organic phosphonium salt is reused in the decarbonylation reaction of the diaryl oxalate in the third step. And a method for recovering the organic phosphonium salt, which comprises extracting the organic phosphonium salt from the residue with water.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A diaryl carbonate is produced by a decarbonylation reaction of a diaryl oxalate represented by the following formula.

[0008]

[Chemical 1] (In the formula, Ar represents an aryl group.)

In the present invention, the organic phosphonium salt is recovered and reused as a catalyst in the decarbonylation reaction of diaryl oxalate. That is, in the present invention, a residue containing an organophosphorus compound, which is obtained by recovering the diaryl carbonate from the reaction solution in the reaction of decarbonylating the diaryl oxalate in the presence of the organic phosphonium salt to produce the diaryl carbonate, The organic phosphonium salt is efficiently recovered from the product and reused as a highly active and highly selective catalyst. In particular, in the present invention, the diaryl oxalate is decarbonylated in the presence of an organic phosphonium salt to produce a diaryl carbonate, the produced diaryl carbonate is recovered by distillation or the like, and then the residue containing the organic phosphonium salt is used as a catalyst. In a continuous production process of a diaryl carbonate in which the diaryl oxalate is subjected to a decarbonylation reaction to produce a diaryl carbonate by circulation, the organic phosphonium salt is efficiently recovered from the residue containing the organic phosphonium salt extracted from the reaction system. Reused as a highly active, highly selective catalyst.
Hereinafter, the present invention will be described in detail.

In the diaryl oxalate used in the present invention, the aryl group is (1) phenyl group, (2) (a) alkyl group having 1 to 12 carbon atoms such as methyl group and ethyl group, (b) Alkoxy groups having 1 to 12 carbon atoms such as methoxy group and ethoxy group, (c) halogen atoms such as fluorine atom and chlorine atom, or (d) substituted phenyl group having a substituent such as nitro group, or (3) naphthyl. Compounds such as groups. Of these aryl groups, the phenyl group is preferred.

The above-mentioned substituted phenyl group includes various isomers. These isomers include (a) 2- (or 3-, 4)
-) A methylphenyl group, a 2- (or 3-, 4-) ethylphenyl group or the like having 1 to 2 carbon atoms at the 2- (or 3-, 4-) position.
An alkyl-substituted phenyl group having 12 alkyl groups,
(B) 2- (or 3-, 4-) methoxyphenyl group, 2
An alkoxy-substituted phenyl group having an alkoxy group having 1 to 12 carbon atoms at the 2- (or 3-, 4-) position such as a-(or 3-, 4-) ethoxyphenyl group, (c) 2- (or 3)
-, 4-) fluorophenyl group, 2- (or 3-, 4)
-) A halogen-substituted phenyl group having a halogen atom at the 2- (or 3-, 4-) position such as a chlorophenyl group, (d)
2- (or 3-, 4-) nitrophenyl group, etc. are mentioned.

As the diaryl oxalate, diphenyl oxalate, bis (2-methylphenyl) oxalate, bis (3-methylphenyl) oxalate, bis (4-methylphenyl) oxalate, bis (2-chlorophenyl) oxalate, bis ( Specific examples include 3-chlorophenyl) oxalate, bis (4-chlorophenyl) oxalate, bis (2-nitrophenyl) oxalate, bis (3-nitrophenyl) oxalate, and bis (4-nitrophenyl) oxalate. Moreover, other diaryl oxalates are synthesized based on known methods. Of these diaryl oxalates, diphenyl oxalate is preferred.

The organic phosphonium salt used in the present invention is represented by the following general formula.

[Chemical 2] (In the formula, R ¹ , R ² , R ³ , and R ⁴ are an aryl group having 6 to 14 carbon atoms, an alkyl group having 1 to 16 carbon atoms, and 7 to 2 carbon atoms.
2 represents an aralkyl group, a heterocyclic group having 4 to 16 carbon atoms, or an aryloxy group having 6 to 14 carbon atoms, and X represents an atom or an atomic group capable of forming a counterion of the phosphonium salt.
Further, these groups may be the same as or different from each other, and may be bridged between the two groups to form a ring containing a phosphorus atom. )

Examples of the aryl group, alkyl group, aralkyl group, heterocyclic group and aryloxy group represented by R ¹ , R ² , R ³ and R ⁴ include the following. That is, examples of the aryl group include an aryl group having a carbon number of 6 to 14, such as a phenyl group and a naphthyl group, which may have a substituent, and the alkyl group may have a substituent. , A methyl group, an ethyl group, an n- (or i-) propyl group, an n- (or i-, sec-, tert-) butyl group, and the like, and an alkyl group having 1 to 16 carbon atoms. A benzyl group, a phenethyl group, a naphthylmethyl group or the like, which may have a substituent, having 7 to 2 carbon atoms.
2 aralkyl groups, and examples of the heterocyclic group include a heterocyclic group having 4 to 16 carbon atoms, which may have a substituent, such as a thienyl group, a furyl group and a pyridyl group, and an aryloxy group. Examples include aryloxy groups having 6 to 14 carbon atoms, which may have a substituent, such as phenoxy group and naphthoxy group.

The above-mentioned aryl group, aralkyl group, heterocyclic group and aryloxy group have an alkyl group having 1 to 15 carbon atoms, an alkoxy group having 1 to 15 carbon atoms or 2 carbon atoms on the aromatic ring or heterocyclic ring. To an alkoxycarbonyl group, a C6 to C14 aryl group, a C2 to C16 N, N-dialkyl-substituted amino group, and other amino groups, a cyano group, a nitro group, a halogen atom such as fluorine, chlorine, and bromine. May have one or more various substituents such as (including various isomers of o, m, p, etc.). The alkyl group is an alkoxy group having 1 to 15 carbon atoms or 2 carbon atoms.
1 to 12 or more various substituents such as an alkoxycarbonyl group having 1 to 12 carbon atoms, an amino group having 2 to 16 carbon atoms such as an N, N-dialkyl-substituted amino group, a cyano group, a nitro group, a halogen atom such as fluorine, chlorine and bromine. You can have it.

Examples of the organic phosphonium salt include R
Those in which all of ¹ , R ² , R ³ and R ⁴ are aryl groups (tetraarylphosphonium salt), R ¹ , R ² and R 4
^Three of R ³ and R ⁴ are aryl groups and one is another group, and ^{2 of} R ¹ , R ² , R ³ and R ⁴
One is an aryl group and two are different groups,
^{One in which one of} R ¹ , R ² , R ³ , and R ⁴ is an aryl group and three are other groups; and R ¹ , R ² , R ³ ,
Those in which none of R ⁴ is an aryl group can be mentioned.

Among these organic phosphonium salts,
Those in which all of R ¹ , R ² , R ³ and R ⁴ are aryl groups (tetraarylphosphonium salts), R ¹ , R ² and R 4
It is preferable that ^three of R ³ and R ⁴ are aryl groups and one of them is a heterocyclic group, but among them, R ¹ , R ² ,
Those in which all of R ³ and R ⁴ are aryl groups (tetraarylphosphonium salt) are preferable.

The pair of the organic phosphonium salt ions X ^- include the halogen ion (chloride ion, bromide ion, iodide ion, etc.) and, hydrogen dihalide ion (hydrogen dichloride ion, hydrogen dibromide ion, hydrogen di Yoda Id ion, hydrogen bromide chloride ion, etc., halogenate ion (chlorate ion, bromate ion, iodate ion, etc.), perhalogenate ion (perchlorate ion,
Perbromate ion, periodate ion, etc.), aliphatic carboxylate ion (acetate ion, trifluoroacetate ion,
Propionate ion, etc.), aromatic carboxylate ion (benzoate ion, α- (or β-) naphthalenecarboxylate ion, etc.), aromatic hydroxy ion (phenoxide ion, etc.), inorganic acid ion (sulfate ion, etc.) , Hydrogen sulfate ion, phosphate ion, hydrogen phosphate ion, borate ion, hydrogen borate ion, cyanate ion, thiocyanate ion, fluoroborate ion, etc., and tetraalkyl borate ion (tetramethyl borate ion, tetraethyl borate ion) Etc., etc., having an alkyl group having 1 to 10 carbon atoms), a tetraaryl borate ion (having an aryl group having 6 to 14 carbon atoms such as tetraphenyl borate ion, tetrakis-p-fluorophenyl borate ion), an alkyl sulfone Acid or alkylsulfinate ion (methyl group, ethyl group, n- ( Or i-) having an alkyl group having 1 to 16 carbon atoms such as a propyl group), arylsulfonic acid or arylsulfinate ion (phenyl group, p
-Having a toluyl group, an aryl group such as a p-nitrophenyl group) and the like. Among these counter ions X ⁻ , halogen ions and hydrogen dihalide ions are preferable, but chlorine ions and hydrogen dichloride ions are particularly preferable.

Specific examples of the organic phosphonium salt include the following compounds. R ¹ , R ² , R
Examples of the phosphonium salt in which all of R ³ and R ⁴ are aryl groups and X ⁻ is a halogen ion include, for example, tetraphenylphosphonium chloride, tetraphenylphosphonium bromide, tetraphenylphosphonium iodide, and tetrakis (p-chlorophenyl) phosphonium. Chloride, tetrakis (p-fluorophenyl) phosphonium chloride, tetrakis (p-tolyl) phosphonium chloride, p-chlorophenyltriphenylphosphonium chloride, p-chlorophenyltriphenylphosphonium bromide, p-chlorophenyltriphenylphosphonium iodide, p- Tolyltriphenylphosphonium chloride, p-tolyltriphenylphosphonium bromide, p-tolyltriphenylphosphonium ioda De, m- trifluoromethyl or methyl phenyl triphenyl phosphonium chloride, and p- biphenyl triphenyl phosphonium chloride, m- methoxyphenyl triphenyl phosphonium chloride,
p-methoxyphenyltriphenylphosphonium chloride, p-ethoxyphenyltriphenylphosphonium chloride, p-ethoxyphenyltriphenylphosphonium bromide, p-ethoxyphenyltriphenylphosphonium iodide, p-dimethylaminophenyltriphenylphosphonium chloride, p Examples include -ethoxycarbonylphenyltriphenylphosphonium chloride, m-cyanophenyltriphenylphosphonium chloride, 1-naphthyltriphenylphosphonium chloride and 2-thiophenetriphenylphosphonium chloride. Among these organic phosphonium salts, tetraphenylphosphonium chloride is particularly preferable.

Examples of the phosphonium salt in which all of R ¹ , R ² , R ³ and R ⁴ are aryl groups and X ^- is a hydrogen dihalide ion include, for example, tetraphenylphosphonium hydrogen dichloride and tetraphenylphosphonium. Examples thereof include hydrogen dibromide, tetraphenylphosphonium hydrogen diiodide, and tetraphenylphosphonium hydrogen bromide chloride. Among these phosphonium salts, tetraphenylphosphonium hydrogen dichloride is particularly preferable.

A phosphonium salt in which ^{three of} R ¹ , R ² , R ³ and R ⁴ are aryl groups, one is a heterocyclic group, and X ⁻ is a halogen ion is, for example, 2-thiophentritril. Phenylphosphonium chloride may be mentioned.

Examples of the phosphonium salt in which ^{three of} R ¹ , R ² , R ³ and R ⁴ are aryl groups, one is an aryloxy group, and X ^- is a halogen ion include:
Phenoxytriphenylphosphonium chloride may be mentioned.

Among the phosphonium salts, those which are not commercially available can be prepared by known methods [Bull. Chem. Soc. Jp
n. 56, 2869 (1983), J. Am. Che
m. Soc. , 70, 737 (1948)]. For example, tetraarylphosphonium chloride is a triarylphosphine and the corresponding aryl halide (iodo or bromine compound).
Is reacted in the presence of a palladium acetate catalyst, and the obtained tetraarylphosphonium iodide or tetraarylphosphonium bromide is converted to a tetraarylphosphonium chloride by using an ion exchange resin (chlor type). The obtained tetraarylphosphonium chloride is dried at 80 to 200 ° C. for 0.5 to 5 hours under a flow of a dry inert gas such as dry argon gas, and then under a temperature of 0.5 to 5 in this temperature range under a flow of hydrogen chloride gas. It is processed for 2 hours.

The tetraarylphosphonium salt having a counter ion other than a halogen ion is obtained by converting the tetraarylphosphonium chloride obtained as described above into an alkali metal salt (sodium salt, potassium salt, etc.) or ammonium having a corresponding counter ion. Reaction with salt (ion exchange)
It is synthesized by Other phosphonium salts other than the tetraarylphosphonium salt are synthesized by the same method.

Among the organic phosphonium salts used in the present invention, tetraarylphosphonium halides and tetraarylphosphonium hydrogendihalides are preferable, and tetraarylphosphonium chloride and tetraarylphosphonium hydrogendichloride are particularly preferable.

Examples of the halogen compound used in the present invention include the following inorganic halogen compounds and / or organic halogen compounds. Among these halogen compounds, chlorine compounds or bromine compounds are preferable, and chlorine compounds are particularly preferable.

Examples of the inorganic halogen compound include phosphorus halides such as phosphorus trichloride, phosphorus pentachloride, phosphorus oxychloride, phosphorus tribromide, phosphorus pentabromide and phosphorus oxybromide, and thionyl chloride, sulfuryl chloride and dichloride. Sulfur chlorides such as sulfur chloride and dichloride, sulfur halides such as hydrogen chloride and hydrogen bromide, and simple halogens such as chlorine and bromine are used. Among these inorganic halogen compounds, the above inorganic chlorine compounds are preferable.

The organic halogen compound is, for example, a structure (C-Ha) in which a halogen atom is bonded to saturated carbon.
l) or a structure in which a halogen atom is bonded to a carbonyl carbon (-CO-Hal), (wherein Hal is a chlorine atom,
Represents a halogen atom such as a bromine atom. An organic halogen compound having a) is preferably used. These structures are represented by, for example, the following general formulas (a) and (b).

[0029]

[Chemical 3] (In the formula, Hal represents a halogen atom such as a chlorine atom and a bromine atom, and n represents an integer of 1 to 4.)

As such an organic halogen compound,
For example, the following compounds are specifically mentioned. Examples of the organic halogen compound represented by the general formula (a) having a structure in which a halogen atom is bonded to a saturated carbon include halogenated compounds such as chloroform, carbon tetrachloride, 1,2-dichloroethane, butyl chloride, dodecyl chloride. Alkyl, aralkyl halides such as benzyl chloride, benzotrichloride, triphenylmethyl chloride, α-bromo-o-xylene, and halogen-substituted aliphatic nitriles such as β-chloropropionitrile and γ-chlorobutyronitrile, , Halogen-substituted aliphatic carboxylic acids such as chloroacetic acid, bromoacetic acid, and chloropropionic acid.

Examples of the organic halogen compound represented by the general formula (b) having a structure in which a halogen atom is bonded to a carbonyl carbon include acetyl chloride, oxalyl chloride, propionyl chloride, stearoyl chloride, benzoyl chloride,
Examples thereof include acid halides such as 2-naphthalenecarboxylic acid chloride and 2-thionephencarboxylic acid chloride, halogenoglyoxylic acid aryls such as phenylchloroglyoxylate, and halogenoformate aryls such as phenylchloroformate. Among these organic halogen compounds, the above organic chlorine compounds in which the halogen atom is a chlorine atom are preferable.

The production of the diaryl carbonate of the present invention includes (1) a first step (dearyl carbonate producing step) of decarbonylating a diaryl oxalate in the presence of an organic phosphonium salt to produce a diaryl carbonate, (2) Second step of recovering diaryl carbonate from the reaction solution (diaryl carbonate recovery step), (3) In the presence of the residue containing an organic phosphonium salt, the halogen compound is added to decarbonylate the diaryl oxalate. Third step of producing a diaryl carbonate (diaryl carbonate production step), (4) The residue containing the organic phosphonium salt is extracted from the reaction system, and the organic phosphonium salt is extracted from the residue with water and recovered. Process (organic phosphonium salt recovery work ) Is performed by (5) Fifth step of reusing the recovered organic phosphonium salt decarbonylation reaction of diaryl oxalate in the third step (diaryl carbonate production step). In the present invention,
Usually, the first to third steps are continuously performed, and then the second step and the third step are repeated, and the fourth step and the fifth step are performed.
The process is carried out continuously or batchwise. Hereinafter, the method of the present invention will be described in more detail.

The decarbonylation reaction of the diaryl oxalate (first step; diaryl carbonate production step) is
The reactor is charged with the diaryl oxalate and the organic phosphonium salt, and optionally with the above-mentioned halogen compound, and is usually 100 to 450 ° C., preferably 160 to 4
It is carried out in a batch or continuous liquid phase reaction by heating at 00 ° C, more preferably 180 to 350 ° C. At this time, according to the above reaction formula, diaryl carbonate is produced from diaryl oxalate and carbon monoxide is produced. The reaction pressure is not particularly limited, and the reaction may be performed under any of increased pressure, normal pressure and reduced pressure. The residence time of the reaction solution is usually 0.5 to 10
The time is preferably about 1 to 5 hours, and the conversion rate of the diaryl oxalate at that time is 30 to 100%.

In the present invention, the halogen compound may be added in the first step, if necessary. In particular, as the organic phosphonium salt, when an organic phosphonium salt other than halide and hydrogen dihalide is used, or when a low concentration of phosphonium halide or phosphonium hydrogen dihalide is used, add a halogen compound. Is preferred. Further, when the diaryl carbonate is produced by a continuous process as described below, it is preferable to add the halogen compound from the first step.

In the first step, the organic phosphonium salt is usually used in an amount of 0.001 to 50 mol%, preferably 0.01 to 20 mol% based on the diaryl oxalate. The organic phosphonium salts may be used alone or in combination of two or more kinds, and may be dissolved and / or suspended in the reaction solution before use. When the above halogen compound is added, the halogen compound is added so that the molar ratio (halogen compound / organic phosphonium salt) to the organic phosphonium salt is usually 0.01 to 300, preferably 0.1 to 100. . The halogen compounds may be used alone or in combination of two or more.

A solvent is not particularly required for the decarbonylation reaction of diaryl oxalate, but if necessary, diphenyl ether, sulfolane, N-methylpyrrolidone,
Dimethyl imidazolidone, 1,3-dimethyl-3,4
A solvent such as 5,6-tetrahydro-2 (1H) -pyrimidinone can be appropriately used. The material of the reactor is not particularly limited, and for example, a glass or stainless steel (SUS) reactor can be used.
Further, the reactor may be one tank or multiple tanks.

After the reaction, the produced diaryl carbonate is recovered, for example, by distillation from the reaction liquid which is wholly or partially withdrawn from the reactor (second step; diaryl carbonate recovery step). In order to recover the diaryl carbonate, the residue containing the catalyst (organic phosphonium salt) is separated by an evaporator or thin film evaporator, and then this evaporated portion (including the diaryl carbonate and unreacted diaryl oxalate) is removed to some extent. Number of theoretical plates (especially 5-5
A general method of distilling using a packed column having 0 stages) or a distillation column is preferably used. Further, a method is also used in which the reaction liquid is distilled in the packed column or the distillation column described above to extract the diaryl carbonate from the top of the column and the residue containing the organic phosphonium salt from the bottom of the column. Distillation
For example, under reduced pressure of 2 to 100 mmHg, tower bottom temperature 150
~ 250 ° C, tower top temperature 80-200 ° C, preferably 10
It is performed under the condition of 0 to 180 ° C. By such a method, the diaryl carbonate contained in the reaction liquid extracted from the reactor is recovered.

The amount of the organic phosphonium salt-containing residue obtained by recovering the diaryl carbonate is usually 1 to 20% by weight of the reaction solution, preferably 1 to 10% by weight. Almost 100% of the organic phosphonium salt contained in the reaction liquid extracted from the reaction solution was contained, and unreacted diaryl oxalate and unrecovered diaryl carbonate were contained. The residue containing the organophosphorus compound is used as a catalyst for the decarbonylation reaction of diaryloxalate (third step). In addition to being used as a catalyst, the residue is partially or wholly extracted from the reaction system continuously or batchwise in order to prevent accumulation of high boiling substances and the like. Then, the organic phosphonium salt is recovered from the extracted residue by water extraction (fourth step).

Then, the residue containing the organic phosphonium salt is used as a catalyst to carry out the decarbonylation reaction of the diaryl oxalate (third step; diaryl carbonate production step). In the third step, the diaryl oxalate and the residue containing the organic phosphonium salt are placed in a reactor, the halogen compound is further added, and the decarbonylation reaction is performed under the same reaction conditions as in the first reaction step. Be seen. At this time, when the entire amount of the reaction liquid is extracted from the reactor in the second step, the residue containing the organic phosphonium salt contains almost the entire amount of the used organic phosphonium salt, and therefore, it is used as a catalyst in the third step as it is. To be done. On the other hand, when the reaction solution is partially withdrawn from the reactor in the second step, since this residue contains only a part of the used organic phosphonium salt, it depends on the withdrawal amount of the reaction solution. In order to supplement the shortage and keep the concentration of the organic phosphonium salt within a certain range, a necessary amount of the organic phosphonium salt is newly added in the third step. Diaryl oxalate usually has a high conversion in the first step, and is separated as an evaporated component in the second step, and only a small amount is contained in the residue containing the organic phosphonium salt. It is added as in the first step. The halogen compound is
It is added in the third step in the same ratio as in the case of adding the halogen compound in the first step.

After the diaryl carbonate is recovered from the reaction solution as described above, the organic phosphonium which is continuously or batchwise extracted from the reaction system (that is, the organic phosphorus compound circulating system between the first to third steps). From the residue containing salt,
Organic phosphonium salts are recovered by water extraction (4th
Process; organic phosphonium salt recovery process). The organic phosphonium salt is recovered by adding water (preferably deionized water) to the residue containing the organic phosphonium salt extracted from the reaction system in an amount of 0.1 to 100 times by weight, preferably 1 to 50 times by weight, This is carried out by stirring this so as to form a uniform slurry or suspension, transferring the organic phosphonium salt to the aqueous phase (water extraction), and then recovering the organic phosphonium salt from this aqueous phase.

This extraction operation can be carried out in the temperature range from room temperature to the reaction temperature of the decarbonylation reaction. However, when it is carried out at a temperature at which the residue solidifies, water is added to the residue and the mixture is stirred at high speed with a homogenizer or the like. However, it is preferable to homogenize and extract. It should be noted that this extraction operation is usually 5 minutes to
One hour, preferably about 5 to 30 minutes, is sufficient. After completion of the extraction operation, the obtained slurry or suspension is cooled to room temperature if necessary, and then the insoluble matter is removed from the slurry or suspension by filtration or centrifugation.
The obtained aqueous phase is concentrated to dryness, and the dried product is dried by heating, whereby the organic phosphonium salt is efficiently recovered. At this time, the heat drying is performed at 120 to 180 ° C. for 1 to 3 hours under a flow of an inert gas such as argon.

In the above extraction operation, in addition to water,
An organic solvent such as an aromatic hydrocarbon such as toluene or an aliphatic halogenated hydrocarbon such as chloroform, methylene chloride or 1,2-dichloroethane can also be used in combination. These organic solvents are usually used in an amount of 0.01 to 100 times by volume, preferably 0.1 to 10 times by volume, relative to water. In this case, the insoluble matter is dissolved in an organic solvent, and a liquid separated into an aqueous phase and an organic phase is obtained after completion of the extraction operation. Therefore, the liquid can be separated to obtain an aqueous phase. In the present invention, in this way, the organic phosphonium salt that can be used as a highly active and highly selective catalyst can be efficiently recovered from the residue containing the organic phosphonium salt.

The organic phosphonium salt recovered in the fourth step is reused in the decarbonylation reaction in the third step (fifth step).
Step; diaryl carbonate production step). That is, the fifth
The step uses the organic phosphonium salt recovered in the fourth step as all or part of the organic phosphorus compound newly replenished to replenish the deficiency in the reaction in the third step. In the fifth step, the reactor was charged with the diaryl oxalate, the organic phosphonium salt recovered in the fourth step, and the halogen compound, and the organic phosphonium salt was replenished as needed to remove the same as in the third step. The carbonyl reaction is carried out. The reaction conditions in the fifth step and the supply amounts of the diaryl oxalate, the halogen compound and the organic phosphonium salt are the same as in the third step.

In the present invention, subsequently, the second step and the third step are repeated, and the fourth step and the fifth step are repeated continuously or batchwise to continuously produce the diaryl carbonate with high selectivity. be able to. At this time, reaction conditions, recovery conditions, extraction conditions and the like are the same as above.

When the diaryl carbonate is continuously produced industrially, a halogen compound is added to the above-mentioned first compound.
~ The third step is carried out continuously, and the second step and the third step
The steps are repeatedly performed, and the fourth step and the fifth step are continuously or batchwise performed. This process will be described according to the flow showing one embodiment of the present invention. Diaryl oxalate through conduit 1, and an organic phosphonium salt and a halogen compound is supplied to the reactor 1 through conduit 2. In the reactor 1 , a decarbonylation reaction of diaryl oxalate is performed, and diaryl carbonate is produced with the generation of carbon monoxide. The generated carbon monoxide is extracted from the gas phase portion of the reactor 1 through the conduit 3. Then, the reaction liquid containing the diaryl carbonate is withdrawn from the bottom of the reactor 1 through the conduit 4 and supplied to the evaporator 2 .

In the evaporator 2 , the residue containing the organic phosphonium salt is separated, withdrawn from the bottom of the evaporator 2 through the conduit 6 and circulated to the reactor 1 . In addition, a part of this residue is extracted from the reaction system through the conduit 7,
It is supplied to the recovery device 4 . On the other hand, the evaporated component containing diaryl carbonate is withdrawn from the top of the evaporator 2 through the conduit 5 and supplied to the distillation column 3 . Then, in the distillation column 3 , the diaryl carbonate is recovered by distillation through the conduit 8. The distillation bottom is withdrawn from the system through the conduit 9.

In the reactor 1 , the residue containing the organic phosphonium salt and the diaryl oxalate which are circulated and supplied through the conduit 6 are supplied through the conduit 1, and the organic phosphorus compound and the halogen compound are within a certain range in the reactor. The organic phosphonium salt and the halogen compound are replenished through the conduit 2 so that the decarbonylation reaction of the diaryl oxalate is continuously performed. The reaction conditions and the like in this step are the same as in the first step.

In the recovery device 4 , water is supplied through the conduit 10 and the organic phosphonium salt is extracted into the aqueous phase. The organic phosphonium salt is then recovered by filtering the aqueous phase withdrawn through conduit 11 if necessary, then concentrating to dryness and drying the resulting dry product (however, each device is not shown). No). The recovered organic phosphonium salt is introduced into the conduit 2 and supplied to the reactor 1 for reuse.

As described above, in the present invention, an organic phosphonium obtained by recovering diaryl carbonate from a reaction solution in a method for producing a diaryl carbonate by decarbonylating a diaryl oxalate in the presence of an organic phosphonium salt. From the residue containing salt,
The organic phosphonium salt can be efficiently recovered. Further, the recovered organic phosphonium salt can be reused as a highly active and highly selective catalyst.

[0050]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples. The conversion rate of diaryl oxalate (the ratio of the consumed diaryl oxalate to the charged diaryl oxalate) and the selectivity of the diaryl carbonate (the ratio of the produced diaryl carbonate to the consumed diaryl oxalate) are on a molar basis (mol%). ).

Example 1 In a 50 ml glass flask equipped with a thermometer and a reflux condenser, 10.010 g of diphenyl oxalate (4
1.23 mmol), and 0.3090 g of tetraphenylphosphonium chloride (0.825 mmol: 2.0 mol% based on diphenyl oxalate),
Add 0.0195 g of chloroform and add 230 with stirring.
After the temperature was raised to 0 ° C., the decarbonylation reaction (first reaction) was carried out at this temperature for 2 hours while removing the generated carbon monoxide outside the system under normal pressure. In addition, tetraphenylphosphonium chloride was used under the flow of dry argon gas to obtain 120
What was heat-processed at 1 degreeC, 1 hour at 150 degreeC, and 1 hour at 180 degreeC, and then cooled to room temperature was used. After completion of the reaction, the reaction solution was cooled to room temperature and analyzed by gas chromatography. As a result, the conversion rate of diphenyloxalate was 95.4% and the selectivity of diphenylcarbonate was 99.0%.

Vacuum distillation (2 to 3 mmHg / bath temperature 185
90% by weight of the reaction solution was distilled off at (° C.) to recover the produced diphenyl carbonate and unreacted diphenyl oxalate. To the residue containing tetraphenylphosphonium chloride obtained by recovering diphenyl carbonate or the like from the reaction solution, the same amounts of diphenyl oxalate and chloroform as described above were added, and a reaction (second reaction) was carried out in the same manner as above. It was As a result, the conversion rate of diphenyl oxalate was 97.0% and the selectivity of diphenyl carbonate was 99.0%.

Thereafter, the same procedure was repeated, and the residue containing tetraphenylphosphonium chloride, which was obtained by recovering diphenyl carbonate from the reaction solution of the decarbonylation reaction, was used as a catalyst three more times (total 5 times).
Reactions). As a result, the conversion of diphenyl oxalate was 95.8% and the selectivity of diphenyl carbonate was 99.0% in the third reaction, and the conversion of diphenyl oxalate was 93.4% and diphenyl carbonate in the fourth reaction. The selectivity was 99.0%, the conversion of diphenyl oxalate was 95.0% and the selectivity of diphenyl carbonate was 99.0% in the fifth reaction.

The reaction liquid of the fifth reaction was distilled under reduced pressure (2 to
(3 mmHg / bath temperature 160 ° C.), and 90% by weight thereof was distilled off to recover diphenyl carbonate from the reaction solution. After cooling the distillation residue containing tetraphenylphosphonium chloride to room temperature, deionized water 50
ml was added, and the mixture was stirred at room temperature for 10 minutes using a homogenizer. Next, the filtrate obtained by suction filtration is concentrated to dryness, and the dried solid is dried by heating under reduced pressure (130 ° C .; 3 hours) to give tetraphenylphosphonium chloride 0.30.
62 g was obtained (recovery rate: 99.1%). To this tetraphenylphosphonium chloride, the same amounts of diphenyl oxalate and chloroform as described above were added, and a reaction (sixth reaction) was carried out in the same manner as described above. As a result, the conversion of diphenyl oxalate was 95.2% and the selectivity of diphenyl carbonate was 99.0%. The results of the reaction are summarized in Table 1.

[0055]

[Table 1]

Example 2 Oxalyl chloride 0.020 instead of chloroform
Except using 7 g, the reaction was performed 5 times in total as in Example 1, and tetraphenylphosphonium chloride was further extracted by water extraction from the distillation residue containing tetraphenylphosphonium chloride and recovered. The sixth reaction was carried out. The results are summarized in Table 2.

[0057]

[Table 2]

Example 3 The amount of diphenyl oxalate was 10.045 g (41.4
Example 1 except that the amount of tetraphenylphosphonium chloride was changed to 0.4612 g (1.230 mmol: 3.0 mol% relative to diphenyl oxalate) and the amount of chloroform was changed to 0.037 g.
The decarbonylation reaction (the first reaction) was performed in the same manner as in, and analysis was performed. As a result, the conversion of diphenyl oxalate was 99.5% and the selectivity of diphenyl carbonate was 99.0%.

This reaction liquid was distilled under reduced pressure in the same manner as in Example 1 to distill off 90% by weight thereof, and diphenyl carbonate was recovered from the reaction liquid. After the distillation residue containing tetraphenylphosphonium chloride was cooled to room temperature, 50 ml of deionized water was added thereto and treated in the same manner as in Example 1 to prepare tetraphenylphosphonium chloride 0.458.
9 g was obtained (recovery rate: 99.5%). To this tetraphenylphosphonium chloride, the same amounts of diphenyl oxalate and chloroform as described above were added, and a reaction (second reaction) was carried out in the same manner as described above. As a result, the conversion of diphenyl oxalate was 99.5% and the selectivity of diphenyl carbonate was 99.0%.

This reaction solution was distilled under reduced pressure in the same manner as described above to distill off 90% by weight of the reaction solution, and diphenyl carbonate was recovered from the reaction solution. Then, a distillation residue containing tetraphenylphosphonium chloride in the same amount as above was used. Diphenyl oxalate and chloroform were added, and the reaction (the third reaction) was performed in the same manner as above. As a result, the conversion of diphenyl oxalate was 99.4% and the selectivity of diphenyl carbonate was 99.0%.

Thereafter, the same procedure is repeated, and the residue containing tetraphenylphosphonium chloride, which is obtained by recovering diphenyl carbonate from the reaction solution, is used as a catalyst as it is, and the reaction is repeated three more times (six times in total). I went. As a result, the conversion of diphenyl oxalate was 99.5% and the selectivity of diphenyl carbonate was 99.0% in the fourth reaction, and the conversion of diphenyl oxalate was 99.4% and diphenyl carbonate in the fifth reaction. The selectivity was 99.0%, the conversion of diphenyl oxalate was 99.4% and the selectivity of diphenyl carbonate was 99.0% in the sixth reaction. The results are summarized in Table 3.

[0062]

[Table 3]

Example 4 Tetraphenylphosphonium chloride was recovered in the same manner as in Example 3 except that the stirring time was changed to 5 minutes to recover 0.4557 g of tetraphenylphosphonium chloride (recovery rate: 98.8). %). When the same amount of diphenyl oxalate and chloroform as in Example 3 were added to this tetraphenylphosphonium chloride and a reaction was carried out in the same manner as in Example 3 (second reaction), the conversion of diphenyl oxalate was 99.5. %, The selectivity of diphenyl carbonate was 99.0%.

Example 5 Tetraphenylphosphonium chloride was recovered in the same manner as in Example 3 except that 30 ml of deionized water and 30 ml of toluene were used instead of 50 ml of deionized water.
Tetraphenylphosphonium chloride 0.4391g
Was recovered (recovery rate: 95.2%). However, in this case, a liquid separation operation was performed instead of the above-mentioned suction filtration to treat the obtained aqueous phase. To this tetraphenylphosphonium chloride, the same amounts of diphenyl oxalate and chloroform as in Example 3 were added, and the reaction was carried out in the same manner as in Example 3 (Reaction 2
The second time), the conversion of diphenyl oxalate was 99.5% and the selectivity of diphenyl carbonate was 99.0%.

Example 6 The amount of diphenyl oxalate was 10.03 g (41.2).
9 mmol) and the amount of tetraphenylphosphonium chloride was changed to 0.3102 g (0.826 mmol: 2.0 mol% with respect to diphenyl oxalate), 0.090 g of hydrogen chloride gas was replaced with chloroform to 1 volume of nitrogen gas. % For the decarbonylation reaction (Reaction 1
The second time) was performed and the analysis was performed. As a result, the conversion of diphenyl oxalate was 93.7% and the selectivity of diphenyl carbonate was 99.0%.

Thereafter, the residue containing tetraphenylphosphonium chloride obtained by recovering diphenyl carbonate from the reaction solution of the decarbonylation reaction by the same procedure as in Example 1 was directly used as a catalyst four more times ( The reaction was performed 5 times in total. However, in the four reactions, the same amounts of diphenyl oxalate and hydrogen chloride as in the first reaction were added each time. As a result, in the second reaction, the conversion of diphenyl oxalate was 93.2% and the selectivity of diphenyl carbonate was 99.0%.
In the second round, the conversion of diphenyl oxalate was 93.4.
%, The selectivity of diphenyl carbonate is 99.0%,
In the 4th reaction, the conversion of diphenyl oxalate was 9
2.9%, diphenyl carbonate selectivity 99.0
%, In the fifth reaction, the conversion of diphenyl oxalate was 93.3% and the selectivity of diphenyl carbonate was 99.
It was 0%.

The reaction solution from the fifth reaction was distilled under reduced pressure in the same manner as in Example 1 to remove 90% by weight of the reaction solution, and diphenyl carbonate was recovered from the reaction solution. After cooling the distillation residue containing tetraphenylphosphonium chloride to room temperature, 50 ml of deionized water was added thereto and treated in the same manner as in Example 1 to obtain 0.308 g of tetraphenylphosphonium chloride (recovery rate: 99. .4%). To this tetraphenylphosphonium chloride, the same amounts of diphenyloxalate and hydrogen chloride as described above were added, and a reaction (sixth reaction) was carried out in the same manner as described above. The conversion of diphenyloxalate was 93.0%. The selectivity of diphenyl carbonate was 99.0%.

[0068]

[Table 4]

[0069]

INDUSTRIAL APPLICABILITY According to the present invention, an organic phosphonium salt obtained by recovering diaryl carbonate from a reaction solution in a method for producing a diaryl carbonate by decarbonylating a diaryl oxalate in the presence of an organic phosphonium salt is used. The organic phosphonium salt can be efficiently recovered from the contained residue. Further, the recovered organic phosphonium salt can be reused as a highly active and highly selective catalyst. In particular, a decarbonylation reaction of diaryl oxalate in the presence of an organic phosphonium salt and recovery of the diaryl carbonate from the reaction solution, which is obtained by recycling the residue containing the organic phosphonium salt as a catalyst, continuously uses the diaryl carbonate. In the case of the above production, the organic phosphonium salt can be efficiently recovered from the residue extracted from the reaction system, and the recovered organic phosphonium salt can be reused as a highly active and highly selective catalyst.

[Brief description of drawings]

1 is a flow sheet showing an embodiment of the present invention, in which 1 is a reactor, 2 is an evaporator, 3 is a distillation column, 4 is a recovery device, and 1 to 11 are conduits. .

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Keigo Nishidaira Keigo Nishidaira 10 1978, Obeshi, Ube City, Yamaguchi Prefecture 10 Ube Industries, Ltd. Ube Integrated Works (72) Inventor, Shuji Tanaka, 1978, Kobeshi, Ube, Yamaguchi Prefecture 10 Ube Industries, Ltd. Ube Integrated Works (72) Inventor Hirofumi Ii 10 1978, Kozugushi, Ube City, Yamaguchi Prefecture 10 Ube Industries Ltd. Ube Integrated Works (56) Reference JP-A-8-333307 (JP, JP, 333307) A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C07C 68/00 C07C 69/96

Claims (7)

(57) [Claims] 1. In the first step, the dearyl oxalate is subjected to a decarbonylation reaction in the presence of an organic phosphonium salt to produce a diaryl carbonate, and (2) the second step.
In the step, the diaryl carbonate is recovered from the reaction solution, and in the third step, (3) in the presence of the residue containing the organic phosphonium salt, a halogen compound is added to carry out a decarbonylation reaction of the diaryl oxalate. While producing carbonate, (4) in the fourth step,
The residue containing the organic phosphonium salt is extracted from the reaction system, and the organic phosphonium salt is recovered by water extraction from the residue. (5) In the fifth step, the recovered organic phosphonium salt is collected in the diaryl group of the third step. A process for producing a diaryl carbonate, which is characterized by being reused in a decarbonylation reaction of oxalate. 2. The method for producing a diaryl carbonate according to claim 1, wherein the organic phosphonium salt is a tetraarylphosphonium salt. 3. The method for producing a diaryl carbonate according to claim 1, wherein the organic phosphonium salt is a tetraarylphosphonium halide or a tetraarylphosphonium hydrogen dihalide. 4. The diaryl carbonate according to claim 1, wherein the halogen compound is an organic halogen compound having a structure in which a halogen atom is bonded to saturated carbon or a structure in which a halogen atom is bonded to carbonyl carbon. Manufacturing method. 5. The method for producing a diaryl carbonate according to claim 1, wherein the halogen compound is an inorganic halogen compound selected from a halogen compound of phosphorus, a halogen compound of sulfur, hydrogen halide and a simple substance of halogen. 6. The method for producing a diaryl carbonate according to claim 4 or 5, wherein the halogen compound is a chlorine compound. 7. (1) A decarbonylation reaction of diaryl oxalate in the presence of an organic phosphonium salt to produce a diaryl carbonate, (2) recovery of the diaryl carbonate from the reaction solution, and (3) an organic phosphonium salt. A method for recovering an organic phosphonium salt, which comprises extracting the contained residue and extracting the organic phosphonium salt from the residue with water.