JP2001288148A - Method for producing aromatic carbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recover and re-utilize platinum group metal or a platinum group compound catalyst in a process for producing an aromatic carbonate represented by the formula (I) R-O-CO-O-R (wherein R is selected from a substituted or unsubstituted 6-15C aryl) by reacting an aromatic hydroxy compound with carbon monoxide and oxygen in the presence of a catalyst composition composed of a platinum group metal or a platinum group compound, a redox agent and a quaternary ammonium salt or a phosphonium salt. SOLUTION: Selective crystallization of the aromatic carbonate is carried out by adding a solvent capable of compatibilizing with the aromatic hydroxy compound and having 7.0-10.0 solubility parameter δS to a reaction mixture solution consisting essentially of the aromatic carbonate obtained from the above reaction and the aromatic hydroxy compound and the resultant crystal is isolated and the solvent is removed from the residual solution containing the catalyst and then the catalyst is recovered and re-utilized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an aromatic carbonate. Specifically, carbon monoxide and oxygen are circulated through the aromatic hydroxy compound,
This is a method for producing an aromatic carbonate using a catalyst comprising (1) a platinum group metal or platinum group compound, (2) a redox agent, and (3) a quaternary ammonium salt. More specifically, the reaction mixture solution obtained by the above-described method is compatible with the aromatic hydroxy compound and has a solubility parameter δs of 7.0.
A solvent in the range of ~ 10.0 is added to selectively crystallize the aromatic carbonate, the crystals are isolated, the solvent is removed from the solution containing the remaining catalyst, and the catalyst is recovered and reused. This is a method for producing an aromatic carbonate.

[0002]

2. Description of the Related Art Aromatic polycarbonates are widely used as engineering plastics having excellent heat resistance and transparency. As a method for producing the aromatic polycarbonate, a method of polymerizing an aromatic dihydroxy compound and phosgene at an interface and a melt transesterification method of polymerizing an aromatic dihydroxy compound and an aromatic carbonate in a molten state are known. However, the former has a problem in that a large amount of highly toxic phosgene and environmentally problematic halogen-based solvents such as methylene chloride are used. In this regard, the latter can solve this problem, but depending on the purity of the aromatic carbonate used, problems such as a decrease in polymerization activity and coloring of the aromatic polycarbonate occur. As a method of avoiding these, a method of conducting a carbonylation reaction of an aromatic hydroxy compound with carbon monoxide and oxygen in the presence of a catalyst has been studied. Generally, a plurality of expensive catalysts are used in the carbonylation reaction, and their separation and recovery and recycle are important issues.

In US Pat. No. 5,981,788, a mixture of phenol, diphenyl carbonate, palladium salt, cobalt salt and quaternary ammonium salt is subjected to 1) extraction of a metal component with hydrochloric acid and an aqueous sodium chloride solution at least once. 2) removal of phenol by evaporation; 3)
It has been shown that by performing water extraction of a quaternary ammonium salt one or more times, it is possible to separate 48% of a palladium component, 90% or more of a cobalt component, and 60% or more of a quaternary ammonium salt. . However, this method has three disadvantages. For one thing, the costs associated with separation equipment and energy are inevitable. Second, diphenyl carbonate is exposed to heat, acid, and water several times during the process, and the amount obtained is reduced due to hydrolysis and the like. Third, the catalyst components, especially the quaternary ammonium salts, which are prone to thermal decomposition, degrade during the heat treatment in this step. As described above, the aromatic carbonate and the catalyst component can be separated by the conventional method, but it is hardly economical.

In Japanese Patent Application Laid-Open No. 6-172270, a crystalline adduct of diphenyl carbonate and phenol having a molar ratio of 1: 1 is produced from a reaction solution containing a catalyst by a suspension crystallization method and separated from the reaction solution. Teaching that. In this method, in order to obtain and separate a crystalline adduct in a high yield, the reaction solution is limited to a reaction solution containing diphenyl carbonate in a narrow concentration range of 50 to 70% by weight, and a crystallization mixture before recovery of the crystalline adduct. In order to lower the solid content level, an adduct crystallization device having two or more stages is required. Further, the crystalline adduct obtained by filtration contains a catalyst component, and in the subsequent purification (distillation or the like) of the crystalline adduct, the remaining catalyst component has an adverse effect such as decomposition of diphenyl carbonate. It has also been proposed to wash the crystalline adduct with a mixed solution of 9% water and 91% phenol prior to heating under reduced pressure to separate the phenol. In addition to dissolving the part, it increases the amount of water in the crystalline adduct, and hydrolysis occurs during distillation for the purpose of isolating diphenyl carbonate,
Reduces the yield of diphenyl carbonate. Also 50
When the diphenyl carbonate-containing reaction solution having a concentration of less than 10% by weight is treated by the above-described method, distillation for the purpose of concentrating the reaction solution must be performed. However, in addition to the drawbacks described above, distillation also causes catalyst degradation due to thermal loading.

[0005] As another technique utilizing suspension crystallization, there is another technique disclosed in Japanese Patent Application Laid-Open No. 10-45680. However, even in this method, since a considerable amount of phenol is mixed in the crystal, further purification (such as distillation) is inevitable to obtain high-purity diphenyl carbonate. As described above, in the conventional method, the product quality is reduced due to the low separation efficiency, the cost of the recovery apparatus is increased, and a large amount of separation energy is required.

[0006]

A catalyst used in a method for carbonylating an aromatic hydroxy compound with carbon monoxide and oxygen, that is, a platinum group metal or a platinum group compound, a redox agent, and a quaternary ammonium salt Is very expensive, and it is desired to recover and reuse it from the reaction mixture solution. Accordingly, an object of the present invention is to provide a method for producing an aromatic carbonate which can recover and reuse these catalysts by utilizing selective crystallization of the aromatic carbonate. Another object of the present invention is to provide a method capable of obtaining high-purity aromatic carbonate by a relatively simple operation, and greatly reducing the cost and energy of an apparatus for purification.

[0007]

An aromatic hydroxy compound, carbon monoxide and oxygen are reacted in the presence of a platinum group metal or compound, a redox agent, and a catalyst comprising a quaternary ammonium salt or a phosphonium salt, The following formula (I)

[0008]

## STR2 ## Aromatic carbonate represented by R--O--CO--O--R (I) wherein R is selected from substituted or unsubstituted C ₆ -C ₁₅ aryl. In the method of producing, from the reaction mixture solution containing the aromatic carbonate and the aromatic hydroxy compound obtained by the reaction as a main component, the catalyst was recovered and reused, and as a result, a specific solubility parameter was determined. It has been found that when the third component solvent is added to the reaction mixture solution, the aromatic carbonate is crystallized and isolated, and these catalyst components can be advantageously recovered and reused from the remaining solution.

That is, the present invention provides an aromatic hydroxy compound,
Carbon monoxide and oxygen as platinum group metals or platinum group compounds,
The reaction is carried out in the presence of a redox agent and a catalyst comprising a quaternary ammonium salt or a phosphonium salt, to give the following formula (I)

[0010]

## STR3 ## R-O-CO-O- R ··· (I) ( wherein, R is selected from aryl of C ₆ -C ₁₅ substituted or unsubstituted.) Aromatic carbonate represented by In the reaction mixture obtained by the reaction, which contains the aromatic carbonate and the aromatic hydroxy compound as main components, is compatible with the aromatic hydroxy compound, and has a solubility parameter δs of 7.0 to 10. A solvent in the range of 0 is added to selectively crystallize the aromatic carbonate, the crystals are isolated, the solvent is removed from the remaining solution, and the catalyst is recovered and reused. This is a method for producing an aromatic carbonate.

The solubility parameter δ in the present invention
KLHoy's concept of molar traction (J.Paint Technol., 4
2, 76) (1970) and is calculated from the following equation (III).

[0012]

Δ = dΣG / M (III) (where d is density, G is molar traction constant, and M means molecular weight)

[0013]

DETAILED DESCRIPTION OF THE INVENTION The aromatic hydroxy compound used in the present invention includes, for example, phenol, cresol, xylenol, ethylphenol, propylphenol, methoxyphenol, ethoxyphenol, and the like.
Substituted phenols such as chlorophenol, bromophenol and salicylic acid, and isomers thereof, substituted naphthols such as naphthol, methylnaphthol and chloronaphthol and their isomers, bisphenols such as bisphenol A, and the like, Among them, phenol is particularly preferred.

The platinum group metals used in the present invention include:
For example, palladium, platinum, ruthenium, rhodium, osmium, and iridium can be mentioned, and among them, palladium is particularly preferable. The state of such a platinum group metal is
An active metal state, palladium nitrate, inorganic acid salts such as palladium chloride, organic acid salts such as palladium acetate, complex salts such as palladium acetylacetonate, oxides or hydroxides, or carbon monoxide, olefins, It is in the form of a complex compound containing an amine, phosphine or halogen, and these platinum group metal compounds are suitable supports, for example, activated carbon, silica gel, alumina, metal oxides such as titanium oxide and zirconium oxide, and metal complexes such as perovskite. It may be in a state of being supported on an oxide or silicon carbide or the like, and may be in a state in which most of the support and its support have been separated and removed in advance. Among them, palladium acetylacetonate is preferable.

The palladium catalyst has a molar ratio of palladium atom to aromatic hydroxy compound of 1 to 1 × 10 ^-5.
Although it can be used, a range of 1 × 10 ⁻² to 10 ⁻⁴ is desirable.

The aromatic carbonate production reaction of the present invention is more preferably carried out in the presence of a redox agent. Such redox agents include IIIA, IVA, VA, and
VIA, IB, IIB, VIB, VIIB, iron group (VIII) and rare earth metal (IIIB) compounds. Compounds of these metals can be used in various oxidation states, for example, halides, oxides, hydroxides, carbonates, organic carboxylate salts, diketone salts, oxalate salts, complex salts such as salicylates and the like. In addition, it can be used as a complex in which carbon monoxide, olefins, amines, phosphines and the like are coordinated. Among these metal compounds having redox ability, preferred are manganese, cobalt, copper and compounds of rare earth metals such as lanthanum and cerium and compounds of lead, and particularly preferred are manganese, cobalt, copper and cerium metal. And lead compounds. The amount of these redox agents to be used is not particularly limited, but is preferably in the range of 1 × 10 ^-1 to 1 × 10 ³ in terms of molar ratio with respect to the platinum group metal compound, and particularly preferably 1 × 10 ^-1 to 1 × 10 ^-1 . It is preferably in the range of 1 × 10 ² .

The quaternary ammonium salts include tetrabutylammonium bromide, tetrabutylammonium chloride, tetraphenylphosphonium chloride,
Tetraphenylphosphonium bromide and the like can be mentioned, and tetrabutylammonium bromide is preferably selected. The amount of the quaternary ammonium salts, from 1 to 10 ² in the molar ratio of platinum group metal compound, preferably 10 to 50.

In carrying out the reaction, either a closed system or a gas flow system may be used. The pressure in the reaction vessel is set to a total pressure of carbon monoxide and oxygen of 1 to 10 kg / cm ²
And preferably 5 to 9 kg / cm ² . Further, the ratio of the oxygen partial pressure to the total pressure is not particularly limited as long as it is outside the range of explosion of carbon monoxide. Further, when the flow system is adopted, the gas flow rate is 0.3 to 2.0 L per minute for 1 mol of the aromatic hydroxy compound for carbon monoxide, and 0.01 to 0.1 L for 1 mol for oxygen. It is preferably in the range of 0.75 to 1.2 L / min of carbon monoxide and 0.1 to 0.1 L of oxygen.
03-0.075 L per minute.

The reaction temperature is not limited, but is preferably in the range of 60 ° C to 120 ° C, more preferably 80 ° C to 100 ° C.

In the presence of the catalyst, an aromatic hydroxy compound is reacted with carbon monoxide and molecular oxygen to produce an aromatic carbonate, and the obtained aromatic carbonate and the aromatic hydroxy compound are the main components. The reaction mixture is introduced into a suitable crystallizer. The concentration of the aromatic carbonate contained in the obtained reaction mixture solution is 5 to 9
It is 5% by weight, preferably 7-70% by weight.

The crystallization apparatus used here is, for example, a stirrer crystallization apparatus as described in JP-A-10-45680, or a bundle tube as described in JP-A-10-59904. It is a crystallization apparatus, but is not limited to these.

The solvent added to the reaction mixture solution is compatible with the aromatic hydroxy compound and has a solubility parameter δs
Is in the range of 7.0 to 10.0. Examples of the solvent satisfying the above conditions include aliphatic ketones, C _{1 to} C ₃ alcohols, C _{3 to} C ₆ aliphatic ethers, C _{5 to} C ₈ cycloaliphatic hydrocarbons and C it can be selected at least one selected from the group consisting of ₆ -C ₈ aromatic hydrocarbons.

Examples of the solvent include methanol, ethanol, acetone, diethyl ether, tetrahydrofuran, cyclohexane, toluene, and xylene, and methanol, acetone, and toluene are preferred. In the present invention, at least one kind is selected from such solvents.

The melting point of the solvent itself is at least the melting point of phenol, preferably 41 ° C. or less, more preferably 15 ° C. or less.

With respect to the added amount Ws (g) of the solvent, the following formula (II)

The quantity satisfies δd− [δsWs / (Ws + Wa) + δaWa / (Ws + Wa)] ≧ 0.6 (II).

The solvent dissolves phenol effectively and precipitates diphenyl carbonate, so that it is simpler and lower in energy than the conventional method, and is a platinum group metal or a platinum group compound, a redox agent, and a quaternary ammonium salt. And unreacted phenol can be recovered. In addition, when the uniformity of the reaction mixture solution is maintained by the addition of the solvent, it is not necessary to perform crystallization particularly under stirring, and the present invention can be sufficiently achieved even when the reaction mixture solution is left still.
The introduced reaction mixture solution was added after the addition of the solvent.
From a temperature range of -40 ° C, preferably 60-40 ° C, to 3
It is cooled to a temperature range of 0 to -30C, preferably 30 to 0C. Crystals are formed as the temperature drops, but due to the effect of the added solvent, the growing crystals are rich in diphenyl carbonate.

The diphenyl carbonate crystals are isolated using a centrifuge or the like, and the solvent is removed from the remaining solution. When removing the solvent, for example, the catalyst can be easily removed by an operation such as distillation under mild conditions to recover the catalyst, and the catalyst component can be recycled to a reaction tank for producing an aromatic carbonate. it can.

[0028]

The present invention will be described in detail with reference to the following examples.
The present invention is not limited to these.

Example 1 In a stainless steel autoclave having a volume of 500 ml, 200 mg of palladium acetylacetonate, 250.0 g of phenol, and 0.5% of lead oxide were placed.
g, manganese acetylacetonate 0.35 g, and tetrabutylammonium bromide 5.0 g. The inside of the container was maintained at 80 ° C., the atmosphere was replaced with nitrogen and carbon monoxide in that order, and the inside of the container was further pressurized with carbon monoxide to 8.0 kg / cm ² . Thereafter, carbon monoxide 2.5 L / min, oxygen 0.1
The reaction was started by flowing at the same time at a flow rate of 25 L / min.
As a result of continuing the reaction for 3 hours, 17.9% of diphenyl carbonate was formed on a phenol basis. 20 g of the reaction mixture solution thus obtained was collected, and methanol (δ
s = 9.24) Add 10 g, introduce into an apparatus suitable for crystallization, and cool from 45 ° C. to 20 ° C. When the crystallization was completed, the solution containing the crystals and the catalyst was separated by filtration. 0.9 mg (0.2% of theory) of tetrabutylammonium bromide was mixed into the obtained crystal.
The amount of metal components such as n and Pb is extremely small.
9.0% of the catalyst and 97.2% of phenol could be recovered.

Example 2 The amount of methanol used was 5 g
The procedure was performed in the same manner as in Example 1 except for the above. Incorporation of tetrabutylammonium bromide into the obtained crystal was as follows.
9 mg (0.5% of the theoretical amount), the amount of metal components such as Mn and Pb is extremely small, and 98.2% or more of the catalyst and
98.0% of phenol could be recovered.

[0031]

According to the present invention, an aromatic hydroxy compound, carbon monoxide, and oxygen are used, and (1) a platinum group metal or a platinum group compound, (2) a redox agent and (3) a quaternary ammonium. The reaction mixture obtained by coexisting the salt is compatible with the aromatic hydroxy compound and has a solubility parameter δ.
By adding a solvent in which s is in the range of 7.0 to 10.0, the aromatic carbonate can be selectively crystallized from the reaction mixture solution. Here, the solvent is removed by a simple operation such as distillation from a solution containing a catalyst composed of the aromatic hydroxy compound, the catalyst, and the solvent, and a mixed solution of the aromatic hydroxy compound and the catalyst is formed as follows. It can be reused for different reactions. Therefore, the equipment cost for recovering the catalyst and the energy required for separation and recovery can be significantly reduced. The inventors isolated diphenyl carbonate crystals using this method and succeeded in recovering 99% or more of the catalyst component and 98% or more of phenol.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tsuyoshi Muraoka 2-1 Hinode-cho, Iwakuni-shi, Yamaguchi Pref. Teijin Limited Iwakuni Research Center (72) Inventor Eiyoshi Zenzato 2-1 Hinode-cho, Iwakuni-shi, Yamaguchi Teijin Iwakuni Research Center F term (reference) 4H006 AA02 AC13 AD15 BA05 BA08 BA11 BA16 BA20 BA25 BA51 BA53 BB11 BB14 BB15 BB16 BC11 BD36 BD52 BJ50 4H039 CA66 CF30

Claims (10)

[Claims] 1. An aromatic hydroxy compound, carbon monoxide and oxygen are reacted in the presence of a platinum group metal or a platinum group compound, a redox agent, and a catalyst comprising a quaternary ammonium salt or a phosphonium salt to obtain a compound represented by the following formula (I) (1) Aromatic represented by R—O—CO—O—R (I) wherein R is selected from substituted or unsubstituted C _{6 to} C ₁₅ aryl. In the method for producing a carbonate, a reaction mixture solution containing an aromatic carbonate and an aromatic hydroxy compound as main components obtained by the reaction is compatible with the aromatic hydroxy compound and has a solubility parameter δs of 7.0 to 10. 2.0, and selectively crystallize the aromatic carbonate by adding a solvent in the range of 0.02 to 2.0 g., Isolating the crystals, removing the solvent from the solution containing the remaining catalyst, and recovering and reusing the catalyst. Features Preparation of aromatic carbonate to be. 2. The method according to claim 1, wherein the platinum group metal or platinum group compound is palladium or a compound of palladium. 3. The method according to claim 2, wherein the redox agent is manganese, cobalt,
3. The method according to claim 1, comprising one or more selected from the group consisting of salts or compounds of copper, cerium or lead. 4. The method according to claim 1, wherein the quaternary ammonium salt is a tetraalkyl ammonium halide. 5. The method according to claim 1, wherein the reaction is carried out under a gas flow for maintaining a constant partial pressure of carbon monoxide and oxygen. 6. The addition amount Ws of the solvent is represented by the following formula (II): δd− [δsWs / (Ws + Wa) + δaWa / (Ws + Wa)] ≧ 0.6 (II) Is the solubility parameter, W is the weight (g)
The subscript a represents an aromatic hydroxy compound, d represents an aromatic carbonate, and s represents the solvent). 7. The method according to claim 1, wherein the concentration of the aromatic carbonate contained in the reaction mixture solution is in the range of 5 to 95% by weight. 8. The method according to claim 1, wherein the concentration of the aromatic carbonate contained in the reaction mixture solution is in the range of 7 to 70% by weight. 9. The method according to claim 1, wherein the solvent has a melting point of 15 ° C. or lower. 10. The solvent is an aliphatic ketone, a C ₁ -C ₃ alcohol, a C ₃ -C ₆ aliphatic ether, a C ₅ -C _8.
The method of any of claims 1-9 cycloaliphatic hydrocarbons, and is at least one selected from the group consisting of aromatic hydrocarbons C ₆ -C _8.