JPH0240047B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention produces an aromatic compound by iodinating an aromatic compound having an electron donating group by electrolytic oxidation reaction to obtain an iodinated aromatic compound, and then reacting it with a nucleophilic reagent. It's about how to do it.
In particular, from aniline (hereinafter abbreviated as AN) to p-
The present invention relates to a method for obtaining iodoaniline (hereinafter abbreviated as PIA) and then producing p-phenylenediamine (hereinafter abbreviated as PPD). PPD is used for dyes, pigments, pharmaceuticals, aramid fibers,
It has useful uses as a synthetic intermediate such as monomers for polyimide resins. (Prior art) As a method for producing an aromatic compound by iodinating an aromatic compound having an electron-donating group by electrolytic oxidation reaction and then reacting it with a nucleophilic reagent, AN
US Pat. No. 3,975,439 is known in which PIA is obtained by electrolytic oxidation reaction of iodination of PIA, which is then reacted with ammonia. In this method, PIA is obtained by an electrolytic oxidation reaction of AN using the diaphragm method, and after ammonia and PIA are reacted, the by-produced ammonium iodide and sodium hydroxide are reacted to recover ammonia and sodium iodide. The sodium iodide produced is returned to the electrolytic system to produce PPD. (Problems to be Solved by the Invention) When an electrolytic reaction is carried out according to the prior art, when a diaphragm is used, hydrogen iodide is produced along with the electrolytic reaction, and the material becomes acidic quite rapidly. Initially, the anolyte is a two-layer system of oil and water, but as electrolysis progresses, it eventually becomes a homogeneous system. Although there is no description of such a phenomenon, there is a description of adding an aqueous sodium hydroxide solution to maintain the pH in the range of 5 to 8 as a means to ensure separation of the anolyte in the decanter. However, as shown in the comparative example, when an electrolytic reaction is carried out while adding an aqueous sodium hydroxide solution,
In the first place, it was found that not only was it extremely difficult to maintain the pH within the range of 5 to 8, but the voltage also fluctuated considerably, making it extremely difficult to perform the electrolytic reaction stably. Furthermore, by-products such as azobenzene and 4-aminodiphenylamine were also produced, albeit in small amounts. It was also observed that the oil layer was moving through the diaphragm (in this case, a perfluorocarbon type cation exchange membrane was used). On the other hand, in the case of non-diaphragm electrolysis, as shown in the comparative example, the current efficiency was considerably reduced and a large amount of by-products azobenzene and 4-aminodiphenylamine were produced. (Means and effects for solving the problem) The present inventors have conducted extensive research to overcome the drawbacks of the conventional methods as described above and to develop a technology that can withstand industrialization, and as a result, ammonium phosphate discovered that by adding sodium phosphate or potassium phosphate to the electrolyte, it is possible to perform PIA with high current efficiency, suppress the production of by-products, and stably perform the electrolytic reaction. Furthermore, it has been found that even greater effects can be achieved by limiting the pH of the aqueous electrolyte phase to a specific range. This idea is similar to PPD in conventional technology.
It can be applied not only to the production of , but also to aromatic compounds having specific electron-donating groups. In addition, the iodine produced by the electrolytic oxidation reaction can be taken out of the electrolytic system and reacted with an aromatic compound that has electron donating properties, so the present invention can also be applied to aromatic compounds that are unstable within the electrolytic system. can. The present invention is based on the above findings, and uses water-soluble electrolyte iodide in an electrolytic solution whose pH is maintained at 5.5 to 10.0 with ammonium phosphate, sodium phosphate, or potassium phosphate. Iodine obtained by electrolytic oxidation is converted into an amino group, N
-React with an aromatic compound having an alkylamino group, N,N'-dialkylamino group, hydroxy group or alkoxy group, and ammonia, aminophenol, cyan ion or hydroxy ion is nucleophilic to the resulting iodinated aromatic compound. This is a method for producing an aromatic compound, characterized in that the reaction is carried out as a reagent. In the present invention, ammonium phosphate, sodium phosphate, or potassium phosphate is added to the electrolytic solution, which allows the electrolytic reaction to be carried out extremely stably. That is, the pH change of the electrolyte aqueous phase is extremely mild, and the pH can be easily adjusted. Furthermore, since the degree of dissociation of aromatic monoamines and iodinated aromatic amino compounds is small, they are less likely to be ionized and migrate to the cathode side through the diaphragm, or to cause side reactions. Further, there is less change in voltage, and the voltage is also lower. Among the above ammonium phosphate, sodium phosphate and potassium phosphate, sodium phosphate is industrially preferred. The phosphate concentration in the aqueous layer is preferably 1 to 20% by weight, and if it exceeds 20% by weight, the viscosity of the aqueous layer increases. The aromatic compound having an amino group, N-alkylamino group, N,N'-dialkylamino group, hydroxy group or alkoxy group used in the present invention is:
It is preferable that the substituent constant σp-1 of the fitting is -0.25 or less. Aromatic compounds with electron donating groups larger than -0.25 have extremely low current efficiency or do not react. The aromatic compounds mentioned above include, in particular, aniline, N-methylaniline, N,N-dimethylaniline, o-toluidine, m-toluidine, N-methyl-o-toluidine, N,N-dimethyl-o-toluidine, N - Aromatic amino compounds such as methyl-m-toluidine and N,N-dimethyl-m-toluidine, phenol, anisole,
Phenol derivatives such as o-cresol, m-cresol, 2,3-xylenol, 2,4-xylenol are suitable. In the present invention, it has also been revealed that the pH of the aqueous layer of the electrolytic solution has an extremely large effect on the electrolytic reaction. As is clear from the Examples and Comparative Examples, it has been revealed that high current efficiency can be obtained only in a specific pH range, and that almost no by-products are generated. That is, for aromatic amino compounds, the PH range of the aqueous layer is 5.5~
A range of 6.9 is preferred. When the pH is alkaline than 6.9, the current efficiency decreases particularly significantly, and the formation of azobenzene type and 4-aminodiphenylamine type by-products increases considerably. This phenomenon appears prominently in the case of non-diaphragm electrolysis because the aqueous phase becomes alkaline. When the pH is lower than 5.5,
More salts of aromatic amino compounds and iodinated aromatic amino compounds are produced, and in the case of diaphragm electrolysis, the amount that passes through the membrane and moves to the cathode side increases.
Moreover, it becomes difficult to carry out the electrolytic reaction normally. On the other hand, in the case of phenol derivatives, the pH of the aqueous layer is
From the viewpoint of yield, it is preferable to maintain it within the range of 6.5 to 10.0. In the present invention, these aromatic compounds having an electron-donating group can be supplied into the reaction system at any stage before the electrolytic oxidation reaction, during the electrolytic oxidation reaction, or after the electrolytic oxidation reaction. . Furthermore, a supply method combining any of these methods may be used. In either case, an iodinated aromatic compound can be obtained. Therefore, in the present invention, it is possible to freely select the timing of supplying the aromatic compound having an electron donating group into the reaction system.
In any case, it is preferable to maintain the pH of the aqueous layer in the reaction solution within the specified range. In the case of aromatic amino compounds, it is also possible to electrolytically oxidize iodide to generate iodine and then supply it to the reaction system. In this case, it is possible to easily increase the reaction rate of aromatic amino compounds. be. In the present invention, when handling a phenol derivative, it is suitable to supply the phenol derivative into the reaction system after the iodine generating electrolytic reaction. If a phenol derivative is present in the electrolytic oxidation reaction system, it will be oxidized and a large amount of by-products will be produced. In the present invention, examples of iodides that are soluble in water and serve as electrolytes include ammonium iodide, alkali metal iodides, and quaternary ammonium iodide salts, preferably ammonium iodide and iodide. Sodium and potassium iodide are used. Industrially, sodium iodide is particularly preferred. Preferably, the cation is the same as the cation of the phosphate described above. The electrolytic reaction of iodide can be carried out without any problem by either a diaphragm method or a diaphragmless method. In the case of the diaphragm method, hydrogen iodide is produced at the anode and the corresponding hydroxide is produced at the cathode. If hydroxide is required, the diaphragm method is selected. On the other hand, in the case of the non-diaphragm method, there is a high risk that the aqueous layer becomes alkaline due to hydroxide generated at the cathode and the current efficiency decreases; however, according to the present invention, in Example 3 and Comparative Example 3, As is clear, PH changes are small and high current efficiency can be stably obtained. This method does not require a diaphragm, simplifies the structure of the container, and allows the electrode spacing to be narrowed, thereby improving the power consumption rate. Anode materials include platinum, ruthenium, rhodium, and iridium alone or plated with titanium or tantalum, alloys and alloy platings, and oxidation of platinum, ruthenium, rhodium, and iridium with valve metals (titanium, tantalum, etc.). Examples include metal alloys, carbon, etc. The cathode material is preferably one with a low hydrogen overvoltage, but is not particularly limited, and examples include iron, nickel, stainless steel, and titanium. When using a diaphragm, a cation exchange membrane, an anion exchange membrane, etc. are used as necessary. The diaphragm method will be described below. Since the description is generally applicable to the non-diaphragm method, only examples are shown. The electrolytic cell may be one commonly used in organic electrolytic reactions, as long as it is capable of passing an electrolytic solution between the two electrodes. For example, in an electrolytic cell, a cathode plate and an anode plate are opposed in parallel, and a polyethylene plate, a diaphragm, and a polyethylene plate are placed in this order so as to form a cathode chamber and an anode chamber between the two electrodes. . An opening is provided in the center of each of these polyethylene plates to allow the electrolyte to pass therethrough. The current-carrying area of the electrode is determined by the size of the opening, and the distance between the electrode and the diaphragm is determined by the thickness of the polyethylene plate. The anolyte and catholyte enter the anode and cathode chambers from each tank through the supply ports provided in the electrolytic cell, and while passing through the chambers, a portion reacts and exits from the outlet, and is transferred to the anolyte tank. , return to the catholyte tank,
circulate between the tank and the chamber. The current density is preferably 1 to 30A/ ^dm2 , and 30A/dm2.
Current densities higher than dm ² result in significantly higher voltages, and current densities lower than 1 A/dm ² result in poor productivity. The electrolysis temperature is preferably 20 to 80°C. If the temperature is lower than 20℃, the voltage will increase and the power consumption will deteriorate.
If the temperature is higher than 80℃, it cannot be carried out due to the material of the battery case. The flow rate of the electrolytic solution in the electrolytic cell is preferably 0.1 to 4 m/sec. A flow rate lower than 0.1 m/s will reduce the current efficiency, and a flow rate higher than 4 m/s will cause a significant pressure loss within the electrolytic cell. The distance between the electrode and the diaphragm is usually preferably 0.5 to 3 mm. The pH of the aqueous phase can be adjusted, if necessary, by adding a corresponding hydroxide, hydrogen iodide, phosphoric acid, or the like. When iodide is electrolytically oxidized to produce iodine and then reacted with an aromatic amino compound, the produced iodine is continuously or intermittently added to the aromatic amino compound while maintaining the pH of the aqueous layer at 5.5 to 6.9. It is preferable to add and react. In the present invention, the iodinated aromatic compound obtained by electrolytic reaction is then reacted with a nucleophile such as ammonia, aminophenol, cyan ion, or hydroxy ion to produce the corresponding aromatic compound. Below, we will discuss the details of producing a corresponding aromatic amino compound by aminating an iodinated aromatic compound with ammonia, and an example where the iodinated aromatic compound is PIA and the aromatic amino compound is PPD. . The amination reaction is carried out by adding a catalyst and ammonia to an oil layer containing PIA generated by an electrolytic reaction.
The oil layer obtained by the electrolytic reaction contains the raw material AN, the product PIA, and water equivalent to the solubility, and the amination reaction is basically not a non-aqueous system.
It is carried out in the presence of water. Ammonia is added in a molar amount 10 to 50 times the amount of the iodinated aromatic compound.
It is preferable to add 20 to 30 times the molar amount. There is no problem if the water concentration in ammonia is less than 50% by weight, and preferably less than 20% by weight since by-products are reduced. The amination reaction temperature is also related to the type and amount of the catalyst used, but the reaction can proceed at room temperature or higher, but from the viewpoint of reaction rate, it is preferably 50°C or higher.
From the viewpoint of reaction pressure, the temperature is preferably 150°C or lower. Further, in the amination reaction, it is preferable to allow the iodinated aromatic compound to react completely, and for this purpose, it is preferable to conduct the reaction at a temperature of 70° C. or higher. The catalyst used in the amination reaction is preferably a cuprous compound. More preferred are cuprous hydroxide, cuprous oxide, etc. in addition to cuprous iodide, which have the same anion. The reaction rate of cupric compounds is slow.
Catalyst for iodinated aromatic amino compounds
It is used in an amount of 0.5 to 50 mol%, preferably 2 to 20 mol% from the viewpoint of reaction rate. The reaction solution after the amination reaction is a solution containing AN, the product PPD, ammonium iodide, a catalyst, excess ammonia, and water. In order to separate the product PPD from this reaction solution, first the excess ammonia is collected and separated, then the catalyst is collected and separated, then ammonium iodide is collected and separated, and then the aromatic diamine is collected and separated. It is necessary. In order to recover the copper catalyst from the amination reaction solution, after removing excess ammonia, ammonium ions (present as ammonium iodide) are removed.
When producing iodinated aromatic compounds using diaphragm electrolysis, the by-product alkali hydroxide is added and removed, and when produced using non-diaphragm electrolysis, water is added to separate the two layers. However, it is preferable to carry out the removal by water extraction or the like, and then make the ether and the alkali hydroxide exist simultaneously. Unless ammonia is removed, the copper catalyst cannot be completely recovered.
Unless alkali hydroxide and ethers are added at the same time, the copper catalyst cannot be completely recovered. However, AN
When amination is carried out using PIA containing almost no ethers, it is possible to recover the copper catalyst without adding ethers. The ethers are preferably aliphatic ethers having 6 to 8 carbon atoms. More preferred are dibutyl ether and diisopropyl ether, which are industrially easily available. If the number of carbon atoms is less than 5, separation of the copper catalyst will be insufficient, and if the number of carbon atoms is more than 9, the boiling point will be high and separation by distillation will be difficult. The amount of ether added is 0.5 to 5 of AN contained in the amination reaction solution.
Double doses are preferred. If the amount is less than 0.5 times, the separation of the copper catalyst will be insufficient, and if the amount is more than 5 times, the circulation of ethers will increase. The alkali hydroxide is preferably sodium hydroxide or potassium hydroxide. Particularly in the case of the diaphragm method, alkali hydroxide generated at the cathode can be used. Although it is industrially preferable that ammonium iodide produced as a by-product in the amination reaction is recovered as an aqueous solution and circulated into the electrolytic solution, it can also be mixed with an iodide other than the recovered iodide and circulated. Ammonium iodide is recycled after being converted into alkali iodide, if necessary. As mentioned above, when producing an iodinated aromatic compound by the diaphragm electrolysis method, it is preferable to convert it to an alkali iodide. Recovery and separation of ammonium iodide can be carried out, for example, by adding an aqueous alkali hydroxide solution when separating the catalyst.
Either alkali iodide is extracted and separated from the oil layer as an aqueous alkali hydroxide solution, or water is added after the catalyst is separated, and ammonium iodide is extracted and separated from the oil layer as an aqueous solution. On the other hand, PPD is mainly present in the oil layer containing the starting material AN, but is also distributed in a considerable amount in the aqueous layer containing alkali iodide or ammonium iodide, and this aqueous layer can be used, for example, in the aqueous layer containing AN. Extraction is preferred. PPD is separated from the liquid containing PPD and AN obtained in this way by distillation. The aqueous solution of alkali iodide or ammonium iodide (collectively abbreviated as iodide) recovered as described above is circulated into the electrolytic solution after being mixed alone or with other iodides. In this circulating aqueous solution, even if the aromatic diamine product is separated by the extraction process described above, it is generally contaminated in some amount because it has a high solubility in water. . Another feature of the invention is regulating the amount of PPD in the aqueous iodide solution circulating in the electrolyte. As shown in Examples 4, 5, 6, and 7, and Comparative Example 4, it has been found that even a small amount of PPD mixed into the electrolytic solution causes a significant deterioration of the electrolytic reaction. That is, PPD in the electrolyte
As the concentration of anode increases, the current efficiency decreases significantly, and moreover, a polymeric substance adheres to the anode surface, causing a phenomenon in which the voltage increases. In order to prevent such a phenomenon, it is necessary to thoroughly remove PPD from the iodide aqueous solution circulating in the electrolyte. That is, in the electrolyte
It is preferable to remove PPD from the circulating iodide aqueous solution to a concentration that maintains the concentration of PPD at 0.5% by weight or less. More preferably, in the electrolyte
The goal is to keep the concentration of PPD below 0.1% by weight. By adding ideas based on the above knowledge, it became possible to assemble the entire process including the collection and circulation of iodide to the electrolytic system. Next, a method for producing diaminodiphenyl ether (hereinafter abbreviated as DADPE) by a reaction between an iodinated aromatic compound and an aminophenol, for example, a coupling reaction between PIA and aminophenol, will be described in detail. As the solvent, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, aniline, tetrahydrofuran, benzene, toluene, etc. are used, and polar solvents are particularly preferred. These solvents may be used alone or in combination of two or more. As catalyst copper or most copper compounds are used, but preferred are cuprous iodide, cuprous chloride, cuprous oxide, cuprous bromide, cuprous cyanide.
These include copper, copper sulfate, cupric chloride, cupric hydroxide, cupric oxide, cupric bromide, cupric phosphate, copper nitrate, copper carbonate, copper acetate, and the like. These compounds may be used alone or in combination of two or more. There is no particular restriction on the amount used, but it is preferably in the range of 0.1 mol % to 50 mol % based on the reactant PIA. As the alkali, sodium hydroxide, potassium hydroxide, alcoholate, sodium hydride, sodium amide, sodium, potassium, etc. are used, but when considering the recovery of alkali iodide which is a by-product after the coupling reaction, sodium hydroxide or Preference is given to using potassium hydroxide. That is, the recovered alkali iodide is recycled to the electrolytic process for PIA production after an appropriate purification treatment. At this time, the product DADPE, like the aminated product PPD, significantly worsens the electrolytic reaction, so the concentration in the electrolyte should be kept at 0.5% by weight or less, preferably 0.1% by weight or less. is necessary. In the coupling reaction, PIA, aminophenol, alkali, catalyst, and solvent may be placed in a reactor all at once and reacted. Alternatively, the aminophenol alcoholate may be generated only with aminophenol, alkali, and solvent, and then You may add PIA and a catalyst to react. Reaction takes place from room temperature to 200℃
The reaction temperature can be selected depending on the relationship with the reaction time. Further, the reaction is preferably carried out under a nitrogen or argon stream. Next, the reaction between an iodinated aromatic compound and a cyanide ion is carried out using p-aminobenzonitrile (hereinafter referred to as
The method for manufacturing PABN (abbreviated as PABN) will be described in detail. Polar solvents are usually used as solvents, and generally include methanol, ethanol, ethylene glycol, ethylene glycol monomethyl ether,
Acetonitrile, aniline, dimethylformamide, dimethylacetamide, dimethylsulfoxide, etc. are used, but polar aprotic solvents are preferred. These solvents may be used alone or in combination of two or more. As the catalyst, cuprous cyanide is most preferably used, but other examples include cuprous iodide, copper sulfate,
Cuprous oxide, cuprous bromide, cuprous chloride, cuprous oxide
Copper, cupric bromide, cupric chloride, copper acetate, copper nitrate, and the like may be used alone or in combination of two or more. There is no particular restriction on the amount used, but it is preferably in the range of 0.1 to 50 mol% based on PIA, which is a reactant. As the cyano compound, sodium cyanide and potassium cyanide are generally used, but hydrogen cyanide can also be used. The reaction is carried out by placing PIA, a cyano compound, a catalyst, and a solvent in a reactor at a temperature ranging from 50°C to 250°C, but the reaction temperature can be selected depending on the relationship with the reaction time. Further, the reaction is preferably carried out in a nitrogen atmosphere. The iodide recovered by the reaction is recycled and reused in the electrolytic process for PIA production after being subjected to appropriate purification treatment. At this time, the product
PABN, like PPD during amination reaction,
Since this will worsen the electrolytic reaction, it is necessary to maintain the concentration in the electrolytic solution at 0.5% by weight or less. Next, a method for producing p-aminophenol by the reaction between an iodinated aromatic compound and a hydroxyl ion, and, as an example, a reaction between PIA and a hydroxyl compound will be described in detail. As the catalyst, cuprous oxide is most preferably used, but other examples include cuprous iodide, cuprous sulfate, cuprous oxide, cuprous bromide, cuprous chloride, cupric oxide,
Cupric bromide, cupric chloride, copper acetate, copper nitrate, and the like may be used alone or in combination of two or more. There are no particular restrictions on the amount used, but it is a reactant.
A range of 0.1 to 50 mol% based on PIA is preferred. As the hydroxy compound, sodium hydroxide and potassium hydroxide are preferably used from the viewpoint of recovery of alkali iodide produced as a by-product after the reaction. That is, the recovered alkali iodide is recycled and reused in the electrolysis process for PIA production after an appropriate purification treatment. At this time, the concentration of p-aminophenol in the electrolytic solution is preferably 0.5% by weight or less, as mixing of the product p-aminophenol into the electrolytic system will significantly worsen the electrolytic reaction.
It is necessary to keep it below 0.1% by weight. In addition to the reaction between the iodinated aromatic compound and the nucleophilic reagent detailed above, an aromatic compound can be produced by a similar reaction as appropriate. Next, a hypothetical example of a method for manufacturing PPD from AN, which is an example of the present invention, will be explained with reference to a flow sheet shown in the drawings. Reference numeral 2 denotes an anolyte tank, into which the raw material AN is supplied from the conduit 1, and the recovered sodium iodide concentrated in the distillation column 24 and the AN recovered in the distillation column 19 are circulated. The anolyte is circulated to an electrolytic cell 3 partitioned by a cation exchange resin membrane, during which an electrolytic iodination reaction is carried out. On the other hand, 4 is a catholyte tank, and the catholyte is, for example, an aqueous sodium hydroxide solution, and is circulated to the electrolytic cell 3. A portion of the anolyte is sent to a decanter 5 to separate the aqueous layer, an aqueous solution of sodium phosphate and sodium iodide, and the organic layer, an AN solution of PIA. The water layer is circulated to the anolyte tank 2.
The organic layer is sent via conduit 6 to amination reactor 7. The amination reaction liquid is supplied with ammonia from a conduit 8, compressed together with the ammonia recovered in an ammonia water distillation column 10, and furthermore, cuprous iodide catalyst separated and recovered by a filter 13 is supplied to a conduit 9. It is supplied and prepared through When the reaction is completed, excess ammonia is recovered through the ammonia water distillation column 10, and an aqueous sodium hydroxide solution as a catholyte is added in excess of the equivalent amount through the conduit 11 to iodize the ammonium iodide produced as a by-product in the amination reaction. At the same time as converting to sodium,
The generated ammonia is recovered through an ammonia water distillation column 10. At this time, water is separated from the evaporated ammonia water in an ammonia water distillation column 10. The reaction solution from which ammonia has been removed is sent to the catalyst separation tank 12, and the dibutyl ether layer recovered by the decanter 14 is supplied and mixed to precipitate the copper catalyst. The deposited copper catalyst is separated by a filter 13 and circulated. The reaction liquid from which the copper catalyst has been separated is sent to a decanter 14, where it is separated into an upper dibutyl ether layer and a lower layer.
PPD and sodium iodide aqueous solution are separated.
The lower aqueous solution is sent to the extraction column 15 via conduit 16. AN is supplied to the extraction column 15 from the conduit 18.
An aqueous sodium hydroxide solution is supplied from the conduit 17, an AN solution of PPD is obtained from the upper part, and an aqueous solution of sodium iodide and sodium hydroxide is obtained from the lower part. AN of PPD obtained in extraction column 15
The solution is sent to an AN distillation column 19, where AN is recovered, and sent to an o-phenylenediamine (hereinafter abbreviated as OPD) removal tank 20. For example, thiourea is supplied from the conduit 21,
OPD is converted to high boiling products. The crude PPD obtained by converting OPD is sent to a distillation column 22 to remove low-boiling point impurities, and then sent to a distillation column 23 for purification.
PPD is obtained. High boiling point impurities are extracted from the lower part of the distillation column 23. The aqueous solution obtained from the lower part of the extraction column 15 is sent to the distillation column 24 to remove excess water, the concentrated sodium iodide is circulated to the anolyte tank 2, and the removed water is sent to the catholyte tank 4. It is circulated. (Effects of the Invention) As described above, according to the present invention, by adding ammonium phosphate, sodium phosphate, or potassium phosphate, the pH of the electrolyte aqueous layer is increased.
The current efficiency of the iodinated aromatic compound can be prevented from decreasing, and the current efficiency can be increased. Furthermore, the production of by-products can also be reduced.
Moreover, even more effects can be obtained by limiting the pH to a specific range. ammonium phosphate,
Add sodium phosphate or potassium phosphate;
The fact that the electrolytic reaction can now be carried out extremely stably for a long period of time is an extremely large advantage in industrial implementation. Moreover, by adding ammonium phosphate, sodium phosphate, or potassium phosphate, the voltage can be lowered and the power consumption rate can be improved.
By reacting the iodinated aromatic compound thus obtained with a nucleophile such as ammonia, aminophenol, cyan ion or hydroxy ion, the corresponding aromatic compound can be produced with the highest yield. Furthermore, when manufacturing PPD,
It is a product that is entrained in small amounts when the iodide produced after the amination reaction is recovered and circulated to the electrolytic system.
By suppressing the amount of PPD and keeping the concentration of PPD present in the electrolyte below a specific concentration, it has become possible to prevent the electrolytic reaction from deteriorating.
(This concept is the same in the case of producing other aromatic compounds.) In the above points, the method of the present invention is an extremely excellent industrial method for producing aromatic compounds. (Example) Next, the present invention will be explained in more detail with reference to Examples. Note that the measured values in the Examples and Comparative Examples were based on the following method. Current efficiency (%) = Number of moles of PIA generated x 2 / Amount of current flow (Faraday unit) x 100 p/o (mole ratio) = PIA generated / OIA generated In addition, (%) in Examples and Comparative Examples is as follows:
All values except current efficiency, recovery rate, conversion rate, and selectivity are percentages by weight. Example 1 As the anolyte, 75 g of sodium dihydrogen phosphate,
75g disodium hydrogen phosphate, sodium iodide
A mixture of 150 g of aniline, 300 g of aniline, and 1200 g of water was used and placed in the anolyte tank. 5 in the catholyte tank
% aqueous sodium hydroxide solution was added. The electrolyte in both tanks was circulated to the next electrolytic cell. The electrolytic cell consists of an anolyte and a cathode chamber separated by a diaphragm.The anode is a platinum-plated titanium plate, the cathode is an iron plate, and both electrodes have a current-carrying area of 1 cm x 100 cm, with a current-carrying area between the two electrodes. is 1cm×
Two 2 mm thick polyethylene plates with 100 cm openings were used, and a perfluorocarbon carboxylic acid type ion exchange membrane was placed in the center to form a cathode chamber and an anode chamber. The electrolytic cell had an electrolytic solution inlet and an outlet, and the electrolytic solution was flowed at a flow rate of 2 m/sec, and electrolysis was performed for 2 hours at a current density of 10 A/dm ² and an electrolysis temperature of 50°C. PH of anolyte water layer
was adjusted to 6.5 in advance, and NaOH was added to maintain the pH at 6.5 during electrolysis. The average voltage was 3.5V. After electrolysis, PIA in the electrolyte was analyzed by gas chromatography. As a result, the current efficiency was 94%. There were few PH changes during operation, and PH adjustment was easy. The p/o ratio of the iodoaniline produced was 24. Obtained by electrolytic reaction in a 500ml autoclave
A mixed solution of 30 g of PIA and 35 g of AN, 7.2 g of water, 3.5 g of cuprous iodide, and 65 g of ammonia were added. 5 at 75℃
Allowed time to react. The pressure was 25Kg/ ^cm2 . After the reaction was completed, excess ammonia was released to obtain a reaction solution. 14g of PPD was generated. 49 g of a 15% aqueous sodium hydroxide solution was added to the reaction solution and heated to 80° C. under reduced pressure to distill out 15 g of water and simultaneously remove ammonia. The PH in the aqueous layer was measured to be 13.1, and since sodium hydroxide remained, 35 g of dibutyl ether was added thereto, stirred, and the precipitate was filtered to recover the copper catalyst. 5.5g
It was hot. The liquid was separated into two layers. The upper layer contains dibutyl ether, 1% PPD, and copper.
It was 10ppm. The lower layer was mainly composed of AN, water, and sodium iodide, and contained 15% PPD.
The copper concentration was 20 ppm. The lower layer weighed 80 g and was extracted four times with 20 g of aniline. PPD on aniline layer
99% of the samples were extracted. The aniline solution was distilled under reduced pressure to obtain 12.6 g of PPD. Comparative Example 1 Electrolysis was carried out under the same conditions as in Example 1, except that sodium phosphate was removed from the anolyte composition. The voltage varied slightly between 4.1 and 4.5V and was unstable. The current efficiency was 86%. while driving
It was difficult to adjust the PH, and the PH fluctuated between 7.5 and 5.1.
The p/o ratio of the iodoaniline produced was 23.5. After the reaction was completed, the catholyte was observed, and although it was not separated in Example 1, a small amount of organic layer was separated. Example 2 Using the same electrolytic solution and electrolytic cell as in Example 1, the flow rate of the electrolytic solution was 2 m/sec, the electrolysis temperature was 50°C, and the current density was 10 A/sec.
Electrolysis was carried out at dm ² for 2 hours while changing the pH of the aqueous layer. The results are shown in Table 1.

[Table] Comparative Example 2 Electrolysis was carried out for 2 hours using the same electrolytic solution and electrolytic cell as in Comparative Example 1, and the same electrolytic conditions, but only the pH was changed. The results are shown in Table 2.

[Table] Note that even at pH 5.0 and 4.6, the organic layer was liquid and did not precipitate. However, at PH=4.6,
The organic layer became very small. This is probably due to the aniline salt being dissolved in the aqueous layer. At pH 7.8, 4-aminodiphenylamine and azobenzene were detected as a result of gas chromatography analysis. After the reaction, the catholyte was observed, and it was found that the organic layer was particularly separated at pH 5.0 and 4.6. Example 3 As an electrolyte, 70 g of potassium dihydrogen phosphate, 70 g of dipotassium hydrogen phosphate, 150 g of potassium iodide,
A mixed solution of 250 g of aniline and 1210 g of water was used and placed in an electrolyte tank. The pH of the aqueous layer was 6.0. The electrolytic cell consists of a titanium plate with platinum and titanium mixed, coated, and fired to form an oxide alloy as the anode, and an iron plate as the cathode, with a current-carrying area of 1 cm x 1 cm between the two electrodes.
An electrolytic chamber was formed by placing one 2 mm thick polyethylene plate with 100 cm openings. The electrolytic cell had an electrolytic solution inlet and an outlet, and the electrolytic solution was flowed at a flow rate of 2 m/sec, and electrolysis was performed for 2 hours at a current density of 10 A/dm ² and an electrolysis temperature of 50°C. No PH adjustment was performed during electrolysis. The pH of the aqueous layer after electrolysis was 6.5. The average voltage was 3.2V.
The current efficiency of PIA was 92%. Generate PIA p/
The o ratio was 25. Comparative Example 3 Of the electrolyte composition of Example 3, excluding phosphate,
Electrolysis was carried out for 2 hours in the same manner as in Example 3, except that an electrolytic solution containing 140 g of more water was used. No PH adjustment was performed during electrolysis. PH rose from 6.0 to 11.3. The average voltage was 4.4V and the current efficiency was 32%. Examples 4, 5, 6, 7 Comparative Example 4 PPD was added to the electrolyte composition of Example 1 at 0.1%, 0.5%,
The same as in Example 1 except that the diaphragm in the electrolytic cell of Example 1 was changed to a cation exchange membrane obtained by sulfonating polystyrene and dipinylbenzene copolymer reinforced with a glass fiber core material. Electrolysis was carried out for 2 hours. The results are shown in Table 3.

【table】

[Table] Example 8 After aminating PIA in Example 1 and removing the copper catalyst, two layers were separated, and PPD in the lower layer was extracted with AN. Into 75 g of the lower layer, 18 g of sodium iodide,
It contained 0.21g of PPD. Perform this reaction 10 times,
760g of recovered sodium iodide aqueous solution with similar composition
I got it. Using 630 g of this liquid, 75 g of sodium dihydrogen phosphate, 75 g of disodium hydrogen phosphate,
An anolyte was prepared by adding 720 g of water and 300 g of aniline. Other electrolysis conditions were the same as in Example 1, and electrolysis was performed for 2 hours. The pH of the electrolyte aqueous layer was maintained at 6.5. The voltage was 3.6V. The current efficiency of the generated PIA was 89%. Example 9 In the same manner as in Example 1, a mixed solution of 80 g of PIA obtained by electrolytic reaction and 120 g of aniline, as well as 40 g of water, 200 g of ammonia, and 6.4 g of cuprous iodide were placed in an autoclave.
was added and reacted at 100°C for 3 hours. pressure is 30
It was Kg/ ^cm2 . After the reaction, excess ammonia was released and 38g of PPD was produced in the residual liquid.
100 g of a 15% aqueous sodium hydroxide solution was added and heated to 80° C. under reduced pressure to distill off 60 g of water and at the same time remove ammonia. When the pH of the aqueous layer was measured, it was 12.9 and sodium hydroxide remained, so 16g of diisopropyl ether was added.
After adding and mixing, the precipitated copper catalyst was filtered under reduced pressure to recover 10.1 g of the copper catalyst. The liquid was separated into two layers. The upper layer was mainly composed of diisopropyl ether, but contained 10 ppm of copper. The lower layer is mainly composed of water, aniline, and sodium iodide, and is PPD.
It contained 36.5g of. The copper concentration was 20 ppm.
The lower layer weighed 260 g. The lower layer is 40g of aniline.
Extracted twice. 92% of PPD was extracted in the aniline layer. Distill aniline solution under reduced pressure to obtain 31g of PPD.
Obtained. After aniline extraction, the aqueous layer weighed 250 g and contained 50 g of sodium iodide and 2.9 g of PPD. Example 10 The reaction of Example 9 was repeated three times, and the recovered sodium iodide aqueous solution weighed 760 g, containing 150 g of sodium iodide and 5.8 g of PPD. To this recovered solution, 75 g of sodium dihydrogen phosphate, 75 g of disodium hydrogen phosphate, 590 g of water, and 300 g of aniline were added to prepare an anolyte. Otherwise, electrolysis was carried out in the same manner as in Example 1. However, a perfluorosulfonic acid type cation exchange membrane was used as the diaphragm. Electrolysis was performed for 2 hours, and the pH was maintained at 6.3. The voltage was 3.6V.
The current efficiency of PIA was 78%. Example 11 A reaction was carried out using 5.1 g of the decomposer recovered in Example 9. In a 500ml autoclave, add a mixture of 29g of PIA and 40g of AN obtained by electrolytic reaction, and 8g of water.
55 g of ammonia and the recovered catalyst obtained in Example 9 were added and reacted at 90°C for 6 hours. Pressure is 27Kg/ ^cm2・
It was G. After the reaction was completed, excess ammonia was released. 13.5g of PPD was generated in the residual liquid.
The response rate of PIA was 100%. Then, as in Example 1, 40 g of 15% NaOH and diethyl ether were added.
36g was added and treated, and 5.0g of copper catalyst was recovered.
The copper concentration in the two separated upper and lower layers is 15ppm,
It was 25ppm. The recovery rate of copper in the copper catalyst was 98%. Example 12 The reaction was carried out in the same manner as in Example 1, and after the amination reaction,
75 g of residual liquid from which excess ammonia was removed was obtained.
14.2g of PPD was generated. PIA reaction rate is 100
It was %. 60 g of water was added to the residual liquid, stirred to precipitate most of the copper catalyst, and 5.0 g of the copper catalyst was recovered by filtration under reduced pressure. When the mixture was separated into two layers, the upper layer weighed 40 g and contained 3000 ppm of copper and 7% ammonium iodide. The bottom layer is 95g, with 180ppm copper and 18.1% ammonium iodide.
It was hot. In addition, the lower layer contained 7.0g of PPD, so it was extracted with 35g of aniline, and 95g of PPD was extracted.
% was extracted. The extracted aniline and the above-mentioned upper layer were mixed and extracted with 40 g of water to extract 98% of ammonium iodide. obtained in this way
The copper content in the PPD aniline solution was 2000 ppm.
To this solution, 50 g of 15% sodium hydroxide and 70 g of dibutyl ether were simultaneously added and stirred to precipitate the copper catalyst, and 0.5 g of the copper catalyst was recovered by filtration. Next, two layers were separated, and the upper layer was an organic layer containing dibutyl ether as a main component and containing 20 ppm of copper. The main component of the lower layer is aqueous sodium hydroxide solution, with copper as the main component.
It was 15ppm and contained 11g of PPD. This lower layer was extracted with 60 g of aniline, and 11.5 g of PPD was recovered. This aniline solution was distilled to obtain 10.3 g of PPD. The recovery rate of copper in the copper catalyst was 97%. Example 13 An electrolytic reaction was carried out in the same manner as in Example 1. Next, the electrolyte solution was separated into two layers of oil and water, and the oil layer was isolated. Aniline was distilled off from the oil layer under reduced pressure to concentrate the PIA concentration to 90% by weight. 28.5 g (0.115 mol as PIA) of this liquid, 10.0 g (0.205 mol) of sodium cyanide, 1.0 g of cuprous cyanide.
(0.01 mol), 250 g of dimethylformamide in 500 ml
The mixture was placed in a small autoclave, the inside of the autoclave was purged with nitrogen, and the mixture was stirred at 150°C for 10 hours. After the reaction was completed, the reaction solution was quantified by gas chromatography, and the conversion rate of PIA was 80%.
The selectivity rate of PABN was 98%. Example 14 Concentrated from electrolyte in the same manner as Example 13
The aniline solution of PIA was taken out. This solution 28.5
g (0.115 mol as PIA), potassium cyanide
10.0g (0.15mol), cuprous cyanide 2.0g (0.010
250 g of dimethyl sulfoxide (mol) was placed in a 500 ml small autoclave, the inside of the autoclave was purged with nitrogen, and the mixture was stirred at 180°C for 6 hours. After the reaction is complete,
When the reaction solution was quantified by gas chromatography, the conversion rate of PIA was 100% and the selectivity of PABN was 99%. Example 15 Electrolysis was carried out in the same manner as in Example 3, and then the electrolytic solution was separated into two layers of oil and water, and the oil layer was isolated. Potassium cyanide 11.0g (0.165mol) in 250g oil layer,
1.0 g (0.010 mol) of cuprous cyanide was placed in a 500 ml small autoclave, the inside of the autoclave was purged with nitrogen, and the mixture was stirred at 180°C for 12 hours. After the reaction was completed, the reaction solution was quantified by gas chromatography, and the conversion rate of PIA was 75%, and the selectivity of PABN was 95%. Example 16 PIA was synthesized in the same manner as in Example 1, and then
PABN was synthesized in the same manner as in Example 13. After the reaction was completed, 250 g of aniline and 500 g of water were added to the reaction solution, and the mixture was separated into two layers of oil and water by passing through the crystals.
After adding 100 g of aniline to the aqueous layer and extracting organic matter from the aqueous layer five times, the aqueous layer was separated. Next, the separated aqueous layer and sodium dihydrogen phosphate
75 g, disodium hydrogen phosphate 75 g, sodium iodide 125 g, aniline 300 g, and water 800 g,
It was used as an anolyte. The electrolytic reaction was carried out in the same manner as in Example 1 except for this preparation. The average voltage is
3.5V, and the current efficiency of PIA generation was 89%. The p/o ratio of the iodoaniline produced was 25. Next, the electrolytic solution was separated into two layers of oil and water, the oil layer was isolated, and then PABN was synthesized in the same manner as in Example 13 using this oil layer. The conversion rate of PIA was 100% and the selectivity of PABN was 98%. Example 17 An electrolytic reaction was carried out in the same manner as in Example 1, and then the electrolytic solution was separated into two layers of oil and water, and the oil layer was isolated. Aniline was removed from the oil layer by vacuum distillation, and the PIA concentration was concentrated to 90% by weight. Next, 3.2 g (0.03 mol) of m-aminophenol, 2.0 g (0.03 mol) of potassium hydroxide, 10 g of dimethyl sulfoxide, and 10 g of toluene were added to 100 ml of 4
The mixture was placed in a neck flask and stirred at 130°C for 3 hours under a nitrogen stream while allowing toluene to flow out. reaction solution
Cool to 100℃ and add 0.4 cup of copper iodide to a four-necked flask.
g, 4.6 g (0.02 mol as PIA) of a liquid obtained by concentrating the oil layer obtained by electrolysis, and 10 g of dimethyl sulfoxide were added, and the mixture was stirred at 100° C. for 3 hours under a nitrogen stream. After the reaction was completed, the reaction solution was analyzed by liquid chromatography, and the yield of 3,4′-DADPE was found to be based on PIA standards.
It was 50%. Example 18 m-aminophenol 3.2g (0.03mol), sodium hydroxide 1.2g (0.03mol), aniline 10g,
10 g of monochlorobenzene was placed in a 100 ml four-necked flask, and the mixture was stirred at 150° C. for 3 hours while the monochlorobenzene was flowing out. reaction solution
Cool to 100℃ and add 0.4 cuprous oxide to a four-necked flask.
g, 4.6 g of the concentrate obtained in Example 17 (0.02 g as PIA)
mol), add 10g of dimethyl sulfoxide, and heat to 100°C.
The mixture was stirred for 3 hours under a nitrogen stream. After the reaction is complete, when the reaction solution is analyzed using liquid chromatography,
The yield of 3,4'-DADPE was 30% based on PIA standards. Example 19 m-aminophenol in Example 17 was converted to p-
The reaction was carried out in exactly the same manner as in Example 17 except that aminophenol was used. The yield of 4,4'-DADPE was 35%. Example 20 The m-aminophenol in Example 18 was converted to p-
The reaction was carried out in exactly the same manner as in Example 18 except that aminophenol was used. The yield of 4,4'-DADPE was 20%. Comparative Example 5 m-aminophenol in Example 17 was replaced with p-
The reaction was carried out in exactly the same manner as in Example 17, except that aminophenol was used and p-iodoaniline was replaced with p-chloroaniline. The yield of 4,4'-DADPE was 2%. Example 21 An electrolytic reaction was carried out in the same manner as in Example 1, and then the electrolytic solution was separated into two layers of oil and water, and the oil layer was isolated. Aniline is removed from the oil layer by distillation under reduced pressure.
The PIA concentration was concentrated to 90% by weight. 33g of this concentrate (0.013mol as PIA), 4.0g of potassium hydroxide, 20g of water, 0.5g of cuprous oxide
(0.0035 mol) was placed in a 100 ml micro autoclave and stirred at 120°C for 6 hours. After the reaction is complete,
Phosphoric acid was added to adjust the pH of the aqueous layer to 7, followed by extraction with aniline. GC analysis of the aniline layer showed that the conversion rate of PIA was 95% and the selectivity to p-aminophenol was 60%. Example 22 An electrolytic reaction was carried out in the same manner as in Example 21, and the oil layer of the electrolyte was concentrated to a PIA concentration of 50% by weight. 10g of this concentrate (0.0228 mol as PIA), 3.0g of potassium hydroxide, 20g of water, 0.20g of cuprous oxide
(0.0014 mol) was placed in a 100 ml micro autoclave and stirred at 120°C for 10 hours. After the reaction is complete,
The same treatment as in Example 21 was performed and GC analysis was performed.
The conversion rate of PIA was 40% and the selectivity to p-aminophenol was 85%. Example 23 As an electrolyte, 70 g of potassium dihydrogen phosphate, 70 g of dipotassium hydrogen phosphate, 300 g of potassium iodide,
A mixed solution containing 1200 g of water was used. The electrolytic cell consists of a titanium plate with platinum and titanium mixed, coated, and fired to form an oxide alloy for the anode, and an iron plate for the cathode, with an opening between the two electrodes so that the current-carrying area is 1 cm x 100 cm. An electrolytic chamber was formed by placing one polyethylene plate with a thickness of 2 mm. The electrolytic cell has an electrolyte supply inlet and an outlet, and the electrolyte has a flow rate of
Flowing at 2 m/s, current density 10 A/dm ² , electrolysis temperature
Electrolysis was carried out at 50°C for 1 hour. No PH adjustment was performed during electrolysis. The average voltage was 3.0V. The pH in the electrolyte changed from 6.5 to 7.5. This electrolytic solution was taken out, 53 g of phenol was added, and the mixture was stirred at 30° C. for 30 minutes. After the reaction was completed, 50 g of phosphoric acid and 500 g of benzene were added to the reaction solution, and the product was extracted into a benzene layer. GC analysis of the benzene layer revealed p-iodophenol, o-iodophenol, 2,4-
Diiodophenol was produced. The yield based on the amount of current applied during electrolysis was 57% for p-iodophenol, 32% for o-iodophenol, and 2% for 2,4-diiodophenol. After benzene was removed by evaporation from the reaction solution, a solution containing iodophenol from which benzene had been removed, 80 g of ammonia, 7 g of cuprous iodide, and 8 g of water were added in the same manner as in Example 1. The reaction was carried out at 100°C for 8 hours. The pressure was 30Kg/ ^cm2 . After the reaction was completed, excess ammonia was released to obtain a reaction solution. GC analysis of the reaction solution revealed p-aminophenol, o-
Aminophenol was produced at 96% and 94% based on p-iodophenol and o-iodophenol, respectively. Comparative Example 5 Of Example 23, 70g of potassium dihydrogen phosphate
to 140g, and 70g of dipotassium hydrogen phosphate to 0.
An electrolytic reaction was carried out in exactly the same manner as in Example 23, except that g was changed, and a reaction with phenol was also carried out. The pH of the electrolyte varied from 4.9 to 6.0. When the reaction with phenol was stirred at room temperature for 15 minutes, the reaction did not proceed at all, and when stirred at 50° C. for 5 hours, p-iodophenol and o-iodophenol were slightly produced. Comparative Example 6 Among Example 23, 70g of potassium dihydrogen phosphate
to 0g, and 70g of dipotassium hydrogen phosphate to 35g.
except that 30g of potassium hydroxide was added.
An electrolytic reaction was carried out in exactly the same manner as in Example 23, and a reaction with phenol was also carried out. The pH in the electrolyte is
It changed from 11.1 to 11.6. After the reaction with phenol was completed, 100 g of phosphoric acid and 500 g of benzene were added to extract the product into the benzene layer. Analysis of the benzene layer reveals that the yield based on the amount of current applied during electrolysis is p-
Iodophenol 26%, o-iodophenol 11
%, and 2,4-diiodophenol was 19%. Example 24 As an electrolyte, 25 g of sodium dihydrogen phosphate,
75g disodium hydrogen phosphate, sodium iodide
Example except that a mixture of 300g and 1200g of water was used.
Electrolysis was carried out in exactly the same manner as in 23. The average voltage is
It was 3.1V. The pH of the electrolyte changed from 8.1 to 9.0. Take out this electrolyte and add 6.0g of Anniesole.
was added and stirred at 80°C for 15 hours. After the reaction was completed, unreacted iodine was treated with an aqueous sodium thiosulfate solution and extracted with 500 g of benzene. GC the benzene layer
Analysis revealed that only p-iodoanisole was produced. No o-body was generated. The yield based on the amount of current applied during electrolysis was 26%. This reaction solution was reacted with ammonia in exactly the same manner as in Example 23. The yield of p-aminoanisole was 94% based on p-iodoanisole. Comparative Example 7 In Example 24, sodium dihydrogen phosphate 25
Change g to 150g and add 75g of disodium hydrogen phosphate.
The electrolytic reaction was carried out in exactly the same manner as in Example 24, except that the amount was changed to 0 g, and the reaction with anisole was also carried out in the same manner. GC analysis after the completion of the reaction revealed that no anisole iodide was produced. Comparative Example 8 Example 24 except that 100 g of sodium hydroxide was added instead of adding sodium dihydrogen phosphate and disodium hydrogen phosphate in Example 24.
An electrolytic reaction was carried out in exactly the same manner as described above, and a reaction with anisole was also carried out. After the reaction was completed, phosphoric acid was added to the reaction solution to make it neutral, followed by benzene extraction, and the benzene layer was analyzed by GC, but no anisole iodide was produced. Example 25 As the anolyte, 70 g of sodium dihydrogen phosphate,
70g disodium hydrogen phosphate, sodium iodide
Electrolysis was carried out for 2 hours using the same container and electrolytic conditions as in Example 1, except that a mixed solution of 300 g and 1200 g of water was used. The pH of the anolyte was adjusted to 6.5 in advance.
The average voltage was 3.2V. To 200 g of an aqueous solution with the same composition as the anolyte prepared above,
Add 38.7g of AN and heat to 40℃ while stirring.
After the electrolysis, the anolyte was added dropwise over 10 minutes and stirred for 30 minutes. After the reaction, PIA was precipitated in the reaction solution, so it was separated and analyzed, resulting in 72.9 g of PIA (yield: 92
%) and contained 15% water. Also,
The response rate of AN was 98%. The pH of the water layer after the reaction is
It was 5.8. In a 500ml autoclave, 30g of PIA obtained by precipitation and separation by iodination reaction, 10g of water, and 2 cuprous hydroxide.
g, and 50 g of ammonia were added. The reaction was carried out at 80°C for 6 hours. The pressure was 30Kg/ ^cm2 . After the reaction is complete,
Excess ammonia was released to obtain a reaction solution.
14g of PPD was generated. Add 55g of 15% sodium hydroxide to the reaction solution, heat to 80℃ under reduced pressure, and add water.
Ammonia was removed at the same time as 30 g was distilled out. The pH in the aqueous layer was 13.5. After adding 100 g of water to dissolve the precipitated PPD, the precipitated copper catalyst was filtered and recovered. The copper concentration in the liquid was 20 ppm. When the liquid was extracted four times with 20 g of aniline, 98% of PPD was extracted.

[Brief explanation of drawings]

The drawing is a flow sheet illustrating one embodiment of the invention.

Claims (1)

[Scope of Claims] 1. Iodide that is soluble in water and obtained by electrolytically oxidizing an electrolyte iodide in an electrolytic solution whose pH is maintained at 5.5 to 10.0 with ammonium phosphate, sodium phosphate, or potassium phosphate. Iodine is reacted with an aromatic compound having an amino group, an N-alkylamino group, an N,N'-dialkylamino group, a hydroxy group, or an alkoxy group, and the resulting iodinated aromatic compound is treated with ammonia, aminophenol, and cyanide. A method for producing an aromatic compound, which comprises reacting with an ion or a hydroxy ion as a nucleophile. 2 In an electrolytic solution whose pH is maintained at 5.5 to 10.0 with ammonium phosphate, sodium phosphate, or potassium phosphate, water-soluble iodide of the electrolyte is electrolytically oxidized to produce iodine, and then amino group, N-alkylamino group, N,
The method according to claim 1, which comprises reacting with an aromatic compound having an N'-dialkylamino group, a hydroxy group, or an alkoxy group. 3. The method according to claim 1 or 2, wherein the iodide is ammonium iodide, sodium iodide, or potassium iodide. 4 While maintaining the pH of the aqueous phase in the electrolytic solution at 5.5 to 6.9, iodine that is soluble in water and obtained by electrolytically oxidizing the iodide of the electrolyte is converted into an amino group, an N-alkylamino group, or an N-alkylamino group. The method according to claim 1, which comprises reacting with an aromatic compound having an N'-dialkylamino group. 5 While maintaining the pH of the water phase in the electrolytic solution at 6.5 to 10.0, iodine that is soluble in water and obtained by electrolytic oxidation of iodide in the electrolyte is reacted with an aromatic compound having a hydroxy group or an alkoxy group. The method according to claim 1, wherein 6 The aromatic compound having an electron donating group is aniline, the iodinated aromatic compound is p-iodoaniline, the nucleophile is ammonia, and the aromatic compound to be produced is p-phenylenediamine. A method according to certain claims 1 or 2. 7. React p-iodoaniline with ammonia in the presence of a copper catalyst, water, and aniline, and after the reaction is complete,
7. The method according to claim 6, wherein ammonia is removed from the reaction solution, and ethers and alkali hydroxide are added to separate and recover the copper catalyst. 8. The method according to claim 7, wherein the copper catalyst is a cuprous compound. 9. The method according to claim 7, wherein the ether has 6 to 8 carbon atoms. 10 Collect ammonium iodide, which is a by-product when p-iodoaniline and ammonia are reacted to obtain p-phenylenediamine, and if necessary, react with alkali hydroxide to form alkali iodide, which is then used for electrolysis in the previous step. 7. The method according to claim 6, wherein p-phenylenediamine is used as an iodide in the reaction and the concentration of p-phenylenediamine mixed in the electrolytic solution is maintained at 0.5% by weight or less.