JPS63169394A - Production of 1-aminoanthraquinone - Google Patents

Abstract

PURPOSE:To produce high purity 1-aminoanthraquinone with high selectivity in a high yield by subjecting 1-nitronaphthalene to liq. phase oxidation with an acidic aq. soln. contg. ceric ions to produce 5-nitro-1,4-naphthoquinone. CONSTITUTION:1-Nitronaphthalene is subjected to liq. phase oxidation at about 0-80 deg.C with an acidic aq. soln. contg. ceric ions and having 0.3-10mol/l acid concn. preferably under radiated ultrasonic waves of >=10kHz frequency. Crystals contg. 5-nitro-1,4-naphthoquinone and an acidic aq. soln. contg. cerium ions are separated from the resulting reaction product mixture. The 5-nitro-1,4- naphthoquinone and 1,3-butadiene are brought into the Diels-Alder reaction at about 0-250 deg.C to deposit crystals contg. 5-nitro-1,4,4a,9a- tetrahydroanthraquinone. The crystals are separated and reduced at about 50-150 deg.C with a reducing agent. The reduced crystals contg. 1- aminoanthraquinone are separated and purified.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides novel 1-nitronaphthalene as a raw material.
This invention relates to a method for producing aminoanthraquinone. More specifically, 5-nitro-1,4- obtained by liquid phase oxidation of 1-nitronaphthalene using an acidic aqueous solution containing ceric ions (hereinafter referred to as "ceric ion-acidic aqueous solution") 5-nitro-1゜4 by Diels-Alder reaction of naphthoquinone and 1,3-butadiene
．． 1, characterized in that 4a, 9a-tetrahydroanthraquinone is produced and further reduced using a reducing agent.
- A method for producing aminoanthraquinone. 1-aminoanthraquinone is industrially useful as an intermediate for anthraquinone dyes and the like.

[Prior Art] A method for producing 1-aminoanthraquinone using anthraquinone as a starting material includes a method of synthesizing anthraquinone-1-sulfonic acid obtained by sulfonation of anthraquinone by ammonolysis (Japanese Patent Application Laid-Open No. 48-4455, 1977-70732, Japanese Patent Publication [50-111059]
, 7> To synthesize 1-nitroanthraquinone by nitration of thora*/n with concentrated nitric acid or mixed acid etc.
-4784, JP-A-57-193426, JP-A-58-
35498. JP-A-58-150545) There are known methods in which the reaction mixture is then reacted with ammonia or reduced using alkali sulfide or alkali hydrosulfide. However, since the sulfonation method uses a mercury catalyst in the sulfonation step, there are problems in terms of working environment, pollution, etc. In addition, the nitration method uses a large amount of sulfuric acid and 1i1N acid, which causes many problems in terms of handling and waste liquid treatment, and the 1-aminoanthraquinone obtained does not contain by-products such as diamino and 2-amino acids. It is not an industrially advantageous method because it is contained in large amounts and requires complex purification operations to be used as an intermediate for dyes.

In addition, 5-nitro-1,4-naphthoquinone is reacted with 1゜3-butadiene and Diels-Alder to produce 5-nitro-1,4-naphthoquinone.
A method for producing 1-aminoanthraquinone by oxidizing 1,4,4a,9a-tetrahydroanthraquinone is also known (JP-A-51-32551). This method improves the above-mentioned drawbacks and is advantageous in terms of working environment and pollution.

On the other hand, as a method for producing 5-nitro-1,4-naphthoquinone, generally, an aromatic compound is oxidized in a liquid phase using a ceric ion-acidic aqueous solution to obtain the corresponding quinones. A method for producing 1,4-naphthoquinone by oxidizing naphthalene dissolved in an organic solvent immiscible with ceric ion using an acidic aqueous solution (Japanese Patent Publication No. 49
-34978 Publication), ■ Powdered naphthalene is mixed with a dispersant to make the second A method for producing 1,4-naphthoquinone characterized by suspending it in an aqueous solution of a lithium salt (Japanese Unexamined Patent Publication No. 56-61321) is known, and it is possible to apply this method. As the ceric ion-acidic aqueous solution used in these oxidation reactions, a ceric ammonium nitrate-nitric acid aqueous solution or a cerium sulfate-sulfuric acid aqueous solution is generally used. Further, the process of the liquid phase oxidation reaction includes an electrochemical regeneration process as a method of regenerating cerium ions produced after the liquid phase oxidation reaction into cerium ions.

[Problems to be Solved by the Invention] In the method for producing 1-aminoanthraquinone using 5-nitro-1,4-naphthoquinone as a starting material,
Unless a highly purified nitro-1,4-naphthoquinone is used, a highly purified 1-aminoanthraquinone product cannot be obtained.

On the other hand, in a method for producing 5-nitro-1,4-naphthoquinone in which 1-nitronaphthalene is oxidized in a liquid phase using a ceric ion-acidic aqueous solution, ceric ion-
The higher the concentration of ceric ions in the acidic aqueous solution or the higher the oxidation reaction temperature, the higher the reaction rate, which is advantageous in terms of the yield of the desired oxide per unit time. From the viewpoint of the coordination of things, the lower the concentration of ceric ions in the ceric ion-acidic aqueous solution, or the lower the oxidation reaction temperature, the more advantageous it is. When is a nitric acid aqueous solution, in the step (e) of electrolytically oxidizing ceric ions to regenerate them to ceric ions, coexisting nitrate ions are reduced to nitrite ions and ammonium ions at the cathode by electrolysis. As a result, the concentration of each ion changes, the pH of the solution changes, and in extreme cases, hydrolysis occurs.Along with these complex behaviors, the ability of the ceric ion-acidic aqueous solution as an oxidizing agent also changes. , and the accumulation of these side reaction products may also be a factor, resulting in the conversion of 1-nitronaphthalene to 5-nitro-1,
It affects not only the reaction rate to 4-naphthoquinone but also the selectivity, and further affects the yield and purity of 1-aminoanthraquinone. Therefore, the settings of the liquid phase oxidation reaction conditions must also be varied, and in actual operation, it becomes necessary to periodically analyze and adjust the liquid composition and further replace the liquid. Furthermore, anodic reactions other than the oxidation of ceric ions result in a decrease in the current efficiency for the purpose of producing ceric ions, and deterioration of the electrode occurs in a more complicated and serious manner. The same side reactions at the electrode and the inconveniences caused by them can be applied to other ceric ion-acidic aqueous solutions.

The present invention solves the above drawbacks by obtaining 5-nitro-1,4-naphthoquinone with few by-products from 1-nitronaphthalene, and further reducing it by subjecting it to a Diels-Alder reaction with 1,3-butadiene. The present invention provides a method for obtaining highly selective 1-aminoanthraquinone in a highly productive layer (and advantageous in terms of working environment and pollution, etc.).

[Means for Solving the Problem] As a result of intensive study on the drawbacks of the conventional method, the present inventors discovered that cerium was used as the anolyte in the step (e) of oxidizing the recovered cerium ions to ceric ions. An acidic aqueous solution containing ions is used as a catholyte, and an electrolyte is used as a catholyte.
By electrolytically oxidizing using an ion exchange membrane as a diaphragm, a high-quality ceric ion-acidic aqueous solution is obtained, which improves the selectivity and productivity of the target product in each subsequent process, and ultimately produces fewer by-products. We have discovered a method for producing 1-aminoanthraquinone. That is, the present invention is a) a step of oxidizing 7-nitronaphthalene in a liquid phase using an acidic aqueous solution containing ceric ions.

5-nitro- from the reaction mixture obtained in step a)
1. A step of separating crystals containing 4-naphthoquinone from an acidic aqueous solution containing cerium ions.

5-nitro-1,4-naphthoquinone obtained in step c) is subjected to a Diels-Alder reaction with 1,3-butadiene to produce 5-nitro-1,4,4a.

Crystallization of crystals containing 9a-tetrahydroanthraquinone,
Separation process.

2) 5-nitro-1,4°4a obtained in step c),
A step of reducing 9a-tetrahydroanthraquinone using a reducing agent and then separating and purifying crystals containing 1-aminoanthraquinone.

e) Electrolytically oxidize an acidic aqueous solution containing cerous ions as an anolyte, an electrolyte as a catholyte, and an ion exchange membrane as a diaphragm, and oxidize cerous ions in the acidic aqueous solution to ceric ions. The process of sending the product to step (a).

This is a method for producing 1-aminoanthraquinone, characterized by comprising: This will be explained in more detail below.

The step (b) of oxidizing 1-nitronaphthalene in a liquid phase using a ceric ion-acidic aqueous solution is carried out under strong II7 stirring using a stirrer, external circulation, gas blowing, or the like.

The step is preferably carried out in combination with ultrasound irradiation. Ultrasonic irradiation allows a higher reaction rate than simple forced stirring, lowers the reaction temperature or shortens the reaction time, increases productivity, and allows the reaction to proceed with high selectivity. . When combining ultrasonic irradiation, it is preferable that the ultrasonic wave has a frequency of 10 KH2 or more, and the irradiation method can be either an external irradiation method or an internal irradiation method.
An HE having an output can be used, and the ultrasonic radiator may be of any type such as a flat plate type, ring type, or disk type. Irradiation can be carried out continuously or intermittently during the reaction, and it is also effective to carry it out only in the latter stage of the reaction when the reaction rate decreases.

The preferred reaction temperature is usually 0 to 80°C, more preferably 1
The temperature is 5 to 60°C. If the temperature is too low, the reaction rate decreases, and if the temperature is too high, it is disadvantageous in terms of hydrolysis of the ceric salt, contamination of side reaction products such as polymerization, coloring, or corrosion of the equipment.

Regarding the acid concentration of the ceric ion-acidic aqueous solution, if it is too low, the ceric ions will become unstable, while if it is too high, it is disadvantageous in terms of corrosion of the equipment, so the M temperature in the acidic aqueous solution is preferably The range is from 0.3 to 10 mol/l, more preferably from 0.5 to 5 mol/l. As the acid in the acidic aqueous solution, an acid corresponding to the anion forming the ceric ion supply source can be used, but other acids can also be added. For example, sulfuric acid, nitric acid, etc. can be used alone or Can be used in combination.

Further, as the ceric ion-acidic aqueous solution, various acidic aqueous solutions of ceric salts can be used. Alternatively, a ceric ion-acidic aqueous solution obtained by dissolving a ceric salt such as ammonium cerous nitrate, cerous nitrate, or cerous sulfate in an acidic aqueous solution and oxidizing the solution can also be used.

Ceric ammonium nitrate (, (NH4)2[Ce
(NO3)6 ) - When using a nitric acid aqueous solution, as mentioned above, the solubility of ceric ammonium nitrate in water is relatively high, so the concentration of ceric ions can be maintained at a high level even at low temperatures, and a sufficient reaction rate and high It can be reacted selectively and can be suitably used. Further, a ceric nitrate-nitric acid aqueous solution obtained by dissolving ceric nitrate in an aqueous nitric acid solution and oxidizing the solution can also be suitably used since it can maintain a high concentration of ceric ions. In these cases, the ceric ion concentration in the acidic aqueous solution is preferably 0.
The range is 1 to 6 mol/l, more preferably 0.2 to 5 mol/l. If the concentration is too low, the oxidizing power will be weak, the reaction rate will be low, and the amount of reaction liquid will also be large, which is disadvantageous. On the other hand, if it is too high (a large amount of cerium salt is dissolved), the viscosity of the liquid will increase, which may interfere with the opening operation in the process.

In the step (a), 1-nitronaphthalene may be dissolved in an organic solvent that is immiscible with water, or 1-nitronaphthalene alone may be added without using a solvent, and the system may be in the form of a liquid or a slurry. But that's fine. Examples of the organic solvent include aromatic hydrocarbons or substituted products thereof such as benzene, tert-butylbenzene, and chlorobenzene, aliphatic hydrocarbons such as cyclohexane, n-hexane, n-pentane, and n-octane, carbon tetrachloride, Organic solvents such as chlorinated aliphatic hydrocarbons such as chlormethylene and dichloroethane can be used. 1. In step 0), crystallize 5-nitro-1,4-naphthoquinone crystals from the reaction mixture obtained in step a),
The crystals and the filtrate are separated by centrifugation, filtration, etc., and if necessary, the acidic aqueous solution containing cerium ions and the organic phase are further separated from the filtrate, and the crystals are transferred to step c). It is sent to the process e). The organic phase mainly consists of the solubility of 5-nitro-1,4-naphthoquinone, unreacted 1-nitronaphthalene, or the solvent used in step (a), and is sent to step (e) without separation from the aqueous phase. Otherwise, it is separated and recovered and returned to step (a).

In step c), 5-nitro-1,4-naphthoquinone is converted into 1,
Diels-Alder reaction with 3-butadiene. The reaction is carried out using a suitable solvent that dissolves 5-nitro-1,4-naphthoquinone and 1,3-butadiene. Examples of such solvents include aromatic hydrocarbons such as benzene, toluene, and xylene, halogenated hydrocarbons such as dichloroethane, carbon tetrachloride, and dichlorobenzene, ethers such as ethyl ether and diphenyl ether, dioctyl phthalate, and methyl acetate. etc., ketones such as acetone and methyl ethyl ketone, alcohols such as methanol and ethanol, and cellosolves such as methyl cellosolve and ethyl cellosolve. 5-nitro-1,4
The Diels-Alder reaction between naphthoquinone and 1,3-butadiene is generally carried out at a temperature of 0 to 250°C, preferably 30 to 150°C, as in the case of other aromatic quinone compounds. If the reaction temperature is too high, the solubility of 1°3-butadiene will decrease, making it difficult for the reaction to proceed, and 5-nitro-1,4,4a will be produced.

9a-Tetrahydroanthraquinone is converted into other substances through side reactions such as isomerization and dehydrogenation, and the raw material 5-nitro-
Side reactions such as polymerization of 1,4-naphthoquinone and 1,3-butadiene also occur, reducing reaction selectivity. On the other hand, if it is too low, the reaction rate will decrease.

The reaction pressure depends on the solubility of 1,3-butadiene, etc., but is usually 12C1/α2 or less, more generally 0 to 20
This is done within the range of Ky/α2. The reaction is completed more quickly when the amount of 1.3-butadiene used is in excess of 5-nitro-1,4-naphthoquinone, but if it is too much, it is not economical in terms of equipment, and preferably ~20 mole times,
More preferably, the amount is 1.1 to 10 times the mole. Also,
The reaction time is limited by constraints such as the concentration of 1,3-butadiene, reaction temperature, and reaction pressure, and the optimum reaction time is selected for each.

5-nitro-1,4,4a, 9a obtained in step c)
-Tetrahydroanthraquinone is reduced in step 2) and easily becomes 1-aminoanthraquinone. Reducing agents include hydrogen, relatively unstable hydrogen compounds such as hydrogen iodide, hydrogen sulfide, lithium aluminum hydride, and sodium borohydride; - lower oxides or lower oxygen such as carbon oxide, sulfur dioxide, and sulfite; Acid salts, sulfur compounds such as sodium sulfide, sodium hydrosulfide, ammonium sulfide, alkali metals, highly electropositive metals such as magnesium and calcium, or their amalgams, iron (■), tin (■), titanium (■) ), salts of metals in a low valence state such as chromium (II), aldehydes, and organic compounds that act as reducing agents such as formic acid and oxalic acid are used.

In step 2), a water-soluble solvent such as acetone, methanol, ethanol, isopropanol, methyl cellosolve, etc. may be used as the solvent, or simply water may be used. In addition, water-immiscible solvents such as toluene and xylene can also be used, but in this case, ammonia, aliphatic primary amines such as methylamine and ethylamine, aliphatic secondary amines such as diallylamine and diethylamine, trimethylamine and triethylamine are used. Addition of organic amines such as aliphatic tertiary amines such as allylamine, aliphatic unsaturated amines such as allylamine, diallylamine, alicyclic amines such as cyclopropylamine, cyclobutylamine, aromatic amines such as aniline, benzylamine, diphenylamine, etc. do it. The reaction is usually carried out at 50 to 150°C, preferably 60 to 120°C, although it depends on the solvent used. If the reaction temperature is too high, the raw materials 5-nitro-1.4.4a and 9a-tetrahydroanthraquinone will be converted into other substances through side reactions such as isomerization and dehydrogenation, and if the reaction temperature is too low, the reaction rate will decrease. do.

The electrolytic oxidation step (e) is a step in which ceric ions in an acidic aqueous solution containing ceric ions are oxidized to ceric ions, and regenerated or prepared as the ceric ion-acidic aqueous solution in step (a). be. In the present invention, this step is performed using an ion exchange membrane as a diaphragm.

As mentioned above, when a cerium ion-acidic aqueous solution comes into contact with the cathode, various ions are generated by electrolytic oxidation, especially if the cerium ion-acidic aqueous solution contains nitrate ions.
! It behaves sloppily and causes various inconveniences. By using an ion exchange membrane as a diaphragm, it is possible to prevent nitrate ions or other ions contained in the anolyte from coming into contact with the cathode, and also to prevent the catholyte from being reduced by the cathode and producing any by-products. Even if they are generated, they are separated by the diaphragm and do not mix into the anolyte, thus preventing these inconveniences. Note that the acidic aqueous solution containing cerium ions referred to herein includes not only the acidic aqueous solution containing the cerium ions separated in the step (1), but also an acidic aqueous solution in which a new or supplementary cerium salt is dissolved.

Next, an embodiment based on the present invention will be explained in detail with reference to FIG. 1. FIG. 1 is a flow sheet for continuously producing 1-aminoanthraquinone using a solvent in a liquid phase oxidation reaction (if no solvent is used, step 6.8 can be omitted). 33 in Figure 1, 1 is a catholyte tank, 2 is an electrolyte tank, 3 is an anolyte tank, 4 is a 1-nitronaphthalene tank, 5 is a liquid phase oxidation reactor, 6 is a solvent tank, 7 and 13 are filtration 8 is a separation column, 9 is a Diels-Alder reactor,
1o is a 1,3-butadiene tank, 11 is a reduction reactor,
12 is a reducing agent tank, 14 is a waste liquid tank, and 15 is a product (
1-aminoanthraquinone) tank.

The cathode and anode of the electrolytic cell 2 are separated by a diaphragm of an ion exchange membrane, and on the cathode side, the catholyte in the catholyte tank 1 is introduced into the electrolytic cell 2 through a line 16, and from the electrolytic cell 2 into the line 1.
7 to the catholyte tank 1, and on the other hand, on the interelectrode side, the acidic aqueous solution containing cerium ions in the anolyte tank 3 is introduced from line 18 to the electrolytic cell 2, and electrolysis 1f! 2 to the anolyte tank 3 via line 19. During this time, electrolysis is performed to oxidize the cerium ions in the acidic aqueous solution to cerium ions. The anolyte containing a predetermined concentration of ceric ions is passed from the anolyte tank 3 through line 20, the 1-nitronaphthalene is passed from the 1-nitronaphthalene tank 4 through line 21, and the solvent is passed from the solvent tank 6 through line 22. Introduced into liquid phase oxidation reactor 5, 1-
Catalytic liquid phase oxidation of nitronaphthalene with ceric ions is carried out. The reaction product is passed through a filter 7,
The crystals of nitro-1,4-naphthoquinone are introduced into the Diels-Alder reactor 9 via the inlet 27. on the other hand,
The furnace liquid is introduced into the separation column 8 via a line 24, the fi layer is circulated via a line 26 to the solvent tank 6, and the acidic aqueous solution layer containing the first and second cerium ions is transferred via a line 25 to the anolyte tank 3. The cerium ions are returned to the electrolytic cell 2 and recycled into cerium ions. The 5-nitro-1,4-naphthoquinone introduced into the Diels-Alder reactor 9 is 1.3-
A Diels-Alder reaction is carried out with 1,3-butadiene introduced from the butadiene tank 10 at an appropriate temperature and pressure in the presence of an appropriate solvent. The 5-nitro-1,4,4a,9a-tetrahydroanthraquinone obtained by the reaction is sent via line 29 to reduction reactor 11, where it is fed with a suitable reducing agent introduced via line 30 from reducing agent tank 12. It is reduced to 1-aminoanthraquinone using a suitable reaction temperature. The resulting reaction mixture was filtered through filter 1.
3, and the crystals of 1-7 minoanthraquinone are stored in a product tank 15. The furnace liquid is stored in a waste liquid tank 14 and treated as appropriate.

[Examples] Next, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples.

Example-1 In electrolytic cell 2, the anode is PT-plated TiW electrode and the cathode is 5U.
Using a S316L electrode and a fluorine-based cation exchange membrane (manufactured by DuPont, Nafion 423) as a diaphragm, the current density was 15A.
Cerium ammonium nitrate - 2 mol/l at /dm
A nitric acid aqueous solution was electrolyzed to obtain an anolyte having a ceric ion concentration of 2.4 mol/l relative to 2 mol/l of a nitric acid aqueous solution. The catholyte was a 2 mol/l nitric acid aqueous solution. Current efficiency was 95%. 3954 Ky of nitric acid aqueous solution containing this ceric ion and 300 kg of t-butylbenzene
100 kg of 1-nitronaphthalene dissolved in 45
The crystals obtained by internally irradiating ultrasonic waves of 732 KHz and 1400 W at ℃ and reacting with stirring in the liquid phase oxidation reactor 5 for about 1 hour are separated in the filter 7, and the organic layer and the aqueous layer are separated from the furnace liquid. After separation in the separation column 8, the right nWI was sent to the solvent tank 6 for circulation and reuse, and the aqueous layer was sent to the anode tank 3 for electrolytic regeneration of cerium ions produced after the reaction. On the other hand, the crystals are introduced into the Diels-Alder reactor after washing, but the weight of the crystals after washing is 102.1y, and when this crystal is analyzed by gas chromatography, it is found that pure If
It was confirmed that it was 99.5% 5-nitro-1,4-naphthoquinone.

Next, in the reactor 9, the 5-nitronaphthoquinone 102.
After adding about 300 Ky of methanol and 68.3 Kg of 1,3-butadiene, 3 K! J/ctn
The reaction was carried out under pressure at 90° C. for 2.5 hours. The crystals and reaction solution after the reaction were transferred to reactor 11, 157.8 kg of 30% sodium hydrogen sulfide aqueous solution was added thereto, and the mixture was heated at 90°C under normal pressure.
When the reaction was carried out for 2 hours, red crystals were obtained.

The crystal size after furnace separation, washing and drying is 108.3/(
It was g. When the obtained product was analyzed by gas chromatography and infrared spectroscopy, it was confirmed that it was 1-aminoanthraquinone with a purity of 99.0%. Therefore,
The yield of pure 1-aminoanthraquinone is 107.2wt%
Met.

Example-2 Reaction in liquid phase oxidation reactor 5 without ultrasonic irradiation
Post-reaction treatment and analysis were carried out in the same manner as in Example-1, except that the reaction was carried out at 0°C for about 2 hours. As a result, 101.2 kg of 5-nitronaphthoquinone was obtained. Next, about 3 methanol
00 Ky, 1,3-butadiene 67.3 K9 was added and reacted in the same manner as in Example-1, and in the next step, 30% aqueous sodium hydrogen sulfide solution was added at 15.5. The same post-reaction treatment was performed except that Ell was added. As a result, after furnace separation, washing, and drying, 107.0 Kylli of 1-aminoanthraquinone with a purity of 98.7% was obtained. Therefore, the yield of pure 1-aminoanthraquinone is 105.6 wt%
Met.

[Effects of the Invention] By carrying out the present invention as described above, 5-nitro-1,4-naphthoquinone with few by-products is produced in the liquid phase oxidation reaction step of 1-nitronaphthalene. Even in the Diels-Alder reaction and reduction reaction with 1,3-butadiene, highly pure 1-aminoanthraquinone does not require complicated purification steps and is beneficial in terms of working environment and pollution, with high yield and high selectivity. can be manufactured.

Patent applicant: Nippon Shokubai Chemical Co., Ltd. Ko l# ] 1. Yin (6 liquid rank 2. Electrolytic cell 3. Positive T4i liquid tank 4.1-Nitronaphthalene tank 5. Liquid (mouth Mization reactor) 6. Solvent tank 7. Filter 8. Separation 1jj 9. Diels-Alder reactor 10.1.3-Butadiene tank 11.i! ! Original reactor 12, Reduced rIII tank 13. Filter 14. Waste liquid tank

Claims (3)

[Claims] (1) A) A step of oxidizing 1-nitronaphthalene in a liquid phase using an acidic aqueous solution containing ceric ions. b) From the reaction mixture obtained in step b), 5-nitro-
A step of separating crystals containing 1,4-naphthoquinone from an acidic aqueous solution containing cerium ions. c) 5-nitro-1,4-naphthoquinone obtained in step b) is subjected to a Diels-Alder reaction with 1,3-butadiene to obtain crystals containing 5-nitro-1,4,4a,9a-tetrahydroanthraquinone. The process of analysis and separation. d) 5-nitro-1,4,4a obtained in step c),
A step of reducing 9a-tetrahydroanthraquinone using a reducing agent and then separating and purifying crystals containing 1-aminoanthraquinone. e) Electrolytically oxidize an acidic aqueous solution containing cerous ions as an anolyte, an electrolyte as a catholyte, and an ion exchange membrane as a diaphragm, and oxidize cerous ions in the acidic aqueous solution to ceric ions. The process of sending the product to step (a). A method for producing 1-aminoanthraquinone, characterized by comprising: The method according to claim (1), characterized in that in step (2) a), 1-nitronaphthalene is oxidized in a liquid phase under ultrasonic irradiation. (3) The acid concentration in the acidic aqueous solution containing ceric ions in step (a) is 0.3 to 10 mol/l, according to claim (1) or (2). Method.