JP2001354633A - Method for producing 2,5-diaminohydroquinone and/or its ester or their salts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and inexpensively produce 2 5-diamino-hydroquinone and/or its ether or their salts useful as a monomer for a heat-resistant polymer polybenzoxazole(PBO) and a dye intermediate by one process. SOLUTION: This method for producing 2,5-diamino-hydroquinone of general formula (3) and/or its ether or their salts comprises reducing a 2-alkoxy-4- nitroaniline and/or 2-hydroxy-4-nitroaniline of general formula (1) in which the para-position of OR1 group is nonsubstituted with a reducing agent in a reaction solvent, then, without isolation, to give a reaction intermediate of general formula (2) (R1 and R2 are each hydrogen or a 1-4C alkyl; R3 is a 1-4C alkyl; the para-position of OR1 is nonsubstituted; X and Y are each hydrogen or a 1-4C alkyl; during the reaction process, not necessarily X is R1 and Y is R2; n is an integer of 0, 1 or 2) and carrying out a rearrangement reaction by heat and/or an acid catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing 2,5 diaminohydroquinone (DAHQ) and / or an ether or a salt thereof. More specifically, dye intermediates and heat-resistant polymer polybenzoxazole (PBO)
The present invention relates to a method for easily and inexpensively producing 2,5 diaminohydroquinone and / or its ether and derivatives thereof, which are useful as a monomer of the above. PBO has not only heat resistance but also strength, elastic modulus, flame retardancy, chemical resistance, etc.
It is known as a superfiber (trade name “Zylon”) raw material that exceeds conventional fibers.

[0002]

2. Description of the Related Art Hitherto, as a method for producing 2,5-diaminohydroquinone and / or its ether or a salt thereof, for example, in the case of 2,5-diaminohydroquinone,
(1) 2,5-diamino-p-benzoquinone in concentrated hydrochloric acid,
Direct reduction with stannous chloride (Wolf et al., Journal of Polymer Science, Part A, 6,1503)
(1968) and Beilstein Organic Chemistry, 1
3,791) and (2) a method of reducing 2,5-diamino-3,6-dihalo p-benzoquinone using a noble metal catalyst such as palladium / carbon and simultaneously dehalogenating to reduce to 2,5 diamino-p-hydroquinone. (JP-B-3-38262) is known.

However, the starting materials used in these methods, such as 2,5-diamino-p-benzoquinone and its halogen-substituted product, require several stages of reaction operations until they are obtained, and are expensive. In addition, isolation and purification operations are required in each step due to the generation of by-products and isomers, and there is a problem that the yield is greatly reduced.

On the other hand, a reaction referred to as quinol rearrangement or Bamberger rearrangement in which a substituted nitro group of a nitrated aromatic compound is reduced to a hydroxyamino group and subsequently rearranged with an acid catalyst or the like to obtain an aminophenol is known. It is. For example, US Pat. No. 2,765,342, 37
No. 15397 describes a method for selectively obtaining p-aminophenol from nitrobenzenes. However, it is clear that these methods are not intended for the production of 2,5-diaminohydroquinone and / or its ether having a unique structure of having two o-aminophenols in the same molecule. .

Japanese Patent Application Laid-Open No. 8-283216 discloses a method for obtaining 1,3-diamino-4,6-dialkoxybenzene from 1-alkoxy-2,4-dinitrobenzene by the same reductive rearrangement reaction. JP-A-11-49732 also describes a method for obtaining 1,3-diamino-4,6-dihydroxybenzene from 1,3-dinitrobenzene by the same reductive rearrangement reaction. Although these methods do not disclose a method for producing 2,5-diaminohydroquinone and / or an ether thereof, diaminoresorcinol and an ether thereof produced by these methods are not disclosed.
It has an isomer relationship with 5-diaminohydroquinone and / or its ether, and is similarly useful as a dye intermediate or a monomer of heat-resistant high-molecular-weight polybenzoxazole (PBO).

The problems of these methods are listed for reference. The method disclosed in Japanese Patent Application Laid-Open No. H11-49732 goes through two-stage rearrangement, but the reaction yield of the second stage is low, and it is not an industrial production method. I can't get it. Japanese Patent Application Laid-Open No. 8-283216 is a simple method, but also involves reduction of two nitro groups and requires a strong reduction, so that the progress of the rearrangement reaction is also difficult. That is, both methods for reducing and rearranging two nitro groups have problems in the rearrangement step.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems relating to the production of 2,5 diaminohydroquinone and / or an ether or a salt thereof, and provides a high-quality 2,5 diamino-hydroquinone. An object of the present invention is to provide a method for producing hydroquinone and / or its ether or a salt thereof easily and inexpensively.

[0008]

Means for Solving the Problems In order to solve these problems, the present inventors have intensively studied methods for producing 2,5 diaminohydroquinone and / or an ether or a salt thereof, which are industrially advantageous. As a result, 2-alkoxy-4 containing one nitro group can be industrially supplied at low cost.
-Nitroaniline and / or 2-hydroxy-4-nitroaniline as a new raw material, and 2,5 diaminohydroquinone and / or
Alternatively, the present inventors have found a method for producing the ether or a salt thereof, and have completed the present invention.

That is, the present invention includes the following inventions. The 2-alkoxy-4-nitroaniline and / or 2-hydroxy-4-nitroaniline represented by the general formula (1), which is unsubstituted at the para-position of the OR1 group, is reduced with a reducing agent in a reaction medium, and is represented by the general formula (2). After obtaining the reaction intermediate to be carried out, a 2,5 diaminohydroquinone represented by the general formula (3) and / or an ether or a salt thereof is produced by performing a heat and / or acid catalyzed rearrangement reaction. how to.

[0010]

Embedded image

[0011]

Embedded image

[0012]

Embedded image

In the above formula, R1 and R2 are each hydrogen or alkyl having 1 to 4 carbons, and R3 is alkyl having 1 to 4 carbons, provided that the para position of the OR1 group is unsubstituted. X and Y are each hydrogen or alkyl having 1 to 4 carbon atoms, and are not necessarily X = R1 and Y = R2 during the reaction step. n is an integer of 0, 1 or 2.

More specifically, the above-mentioned method for carrying out a rearrangement reaction without isolating a reaction intermediate obtained by reduction, wherein the reaction medium is an alcohol having 1 to 4 carbon atoms and / or water. The method as described above, wherein the reducing agent is at least one selected from hydrogen, hydrazine, hypophosphorous acid, platinum, palladium, rhodium, ruthenium, Raney nickel, stannous chloride, and the reaction medium is an aqueous inorganic electrolyte solution. And an organic solvent which dissolves 2-alkoxy-4-nitroaniline and / or 2-hydroxy-4-nitroaniline and is inert to all the reagents under the reaction conditions, wherein the reducing agent comprises zinc, iron or tin. The above-mentioned method, wherein at least one metal selected from the group is used, the above-mentioned method, wherein the reaction temperature at the time of reduction does not exceed 25 ° C. Wherein the amount of is 2 to 5 times the molar amount of 2-alkoxy-4-nitroaniline and / or 2-hydroxy-4-nitroaniline, wherein the acid catalyst for the rearrangement reaction is selected from the group consisting of sulfuric acid, methanesulfonic acid, and trifluoroacetic acid. In the method according to any one of the above, and in formulas (1), (2) and (3), R1 and R2 are each hydrogen or a methyl group, and X and Y are each a hydrogen or methyl group. And n
Is 0. The method according to any of the above, wherein

A method for directly producing 2,5 diaminohydroquinone and / or its ether or a salt thereof by a two-step reaction of reduction and subsequent rearrangement of 2-alkoxy-4-nitroaniline and / or 2-hydroxy-4-nitroaniline is as follows. , Had never been found before.

Hereinafter, the present invention will be described specifically. The reduction of 2-alkoxy-4-nitroaniline and / or 2-hydroxy-4-nitroaniline, which is the first step of the present invention, is carried out in a reaction medium using a reducing agent. Suitable raw materials include 2-alkoxy-4-nitroaniline and / or 2-substituted unsubstituted or substituted with one or two alkyl groups, but unsubstituted in the para position with respect to the OR1 group in the general formula (1). Hydroxy-4-nitroaniline, and the general formula (1) is

[0017]

Embedded image

In the above formula, R1 is hydrogen or alkyl having 1 to 4 carbons, R3 is alkyl having 1 to 4 carbons,
However, the para position of the OR1 group is unsubstituted. n is 0, 1
Or an integer of 2. It corresponds to the one represented by.

Specifically, 2-hydroxy-4-nitroaniline, 2-hydroxy-3-methyl-4-nitroaniline, 2-hydroxy-6-methyl-4-nitroaniline, 2-methoxy-4-nitroaniline, 2-ethoxy-4-nitroaniline, 2-propoxy-4-nitroaniline, 2-butoxy-4-nitroaniline, 2-methoxy-3-methylaniline 4-nitroaniline, 2-methoxy-6-methyl-4-nitroaniline, 2-ethoxy-3
-Methyl-4-nitroaniline, 2-ethoxy-6-methyl-4-nitroaniline and the like. Preferred are 2-hydroxy-4-nitroaniline and 2-methoxy-4-nitroaniline.

The reaction medium used may be an alcohol and / or water having 1 to 4 carbon atoms, or an aqueous solution of an inorganic electrolyte to which ammonium chloride, potassium chloride or the like is added.
A mixture with an organic solvent which dissolves the alkoxy-4-nitroaniline and / or 2-hydroxy-4-nitroaniline is used. The mixture may be a heterogeneous system composed of two or more layers or a homogeneous system. Specific examples of the alcohol include methanol, ethanol, propanol, isopropanol and butanol. As the organic solvent, a solvent containing at least one selected from the group consisting of ether-based, ester-based, ketone-based, carboxylic acid-based, and halogenated hydrocarbon-based organic solvents is used. Specifically, diethyl ether, diisopropyl ether,
Tetrahydrofuran, dioxane, ethyl acetate, propyl acetate, butyl acetate, acetone, methyl ethyl ketone,
Examples thereof include methyl isobutyl ketone, acetic acid, dichloromethane, chloroform, dichloroethane, and tricrene. Preferred are tetrahydrofuran, methanol, ethanol and dichloromethane.

The amount of the reaction medium is appropriately determined by the practitioner, but is generally about 2-alkoxy-4-nitroaniline and / or 2-hydroxy-4-nitroaniline.
1 to 50 parts by weight, preferably 10 to 40 parts by weight based on parts by weight
Parts by weight. When an inorganic electrolyte is used, its addition amount is 2-alkoxy-4-nitroaniline and / or 2-alkoxy-4-nitroaniline.
The molar amount is 1 to 10 times, preferably 2 to 6 times the molar amount of hydroxy-4-nitroaniline. If it is less than 1 fold, the reduction will not proceed sufficiently, and if it is more than 6 fold the reaction will proceed, but the economic loss will increase.

In the reduction reaction of the present invention, the resulting reaction intermediate is further reduced to form a super-reduced product such as 2-alkoxy-4-aminoaniline and / or 2-hydroxy-4-aminoaniline or an azobenzene compound. Need to be well controlled. The present inventors diligently studied this point and found that it is important to control the type of the reducing agent, the reaction temperature, and the equivalent ratio of the reducing agent.

As the reducing agent, the reaction medium is an aqueous solution of an inorganic electrolyte and an organic solvent which dissolves 2-alkoxy-4-nitroaniline and / or 2-hydroxy-4-nitroaniline and is inert to all reagents under the reaction conditions. If a mixture, it is a metal powder such as zinc, iron, tin. When the reaction medium is an alcohol having 1 to 4 carbon atoms and / or water, known reducing agents can be widely used, but Raney nickel, stannous chloride,
Examples include at least one selected from palladium, platinum, rhodium, ruthenium, hydrogen, hydrazine, and hypophosphorous acid. Noble metals such as palladium and platinum act as catalysts, and those supported on a carrier such as carbon, alumina, silica and zeolite are preferably used. Among these reducing agents, zinc powder is preferable from the viewpoint of reactivity, economy and ease of handling.

In the case of zinc powder, the amount is preferably 2 to 5 times the molar amount of 2-alkoxy-4-nitroaniline and / or 2-hydroxy-4-nitroaniline in order to allow the reduction to proceed completely while suppressing overreduction. Is in the range of 2.5 to 3.5 moles. If it is less than 2 times, the reduction does not proceed sufficiently, and if it is more than 5 times, the produced reaction intermediate is further reduced, and a large amount of overreduced products such as 2-alkoxy-4-aminoaniline and / or 2-hydroxy-4-aminoaniline are produced. There is a tendency.

When the reducing agent is a metal powder such as zinc, the reducing agent is added gradually to enhance the stirring intensity to promote the reduction reaction. If all of the predetermined amount is added at once in the early stage of the reaction, overheating occurs, and the yield of the product is reduced by a side reaction.

In general, the reaction temperature is kept as low as possible in order to suppress the formation of colored matter due to side reactions, and it is desirable that the reaction be completed in a short time by vigorous stirring while maintaining the temperature at 20 ° C. or less. More preferably 5 ° C
It is kept below.

In the present invention, at least one selected from phosphines, phosphites, sulfoxides, and heterocyclic nitrogen compounds known in the art for suppressing side reactions such as formation of a super-reductant is used. It can be used as an inhibitor. Specific examples include triphenylphosphine, triethylphosphine, trioctylphosphine, triphenylphosphite, piperidine, pyrrole, quinoline, pyridine and dimethylsulfoxide. Preferably dimethyl sulfoxide,
Triphenylphosphine.

The progress of the reaction can be confirmed by means such as high performance liquid chromatography and thin layer chromatography. The reaction is preferably performed in a nitrogen atmosphere in order to avoid oxidation of the product.

After the reduction reaction is completed, the reaction medium containing the produced reaction intermediate, and the solid reducing agent and its oxide are separated into solid and liquid by a technique such as filtration. Since the product is often unstable, it is desirable to carry out the reaction quickly under an inert atmosphere such as nitrogen.

The reaction intermediate obtained after the reduction reaction has the general formula (2)

[0031]

Embedded image

In the above formula, R1 and R2 are hydrogen or a compound having 1 to 1 carbon atoms.
And R3 is alkyl having 1 to 4 carbons, provided that the para-position of the OR1 group is unsubstituted. n is an integer of 0, 1 or 2. It corresponds to the one represented by.

The rearrangement of the reaction intermediate, which is the second step of the present invention, is carried out in a reaction medium by heating and / or using an acid catalyst. Preferably, without isolating and purifying the reaction intermediate obtained in the previous reduction reaction, subsequent rearrangement reaction is carried out in a solution subjected to solid-liquid separation, whereby the desired 2,5 diamino- It is possible to obtain hydroquinone and / or its ether. At this time, when the reaction medium is a mixed system composed of two or more layers, the organic layer is separated, and the rearrangement reaction is continuously performed in the aqueous layer containing the reaction intermediate. The organic layer can be recycled as it is for the reduction reaction.

The acid catalyst is not particularly limited as long as it is generally used, but among them, sulfuric acid, methanesulfonic acid, trifluoroacetic acid and the like are preferable. These may be used in combination. Of these, sulfuric acid is more preferred. The amount is from 10 to 150 times, preferably from 20 to 120 times, that of 2-alkoxy-4-nitroaniline and / or 2-hydroxy-4-nitroaniline. If the molar ratio is less than 10 times, the rearrangement does not proceed sufficiently. If the molar ratio is 150 times or more, the reaction temperature is not particularly limited, but is set by the practitioner so that the reaction proceeds under heating and reflux conditions. The reaction time is usually about 0.5 to 2 hours.

The 2,5 diamino-hydroquinone and / or its ether obtained after completion of the rearrangement reaction is represented by the general formula (3)

[0036]

Embedded image

In the above formula, R1 and R2 are hydrogen or a compound having 1 to 1 carbon atoms.
And R3 is an alkyl having 1 to 4 carbons, provided that the para-position of the OR1 group is unsubstituted. X,
Y is hydrogen or alkyl having 1 to 4 carbons,
n is an integer of 0, 1 or 2. It corresponds to the one represented by.

Specifically, 2,5 diaminohydroquinone, 2,5-diamino-3-methylhydroquinone, 2,
5-diamino-3-methylhydroquinone, 2,5-diamino-4-methoxyphenol, 2,5-diamino-4
-Ethoxyphenol, 2,5 diamino-4-propoxyphenol, 2,5 diamino-4-butoxyphenol, 2,5 diamino-4-methoxyphenol methyl ether, 2,5 diamino-4-ethoxyphenol methyl ether, 2,5 diamino-4- Propoxyphenol methyl ether, 2,5 diamino-4-butoxyphenol methyl ether, 2,5 diamino-4-methoxyphenol ethyl ether, 2,5 diamino-4-ethoxyphenol ethyl ether, 2,
5-diamino-4-propoxyphenol ethyl ether and 2,5 diamino-4-butoxyphenol ethyl ether. Preferred are 2,5 diaminohydroquinone, 2,5 diamino-4-methoxyphenol and 2,5 diamino-4-methoxyphenol methyl ether.

The target compound, 2,5 diamino-hydroquinone and / or its ether, is relatively unstable such as being decomposed by light when isolated in a neutral state and being oxidized by air. It is preferred to isolate in the form of an amine salt. Examples of the strong acid include hydrochloric acid, hydrobromic acid, hydroiodic acid, phosphoric acid, sulfuric acid, methanesulfonic acid, and trifluoroacetic acid. Of these, hydrochloric acid and phosphoric acid are preferred from the viewpoint of handling during polymerization. In general, the precipitated amine salt can be recovered by adding a sufficient amount of a strong acid to the reaction medium, either neat or as a solution. In the case of hydrochloric acid, hydrogen chloride may be directly blown. It is preferable to use an antioxidant such as stannous chloride at the time of isolation. If necessary, activated carbon can be used.

The present invention will be specifically described below, but the present invention is not limited to these examples.

[0041]

EXAMPLES Example 1 15 parts by weight of 2-hydroxy-4-nitroaniline (HNA) was placed in a four-necked flask equipped with a stirrer, a nitrogen inlet tube, and a thermometer and dissolved in 130 parts by weight of tetrahydrofuran. When a solution prepared by dissolving 25 parts by weight of ammonium chloride in 150 parts by weight of water was added thereto, they were separated into two layers. With vigorous stirring in an ice bath, 23 parts by weight of zinc powder were carefully added little by little so that the liquid temperature did not exceed 5 ° C. The addition was made over 15 minutes and stirring was continued for another 30 minutes. After the completion of the reaction, the solution became slightly yellowish and homogeneous, and the solid was immediately filtered under reduced pressure, and the solid was washed with a small amount of water and tetrahydrofuran. The filtrate and the washing solution were combined, and THF was distilled off under reduced pressure. In the high performance liquid chromatography analysis (reverse phase mode) of the obtained solution, 2-hydroxy-4-nitroaniline was completely reacted and disappeared. The solution was transferred to an Erlenmeyer flask, and 80 parts by weight of concentrated sulfuric acid was added. After the atmosphere was replaced with nitrogen, the mixture was heated to reflux for 1 hour while stirring under a nitrogen stream. The solution became light brown. This was allowed to cool at room temperature, and further neutralized with an aqueous sodium hydroxide solution under ice cooling. Further, 1 part by weight of stannous chloride, 100 parts by weight of concentrated hydrochloric acid and 5 parts by weight of powdered activated carbon were added with stirring, and the mixture was heated at 50 ° C. until the deposited precipitate was dissolved. After filtering the activated carbon through a fluted filter paper, concentrated hydrochloric acid was added and the mixture was allowed to cool to room temperature, and the precipitated white powder crystals were filtered. Wash with diluted hydrochloric acid,
The white powder obtained by drying over phosphoric anhydride was 2,5-diaminohydroquinone dihydrochloride from the comparison with a nuclear magnetic resonance absorption spectrum, an infrared absorption spectrum, and a standard product for mass spectrometry. The theoretical yield from 4-nitroaniline was 53%.

(Examples 2, 3, and 4)
The same operation as in Example 1 was performed except that the reduction reaction temperature, the reducing agent molar ratio, and the type of acid catalyst were changed as shown in (1).
The results are also shown in Table 1.

Example 5 16 parts by weight of 2-methoxy-4-nitroaniline was placed in a four-necked flask equipped with a stirrer, a nitrogen inlet tube, and a thermometer and dissolved in 130 parts by weight of methanol / tetrahydrofuran. To this, 0.2 part by weight of Raney nickel was added, and 12 parts by weight of hydrazine monohydrate was carefully added little by little while stirring vigorously in an ice bath so that the liquid temperature did not exceed 10 ° C. The addition was made over 15 minutes and stirring was continued for another 30 minutes. After the reaction,
Immediately, the solid was filtered under reduced pressure, and the solid was washed with a small amount of tetrahydrofuran. The filtrate and the washing solution were combined, transferred to an Erlenmeyer flask, 80 parts by weight of concentrated sulfuric acid was added, the atmosphere was replaced with nitrogen, and the mixture was heated to reflux for 1 hour while stirring under a nitrogen stream. When the reaction solution was analyzed by high performance liquid chromatography analysis (reverse phase mode), 2,5-diaminohydroquinone dimethyl ether and 2,5-diamino-4-methoxyphenol were obtained in 43% and 15% yield, respectively.

Example 6 In an autoclave, 16 parts by weight of 2-methoxy-4-nitroaniline was dissolved in 150 parts by weight of methanol. 5% platinum / carbon
5 parts by weight and 4 parts by weight of dimethyl sulfoxide were added, and after sealing, the mixture was stirred at a hydrogen pressure of 2 kg / cm 2 at 30 to 50 ° C. for 3 hours. Immediately after the completion of the reaction, the solid was filtered under reduced pressure, and the solid was washed with a small amount of methanol. The filtrate and the washing solution were combined, transferred to an Erlenmeyer flask, 80 parts by weight of concentrated sulfuric acid was added, the atmosphere was replaced with nitrogen, and the mixture was heated to reflux for 1 hour while stirring under a nitrogen stream. When the reaction solution was analyzed by high performance liquid chromatography analysis (reverse phase mode), 2,5-diaminohydroquinone dimethyl ether and 2,5-diamino-4-methoxyphenol were obtained in yields of 55% and 12%, respectively.

(Comparative Example 1) A reaction was carried out in the same manner as in Example 1 except that the reduction reaction was carried out in the range of 28 ° C to 61 ° C without controlling the temperature. An oily component was found which was colored and insoluble in the reaction medium. When the reaction solution was analyzed by high performance liquid chromatography, the yield of the desired 2,5-diaminohydroquinone was about 2%. The results are shown in Table 1.

Comparative Example 2 The reaction was carried out in the same manner as in Example 1 except that the amount of the reducing agent was changed at the molar ratio shown in Table 1. As a result, the reduction did not proceed sufficiently and the raw materials remained. The results are shown in Table 1.

[0047]

[Table 1]

The yield was determined by high performance liquid chromatography (eluent acetonitrile / tetrahydrofuran / water / phosphoric acid =
1.5 / 4.5 / 100 / 0.23 (EDTA4Na:
45 ppm), UV (280 nm), flow rate 1 ml / mi
Quantified by the internal standard method in n).

[0049]

According to the present invention, 2,5-diamino-hydroquinone and / or its ether or a salt thereof, which is useful as a heat-resistant high-molecular-weight polybenzoxazole (PBO) monomer or dye intermediate in one step, is prepared. It can be manufactured simply and inexpensively. In addition, PBO fibers having high strength and high elastic modulus, and high heat-resistant PBO fibers are obtained from PBO obtained by polymerizing this.
It becomes possible to provide a BO film or the like at low cost.

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 4H006 AA02 AC52 BA07 BA11 BA19 BA21 BA23 BA24 BA25 BA26 BA35 BA66 BA70 BB14 BB31 BE20 BE27 BJ50 BN30 BP30 BU46 4H039 CA71 CB40 CD10 CD20 CD40 CJ10

Claims (8)

[Claims] (1) reducing a 2-alkoxy-4-nitroaniline and / or 2-hydroxy-4-nitroaniline represented by the general formula (1), wherein the para-position of the OR1 group is unsubstituted, with a reducing agent in a reaction medium; After the reaction intermediate represented by (2) is obtained, a rearrangement reaction using a heat and / or an acid catalyst is carried out, whereby 2, 5 represented by the general formula (3) is obtained.
A method for producing diaminohydroquinone and / or an ether or a salt thereof. Embedded image Embedded image Embedded image In the above formula, R1 and R2 are each hydrogen or alkyl having 1 to 4 carbons, and R3 is alkyl having 1 to 4 carbons, provided that the para position of the OR1 group is unsubstituted. X, Y
Is hydrogen or alkyl having 1 to 4 carbon atoms, and is not necessarily X = R1 and Y = R2 during the reaction step. n is an integer of 0, 1 or 2. 2. The method according to claim 1, wherein the rearrangement reaction is carried out without isolating the reaction intermediate obtained by the reduction. 3. The reaction medium is an alcohol having 1 to 4 carbon atoms and / or water, and the reducing agent is hydrogen, hydrazine, hypophosphorous acid, platinum, palladium, rhodium, ruthenium, Raney nickel, stannous chloride. 3. The method according to claim 1, wherein the method is at least one selected from the group consisting of: 4. The reaction medium is a mixture of an aqueous inorganic electrolyte solution and an organic solvent which dissolves 2-alkoxy-4-nitroaniline and / or 2-hydroxy-4-nitroaniline and is inert to all reagents under the reaction conditions. Yes,
3. The method according to claim 1, wherein the reducing agent is at least one metal selected from the group consisting of zinc, iron and tin. 5. The process according to claim 4, wherein the reaction temperature during the reduction does not exceed 25 ° C. 6. The method according to claim 5, wherein the amount of the reducing agent is 2 to 5 times the molar amount of 2-alkoxy-4-nitroaniline and / or 2-hydroxy-4-nitroaniline. 7. The method according to claim 1, wherein the acid catalyst for the rearrangement reaction is at least one selected from the group consisting of sulfuric acid, methanesulfonic acid, and trifluoroacetic acid. 8. In the general formulas (1), (2) and (3), R1 and R2 are each hydrogen or a methyl group;
8. The method according to claim 1, wherein Y is hydrogen or a methyl group, and n is 0.