A method for preparing aromatic amine compounds

Abstract

The present invention discloses a method for preparing aromatic amine compounds. The aromatic nitro compound is dissolved in an organic solvent, and the corresponding aromatic amine compound is obtained through a catalytic reduction reaction. The reducing agent is hydrazine hydrate, and the catalyst adopts a hydrogenase mimic. The method of the present invention avoids the use of precious metals through the catalysis of the hydrogenase mimic, and does not require high temperature and high pressure conditions. The reaction conditions are mild. The aromatic amine compound is synthesized by a one-step method, with simple operation and high reaction yield, which is suitable for the preparation of aromatic amine compounds and has the value of industrial popularization and application.

Description

Technical Field

[0001] The present invention belongs to the field of organic synthesis, relates to a method for preparing aromatic amine compounds, and particularly relates to a method for preparing aromatic amine compounds by reducing nitro compounds. Background Art

[0002] Aromatic amine compounds generally refer to amine compounds with aromatic substituents, that is, the amino group is connected to an aromatic ring, and they widely exist in natural products. Aromatic amine compounds are widely used as important chemical raw materials and pharmaceutical intermediates in the fields of chemical drugs, dyes, flame retardants, polymer functional materials, etc. Especially in the pharmaceutical field, such as paracetamol for antipyretic and analgesic, benzocaine and tetracaine hydrochloride for anesthesia, and bicalutamide for treating prostate cancer. With the increasing importance and demand of aromatic amine compounds, the preparation of such compounds has received great attention. At present, aromatic amine compounds are commonly prepared by reducing nitro compounds in an acidic medium. Commonly used reducing agents include iron, zinc, tin, copper, etc., and sodium borohydride and hydrazine hydrate are also often used as reducing agents, or hydrogen is used as a reducing agent (generally requiring catalysts and high temperature and high pressure conditions), and finally the goal of reducing nitro compounds to prepare aromatic amine compounds is achieved.

[0003] In the process of implementing the present invention, the inventors found that there is at least one of the following technical problems in the prior art:

[0004] a) Require precious metals and high temperature and high pressure conditions, and the reaction conditions are relatively harsh;

[0005] b) The reaction operation is relatively complex;

[0006] c) Toxic by-products may be generated during the reaction process;

[0007] d) The reaction yield is not high;

[0008] e) The reaction purification is difficult.

[0009] Based on this, developing a new method for green and efficient preparation of aromatic amine compounds is of great significance for promoting industrial development. Summary of the Invention

[0010] In view of this, the purpose of the present invention is to provide a new method for green and efficient preparation of aromatic amine compounds.

[0011] Through long-term exploration, experimentation, and numerous attempts, as well as continuous reform and innovation, in order to solve the above technical problems, the technical solution provided by the present invention is to provide a method for preparing aromatic amine compounds. The aromatic nitro compound is dissolved in an organic solvent, and the corresponding aromatic amine compound is obtained through a catalytic reduction reaction. The reducing agent is hydrazine hydrate, and the catalyst is a hydrogenase mimic.

[0012] According to an embodiment of the method for preparing aromatic amine compounds of the present invention, the hydrogenase mimic is an organoiron complex or a carbonyl iron complex.

[0013] According to an embodiment of the method for preparing aromatic amine compounds of the present invention, the hydrogenase mimic is Fe2(SCH2)2(CO)6, and the molar amount of the catalyst is 5-10% of the molar amount of the aromatic nitro compound.

[0014] According to an embodiment of the method for preparing aromatic amine compounds of the present invention, the organic solvent is ethanol, and the concentration of the aromatic nitro compound in the ethanol solution is 0.08-0.1 mol / L.

[0015] According to an embodiment of the method for preparing aromatic amine compounds of the present invention, the molar ratio of the reducing agent to the aromatic nitro compound is 10-11:1.

[0016] According to an embodiment of the method for preparing aromatic amine compounds of the present invention, the reaction temperature of the catalytic reduction reaction is 75-85 °C, and the reaction time is 24-48 h.

[0017] According to an embodiment of the method for preparing aromatic amine compounds of the present invention, the structural formula of the aromatic nitro compound is shown as Formula I:

[0018]

[0019] In Formula I, the R1 group is a group with weaker oxidizing property than nitro or nitro; a substituent or nitro that is not reduced or is reduced later than nitro;

[0020] The aromatic amine compound is shown as Formula II:

[0021]

[0022] In Formula II, the R2 group is a group with weaker oxidizing property than nitro or amino. When R1 is nitro, R2 is amino; when R1 is a substituent other than nitro, R2 is the same as R1.

[0023] According to an embodiment of the method for preparing aromatic amine compounds of the present invention, the R1 group includes any one of methyl, alkyl, alkenyl, halogenated group, nitro group, amino group, ether group, hydroxyl group, carbonyl group, carboxyl group, sulfhydryl group, and amine salt group.

[0024] According to an embodiment of the method for preparing aromatic amine compounds of the present invention, the R1 group is located at one or more of the ortho, meta, and para positions of the nitro group.

[0025] According to an embodiment of the method for preparing aromatic amine compounds of the present invention, the aromatic nitro compound is:

[0026] A. p-Nitroanisole, used for preparing methoxyaniline;

[0027] B. 4-Nitrobromobenzene, used for preparing p-bromoaniline;

[0028] C. 4-Nitroiodobenzene, used for preparing p-iodoaniline;

[0029] D. 2-Nitroaniline, used for preparing o-phenylenediamine;

[0030] E. 3-Nitroaniline, used for preparing m-phenylenediamine;

[0031] F. 2-Nitrophenol, used for preparing o-aminophenol;

[0032] G. 3-Nitrobenzyl alcohol, used for preparing 3-aminobenzyl alcohol.

[0033] Compared with the prior art, one of the above technical solutions has the following advantages:

[0034] a) The method of the present invention uses a hydrogenase mimic for catalysis, avoiding the use of precious metals and not requiring high-temperature and high-pressure conditions. The reaction conditions are mild. The aromatic amine compounds are synthesized by a one-step method, with simple operation and high reaction yield, which is suitable for the preparation of aromatic amine compounds and has the value of industrial promotion and application.

[0035] b) After the reaction is completed, the aromatic amine compounds can be separated by conventional column chromatography or thin-layer chromatography analysis. The organic solvent used for separation is a mixed solvent of petroleum ether and ethyl acetate.

[0036] c) In an embodiment of the method of the present invention, the catalyst is Fe2(SCH2)2(CO)6, which is an organoiron complex with the chemical name of iron dithiocarboxylate dicarbonyl. This compound consists of two iron atoms and six carbonyl groups.

[0037] d) After the reaction is completed, the aromatic amine compounds can be separated by conventional column chromatography or thin-layer chromatography analysis. The organic solvent used for separation is a mixed solvent of petroleum ether and ethyl acetate.

[0038] c) In an embodiment of the method of the present invention, the catalyst is Fe2(SCH2)2(CO)6, which is an organoiron complex. Its chemical name is iron dithiocarboxylate dicarbonyl. This compound consists of two iron atoms and six carbonyl groups.

[0039] d) After the reaction is completed, the aromatic amine compounds can be separated by conventional column chromatography or thin-layer chromatography analysis. The organic solvent used for separation is a mixed solvent of petroleum ether and ethyl acetate.

[0040] It consists of (CO) and two thioethyl (SCH2) ligands. The thioethyl ligand is formed by connecting a sulfur atom with an ethyl group (-CH2CH2-). The carbonyl ligand is composed of a carbon atom and an oxygen atom, and coordinates with the iron atom through a double bond. This organoiron complex has specific structures and chemical properties. The inventors have proven through experiments that this compound can be used in the catalytic reduction reaction of nitro compounds to prepare aromatic amine compounds, and the highest yield can reach 99%. In multiple experimental cases, under the same other reaction conditions, without adding the catalyst hydrogenase mimic Fe2(SCH2)2(CO)6, the yields of the reactions did not reach 10%. At the same time, the inventors have also proven that not all organoiron complexes can be used in the catalytic reduction reaction of nitro compounds to prepare aromatic amine compounds. For example, under the same other reaction conditions, when [Fe2(SCH2CH2CH2S)](CO)6 replaces Fe2(SCH2)2(CO)6, there is almost no catalytic effect.

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047] d) In the method of the present invention, the reducing agent hydrazine hydrate is essential. Under the same other reaction conditions, without adding the reducing agent hydrazine hydrate, there is no product, resulting in the failure of the reaction.

[0048]

[0049]

[0050] e) In the process of implementing the present invention, the inventors experimented on the basis of the dosages of the catalyst hydrogenase mimic Fe2(SCH2)2(CO)6 and the reducing agent hydrazine hydrate required to be protected by the present application. When reducing the dosages, the reaction yields all decreased to varying degrees.

[0051]

[0052] f) In one embodiment of the method of the present invention, although the organic solvent ethanol used is one of the common organic solvents, in the process of implementing the present invention, the inventors verified through experiments that when using ethanol as the organic solvent, the chemical reaction effect is significantly better than other common organic solvents such as acetonitrile, dichloromethane, ethanol, isopropanol, and DMF.

[0053]

[0054] g) In the process of implementing the present invention, the inventors compared different reaction temperatures through experiments, especially in the range of 70 - 90 °C​​​​​​​​​​

[0055] A detailed comparison was carried out within the range, and it was found that the yield was the best when the reaction temperature was 80 °C.

[0056] h) In the process of implementing the present invention, the inventors found that not all aromatic nitro compounds can be used as the substrates for preparing aromatic amine compounds by the method of the present invention. The aromatic nitro compounds described in the method of the present invention do not include 3,4-dichloronitrobenzene, and there should be no group on the benzene ring of the aromatic nitro compound that is more oxidizing than the nitro group.

[0057] For the method of the present invention for preparing aromatic amine compounds, the aromatic nitro compound, excluding 3,4-dichloronitrobenzene, should not have a group on its benzene ring with an oxidation ability stronger than that of the nitro group. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 1H NMR spectrum of the product in Example 1.

[0059] Figure 2 13C NMR spectrum of the product in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0060] The following is described in conjunction with specific embodiments.

[0061] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention.

[0062] The method for preparing aromatic amine compounds described in this embodiment uses aromatic nitro compounds as substrates, ethanol as an organic solvent, hydrazine hydrate as a reducing agent, and a hydrogenase mimetic Fe2(SCH2)2(CO)6 as a catalyst to prepare aromatic amine compounds through a catalytic reduction reaction. Among them, the molar amount of Fe2(SCH2)2(CO)6 is 5-10% of the molar amount of the aromatic nitro compound, the concentration of the aromatic nitro compound ethanol solution is 0.08-0.1 mol / L, the molar ratio of the reducing agent to the aromatic nitro compound is 10-11:1, the reaction temperature is 75-85 °C, and the reaction time is 24-48 h. After the reaction is completed, the aromatic amine compounds can be separated by conventional column chromatography or thin layer chromatography analysis. The organic solvent used for separation is a mixed solvent of petroleum ether and ethyl acetate.

[0063] Tests have proved that the reaction system of the present invention is stable, the operation is simple, the catalyst has good effects, the yield is high, and the product is easy to separate and purify.

[0064] Example 1

[0065] This example is an actual case of preparing p - methoxyaniline.

[0066] The chemical preparation process of p - methoxyaniline is as follows:

[0067]

[0068] The specific preparation steps are as follows:

[0069] p - Nitroanisole (15.3 mg, 0.1 mmol, 1.0 equiv), Fe2(SCH2)2(CO)6 (3.7 mg, 0.01 mmol, 10% mmol), N2H4·H2O (48.8 μL, 1.0 mmol, 10 equiv) and ethanol (1.0 mL) were stirred and mixed evenly, and then reacted under sealing at 80 °C for 24 h. After the reaction was completed, it was purified by column chromatography using petroleum / ethyl acetate to obtain off - white solid p - methoxyaniline (alias p - aminophenol methyl ether, 11.4 mg), with a yield of 93%.

[0070] Structure characterization data of the product: 1 1H NMR (600 MHz, CDCl3, TMS) δ 6.74 (d, J = 8.8 Hz, 2H), 6.64 (d, J = 8.8 Hz, 2H), 3.73 (s, 3H), 3.35 (s, 2H) ppm, and the 1H nuclear magnetic resonance spectrum is as Figure 1 shown; 13 13C NMR (150 MHz, CDCl3, TMS) δ 152.86, 139.90, 116.41, 114.84, 55.73 ppm, and the 13C nuclear magnetic resonance spectrum is as Figure 2 shown.

[0071] Example 2

[0072] This example is an actual case of preparing p - bromoaniline.

[0073] The chemical preparation process of p - bromoaniline is as follows:

[0074]

[0075] The specific preparation steps are as follows:

[0076] 4-Nitrobromobenzene (20.2 mg, 0.1 mmol, 1.0 equiv), Fe2(SCH2)2(CO)6 (3.7 mg, 0.01 mmol, 10% mmol), N2H4·H2O (48.8 μL, 1.0 mmol, 10 equiv) and ethanol (1.0 mL) were stirred and mixed evenly, and then reacted sealed at 80 °C for 24 h. After the reaction was completed, it was purified by column chromatography using petroleum / ethyl acetate to obtain 12.6 mg of yellow solid p-bromoaniline with a yield of 73%.

[0077] Structure characterization data of the product: 1 1H NMR (600 MHz, CDCl3, TMS) δ 7.16 (d, J = 8.7 Hz, 2H), 6.49 (d, J = 8.7 Hz, 2H); 13 13C NMR (150 MHz, CDCl3, TMS) δ 145.38, 131.99, 116.68, 110.20.

[0078] Example 3

[0079] This example is an actual case of preparing p-iodoaniline.

[0080] Its chemical preparation process is as follows:

[0081]

[0082] The specific preparation steps are as follows:

[0083] 4-Nitroiodobenzene (24.9 mg, 0.1 mmol, 1.0 equiv), Fe2(SCH2)2(CO)6 (3.7 mg, 0.01 mmol, 10% mmol), N2H4·H2O (48.8 μL, 1.0 mmol, 10 equiv) and ethanol (1.0 mL) were stirred and mixed evenly, and then reacted sealed at 80 °C for 24 h. After the reaction was completed, it was purified by column chromatography using petroleum / ethyl acetate to obtain 21.7 mg of off-white solid p-iodoaniline with a yield of 99%.

[0084] Structure characterization data of the product: 1 1H NMR (600 MHz, CDCl3, TMS) δ 7.40 (d, J = 8.1 Hz, 2H), 6.47 (d, J = 8.1 Hz, 2H), 3.25 (s, 2H); 13 13C NMR (150 MHz, CDCl3, TMS) δ 145.99, 137.89, 117.29.

[0085] Example 4

[0086] This example is a practical case of preparing o-phenylenediamine.

[0087] The chemical preparation process of o-phenylenediamine is as follows:

[0088]

[0089] The specific preparation steps are as follows:

[0090] Stir and mix 2-nitroaniline (13.8 mg, 0.1 mmol, 1.0 equiv), Fe2(SCH2)2(CO)6 (3.7 mg, 0.01 mmol, 10% mmol), N2H4·H2O (48.8 μL, 1.0 mmol, 10 equiv) and ethanol (1.0 mL) evenly, then seal and react at 80 °C for 24 h. After the reaction is completed, purify by column chromatography using petroleum / ethyl acetate to obtain 10.7 mg of white solid o-phenylenediamine, with a yield of 99%.

[0091] Structure characterization data of the product: 1 H NMR (600 MHz, CDCl3, TMS) δ 6.74–6.67 (m, 4H), 3.37 (s, 4H); 13 C NMR (150 MHz, CDCl3, TMS) δ 134.71, 120.26, 116.74.

[0092] Example 5

[0093] This example is a practical case of preparing m-phenylenediamine.

[0094] The chemical preparation process of m-phenylenediamine is as follows:

[0095]

[0096] The specific preparation steps are as follows:

[0097] Stir and mix 3-nitroaniline (13.8 mg, 0.1 mmol, 1.0 equiv), Fe2(SCH2)2(CO)6 (3.7 mg, 0.01 mmol, 10% mmol), N2H4·H2O (48.8 μL, 1.0 mmol, 10 equiv) and ethanol (1.0 mL) evenly, then seal and react at 80 °C for 24 h. After the reaction is completed, purify by column chromatography using petroleum / ethyl acetate to obtain 9.9 mg of white solid m-phenylenediamine, with a yield of 92%.

[0098] Structure characterization data of the product: 11H NMR (600 MHz, CDCl3, TMS) δ 6.93 (t, J = 7.9 Hz, 1H), 6.11 (d, J = 7.4 Hz, 2H), 6.02 (s, 1H), 3.55 (s, 4H); 13 13C NMR (150 MHz, CDCl3, TMS) δ 147.49, 130.17, 105.97, 101.91.

[0099] Example 6

[0100] This example is an actual case of preparing o-aminophenol.

[0101] The chemical preparation process of o-aminophenol is as follows:

[0102]

[0103] The specific preparation steps are as follows:

[0104] 2-Nitrophenol (13.9 mg, 0.1 mmol, 1.0 equiv), Fe2(SCH2)2(CO)6 (3.7 mg, 0.01 mmol, 10% mmol), N2H4·H2O (48.8 μL, 1.0 mmol, 10 equiv) and ethanol (1.0 mL) were stirred and mixed evenly, and then reacted sealed at 80 °C for 24 h. After the reaction was completed, it was purified by column chromatography using petroleum / ethyl acetate to obtain 10.5 mg of black solid o-aminophenol, with a yield of 96%.

[0105] Structure characterization data of the product: 1 1H NMR (600 MHz, DMSO-d6, TMS) δ 8.93 (s, 1H), 6.63 (dd, J = 7.7, 1.4 Hz, 1H), 6.58 (dd, J = 7.7, 1.7 Hz, 1H), 6.53 (td, J = 7.5, 1.4 Hz, 1H), 6.39 (td, J = 7.5, 1.7 Hz, 1H), 4.47 (s, 2H); 13 13C NMR (150 MHz, DMSO-d6, TMS) δ 144.41, 136.93, 119.93, 116.88, 114.89, 114.81.

[0106] Example 7

[0107] This example is an actual case of preparing 3-aminobenzyl alcohol.

[0108] The chemical preparation process of 3-aminobenzyl alcohol is as follows:

[0109]

[0110] The specific preparation steps are as follows:

[0111] 3-Nitrobenzyl alcohol (15.3 mg, 0.1 mmol, 1.0 equiv), Fe2(SCH2)2(CO)6 (3.7 mg, 0.01 mmol, 10% mmol), N2H4·H2O (48.8 μL, 1.0 mmol, 10 equiv) and ethanol (1.0 mL) were stirred and mixed evenly, and then reacted under sealing at 80 °C for 24 h. After the reaction was completed, it was purified by column chromatography using petroleum / ethyl acetate to obtain 12.2 mg of yellow solid 3-aminobenzyl alcohol, with a yield of 99%.

[0112] Structural characterization data of the product: 1 H NMR (600 MHz, DMSO-d6, TMS) δ 6.90 (t, J = 7.7 Hz, 1H), 6.50 (s, 1H), 6.39 (dd, J = 17.0, 8.1 Hz, 2H), 4.95 (d, J = 13.1 Hz, 3H), 4.30 (d, J = 5.8 Hz, 2H); 13 C NMR (150 MHz, DMSO-d6, TMS) δ 148.84, 143.54, 128.88, 114.47, 112.77, 112.55, 63.66.

[0113] Comparative Example 1

[0114] This comparative example is one of the valuable experiences obtained by the inventor during the process of completing the present invention. An attempt was made to prepare p-methoxyaniline using the hydrogenase mimic [Fe2(SCH2CH2CH2S)](CO)6 as a catalyst, and its chemical preparation process is as follows:

[0115]

[0116] The specific preparation steps are as follows:

[0117] p-Nitroanisole (15.3 mg, 0.1 mmol, 1.0 equiv), Fe2(SCH2CH2CH2S)(CO)6 (3.8 mg, 0.01 mmol, 10% mmol), N2H4·H2O (48.8 μL, 1.0 mmol, 10 equiv) and ethanol (1.0 mL) were stirred and mixed evenly, and then reacted under sealing at 80 °C for 24 h. The expected product was not obtained as a result of the reaction.

[0118] Comparative Example 2

[0119] This comparative example is one of the valuable experiences obtained by the inventor during the process of completing the present invention. An attempt was made to prepare 3,4-dichloroaniline,

[0120] The chemical preparation process is as follows:

[0121]

[0122] The specific preparation steps are as follows:

[0123] 3,4-Dichloronitrobenzene (19.2 mg, 0.1 mmol, 1.0 equiv), Fe2(SCH2)2(CO)6 (3.7 mg, 0.01 mmol, 10% mmol), N2H4·H2O (48.8 μL, 1.0 mmol, 10 equiv) and ethanol (1.0 mL) were stirred and mixed evenly, and then reacted sealed at 80 °C for 24 h. As a result, the expected product 3,4-dichloroaniline was not obtained.

[0124] Other valuable experiences:

[0125] The inventor also tried not to add the catalyst hydrogenase mimic Fe2(SCH2)2(CO)6, and reacted p-nitroanisole (15.3 mg, 0.1 mmol, 1.0 equiv) and N2H4·H2O (48.8 μL, 1.0 mmol, 10 equiv) in an ethanol solvent, and hardly any product was obtained.

[0126] The inventor also tried to add the reducing agent hydrazine hydrate, and reacted p-nitroanisole (15.3 mg, 0.1 mmol, 1.0 equiv), added the catalyst hydrogenase mimic Fe2(SCH2)2(CO)6 (3.7 mg, 0.01 mmol, 10% mmol) and the solvent ethanol (1.0 mL) together, but no product was obtained and the reaction failed.

[0127] The inventor also tried to react p-nitroanisole (15.3 mg, 0.1 mmol, 1.0 equiv), Fe2(SCH2)2(CO)6 (3.7 mg, 0.01 mmol, 10% mmol), N2H4·H2O (48.8 μL, 1.0 mmol, 10 equiv) in different common solvents such as acetonitrile, dichloromethane, ethanol, isopropanol, DMF, etc., and found that the reaction was optimal when ethanol was used as the solvent.

[0128] The above are only the preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as a limitation to the present invention. The protection scope of the present invention should be subject to the scope defined by the claims. For those of ordinary skill in the art, without departing from the spirit and scope of the present invention, several improvements and retouches can still be made, and these improvements and retouches should also be regarded as within the protection scope of the present invention.

Claims

1. A method for preparing aromatic amine compounds, which comprises dissolving an aromatic nitro compound in an organic solvent and obtaining the corresponding aromatic amine compound through a catalytic reduction reaction, wherein the reducing agent is hydrazine hydrate, and is characterized in that, The catalyst used is a hydrogenase mimic; the reaction is sealed, with the temperature being 75 - 85 °C and the time being 24 - 48 h; The structural formula of the aromatic nitro compound is as shown in Formula I: In Formula I, the R1 group is a group with weaker oxidizing property than nitro or nitro; The aromatic amine compound is as shown in Formula II: In Formula II, the R2 group is a group with weaker oxidizing property than nitro or amino; The hydrogenase mimic is Fe2(SCH2)2(CO)6, and the molar amount of the catalyst is 5 - 10% of the molar amount of the aromatic nitro compound.

2. The method for preparing aromatic amine compounds according to claim 1, wherein The organic solvent is ethanol, and the concentration of the aromatic nitro compound ethanol solution is 0.08 - 0.1 mol / L.

3. The method for preparing aromatic amine compounds according to claim 1, wherein The molar ratio of the reducing agent to the aromatic nitro compound is 10 - 11:

1.

4. The method for preparing aromatic amine compounds according to claim 1, characterized in that, The R1 group is any one of alkyl, alkenyl, halogenated group, nitro, amino, hydroxyl, carboxyl.

5. The method for preparing aromatic amine compounds according to claim 4, wherein, The alkyl is methyl.

6. The method for preparing aromatic amine compounds according to claim 4, wherein The R1 group is located at one or more of the ortho - position, meta - position, para - position of the nitro group on the benzene ring.

7. The method for preparing an aromatic amine compound according to claim 4, wherein The aromatic nitro compound is: A. p - nitroanisole, used for preparing methoxyaniline; B. 4 - nitro - bromobenzene, used for preparing p - bromoaniline; C. 4 - nitro - iodobenzene, used for preparing p - iodoaniline; D. 2 - nitroaniline, used for preparing o - phenylenediamine; E. 3 - nitroaniline, used for preparing m - phenylenediamine; F. 2 - nitrophenol, used for preparing o - aminophenol; G. 3 - nitrobenzyl alcohol, used for preparing 3 - aminobenzyl alcohol.

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