阅读说明：本技术 一种对苯二胺的合成方法 (Synthetic method of p-phenylenediamine ) 是由 和亚宁 庹新林 于 2019-10-30 设计创作，主要内容包括：本发明涉及一种对苯二胺的合成方法,属于有机材料制备技术领域。本发明采用苯胺为原料,经重氮化反应、加热重排反应生成4-氨基偶氮苯,加入适量酸可以分离出产品。将4-氨基偶氮苯溶于适当溶剂中,加入催化剂,通过加氢还原反应,经过滤、减压蒸馏得到对苯二胺产品,同时苯胺作为副产物回收,可以循环作为原料使用。与现有的对苯二胺的生产方法相比,本发明方法的制备过程安全环保、三废排放少,同时反应原料易得、反应步骤简便、最后制备得到的产品纯度高,因此本发明方法具有良好的工业实施前景。(The invention relates to a synthetic method of p-phenylenediamine, belonging to the technical field of organic material preparation. The invention adopts aniline as raw material, and produces 4-amino azobenzene through diazotization reaction and heating rearrangement reaction, and adds right amount of acid to separate out the product. Dissolving 4-aminoazobenzene in a proper solvent, adding a catalyst, performing hydrogenation reduction reaction, filtering, and distilling under reduced pressure to obtain a p-phenylenediamine product, wherein aniline is recovered as a byproduct and can be recycled as a raw material. Compared with the existing production method of p-phenylenediamine, the preparation method of the invention has the advantages of safe and environment-friendly preparation process, less discharge of three wastes, easily obtained reaction raw materials, simple and convenient reaction steps and high purity of the finally prepared product, thus the method has good industrial implementation prospect.)

1. The method for synthesizing p-phenylenediamine is characterized by comprising the following steps:

(1) synthesis of 1, 3-diphenyltriazene:

adding aniline and concentrated hydrochloric acid with the molar concentration of 12mol/L into water, wherein the volume ratio of the aniline to the concentrated hydrochloric acid to the water is as follows: aniline, concentrated hydrochloric acid and water, wherein the ratio of (1) - (2) to (5-10) is 1, so as to obtain a first solution; dropwise adding a sodium nitrite solution into the first solution under an ice bath condition to enable the molar ratio of aniline to sodium nitrite to be (1.5-2): 1, adding an alkaline solution into the reactant, adjusting the pH value to be 4-6, reacting for 0.5-2 hours to obtain 1, 3-diphenyltriazene precipitate, and filtering to obtain 1, 3-diphenyltriazene;

(2) synthesis of 4-aminoazobenzene:

adding the 1, 3-diphenyl triazene and the concentrated acid in the step (1) into a solvent according to the following proportion: 1, 3-diphenyltriazene, 1g of concentrated acid and 1g of solvent, (0.5-2) ml of (2-5) ml of the solution, heating the solution to 40-80 ℃, and reacting the solution for 0.5-2 hours to obtain a 4-aminoazobenzene solution; adding a dilute acid solution into a 4-aminoazobenzene solution at room temperature, wherein the adding molar ratio is as follows: 4-aminoazobenzene, diluted acid 1: (1-5), standing for crystallization, filtering and washing to obtain 4-aminoazobenzene;

(3) hydrogenation reduction of 4-aminoazobenzene to obtain p-phenylenediamine:

adding the 4-aminoazobenzene, the solvent and the catalyst in the step (2) into a reaction kettle according to the following proportion: the catalyst is prepared by introducing nitrogen to replace air in a reaction kettle for multiple times and then introducing hydrogen to replace nitrogen in the reaction kettle for multiple times, introducing hydrogen after replacement is finished, and performing hydrogenation reaction at the reaction temperature of 60-100 ℃ for the following reaction time: and (3) filtering the catalyst after the reaction is finished for 0.5-5 hours, and removing the solvent by reduced pressure distillation to obtain the p-phenylenediamine product.

2. The method for synthesizing p-phenylenediamine according to claim 1, wherein the alkaline solution added in step (1) is a sodium carbonate solution or a sodium acetate solution, and the molar concentration of the alkaline solution is 1-2 mol/L.

3. A process for the synthesis of p-phenylenediamine according to claim 1, wherein the solvent used in steps (2) and (3) is aniline, methanol or ethanol.

4. A process for the synthesis of p-phenylenediamine according to claim 1, wherein said concentrated acid in step (2) is concentrated hydrochloric acid, concentrated nitric acid, concentrated sulfuric acid or glacial acetic acid.

5. A process for the synthesis of p-phenylenediamine according to claim 1, wherein said dilute acid in step (2) is dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid or acetic acid solution.

6. A process for the synthesis of p-phenylenediamine according to claim 1, wherein said catalyst in step (3) is a raney nickel catalyst, a platinum carbon catalyst or a ruthenium carbon catalyst.

Technical Field

The invention relates to a synthetic method of p-phenylenediamine, belonging to the technical field of organic material preparation.

Background

P-phenylenediamine is an important organic intermediate, has the application of preparing polyimide, para-aramid, dye, rubber antioxidant, photo developer, petroleum product additive, flame retardant and the like, and is widely applied to the industries of dye, washing, rubber, national defense and the like.

Currently, the main production process of p-phenylenediamine is the p-nitroaniline reduction process. In the traditional p-nitroaniline reduction method, the raw material p-nitroaniline needs to be obtained by nitration and ammonolysis of chlorobenzene, the synthetic route is complicated, and the pollution is serious in the nitration process. The reduction process can be iron powder reduction, alkali sulfide reduction, hydrogenation reduction and the like. The sodium sulfide reduction method is high in safety and is the mainstream method of the current production, but the discharge of waste water and sludge is more in the production process, and the conversion rate of the raw material p-nitroaniline is lower.

The traditional paranitroaniline reduction method has complicated synthetic route and serious pollution in the nitration process, and other synthetic methods are researched at home and abroad, wherein the method for obtaining the p-phenylenediamine by taking the aniline as the raw material and carrying out diazotization, rearrangement and hydrogenation reduction reactions has the advantages of easily obtained raw materials, safety and environmental protection, and has much attention. However, the existing related researches have the problems of low reaction efficiency, low product purity, more three wastes and the like, and the conditions for industrial amplification are not provided. For example, chinese patent CN1116619 discloses a method for producing p-phenylenediamine by low-pressure catalytic hydrogenation, which comprises using aniline as a starting material, adding hydrochloric acid, sodium nitrite and sodium hydroxide into a reaction kettle, mixing, stirring and separating to obtain p-aminoazobenzene, and carrying out catalytic hydrogenation reduction reaction to obtain the p-phenylenediamine product. However, the method completes the steps of diazo coupling, transposition rearrangement and the like in the same reaction kettle, and the transposition rearrangement has low reaction efficiency in water, so that high-purity 4-aminoazobenzene is difficult to obtain, and the quality of the final p-phenylenediamine product is influenced.

Disclosure of Invention

The invention aims to provide a method for synthesizing p-phenylenediamine, which solves the problems of complicated route for synthesizing the p-phenylenediamine by a p-nitroaniline reduction method and serious pollution in a nitration process in the prior art, improves the prior method for synthesizing the p-phenylenediamine, takes aniline as a raw material, obtains a p-phenylenediamine product through diazotization, heating rearrangement and hydrogenation reduction reaction, and ensures that the preparation process is safe and environment-friendly and the discharge of three wastes is less.

The synthesis method of p-phenylenediamine provided by the invention comprises the following steps:

(1) synthesis of 1, 3-diphenyltriazene:

adding aniline and concentrated hydrochloric acid with the molar concentration of 12mol/L into water, wherein the volume ratio of the aniline to the concentrated hydrochloric acid to the water is as follows: aniline, concentrated hydrochloric acid and water, wherein the ratio of (1) - (2) to (5-10) is 1, so as to obtain a first solution; dropwise adding a sodium nitrite solution into the first solution under an ice bath condition to enable the molar ratio of aniline to sodium nitrite to be (1.5-2): 1, adding an alkaline solution into the reactant, adjusting the pH value to be 4-6, reacting for 0.5-2 hours to obtain 1, 3-diphenyltriazene precipitate, and filtering to obtain 1, 3-diphenyltriazene;

(2) synthesis of 4-aminoazobenzene:

adding the 1, 3-diphenyl triazene and the concentrated acid in the step (1) into a solvent according to the following proportion: 1, 3-diphenyltriazene, 1g of concentrated acid and 1g of solvent, (0.5-2) ml of (2-5) ml of the solution, heating the solution to 40-80 ℃, and reacting the solution for 0.5-2 hours to obtain a 4-aminoazobenzene solution; adding a dilute acid solution into a 4-aminoazobenzene solution at room temperature, wherein the adding molar ratio is as follows: 4-aminoazobenzene, diluted acid 1: (1-5), standing for crystallization, filtering and washing to obtain 4-aminoazobenzene;

(3) hydrogenation reduction of 4-aminoazobenzene to obtain p-phenylenediamine:

adding the 4-aminoazobenzene, the solvent and the catalyst in the step (2) into a reaction kettle according to the following proportion: the catalyst is prepared by introducing nitrogen to replace air in a reaction kettle for multiple times and then introducing hydrogen to replace nitrogen in the reaction kettle for multiple times, introducing hydrogen after replacement is finished, and performing hydrogenation reaction at the reaction temperature of 60-100 ℃ for the following reaction time: and (3) filtering the catalyst after the reaction is finished for 0.5-5 hours, and removing the solvent by reduced pressure distillation to obtain the p-phenylenediamine product.

The synthesis method of p-phenylenediamine provided by the invention has the advantages that:

the synthesis method of p-phenylenediamine of the invention takes aniline as raw material, and can obtain high-purity 4-aminoazobenzene through diazotization reaction and heating rearrangement, and then obtains high-purity p-phenylenediamine product through hydrogenation reduction reaction. The preparation process of the method is safe and environment-friendly, the discharge of three wastes is less, the reaction raw materials are easy to obtain, the reaction steps are simple and convenient, and the purity of the finally prepared product is high, so the method has good industrial implementation prospect.

Drawings

FIG. 1 is a schematic diagram of the synthesis scheme of p-phenylenediamine of the process of the present invention.

FIG. 2 is a diagram showing the preparation of 1, 3-diphenyltriazene according to the present invention in step (1) of example 1¹HNMR atlas.

FIG. 3 is a diagram showing a process for preparing 4-aminoazobenzene in step (2) of example 1 of the present invention¹HNMR atlas.

FIG. 4 is a diagram showing a process for producing p-phenylenediamine in step (3) of example 1 of the present invention¹HNMR atlas.

Detailed Description

The synthetic route of the p-phenylenediamine provided by the invention is shown in figure 1, and the synthetic method comprises the following steps:

(1) synthesis of 1, 3-diphenyltriazene:

adding aniline and concentrated hydrochloric acid with the molar concentration of 12mol/L into water, wherein the volume ratio of the aniline to the concentrated hydrochloric acid to the water is as follows: aniline, concentrated hydrochloric acid and water, wherein the ratio of (1) - (2) to (5-10) is 1, so as to obtain a first solution; dropwise adding a sodium nitrite solution into the first solution under an ice bath condition to enable the molar ratio of aniline to sodium nitrite to be (1.5-2): 1, adding an alkaline solution into the reactant, adjusting the pH value to be 4-6, reacting for 0.5-2 hours to obtain 1, 3-diphenyltriazene precipitate, and filtering to obtain 1, 3-diphenyltriazene;

(2) synthesis of 4-aminoazobenzene:

adding the 1, 3-diphenyl triazene and the concentrated acid in the step (1) into a solvent according to the following proportion: 1, 3-diphenyltriazene, 1g of concentrated acid and 1g of solvent, (0.5-2) ml of (2-5) ml of the solution, heating the solution to 40-80 ℃, and reacting the solution for 0.5-2 hours to obtain a 4-aminoazobenzene solution; adding a dilute acid solution into a 4-aminoazobenzene solution at room temperature, wherein the adding molar ratio is as follows: 4-aminoazobenzene, diluted acid 1: (1-5), standing for crystallization, filtering and washing to obtain 4-aminoazobenzene;

(3) hydrogenation reduction of 4-aminoazobenzene to obtain p-phenylenediamine:

adding the 4-aminoazobenzene, the solvent and the catalyst in the step (2) into a reaction kettle according to the following proportion: the catalyst is prepared by introducing nitrogen to replace air in a reaction kettle for multiple times and then introducing hydrogen to replace nitrogen in the reaction kettle for multiple times, introducing hydrogen after replacement is finished, and performing hydrogenation reaction at the reaction temperature of 60-100 ℃ for the following reaction time: and (3) filtering the catalyst after the reaction is finished for 0.5-5 hours, and removing the solvent by reduced pressure distillation to obtain the p-phenylenediamine product. When the solvent in the step is aniline, the solvent obtained by reduced pressure distillation can be used as a raw material for preparing 1, 3-diphenyltriazene, and can be recycled.

In the step (1) of the synthesis method of p-phenylenediamine, the added alkaline solution is a sodium carbonate solution or a sodium acetate solution, and the molar concentration of the alkaline solution is 1-2 mol/L.

The solvent in the step (2) and the step (3) of the method for synthesizing p-phenylenediamine is aniline, methanol or ethanol.

In the step (2) of the synthesis method of p-phenylenediamine, the concentrated acid is concentrated hydrochloric acid, concentrated nitric acid, concentrated sulfuric acid or glacial acetic acid.

In the step (2) of the method for synthesizing p-phenylenediamine, the dilute acid is dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid or acetic acid solution.

In the step (3) of the method for synthesizing p-phenylenediamine, the catalyst is a raney nickel catalyst, a platinum carbon catalyst or a ruthenium carbon catalyst.

Examples of the method of the present invention are further described below, but the scope of the claimed invention is not limited thereto.