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Synthesis method of p-phenylenediamine

A technology of p-phenylenediamine and synthesis method, applied in the direction of preparation through nitrogen-oxygen/nitrogen-nitrogen bonds, organic chemistry, etc., can solve the problems of cumbersome routes and pollution of p-phenylenediamine, and achieve good industrial implementation prospects, reaction Simple steps and high product purity

Active Publication Date: 2020-02-21
TSINGHUA UNIV
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Problems solved by technology

[0005] The purpose of this invention is to provide a kind of synthetic method of p-phenylenediamine, solve the problem that the route of synthetic p-phenylenediamine by p-nitroaniline reduction method in the prior art is loaded down with trivial details and pollution is serious in the nitration process, to existing p-phenylenediamine The synthesis method of diamine is improved, using aniline as raw material, the product of p-phenylenediamine is obtained through diazotization reaction, heating rearrangement, and hydrogenation reduction reaction, and the preparation process is safe and environmentally friendly, and the discharge of three wastes is less

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  • Synthesis method of p-phenylenediamine

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[0019] The synthetic method of p-phenylenediamine that the present invention proposes, its synthetic route is as figure 1 shown, including the following steps:

[0020] (1) Synthesis of 1,3-diphenyltriazene:

[0021] Add aniline, molar concentration in water and be the concentrated hydrochloric acid of 12mol / L, the volume ratio of aniline, concentrated hydrochloric acid and water is: aniline: concentrated hydrochloric acid: water=1:(1~2):(5~10), obtain the first solution; under ice-bath conditions, sodium nitrite solution is added dropwise to the first solution, so that the mol ratio of aniline and sodium nitrite is (1.5~2): 1, an alkaline solution is added in the reactant, and the pH value is adjusted to 4~6, react for 0.5~2 hours, get 1,3-diphenyltriazene precipitate, filter to get 1,3-diphenyltriazene;

[0022] (2) Synthesis of 4-aminoazobenzene:

[0023] Add the 1,3-diphenyltriazene and the concentrated acid of step (1) to the solvent, and the addition ratio is: 1,3-dip...

Embodiment 1

[0033] (1) Synthesis of 1,3-diphenyltriazene: Add aniline (6.5 mL), 12 mol / L concentrated hydrochloric acid (6.5 mL) and water (32.5 mL) into a flask. Stir for a period of time to fully dissolve the aniline in the system, then place the reaction bottle in an ice bath, and add aqueous sodium nitrite solution (molar ratio of sodium nitrite to aniline = 1:1.5) dropwise to the above system. After that, sodium carbonate solution (molar concentration 1mol / L) was added dropwise to adjust the pH to 4, a large amount of light yellow precipitates could be observed, and the reaction was stirred for 0.5 hours. Filtrate with suction and wash several times with ultrapure water to obtain 1,3-diphenyltriazene. figure 2 For the 1,3-diphenyltriazene prepared in embodiment 1 1 HNMR spectrum.

[0034] (2) Synthesis of 4-aminoazobenzene: Methanol (2 mL) and 1,3-diphenyltriazene (1 g) were added to a flask. Then add 12mol / L concentrated hydrochloric acid (0.5mL) to the system under stirring con...

Embodiment 2

[0037](1) Synthesis of 1,3-diphenyltriazene: Add aniline (6.5 mL), 12 mol / L concentrated hydrochloric acid (7.8 mL) and water (39 mL) into a flask. Stir for a period of time to fully dissolve the aniline in the system, then place the reaction bottle in an ice bath, and add aqueous sodium nitrite solution (molar ratio of sodium nitrite to aniline = 1:1.6) dropwise to the above system. Afterwards, sodium acetate solution (molar concentration: 1.2 mol / L) was added dropwise to adjust the pH to 4.4, a large amount of light yellow precipitates could be observed, and the reaction was stirred for 0.8 hours. Filtrate with suction and wash several times with ultrapure water to obtain 1,3-diphenyltriazene.

[0038] (2) Synthesis of 4-aminoazobenzene: Add ethanol (2.6 mL) and 1,3-diphenyltriazene (1 g) into a flask. Then add concentrated nitric acid (0.8mL) to the system under stirring condition, stir well to dissolve the solid, raise the temperature to 48°C, and react for 1.7 hours to o...

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Abstract

The invention relates to a synthesis method of p-phenylenediamine, and belongs to the technical field of organic material preparation. Aniline adopted as a raw material undergoes a diazotization reaction and a heating rearrangement reaction to generate 4-aminoazobenzene, a proper amount of an acid is added, and the 4-aminoazobenzene is separated out; the 4-aminoazobenzene is dissolved in a propersolvent, a catalyst is added, the p-phenylenediamine product is obtained through a hydrogenation reduction reaction, filtration and reduced pressure distillation, and aniline is recovered as a byproduct and can be recycled as the raw material. Compared with an existing p-phenylenediamine production method, the method of the invention has the advantages of safe and environmentally-friendly preparation process, little emission of three wastes, easily available reaction raw materials, simple reaction steps, and high purity of the finally prepared product, so the method has good industrial implementation prospects.

Description

technical field [0001] The invention relates to a synthesis method of p-phenylenediamine, which belongs to the technical field of organic material preparation. Background technique [0002] p-Phenylenediamine is an important organic intermediate. Its uses include the preparation of polyimide, para-aramid fiber, dye, rubber anti-aging agent, photo developer, petroleum product additive, flame retardant, etc., and is widely used in Dye, washing chemical, rubber, national defense and other industries. [0003] At present, the main production process of p-phenylenediamine is the reduction process of p-nitroaniline. In the traditional p-nitroaniline reduction method, the raw material p-nitroaniline needs to be obtained from chlorobenzene through nitration and ammonolysis, the synthesis route is cumbersome and the pollution is serious during the nitration process. The reduction process can use iron powder reduction, alkali sulfide reduction, hydrogenation reduction, etc. Alkali ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C209/42C07C211/55
CPCC07C209/42C07C245/08C07C245/24C07C211/55
Inventor 和亚宁庹新林
Owner TSINGHUA UNIV
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