Manufacturing method of p-nitroaniline
I. Introduction
P-nitroaniline is an important organic chemical raw material, which is widely used in the fields of dyestuffs, pharmaceuticals and pesticides. Therefore, it is of great practical significance to study the manufacturing method of p-nitroaniline. In this paper, we will introduce the method of preparing p-nitroaniline by reduction reaction using p-nitrochlorobenzene as raw material.
II.Experimental principle
The preparation of p-nitroaniline is the process of converting p-nitrochlorobenzene to amino group by reducing the chlorine atom in it. The reducing agent can be chosen from hydrogen gas, zinc powder, iron powder and so on. In this experiment, hydrogen is used as the reducing agent to realize the reduction of p-nitrochlorobenzene by catalytic hydrogenation reaction.
III. Experimental steps
1. Pretreatment of p-nitrochlorobenzene
A certain amount of p-nitrochlorobenzene was added into a three-necked flask, a small amount of zinc powder was added as a catalyst, and it was heated and stirred until the zinc powder was completely dissolved. Then cooled to room temperature with an ice water bath, filtered to remove insoluble matter to obtain the pretreated p-nitrochlorobenzene solution. Reduction reaction
2. Reduction reaction
Add the pretreated p-nitrochlorobenzene solution to the autoclave, pass hydrogen, pressurize to a certain pressure, heat to a certain temperature, and start the reduction reaction. During the reaction process, the temperature and pressure of the reaction solution should be constantly monitored to maintain constant temperature and pressure.
3. Post-treatment
After the reaction is finished, cool to room temperature, pour the reaction solution into a dispensing funnel and wash it with water several times to remove acidic impurities. Then adjust the pH to neutral with alkaline solution and wash with water again several times to obtain the crude product of p-nitroaniline.
4. Purification
The crude product was recrystallized with ethanol to obtain purified p-nitroaniline.
4. Experimental Results and Discussion
1. Experimental Results
By organizing and analyzing the experimental data, we obtained the yield and purity data of p-nitroaniline.
2. Discussion of results
The temperature and pressure of the reduction reaction are the key factors affecting the yield and purity of p-nitroaniline. Too high temperature and pressure may lead to the occurrence of side reactions and reduce the purity of the product; too low temperature and pressure may lead to incomplete reaction and reduce the yield of the product. Therefore, the reaction conditions need to be continuously optimized in the experiments to obtain the best reaction results. In addition, the amount of zinc powder as a catalyst needs to be controlled appropriately, and too much zinc powder may lead to too high a content of metal impurities in the product.
V. Conclusion
Through the analysis and discussion of the experimental data, we came to the following conclusion: p-nitroaniline can be successfully prepared by catalytic hydrogenation reaction using p-nitrochlorobenzene as raw material. In the experimental process, the temperature and pressure of the reduction reaction, as well as the amount of catalyst, need to be controlled in order to obtain p-nitroaniline products with high purity and high yield. The preparation method has the advantages of easy operation, easy availability of raw materials, high purity of product, and has certain industrial application value.
