[Chemical Knowledge]：The nature, use, upstream and downstream raw materials, storage methods of nitrobenzene, what are the properties of nitrobenzene

Properties of nitrobenzene

nitrobenzene (C6H5NO2) is a pale yellow oily liquid with a significant bitter almond odor. It has a density of about 1.20g/cm³, a melting point of 5.7°C and a boiling point of 210.9°C. Nitrobenzene is insoluble in water, but it is miscible with organic solvents such as ethanol and ether. The chemical properties of nitrobenzene are relatively stable, but it is easy to produce aniline in the presence of high temperature or strong reducing agent. As an important organic intermediate, nitrobenzene exhibits unique reactivity in a variety of chemical reactions.

Use of nitrobenzene

nitrobenzene is widely used in many chemical industries. Its main uses include:

1. aniline production: The most important use of nitrobenzene is to be used as a precursor of aniline. Nitrobenzene can be efficiently converted into aniline through hydrogenation reduction or iron powder acid reduction.
2. Dyes and Pigments: Nitrobenzene and its derivatives are key intermediates in the production of many dyes and pigments. For example, nitrobenzene is often used in the synthesis of azo dyes.
3. Pesticides and pharmaceutical intermediates nitrobenzene also plays an important role in the synthesis of pesticides such as herbicides and insecticides. In addition, the synthesis of certain pharmaceutical products also relies on nitrobenzene and its derivatives.
4. Rubber Chemicals nitrobenzene is also used in the production of rubber accelerators and antioxidants to improve the performance and life of rubber products.

Upstream feedstock of nitrobenzene

the production of nitrobenzene mainly uses benzene and concentrated nitric acid as raw materials. In the production process, nitrobenzene is generated by nitrating benzene with mixed acid (mixture of sulfuric acid and nitric acid). The specific reaction is as follows: [C6H6 HNO3 \rightarrow C6H5NO2 H2O]

1. benzene benzene is one of the basic raw materials of petrochemical industry, which is separated from petroleum fractions by catalytic reforming, hydrocracking and other methods.
2. Nitric acid industrial nitric acid is mainly prepared by ammonia oxidation method, that is, nitric oxide is generated by the reaction of ammonia and air at high temperature, and then concentrated nitric acid is generated by a series of oxidation and absorption reactions.
3. sulfuric acid sulfuric acid is an auxiliary reagent in the nitration reaction, which is used to absorb the water generated in the reaction and increase the effective concentration of nitric acid.

Downstream products of nitrobenzene

the main downstream products of nitrobenzene include aniline and its derivatives, dyes, pesticides, rubber chemicals, etc:

1. aniline and its derivatives: Aniline is an important chemical intermediate used in the production of a variety of dyes, pesticides, pharmaceuticals and polyurethane materials.
2. Dyes these include azo dyes, nitro dyes, etc., which are widely used in the textile, leather and plastics industries.
3. Pesticides such as herbicides, pesticides, nitrobenzene derivatives in these products play an important role.
4. Rubber Chemicals: Including accelerators, antioxidants, etc., to improve the performance and service life of rubber.

Production process of nitrobenzene

the production process of nitrobenzene mainly includes the following steps:

1. mixed acid preparation sulfuric acid and nitric acid are mixed in a certain proportion to prepare a mixed acid.
2. nitration reaction nitration reaction of benzene and mixed acid in the reactor to produce nitrobenzene. The reaction temperature should be strictly controlled at 60-70 ℃ to ensure the smooth progress of the reaction and the high purity of the product.
3. separation and washing the nitrobenzene produced by the reaction is separated and washed with water several times to remove residual acid and impurities.
4. Drying and refining the washed nitrobenzene is dried to remove water and obtain pure nitrobenzene.

Storage Methods of Nitrobenzene

the storage of nitrobenzene requires special attention to safety and environmental protection issues:

1. storage Environment: Nitrobenzene should be stored in a cool, well-ventilated special warehouse to avoid direct sunlight and high temperature environment to prevent decomposition and explosion risks.
2. Container Requirements: Use a corrosion-resistant airtight container to store nitrobenzene to avoid container leakage and air contact, and prevent oxidation and pollution.
3. Fire Prevention Measures: The warehouse shall be equipped with sufficient fire-fighting equipment to prevent explosion hazards caused by fire. At the same time, the warehouse should be kept away from fire and heat sources and maintain a low temperature environment.
4. Leakage treatment in case of leakage, it is necessary to cover and clean the leakage with sand immediately to prevent it from entering the sewer or polluting the water source. At the same time, the operator should wear protective equipment to avoid direct contact with nitrobenzene.

Safety and Environmental Protection of Nitrobenzene

nitrobenzene has certain toxicity and environmental hazards:

1. health Hazards nitrobenzene is toxic to the human body, and long-term exposure can lead to blood system diseases, such as hemolytic anemia and liver damage. Inhalation of high concentrations of nitrobenzene vapor can cause headaches, nausea and difficulty breathing, and can be fatal in severe cases.
2. Environmental impact nitrobenzene has a certain persistence in the environment and is toxic to aquatic organisms, which may lead to water pollution and ecosystem destruction. Therefore, in the process of production and use, it is necessary to strictly control emissions to avoid environmental pollution.

Conclusion

as an important chemical intermediate, nitrobenzene is widely used in industrial production. Its toxicity and environmental hazards cannot be ignored. Therefore, it is necessary to strictly abide by safety and environmental protection regulations during production, storage and use to ensure production safety and environmental protection. By improving the production process and using substitutes, the environmental risk of nitrobenzene can be further reduced and the sustainable development of the chemical industry can be promoted.