How to distinguish between olefins and benzene

Olefins and benzene are two very important basic substances in the chemical industry, and they are significantly different in structure, properties and applications. This article will analyze in detail how to distinguish between olefins and benzene from multiple perspectives to help readers better understand their differences.

Molecular Structure and Basic Composition of 1.

1. Structural features The olefin molecule contains a carbon-carbon double bond and has unsaturation. The benzene molecule is composed of three carbon rings connected by double bonds, and the structure is very stable. The molecular formula of the olefin is usually CnH2n, while the molecular formula of benzene is C6H6.

2. chemical composition Olefins are hydrocarbons that contain both carbon and hydrogen. Benzene is also a hydrocarbon, but the carbon atoms in its structure are connected by a ring structure and have unique stability.

Physical and Chemical Properties of 2.

1. Physical Properties (1) Density: The density of benzene is about 0.8765g/cm³, which is smaller than water; the density of olefins depends on the specific type, and the density of most olefins is less than water. (2) Solubility: Benzene is slightly soluble in water and completely dissolved in organic solvents; olefins are partially soluble or slightly soluble in water according to different molecular structures.

2. Chemical properties (1) Reactivity: Benzene does not react with strong oxidants, but can undergo addition, substitution and other reactions under specific conditions; olefins contain double bonds and are prone to chemical reactions such as addition and polymerization. (2) Stability: Benzene has a high degree of molecular symmetry and stability, while olefins are relatively unstable due to their unsaturated bonds and are prone to polymerization or addition reactions.

3. identification method

1. physical identification (1) Density determination: The density difference between the two is measured experimentally and distinguished by a densitometer. (2) Solubility test: add the two into the same solvent respectively, and observe the dissolution.

2. chemical identification ((1) bromine water fading: bromine water and olefin addition reaction, so that the solution fade; but benzene does not react with bromine water. (2) Acid potassium permanganate solution reaction: Bromine water fading is an important method to distinguish olefins.

3. instrumental analysis (1) Infrared spectrum analysis: the molecular structure of olefins and benzene is different, and the infrared spectrum characteristics are different, which can be used as the basis for identification. (2) nuclear magnetic resonance (NMR) analysis: the hydrogen bond environment of the two is different, and the nuclear magnetic resonance spectrum has obvious distinguishing characteristics.

4. the difference in practical application

1. industrial production (1) Olefins: Olefins such as ethylene are commonly used in the production of polyolefins, plastics and other products. (2) Benzene: used in the production of organic compounds such as phenol and phenylethanol.

2. Environmental impact (1) Benzene: It is harmful to human body and environment, but it is toxic to some organisms. (2) Olefins: Some olefins such as propylene can be used for combustible explosive materials, and some are used for industrial purposes such as solvents.

5. Summary

from the above analysis, it can be seen that there are significant differences between olefins and benzene in many aspects. Correctly distinguishing them is not only the basic content of chemistry learning, but also an important basis for avoiding misuse in practical work. Chemical practitioners need to combine molecular structure, physical properties and practical application, comprehensive analysis, accurate identification of the two.