How to Distinguish Vinyl Chloropropene Chloroprene

In the chemical industry, vinyl chloride, allyl chloride and chloroprene are three common chlorinated olefins, which are significantly different in chemical properties, molecular structures and practical applications. Distinguishing these three substances is essential for chemical production, quality control, and safe operation. This article will analyze in detail how to distinguish vinyl chloride, chloroprene, and chloroprene from the aspects of molecular structure, physical properties, chemical properties, and storage conditions.

1. Molecular Structure Differences

1. Vinyl chloride (Ethylene Chloride) The molecular structure of vinyl chloride is CH₂ = CHCl, and there are two carbon atoms and one chlorine atom in the molecule. The chlorine atom is bonded to a carbon atom through a covalent bond, and the whole molecule is in a planar structure. Vinyl chloride is a colorless liquid with a pungent odor.

2. Allyl chloride (Propylene Chloride) The molecular structure of chloropropene is CH₂ = CHCH₂ Cl, and there are three carbon atoms and one chlorine atom in the molecule. The chlorine atom is connected to the middle carbon atom, and the structure is slightly complicated. Allyl chloride is also a colorless liquid, but its odor is different from vinyl chloride.

3. Chloroprene (Tetrachloroethane) The molecular structure of chloroprene is C₂ H4Cl4, with two carbon atoms and four chlorine atoms in the molecule. The structure is symmetrical, with a rhombohedral crystal. Chloroprene is a colorless liquid commonly used in fire fighting and cleaning.

2. physical property differences

1. melting point and boiling point

• Vinyl chloride has a melting point of -95.5°C and a boiling point of 135.9°C.
• Chloropropene has a melting point of -96.2°C and a boiling point of 141.3°C.
• chloroprene has a melting point of -94.5°C and a boiling point of 140.7°C.
  It can be seen from the above data that the melting points and boiling points of the three are relatively close, but vinyl chloride is slightly lower, while chloropropene and chloroprene have similar boiling points.

1. Density

• Vinyl chloride has a density of 1.45g/cm³.
• Tritiated propylene has a density of 1.50g/cm³.
The density of
• chloroprene is 1.27g/cm³.
  The density of the three is different, which can be distinguished by density test.

1. smell
   Vinyl chloride has a pungent odor similar to that of chlorinated water; allyl chloride has an odor similar to that of ethylene; chloroprene has no distinct odor.

3. chemical differences

1. Stability Vinyl chloride is easy to decompose at high temperature, and the decomposition products are ethylene and hydrogen chloride; allyl chloride is also decomposed at high temperature, but the decomposition products are different; chloroprene is relatively stable at room temperature, but decomposition reaction may occur at high temperature.

2. Reactivity

• Vinyl chloride in the light easily with oxygen reaction, the generation of chlorinated carbonyl and carbon dioxide;
• Chloropropene in the light also with oxygen reaction, generating acrolein and carbon dioxide;
• Chloroprene in the light is more stable, not easy to decomposition reaction.

1. 
   of chemical reaction test These three substances can be distinguished by specific chemical reactions. For example, adding nitrobenzene to the three liquids, shaking and standing, vinyl chloride will be miscible with nitrobenzene, while chloropropene and chloroprene will stratify. Further tests can be identified by their different reaction characteristics.

4. storage conditions

1. vinyl chloride Vinyl chloride should be stored in a well-ventilated and cool place, away from direct sunlight and high temperature. When storing, use moisture-proof, dust-proof containers, and keep away from fire and oxidizing agents.

2. allyl chloride The storage conditions of chloropropene are similar to those of vinyl chloride, but special attention needs to be paid to its flammable characteristics. Flame-proof and explosion-proof containers shall be used for storage, and contact with fire sources shall be avoided.

3. chloroprene Chloroprene storage conditions are relatively loose, but should be stored in a cool, well-ventilated place, away from direct sunlight. Chloroprene needs to be stored to prevent contamination, especially to avoid contact with water vapor.

5. Practical Application of Distinction

In practice, these three substances can be distinguished by the following methods:

1. molecular structure analysis The molecular structure is tested by light or chemical reaction to determine the type of substance.

2. Physical Property Test By measuring the melting point, boiling point, density and other physical properties, combined with odor to determine the type of substance.

3. Chemical Reaction Testing Through specific chemical reactions, the reaction characteristics of substances are observed to achieve differentiation.

6. conclusion

Vinyl chloride, allyl chloride and chloroprene, as chlorinated olefins, have different molecular structures, physical properties and chemical properties. Through molecular structure analysis, physical property test and chemical reaction test, these three substances can be effectively separated. In chemical production, accurately distinguishing these three substances is essential to ensure production safety and product quality.