vinyl chloride

vinyl chloride, a colourless, flammable, toxic gas belonging to the family of organohalogen compounds and used principally in making polyvinyl chloride, or PVC, a widely used plastic with numerous applications.

The major industrial preparation of vinyl chloride begins with ethylene and has two variants. In one, ethylene is converted to 1,2-dichloroethane (ethylene chloride) by reaction with chlorine. Heating 1,2-dichloroethane in the presence of a charcoal catalyst gives vinyl chloride.

In the other process (called oxychlorination), ethylene, hydrogen chloride, and oxygen (or air) are heated in the presence of a copper catalyst to give vinyl chloride and water.

Typically, a vinyl chloride plant is designed to integrate the two processes so that the hydrogen chloride produced by heating 1,2-dichloroethane is used as a reactant in the oxychlorination method.

Processes based on acetylene were developed in the 1930s and are more direct, but because acetylene is much more expensive than ethylene, these processes are used far less than ethylene-based ones.

Vinyl chloride can cause liver damage, and it is classified as a known human carcinogen.