Chloroprene

Overview
Chloroprene is the common name for the organic compound 2-chloro-1,3-butadiene, which has the chemical formula C4H5Cl. The chemical structure is shown at right. It is used as monomer for the production of the polymer polychloroprene, a type of synthetic rubber. Polychloroprene is better known to the public as Neoprene, the trade name DuPont gave it when the company first developed it and currently used by DuPont Dow.

Production of chloroprene
The acetylene process was used to produce chloroprene until the 1960s. In this process, acetylene and hydrogen chloride were used as shown here:



This process had disadvantages in that it was very energy-intensive and had high investment costs.

The modern chloroprene process which is currently used by nearly all makers uses butadiene differently. 1,3-Butadiene undergoes addition of chlorine across one of its double bonds in its molecule to give 3,4-dichloro-1-butene. Then this compound undergoes an elimination of a hydrogen atom in the #3 position and the chlorine atom in the #4 position as HCl forming a double bond between the #3 and #4 carbon atoms in the molecule, yielding chloroprene.