1,1-Dichloroethene

1,1-Dichloroethene, commonly called 1,1-dichloroethylene or 1,1-DCE, is an organochloride with the molecular formula C₂H₂Cl₂. It is a colorless liquid with a sharp odor. Like most chlorocarbons, it is poorly soluble in water, but soluble in organic solvents. 1,1-DCE was the precursor to the original cling-wrap for food, but this application has been phased out.

Production

1,1-DCE is produced by dehydrochlorination of 1,1,2-trichloroethane, a relatively unwanted byproduct in the production of 1,1,1-trichloroethane and 1,2-dichloroethane. The conversion involves a base-catalyzed reaction:

The gas phase reaction, without the base, would be more desirable but is less selective.

Applications

1,1-DCE is mainly used as a comonomer in the polymerization of vinyl chloride, acrylonitrile, and acrylates. It is also used in semiconductor device fabrication for growing high purity silicon dioxide (SiO₂) films.

Polyvinylidene chloride

As with many other alkenes, 1,1-DCE can be polymerised to form polyvinylidene chloride. A very widely used product, cling wrap, or Saran was made from this polymer. During the 1990s research suggested that, in common with many chlorinated carbon compounds, Saran posed a possible danger to health by leaching, especially on exposure to food in microwave ovens. Since 2004, therefore cling wrap's formulation has changed to a form of polyethylene.

1,2-Dichloroethene

1,2-Dichloroethene, commonly called 1,2-dichloroethylene or 1,2-DCE, is an organochloride with the molecular formula C₂H₂Cl₂. It is a highly flammable, colorless liquid with a sharp, harsh odor. It can exist as either of two geometric isomers, cis-1,2-dichloroethene or trans-1,2-dichloroethene, but is often used as a mixture of the two. They have modest solubility in water. These compounds have "scarcely any industrial applications," although they are fundamental given their simple stoichiometries.

Production

cis-DCE is obtainable by the controlled chlorination of acetylene:

Industrially both isomers arise as byproduct of the production of vinyl chloride, which is produced on a vast scale. Unlike vinyl chloride, the 1,2-dichloroethylene isomers do not polymerize.

These compounds are in a variety of applications including electronics cleaning, precision cleaning, and certain metal cleaning applications sold under the trade name VersaTrans.

Safety

These compounds have "moderate oral toxicity to rats."

DCE

DCE may refer to: