1,1-Dichloroethene
Encyclopedia
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.
, 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.
, acrylonitrile
, and acrylate
s. It is also used in semiconductor device fabrication for growing high purity silicon dioxide
(SiO2) films
.
s, 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 polythene.
, including symptoms of sedation, inebriation, convulsions, spasms, and unconsciousness at high concentrations.
Organochloride
An organochloride, organochlorine, chlorocarbon, chlorinated hydrocarbon, or chlorinated solvent is an organic compound containing at least one covalently bonded chlorine atom. Their wide structural variety and divergent chemical properties lead to a broad range of applications...
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-trichloroethane1,1,2-Trichloroethane
1,1,2-Trichloroethane, or 1,1,2-TCA, is an organochloride solvent with the molecular formula C2H3Cl3. It is a colourless, sweet-smelling liquid that does not dissolve in water, but is soluble in most organic solvents...
, a relatively unwanted byproduct in the production of 1,1,1-trichloroethane
1,1,1-Trichloroethane
The organic compound 1,1,1-trichloroethane, also known as methyl chloroform, is a chloroalkane. This colourless, sweet-smelling liquid was once produced industrially in large quantities for use as a solvent...
and 1,2-dichloroethane
1,2-Dichloroethane
The chemical compound 1,2-dichloroethane, commonly known by its old name of ethylene dichloride , is a chlorinated hydrocarbon, mainly used to produce vinyl chloride monomer , the major precursor for PVC production. It is a colourless liquid with a chloroform-like odour...
. The conversion involves a base-catalyzed reaction:
- Cl2CHCH2Cl + NaOH → Cl2C=CH2 + NaCl + H2O
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 chlorideVinyl chloride
Vinyl chloride is the organochloride with the formula H2C:CHCl. It is also called vinyl chloride monomer, VCM or chloroethene. This colorless compound is an important industrial chemical chiefly used to produce the polymer polyvinyl chloride . At ambient pressure and temperature, vinyl chloride...
, acrylonitrile
Acrylonitrile
Acrylonitrile is the chemical compound with the formula C3H3N. This pungent-smelling colorless liquid often appears yellow due to impurities. It is an important monomer for the manufacture of useful plastics. In terms of its molecular structure, it consists of a vinyl group linked to a nitrile...
, and acrylate
Acrylate
The acrylate ion is the ion of acrylic acid.Acrylates are the salts and esters of acrylic acid. They are also known as propenoates ....
s. It is also used in semiconductor device fabrication for growing high purity silicon dioxide
Silicon dioxide
The chemical compound silicon dioxide, also known as silica , is an oxide of silicon with the chemical formula '. It has been known for its hardness since antiquity...
(SiO2) films
Thin film
A thin film is a layer of material ranging from fractions of a nanometer to several micrometers in thickness. Electronic semiconductor devices and optical coatings are the main applications benefiting from thin film construction....
.
Polyvinylidene chloride
As with many other alkeneAlkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...
s, 1,1-DCE can be polymerised to form polyvinylidene chloride
Polyvinylidene chloride
Polyvinylidene chloride is a polymer derived from vinylidene chloride.-History:Ralph Wiley, a Dow Chemical lab worker, accidentally discovered polyvinylidene chloride in 1933. While cleaning laboratory glassware, he came across a vial he could not scrub clean...
. A very widely used product, cling wrap, or Saran
Saran (plastic)
Saran is the trade name for a number of polymers made from vinylidene chloride , along with other monomers. The main advantage of Saran film is its very low permeability to water vapor, flavor and aroma molecules, and oxygen compared with other plastics...
was made from this polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
. 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 polythene.
Safety
The health effects from exposure to 1,1-DCE are primarily on the central nervous systemCentral nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
, including symptoms of sedation, inebriation, convulsions, spasms, and unconsciousness at high concentrations.
External links
- Agency for Toxic Substances and Disease RegistryAgency for Toxic Substances and Disease RegistryThe Agency for Toxic Substances and Disease Registry is a federal public health agency within the United States Department of Health and Human Services. The agency focuses on minimizing human health risks associated with exposure to hazardous substances...
: 1,1-Dichloroethene